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Water, Volume 9, Issue 7 (July 2017)

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Cover Story Constructed wetlands are frequently used for the treatment of agricultural runoff. This research [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial Recent Advances in Soil Moisture Estimation from Remote Sensing
Water 2017, 9(7), 530; doi:10.3390/w9070530
Received: 9 June 2017 / Revised: 5 July 2017 / Accepted: 13 July 2017 / Published: 16 July 2017
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Abstract
Monitoring soil moisture dynamics from local to global scales is essential for a wide range of applications. The field of remote sensing of soil moisture has expanded greatly and the first dedicated soil moisture satellite missions (SMOS, SMAP) were launched, and new missions,
[...] Read more.
Monitoring soil moisture dynamics from local to global scales is essential for a wide range of applications. The field of remote sensing of soil moisture has expanded greatly and the first dedicated soil moisture satellite missions (SMOS, SMAP) were launched, and new missions, such as SENTINEL-1 provide long-term perspectives for land surface monitoring. This special issue aims to summarize the recent advances in soil moisture estimation from remote sensing, including recent advances in retrieval algorithms, validation, and applications of satellite-based soil moisture products. Contributions in this special issue exploit the estimation of soil moisture from both microwave remote sensing data and thermal infrared information. The validation of satellite soil moisture products can be very challenging, due to the different spatial scales of in situ measurements and satellite data. Some papers present validation studies to quantify soil moisture uncertainties. On the other hand, soil moisture downscaling schemes and new methods for soil moisture retrieval from GPS are also addressed by some contributions. Soil moisture data are used in fields like agriculture, hydrology, and climate sciences. Several studies explore the use of soil moisture data for hydrological application such as runoff prediction. Full article
(This article belongs to the Special Issue Remote Sensing of Soil Moisture)

Research

Jump to: Editorial, Review

Open AccessArticle Stability Analysis of Hydrodynamic Pressure Landslides with Different Permeability Coefficients Affected by Reservoir Water Level Fluctuations and Rainstorms
Water 2017, 9(7), 450; doi:10.3390/w9070450
Received: 8 May 2017 / Revised: 14 June 2017 / Accepted: 16 June 2017 / Published: 22 June 2017
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Abstract
It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients
[...] Read more.
It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients are simulated based on saturated-unsaturated seepage theory and finite element analysis. The operating conditions of stability coefficients calculation are reservoir water level variations between 175 m and 145 m, different rates of reservoir water level fluctuations, and a three-day continuous rainstorm. Results show that the stability coefficient of the hydrodynamic pressure landslide decreases with the drawdown of the reservoir water level, and a rapid drawdown rate leads to a small stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. Additionally, the landslide stability coefficient increases as the reservoir water level increases, and a rapid increase in the water level leads to a high stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. The landslide stability coefficient initially decreases and then increases as the reservoir water level declines when the permeability coefficient is greater than 4.64 × 10−5 m/s. Moreover, for structures with the same landslide, the landslide stability coefficient is most sensitive to the change in the rate of reservoir water level drawdown when the permeability coefficient increases from 1.16 × 10−6 m/s to 1.16 × 10−4 m/s. Additionally, the rate of decrease in the stability coefficient increases as the permeability coefficient increases. Finally, the three-day rainstorm leads to a significant reduction in landslide stability, and the rate of decrease in the stability coefficient initially increases and then decreases as the permeability coefficient increases. Full article
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Open AccessArticle Modeling the Fate and Transport of Malathion in the Pagsanjan-Lumban Basin, Philippines
Water 2017, 9(7), 451; doi:10.3390/w9070451
Received: 17 April 2017 / Revised: 15 June 2017 / Accepted: 19 June 2017 / Published: 22 June 2017
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Abstract
Exposure to highly toxic pesticides could potentially cause cancer and disrupt the development of vital systems. Monitoring activities were performed to assess the level of contamination; however, these were costly, laborious, and short-term leading to insufficient monitoring data. However, the performance of the
[...] Read more.
Exposure to highly toxic pesticides could potentially cause cancer and disrupt the development of vital systems. Monitoring activities were performed to assess the level of contamination; however, these were costly, laborious, and short-term leading to insufficient monitoring data. However, the performance of the existing Soil and Water Assessment Tool (SWAT model) can be restricted by its two-phase partitioning approach, which is inadequate when it comes to simulating pesticides with limited dataset. This study developed a modified SWAT pesticide model to address these challenges. The modified model considered the three-phase partitioning model that classifies the pesticide into three forms: dissolved, particle-bound, and dissolved organic carbon (DOC)-associated pesticide. The addition of DOC-associated pesticide particles increases the scope of the pesticide model by also considering the adherence of pesticides to the organic carbon in the soil. The modified SWAT and original SWAT pesticide model was applied to the Pagsanjan-Lumban (PL) basin, a highly agricultural region. Malathion was chosen as the target pesticide since it is commonly used in the basin. The pesticide models simulated the fate and transport of malathion in the PL basin and showed the temporal pattern of selected subbasins. The sensitivity analyses revealed that application efficiency and settling velocity were the most sensitive parameters for the original and modified SWAT model, respectively. Degradation of particulate-phase malathion were also significant to both models. The rate of determination (R2) and Nash-Sutcliffe efficiency (NSE) values showed that the modified model (R2 = 0.52; NSE = 0.36) gave a slightly better performance compared to the original (R2 = 0.39; NSE = 0.18). Results from this study will be able to aid the government and private agriculture sectors to have an in-depth understanding in managing pesticide usage in agricultural watersheds. Full article
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Open AccessArticle Modelling of Ozone Mass-Transfer through Non-Porous Membranes for Water Treatment
Water 2017, 9(7), 452; doi:10.3390/w9070452
Received: 20 May 2017 / Revised: 16 June 2017 / Accepted: 19 June 2017 / Published: 23 June 2017
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Abstract
The mass transfer of ozone and oxygen into water through non-porous membranes was studied using computational fluid dynamics (CFD) modelling and fundamental convection-diffusion theory. Ozone is a gaseous oxidant that is widely applied in drinking water treatment. Membrane contactors are an alternative to
[...] Read more.
The mass transfer of ozone and oxygen into water through non-porous membranes was studied using computational fluid dynamics (CFD) modelling and fundamental convection-diffusion theory. Ozone is a gaseous oxidant that is widely applied in drinking water treatment. Membrane contactors are an alternative to conventional gas dispersion methods for injection of ozone gas mixtures into water. Few studies have explored computational approaches for membrane based ozone transport. In this investigation, quantitative concentration profiles across a single polydimethylsiloxane (PDMS) capillary membrane tube with internal gas flow and external liquid flow were obtained, including single mass transfer resistances and overall mass transfer coefficients for ozone and oxygen for varying membrane lengths, thicknesses, and laminar flow liquid side velocities. Both the influence of diffusivity and solubility of gases in the membrane were considered with the applied model. Previous studies have neglected the solubility of gases in the membranes in their analysis of ozone and oxygen gas fluxes. This work shows that the solubility has a significant impact of the overall mass transfer coefficients, in particular for oxygen. The main resistance for ozone was found in the liquid side, while for oxygen it was in the membrane. Mass transfer correlations based on heat transfer analogies revealed Sherwood (Sh) correlations for ozone and oxygen with good agreement to literature data, indicating that the applied computational model returns sensible results. The outcome of this study provides an initial basis for computational predictions of ozone and oxygen mass transfer for different membrane materials, flow conditions and reactor designs. Full article
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Open AccessArticle Spatio-Temporal Variation and Controlling Factors of Water Quality in Yongding River Replenished by Reclaimed Water in Beijing, North China
Water 2017, 9(7), 453; doi:10.3390/w9070453
Received: 20 March 2017 / Revised: 19 June 2017 / Accepted: 19 June 2017 / Published: 23 June 2017
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Abstract
Reclaimed water is useful for replenishing dried up rivers in North China, although changes in water quality could be an issue. Therefore, it is essential to understand the spatio-temporal variation and the controlling factors of water quality. Samples of Yongding River water were
[...] Read more.
Reclaimed water is useful for replenishing dried up rivers in North China, although changes in water quality could be an issue. Therefore, it is essential to understand the spatio-temporal variation and the controlling factors of water quality. Samples of Yongding River water were collected seasonally, and 24 water quality parameters were analyzed in 2015. All waters were alkaline, and nitrate-nitrogen was the main form of nitrogen, while phosphorus was mostly below detection level. The water quality parameters varied in time and space. Cluster analysis showed a distinct difference between winter and the other seasons and between the natural river section and the section with reclaimed water. Based on the analysis of Gibbs plots, principal component analysis, and ionic relationships, the water chemistry was controlled by dissolution of rocks in natural river section, the quality of replenished water, the effects of dilution, and the reaction of aqueous chemistry in the reclaimed water section. The positive oxidation environment in most of the river water was conducive to the formation of nitrate-nitrogen by nitrification, and not conducive to denitrification. Full article
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Open AccessArticle Treated Greywater Reuse for Hydroponic Lettuce Production in a Green Wall System: Quantitative Health Risk Assessment
Water 2017, 9(7), 454; doi:10.3390/w9070454
Received: 6 May 2017 / Revised: 4 June 2017 / Accepted: 19 June 2017 / Published: 23 June 2017
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Abstract
The scarcity and pollution of freshwater are extremely crucial issues today, and the expansion of water reuse has been considered as an option to reduce its impact. This study aims to assess the efficiency of an integrated greywater treatment system and hydroponic lettuce
[...] Read more.
The scarcity and pollution of freshwater are extremely crucial issues today, and the expansion of water reuse has been considered as an option to reduce its impact. This study aims to assess the efficiency of an integrated greywater treatment system and hydroponic lettuce production as a part of a green wall structure, and to evaluate the health risk associated with the production and consumption of lettuce through a quantitative microbial risk assessment (QMRA) and a chemical health risk assessment. The study was conducted based on the unique configuration of a source separation system; an on-site greywater treatment system; a green wall structure as a polishing step; and hydroponic lettuce production in the green wall structure. The final effluent from the system was used to grow three lettuce varieties by adding urine as a nutrient solution. Both water samples and plant biomass were collected and tested for Escherichia coli (E. coli) and heavy metals contamination. The system has gained a cumulative 5.1 log10 reduction of E. coli in the final effluent and no E. coli found in the plant biomass. The estimated annual infection risk for Cryptosporidium, Campylobacter, and Norovirus was 10−6–10−8, 10−8–10−10, and 10−10–10−11 respectively. These results indicate that the system attained the health-based targets, 10−6 disability adjusted life years (DALYs) per person per year. Similarly, the health risk index (HRI) and targeted hazard quotient (THQ) results did not exceed the permissible level, thus the chemical health risk concern was insignificant. Full article
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Open AccessArticle Combined Impact of Acute Exposure to Ammonia and Temperature Stress on the Freshwater Mussel Unio pictorum
Water 2017, 9(7), 455; doi:10.3390/w9070455
Received: 13 April 2017 / Revised: 8 June 2017 / Accepted: 20 June 2017 / Published: 23 June 2017
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Abstract
Nitrogen compounds, particularly ammonia, and temperature are suspected major stressors for aquatic organisms, but little is known about their impact on globally declining freshwater mussels (Unionoida). In this study, we tested the combined effects of ammonia and temperature stress on painter’s mussel (
[...] Read more.
Nitrogen compounds, particularly ammonia, and temperature are suspected major stressors for aquatic organisms, but little is known about their impact on globally declining freshwater mussels (Unionoida). In this study, we tested the combined effects of ammonia and temperature stress on painter’s mussel (Unio pictorum) survival, filtration behavior, hemocyte abundance, hemocyte mortality and glycogen energy status, at concentrations ranging from 0.3 to 9.0 mg·L1 total ammonia nitrogen (NH4-N) in 96 h acute exposures at two temperatures, 17 °C and 25 °C and a pH of 8.8. The results indicate a low sensitivity of U. pictorum to elevated ammonia concentrations after short-term exposure, although effects on cell morphology were evident and delayed mortality occurred at the highest test concentration. Most pronounced effects were observed for sublethal physiological endpoints due to elevated temperature, but no synergistic effects with ammonia were evident. Temperature increase resulted in significant effects on tissue glycogen, hyalinocyte mortality and clearance rates. Hemocyte mortalities showed a linear dependency on initial mussel activity as measured by their clearance rate. Since the main stressors tested in this study, ammonia and temperature, are predicted to increase in most freshwater ecosystems, their impact on other freshwater mussel species including different life-stages should be comprehensively assessed. Full article
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Open AccessArticle An Investigation into the Effects of Temperature Gradient on the Soil Water–Salt Transfer with Evaporation
Water 2017, 9(7), 456; doi:10.3390/w9070456
Received: 21 April 2017 / Revised: 20 June 2017 / Accepted: 20 June 2017 / Published: 24 June 2017
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Abstract
Temperature gradients exist in the field under brackish water irrigation conditions, especially in northern semi–arid areas of China. Although there are many investigators dedicated to studying the mechanism of brackish water irrigation and the effect of brackish water irrigation on crops, there are
[...] Read more.
Temperature gradients exist in the field under brackish water irrigation conditions, especially in northern semi–arid areas of China. Although there are many investigators dedicated to studying the mechanism of brackish water irrigation and the effect of brackish water irrigation on crops, there are fewer investigations of the effects of temperature gradient on the water–salt transport. Based on the combination of a physical experiment and a mathematical model, this study was conducted to: (a) build a physical model and observe the redistribution of soil water–heat–salt transfer; (b) develop a mathematical model focused on the influence of a temperature gradient on soil water and salt redistribution based on the physical model and validate the proposed model using the measured data; and (c) analyze the effects of the temperature gradient on the soil water–salt transport by comparing the proposed model with the traditional water–salt model in which the effects of temperature gradient on the soil water–salt transfer are neglected. Results show that the soil temperature gradient has a definite influence on the soil water–salt migration. Moreover, the effect of temperature gradient on salt migration was greater than that of water movement. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessArticle Water Temperature Ensemble Forecasts: Implementation Using the CEQUEAU Model on Two Contrasted River Systems
Water 2017, 9(7), 457; doi:10.3390/w9070457
Received: 12 May 2017 / Revised: 16 June 2017 / Accepted: 21 June 2017 / Published: 24 June 2017
Cited by 1 | PDF Full-text (2007 KB) | HTML Full-text | XML Full-text
Abstract
In some hydrological systems, mitigation strategies are applied based on short-range water temperature forecasts to reduce stress caused to aquatic organisms. While various uncertainty sources are known to affect thermal modeling, their impact on water temperature forecasts remain poorly understood. The objective of
[...] Read more.
In some hydrological systems, mitigation strategies are applied based on short-range water temperature forecasts to reduce stress caused to aquatic organisms. While various uncertainty sources are known to affect thermal modeling, their impact on water temperature forecasts remain poorly understood. The objective of this paper is to characterize uncertainty induced to water temperature forecasts by meteorological inputs in two hydrological contexts. Daily ensemble water temperature forecasts were produced using the CEQUEAU model for the Nechako (regulated) and Southwest Miramichi (natural) Rivers for 1–5-day horizons. The results demonstrate that a larger uncertainty is propagated to the thermal forecast in the unregulated river (0.92–3.14 °C) than on the regulated river (0.73–2.29 °C). Better performances were observed on the Nechako with a mean continuous ranked probability score (MCRPS) <0.85 °C for all horizons compared to the Southwest Miramichi (MCRPS ≈ 1 °C). While informing the end-user on future thermal conditions, the ensemble forecasts provide an assessment of the associated uncertainty and offer an additional tool to river managers for decision-making. Full article
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Open AccessArticle Seepage Piping Evolution Characteristics in Bimsoils -An Experimental Study
Water 2017, 9(7), 458; doi:10.3390/w9070458
Received: 11 May 2017 / Revised: 21 June 2017 / Accepted: 22 June 2017 / Published: 24 June 2017
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Abstract
Piping is a kind of seepage failure mode that commonly occurs under the influence of seepage force in soil materials. Many studies have been done to study the characteristics of piping for soil materials, however, the initiation and development mechanism of piping in
[...] Read more.
Piping is a kind of seepage failure mode that commonly occurs under the influence of seepage force in soil materials. Many studies have been done to study the characteristics of piping for soil materials, however, the initiation and development mechanism of piping in bimsoils is poorly understood. In this work, an experimental program was set for investigating the evolution process of piping, in a self-developed servo-controlled flow–erosion–stress coupled testing system. All the studied samples with rock block percentage (RBP) of 30%, 40%, 50%, 60%, and 70%, were produced as a cylindrical shape(50 mm diameter and 100 mm height) by compaction tests with different hammer strike counts to roughly insure the same void ratio. The results show that the amount of rock blocks in bimsoil samples significantly influenced the initiation and development of piping. Furthermore, the stress state has a crucial influence on the critical hydraulic gradient, seepage velocity, permeability, erosion, and migration of soil particles. Moreover, interactions among soil matrix, rock blocks, and rock–soil interfaces control the seepage stability of the bimsoil sample. Full article
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Open AccessArticle An Assessment of Mean Areal Precipitation Methods on Simulated Stream Flow: A SWAT Model Performance Assessment
Water 2017, 9(7), 459; doi:10.3390/w9070459
Received: 2 April 2017 / Revised: 17 June 2017 / Accepted: 21 June 2017 / Published: 24 June 2017
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Abstract
Accurate mean areal precipitation (MAP) estimates are essential input forcings for hydrologic models. However, the selection of the most accurate method to estimate MAP can be daunting because there are numerous methods to choose from (e.g., proximate gauge, direct weighted average, surface-fitting, and
[...] Read more.
Accurate mean areal precipitation (MAP) estimates are essential input forcings for hydrologic models. However, the selection of the most accurate method to estimate MAP can be daunting because there are numerous methods to choose from (e.g., proximate gauge, direct weighted average, surface-fitting, and remotely sensed methods). Multiple methods (n = 19) were used to estimate MAP with precipitation data from 11 distributed monitoring sites, and 4 remotely sensed data sets. Each method was validated against the hydrologic model simulated stream flow using the Soil and Water Assessment Tool (SWAT). SWAT was validated using a split-site method and the observed stream flow data from five nested-scale gauging sites in a mixed-land-use watershed of the central USA. Cross-validation results showed the error associated with surface-fitting and remotely sensed methods ranging from −4.5 to −5.1%, and −9.8 to −14.7%, respectively. Split-site validation results showed the percent bias (PBIAS) values that ranged from −4.5 to −160%. Second order polynomial functions especially overestimated precipitation and subsequent stream flow simulations (PBIAS = −160) in the headwaters. The results indicated that using an inverse-distance weighted, linear polynomial interpolation or multiquadric function method to estimate MAP may improve SWAT model simulations. Collectively, the results highlight the importance of spatially distributed observed hydroclimate data for precipitation and subsequent steam flow estimations. The MAP methods demonstrated in the current work can be used to reduce hydrologic model uncertainty caused by watershed physiographic differences. Full article
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Open AccessArticle A Simple Model of the Variability of Soil Depths
Water 2017, 9(7), 460; doi:10.3390/w9070460
Received: 27 March 2017 / Revised: 13 June 2017 / Accepted: 19 June 2017 / Published: 26 June 2017
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Abstract
Soil depth tends to vary from a few centimeters to several meters, depending on many natural and environmental factors. We hypothesize that the cumulative effect of these factors on soil depth, which is chiefly dependent on the process of biogeochemical weathering, is particularly
[...] Read more.
Soil depth tends to vary from a few centimeters to several meters, depending on many natural and environmental factors. We hypothesize that the cumulative effect of these factors on soil depth, which is chiefly dependent on the process of biogeochemical weathering, is particularly affected by soil porewater (i.e., solute) transport and infiltration from the land surface. Taking into account evidence for a non-Gaussian distribution of rock weathering rates, we propose a simple mathematical model to describe the relationship between soil depth and infiltration flux. The model was tested using several areas in mostly semi-arid climate zones. The application of this model demonstrates the use of fundamental principles of physics to quantify the coupled effects of the five principal soil-forming factors of Dokuchaev. Full article
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Open AccessArticle Snow Precipitation Measured by Gauges: Systematic Error Estimation and Data Series Correction in the Central Italian Alps
Water 2017, 9(7), 461; doi:10.3390/w9070461
Received: 28 December 2016 / Revised: 4 June 2017 / Accepted: 20 June 2017 / Published: 25 June 2017
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Abstract
Precipitation measurements by rain gauges are usually affected by a systematic underestimation, which can be larger in case of snowfall. The wind, disturbing the trajectory of the falling water droplets or snowflakes above the rain gauge, is the major source of error, but
[...] Read more.
Precipitation measurements by rain gauges are usually affected by a systematic underestimation, which can be larger in case of snowfall. The wind, disturbing the trajectory of the falling water droplets or snowflakes above the rain gauge, is the major source of error, but when tipping-bucket recording gauges are used, the induced evaporation due to the heating device must also be taken into account. Manual measurements of fresh snow water equivalent (SWE) were taken in Alpine areas of Valtellina and Vallecamonica, in Northern Italy, and compared with daily precipitation and melted snow measured by manual precipitation gauges and by mechanical and electronic heated tipping-bucket recording gauges without any wind-shield: all of these gauges underestimated the SWE in a range between 15% and 66%. In some experimental monitoring sites, instead, electronic weighing storage gauges with Alter-type wind-shields are coupled with snow pillows data: daily SWE measurements from these instruments are in good agreement. In order to correct the historical data series of precipitation affected by systematic errors in snowfall measurements, a simple ‘at-site’ and instrument-dependent model was first developed that applies a correction factor as a function of daily air temperature, which is an index of the solid/liquid precipitation type. The threshold air temperatures were estimated through a statistical analysis of snow field observations. The correction model applied to daily observations led to 5–37% total annual precipitation increments, growing with altitude (1740 ÷ 2190 m above sea level, a.s.l.) and wind exposure. A second ‘climatological‘ correction model based on daily air temperature and wind speed was proposed, leading to errors only slightly higher than those obtained for the at-site corrections. Full article
(This article belongs to the Special Issue Advances in Hydro-Meteorological Monitoring)
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Open AccessArticle Economic and Energy Criteria for District Meter Areas Design of Water Distribution Networks
Water 2017, 9(7), 463; doi:10.3390/w9070463
Received: 12 May 2017 / Revised: 19 June 2017 / Accepted: 21 June 2017 / Published: 27 June 2017
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Abstract
Water Network Partitioning (WNP) improves water network management, simplifying the computation of water budgets and, consequently, allowing the identification and reduction of water losses. It is achieved by inserting flow meters and gate valves into a network which has been previously clustered into
[...] Read more.
Water Network Partitioning (WNP) improves water network management, simplifying the computation of water budgets and, consequently, allowing the identification and reduction of water losses. It is achieved by inserting flow meters and gate valves into a network which has been previously clustered into subsystems. Generally, the procedures are subdivided into two main steps: the clustering and partitioning phases. At first, network nodes are assigned to each cluster and then the appropriate pipes are selected, in which flow meters or gate valves are to be inserted. In this paper, an improved multilevel-recursive bisection algorithm was used to achieve network clustering. To better allocate the hydraulic devices, the partitioning phase was carried out through the minimization of a novel, multi-objective function, taking simultaneous account of energy and economic aspects. The aim is to define a solution that occupies a minimum possible number of flow meters, simplifying the water budget computation, preserving the hydraulic performances, and minimizing the capital and the operational costs. The procedure was tested on an extensive and real Mexican network, providing different optimal solutions and a smart Decision Support System (DSS) (based on visual diagrams and innovative energy, robustness, and balancing metrics). Full article
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Open AccessArticle Assessing the Effects of Climate Change on Water Quantity and Quality in an Urban Watershed Using a Calibrated Stormwater Model
Water 2017, 9(7), 464; doi:10.3390/w9070464
Received: 19 May 2017 / Revised: 19 June 2017 / Accepted: 21 June 2017 / Published: 27 June 2017
Cited by 1 | PDF Full-text (4920 KB) | HTML Full-text | XML Full-text
Abstract
Assessing climate change (CC) impacts on urban watersheds is difficult due to differences in model spatial and temporal scales, making prediction of hydrologic restoration a challenge. A methodology was developed using an autocalibration tool to calibrate a previously developed Storm Water Management Model
[...] Read more.
Assessing climate change (CC) impacts on urban watersheds is difficult due to differences in model spatial and temporal scales, making prediction of hydrologic restoration a challenge. A methodology was developed using an autocalibration tool to calibrate a previously developed Storm Water Management Model (SWMM) of Difficult Run in Fairfax, Virginia. Calibration was assisted by use of multi-objective optimization. Results showed a good agreement between simulated and observed data. Simulations of CC for the 2041–2068 period were developed using dynamically downscaled North American Regional CC Assessment Program models. Washoff loads were used to simulate water quality, and a method was developed to estimate treatment performed in stormwater control measures (SCMs) to assess water quality impacts from CC. CC simulations indicated that annual runoff volume would increase by 6.5%, while total suspended solids, total nitrogen, and total phosphorus would increase by 7.6%, 7.1%, and 8.1%, respectively. The simulations also indicated that within season variability would increase by a larger percentage. Treatment practices (e.g., bioswale) that were intended to mitigate the negative effects of urban development will need to deal with additional runoff volumes and nutrient loads from CC to achieve the required water quality goals. Full article
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Open AccessArticle Early Warning and Forecasting System of Water Quality Safety for Drinking Water Source Areas in Three Gorges Reservoir Area, China
Water 2017, 9(7), 465; doi:10.3390/w9070465
Received: 7 April 2017 / Revised: 17 June 2017 / Accepted: 22 June 2017 / Published: 28 June 2017
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Abstract
Nowadays, the effects of water pollution accidents on water quality safety and regional residents’ living have attracted worldwide attention. Therefore, the objective of this research is to propose an early warning and forecasting model and develop a visual system of water quality safety
[...] Read more.
Nowadays, the effects of water pollution accidents on water quality safety and regional residents’ living have attracted worldwide attention. Therefore, the objective of this research is to propose an early warning and forecasting model and develop a visual system of water quality safety for drinking water source areas in the Three Gorges Reservoir Area under accident conditions. Based on an Instantaneous Point Source Two-dimensional Water Quality Model and the security requirements of water quality, an early warning and forecasting model was presented, and then the system was advanced by a MATLAB platform. In addition, a hypothetical case was also carried out for the Fenghuangshan drinking water source area. Within 0.040 h to 0.096 h after the accident, the water quality could meet the standard, and the warning level was primary and intermediate, sequentially. From 0.096 h to 11.960 h after the accident, the pollutant concentration exceeded the standard, under which conditions advanced warning started. Then the intermediate and primary warnings restarted in sequence until the pollutant concentration decreased to the background value. Therefore, the proposed model could accurately predict the spatial-temporal change trend of pollutant concentration, and the developed system could efficiently realize early warnings and the forecasting of water quality safety. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Better-Fitted Probability of Hydraulic Conductivity for a Silty Clay Site and Its Effects on Solute Transport
Water 2017, 9(7), 466; doi:10.3390/w9070466
Received: 21 April 2017 / Revised: 10 June 2017 / Accepted: 23 June 2017 / Published: 27 June 2017
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Abstract
The heterogeneous hydraulic conductivity of a subsurface medium is vital to the groundwater flow and solute transport. Probability is efficient for characterizing and quantifying the field characterization of hydraulic conductivity. Compared with sandy mediums, silty clay is paid less attention to due to
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The heterogeneous hydraulic conductivity of a subsurface medium is vital to the groundwater flow and solute transport. Probability is efficient for characterizing and quantifying the field characterization of hydraulic conductivity. Compared with sandy mediums, silty clay is paid less attention to due to its low hydraulic conductivity. For long-term solute transport and seawater intrusion, the low-permeable medium is considered as a remarkably permeable medium. This study reports on a comprehensive investigation on the hydraulic conductivity field of the Ningchegu site, located east of Tianjin City of China. Four layers recognized by 52 boreholes, plain fill, continental silty clay, mud–silt clay and marine silty clay, were deposited from the top to the bottom. The hydraulic conductivities measured via permeameter tests ranged from 2 × 10−6 m/d to 1.6 × 10−1 m/d, which corresponded to the lithology of silty clay. The magnitude and the range of the hydraulic conductivity increased with the depth. Five probability distribution models were tested with the experimental probability, indicating that a Levy stable distribution was more matched than the log-normal, normal, Weibull or gamma distributions. A simple analytical model and a Monte Carlo technique were used to inspect the effect of the silty clay hydraulic conductivity field on the statistical behavior of the solute transport. The Levy stable distribution likely generates higher peak concentrations and lower peak times compared with the widely-used log-normal distribution. This consequently guides us in describing the transport of contaminations in subsurface mediums. Full article
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Open AccessArticle Effects of Water Regime on Spring Wetland Landscape Evolution in Poyang Lake between 2000 and 2010
Water 2017, 9(7), 467; doi:10.3390/w9070467
Received: 25 April 2017 / Revised: 5 June 2017 / Accepted: 19 June 2017 / Published: 27 June 2017
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Abstract
Water regime was one of the most important driving factors in the formation of wetland landscape and the growth and distribution pattern of wetland vegetation. Currently, research on the relationship between wetland landscape and water regime was mostly focused in autumns and winters
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Water regime was one of the most important driving factors in the formation of wetland landscape and the growth and distribution pattern of wetland vegetation. Currently, research on the relationship between wetland landscape and water regime was mostly focused in autumns and winters in Poyang Lake, and lack of research in springs. Based on the nine high-resolution spring remote sensing images during 2000–2010, the classification characteristics of wetland landscape and spatial distribution pattern of vegetation and their succession trends in Poyang Lake were studied through quantitative interpretation technology and multivariate statistical analysis. Combined with water level fluctuations characteristics of the five monitoring hydrological stations (i.e., Hukou, Xingzi, Duzhan, Tangyin and Kangshan) at the Poyang Lake, the inter-annual and intra-annual water level variations of Poyang Lake were analyzed. The study was aimed to investigate the quantitative effects of water regime on the spring wetland landscape and spatial distribution pattern of vegetation and their succession trends in Poyang Lake. The results showed that: (1) the maximum scope of water levels of the five monitoring stations varied from 8.5 m to 13.57 m, and the water level of Poyang lake showed a downward trend, declining at an average rate of 0.16 m per year during 2000–2010; (2) the total area of the 10 types of the landscapes did not change significantly, which was always maintained at about 3026 km 2 and the total area of vegetation coverage showed increasing trend during 2000–2010 in Poyang Lake, with a maximum area in 2008 and a minimum area in 2010; (3) The water level change was consistent with the area of the lake water, and was inconsistent with the areas of the mudflat, vegetation and land-water transition zone. The highest linear fitting degree with water level was the area of the land-water transition zone, followed by the lake water and vegetation. The results were helpful to further explore the eco-hydrology process and its trend at Poyang Lake wetland, a scientific reference for the maintenance of stable ecosystem functions of the seasonal freshwater lake wetland. Full article
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Open AccessArticle Evidence for Submarine Groundwater Discharge into the Black Sea—Investigation of Two Dissimilar Geographical Settings
Water 2017, 9(7), 468; doi:10.3390/w9070468
Received: 5 May 2017 / Revised: 20 June 2017 / Accepted: 22 June 2017 / Published: 27 June 2017
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Abstract
The sustainable management of coastal marine environments requires a comprehensive understanding of the processes related to material transport from land to coastal sea. Besides surface water discharge (e.g., rivers and storm drains), submarine groundwater discharge (SGD) plays a key role since it provides
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The sustainable management of coastal marine environments requires a comprehensive understanding of the processes related to material transport from land to coastal sea. Besides surface water discharge (e.g., rivers and storm drains), submarine groundwater discharge (SGD) plays a key role since it provides a major pathway for solute and particulate transport of contaminants and nutrients, both having considerable potential to cause deterioration of the overall ecological status of coastal environments. The aim of the presented study was the investigation of SGD in two exemplary and dissimilar areas at the Black Sea coast, one in the west (Romania) and one in the east (Georgia). The approach included the assessment of the geological/geographical setting regarding the potential of SGD occurrence, the use of environmental tracer data (222Rn, δ18O, δ2H, salinity), and the evaluation of sea surface temperature patterns near the coastline using satellite data. Besides the individual site specific results, the study revealed that a combined evaluation of tracer data and satellite based information allows SGD localization with satisfying precision. A downscaling approach starting with large scale satellite data is generally recommended, continuing with medium scale tracer patterns and ending with local spot sampling. Full article
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Open AccessArticle ENSO Influence on Rainy Season Precipitation over the Yangtze River Basin
Water 2017, 9(7), 469; doi:10.3390/w9070469
Received: 20 April 2017 / Revised: 11 June 2017 / Accepted: 24 June 2017 / Published: 27 June 2017
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Abstract
The paper explores the impact of El Niño-Southern Oscillation (ENSO) on rainy season precipitation properties over the Yangtze River Basin. The multi-scale moving t-test was used to determine the onset and withdrawal of the rainy season. Results showed the following: (1) Onset
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The paper explores the impact of El Niño-Southern Oscillation (ENSO) on rainy season precipitation properties over the Yangtze River Basin. The multi-scale moving t-test was used to determine the onset and withdrawal of the rainy season. Results showed the following: (1) Onset and withdrawal of the averaged rainy season over the Yangtze River Basin showed a similar distribution and both progressed northwards and westwards. There is a trend for delayed onset of rainy season precipitation over the Yangtze River Basin. A similar trend in the withdrawal of rainy season precipitation was not found. (2) The decaying Central and Eastern Pacific Warming are indicative of wet signals in the Yangtze River Basin, with precipitation anomalies up to 25% above normal. The decaying Eastern Pacific Cooling and developing Eastern Pacific Warming are indicative of dry signals over the Yangtze River Basin, with 5–20% lower than average precipitation (3) ENSO Modoki in the developing phase is more important than the developing ENSO when it comes to present wetter or drier signals. Conversely, the decaying ENSO shows more prominent wet or dry signals than the decaying ENSO Modoki. Full article
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Open AccessArticle Evaluation of Power Ultrasonic Effects on Algae Cells at a Small Pilot Scale
Water 2017, 9(7), 470; doi:10.3390/w9070470
Received: 28 April 2017 / Revised: 6 June 2017 / Accepted: 22 June 2017 / Published: 27 June 2017
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Abstract
It has been recognized for several years that power ultrasound can effectively inactivate algae cells at a laboratory scale. However, although ultrasonic inactivation shows great potential, there are few reports of its use when applied on a large scale. In this study, we
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It has been recognized for several years that power ultrasound can effectively inactivate algae cells at a laboratory scale. However, although ultrasonic inactivation shows great potential, there are few reports of its use when applied on a large scale. In this study, we have investigated the uses of two types of ultrasonic equipment at a small and medium laboratory scale for the control of algae blooms which are commercially available in similar configurations for industrial scale operation. The following equipment was tested using cultured algae suspension: (a) Dual Frequency Reactor (DFR) operating on 1 L in batch mode and 3.5 L in recirculating mode with two resonating plates at different frequencies of 16 and 20 kHz (Advanced Sonic Processing Systems, USA); (b) Sonolator operating in a flow mode treating 5 L using hydrodynamic cavitation (Sonic Corporation, Stanford, CA, USA). The most effective inactivation was obtained using the DFR in batch mode at 60% power setting for 10 min which resulted in a reduction of 60% of the original concentration (measured using optical density OD). In a recirculating loop mode, the treatment of 3.5 L algae suspension with a DFR for 15 min resulted in a reduction of 46% (OD). Ultrasonic treatment of 5 L suspension in a recirculating loop using the Sonolator over 5 h resulted in a reduction of 30% (OD). This study is the first to explore the use of two commercially available ultrasonic systems (DFR and Sonolator) both capable of direct scale-up to industrial levels for the control of algae. It demonstrates that sonication in a recirculating process has the potential to be effective in the treatment of algal cells on a large scale. Full article
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Open AccessArticle Flooding in Delta Areas under Changing Climate: Response of Design Flood Level to Non-Stationarity in Both Inflow Floods and High Tides in South China
Water 2017, 9(7), 471; doi:10.3390/w9070471
Received: 30 March 2017 / Revised: 21 June 2017 / Accepted: 22 June 2017 / Published: 11 July 2017
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Abstract
Climate change has led to non-stationarity in recorded floods all over the world. Although previous studies have widely discussed the design error caused by non-stationarity, most of them explored basins with closed catchment areas. The response of flood level to nonstationary inflow floods
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Climate change has led to non-stationarity in recorded floods all over the world. Although previous studies have widely discussed the design error caused by non-stationarity, most of them explored basins with closed catchment areas. The response of flood level to nonstationary inflow floods and high tidal levels in deltas with a dense river network has hardly been mentioned. Delta areas are extremely vulnerable to floods. To establish reliable standards for flood protection in delta areas, it is crucial to investigate the response of flood level to nonstationary inflow floods and high tidal levels. Pearl River Delta (PRD), the largest delta in South China, was selected as the study area. A theoretical framework was developed to quantify the response of flood level to nonstationary inflow floods and the tidal level. When the non-stationarity was ignored, error up to 18% was found in 100-year design inflow floods and up to 14% in 100-year design tidal level. Meanwhile, flood level in areas that were ≤22 km away from the outlets mainly responded to the nonstationary tidal level, and that ≥45 km to the nonstationary inflow floods. This study will support research on the non-stationarity of floods in delta areas. Full article
(This article belongs to the Special Issue Hillslope and Watershed Hydrology)
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Open AccessArticle Performance of an Agricultural Wetland-Reservoir-Irrigation Management System
Water 2017, 9(7), 472; doi:10.3390/w9070472
Received: 30 April 2017 / Revised: 14 June 2017 / Accepted: 18 June 2017 / Published: 28 June 2017
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Abstract
Constructed wetlands (CW) have gained recognition as a management option for the treatment of various agricultural wastewaters. This study involved the design, construction, and initial evaluation of a wetland-reservoir-irrigation (WRI) system. The system was established in Truro, Nova Scotia, Canada, with the goal
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Constructed wetlands (CW) have gained recognition as a management option for the treatment of various agricultural wastewaters. This study involved the design, construction, and initial evaluation of a wetland-reservoir-irrigation (WRI) system. The system was established in Truro, Nova Scotia, Canada, with the goal to capture, treat, and re-use agricultural sub-surface drainage water. It consisted of a 1.8-ha area of a cropped field that was systematically tile drained. Drainage water was directed through a 2-cell CW and then into a reservoir-irrigation pond. Flow rate hydraulics, residence time distributions, and treatment efficiencies for nitrate-nitrogen (NO3-N) and Escherichia coli (E. coli) were monitored for 14 months. Mass reductions of NO3-N and E. coli from the CW were 67.6% and 63.3%, respectively. However, average E. coli concentrations increased to 178 CFU 100 mL−1 in the reservoir during the warm season. It may therefore be best to use reservoir water for irrigation of crops that are not consumed raw. To aid in the future design of similar systems, mean first-order rate constants (ks) for NO3-N and E. coli were calculated to be 8.0 and 6.4 m y−1, respectively. The volume of water collected in the reservoir exceeded typical irrigation requirements of the drained land and could therefore provide irrigation to additional land beyond the drainage area. Full article
(This article belongs to the Special Issue Treatment Wetlands for Nutrient Removal)
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Open AccessArticle Water Molecules in a Carbon Nanotube under an Applied Electric Field at Various Temperatures and Pressures
Water 2017, 9(7), 473; doi:10.3390/w9070473
Received: 28 February 2017 / Revised: 9 June 2017 / Accepted: 23 June 2017 / Published: 28 June 2017
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Abstract
Water confined in carbon nanotubes (CNTs) under the influence of an electric field exhibits behavior different to that of bulk water. Such behavior is fascinating from a nanoscience point of view and has potential application in nanotechnology. Using molecular dynamics simulations, we investigate
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Water confined in carbon nanotubes (CNTs) under the influence of an electric field exhibits behavior different to that of bulk water. Such behavior is fascinating from a nanoscience point of view and has potential application in nanotechnology. Using molecular dynamics simulations, we investigate the structure of water molecules in an ( 8 , 8 ) CNT, under an electric field at various temperatures and pressures. In the absence of an electric field, water in the CNT has an ordered (solid-like) structure at temperatures of 200 K and 250 K. The solid-like structure of water at these low temperatures exhibits ferroelectric properties. At 300 K, the structure of water is solid-like or disordered (liquid-like), i.e., an unstable structure. This indicates that a melting point occurs at around these conditions. Increasing the pressure to 10 MPa does not change the structure at 300 K. At 350 K, water is completely melted and has only a disordered structure. Under an applied electric field of 1 V/nm, water forms a solid-like structure at all simulation temperatures up to 350 K. This suggests that the electric field induces a phase transition from liquid to ice-nanotube, at temperatures as high as 350 K. The structure of the ice-nanotube under an applied electric field differs from that formed in the absence of an electric field at low temperature. The electrostatic interaction within the ice-nanotube under an electric field is stronger than that in the absence of an electric field. Full article
(This article belongs to the Special Issue Electrohydrodynamic Liquid Bridges and Electrified Water)
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Open AccessArticle Dependence of Sediment Suspension Viscosity on Solid Concentration: A Simple General Equation
Water 2017, 9(7), 474; doi:10.3390/w9070474
Received: 27 May 2017 / Revised: 24 June 2017 / Accepted: 26 June 2017 / Published: 28 June 2017
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Abstract
In this study, a simple and new parametric equation is proposed that describes the relative viscosity of a suspension as a function of suspended solid concentration, covering a range from very dilute to highly concentrated states, based on Costa (2005). The proposed viscosity
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In this study, a simple and new parametric equation is proposed that describes the relative viscosity of a suspension as a function of suspended solid concentration, covering a range from very dilute to highly concentrated states, based on Costa (2005). The proposed viscosity law depends mainly on the solid volumetric concentration and maximum packing fraction at which a regime transition occurs. Furthermore, the viscosity of dilute as well as a highly-concentrated kaolinite suspension (in excess of 40% and lower than 50%) was measured in a coaxial cylinder rheometer. The proposed formula shows a capability of fitting the measured bulk viscosity into the hyper-concentrated regime in the experiment. Finally, the proposed equation could also be found to show a good fitting relationship with published experimental results on partially crystallised Li2Si2O5 melt and partially melted granite with solid contents from 75% to 95%. Full article
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Open AccessArticle Runoff Responses to Climate and Land Use/Cover Changes under Future Scenarios
Water 2017, 9(7), 475; doi:10.3390/w9070475
Received: 5 April 2017 / Revised: 24 June 2017 / Accepted: 26 June 2017 / Published: 29 June 2017
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Abstract
Climate and land use/cover (LUC) are the two most significant factors that directly affect the runoff process. However, most research on runoff response has focused mainly on projected climate variation, while future LUC variability has been neglected. Therefore, the objective of this study
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Climate and land use/cover (LUC) are the two most significant factors that directly affect the runoff process. However, most research on runoff response has focused mainly on projected climate variation, while future LUC variability has been neglected. Therefore, the objective of this study is to examine the impacts of projected climate and LUC changes on runoff. Future climate scenarios are projected using the Quantile Mapping (QM) method, and future LUC scenarios are predicted with the Cellular Automaton-Markov (CA-Markov) model. Three different scenarios are simulated and compared to evaluate their impacts: Scenario 1 (LUC of 2010 and climate during the 2011–2050 period, abbreviated S1), Scenario 2 (LUC of 2010, 2020, 2030, 2040 and 2050 and climate of the historical wet year, normal year and dry year, abbreviated S2) and Scenario 3 (LUC of 2010, 2020, 2030, 2040 and 2050 and corresponding climate projections of 2011–2020, 2021–2030, 2031–2040 and 2041–2050 period, abbreviated S3). These three scenarios are then input into the Soil and Water Assessment Tool (SWAT) model to assess runoff responses. Beijiang River Basin, located in southern China, is used in this case study. The results obtained from S1, S2 and S3 show that runoff change in this basin is mainly caused by climate change; warmer temperatures and greater precipitation increase runoff. LUC change has little influence on runoff at the whole-basin scale, but changes in runoff components are more notable in the urban area than in the natural region at the sub-watershed level. The impact of LUC change in urbanized region on runoff components differ obviously among the wet, normal and dry years, and surface runoff and groundwater are found to be more sensitive to urbanization. Runoff depth is predicted to increase in this basin under the impacts of both climate and LUC changes in the future. Climate change brings greater increase in water yield and surface runoff, whereas LUC change leads to changes in allocation between surface runoff and groundwater in the urban region. Full article
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Open AccessArticle Effects of N/S Molar Ratio on Product Formation in Psychrophilic Autotrophic Biological Removal of Sulfide
Water 2017, 9(7), 476; doi:10.3390/w9070476
Received: 13 March 2017 / Revised: 20 June 2017 / Accepted: 27 June 2017 / Published: 29 June 2017
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Abstract
The excessive H2S presence in water and wastewater can lead to corrosion, toxicity, and biological processes inhibition—i.e., anaerobic digestion. Production of H2S can occur in psychrophilic conditions. Biological removal of HS by addition of NO3 as
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The excessive H2S presence in water and wastewater can lead to corrosion, toxicity, and biological processes inhibition—i.e., anaerobic digestion. Production of H2S can occur in psychrophilic conditions. Biological removal of HS by addition of NO3 as an electron acceptor under psychrophilic (10 °C) conditions in a continuous flow experiment is evaluated here. Four different N/S molar ratios—0.35, 0.40, 0.60, and 1.30—were tested in an expanded granular sludge bed (EGSB) reactor. Samples were analyzed daily by ion chromatography. Efficient psychrophilic HS removal with sulfur products oxidation control by NO3 supply is documented. The highest HS removal was obtained at N/S = 0.35 and 1.30 (89.1 ± 2.2 and 89.6 ± 2.9%). Removal of HS was less at mid-N/S with the lowest value (76.9 ± 2.6%) at N/S = 0.60. NO3 removal remained high for all N/S ratios. N/S molar ratio influenced the sulfur products distribution with less S0 and increase in SO42− effluent concentration with increasing N/S ratio. Oxidation of HS and accumulated S0 occurred simultaneously at N/S ratios >0.35. The observations are explained by culture flexibility in utilizing available resources for energy gain. Full article
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Open AccessFeature PaperArticle Effects of the Food-to-Microorganism (F/M) Ratio on N2O Emissions in Aerobic Granular Sludge Sequencing Batch Airlift Reactors
Water 2017, 9(7), 477; doi:10.3390/w9070477
Received: 30 April 2017 / Revised: 11 June 2017 / Accepted: 22 June 2017 / Published: 29 June 2017
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Abstract
The present study investigated the effect of the food-to-microorganism (F/M) ratio on nitrous oxide (N2O) emissions in aerobic granular sludge sequencing batch airlift reactors. Three identical sequencing batch airlift reactors were fed with sodium acetate-based wastewater at different chemical oxygen demand
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The present study investigated the effect of the food-to-microorganism (F/M) ratio on nitrous oxide (N2O) emissions in aerobic granular sludge sequencing batch airlift reactors. Three identical sequencing batch airlift reactors were fed with sodium acetate-based wastewater at different chemical oxygen demand (COD) concentrations, resulting in F/M ratios from 0.2 to 0.67 g COD/g SS. The results indicated that N2O emissions increased with an increase of the F/M ratio. N2O emissions at the high F/M ratio of 0.67 g COD/g SS were the highest (4.4 ± 0.94 mg/d). The main source of the high N2O emissions at the F/M ratio of 0.67 g COD/g SS was nitrifier denitrification, rather than heterotrophic denitrification, confirmed by the qPCR (quantitative real-time PCR) results. The heterotrophic denitrification was destroyed by the DO (dissolved oxygen) diffusing into the sludge particles with porous structures. This study offers theoretical support to study the N2O emissions in aerobic granular sludge, and can provide guidance for conducting risk assessment and enhancing our ability to predict N2O production in aerobic granular sludge at different F/M ratios. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Pixel-Level Spatiotemporal Analyses of Vegetation Fractional Coverage Variation and Its Influential Factors in a Desert Steppe: A Case Study in Inner Mongolia, China
Water 2017, 9(7), 478; doi:10.3390/w9070478
Received: 23 April 2017 / Revised: 23 June 2017 / Accepted: 27 June 2017 / Published: 29 June 2017
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Abstract
Determining vegetation variation and its influential factors in a desert steppe under the impacts of climate change and human activities is crucial and meaningful for improving the understanding of desertification and taking targeted measures in ecological restoration. As compared to a large spatial
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Determining vegetation variation and its influential factors in a desert steppe under the impacts of climate change and human activities is crucial and meaningful for improving the understanding of desertification and taking targeted measures in ecological restoration. As compared to a large spatial scale such as a region or a whole catchment, which are more common in published studies, a micro perspective at the pixel level is provided in this study to investigate the vegetation fractional coverage dynamics and build the correlations between vegetation fractional coverage and its multiple influential factors, including precipitation, temperature, soil water, groundwater and human activities in a desert steppe region in the Inner Mongolia Autonomous Region, China. The average vegetation fractional coverage in August for the years 2000–2011 is 0.38 in the study area. The interaction of rain (R = 0.80) and heat (R = −0.76) significantly determines the growth and distribution of the vegetation in the study area. Besides, the effects of some other factors on vegetation fractional coverage should not be neglected, including groundwater (R = 0.04), available water content of soil (R = 0.23) and livestock density (R = 0.28). From the perspective of centre dynamics for the years 2000–2011, the annual precipitation centre has better synchronism with the vegetation centre, while the movement of the temperature centre is more stable. Full article
(This article belongs to the Special Issue Water-Soil-Vegetation Dynamic Interactions in Changing Climate)
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Open AccessArticle Fate of Trace Organic Compounds in Granular Activated Carbon (GAC) Adsorbers for Drinking Water Treatment
Water 2017, 9(7), 479; doi:10.3390/w9070479
Received: 30 April 2017 / Revised: 23 June 2017 / Accepted: 26 June 2017 / Published: 30 June 2017
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Abstract
Granular activated carbon (GAC) adsorbers for drinking water treatment were operated for approx. 14 months and the breakthrough of dissolved organic carbon (DOC) and trace organic chemicals (TOrCs) was monitored. Effluent concentration profiles of gabapentin and valsartan acid increase already at throughputs of
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Granular activated carbon (GAC) adsorbers for drinking water treatment were operated for approx. 14 months and the breakthrough of dissolved organic carbon (DOC) and trace organic chemicals (TOrCs) was monitored. Effluent concentration profiles of gabapentin and valsartan acid increase already at throughputs of <10,000 BV. The corresponding breakthrough curves flatten out without reaching the influent concentration level. This strongly indicates biological degradation of these substances in the GAC adsorbers under aerobic conditions, contributing to a more efficient use of GAC. The observed biodegradation in pilot GAC adsorbers also confirms recent reports of biodegradation of gabapentin and valsartan acid during managed aquifer recharge. Oxypurinol is comparatively well adsorbed and no breakthrough was observed during the experimental period. Adsorption capacity and breakthrough characteristics of oxypurinol appear very similar to carbamazepine. Breakthrough of GAC adsorbers operated with drinking water was compared to those of groundwater-fed adsorbers. The results show, that it is generally advisable to use previously aerated influents for GAC fixed-bed adsorbers because this can substantially improve biological removal of otherwise poorly adsorbable compounds and ensure full GAC accessibility for adsorbates by avoiding the undesirable formation of inorganic precipitates on adsorption sites. Full article
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Open AccessArticle Impact of Geophysical and Datum Corrections on Absolute Sea-Level Trends from Tide Gauges around Taiwan, 1993–2015
Water 2017, 9(7), 480; doi:10.3390/w9070480
Received: 30 April 2017 / Revised: 14 June 2017 / Accepted: 28 June 2017 / Published: 1 July 2017
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Abstract
The Taiwanese government has established a complete tide gauge network along the coastline for accurate sea-level monitoring. In this study, we analyze several factors impacting the determination of absolute or geocentric sea-level trends—including ocean tides, inverted barometer effect, datum shift, and vertical land
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The Taiwanese government has established a complete tide gauge network along the coastline for accurate sea-level monitoring. In this study, we analyze several factors impacting the determination of absolute or geocentric sea-level trends—including ocean tides, inverted barometer effect, datum shift, and vertical land motion—using tide gauge records near Taiwan, from 1993–2015. The results show that datum shifts and vertical land motion have a significant impact on sea-level trends with a respective average contribution of 7.3 and 8.0 mm/yr, whereas ocean tides and inverted barometer effects have a relatively minor impact, representing 9% and 14% of the observed trend, respectively. These results indicate that datum shifts and vertical land motion effects have to be removed in the tide gauge records for accurate sea-level estimates. Meanwhile, the estimated land motions show that the southwestern plain has larger subsidence rates, for example, the Boziliao, Dongshi, and Wengang tide gauge stations exhibit a rate of 24–31 mm/yr as a result of groundwater pumping. We find that the absolute sea-level trends around Taiwan derived from tide gauges or satellite altimetry agree well with each other, and are estimated to be 2.2 mm/yr for 1993–2015, which is significantly slower than the global average sea-level rise trend of 3.2 mm/yr from satellite altimeters. Finally, a recent hiatus in sea-level rise in this region exhibits good agreement with the interannual and decadal variabilities associated with the El Niño-Southern Oscillation and Pacific Decadal Oscillation. Full article
(This article belongs to the Special Issue Sea Level Changes)
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Open AccessArticle Evaluating Annual Maximum and Partial Duration Series for Estimating Frequency of Small Magnitude Floods
Water 2017, 9(7), 481; doi:10.3390/w9070481
Received: 1 May 2017 / Revised: 22 June 2017 / Accepted: 24 June 2017 / Published: 30 June 2017
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Abstract
Understanding the nature of frequent floods is important for characterising channel morphology, riparian and aquatic habitat, and informing river restoration efforts. This paper presents results from an analysis on frequency estimates of low magnitude floods using the annual maximum and partial series data
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Understanding the nature of frequent floods is important for characterising channel morphology, riparian and aquatic habitat, and informing river restoration efforts. This paper presents results from an analysis on frequency estimates of low magnitude floods using the annual maximum and partial series data compared to actual flood series. Five frequency distribution models were fitted to data from 24 gauging stations in the Great Barrier Reef (GBR) lagoon catchments in north-eastern Australia. Based on the goodness of fit test, Generalised Extreme Value, Generalised Pareto and Log Pearson Type 3 models were used to estimate flood frequencies across the study region. Results suggest frequency estimates based on a partial series are better, compared to an annual series, for small to medium floods, while both methods produce similar results for large floods. Although both methods converge at a higher recurrence interval, the convergence recurrence interval varies between catchments. Results also suggest frequency estimates vary slightly between two or more partial series, depending on flood threshold, and the differences are large for the catchments that experience less frequent floods. While a partial series produces better frequency estimates, it can underestimate or overestimate the frequency if the flood threshold differs largely compared to bankfull discharge. These results have significant implications in calculating the dependency of floodplain ecosystems on the frequency of flooding and their subsequent management. Full article
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Open AccessArticle Kinetic Modelling of the Removal of Multiple Heavy Metallic Ions from Mine Waste by Natural Zeolite Sorption
Water 2017, 9(7), 482; doi:10.3390/w9070482
Received: 17 May 2017 / Revised: 21 June 2017 / Accepted: 27 June 2017 / Published: 1 July 2017
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Abstract
This study investigates the sorption of heavy metallic ions (HMIs), specifically lead (Pb2+), copper (Cu2+), iron (Fe3+), nickel (Ni2+) and zinc (Zn2+), by natural zeolite (clinoptilolite). These HMIs are combined in single-, dual-,
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This study investigates the sorption of heavy metallic ions (HMIs), specifically lead (Pb2+), copper (Cu2+), iron (Fe3+), nickel (Ni2+) and zinc (Zn2+), by natural zeolite (clinoptilolite). These HMIs are combined in single-, dual-, triple-, and multi-component systems. The batch mode experiments consist of a total initial concentration of 10 meq/L normality for all systems, acidified to a pH of 2 by concentrated nitric (HNO3) acid. A zeolite dosage of 4 g per 100 mL of synthetic nitrate salt aqueous solution is applied, for a contact period of 5 to 180 min. Existing kinetic models on HMIs sorption are limited for multi-component system combinations. Therefore, this study conducts kinetic analysis by both reaction and diffusion models, to quantify the sorption process. The study concludes that the process correlates best with the pseudo-second-order (PSO) kinetic model. In the multi-component system combining all five HMIs, the initial sorption rate and theoretical equilibrium capacity are determined as 0.0033 meq/g·min and 0.1159 meq/g, respectively. This provides significant insight into the mechanisms associated with the sorption process, as well as contributing to the assessment of natural zeolite as a sorbent material in its application in industrial wastewater treatment. Full article
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Open AccessArticle Analyzing the Effect of Ocean Internal Variability on Depth-Integrated Steric Sea-Level Rise Trends Using a Low-Resolution CESM Ensemble
Water 2017, 9(7), 483; doi:10.3390/w9070483
Received: 14 March 2017 / Revised: 8 May 2017 / Accepted: 27 June 2017 / Published: 1 July 2017
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Abstract
Ocean heat uptake is a key indicator of climate change, in part because it contributes to sea-level rise. Quantifying the uncertainties surrounding ocean heat uptake and sea-level rise are important in assessing climate-related risks. Here, comprehensive global climate model ensembles are used to
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Ocean heat uptake is a key indicator of climate change, in part because it contributes to sea-level rise. Quantifying the uncertainties surrounding ocean heat uptake and sea-level rise are important in assessing climate-related risks. Here, comprehensive global climate model ensembles are used to evaluate uncertainties surrounding decadal trends in depth-integrated global steric sea-level rise due to thermal expansion of the ocean. Results are presented against observational estimates, which are used as a guide to the state of recent literature. The first ensemble uses the Community Earth System Model (CESM), which samples the effects of internal variability within the coupled Earth system including contributions from the sub-surface ocean. We compare and contrast these results with an ensemble based on the Coupled Model Intercomparison Project Phase 5 (CMIP5), which samples the combined effects of structural model differences and internal variability. The effects of both internal variability and structural model differences contribute substantially to uncertainties in modeled steric sea-level trends for recent decades, and the magnitude of these effects varies with depth. The 95% range in total sea-level rise trends across the CESM ensemble is 0.151 mm·year−1 for 1957–2013, while this range is 0.895 mm·year−1 for CMIP5. These ranges increase during the more recent decade of 2005–2015 to 0.509 mm·year−1 and 1.096 mm·year−1 for CESM and CMIP5, respectively. The uncertainties are amplified for regional assessments, highlighting the importance of both internal variability and structural model differences when considering uncertainties surrounding modeled sea-level trends. Results can potentially provide useful constraints on estimations of global and regional sea-level variability, in particular for areas with few observations such as the deep ocean and Southern Hemisphere. Full article
(This article belongs to the Special Issue Sea Level Changes)
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Open AccessArticle Halosteric Sea Level Changes during the Argo Era
Water 2017, 9(7), 484; doi:10.3390/w9070484
Received: 29 April 2017 / Revised: 21 June 2017 / Accepted: 28 June 2017 / Published: 1 July 2017
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Abstract
In addition to the sea level (SL) change, or anomaly (SLA), due to ocean thermal expansion, total steric SLA (SSLA, all change to the existing volume of ocean water) is also affected by ocean salinity variation. Less attention, however, has been paid to
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In addition to the sea level (SL) change, or anomaly (SLA), due to ocean thermal expansion, total steric SLA (SSLA, all change to the existing volume of ocean water) is also affected by ocean salinity variation. Less attention, however, has been paid to this halosteric effect, due to the global dominance of thermosteric SLA (TSLA) and the scarcity of salinity measurements. Here, we analyze halosteric SLA (HSLA) since 2005, when Argo data reached near-global ocean coverage, based on several observational products. We find that, on global average, the halosteric component contributes negatively by ~5.8% to SSLA during the 2005–2015 period, and reveals a modest correlation (~0.38) with ENSO on the inter-annual scale. Vertically, the global ocean was saltier in the upper 200-m and fresher within 200 to 600-m since 2005, while the change below 600-m was not significantly different from zero. The upper 200-m changes dominate the HSLA, suggesting the importance of surface fresh water flux forcing; meanwhile, the ocean dynamic might also play a role. The inconsistent pattern of salinity trend between upper 200-m and 200 to 600-m implies the importance of ocean dynamics. Our analysis suggests that local salinity changes cannot be neglected, and can even play a more important role in SSLA than the thermosteric component in some regions, such as the Tropical/North Pacific Ocean, the Southern Ocean, and the North Atlantic Ocean. This study highlights the need to better reconstruct historical salinity datasets, to better monitor the past SSLA changes. Also, it is important to understand the mechanisms (ocean dynamics vs. surface flux) related to regional ocean salinity changes. Full article
(This article belongs to the Special Issue Sea Level Changes)
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Open AccessArticle Transport of Conservative and “Smart” Tracers in a First-Order Creek: Role of Transient Storage Type
Water 2017, 9(7), 485; doi:10.3390/w9070485
Received: 29 April 2017 / Revised: 26 June 2017 / Accepted: 28 June 2017 / Published: 2 July 2017
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Abstract
Using “smart” tracers such as Resazurin (Raz) allows assessment of sediment-water interactions and associated biological activity in streams. We compared two approaches to simulate the effects of transient storage (TS) on the transport of conservative and reactive tracers. The first approach considered TS
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Using “smart” tracers such as Resazurin (Raz) allows assessment of sediment-water interactions and associated biological activity in streams. We compared two approaches to simulate the effects of transient storage (TS) on the transport of conservative and reactive tracers. The first approach considered TS as composed of metabolically active and metabolically inactive compartments, while the second model approach accounted for the surface transient storage (STS) and hyporheic transient storage (HTS). Experimental data were collected at a perennial first-order creek in Maryland, MD, USA, by injecting the conservative tracer bromide (Br) and the reactive (Raz) tracer and sampling water at two weir stations. The STS–HTS approach led to a more accurate simulation of Br transport and tails of the Raz and its product Rezorufin (Rru) breakthrough curves. Sediments support large microbial communities, and the STS–HTS model in creeks provides additional parameters to characterize the habitats of microbial water-quality indicator organisms. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle Changes in Reference Evapotranspiration and Its Contributing Factors in Jiangsu, a Major Economic and Agricultural Province of Eastern China
Water 2017, 9(7), 486; doi:10.3390/w9070486
Received: 10 April 2017 / Revised: 14 June 2017 / Accepted: 30 June 2017 / Published: 2 July 2017
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Abstract
Reference evapotranspiration (ETref) is a key parameter of hydro-meteorological studies as well as water resource planning. In this study, we adopted the Penman–Monteith FAO 56 model to estimate ETref and through the differential equation and detrending method to determine
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Reference evapotranspiration (ETref) is a key parameter of hydro-meteorological studies as well as water resource planning. In this study, we adopted the Penman–Monteith FAO 56 model to estimate ETref and through the differential equation and detrending method to determine sensitivities and the contributions of four meteorological parameters to ETref based on daily weather data from 60 stations of Jiangsu province during 1961–2015. Results reveal that ETref and its trends in the three sub-regions of the Jiangsu province had a significant spatial heterogeneity. A significant decreasing tendency of ETref (p < 0.001) was observed in the Huaibei region, while a slightly increasing tendency was identified in the Jianghuai and Sunan regions. These changes of ETref were caused by a significant increasing trend in air temperature (TA) and significant decreasing trends in wind speed (WS), sunshine duration (SD) as well as a non-significant change trend in actual vapor pressure (VP). However, the VP was the meteorological parameter to which ETref was most sensitive, whereas ETref was more sensitive to TA and SD in the summer but less so in the winter; the least sensitive factor, WS, had the opposite trend. Across the whole region, WS contributed most to ETref, followed by SD, while the positive contribution of TA to ETref could not offset the negative contributions of WS and SD. Although the effect of VP on changes in ETref is small, it could not be ignored, especially in the winter. The reverse relationship between increasing TA and decreasing ETref, namely the “evaporation paradox,” occurred in Jiangsu province. Thus, the outcomes of this study will contribute to thorough insight into the response to changes in ETref to the provincial water planning and management in eastern China. Full article
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Open AccessArticle Using Chemically Enhanced Primary Treatment (CEPT) as a Pretreatment Option for Anaerobic Digestate from Cattle Manure Digestion System
Water 2017, 9(7), 487; doi:10.3390/w9070487
Received: 28 May 2017 / Revised: 27 June 2017 / Accepted: 28 June 2017 / Published: 3 July 2017
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Abstract
Anaerobic digestate from cattle manure fermentation may pose a threat to the environment. How to stabilize the digestate’s characteristics so that they do not disturb the bio-system is a critical issue for digestate management. Chemically enhanced primary treatment (CEPT) was investigated as a
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Anaerobic digestate from cattle manure fermentation may pose a threat to the environment. How to stabilize the digestate’s characteristics so that they do not disturb the bio-system is a critical issue for digestate management. Chemically enhanced primary treatment (CEPT) was investigated as a pretreatment option for digestate treatment. The performance of CEPT for digestate management was carried out under rapid mixing (200 r/min) and slow stirring (40 r/min), respectively. The optimal dosage of ferric chloride (FeCl3) was 40 mg/L. The combination of FeCl3 and anionic polyacrylamide (APAM) had no obvious influence on TP removal, while COD removal efficiency was improved by 15.4%. The digestate pH and temperature remained stable for CEPT application and required no adjustment. The results indicate that CEPT was effective and feasible in enhancing the removal of COD and TP for digestate pretreatment by using FeCl3 and APAM. Full article
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Open AccessArticle Optimal Use of Agricultural Water and Land Resources through Reconfiguring Crop Planting Structure under Socioeconomic and Ecological Objectives
Water 2017, 9(7), 488; doi:10.3390/w9070488
Received: 5 May 2017 / Revised: 28 June 2017 / Accepted: 29 June 2017 / Published: 4 July 2017
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Abstract
Many economic, social and ecological problems can be attributed to the scarcity and mismanagement of water and land resources. In this study, a multi-objective fuzzy–robust programming (MOFRP) method was developed for supporting the optimal use of land and water resources in agriculture. MOFRP
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Many economic, social and ecological problems can be attributed to the scarcity and mismanagement of water and land resources. In this study, a multi-objective fuzzy–robust programming (MOFRP) method was developed for supporting the optimal use of land and water resources in agriculture. MOFRP improved existing methods through taking ecological services of crop cultivation into account. It was also capable of reflecting fuzziness in preferences, priorities and parameters that were largely neglected in previous agricultural decision making. This method was applied to address a case in arid northwestern China. Optimal plans of crop cultivation reconfiguration were generated for sustaining local development under economic, ecological and social objectives as well as physical restraints in water and land resources. Compared to the status quo, the optimized plan would increase economic and ecological benefits by 12.2% and 18.8%, respectively. The efficiency of irrigation water could also be enhanced with the economic and ecological benefits per unit water being raised and the water consumption per unit land being reduced. The comparisons of the MOFRP model to four alternatives validated that it was capable of achieving satisfactory benefits and reducing system-violation risks without neglecting valuable uncertain information and ecological services of crops. The proposed method was also applicable to other multi-objective management problems under uncertainty without loss of generality. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Variability of Spatially Grid-Distributed Precipitation over the Huaihe River Basin in China
Water 2017, 9(7), 489; doi:10.3390/w9070489
Received: 8 March 2017 / Revised: 23 May 2017 / Accepted: 22 June 2017 / Published: 5 July 2017
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Abstract
This study investigates spatial characteristics of annual and decadal precipitation in the Huaihe River basin. Daily precipitation data, obtained from meteorological gauges, are analyzed for a 51-year period, from 1961 to 2011. Precipitation is analyzed in grids (5 km2) with respect
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This study investigates spatial characteristics of annual and decadal precipitation in the Huaihe River basin. Daily precipitation data, obtained from meteorological gauges, are analyzed for a 51-year period, from 1961 to 2011. Precipitation is analyzed in grids (5 km2) with respect to temporal variability. The spatial distribution and intensity of annual rainfall (mm/10 year), determined by the linear regression method, reveals a slight increase of 3 mm/10 year over the basin. However, the trend did not present a significant change at 95% significance level in the most of basin. Precipitation is mostly increasing for each ten-year periods during the total 51 years. The annual precipitation randomicity was calculated from the non-uniform coefficient Cv (coefficient of variation) test and showed a significant non-uniform spatial distribution, indicating that randomicity of annual rainfall was the moderate variability. The Pettitt test determined that the abrupt change points occurred mainly in 1965, 1975 and 2002. Wavelet analysis showed that cyclic variations appeared almost every 5 to 10 years, accounting for 36% of the basin area. Meanwhile, these cycles tended to be delimited by the abrupt change points. This study aims to provide insights for water resources management, mitigation of climate change effects and water supply in the Huaihe River basin and surrounding watersheds. Full article
(This article belongs to the Special Issue Hillslope and Watershed Hydrology)
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Open AccessArticle Agricultural Water Productivity Oriented Water Resources Allocation Based on the Coordination of Multiple Factors
Water 2017, 9(7), 490; doi:10.3390/w9070490
Received: 28 March 2017 / Revised: 12 June 2017 / Accepted: 20 June 2017 / Published: 5 July 2017
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Abstract
Agricultural water productivity (AWP), which is associated with multiple factors, is an important index for measuring the effectiveness of agricultural water management. The purpose of this study is to promote AWP through optimally allocating limited agricultural water resources with the coordination of related
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Agricultural water productivity (AWP), which is associated with multiple factors, is an important index for measuring the effectiveness of agricultural water management. The purpose of this study is to promote AWP through optimally allocating limited agricultural water resources with the coordination of related elements. Firstly, the coordination effects of multiple factors related to AWP are quantified as relative optimum membership degrees based on the fuzzy optimum selecting theory. Secondly, based on the relative optimum membership degrees for various crops, a linear fractional programming model is established to maximize AWP in agricultural water resources allocation. Thirdly, the impacts of the allocation schemes on the development of social-economy and ecological environment are discussed using the multi-dimensional regulation theory. The developed integrated system has advantages in increasing agricultural water productivity through the coordination of multiple factors with aspects of economy, society and resources. Moreover, the system is capable of screening schemes considering harmonious development of resources, economy, society and ecology based on optimization results, providing decision makers with more sustainable schemes for irrigation water allocation. The integrated system including the aforementioned three parts is applied to a real-world case study in China to demonstrate its feasibility and applicability. Different water allocation schemes for various crops under different scenarios were obtained. The average value of AWP is 1.85 kg/m3, which is 0.31 kg/m3 higher than the current value of AWP. An optimum scheme with 1.1405 × 108 m3 of water being allocated was also selected due to its highest level of coordination for resources, economy, society and ecology. The developed system can provide an effective method for AWP promotion. The obtained results can help local decision makers adjust water resources allocation schemes. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Empirical Sewer Water Quality Model for Generating Influent Data for WWTP Modelling
Water 2017, 9(7), 491; doi:10.3390/w9070491
Received: 30 March 2017 / Revised: 25 June 2017 / Accepted: 30 June 2017 / Published: 5 July 2017
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Abstract
Wastewater treatment plants (WWTP) typically have a service life of several decades. During this service life, external factors, such as changes in the effluent standards or the loading of the WWTP may change, requiring WWTP performance to be optimized. WWTP modelling is widely
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Wastewater treatment plants (WWTP) typically have a service life of several decades. During this service life, external factors, such as changes in the effluent standards or the loading of the WWTP may change, requiring WWTP performance to be optimized. WWTP modelling is widely accepted as a means to assess and optimize WWTP performance. One of the challenges for WWTP modelling remains the prediction of water quality at the inlet of a WWTP. Recent applications of water quality sensors have resulted in long time series of WWTP influent quality, containing valuable information on the response of influent quality to e.g., storm events. This allows the development of empirical models to predict influent quality. This paper proposes a new approach for water quality modelling, which uses the measured hydraulic dynamics of the WWTP influent to derive the influent water quality. The model can also be based on simulated influent hydraulics as input. Possible applications of the model are filling gaps in time series used as input for WWTP models or to assess the impact of measures such as real time control (RTC) on the performance of wastewater systems. Full article
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Open AccessArticle Factor Analysis and Estimation Model of Water Consumption of Government Institutions in Taiwan
Water 2017, 9(7), 492; doi:10.3390/w9070492
Received: 8 April 2017 / Revised: 24 June 2017 / Accepted: 3 July 2017 / Published: 5 July 2017
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Abstract
Models for adequately estimating water consumption in Taiwanese government institutions were developed to assist the government to more accurately predict and account for their water needs. A correlation coefficient matrix of associated factors was constructed based on records per unit of water consumption,
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Models for adequately estimating water consumption in Taiwanese government institutions were developed to assist the government to more accurately predict and account for their water needs. A correlation coefficient matrix of associated factors was constructed based on records per unit of water consumption, describing the impact of various water consumption factors. To understand and quantify the effect of the impact factors, linear and nonlinear regression models, as well as an artificial neural network model were adopted. To account for data variability, the data used for modelling were either fully or partially adopted. For partial adoption, the quartile method was employed to remove any outliers. Analysis of the factors affecting water consumption revealed that the building floor area and number of personnel in an organization had the largest impact on estimated consumption, followed by the number of residential personnel. As the coefficient of variation for the green irrigated area and number of consulting personnel was low, the total area and the total number personnel of water consumption decreased the effectiveness of the model. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Spatiotemporal Changes of Reference Evapotranspiration in the Highest-Latitude Region of China
Water 2017, 9(7), 493; doi:10.3390/w9070493
Received: 2 June 2017 / Revised: 29 June 2017 / Accepted: 4 July 2017 / Published: 5 July 2017
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Abstract
Reference evapotranspiration (ET0) is often used to make management decisions for crop irrigation scheduling and production. In this study, the spatial and temporal trends of ET0 in China’s most northern province as well as the country’s largest agricultural region
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Reference evapotranspiration (ET0) is often used to make management decisions for crop irrigation scheduling and production. In this study, the spatial and temporal trends of ET0 in China’s most northern province as well as the country’s largest agricultural region were analyzed for the period from 1964 to 2013. ET0 was calculated with the Penman-Monteith of Food and Agriculture Organization of the United Nations irrigation and drainage paper NO.56 (FAO-56) using climatic data collected from 27 stations. Inverse distance weighting (IDW) was used for the spatial interpolation of the estimated ET0. A Modified Mann–Kendall test (MMK) was applied to test the spatiotemporal trends of ET0, while Pearson’s correlation coefficient and cross-wavelet analysis were employed to assess the factors affecting the spatiotemporal variability at different elevations. The results from this study showed a clear decreasing trend for annual ET0 from the low elevation plain area to the high elevation mountainous area. Over the past five decades, ET0 in Heilongjiang Province decreased in all seasons, except for the winter months, during which a steady increase in temperature was found. Elevation played an important role in estimating ET0 in this higher-latitude region, while relative humidity was the most relevant meteorological factor that affected the spatiotemporal variation of ET0 in the province. Overall, the findings from the study suggest that winter ET0 in a high altitude region will continue to increase in the future as climate change persists, which could worsen spring droughts and irrigation management for semi-arid areas in the province. Full article
(This article belongs to the Special Issue Adaptation Strategies to Climate Change Impacts on Water Resources)
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Open AccessArticle Robot-Assisted Measurement for Hydrologic Understanding in Data Sparse Regions
Water 2017, 9(7), 494; doi:10.3390/w9070494
Received: 28 February 2017 / Revised: 8 June 2017 / Accepted: 2 July 2017 / Published: 6 July 2017
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Abstract
This article describes the field application of small, low-cost robots for remote surface data collection and an automated workflow to support water balance computations and hydrologic understanding where water availability data is sparse. Current elevation measurement approaches, such as manual surveying and LiDAR,
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This article describes the field application of small, low-cost robots for remote surface data collection and an automated workflow to support water balance computations and hydrologic understanding where water availability data is sparse. Current elevation measurement approaches, such as manual surveying and LiDAR, are costly and infrequent, leading to potential inefficiencies for quantifying the dynamic hydrologic storage capacity of the land surface over large areas. Experiments to evaluate a team of two different robots, including an unmanned aerial vehicle (UAV) and an unmanned surface vehicle (USV), to collect hydrologic surface data utilizing sonar and visual sensors were conducted at three different field sites within the Arkavathy Basin river network located near Bangalore in Karnataka, South India. Visual sensors were used on the UAV to capture high resolution imagery for topographic characterization, and sonar sensors were deployed on the USV to capture bathymetric readings; the data streams were fused in an automated workflow to determine the storage capacity of agricultural reservoirs (also known as ``tanks'') at the three field sites. This study suggests: (i) this robot-assisted methodology is low-cost and suitable for novice users, and (ii) storage capacity data collected at previously unmapped locations revealed strong power-type relationships between surface area, stage, and storage volume, which can be incorporated into modeling of landscape-scale hydrology. This methodology is of importance to water researchers and practitioners because it produces local, high-resolution representations of bathymetry and topography and enables water balance computations at small-watershed scales, which offer insight into the present-day dynamics of a strongly human impacted watershed. Full article
(This article belongs to the Special Issue New Developments in Methods for Hydrological Process Understanding)
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Open AccessArticle Application of Multi-Step Parameter Estimation Method Based on Optimization Algorithm in Sacramento Model
Water 2017, 9(7), 495; doi:10.3390/w9070495
Received: 4 May 2017 / Revised: 24 June 2017 / Accepted: 3 July 2017 / Published: 7 July 2017
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Abstract
The Sacramento model is widely utilized in hydrological forecast, of which the accuracy and performance are primarily determined by the model parameters, indicating the key role of parameter estimation. This paper presents a multi-step parameter estimation method, which divides the parameter estimation of
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The Sacramento model is widely utilized in hydrological forecast, of which the accuracy and performance are primarily determined by the model parameters, indicating the key role of parameter estimation. This paper presents a multi-step parameter estimation method, which divides the parameter estimation of Sacramento model into three steps and realizes optimization step by step. We firstly use the immune clonal selection algorithm (ICSA) to solve the non-liner objective function of parameter estimation, and compare the parameter calibration result of ideal artificial data with Shuffled Complex Evolution (SCE-UA), Parallel Genetic Algorithm (PGA), and Serial Master-slaver Swarms Shuffling Evolution Algorithm Based on Particle Swarms Optimization (SMSE-PSO). The comparison result shows that ICSA has the best convergence, efficiency and precision. Then we apply ICSA to the parameter estimation of single-step and multi-step Sacramento model and simulate 32 floods based on application examples of Dongyang and Tantou river basins for validation. It is clearly shown that the results of multi-step method based on ICSA show higher accuracy and 100% qualified rate, indicating its higher precision and reliability, which has great potential to improve Sacramento model and hydrological forecast. Full article
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Open AccessArticle Using Probable Maximum Precipitation to Bound the Disaggregation of Rainfall
Water 2017, 9(7), 496; doi:10.3390/w9070496
Received: 8 May 2017 / Revised: 3 July 2017 / Accepted: 4 July 2017 / Published: 7 July 2017
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Abstract
The Multiplicative Discrete Random Cascade (MDRC) class of model is used to temporally disaggregate rainfall volumes through multiplying the volumes by random weights, which is repeated through multiple disaggregation levels. The model development involves the identification of probability density functions from which to
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The Multiplicative Discrete Random Cascade (MDRC) class of model is used to temporally disaggregate rainfall volumes through multiplying the volumes by random weights, which is repeated through multiple disaggregation levels. The model development involves the identification of probability density functions from which to sample the weights. The parameters of the probability density functions are known to be dependent on the rainfall volume. This paper characterises the volume dependency over the scarcely observed extreme ranges of rainfall, introducing the concept of volume-bounded MDRC models. Probable maximum precipitation (PMP) estimates are used to define theoretically-based points and asymptotes to which the observation-based estimates of the MDRC model parameters are extrapolated. Alternative models are tested using a case study of rainfall data from Brisbane, Australia covering the period 1908 to 2015. The results show that moving from a baseline model with constant parameters to incorporating the volume dependency of the parameters is essential for acceptable performance in terms of the frequency and magnitude of modelled extremes. As well as providing better estimates of parameters at each disaggregation level, the volume dependency provides an in-built bias correction when moving from one level to the next. A further, relatively small performance gain is obtained by extrapolating the observed dependency to the theoretically-based bounds. The volume dependency of the parameters is found to be reasonably time-scaleable, providing opportunity for advances in the generalisation of MDRC models. Sensitivity analysis shows that the subjectivities and uncertainties in the modelling procedure have mixed effects on the performance. A principal uncertainty, to which the results are sensitive, is the PMP estimate. Therefore, in applications of the bounded approach, the PMP should ideally be described by a probability distribution function. Full article
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Open AccessFeature PaperArticle Source Water Protection Planning and Management in Metropolitan Canada: A Preliminary Assessment
Water 2017, 9(7), 497; doi:10.3390/w9070497
Received: 26 February 2017 / Revised: 22 June 2017 / Accepted: 23 June 2017 / Published: 7 July 2017
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Abstract
Source Water Protection (SWP) is the process of protecting a drinking water source through land use planning policies and land management activities. The risk of source water contamination is a human health concern even in developed countries such as Canada. Much of the
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Source Water Protection (SWP) is the process of protecting a drinking water source through land use planning policies and land management activities. The risk of source water contamination is a human health concern even in developed countries such as Canada. Much of the existing SWP literature in the more developed world is centred on small and rural water systems with a focus on capacity needs to support SWP activities and planning. These capacity needs tend to centre on five key elements: political, financial, human, technical and legal. While these contributions have added value to the water resource planning literature in rural areas, there remains a noticeable gap in the literature with respect to SWP activities in metropolitan areas. The purpose of this paper is twofold: first, to report the kinds of source water threats facing metropolitan water systems in Canada; and, second, to explore the utility of the capacity literature with respect to SWP planning in metropolitan Canada. Full article
(This article belongs to the Special Issue Source Water Protection: State of the Art and Science)
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Open AccessArticle Efficiency of Mn Removal of Different Filtration Materials for Groundwater Treatment Linking Chemical and Physical Properties
Water 2017, 9(7), 498; doi:10.3390/w9070498
Received: 30 April 2017 / Revised: 5 June 2017 / Accepted: 23 June 2017 / Published: 8 July 2017
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Abstract
This paper presents research on Fe and Mn removal from groundwater. In treatment systems of aeration followed by rapid filtration (no chemical dosage), manganese removal is possible due to the manganese dioxide catalyst present on the grains of filtration material. The goal of
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This paper presents research on Fe and Mn removal from groundwater. In treatment systems of aeration followed by rapid filtration (no chemical dosage), manganese removal is possible due to the manganese dioxide catalyst present on the grains of filtration material. The goal of the presented research was to find a correlation between the catalyst layer’s composition as well as its internal porosity and the effectiveness and stability of manganese removal in the filtration process. In order to establish the influence of catalyst characteristics on manganese removal effectiveness, the filtration experiment was conducted using filtration materials with catalytic contact layers of different origin. Oxide coated auto-activated silica sand and Gabon manganese ore were tested. Inactive silica sand was used as reference. The results of filtration experiments were combined with analyses of chemical composition, internal porosity, and crystalline parameters of catalyst contact layers of grains. For the determination catalyst contact layer parameters, the following methods were used: Raman spectroscopy, X-ray powder diffractometry (XRD), Scanning Electron Microscope – Energy dispersive spectroscopy (SEM-EDAX), nitrogen adsorption. Pilot scale research on the filtration process demonstrated that auto-activated filtration material was characterized by the highest efficiency of manganese removal and stability of effects during the whole research. The effectiveness of Gabon manganese ore dropped from 90% and stabilized on the level of ca. 60% within 15 days of the experiment. Full article
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Open AccessArticle Actual and Reference Evapotranspiration in a Cornfield in the Zhangye Oasis, Northwestern China
Water 2017, 9(7), 499; doi:10.3390/w9070499
Received: 28 April 2017 / Revised: 28 June 2017 / Accepted: 3 July 2017 / Published: 8 July 2017
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Abstract
Evapotranspiration (ET) is an important component of the surface energy balance and water cycle, especially in arid and semiarid regions. The characteristics of the actual evapotranspiration (ETa), which was calculated using the eddy covariance method, and the reference
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Evapotranspiration (ET) is an important component of the surface energy balance and water cycle, especially in arid and semiarid regions. The characteristics of the actual evapotranspiration (ETa), which was calculated using the eddy covariance method, and the reference evapotranspiration (ET0), which was estimated using the Food and Agriculture Organisation (FAO) Penman–Monteith method, were analysed. This work focussed on the seasonal variations in evapotranspiration and crop coefficient (Kc) above the heterogeneous canopy of an arid oasis ecosystem in a cornfield of the Zhangye oasis in northwestern China. The results showed that in 2008, the total net radiation (Rn) was 2457.73 MJ∙m−2 and that the rainfall was 117 mm. The average wind velocity, air temperature, and specific humidity, which were observed 2 m above the ground surface, were 1.23 m∙s−1, 7.07 °C, and 3.66 g∙kg−1, respectively. The total ETa and ET0 were 654.69 mm and 1039.92 mm, respectively; thus, the ET0 was higher than the ETa. The difference between the ET0 and ETa was high in summer and autumn, and low in winter and spring. The ETa was greatly influenced by irrigation events, whereas the ET0 was not influenced by irrigation. The ETa and ET0 were both greatly influenced by meteorological elements. The Kc values were less than 0.5 outside of the maize-growing stage and greater than 0.5 during the entire maize-growing stage (from 20 April to 22 September 2008). The Kc values were 0.63, 0.75, 0.78, 0.76, 0.61 and 0.71 at the seedling, shooting, heading, filling, and maturity stages and the entire growth stage, respectively. Full article
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Open AccessArticle Characterization of Terrestrial Discharges into Coastal Waters with Thermal Imagery from a Hierarchical Monitoring Program
Water 2017, 9(7), 500; doi:10.3390/w9070500
Received: 13 April 2017 / Revised: 27 June 2017 / Accepted: 6 July 2017 / Published: 11 July 2017
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Abstract
Background: The hierarchical use of remotely-sensed imagery from satellites, and then proximally-sensed imagery from helicopter sand drones, can provide a range of spatial and temporal coverage that supports water quality monitoring of complex pollution scenarios. Methods: The study used hierarchical satellite-, helicopter-, and
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Background: The hierarchical use of remotely-sensed imagery from satellites, and then proximally-sensed imagery from helicopter sand drones, can provide a range of spatial and temporal coverage that supports water quality monitoring of complex pollution scenarios. Methods: The study used hierarchical satellite-, helicopter-, and drone-acquired thermal imagery of coastal plumes ranging from 3 to 300 m, near Naples, Italy, and captured temporally- and spatially-overlapping in situ samples to correlate thermal and water quality parameters in each plume and the seawater. Results: In situ sampling determined that between-plume salinity varied by 37%, chlorophyll-a varied by 356%, dissolved oxygen varied by 81%, and turbidity varied by 232%. The radiometric temperature, Trad, for the plume area of interest had a correlation of 0.81 with salinity, 0.74 with chlorophyll-a, 0.98 with dissolved oxygen, and −0.61 with turbidity. Conclusion: This study established hierarchical use of remote and proximal thermal imagery can provide monitoring of complex coastal areas. Full article
(This article belongs to the Special Issue The Use of Remote Sensing in Hydrology)
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Open AccessArticle Nutrient Leaching When Soil Is Part of Plant Growth Media
Water 2017, 9(7), 501; doi:10.3390/w9070501
Received: 14 June 2017 / Revised: 30 June 2017 / Accepted: 7 July 2017 / Published: 11 July 2017
PDF Full-text (208 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Soils can serve as sorbents for phosphorus (P), negating the need for artificial sorbents. The purpose of this study was to compare soils with different properties for their effect on nutrient levels in effluent. Four soils were mixed with sand and packed into
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Soils can serve as sorbents for phosphorus (P), negating the need for artificial sorbents. The purpose of this study was to compare soils with different properties for their effect on nutrient levels in effluent. Four soils were mixed with sand and packed into columns 0.5 m long, with or without compost on the surface. Infiltration and effluent concentrations were measured before and after growing plants [Buffalograss (Buchloe dactyloides (Nutt.) Engelm.) and bluegrama grasses (Bouteloua gracilis H.B.K.) and red clover (Trifolium pratense L.)]. The growth media with compost at the surface had higher nutrient levels than the media without the compost, but the final effluent nitrate concentrations post-harvest were significantly lower for columns with the compost blanket (59 vs. 86 mg L−1). All of the nitrate concentrations were high (many >100 mg L−1) due to mineralization and nitrogen fixation. The final effluent P concentrations before planting were significantly higher in the soil with the most sand (0.71 mg L−1), and after harvest in the mixture that contained the high soil P levels (0.58 mg L−1). Some soils (high in aluminum or calcium) were adequate sorbents for P without additions of other sorbents, but soils often generated too much nitrate in effluent. Full article
(This article belongs to the Special Issue Additives in Stormwater Filters for Enhanced Pollutant Removal)
Open AccessArticle Performance Evaluations of Three Silt Fence Practices Using a Full-Scale Testing Apparatus
Water 2017, 9(7), 502; doi:10.3390/w9070502
Received: 5 June 2017 / Revised: 5 July 2017 / Accepted: 6 July 2017 / Published: 11 July 2017
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Abstract
Erosion and sediment controls on construction sites minimize environmental impacts from sediment-laden stormwater runoff. Silt fence, a widely specified perimeter control practice on construction projects used to retain sediment on-site, has limited performance-based testing data. Silt fence failures and resultant sediment losses are
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Erosion and sediment controls on construction sites minimize environmental impacts from sediment-laden stormwater runoff. Silt fence, a widely specified perimeter control practice on construction projects used to retain sediment on-site, has limited performance-based testing data. Silt fence failures and resultant sediment losses are often the result of structural failure. To better understand silt fence performance, researchers at the Auburn University-Erosion and Sediment Control Testing Facility (AU-ESCTF) have evaluated three silt fence options to determine possible shortcomings using standardized full-scale testing methods. These methods subject silt fence practices to simulated, in-field conditions typically experienced on-site without the variability of field testing or the limited application of small-scale testing. Three different silt fence practices were tested to evaluate performance, which included: (1) Alabama Department of Transportation (ALDOT) Trenched Silt Fence, (2) ALDOT Sliced Silt Fence, and (3) Alabama Soil and Water Conservation Committee (AL-SWCC) Trenched Silt Fence. This study indicates that the structural performance of a silt fence perimeter control is the most important performance factor in retaining sediment. The sediment retention performance of these silt fence practices was 82.7%, 66.9% and 90.5%, respectively. When exposed to large impoundment conditions, both ALDOT Trench and Sliced Silt Fence practices failed structurally, while the AL-SWCC Trenched Silt Fence did not experience structural failure. Full article
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Open AccessArticle Root Development of Transplanted Cotton and Simulation of Soil Water Movement under Different Irrigation Methods
Water 2017, 9(7), 503; doi:10.3390/w9070503
Received: 29 April 2017 / Revised: 6 June 2017 / Accepted: 5 July 2017 / Published: 11 July 2017
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Abstract
Winter wheat and cotton are the main crops grown on the North China Plain (NCP). Cotton is often transplanted after the winter wheat harvest to solve the competition for cultivated land between winter wheat and cotton, and to ensure that both crops can
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Winter wheat and cotton are the main crops grown on the North China Plain (NCP). Cotton is often transplanted after the winter wheat harvest to solve the competition for cultivated land between winter wheat and cotton, and to ensure that both crops can be harvested on the NCP. However, the root system of transplanted cotton is distorted due to the restrictions of the seedling aperture disk before transplanting. Therefore, the investigation of the deformed root distribution and water uptake in transplanted cotton is essential for simulating soil water movement under different irrigation methods. Thus, a field experiment and a simulation study were conducted during 2013–2015 to explore the deformed roots of transplanted cotton and soil water movement using border irrigation (BI) and surface drip irrigation (SDI). The results showed that SDI was conducive to root growth in the shallow root zone (0–30 cm), and that BI was conducive to root growth in the deeper root zone (below 30 cm). SDI is well suited for producing the optimal soil water distribution pattern for the deformed root system of transplanted cotton, and the root system was more developed under SDI than under BI. Comparisons between experimental data and model simulations showed that the HYDRUS-2D model described the soil water content (SWC) under different irrigation methods well, with root mean square errors (RMSEs) of 0.023 and 0.029 cm3 cm−3 and model efficiencies (EFs) of 0.68 and 0.59 for BI and SDI, respectively. Our findings will be very useful for designing an optimal irrigation plan for BI and SDI in transplanted cotton fields, and for promoting the wider use of this planting pattern for cotton transplantation. Full article
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Open AccessArticle Stress and Welfare of African Catfish (Clarias gariepinus Burchell, 1822) in a Coupled Aquaponic System
Water 2017, 9(7), 504; doi:10.3390/w9070504
Received: 12 April 2017 / Revised: 3 July 2017 / Accepted: 7 July 2017 / Published: 11 July 2017
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Abstract
African catfish (Clarias gariepinus) were investigated for physiological stress parameters to assess the influence of different cultivation techniques on fish welfare. The fish were reared in two conceptually identical recirculating aquaculture systems (RAS) constructed in a greenhouse. One system was combined
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African catfish (Clarias gariepinus) were investigated for physiological stress parameters to assess the influence of different cultivation techniques on fish welfare. The fish were reared in two conceptually identical recirculating aquaculture systems (RAS) constructed in a greenhouse. One system was combined with a floating raft hydroponic unit to culture cucumbers (Cucumis sativus) only using the process water. The second system remained without the plant cultivation unit and functioned as the control. Water quality was monitored regularly by measuring dissolved nutrients and physical water parameters. During 87 days, a total of 71 fish from each system (n = 142) were studied, with a final sampling of all fish (n = 107) at the end of the experiment. Blood from the caudal vein was analyzed for the stress hormone cortisol and the glucose concentration. In addition, fish were investigated for external injuries on their skin, fins and barbels. The results demonstrate that the system design had no influence on fish mortalities and growth rates. Furthermore, cortisol and blood glucose levels did not differ significantly between the two systems. However, the number of external injuries was significantly lower in the aquaponics, providing evidence that co-cultivation of fish and plants might offer benefits to the welfare of the fish. Full article
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Open AccessArticle Spatial Variations in the Surface Water Chemistry of Subtropical Peatlands (Central China) Linked to Anthropogenic Pressures
Water 2017, 9(7), 505; doi:10.3390/w9070505
Received: 17 February 2017 / Revised: 7 July 2017 / Accepted: 7 July 2017 / Published: 11 July 2017
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Abstract
Compared with the extensively surveyed temperate and boreal peatlands, subtropical peatlands have received rather little scientific attention. In this study, spatial variations in water chemistry were investigated in 57 samples collected from three subtropical peatlands (central China). Generally, water pH and major cation
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Compared with the extensively surveyed temperate and boreal peatlands, subtropical peatlands have received rather little scientific attention. In this study, spatial variations in water chemistry were investigated in 57 samples collected from three subtropical peatlands (central China). Generally, water pH and major cation concentrations of these samples approached the characteristics of poor fens along the bog–rich fen gradient. Four distinct groups were identified by cluster analysis and principal component analysis. High concentrations of trace elements in Group I were probably linked to airborne dust pollutants from a nearby road under construction. Low pH values and low major cation concentrations in Group II may be attributed to the great cation exchange capacity of Sphagnum. In contrast, samples in Group III, mainly collected from sites suffering from Sphagnum harvest, showed high pH levels and major cation concentrations. Relatively low concentrations of trace elements (except boron) in Group IV can be regarded as reference conditions for restoration efforts in these peatlands. Taken together, spatial variations in the water chemistry of the three peatlands were closely linked to natural processes (e.g., cation exchange of Sphagnum) and anthropogenic pressures (e.g., Sphagnum harvest). Overall, the mean health risk values of the six trace elements were low, indicating good water quality in these peatlands. This study provided baseline water chemistry information for the sustainable management of these subtropical peatlands, as well as other similar ecosystems. Full article
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Open AccessArticle NF-RO Membrane Performance for Treating the Effluent of an Organized Industrial Zone Wastewater Treatment Plant: Effect of Different UF Types
Water 2017, 9(7), 506; doi:10.3390/w9070506
Received: 16 May 2017 / Revised: 12 June 2017 / Accepted: 3 July 2017 / Published: 11 July 2017
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Abstract
Reuse of water is necessary in Organized Industrial Zones (OIZ) due to excessive use of groundwater in semi-arid Turkey. Membrane treatment of the OIZ wastewater treatment plant (WWTP) effluents should be explored for new treatment options. In this study, three different UF membranes
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Reuse of water is necessary in Organized Industrial Zones (OIZ) due to excessive use of groundwater in semi-arid Turkey. Membrane treatment of the OIZ wastewater treatment plant (WWTP) effluents should be explored for new treatment options. In this study, three different UF membranes with variable molecular weight cutoff (MWCO) values (4, 10, and 250 kDa) were used to treat the effluent of an OIZ WWTP at laboratory scale. Six different nanofiltration (NF) and reverse osmosis (RO) membranes were used for the effluent of UF membranes to evaluate the difference in the membrane filtration performance and the water quality. Effluent electrical conductivity (EC) values of NF membranes were 1.77 ± 0.17, 3.73 ± 0.27, and 4.20 ± 0.23 ms/cm for NF (NF90, NF270, and TM610) membranes, respectively while they were 0.83 ± 0.47, 1.17 ± 0.47, and 1.13 ± 0.57 ms/cm for RO (XLE, AD90, and BW30) membranes, respectively. Scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDS), and confocal laser scanning microscope (CLSM) images showed severe biofouling in UF 4 kDa and UF 10 kDa membranes whereas UF 250 kDa membrane showed larger metal precipitates and little bacterial fouling. The results indicated that OIZ WWTP effluent could be reused as irrigation water according to Turkish regulations with UF 250 kDa and RO-XLE membranes, effectively. Full article
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Open AccessFeature PaperArticle A Probabilistic Short-Term Water Demand Forecasting Model Based on the Markov Chain
Water 2017, 9(7), 507; doi:10.3390/w9070507
Received: 15 May 2017 / Revised: 6 July 2017 / Accepted: 7 July 2017 / Published: 12 July 2017
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Abstract
This paper proposes a short-term water demand forecasting method based on the use of the Markov chain. This method provides estimates of future demands by calculating probabilities that the future demand value will fall within pre-assigned intervals covering the expected total variability. More
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This paper proposes a short-term water demand forecasting method based on the use of the Markov chain. This method provides estimates of future demands by calculating probabilities that the future demand value will fall within pre-assigned intervals covering the expected total variability. More specifically, two models based on homogeneous and non-homogeneous Markov chains were developed and presented. These models, together with two benchmark models (based on artificial neural network and naïve methods), were applied to three real-life case studies for the purpose of forecasting the respective water demands from 1 to 24 h ahead. The results obtained show that the model based on a homogeneous Markov chain provides more accurate short-term forecasts than the one based on a non-homogeneous Markov chain, which is in line with the artificial neural network model. Both Markov chain models enable probabilistic information regarding the stochastic demand forecast to be easily obtained. Full article
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Open AccessArticle Water Policy of Korea for Supplying Safe Groundwater in Rural Areas
Water 2017, 9(7), 508; doi:10.3390/w9070508
Received: 29 May 2017 / Revised: 5 July 2017 / Accepted: 7 July 2017 / Published: 12 July 2017
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Abstract
According to a 2015 study conducted by the Ministry of Environment of Korea, municipal water is supplied to 96.1% of the total Korean population, but 3.9% of the total population (~2.14 million people) in rural myeon or villages, drink groundwater from old and/or
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According to a 2015 study conducted by the Ministry of Environment of Korea, municipal water is supplied to 96.1% of the total Korean population, but 3.9% of the total population (~2.14 million people) in rural myeon or villages, drink groundwater from old and/or unregistered wells that are not a part of the municipal water system. Additionally, accurate statistics are not reported without regular water quality tests, so safety measures alone are insufficient to improve water quality. In this situation, the Korean government is responsible for verifying the quality of groundwater and identifying the cause of groundwater contamination in areas with no municipal water supply. The National Institute of Environmental Research (NIER) under the Ministry of Environment of Korea, conducted the ‘Safe Groundwater Supply Project (SGSP)’ between 2012 and 2016 to secure groundwater quality stability in areas without the benefit of municipal water. This survey identified groundwater quality using a detailed water quality survey and gave recommendations for supplying safe groundwater and providing future improvements and countermeasures in cases of groundwater pollution. This paper presents the SGSP and consists of water quality analysis, the exploration and exploitation of drinking water facilities, the selection of a pilot project area among high-pollution areas, and improvement measures for water quality in the pilot project area. Full article
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Open AccessArticle Assessing the Efficacy of the SWAT Auto-Irrigation Function to Simulate Irrigation, Evapotranspiration, and Crop Response to Management Strategies of the Texas High Plains
Water 2017, 9(7), 509; doi:10.3390/w9070509
Received: 26 May 2017 / Revised: 29 June 2017 / Accepted: 7 July 2017 / Published: 12 July 2017
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Abstract
In the semi-arid Texas High Plains, the underlying Ogallala Aquifer is experiencing continuing decline due to long-term pumping for irrigation with limited recharge. Accurate simulation of irrigation and other associated water balance components are critical for meaningful evaluation of the effects of irrigation
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In the semi-arid Texas High Plains, the underlying Ogallala Aquifer is experiencing continuing decline due to long-term pumping for irrigation with limited recharge. Accurate simulation of irrigation and other associated water balance components are critical for meaningful evaluation of the effects of irrigation management strategies. Modelers often employ auto-irrigation functions within models such as the Soil and Water Assessment Tool (SWAT). However, some studies have raised concerns as to whether the function is able to adequately simulate representative irrigation practices. In this study, observations of climate, irrigation, evapotranspiration (ET), leaf area index (LAI), and crop yield derived from an irrigated lysimeter field at the USDA-ARS Conservation and Production Research Laboratory at Bushland, Texas were used to evaluate the efficacy of the SWAT auto-irrigation functions. Results indicated good agreement between simulated and observed daily ET during both model calibration (2001–2005) and validation (2006–2010) periods for the baseline scenario (Nash-Sutcliffe efficiency; NSE ≥ 0.80). The auto-irrigation scenarios resulted in reasonable ET simulations under all the thresholds of soil water deficit (SWD) triggers as indicated by NSE values > 0.5. However, the auto-irrigation function did not adequately represent field practices, due to the continuation of irrigation after crop maturity and excessive irrigation when SWD triggers were less than the static irrigation amount. Full article
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Open AccessArticle Mapping Submerged Aquatic Vegetation Using RapidEye Satellite Data: The Example of Lake Kummerow (Germany)
Water 2017, 9(7), 510; doi:10.3390/w9070510
Received: 20 March 2017 / Revised: 13 June 2017 / Accepted: 5 July 2017 / Published: 12 July 2017
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Abstract
Submersed aquatic vegetation (SAV) is sensitive to changes in environmental conditions and plays an important role as a long-term indictor for the trophic state of freshwater lakes. Variations in water level height, nutrient condition, light availability and water temperature affect the growth and
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Submersed aquatic vegetation (SAV) is sensitive to changes in environmental conditions and plays an important role as a long-term indictor for the trophic state of freshwater lakes. Variations in water level height, nutrient condition, light availability and water temperature affect the growth and species composition of SAV. Detailed information about seasonal variations in littoral bottom coverage are still unknown, although these effects are expected to mask climate change-related long-term changes, as derived by snapshots of standard monitoring methods included in the European Water Framework Directive. Remote sensing offers concepts to map SAV quickly, within large areas, and at short intervals. This study analyses the potential of a semi-empirical method to map littoral bottom coverage by a multi-seasonal approach. Depth-invariant indices were calculated for four Atmospheric & Topographic Correction (ATCOR2) atmospheric corrected RapidEye data sets acquired at Lake Kummerow, Germany, between June and August 2015. RapidEye data evaluation was supported by in situ measurements of the diffuse attenuation coefficient of the water column and bottom reflectance. The processing chain was able to differentiate between SAV and sandy sediment. The successive increase of SAV coverage from June to August was correctly monitored. Comparisons with in situ and Google Earth imagery revealed medium accuracies (kappa coefficient = 0.61, overall accuracy = 72.2%). The analysed time series further revealed how water constituents and temporary surface phenomena such as sun glint or algal blooms influence the identification success of lake bottom substrates. An abundant algal bloom biased the interpretability of shallow water substrate such that a differentiation of sediments and SAV patches failed completely. Despite the documented limitations, mapping of SAV using RapidEye seems possible, even in eutrophic lakes. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle Do Consumers of Environmentally Friendly Farming Products in Downstream Areas Have a WTP for Water Quality Protection in Upstream Areas?
Water 2017, 9(7), 511; doi:10.3390/w9070511
Received: 23 February 2017 / Revised: 30 June 2017 / Accepted: 4 July 2017 / Published: 12 July 2017
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Abstract
In South Korea, the Soyang Lake is an important source of drinking water to the metropolitan areas including Seoul. However, water quality problems in the Soyang Lake have still remained due to chemical contaminations attributed to conventional farming practices in the upstream areas.
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In South Korea, the Soyang Lake is an important source of drinking water to the metropolitan areas including Seoul. However, water quality problems in the Soyang Lake have still remained due to chemical contaminations attributed to conventional farming practices in the upstream areas. Based on a downstream consumer survey using a contingent valuation method, this study estimated the expected willingness to pays (WTPs) for water quality improvement through the conversion to environmentally friendly farming (EFF). The results showed that the estimated annual mean WTP is KRW 36,115 per household. The aggregated WTPs of downstream respondents in the Soyang Lake are sufficient to compensate for the income losses of upstream EFF farmers in highland farming areas. In addition, we found that the downstream citizens who recognize the label for EFF products and who intend to purchase EFF products in the future have a significant impact on WTPs for water quality improvement. Full article
(This article belongs to the Special Issue Water Economics and Policy)
Open AccessArticle Performance and Fouling in Pre-Denitrification Membrane Bioreactors Treating High-Strength Wastewater from Food Waste Disposers
Water 2017, 9(7), 512; doi:10.3390/w9070512
Received: 24 April 2017 / Revised: 30 June 2017 / Accepted: 7 July 2017 / Published: 12 July 2017
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Abstract
The study investigated the performance of the pre-denitrification membrane bioreactor (MBR) process to treat high-strength wastewater generated from food waste disposals. Extracellular polymeric substances (EPS) as membrane foulant and microbial community profiles were analyzed under different hydraulic retention time (HRT) operation conditions. The
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The study investigated the performance of the pre-denitrification membrane bioreactor (MBR) process to treat high-strength wastewater generated from food waste disposals. Extracellular polymeric substances (EPS) as membrane foulant and microbial community profiles were analyzed under different hydraulic retention time (HRT) operation conditions. The pre-denitrification MBR was effective for treating food wastewater with high chemical oxygen demand (COD)/N resulting in high total nitrogen (TN) removal efficiency. The operational data showed that effluent qualities in terms of COD, TN, and TP improved with longer HRT. However, membrane fouling potential as shown by specific membrane fouling rate and specific resistance to filtration (SRF) increased as HRT increased. The longer HRT conditions or lower influent loading led to higher levels of bound EPS while HRT did not show large effects on the level of soluble microbial products (SMP). The restriction fragment length polymorphism (RFLP) analysis showed similar microbial banding patterns from the sludges generated under different HRT conditions, indicating that HRT had minimal effects on the composition of microbial communities in the system. All these results suggest that the MBR with pre-denitrification is a feasible option for treating high-strength food wastewater and that different HRT conditions could affect the operational performance and the fouling rate, which is governed via changes in microbial responses through EPS in the system. Full article
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Open AccessArticle Water Use of Fossil Energy Production and Supply in China
Water 2017, 9(7), 513; doi:10.3390/w9070513
Received: 31 May 2017 / Revised: 3 July 2017 / Accepted: 5 July 2017 / Published: 12 July 2017
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Abstract
Fossil energy and water resources are both important for economic and social development in China, and they are tightly interlinked. Fossil energy production consumes large amounts of water, and it is essential to investigate the water footprint of fossil energy production (WFEP
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Fossil energy and water resources are both important for economic and social development in China, and they are tightly interlinked. Fossil energy production consumes large amounts of water, and it is essential to investigate the water footprint of fossil energy production (WFEP) in China. In addition, fossil energy is supplied to consumers in China by both domestic and foreign producers, and understanding the water footprint of fossil energy supply (WFES) is also highly significant for water and energy development programs in the long-term. The objectives of this paper were to provide an estimation of the blue component of WFEP and WFES in China for the period from 2001 to 2014, and to evaluate the impact on water resources from energy production, the contribution of internal and external WFES, and water-energy related issues of the international energy trade by applying water footprint analysis based on the bottom-up approach. The results indicate that generally, the WFEP and WFES in China both maintained steady growth before 2013, with the WFEP increasing from approximately 3900 million m3/year to 10,400 million m3/year, while the WFES grew from 3900 million m3/year to 11,600 million m3/year. The fossil energy production caps of the 13th Five Year Plan can bring the water consumed for fossil energy production back to a sustainable level. Over the long-term, China’s energy trade plan should also consider the water and energy resources of the countries from which fossil energy is imported. Full article
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Open AccessFeature PaperArticle Fish but Not Macroinvertebrates Promote Trophic Cascading Effects in High Density Submersed Plant Experimental Lake Food Webs in Two Contrasting Climate Regions
Water 2017, 9(7), 514; doi:10.3390/w9070514
Received: 28 May 2017 / Revised: 27 June 2017 / Accepted: 7 July 2017 / Published: 12 July 2017
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Abstract
Predators play a key role in the functioning of shallow lakes. Differences between the response of temperate and subtropical systems to fish predation have been proposed, but experimental evidence is scarce. To elucidate cascading effects produced by predators in contrasting climatic zones, we
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Predators play a key role in the functioning of shallow lakes. Differences between the response of temperate and subtropical systems to fish predation have been proposed, but experimental evidence is scarce. To elucidate cascading effects produced by predators in contrasting climatic zones, we conducted a mesocosm experiment in three pairs of lakes in Uruguay and Denmark. We used two typical planktivorous-omnivorous fish species (Jenynsia multidentata + Cnesterodon decemmaculatus and Gasterosteus aculeatus + Perca fluviatilis) and one littoral omnivorous-predatory macroinvertebrate (Palaemonetes argentinus and Gammarus lacustris), alone and combined, in numbers resembling natural densities. Fish predation on zooplankton increased phytoplankton biomass in both climate zones, whereas the effects of predatory macroinvertebrates on zooplankton and phytoplankton were not significant in either climate zone. Macroinvertebrates (that freely colonized the sampling devices) were diminished by fish in both climate areas; however, periphyton biomass did not vary among treatments. Our experiments demonstrated that fish affected the structure of both planktonic and littoral herbivorous communities in both climate regions, with a visible positive cascading effect on phytoplankton biomass, but no effects on periphyton. Altogether, fish impacts appeared to be a strong driver of turbid water conditions in shallow lakes regardless of climatic zone by indirectly contributing to increasing phytoplankton biomass. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle Food Web Responses to Artificial Mixing in a Small Boreal Lake
Water 2017, 9(7), 515; doi:10.3390/w9070515
Received: 27 April 2017 / Revised: 27 June 2017 / Accepted: 1 July 2017 / Published: 12 July 2017
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Abstract
In order to simulate food web responses of small boreal lakes to changes in thermal stratification due to global warming, a 4 year whole-lake manipulation experiment was performed. Within that time, period lake mixing was intensified artificially during two successive summers. Complementary data
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In order to simulate food web responses of small boreal lakes to changes in thermal stratification due to global warming, a 4 year whole-lake manipulation experiment was performed. Within that time, period lake mixing was intensified artificially during two successive summers. Complementary data from a nearby lake of similar size and basic water chemistry were used as a reference. Phytoplankton biomass and chlorophyll a did not respond to the greater mixing depth but an increase was observed in the proportional abundance of diatoms, and the proportional abundance of cryptophytes also increased immediately after the onset of mixing. Obligate anoxic green sulphur bacteria vanished at the onset of mixing but gradually recovered after re-establishment of hypolimnetic anoxic conditions. No major effect on crustacean zooplankton was found, but their diversity increased in the metalimnion. During the mixing, the density of rotifers declined but protozoan density increased in the hypolimnion. Littoral benthic invertebrate density increased during the mixing due to Ephemeroptera, Asellus aquaticus and Chironomidae, whereas the density of Chaoborus larvae declined during mixing and lower densities were still recorded one year after the treatment. No structural changes in fish community were found although gillnet catches increased after the onset of the study. The early growth of perch (Perca fluviatilis) increased compared to the years before the mixing and in comparison to the reference lake, suggesting improved food availability in the experimental lake. Although several food web responses to the greater mixing depth were found, their persistence and ecological significance were strongly dependent on the extent of the disturbance. To better understand the impacts of wind stress on small lakes, long term whole-lake experiments are needed. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessFeature PaperArticle End-User Cost-Benefit Prioritization for Selecting Rainwater Harvesting and Greywater Reuse in Social Housing
Water 2017, 9(7), 516; doi:10.3390/w9070516
Received: 26 May 2017 / Revised: 1 July 2017 / Accepted: 6 July 2017 / Published: 12 July 2017
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Abstract
Rainwater harvesting (RWH) and greywater reuse (GWR) are increasingly being considered at the building-level to achieve multiple goals. Cost-benefit assessments facilitate decision-making; however, most are focused on large-scale systems with limited information available for households from developing countries. To better understand the prioritization
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Rainwater harvesting (RWH) and greywater reuse (GWR) are increasingly being considered at the building-level to achieve multiple goals. Cost-benefit assessments facilitate decision-making; however, most are focused on large-scale systems with limited information available for households from developing countries. To better understand the prioritization of costs and benefits by potential end-users in this context, this paper presents an assessment of an RWH/GWR system in low income, low consumption households in a social housing development in Colombia. From an initial household consultation, preferences related to the use of RWH/GWR were identified and three alternatives were proposed and designed. In a follow-up consultation, potential end-users were engaged with the cost-benefit of the proposed alternatives. Potential end-users prioritized the selection of the system with potable water savings of 25%, a payback period of 30 years, an internal return rate of 4.7%, and a Benefit/Cost ratio of 1.3. Of the three alternatives, this system had the median payback period, highest investment, and highest maintenance cost, but also the highest volumetric water saving and highest water and sewerage bill savings. In contrast to findings from developed countries, this indicates that minimising the cost may not be the primary decision making criteria in some developing country contexts, where perhaps a greater value is placed on conserving water resources. Full article
(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)
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Open AccessArticle Comparison of Four Nitrate Removal Kinetic Models in Two Distinct Wetland Restoration Mesocosm Systems
Water 2017, 9(7), 517; doi:10.3390/w9070517
Received: 27 April 2017 / Revised: 6 July 2017 / Accepted: 9 July 2017 / Published: 13 July 2017
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Abstract
The objective of the study was to determine the kinetic model that best fit observed nitrate removal rates at the mesocosm scale in order to determine ideal loading rates for two future wetland restorations slated to receive pulse flow agricultural drainage water. Four
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The objective of the study was to determine the kinetic model that best fit observed nitrate removal rates at the mesocosm scale in order to determine ideal loading rates for two future wetland restorations slated to receive pulse flow agricultural drainage water. Four nitrate removal models were investigated: zero order, first order decay, efficiency loss, and Monod. Wetland mesocosms were constructed using the primary soil type (in triplicate) at each of the future wetland restoration sites. Eighteen mesocosm experiments were conducted over two years across seasons. Simulated drainage water was loaded into wetlands as batches, with target nitrate-N levels typically observed in agricultural drainage water (between 2.5 and 10 mg L−1). Nitrate-N removal observed during the experiments provided the basis for calibration and validation of the models. When the predictive strength of each of the four models was assessed, results indicated that the efficiency loss and first order decay models provided the strongest agreement between predicted and measured NO3-N removal rates, and the fit between the two models were comparable. Since the predictive power of these two models were similar, the less complicated first order decay model appeared to be the best choice in predicting appropriate loading rates for the future full-scale wetland restorations. Full article
(This article belongs to the Special Issue Treatment Wetlands for Nutrient Removal)
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Open AccessArticle Positive Surge Propagation in Sloping Channels
Water 2017, 9(7), 518; doi:10.3390/w9070518
Received: 22 June 2017 / Revised: 3 July 2017 / Accepted: 9 July 2017 / Published: 13 July 2017
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Abstract
A simplified model for the upstream propagation of a positive surge in a sloping, rectangular channel is presented. The model is based on the assumptions of a flat water surface and negligible energy dissipation downstream of the surge, which is generated by the
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A simplified model for the upstream propagation of a positive surge in a sloping, rectangular channel is presented. The model is based on the assumptions of a flat water surface and negligible energy dissipation downstream of the surge, which is generated by the instantaneous closure of a downstream gate. Under these hypotheses, a set of equations that depends only on time accurately describes the surge wave propagation. When the Froude number of the incoming flow is relatively small, an approximate analytical solution is also proposed. The predictive ability of the model is validated by comparing the model results with the results of an experimental investigation and with the results of a numerical model that solves the full shallow water equations. Full article
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Open AccessArticle Optimal Combinations of Non-Sequential Regressors for ARX-Based Typhoon Inundation Forecast Models Considering Multiple Objectives
Water 2017, 9(7), 519; doi:10.3390/w9070519
Received: 19 April 2017 / Revised: 3 July 2017 / Accepted: 11 July 2017 / Published: 14 July 2017
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Abstract
Inundation forecast models with non-sequential regressors are advantageous in efficiency due to their rather fewer input variables required to be processed. This type of model is nevertheless rare mainly because of the difficulty in finding the proper combination of regressors for the model
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Inundation forecast models with non-sequential regressors are advantageous in efficiency due to their rather fewer input variables required to be processed. This type of model is nevertheless rare mainly because of the difficulty in finding the proper combination of regressors for the model to perform accurate prediction. A novel methodology is proposed in this study to tackle the problem. The approach involves integrating a Multi-Objective Genetic Algorithm (MOGA) with forecast models based on ARX (Auto-Regressive model with eXogenous inputs) to transfer the search for the optimal combination of non-sequential regressors into an optimization problem. An innovative approach to codifying any combinations of model regressors into binary strings is developed and employed in MOGA. The Pareto optimal sets of three types of models including linear ARX (LARX), nonlinear ARX with Wavelet function (NLARX-W), and nonlinear ARX with Sigmoid function (NLARX-S) are searched for by the proposed methodology. The results show that the optimal models acquired through this approach have good inundation forecasting capabilities in every aspect in terms of accuracy, time shift error, and error distribution. Full article
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Open AccessArticle Modelling Dissolved Oxygen Depression in an Urban River in China
Water 2017, 9(7), 520; doi:10.3390/w9070520
Received: 31 May 2017 / Revised: 9 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
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Abstract
Dissolved oxygen (DO) depression in urban rivers appears to be increasing in developing countries, which causes severe aquatic ecosystem stresses. One urban river which suffers DO depression under low flow conditions and requires systematic research for effective mitigation strategies is the Nanfei River
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Dissolved oxygen (DO) depression in urban rivers appears to be increasing in developing countries, which causes severe aquatic ecosystem stresses. One urban river which suffers DO depression under low flow conditions and requires systematic research for effective mitigation strategies is the Nanfei River (Hefei, China). We investigated its longitudinal profiles of DO and other related water constituents with high spatial resolution monitoring at low flow. A mechanistic DO model for the reach was customized and calibrated with the data obtained. We found that the daily average DO levels within the 11 km study reach shifted from supersaturation (11.5 mg L−1) upstream of the Wangtang Wastewater Treatment Plant (WWTP) to serious depletion (3.6 mg L−1) downstream. Process analysis indicated that DO production via strong algal photosynthesis overwhelmed the DO consumptions upstream from the WWTP. In contrast, DO sources could not compensate for DO consumptions, wherein carbonaceous deoxygenation was the largest consumer of the DO (approximately 70%) downstream the WWTP. Rather than directly contributing labile organics, the WWTP effluent affected the DO balance by shifting the metabolism from upstream autotrophy to downstream heterotrophy. Finally, mitigation strategies for DO depression in rivers in rapidly-urbanizing regions were suggested accordingly. Full article
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Open AccessArticle An Examination of Soil Moisture Estimation Using Ground Penetrating Radar in Desert Steppe
Water 2017, 9(7), 521; doi:10.3390/w9070521
Received: 5 May 2017 / Revised: 3 July 2017 / Accepted: 10 July 2017 / Published: 22 July 2017
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Abstract
Ground penetrating radar (GPR) is a new technique of rapid soil moisture measurement, which is an important approach to measure soil moisture at the intermediate scale. To test the applicability of GPR method for soil moisture in desert steppe, we used the common-mid
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Ground penetrating radar (GPR) is a new technique of rapid soil moisture measurement, which is an important approach to measure soil moisture at the intermediate scale. To test the applicability of GPR method for soil moisture in desert steppe, we used the common-mid point (CMP) method and fixed offset (FO) method to evaluate the influence factors and the accuracy of GPR measurement with gravimetric soil moisture measurements. The experiments showed that Topp’s equation is more suitable than Roth’s equation for processing the GPR data in desert steppe and the soil moisture measurements by GPR had high accuracy by either CMP method or FO method. To a certain extent, the vegetation coverage affects the measurement precision and the soil moisture profile. The precipitation can reduce the effective sampling depth of the ground wave from 0.1 m to 0.05 m. The results revealed that GPR has the advantages of high measurement accuracy, easy movement, simple operation, and no damage to the soil layer structure. Full article
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Open AccessArticle Spatial Variation of Sea Level Rise at Atlantic and Mediterranean Coastline of Europe
Water 2017, 9(7), 522; doi:10.3390/w9070522
Received: 26 June 2017 / Accepted: 11 July 2017 / Published: 14 July 2017
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Abstract
The inundation impact of sea level rise (SLR) is critical, since coastal regions of Europe house important critical infrastructures and large population centers. According to International Panel on Climate Change (IPCC) studies, the analysis of the SLR problem is complicated. Beyond the reported
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The inundation impact of sea level rise (SLR) is critical, since coastal regions of Europe house important critical infrastructures and large population centers. According to International Panel on Climate Change (IPCC) studies, the analysis of the SLR problem is complicated. Beyond the reported complexities involved in the analysis of this phenomenon, the expected spatial variability of SLR in oceans further complicates this analysis. Spatial variability of SLR in oceans is both observed and also expected, according to IPCC studies. Estimation of spatial variation of SLR in oceans is necessary to identify the level of potential threats that may impact different coastline regions. Identification of geographic patterns of SLR based on local coastal data has been reported in the literature. Unfortunately, these estimates cannot be used in predictive analysis over a century. Thus, the solution of this problem using mathematical models is the other alternative that can be employed. Modeling solutions to this problem is currently in its infancy, and further studies in this field are needed. In this study, a methodology developed by the authors is used to estimate the SLR for the Atlantic and the Mediterranean coastline of Europe that also includes the other oceans. This effort utilizes the dynamic system model (DSM) with spatial analysis capability (S-DSM) to predict the regional sea level change. Results obtained provide consistent assessment of spatial variability of SLR pattern in oceans as well as the temperature changes over the 21st century. This approach may also be used in other coastal regions to aid management decision in a timely manner. Full article
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Open AccessArticle Flood Effect on Groundwater Recharge on a Typical Silt Loam Soil
Water 2017, 9(7), 523; doi:10.3390/w9070523
Received: 30 March 2017 / Revised: 1 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
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Abstract
Floods are of great concern as the global climate changes, and investigations of flood water infiltration and groundwater recharge are important for water resource management worldwide, especially under conditions of global climate changes. However, information on the relationship between the flood water and
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Floods are of great concern as the global climate changes, and investigations of flood water infiltration and groundwater recharge are important for water resource management worldwide, especially under conditions of global climate changes. However, information on the relationship between the flood water and groundwater recharge is limited. The objective of this study was to determine the relationship between the flood water depth and the height of groundwater rise using lysimeters and numerical modeling in the floodplain of the Tarim River in northwestern China. The experimental results suggested that the rise in height of the groundwater table was closely related to the flood water ponding depth, and the groundwater depth decreased quickly after flooding due to the high infiltration rate of water originating at the Tarim River. The water table falling velocity was significantly less than the water table rising velocity. If the initial groundwater table was deeper, the variation in the water table rise depth was smaller and the water table falling velocity was slower. The numerical simulation results showed good agreement with the observed data, with a determination coefficient (R2) of 0.87 and a root mean square error (RMSE) of 63.91 cm. A good relationship (R2 = 0.789) between the initial groundwater table depth (H0), initial soil water content (W0), flood water depth (h), and height of the water table rise (H) was established. Considering that natural and artificial flood frequencies are related to flood time interval (dt), a relationship (R2 = 0.892) was developed between them. These results can enhance the understanding of flood recharge characteristics in the floodplains of inland rivers. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessArticle Chlorophyll-A Prediction of Lakes with Different Water Quality Patterns in China Based on Hybrid Neural Networks
Water 2017, 9(7), 524; doi:10.3390/w9070524
Received: 25 May 2017 / Revised: 12 July 2017 / Accepted: 13 July 2017 / Published: 14 July 2017
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Abstract
One of the most important water quality problems affecting lakes and reservoirs is eutrophication, which is caused by multiple physical and chemical factors. As a representative index of eutrophication, the concentration of chlorophyll-a has always been a key indicator monitored by environmental managers.
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One of the most important water quality problems affecting lakes and reservoirs is eutrophication, which is caused by multiple physical and chemical factors. As a representative index of eutrophication, the concentration of chlorophyll-a has always been a key indicator monitored by environmental managers. The most influential factors on chlorophyll-a may be dependent on the different water quality patterns in lakes. In this study, data collected from 27 lakes in different provinces of China during 2009–2011 were analyzed. The self-organizing map (SOM) was first applied on the datasets and the lakes were classified into four clusters according to 24 water quality parameters. Comparison amongst the clusters revealed that Cluster I was the least polluted and at the lowest trophic level, while Cluster IV was the most polluted and at the highest trophic level. The genetic algorithm optimized back-propagation neural network (GA-BPNN) was applied to each lake cluster to select the most influential input variables for chlorophyll-a. The results of the four clusters showed that the performance of GA-BPNN was satisfied with nearly half of the input variables selected from the predictor pool. The selected factors varied for the lakes in different clusters, which indicates that the control for eutrophication should be separate for lakes in different provinces of one country. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle River Stage Modeling by Combining Maximal Overlap Discrete Wavelet Transform, Support Vector Machines and Genetic Algorithm
Water 2017, 9(7), 525; doi:10.3390/w9070525
Received: 21 May 2017 / Revised: 3 July 2017 / Accepted: 5 July 2017 / Published: 15 July 2017
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Abstract
This paper proposes a river stage modeling approach combining maximal overlap discrete wavelet transform (MODWT), support vector machines (SVMs) and genetic algorithm (GA). The MODWT decomposes original river stage time series into sub-time series (detail and approximation components). The SVM computes daily river
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This paper proposes a river stage modeling approach combining maximal overlap discrete wavelet transform (MODWT), support vector machines (SVMs) and genetic algorithm (GA). The MODWT decomposes original river stage time series into sub-time series (detail and approximation components). The SVM computes daily river stage values using the decomposed sub-time series. The GA searches for the optimal hyperparameters of SVM. The performance of MODWT–SVM models is evaluated using efficiency and effectiveness indices; and compared with that of a single model (multilayer perceptron (MLP) and SVM), discrete wavelet transform (DWT)-based models (DWT–MLP and DWT–SVM) and MODWT–MLP models. The conjunction of MODWT, SVM and GA improves the performance of the SVM model and outperforms the single models. The MODWT–based models using the SVM model enhance model performance and accuracy compared to those of using MLP model. Also, hybrid models coupling MODWT, SVM and GA improve model performance and accuracy in daily river stage modeling as compared with those combined with DWT. The MODWT–SVM model using the Coiflet 12 (c12) mother wavelet, MODWT–SVM-c12, produces the best efficiency and effectiveness among all models. Therefore, the conjunction of MODWT, SVM and GA can be an efficient and effective approach for modeling daily river stages. Full article
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Open AccessArticle Field Studies of Microbial Removal from Stormwater by Bioretention Cells with Fly-Ash Amendment
Water 2017, 9(7), 526; doi:10.3390/w9070526
Received: 15 May 2017 / Revised: 7 July 2017 / Accepted: 13 July 2017 / Published: 15 July 2017
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Abstract
Microbial pollution in stormwater is a concern in urban areas across the U.S. and is a leading cause of water-quality impairment in the United States. This issue may be addressed through the use of best management practices (BMPs) and target limits for pathogenic
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Microbial pollution in stormwater is a concern in urban areas across the U.S. and is a leading cause of water-quality impairment in the United States. This issue may be addressed through the use of best management practices (BMPs) and target limits for pathogenic indicator species. Bioretention is a commonly used low impact development strategy that addresses this growing pollution problem at the source. Bioretention removal efficiencies have been well studied when considering nutrients and heavy metals, but field-scale treatment data are limited for microbial indicators. The primary objective of this study was to quantify microbial removal by installed bioretention cells with fly-ash amended soils. Three bioretention cells in Grove, Oklahoma were monitored over one and a half years and the removal microbial efficiency was quantified. Overall, removal rates for E. coli, enterococci, and coliphage were highly variable, with mean and standard deviations for removals for each site respectively: E. coli 87%, 35%, and 43%; enterococci 97%, 95%, and 80%; and coliphage 38%, 75%, and 32%. The site with negative removal efficiency appears to have some groundwater intrusion during storm events. Based on this relatively limited data set, these fly-ash amended bioretention cells performed 49% better than those with a sand-only filter media layer currently reported in the literature. Based on this initial field study, it appears that fly-ash amended bioretention cells may be a viable option for enhanced microbial removal from stormwater runoff. Full article
(This article belongs to the Special Issue Additives in Stormwater Filters for Enhanced Pollutant Removal)
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Open AccessArticle Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)
Water 2017, 9(7), 527; doi:10.3390/w9070527
Received: 28 April 2017 / Revised: 29 June 2017 / Accepted: 12 July 2017 / Published: 15 July 2017
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Abstract
Submerged macrophytes are important structural components of freshwater ecosystems that are widely used as long-term bioindicators for the trophic state of freshwater lakes. Climate change and related rising water temperatures are suspected to affect macrophyte growth and species composition as well as the
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Submerged macrophytes are important structural components of freshwater ecosystems that are widely used as long-term bioindicators for the trophic state of freshwater lakes. Climate change and related rising water temperatures are suspected to affect macrophyte growth and species composition as well as the length of the growing season. Alternative to the traditional ground-based monitoring methods, remote sensing is expected to provide fast and effective tools to map submerged macrophytes at short intervals and over large areas. This study analyses interrelations between spectral signature, plant phenology and the length of growing season as influenced by the variable water temperature. During the growing seasons of 2011 and 2015, remote sensing reflectance spectra of macrophytes and sediment were collected systematically in-situ with hyperspectral underwater spectroradiometer at Lake Starnberg, Germany. The established spectral libraries were used to develop reflectance models. The combination of spectral information and phenologic characteristics allows the development of a phenologic fingerprint for each macrophyte species. By inversion, the reflectance models deliver day and daytime specific spectral signatures of the macrophyte populations. The subsequent classification processing chain allowed distinguishing species-specific macrophyte growth at different phenologic stages. The analysis of spectral signatures within the phenologic development indicates that the invasive species Elodea nuttallii is less affected by water temperature oscillations than the native species Chara spp. and Potamogeton perfoliatus. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle An Integrated Method for Interval Multi-Objective Planning of a Water Resource System in the Eastern Part of Handan
Water 2017, 9(7), 528; doi:10.3390/w9070528
Received: 9 May 2017 / Revised: 28 June 2017 / Accepted: 12 July 2017 / Published: 16 July 2017
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Abstract
In this study, an integrated solving method is proposed for interval multi-objective planning. The proposed method is based on fuzzy linear programming and an interactive two-step method. It cannot only provide objectively optimal values for multiple objectives at the same time, but also
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In this study, an integrated solving method is proposed for interval multi-objective planning. The proposed method is based on fuzzy linear programming and an interactive two-step method. It cannot only provide objectively optimal values for multiple objectives at the same time, but also effectively offer a globally optimal interval solution. Meanwhile, the degree of satisfaction related to different objective functions would be obtained. Then, the integrated solving method for interval multi-objective planning is applied to a case study of planning multi-water resources joint scheduling under uncertainty in the eastern part of Handan, China. The solutions obtained are useful for decision makers in easing the contradiction between supply of multi-water resources and demand from different water users. Moreover, it can provide the optimal comprehensive benefits of economy, society, and the environment. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Sediment Size Effects in Acoustic Doppler Velocimeter-Derived Estimates of Suspended Sediment Concentration
Water 2017, 9(7), 529; doi:10.3390/w9070529
Received: 16 June 2017 / Revised: 11 July 2017 / Accepted: 11 July 2017 / Published: 16 July 2017
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Abstract
Backscatter output from a 10 MHz acoustic Doppler velocimeter (ADV) was used to quantify suspended sediment concentrations in a laboratory setting using sand-sized particles. The experiments included (a) well-sorted sand samples ranging in size from 0.112 to 0.420 mm, obtained by the sieving
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Backscatter output from a 10 MHz acoustic Doppler velocimeter (ADV) was used to quantify suspended sediment concentrations in a laboratory setting using sand-sized particles. The experiments included (a) well-sorted sand samples ranging in size from 0.112 to 0.420 mm, obtained by the sieving of construction sand, (b) different, known mixtures of these well-sorted fractions, and (c) sieved natural beach sand with median sizes ranging from 0.112 to 0.325 mm. The tested concentrations ranged from 25 to 3000 mg•L−1. The backscatter output was empirically related to concentration and sediment size, and when non-dimensionalized by acoustic wavelength, a dimensionless sediment size gradation coefficient. Size-dependent upper and lower bounds on measurable concentrations were also established empirically. The range of measurable conditions is broad enough to make the approach useful for sand sizes and concentrations commonly encountered in nature. A new method is proposed to determine concentrations in cases of mixed-size sediment suspensions when only calibration data for well-sorted constituent sands are available. This approach could potentially allow better estimates when the suspended load is derived from but is not fully representative of the bed material, and when the size characteristics of the suspended material are varying in time over the period of interest. Differences in results between the construction and beach sands suggest that sediment shape may also need to be considered, and point to the importance of calibrating to sediments encountered at the site of interest. Full article
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Open AccessArticle Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils
Water 2017, 9(7), 531; doi:10.3390/w9070531
Received: 2 June 2017 / Revised: 11 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
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Abstract
In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P) into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were
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In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P) into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP), soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss. Full article
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Open AccessArticle Total Discharge Estimation in the Korean Peninsula Using Multi-Satellite Products
Water 2017, 9(7), 532; doi:10.3390/w9070532
Received: 26 May 2017 / Revised: 12 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
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Abstract
Estimation of total discharge is necessary to understand the hydrological cycle and to manage water resources efficiently. However, the task is problematic in an area where ground observations are limited. The North Korea region is one example. Here, the total discharge was estimated
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Estimation of total discharge is necessary to understand the hydrological cycle and to manage water resources efficiently. However, the task is problematic in an area where ground observations are limited. The North Korea region is one example. Here, the total discharge was estimated based on the water balance using multiple satellite products. They are the terrestrial water storage changes (TWSC) derived from the Gravity Recovery and Climate Experiment (GRACE), precipitation from the Tropical Rainfall Measuring Mission (TRMM), and evapotranspiration from the Moderate Resolution Imaging Spectroradiometer (MODIS). The satellite-based discharge was compared with land surface model products of the Global Land Data Assimilation System (GLDAS), and a positive relationship between the results was obtained (r = 0.70–0.86; bias = −9.08–16.99 mm/month; RMSE = 36.90–62.56 mm/month; NSE = 0.01–0.62). Among the four land surface models of GLDAS (CLM, Mosaic, Noah, and VIC), CLM corresponded best with the satellite-based discharge, satellite-based discharge has a tendency to slightly overestimate compared to model-based discharge (CLM, Mosaic, Noah, and VIC) in the dry season. Also, the total discharge data based on the Precipitation-Runoff Modeling System (PRMS) and the in situ discharge for major five river basins in South Korea show comparable seasonality and high correlation with the satellite-based discharge. In spite of the relatively low spatial resolution of GRACE, and loss of information incurred during the process of integrating three different satellite products, the proposed methodology can be a practical tool to estimate the total discharge with reasonable accuracy, especially in a region with scarce hydrologic data. Full article
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Open AccessArticle The Limits of Water Pricing in a Developing Country Metropolis: Empirical Lessons from an Industrial City of Pakistan
Water 2017, 9(7), 533; doi:10.3390/w9070533
Received: 10 May 2017 / Revised: 9 July 2017 / Accepted: 14 July 2017 / Published: 18 July 2017
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Abstract
This paper seeks to question the effectiveness of water pricing as a means of consumer behavioural change in urban centres of the Global South by analysing the domestic usage for water in a major industrial city of Pakistan. Using survey data of 1100
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This paper seeks to question the effectiveness of water pricing as a means of consumer behavioural change in urban centres of the Global South by analysing the domestic usage for water in a major industrial city of Pakistan. Using survey data of 1100 households from Faisalabad city, we estimate the price and income elasticities of water demand. Instrumental variable methods are applied to overcome the endogeneity issues of water pricing. The findings reflect that price and income elasticities vary across different groups. Price elasticities range from −0.43 to −0.71, and income elasticities vary between 0.01 and 0.12. These findings suggest that pricing policies may have limited scope to drive households’ water consumption patterns. However, these empirics may suggest that policy makers should design an appropriate tariff structure to increase revenues that can be invested to further improve the existing water infrastructure. The study findings also suggest that non-pricing instruments, such as water saving campaigns, may be helpful in driving an efficient use of water in rapidly growing cities in the developing world. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Membrane Bioreactor-Based Wastewater Treatment Plant in Saudi Arabia: Reduction of Viral Diversity, Load, and Infectious Capacity
Water 2017, 9(7), 534; doi:10.3390/w9070534
Received: 5 June 2017 / Revised: 2 July 2017 / Accepted: 8 July 2017 / Published: 17 July 2017
Cited by 1 | PDF Full-text (4475 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A membrane bioreactor (MBR)-based wastewater treatment plant in Saudi Arabia was assessed over a nine-month period for virus removal efficiency. Viral diversity was detected using omics-based approaches. Log reduction values (LRV) of Adenoviruses (AdV) and Enteroviruses (EV) were enumerated using digital polymerase chain
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A membrane bioreactor (MBR)-based wastewater treatment plant in Saudi Arabia was assessed over a nine-month period for virus removal efficiency. Viral diversity was detected using omics-based approaches. Log reduction values (LRV) of Adenoviruses (AdV) and Enteroviruses (EV) were enumerated using digital polymerase chain reaction (dPCR) and assessed for infectivity using fluorescence-based infection assays. MBR treatment was successful in reducing viral diversity. Plant viruses remained abundant in the treated effluent. Human enteric viruses were present in lower abundance than plant viruses, and were reduced by MBR at varying LRV. AdV copy numbers were reduced by 3.7-log. Infectious AdV was not detected in the effluent. EV copy numbers were reduced by 1.7-log post MBR and infectious EV decreased by an average of 2.0-log. Infectious EV was detected in the chlorinated effluent, occasionally in concentrations that approximate to its 50% infectious dose. Overall, results indicated that a MBR-based wastewater treatment plant (WWTP) effectively reduces viral diversity, viral load, and infectious capacity by up to 4-logs. These findings suggest potential concerns associated with plant and human enteric viruses for reuse events in this country. Local guidelines for assessment of treated water quality should take into consideration both infectious viral concentration and LRV. Full article
(This article belongs to the Special Issue Sustainable Water Supply through Desalination and Wastewater Reuse)
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Open AccessArticle Using Ostrom’s DPs as Fuzzy Sets to Analyse How Water Policies Challenge Community-Based Water Governance in Colombia
Water 2017, 9(7), 535; doi:10.3390/w9070535
Received: 16 May 2017 / Revised: 2 July 2017 / Accepted: 13 July 2017 / Published: 18 July 2017
PDF Full-text (1226 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ostrom’s design principles have been broadly used to analyse the governance of common pool resources. However, they are normally assessed as present or absent. We challenge this assumption by considering them as fuzzy sets where membership scores range from 0 to 1, because,
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Ostrom’s design principles have been broadly used to analyse the governance of common pool resources. However, they are normally assessed as present or absent. We challenge this assumption by considering them as fuzzy sets where membership scores range from 0 to 1, because, in real situations, the design principles can be present at a certain level. We define categories to assess the level of membership and apply it to a single case study analysing how changes in water policy can affect the community-based management of the Water User Association of Mondomo (Colombia). In rural areas of Colombia, most water and sanitation services are provided by water user associations, wherein civil society has developed governance systems based on active citizen involvement and community-based management. Some of these associations have been operating for decades and are essential pillars of the local social fabric. However, recent changes in the country’s policy and legal framework threaten these long-lasting governance systems. The results show that most of the design principles would suffer important changes that undermine the governance system. Essential principles for sustainable community-based governance, such as the congruence of the rules with local conditions, the local monitoring and sanctioning capacities, the internal conflict-resolution mechanisms and the recognition of the rights to organize, are dramatically reduced after the policy implementation. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle HYDRUS Simulation of Sustainable Brackish Water Irrigation in a Winter Wheat-Summer Maize Rotation System in the North China Plain
Water 2017, 9(7), 536; doi:10.3390/w9070536
Received: 5 May 2017 / Revised: 5 July 2017 / Accepted: 11 July 2017 / Published: 18 July 2017
PDF Full-text (4431 KB) | HTML Full-text | XML Full-text
Abstract
Freshwater resources in the North China Plain (NCP) are near depletion due to the unceasing overexploitation of deep groundwater, by far the most significant source of freshwater in the region. To deal with the deepening freshwater crisis, brackish water (rich but largely unused
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Freshwater resources in the North China Plain (NCP) are near depletion due to the unceasing overexploitation of deep groundwater, by far the most significant source of freshwater in the region. To deal with the deepening freshwater crisis, brackish water (rich but largely unused water in agriculture) is increasingly being used in irrigation in the region. However, inappropriate irrigation with brackish water could lead to soil salinization and cropland degradation. To evaluate such negative impacts, the HYDRUS-1D model was used to simulate soil salt transport and accumulation under 15 years of irrigation with brackish water. The irrigation scenarios included brackish water irrigation during the wintering and jointing stages of winter wheat and then freshwater irrigation just before the sowing of summer maize. Freshwater irrigation was done to leach out soil salts, which is particularly vital in dry years. For the littoral region of the plain, HYDRUS-ID was used to simulate the irrigated cropping system stated above for a total period of 15 years. The results showed that it was feasible to use brackish water twice in one year, provided freshwater irrigation was performed before sowing summer maize. Freshwater irrigation, in conjunction with precipitation, leached out soil salts from the 100 cm root-zone depth. The maximum salt accumulation was in the 160–220 cm soil layer, which ensured that root-zone soil was free of restrictive salinity for crop growth. Precipitation was a critical determinant of the rate and depth leaching of soil salt. Heavy rainfall (>100 mm) caused significant leaching of soluble salts in the 0–200 cm soil profile. Salt concentration under brackish water irrigation had no significant effect on the variations in the trend of soil salt transport in the soil profile. The variations of soil salinity were mainly affected by hydrological year type, for which the buried depth of soil salt was higher in wet years than in dry years. The study suggested that 15 years of irrigation with brackish water is a reliable and feasible mode of crop production in coastal regions with a thick soil column above the water table. The scheme proposed in this study allowed the use of brackish water in irrigation without undue salinization of the crop soil layer, an intuitive way of resolving the deepening water crisis in the NCP study area and beyond. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessArticle Phosphorus Dynamics along River Continuum during Typhoon Storm Events
Water 2017, 9(7), 537; doi:10.3390/w9070537
Received: 11 February 2017 / Revised: 10 July 2017 / Accepted: 14 July 2017 / Published: 18 July 2017
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Abstract
Information on riverine phosphorus (P) dynamics during typhoon storm events remains scarce in subtropical regions. Thus, this study investigates the spatial and temporal dynamics of riverine phosphorus in a headwater catchment during three typhoon events. Continuous sampling (3 h intervals) of stormwater samples
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Information on riverine phosphorus (P) dynamics during typhoon storm events remains scarce in subtropical regions. Thus, this study investigates the spatial and temporal dynamics of riverine phosphorus in a headwater catchment during three typhoon events. Continuous sampling (3 h intervals) of stormwater samples and discharge data were conducted at five locations, which represent the upstream, transitional zone, and downstream areas of the main inflow river. The results revealed that the average event mean concentrations (EMCs) for total dissolved phosphorus (TDP) and particulate phosphorus (PP) in the upstream catchment of Fei-Tsui reservoir were 15.66 μg/L and 11.94 μg/L, respectively. There was at least a 1.3-fold increase in flow-weighted concentrations of TDP and PP from the upper to lower reaches of the main stream. PP and TDP were transported either in clockwise or anticlockwise directions, depending on storm intensity and source. The transport of TDP was primarily regulated by the subsurface flow during the storm event. Soluble reactive phosphorus (SRP) contributes more than 50% of the TDP load in moderate storms, while extreme storms supply a greater dissolved organic phosphorus (DOP) load into the stream. TDP accounted for approximately 50% of TP load during typhoon storms. Mobilization of all P forms was observed from upstream to downstream of the river, except for DOP. A decrease of DOP load on passing downstream may reflect the change in phosphorus form along the river continuum. Peak discharge and antecedent dry days are correlated positively with P fluxes, indicating that river bank erosion and re-suspension of within-channel sediment are the dominant pathways of P during typhoon storm periods. Full article
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Open AccessArticle Ontario’s Clean Water Act and Capacity Building: Implications for Serviced Rural Municipalities
Water 2017, 9(7), 538; doi:10.3390/w9070538
Received: 25 April 2017 / Revised: 7 July 2017 / Accepted: 10 July 2017 / Published: 18 July 2017
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Abstract
This research explores Ontario’s Clean Water Act (S.O. 2006, c. 22) and its contribution to capacity building for rural municipalities impacted by source protection plans created under the Act. Source water protection (SWP) under the Clean Water Act (S.O. 2006, c. 22)
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This research explores Ontario’s Clean Water Act (S.O. 2006, c. 22) and its contribution to capacity building for rural municipalities impacted by source protection plans created under the Act. Source water protection (SWP) under the Clean Water Act (S.O. 2006, c. 22) is explored drawing from a capacity framework. A nested case study approach has been employed to allow for in depth exploration of the experience within the Cataraqui Source Protection Area and the North Bay-Mattawa Source Protection Area, where key informant interviews were conducted. Findings are outlined looking at four elements of capacity for SWP: institutional, financial, social, and technical/human. It was found that the process was successful for building capacity in the serviced rural municipalities involved, but did not provide any meaningful protection for areas reliant on private drinking water systems such as wells. Several improvements to the legislated process were suggested including greater flexibility for local circumstance and better methods for engagement of First Nations and the general public. It is unknown if this capacity will be sustained as the program continues and provincial funding is reduced. Reduced funding will particularly impact rural communities that lack the internal human and financial capacity to implement SWP policies without the assistance of provincial funding and conservation authority staff (who also rely on provincial/municipal funding sources). Ultimately, it was found that SWP in rural areas requires enforceable mandatory legislation; sustainable provincial funding and municipal fiscal frameworks to support ongoing SWP planning and implementation; technical aid at the regional level; and support and commitment to SWP at the local level (e.g., municipalities, local health units, landowners, residents and watershed users). Full article
(This article belongs to the Special Issue Source Water Protection: State of the Art and Science)
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Open AccessArticle Carbon Dioxide Emissions from the Littoral Zone of a Chinese Reservoir
Water 2017, 9(7), 539; doi:10.3390/w9070539
Received: 3 May 2017 / Revised: 10 July 2017 / Accepted: 14 July 2017 / Published: 19 July 2017
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Abstract
The continuous increase in the number of reservoirs globally has raised important questions about the environmental impact of their greenhouse gases emissions. In particular, the littoral zone may be a hotspot for production of greenhouse gases. We investigated the spatiotemporal variation of CO
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The continuous increase in the number of reservoirs globally has raised important questions about the environmental impact of their greenhouse gases emissions. In particular, the littoral zone may be a hotspot for production of greenhouse gases. We investigated the spatiotemporal variation of CO2 flux at the littoral zone of a Chinese reservoir along a wet-to-dry transect from permanently flooded land, seasonally flooded land to non-flooded dry land, using the static dark chamber technique. The mean total CO2 emission was 346 mg m−2 h−1 and the rate varied significantly by water levels, months and time of day. The spatiotemporal variation of flux was highly correlated with biomass, temperature and water level. Flooding could play a positive role in carbon balance if water recession occurs at the time when carbon gains associated with plant growth overcomes the carbon loss of ecosystem. The overall carbon balance was analysed using cumulative greenhouse gases fluxes and biomass, bringing the data of the present study alongside previously published, simultaneously measured CH4 and N2O fluxes. For the growing season, 12.8 g C m−2 was absorbed by the littoral zone. Taking CH4 and N2O into the calculation showed that permanently flooded sites were a source of greenhouse gases, rather than a sink. Our study emphasises how water level fluctuation influenced CO2, CH4 and N2O in different ways, which greatly affected the spatiotemporal variation and emission rate of greenhouse gases from the littoral zone. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle Characterisation of Hydrological Response to Rainfall at Multi Spatio-Temporal Scales in Savannas of Semi-Arid Australia
Water 2017, 9(7), 540; doi:10.3390/w9070540
Received: 30 March 2017 / Revised: 13 July 2017 / Accepted: 14 July 2017 / Published: 19 July 2017
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Abstract
Rainfall is the main driver of hydrological processes in dryland environments and characterising the rainfall variability and processes of runoff generation are critical for understanding ecosystem function of catchments. Using remote sensing and in situ data sets, we assess the spatial and temporal
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Rainfall is the main driver of hydrological processes in dryland environments and characterising the rainfall variability and processes of runoff generation are critical for understanding ecosystem function of catchments. Using remote sensing and in situ data sets, we assess the spatial and temporal variability of the rainfall, rainfall–runoff response, and effects on runoff coefficients of antecedent soil moisture and ground cover at different spatial scales. This analysis was undertaken in the Upper Burdekin catchment, northeast Australia, which is a major contributor of sediment and nutrients to the Great Barrier Reef. The high temporal and spatial variability of rainfall are found to exert significant controls on runoff generation processes. Rainfall amount and intensity are the primary runoff controls, and runoff coefficients for wet antecedent conditions were higher than for dry conditions. The majority of runoff occurred via surface runoff generation mechanisms, with subsurface runoff likely contributing little runoff due to the intense nature of rainfall events. MODIS monthly ground cover data showed better results in distinguishing effects of ground cover on runoff that Landsat-derived seasonal ground cover data. We conclude that in the range of moderate to large catchments (193–36,260 km2) runoff generation processes are sensitive to both antecedent soil moisture and ground cover. A higher runoff–ground cover correlation in drier months with sparse ground cover highlighted the critical role of cover at the onset of the wet season (driest period) and how runoff generation is more sensitive to cover in drier months than in wetter months. The monthly water balance analysis indicates that runoff generation in wetter months (January and February) is partially influenced by saturation overland flow, most likely confined to saturated soils in riparian corridors, swales, and areas of shallow soil. By March and continuing through October, the soil “bucket” progressively empties by evapotranspiration, and Hortonian overland flow becomes the dominant, if not exclusive, flow generation process. The results of this study can be used to better understand the rainfall–runoff relationships in dryland environments and subsequent exposure of coral reef ecosystems in Australia and elsewhere to terrestrial runoff. Full article
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