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Water, Volume 8, Issue 5 (May 2016) – 47 articles

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1777 KiB  
Article
Opening the Black Box: Using a Hydrological Model to Link Stakeholder Engagement with Groundwater Management
by Susanna Eden, Sharon B. Megdal, Eylon Shamir, Karletta Chief and Kelly Mott Lacroix
Water 2016, 8(5), 216; https://doi.org/10.3390/w8050216 - 23 May 2016
Cited by 30 | Viewed by 8924
Abstract
Stakeholder participation is a foundation of good water governance. Good groundwater governance typically involves the co-production of knowledge about the groundwater system. Models provide a vehicle for producing this knowledge, as well as a “boundary object” around which scientists and stakeholders can convene [...] Read more.
Stakeholder participation is a foundation of good water governance. Good groundwater governance typically involves the co-production of knowledge about the groundwater system. Models provide a vehicle for producing this knowledge, as well as a “boundary object” around which scientists and stakeholders can convene the co-production process. Through co-production, stakeholders and scientific experts can engage in exchanges that create system knowledge not otherwise achievable. The process involves one-way transfer of information, active two-way conversations, and integration of multiple kinds of knowledge into shared understanding. In the Upper Santa Cruz River basin in Arizona, USA, the University of Arizona Water Resources Research Center (WRRC) convened a project aimed at providing scientific underpinnings for groundwater planning and management. This project, entitled Groundwater, Climate, and Stakeholder Engagement, serves as a case study employing the first two stages of knowledge co-production using a hydrological model. Through an iterative process that included two-way communication, stakeholders provided critical input to hydrologic modeling analyses. Acting as a bridging organization, the WRRC facilitated a co-production process, involving location-specific and transferability workshops, which resulted in new knowledge and capacity for applying the model to novel problems. Full article
(This article belongs to the Special Issue Water Governance, Stakeholder Engagement, and Sustainable Water Resources Management)
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3372 KiB  
Article
Frequency Analysis of High Flow Extremes in the Yingluoxia Watershed in Northwest China
by Zhanling Li, Yuehua Wang, Wei Zhao, Zongxue Xu and Zhanjie Li
Water 2016, 8(5), 215; https://doi.org/10.3390/w8050215 - 21 May 2016
Cited by 8 | Viewed by 5483
Abstract
Statistical modeling of hydrological extremes is significant to the construction of hydraulic engineering. This paper, taking the Yingluoxia watershed as the study area, compares the annual maximum (AM) series and the peaks over a threshold (POT) series in order to study the hydrological [...] Read more.
Statistical modeling of hydrological extremes is significant to the construction of hydraulic engineering. This paper, taking the Yingluoxia watershed as the study area, compares the annual maximum (AM) series and the peaks over a threshold (POT) series in order to study the hydrological extremes, examines the stationarity and independence assumptions for the two series, and discusses the estimations and uncertainties of return levels from the two series using the Generalized Extreme Value (GEV) and Generalized Pareto distribution (GPD) models. For comparison, the return levels from all threshold excesses with considering the extremal index are also estimated. For the POT series, the threshold is selected by examining the mean excess plot and the stability of the parameter estimates and by using common-sense. The serial correlation is reduced by filtering out a set of dependent threshold excesses. Results show that both series are approximately stationary and independent. The GEV model fits the AM series well and the GPD model fits the POT series well. The estimated return levels are fairly comparable for the AM series, the POT series, and all threshold excesses with considering the extremal index, with the difference being less than 10% for return periods longer than 10 years. The uncertainties of the estimated return levels are the highest for the AM series, and next for the POT series and then for all threshold excesses series in turn. Full article
(This article belongs to the Special Issue Tackling Complex Water Problems in China under Changing Environment)
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1572 KiB  
Article
The Contribution of the Type of Detergent to Domestic Laundry Graywater Composition and Its Effect on Treatment Performance
by Miguel Ángel López Zavala and Eunice Espinoza Estrada
Water 2016, 8(5), 214; https://doi.org/10.3390/w8050214 - 20 May 2016
Cited by 14 | Viewed by 7161
Abstract
In this study, the contribution of liquid and powder detergents to the composition of domestic laundry graywater was evaluated. Dosages recommended by the manufacturers were used to prepare detergent solutions and generate laundry graywater. Solutions and graywater were characterized in terms of total [...] Read more.
In this study, the contribution of liquid and powder detergents to the composition of domestic laundry graywater was evaluated. Dosages recommended by the manufacturers were used to prepare detergent solutions and generate laundry graywater. Solutions and graywater were characterized in terms of total solids (TS), total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), and concentration of Linear Alkylbenzene Sulfonates (LAS’s). Additionally, the effect of the type of detergent on the treatment performance was also assessed. The coagulation–flocculation process was selected as a potential alternative for treating domestic laundry graywater. Treatment performance was assessed based on the removals of TS, TSS, TDS, turbidity, COD, and electrical conductivity (EC). Optimum coagulant dosages and mixing conditions for flocculation were determined. The results indicate a differential contribution of the type of detergent to the domestic laundry graywater composition. Liquid detergents contributed with more COD and TOC and fewer solids and LAS’s, in comparison with powder detergents. Soiled clothes increased the solids and organic loads of laundry graywater; furthermore, the laundry process reduced the LAS concentration of graywater by 77% for the liquid detergent and 47% for the powder detergent. On the other hand, the coagulation–flocculation process was more effective in treating powder detergent graywater even though the liquid detergent graywater was less polluted. Removal efficiencies on the order of 95% for turbidity and 75% for TSS were achieved for powder detergent graywater; meanwhile, for liquid detergent graywater, the removals were 73% for turbidity and 51% for TSS. Full article
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6831 KiB  
Article
Water Availability of São Francisco River Basin Based on a Space-Borne Geodetic Sensor
by Tengke Sun, Vagner G. Ferreira, Xiufeng He and Samuel A. Andam-Akorful
Water 2016, 8(5), 213; https://doi.org/10.3390/w8050213 - 20 May 2016
Cited by 49 | Viewed by 7552
Abstract
Brazil has recently experienced one of its worst droughts in the last 80 years, with wide-ranging consequences for water supply restrictions, energy rationing, and agricultural losses. Northeast and Southeast Brazil, which share the São Francisco River basin (SFRB), have experienced serious precipitation reduction [...] Read more.
Brazil has recently experienced one of its worst droughts in the last 80 years, with wide-ranging consequences for water supply restrictions, energy rationing, and agricultural losses. Northeast and Southeast Brazil, which share the São Francisco River basin (SFRB), have experienced serious precipitation reduction since 2011. We used terrestrial water-storage (TWS) fields, inverted from the Gravity Recovery and Climate Experiment (GRACE) mission measurements, to assess and quantify the ongoing drought over the SFRB. We found a water loss rate of 3.30 km3/year over the time-span of April 2002 to March 2015. In addition, the TWS drought index (TWSDI) showed the extension of the recent drought that has jeopardized the SFRB since January 2012, and which reached its maximum in July 2015 (the end of TWS time series). In this sense there seems to be a linkage between the TWSDI (wetness/dryness) and the El Niño Southern Oscillation (ENSO), in terms of the wavelet coherence, at the semi-annual and biennial bands, suggesting a relationship between the two. While acknowledging that further investigation is needed, we believe that our findings should contribute to the water management policies by quantifying the impact of this drought event over the SFRB. Full article
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2837 KiB  
Article
Bed Evolution under Rapidly Varying Flows by a New Method for Wave Speed Estimation
by Khawar Rehman and Yong-Sik Cho
Water 2016, 8(5), 212; https://doi.org/10.3390/w8050212 - 20 May 2016
Cited by 5 | Viewed by 5281
Abstract
This paper proposes a sediment-transport model based on coupled Saint-Venant and Exner equations. A finite volume method of Godunov type with predictor-corrector steps is used to solve a set of coupled equations. An efficient combination of approximate Riemann solvers is proposed to compute [...] Read more.
This paper proposes a sediment-transport model based on coupled Saint-Venant and Exner equations. A finite volume method of Godunov type with predictor-corrector steps is used to solve a set of coupled equations. An efficient combination of approximate Riemann solvers is proposed to compute fluxes associated with sediment-laden flow. In addition, a new method is proposed for computing the water depth and velocity values along the shear wave. This method ensures smooth solutions, even for flows with high discontinuities, and on domains with highly distorted grids. The numerical model is tested for channel aggradation on a sloping bottom, dam-break cases at flume-scale and reach-scale with flat bottom configurations and varying downstream water depths. The proposed model is tested for predicting the position of hydraulic jump, wave front propagation, and for predicting magnitude of bed erosion. The comparison between results based on the proposed scheme and analytical, experimental, and published numerical results shows good agreement. Sensitivity analysis shows that the model is computationally efficient and virtually independent of mesh refinement. Full article
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4739 KiB  
Article
Performance of an Underground Stormwater Detention Chamber and Comparison with Stormwater Management Ponds
by Jennifer Drake, Dean Young and Nicholas McIntosh
Water 2016, 8(5), 211; https://doi.org/10.3390/w8050211 - 20 May 2016
Cited by 13 | Viewed by 7743
Abstract
The transportation of pollutants from impervious surfaces during runoff events to receiving water bodies is a serious environmental problem. Summer runoff is also heated by impervious surfaces, causing thermal enrichment in receiving water body systems and degradation of coldwater aquatic ecosystems. End-of-pipe stormwater [...] Read more.
The transportation of pollutants from impervious surfaces during runoff events to receiving water bodies is a serious environmental problem. Summer runoff is also heated by impervious surfaces, causing thermal enrichment in receiving water body systems and degradation of coldwater aquatic ecosystems. End-of-pipe stormwater management facilities that are open to the environment can result in further elevated temperatures due to exposure to solar radiation. Receiving water systems that provide coldwater habitat require cool water temperatures to sustain healthy conditions for cold water flora and fauna (e.g., trout, dace). Underground Stormwater Detention Chambers (USDC) are a technology for the detention and treatment of stormwater runoff that can potentially solve the thermal issues associated with sun-exposed detention facilities while still providing an equivalent level of treatment services for stormwater pollutants. A field study of an USDC located in Southern Ontario was undertaken to characterize its treatment performance and effect on water temperature. The results were: the USDC was found to provide similar levels of stormwater treatment as wet detention ponds. On average, outlet maximum temperatures were 5 °C cooler than inlet maximum temperatures, and outlet water temperatures remained within the thermal regime for coldwater fish habitat throughout the evaluation period. There was little to no stratification of temperature, nor dissolved solids, but stratification of dissolved oxygen was observed mid-winter and into the spring. Full article
(This article belongs to the Special Issue BMP Development, Implementation, and Performance)
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1095 KiB  
Article
Water Governance Decentralisation and River Basin Management Reforms in Hierarchical Systems: Do They Work for Water Treatment Policy in Mexico’s Tlaxcala Atoyac Sub-Basin?
by Cesar Casiano Flores, Vera Vikolainen and Hans Bressers
Water 2016, 8(5), 210; https://doi.org/10.3390/w8050210 - 19 May 2016
Cited by 24 | Viewed by 8710
Abstract
In the last decades, policy reforms, new instruments development, and economic resources investment have taken place in water sanitation in Mexico; however, the intended goals have not been accomplished. The percentage of treated wastewater as intended in the last two federal water plans [...] Read more.
In the last decades, policy reforms, new instruments development, and economic resources investment have taken place in water sanitation in Mexico; however, the intended goals have not been accomplished. The percentage of treated wastewater as intended in the last two federal water plans has not been achieved. The creation of River Basin Commissions and the decentralisation process have also faced challenges. In the case of Tlaxcala, the River Basin Commission exists only on paper and the municipalities do not have the resources to fulfil the water treatment responsibilities transferred to them. This lack of results poses the question whether the context was sufficiently considered when the reforms were enacted. In this research, we will study the Tlaxcala Atoyac sub-basin, where water treatment policy reforms have taken place recently with a more context sensitive approach. We will apply the Governance Assessment Tool in order to find out whether the last reforms are indeed apt for the context. The Governance Assessment Tool includes four qualities, namely extent, coherence, flexibility, and intensity. The assessment allows deeper understanding of the governance context. Data collection involved semi-structured in-depth interviews with stakeholders. The research concludes that the observed combination of qualities creates a governance context that partially supports the implementation of the policy. This has helped to increase the percentage of wastewater treated, but the water quality goals set by the River Classification have not been achieved. With the last reforms, in this hierarchical context, decreasing the participation of municipal government levels has been shown to be instrumental for improving water treatment plants implementation policy, although many challenges remain to be addressed. Full article
(This article belongs to the Special Issue Water Governance, Stakeholder Engagement, and Sustainable Water Resources Management)
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6473 KiB  
Article
Generation of Natural Runoff Monthly Series at Ungauged Sites Using a Regional Regressive Model
by Dario Pumo, Francesco Viola and Leonardo Valerio Noto
Water 2016, 8(5), 209; https://doi.org/10.3390/w8050209 - 18 May 2016
Cited by 20 | Viewed by 5612
Abstract
Many hydrologic applications require reliable estimates of runoff in river basins to face the widespread lack of data, both in time and in space. A regional method for the reconstruction of monthly runoff series is here developed and applied to Sicily (Italy). A [...] Read more.
Many hydrologic applications require reliable estimates of runoff in river basins to face the widespread lack of data, both in time and in space. A regional method for the reconstruction of monthly runoff series is here developed and applied to Sicily (Italy). A simple modeling structure is adopted, consisting of a regression-based rainfall–runoff model with four model parameters, calibrated through a two-step procedure. Monthly runoff estimates are based on precipitation, temperature, and exploiting the autocorrelation with runoff at the previous month. Model parameters are assessed by specific regional equations as a function of easily measurable physical and climate basin descriptors. The first calibration step is aimed at the identification of a set of parameters optimizing model performances at the level of single basin. Such “optimal” sets are used at the second step, part of a regional regression analysis, to establish the regional equations for model parameters assessment as a function of basin attributes. All the gauged watersheds across the region have been analyzed, selecting 53 basins for model calibration and using the other six basins exclusively for validation. Performances, quantitatively evaluated by different statistical indexes, demonstrate relevant model ability in reproducing the observed hydrological time-series at both the monthly and coarser time resolutions. The methodology, which is easily transferable to other arid and semi-arid areas, provides a reliable tool for filling/reconstructing runoff time series at any gauged or ungauged basin of a region. Full article
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3322 KiB  
Article
Impacts of Floods on Organic Carbon Concentrations in Alluvial Soils along Hydrological Gradients Using a Digital Elevation Model (DEM)
by Diane Saint-Laurent, Roxane Paradis, Ariane Drouin and Vernhar Gervais-Beaulac
Water 2016, 8(5), 208; https://doi.org/10.3390/w8050208 - 18 May 2016
Cited by 21 | Viewed by 6504
Abstract
This study examines the spatial distribution of the organic carbon found in alluvial soils affected by successive floods. In flood zones, very little is known of the processes associated with the development of soils subjected to frequent flooding, in particular with respect to [...] Read more.
This study examines the spatial distribution of the organic carbon found in alluvial soils affected by successive floods. In flood zones, very little is known of the processes associated with the development of soils subjected to frequent flooding, in particular with respect to the accumulation of litter and organic carbon concentrations. The aim of this study is to better understand the distribution of organic carbon based on various hydrological gradients associated with flood recurrence. A digital elevation model was developed from LIDAR data to assess the microtopography of the site, and further delineate floodplains and no-flood zones. Various soil properties were considered in addition to organic carbon, such as pH, soil bulk density, litter, drainage, and topographic levels (elevation). The results show that the soils in the frequent-flood zones (FFz, recurrence of 0–20 years) have significantly less total organic carbon than the soils in the no-flood zones (NFz) and the moderate flood zones (MFz, 20–100 years). Average values obtained for the surface horizons (0–20 cm) vary by 1.74% ± 0.85% (FFz), 3.34% ± 1.09% (MFz) and 3.54% ± 1.77% (NFz), respectively. The absence of ground litter in the frequent flood zones helps decrease the input of organic matter in the surface horizons and progressively results in soil depletion. Full article
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6253 KiB  
Article
Groundwater Origins and Circulation Patterns Based on Isotopes in Challapampa Aquifer, Bolivia
by Etzar Gómez, Gerhard Barmen and Jan-Erik Rosberg
Water 2016, 8(5), 207; https://doi.org/10.3390/w8050207 - 18 May 2016
Cited by 9 | Viewed by 7086
Abstract
Aridity and seasonality of precipitation are characteristics of the highland region in Bolivia. Groundwater becomes an important and safe source of water when surficial bodies are intermittent and affected by natural and anthropogenic contamination. Decades of exploitation of the Challapampa aquifer, combined with [...] Read more.
Aridity and seasonality of precipitation are characteristics of the highland region in Bolivia. Groundwater becomes an important and safe source of water when surficial bodies are intermittent and affected by natural and anthropogenic contamination. Decades of exploitation of the Challapampa aquifer, combined with lack of information required to understand the groundwater circulation, represent a challenge for reservoir management. This study analyzes isotopic compositions of deuterium and oxygen-18 in different stages in the hydrologic cycle to assess flow patterns in the aquifer, especially in the alluvial fan of River Paria, where records are more extensive in space and time. Interpretations are based on existing and new data. Some implications, such as the age of water, the evaporation effect in groundwater and some thermal intrusions are supported by stable isotopes, tritium, radiocarbon, and electrical conductivity records. New results confirm that modern precipitation over the mountains surrounding the study area is the most important origin of water for shallow aquifers until exploited depths, 100 m below surface. The origin of water in deeper depths, 400 m, seems related to infiltration at higher altitudes and longer residence times. Full article
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3864 KiB  
Article
Hydro-Meteorological Drought Projections into the 21-st Century for Selected Polish Catchments
by Hadush K. Meresa, Marzena Osuch and Renata Romanowicz
Water 2016, 8(5), 206; https://doi.org/10.3390/w8050206 - 17 May 2016
Cited by 64 | Viewed by 7560
Abstract
The nature of drought conditions is estimated using a range of indices describing different aspects of drought events. Three drought indices are evaluated, namely the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Runoff Index (SRI), using observed hydroclimatic data [...] Read more.
The nature of drought conditions is estimated using a range of indices describing different aspects of drought events. Three drought indices are evaluated, namely the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Runoff Index (SRI), using observed hydroclimatic data and applying them to hydro-meteorological projections into the 21st century. The first two indices are evaluated using only meteorological variables and from this point of view, are better suited to meteorological drought projections than the third index, SRI, which is based on catchment discharge and represents hydrological drought. We assess information contained in those indices and their suitability to catchment scale climate projection drought assessment in ten selected Polish catchments, representing different hydro-climatic conditions, which are used as a case study. Projections of climatic variables (precipitation and temperature) are obtained from the EURO-CORDEX initiative derived from seven climate models at a grid resolution of 12.5 km for the time period 1971–2100. Future runoff projections for the catchments are obtained using a conceptual rainfall-runoff model (HBV). The results of analyses of indices based on observations in the reference period show consistent estimates for most of the catchments. Hydro-meteorological climate model projections for three periods, including the reference period 1971–2000, and two 30-year periods, near-future 2021–2050 and far-future 2071–2100, are used to estimate changes of future drought conditions in the catchments studied. The results show a substantial variation of temporal drought patterns over the catchments and their dependence on projected precipitation and temperature variables and the type of indices applied. Of the three indices studied, only SPEI projections indicate drier conditions in the catchments in the far-future period. The other two indices, SPI and SRI, indicate wetter climates in the future. Full article
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4084 KiB  
Article
Hydrological Evaluation of Lake Chad Basin Using Space Borne and Hydrological Model Observations
by Willibroad Gabila Buma, Sang-Il Lee and Jae Young Seo
Water 2016, 8(5), 205; https://doi.org/10.3390/w8050205 - 17 May 2016
Cited by 38 | Viewed by 10565
Abstract
Sustainable water resource management requires the assessment of hydrological changes in response to climate fluctuations and anthropogenic activities in any given area. A quantitative estimation of water balance entities is important to understand the variations within a basin. Water resources in remote areas [...] Read more.
Sustainable water resource management requires the assessment of hydrological changes in response to climate fluctuations and anthropogenic activities in any given area. A quantitative estimation of water balance entities is important to understand the variations within a basin. Water resources in remote areas with little infrastructure and technological knowhow suffer from poor documentation, rendering water management difficult and unreliable. This study analyzes the changes in the hydrological behavior of the Lake Chad basin with extreme climatic and environmental conditions that hinder the collection of field observations. Total water storage (TWS) from the Gravity Recovery and Climate Experiment (GRACE), lake level variations from satellite altimetry, and water fluxes and soil moisture from Global Land Data Assimilation System (GLDAS) were used to study the spatiotemporal variability of the hydrological parameters of the Lake Chad basin. The estimated TWS varies in a similar pattern as the lake water level. TWS in the basin area is governed by the lake’s surface water. The subsurface water volume changes were derived by combining the altimetric lake volume with the TWS over the drainage basin. The results were compared with groundwater outputs from WaterGAP Global Hydrology Model (WGHM), with both showing a somewhat similar pattern. These results could provide an insight to the availability of water resources in the Lake Chad basin for current and future management purposes. Full article
(This article belongs to the Special Issue Water Resource Variability and Climate Change)
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1790 KiB  
Article
Stakeholder Engagement for Inclusive Water Governance: “Practicing What We Preach” with the OECD Water Governance Initiative
by Aziza Akhmouch and Delphine Clavreul
Water 2016, 8(5), 204; https://doi.org/10.3390/w8050204 - 16 May 2016
Cited by 99 | Viewed by 33550
Abstract
A cursory glance at the literature on water governance reveals that stakeholder engagement has long been considered an integral part of sound governance processes. However, a closer look at the literature reveals that, beyond this general assertion, there is a lack of evidence-based [...] Read more.
A cursory glance at the literature on water governance reveals that stakeholder engagement has long been considered an integral part of sound governance processes. However, a closer look at the literature reveals that, beyond this general assertion, there is a lack of evidence-based assessment on how engagement processes contribute to water governance objectives. This article addresses this research gap by presenting key findings and policy guidance from a study by the Organisation for Economic Co-operation and Development (OECD) on “Stakeholder Engagement for Inclusive Water Governance”. This study employed comprehensive methods, including a survey administered to 215 stakeholder groups worldwide and separately, 69 case studies of specific stakeholder engagement initiatives on water management. This article also shares the experiences and lessons that have emerged from engaging stakeholders in the OECD Water Governance Initiative—an international multi-stakeholder policy forum created in 2013 to share policy and practical experiences on water governance at different levels. We hope this research will be used to stimulate and enrich discussions about the necessary conditions for results-oriented stakeholder engagement, and to guide decision makers accordingly. Full article
(This article belongs to the Special Issue Water Governance, Stakeholder Engagement, and Sustainable Water Resources Management)
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1863 KiB  
Article
Combination of Assessment Indicators for Policy Support on Water Scarcity and Pollution Mitigation
by Wei Yang, Junnian Song, Yoshiro Higano and Jie Tang
Water 2016, 8(5), 203; https://doi.org/10.3390/w8050203 - 16 May 2016
Cited by 5 | Viewed by 4980
Abstract
Given increasing concern about seeking solutions to water scarcity and pollution (WSP), this paper is intent on developing significant assessment indicators as decision variables for providing reference for policy proposals on the mitigation of WSP. An indicator package consisting of footprints of freshwater [...] Read more.
Given increasing concern about seeking solutions to water scarcity and pollution (WSP), this paper is intent on developing significant assessment indicators as decision variables for providing reference for policy proposals on the mitigation of WSP. An indicator package consisting of footprints of freshwater consumption (FC) and water pollutant discharge (WPD), virtual contents of freshwater and water pollutants, and inter-sectoral linkages in terms of industrial production, FC and WPD has been newly set up based on an extended input-output model. These indicators allow to provide specific and well-structured analysis on FC, WPD and the economy as well as their implicated interrelationships. The Source Region of Liao River located in northeastern China was selected as an empirical study area to apply the indicator package. The results indicate that farming and production of electricity industries are major contributors to FC; farming and breeding industries, and households are major contributors to WPD. The study area exports a large amount of net virtual total nitrogen, total phosphorus and chemical oxygen demand (29.01 × 103 t, 4.66 × 103 t, 60.38 × 103 t, respectively). Farming and breeding industries are the sectors whose production could be constrained to contribute to mitigating WSP without excessive negative impacts on the economy. Two categories of policies have been proposed to mitigate WSP based on the analysis of the indicator package. One is to introduce direct water pollutant treatment and water-saving policies to the target sectors; the other is to adjust industrial structure. The integrated indicator package developed and the methodology presented are expected to provide policy researchers and decision makers with references for more sound water management. Full article
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5195 KiB  
Article
Using High-Resolution Data to Test Parameter Sensitivity of the Distributed Hydrological Model HydroGeoSphere
by Thomas Cornelissen, Bernd Diekkrüger and Heye R. Bogena
Water 2016, 8(5), 202; https://doi.org/10.3390/w8050202 - 16 May 2016
Cited by 25 | Viewed by 7729
Abstract
Parameterization of physically based and distributed hydrological models for mesoscale catchments remains challenging because the commonly available data base is insufficient for calibration. In this paper, we parameterize a mesoscale catchment for the distributed model HydroGeoSphere by transferring evapotranspiration parameters calibrated at a [...] Read more.
Parameterization of physically based and distributed hydrological models for mesoscale catchments remains challenging because the commonly available data base is insufficient for calibration. In this paper, we parameterize a mesoscale catchment for the distributed model HydroGeoSphere by transferring evapotranspiration parameters calibrated at a highly-equipped headwater catchment in addition to literature data. Based on this parameterization, the sensitivity of the mesoscale catchment to spatial variability in land use, potential evapotranspiration and precipitation and of the headwater catchment to mesoscale soil and land use data was conducted. Simulations of the mesoscale catchment with transferred parameters reproduced daily discharge dynamics and monthly evapotranspiration of grassland, deciduous and coniferous vegetation in a satisfactory manner. Precipitation was the most sensitive input data with respect to total runoff and peak flow rates, while simulated evapotranspiration components and patterns were most sensitive to spatially distributed land use parameterization. At the headwater catchment, coarse soil data resulted in a change in runoff generating processes based on the interplay between higher wetness prior to a rainfall event, enhanced groundwater level rise and accordingly, lower transpiration rates. Our results indicate that the direct transfer of parameters is a promising method to benefit highly equipped simulations of the headwater catchments. Full article
(This article belongs to the Special Issue Hillslope and Watershed Hydrology)
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6537 KiB  
Article
Open, Sharable, and Extensible Data Management for the Korea National Aquatic Ecological Monitoring and Assessment Program: A RESTful API-Based Approach
by Meilan Jiang, Karpjoo Jeong, Jung-Hwan Park, Nan-Young Kim, Soon-Jin Hwang and Sang-Hun Kim
Water 2016, 8(5), 201; https://doi.org/10.3390/w8050201 - 13 May 2016
Cited by 3 | Viewed by 6249
Abstract
Implemented by a national law, the National Aquatic Ecological Monitoring Program (NAEMP) has been assessing the ecological health status of surface waters, focusing on streams and rivers, in Korea since 2007. The program involves ecological monitoring of multiple aquatic biota such as benthic [...] Read more.
Implemented by a national law, the National Aquatic Ecological Monitoring Program (NAEMP) has been assessing the ecological health status of surface waters, focusing on streams and rivers, in Korea since 2007. The program involves ecological monitoring of multiple aquatic biota such as benthic diatoms, macroinvertebrates, fish, and plants as well as water quality and habitat parameters. Taking advantage of the national scale of long-term aquatic ecological monitoring and the standardization of protocols and methods, the datasets in NAEMP provide many opportunities for various advanced comparative and synthetic studies, policy-making, and ecological management. In order to realize these potentials and opportunities, we have developed a RESTful API-based data management system called OSAEM (the Open, Sharable and Extensible Data Management System for Aquatic Ecological Monitoring), which is designed to be open, sharable, and extensible. In this paper, we introduce the RESTful API-based data management approach, present the RESTful API for the OSAEM system, and discuss its applicability. An OSAEM prototype system is currently available on a commercial cloud service (Amazon EC2) but the system remains under active development. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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10461 KiB  
Article
The FLO Diffusive 1D-2D Model for Simulation of River Flooding
by Costanza Aricò, Pasquale Filianoti, Marco Sinagra and Tullio Tucciarelli
Water 2016, 8(5), 200; https://doi.org/10.3390/w8050200 - 13 May 2016
Cited by 19 | Viewed by 7262
Abstract
An integrated 1D-2D model for the solution of the diffusive approximation of the shallow water equations, named FLO, is proposed in the present paper. Governing equations are solved using the MArching in Space and Time (MAST) approach. The 2D floodplain domain is discretized [...] Read more.
An integrated 1D-2D model for the solution of the diffusive approximation of the shallow water equations, named FLO, is proposed in the present paper. Governing equations are solved using the MArching in Space and Time (MAST) approach. The 2D floodplain domain is discretized using a triangular mesh, and standard river sections are used for modeling 1D flow inside the section width occurring with low or standard discharges. 1D elements, inside the 1D domain, are quadrilaterals bounded by the trace of two consecutive sections and by the sides connecting their extreme points. The water level is assumed to vary linearly inside each quadrilateral along the flow direction, but to remain constant along the direction normal to the flow. The computational cell can share zero, one or two nodes with triangles of the 2D domain when lateral coupling occurs and more than two nodes in the case of frontal coupling, if the corresponding section is at one end of the 1D channel. No boundary condition at the transition between the 1D-2D domain has to be solved, and no additional variable has to be introduced. Discontinuities arising between 1D and 2D domains at 1D sections with a top width smaller than the trace of the section are properly solved without any special restriction on the time step. Full article
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2902 KiB  
Article
A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi-) Arid Regions
by Ammar Adham, Michel Riksen, Mohamed Ouessar and Coen J. Ritsema
Water 2016, 8(5), 198; https://doi.org/10.3390/w8050198 - 13 May 2016
Cited by 74 | Viewed by 28175
Abstract
Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for [...] Read more.
Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi-) arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP) supported by the Geographic Information System (GIS). Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia) in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites. Full article
(This article belongs to the Special Issue Rainwater Harvesting: Quantity, Quality, Economics and State Regulations)
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1258 KiB  
Review
Coliphages as Model Organisms in the Characterization and Management of Water Resources
by Juan Jofre, Francisco Lucena, Anicet R. Blanch and Maite Muniesa
Water 2016, 8(5), 199; https://doi.org/10.3390/w8050199 - 12 May 2016
Cited by 96 | Viewed by 22636
Abstract
Two groups of bacteriophages that infect Escherichia coli, somatic and F-specific coliphages, have been used in academia as both fecal and viral indicators for many years. Regulatory authorities in different parts of the world are beginning to consider coliphages as indicators of [...] Read more.
Two groups of bacteriophages that infect Escherichia coli, somatic and F-specific coliphages, have been used in academia as both fecal and viral indicators for many years. Regulatory authorities in different parts of the world are beginning to consider coliphages as indicators of water quality in a range of settings. However, issues such as their potential replication in natural water environments, the cumbersome detection and enumeration methods, a lack of definition concerning which of the two groups should be included in future regulations, and the lack of a clear correlation between coliphages and human viruses and health risks in different water settings remain controversial. This review attempts to shed some light on these contentious issues. The conclusions are that: 1) supposing that they can replicate in some natural water settings, the contribution of coliphages replicated outside the gut will not affect the numbers contributed by fecal pollution and detected by strains recommended for standardized methods; 2) there are easy, fast, and cost-effective methods that can be used in routine laboratories after a little training; 3) perhaps the best option is to determine both groups in a single step; and 4) the low correlation of coliphages with human viruses and health risks is no worse than the correlation between different human viruses. Full article
(This article belongs to the Special Issue Pathogens in Water)
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1700 KiB  
Article
Discussion on the Choice of Decomposition Level for Wavelet Based Hydrological Time Series Modeling
by Moyuan Yang, Yan-Fang Sang, Changming Liu and Zhonggen Wang
Water 2016, 8(5), 197; https://doi.org/10.3390/w8050197 - 12 May 2016
Cited by 51 | Viewed by 5849
Abstract
The combination of wavelet analysis methods with data-driven models is a prevalent approach to conducting hydrological time series forecasting, but the results are affected by the accuracy of the wavelet decomposition of the series. The choice of decomposition level is one of the [...] Read more.
The combination of wavelet analysis methods with data-driven models is a prevalent approach to conducting hydrological time series forecasting, but the results are affected by the accuracy of the wavelet decomposition of the series. The choice of decomposition level is one of the key factors for the wavelet decomposition. In this paper, the data of daily precipitation and streamflow time series measured in the upper reach of the Heihe River Basin in Northwest China were used as an example, and the influence of the decomposition level on wavelet-based hydrological time series forecasting was investigated. The true components of the precipitation series were identified, and the modeling results using 10 decomposition levels and two decomposition types were compared. The results affirmed that the wavelet-based modeling performance is sensitive to the choice of decomposition level, which is determined by the time series analyzed, but has no relation with the decomposition type used. The essence of the choice of decomposition level is to reveal the complex variability of hydrological time series under multi-temporal scales, and first knowing the true components of series could guide the choice of decomposition level. Through this study, the relationship among original series’ characteristics, the choice of decomposition level, and the accuracy of wavelet-based hydrological time series forecasting can be more clearly understood, and it can be an improvement for wavelet-based data-driven modeling. Full article
(This article belongs to the Special Issue Tackling Complex Water Problems in China under Changing Environment)
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5239 KiB  
Article
Regional Quasi-Three-Dimensional Unsaturated-Saturated Water Flow Model Based on a Vertical-Horizontal Splitting Concept
by Yan Zhu, Liangsheng Shi, Jingwei Wu, Ming Ye, Lihong Cui and Jinzhong Yang
Water 2016, 8(5), 195; https://doi.org/10.3390/w8050195 - 12 May 2016
Cited by 5 | Viewed by 6036
Abstract
Due to the high nonlinearity of the three-dimensional (3-D) unsaturated-saturated water flow equation, using a fully 3-D numerical model is computationally expensive for large scale applications. A new unsaturated-saturated water flow model is developed in this paper based on the vertical/horizontal splitting (VHS) [...] Read more.
Due to the high nonlinearity of the three-dimensional (3-D) unsaturated-saturated water flow equation, using a fully 3-D numerical model is computationally expensive for large scale applications. A new unsaturated-saturated water flow model is developed in this paper based on the vertical/horizontal splitting (VHS) concept to split the 3-D unsaturated-saturated Richards’ equation into a two-dimensional (2-D) horizontal equation and a one-dimensional (1-D) vertical equation. The horizontal plane of average head gradient in the triangular prism element is derived to split the 3-D equation into the 2-D equation. The lateral flow in the horizontal plane of average head gradient represented by the 2-D equation is then calculated by the water balance method. The 1-D vertical equation is discretized by the finite difference method. The two equations are solved simultaneously by coupling them into a unified nonlinear system with a single matrix. Three synthetic cases are used to evaluate the developed model code by comparing the modeling results with those of Hydrus1D, SWMS2D and FEFLOW. We further apply the model to regional-scale modeling to simulate groundwater table fluctuations for assessing the model applicability in complex conditions. The proposed modeling method is found to be accurate with respect to measurements. Full article
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1261 KiB  
Communication
The Status of Domestic Water Demand: Supply Deficit in the Kathmandu Valley, Nepal
by Parmeshwar Udmale, Hiroshi Ishidaira, Bhesh Raj Thapa and Narendra Man Shakya
Water 2016, 8(5), 196; https://doi.org/10.3390/w8050196 - 11 May 2016
Cited by 56 | Viewed by 18426
Abstract
United Nations Sustainable Development Goal 6 targets access to water and sanitation for all people in the next 15 years. However, for developing countries such as Nepal, it is more challenging to achieve this goal given its poor infrastructure and high population growth. [...] Read more.
United Nations Sustainable Development Goal 6 targets access to water and sanitation for all people in the next 15 years. However, for developing countries such as Nepal, it is more challenging to achieve this goal given its poor infrastructure and high population growth. To assess the water crisis in the most developed and populated area of Nepal, the Kathmandu Valley, we estimated available water resources and domestic water demand in the valley. We estimated a supply deficit of 102 million liters per day (MLD) in 2016, after completion of the first phase of the Melamchi Water Supply Project (MWSP). If the MWSP is completed within the specified timeframe, and sufficient treatment and distribution infrastructure is developed, then there would be no water deficit by 2023–2025. This indicates that the MWSP will make a significant contribution to the valley’s water security. However, emphasis must be given to utilizing all of the water available from the MWSP by developing sufficient water treatment and distribution infrastructure. Alternate mitigation options, such as planning land use for potential recharge, introducing micro- to macro-level rainwater harvesting structures, conjunctive use of surface and groundwater resources, and water demand-side management, would also be helpful. Full article
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2835 KiB  
Article
Treatment of Simulated Coalbed Methane Produced Water Using Direct Contact Membrane Distillation
by Dong-Wan Cho, Hocheol Song, Kwangsuk Yoon, Sewoon Kim, Jeongmin Han and Jinwoo Cho
Water 2016, 8(5), 194; https://doi.org/10.3390/w8050194 - 10 May 2016
Cited by 10 | Viewed by 7482
Abstract
Expolitation of coalbed methane (CBM) involves production of a massive amount saline water that needs to be properly managed for environmental protection. In this study, direct contact membrane distillation (DCMD) was utilized for treatment of CBM-produced water to remove saline components in the [...] Read more.
Expolitation of coalbed methane (CBM) involves production of a massive amount saline water that needs to be properly managed for environmental protection. In this study, direct contact membrane distillation (DCMD) was utilized for treatment of CBM-produced water to remove saline components in the water. Simulated CBM waters containing varying concentrations of NaCl (1, 20, and 500 mM) and NaHCO3 (1 and 25 mM) were used as feed solutions under two transmembrane temperatures (Δ40 and 60 °C). In short-term distillation (~360 min), DCMD systems showed good performance with nearly 100% removal of salts for all solutes concentrations at both temperatures. The permeate flux increased with the feed temperature, but at a given temperature, it remained fairly stable throughout the whole operation. A gradual decline in permeate flux was observed at Δ60 °C at high NaHCO3 concentration (25 mM). In long-term distillation (5400 min), the presence of 25 mM NaHCO3 further decreased the flux to 25%–35% of the initial value toward the end of the operation, likely due to membrane fouling by deposition of Ca-carbonate minerals on the pore openings. Furthermore, pore wetting by the scalants occurred at the end of the experiment, and it increased the distillate conducitivity to 110 µS·cm−1. The precipitates formed on the surface were dominantly CaCO3 crystals, identified as aragonite. Full article
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3653 KiB  
Article
The Water-Energy-Food Nexus and the Transboundary Context: Insights from Large Asian Rivers
by Marko Keskinen, Joseph H. A. Guillaume, Mirja Kattelus, Miina Porkka, Timo A. Räsänen and Olli Varis
Water 2016, 8(5), 193; https://doi.org/10.3390/w8050193 - 10 May 2016
Cited by 123 | Viewed by 17849
Abstract
The water-energy-food nexus is a topical subject for research and practice, reflecting the importance of these sectors for humankind and the complexity and magnitude of the challenges they are facing. While the nexus as a concept is not yet mature or fully tested [...] Read more.
The water-energy-food nexus is a topical subject for research and practice, reflecting the importance of these sectors for humankind and the complexity and magnitude of the challenges they are facing. While the nexus as a concept is not yet mature or fully tested in practice, it has already encouraged a range of approaches in a variety of contexts. This article provides a set of definitions recognizing three perspectives that see the nexus as an analytical tool, governance framework and as an emerging discourse. It discusses the implications that an international transboundary context brings to the nexus and vice versa. Based on a comparative analysis of three Asian regions—Central Asia, South Asia and the Mekong Region—and their related transboundary river basins, we propose that the transboundary context has three major implications: diversity of scales and perspectives, importance of state actors and importance of politics. Similarly, introducing the nexus as an approach in a transboundary context has a potential to provide new resources and approaches, alter existing actor dynamics and portray a richer picture of relationships. Overall, the significance of water-energy-food linkages and their direct impacts on water allocation mean that the nexus has the potential to complement existing approaches also in the transboundary river basins. Full article
(This article belongs to the Special Issue Water-Energy-Food Nexus in Large Asian River Basins)
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2197 KiB  
Article
Impacts of Climate and Land Use/Cover Change on Streamflow Using SWAT and a Separation Method for the Xiying River Basin in Northwestern China
by Jing Guo, Xiaoling Su, Vijay P. Singh and Jiming Jin
Water 2016, 8(5), 192; https://doi.org/10.3390/w8050192 - 7 May 2016
Cited by 45 | Viewed by 8667
Abstract
A better understanding of the effects of climate change and land use/cover change (LUCC) on streamflow promotes the long-term water planning and management in the arid regions of northwestern China. In this paper, the Soil and Water Assessment Tool (SWAT) and a separation [...] Read more.
A better understanding of the effects of climate change and land use/cover change (LUCC) on streamflow promotes the long-term water planning and management in the arid regions of northwestern China. In this paper, the Soil and Water Assessment Tool (SWAT) and a separation approach were used to evaluate and separate the effects of climate change and LUCC on streamflow in the Xiying River basin. The SWAT model was calibrated by the hydro-meteorological data from 1980–1989 to obtain the optimum parameters, which were validated by the subsequent application to the period between 1990–2008. Moreover, streamflow under several scenarios with different climate change and land use conditions in 1990–2008 and 2010–2069 were further investigated. Results indicate that, in the period of 1990–2008, the streamflow was dominated by climate change (i.e., changes in precipitation and temperature), which led to a 102.8% increase in the mean annual streamflow, whereas LUCC produced a decrease of 2.8%. Furthermore, in the future period of 2010–2039, the mean annual streamflow will decrease by 5.4% and 4.5% compared with the data of 1961–1990 under scenarios A2 and B2, respectively, while it will decrease by 21.2% and 16.9% in the period of 2040–2069, respectively. Full article
(This article belongs to the Special Issue Tackling Complex Water Problems in China under Changing Environment)
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460 KiB  
Article
Ecosystem Perceptions in Flood Prone Areas: A Typology and Its Relationship to Preferences for Governance
by Julia Baird, Angela Dzyundzyak, Ryan Plummer, Ryan Bullock, Diane Dupont, Marilyne Jollineau, Wendee Kubik, Gary Pickering and Liette Vasseur
Water 2016, 8(5), 191; https://doi.org/10.3390/w8050191 - 7 May 2016
Cited by 10 | Viewed by 6731
Abstract
A shift appears to be occurring in thinking about flooding, from a resistance-based approach to one of resilience. Accordingly, how stakeholders in flood-prone regions perceive the system and its governance are salient questions. This study queried stakeholders’ internal representations of ecosystems (resistance- or [...] Read more.
A shift appears to be occurring in thinking about flooding, from a resistance-based approach to one of resilience. Accordingly, how stakeholders in flood-prone regions perceive the system and its governance are salient questions. This study queried stakeholders’ internal representations of ecosystems (resistance- or resilience-based), preferences for governance actors and mechanisms for flooding, and the relationship between them in five different regions of the world. The influence of personal experience on these variables was also assessed. Most respondents aligned themselves with a resilience-based approach in relation to system connectedness and response to disturbance; however, respondents were almost evenly split between resistance- and resilience-based approaches when considering system management. Responses generally were considered to hold for other disturbances as well. There was no clear relationship between internal representations and preferences for governance actors or mechanisms. Respondents generally favoured actor combinations that included governments and mechanism combinations that included regulations and policies. Those who had personal experience with flooding tended to align themselves with a resilience-based internal representation of system management, but personal experience showed no clear relationship with governance preferences. The findings support an evolutionary perspective of flood management where emerging paradigms enhance preceding ones, and prompt a critical discussion about the universality of resilience as a framing construct. Full article
(This article belongs to the Special Issue Water Governance in Times of Change: Perceptions, Institutions, Praxis and Learning)
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5481 KiB  
Article
Historical Trends in Mean and Extreme Runoff and Streamflow Based on Observations and Climate Models
by Behzad Asadieh, Nir Y. Krakauer and Balázs M. Fekete
Water 2016, 8(5), 189; https://doi.org/10.3390/w8050189 - 7 May 2016
Cited by 28 | Viewed by 8585
Abstract
To understand changes in global mean and extreme streamflow volumes over recent decades, we statistically analyzed runoff and streamflow simulated by the WBM-plus hydrological model using either observational-based meteorological inputs from WATCH Forcing Data (WFD), or bias-corrected inputs from five global climate models [...] Read more.
To understand changes in global mean and extreme streamflow volumes over recent decades, we statistically analyzed runoff and streamflow simulated by the WBM-plus hydrological model using either observational-based meteorological inputs from WATCH Forcing Data (WFD), or bias-corrected inputs from five global climate models (GCMs) provided by the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). Results show that the bias-corrected GCM inputs yield very good agreement with the observation-based inputs in average magnitude of runoff and streamflow. On global average, the observation-based simulated mean runoff and streamflow both decreased about 1.3% from 1971 to 2001. However, GCM-based simulations yield increasing trends over that period, with an inter-model global average of 1% for mean runoff and 0.9% for mean streamflow. In the GCM-based simulations, relative changes in extreme runoff and extreme streamflow (annual maximum daily values and annual-maximum seven-day streamflow) are slightly greater than those of mean runoff and streamflow, in terms of global and continental averages. Observation-based simulations show increasing trend in mean runoff and streamflow for about one-half of the land areas and decreasing trend for the other half. However, mean and extreme runoff and streamflow based on the GCMs show increasing trend for approximately two-thirds of the global land area and decreasing trend for the other one-third. Further work is needed to understand why GCM simulations appear to indicate trends in streamflow that are more positive than those suggested by climate observations, even where, as in ISI-MIP, bias correction has been applied so that their streamflow climatology is realistic. Full article
(This article belongs to the Special Issue Forecast of Extreme Events in the Water Cycle—Data, Models and Uncertainties)
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3159 KiB  
Article
Riverbed Micromorphology of the Yangtze River Estuary, China
by Shuaihu Wu, Heqin Cheng, Y. Jun Xu, Jiufa Li, Shuwei Zheng and Wei Xu
Water 2016, 8(5), 190; https://doi.org/10.3390/w8050190 - 6 May 2016
Cited by 17 | Viewed by 7171
Abstract
Dunes are present in nearly all fluvial channels and are vital in understanding sediment transport, deposition, and flow conditions during floods of rivers and estuaries. This information is pertinent for helping developing management practices to reduce risks in river transportation and engineering. Although [...] Read more.
Dunes are present in nearly all fluvial channels and are vital in understanding sediment transport, deposition, and flow conditions during floods of rivers and estuaries. This information is pertinent for helping developing management practices to reduce risks in river transportation and engineering. Although a few recent studies have investigated the micromorphology of a portion of the Yangtze River estuary in China, our understanding of dune development in this large estuary is incomplete. It is also poorly understood how the development and characteristics of these dunes have been associated with human activities in the upper reach of the Yangtze River and two large-scale engineering projects in the estuarine zone. This study analyzed the feature in micromorphology of the entire Yangtze River estuary bed over the past three years and assessed the morphological response of the dunes to recent human activities. In 2012, 2014, and 2015, multi-beam bathymetric measurements were conducted on the channel surface of the Yangtze River estuary. The images were analyzed to characterize the subaqueous dunes and detect their changes over time. Bottom sediment samples were collected for grain size analysis to assess the physical properties of the dunes. We found that dunes in the Yangtze River estuary can be classified in four major classes: very large dunes, large dunes, medium dunes, and small dunes. Large dunes were predominant, amounting to 51.5%. There was a large area of dunes developed in the middle and upper reaches of the Yangtze River estuary and in the Hengsha Passage. A small area of dunes was observed for the first time in the turbidity maximum zone of the Yangtze River estuary. These dunes varied from 0.12 to 3.12 m in height with a wide range of wavelength from 2.83 to 127.89 m, yielding a range in height to wavelength of 0.003–0.136. Sharp leeside slope angles suggest that the steep slopes of asymmetrical dunes in the middle and upper reaches, and the turbidity maximum zone of the Yangtze River estuary face predominantly towards tides because of the ebb-dominated currents. Sharp windward slope angles in the lower reach of the North Passage show the influence of flood-dominated currents on dunes. It is likely that the scale of dunes will increase in the future in the South Channel because of a sharp decline of sediment discharge caused by recent human activities. Full article
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3594 KiB  
Article
Identification of Outlier Loci Responding to Anthropogenic and Natural Selection Pressure in Stream Insects Based on a Self-Organizing Map
by Bin Li, Kozo Watanabe, Dong-Hwan Kim, Sang-Bin Lee, Muyoung Heo, Heui-Soo Kim and Tae-Soo Chon
Water 2016, 8(5), 188; https://doi.org/10.3390/w8050188 - 6 May 2016
Cited by 4 | Viewed by 6752
Abstract
Water quality maintenance should be considered from an ecological perspective since water is a substrate ingredient in the biogeochemical cycle and is closely linked with ecosystem functioning and services. Addressing the status of live organisms in aquatic ecosystems is a critical issue for [...] Read more.
Water quality maintenance should be considered from an ecological perspective since water is a substrate ingredient in the biogeochemical cycle and is closely linked with ecosystem functioning and services. Addressing the status of live organisms in aquatic ecosystems is a critical issue for appropriate prediction and water quality management. Recently, genetic changes in biological organisms have garnered more attention due to their in-depth expression of environmental stress on aquatic ecosystems in an integrative manner. We demonstrate that genetic diversity would adaptively respond to environmental constraints in this study. We applied a self-organizing map (SOM) to characterize complex Amplified Fragment Length Polymorphisms (AFLP) of aquatic insects in six streams in Japan with natural and anthropogenic variability. After SOM training, the loci compositions of aquatic insects effectively responded to environmental selection pressure. To measure how important the role of loci compositions was in the population division, we altered the AFLP data by flipping the existence of given loci individual by individual. Subsequently we recognized the cluster change of the individuals with altered data using the trained SOM. Based on SOM recognition of these altered data, we determined the outlier loci (over 90th percentile) that showed drastic changes in their belonging clusters (D). Subsequently environmental responsiveness (Ek’) was also calculated to address relationships with outliers in different species. Outlier loci were sensitive to slightly polluted conditions including Chl-a, NH4-N, NOX-N, PO4-P, and SS, and the food material, epilithon. Natural environmental factors such as altitude and sediment additionally showed relationships with outliers in somewhat lower levels. Poly-loci like responsiveness was detected in adapting to environmental constraints. SOM training followed by recognition shed light on developing algorithms de novo to characterize loci information without a priori knowledge of population genetics. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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2189 KiB  
Article
Effects of Land Use Types on Community Structure Patterns of Benthic Macroinvertebrates in Streams of Urban Areas in the South of the Korea Peninsula
by Dong-Hwan Kim, Tae-Soo Chon, Gyu-Suk Kwak, Sang-Bin Lee and Young-Seuk Park
Water 2016, 8(5), 187; https://doi.org/10.3390/w8050187 - 6 May 2016
Cited by 18 | Viewed by 6832
Abstract
Benthic macroinvertebrates were collected from streams located in an urban area from regions featuring different environmental conditions. Physicochemical variables and land use types pertaining to sampling sites were analyzed concurrently. Multivariate analyses (cluster analysis and non-metric multidimensional scaling) and rank-abundance diagrams were used [...] Read more.
Benthic macroinvertebrates were collected from streams located in an urban area from regions featuring different environmental conditions. Physicochemical variables and land use types pertaining to sampling sites were analyzed concurrently. Multivariate analyses (cluster analysis and non-metric multidimensional scaling) and rank-abundance diagrams were used to characterize community patterns to assess ecological integrity in response to environmental conditions. Species composition patterns were mainly influenced by both the gradient of physicochemical variables (e.g., altitude, slope, conductivity) and the proportion of forest area. Community structure patterns were further correlated to the proportion of urbanization and to biological indices (e.g., diversity, number of species). Land use preferences of benthic species were identified based on the indicator values and weighted averaging regression models. Plecoptera species were representative of undisturbed streams in forest areas, whereas Tubificidae species and filtering collector caddis flies were indicator taxa in severely polluted and agricultural areas, respectively. The analyses of community structures and indicator species effectively characterized community properties and ecological integrity following natural and anthropogenic variability in urban stream ecosystems. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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