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Water, Volume 9, Issue 7 (July 2017)

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Cover Story (view full-size image) Constructed wetlands are frequently used for the treatment of agricultural runoff. This research [...] Read more.
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Open AccessArticle A Hydrological and Geomorphometric Approach to Understanding the Generation of Wadi Flash Floods
Water 2017, 9(7), 553; https://doi.org/10.3390/w9070553
Received: 14 June 2017 / Revised: 16 July 2017 / Accepted: 20 July 2017 / Published: 24 July 2017
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Abstract
Abstract: The generation and processes of wadi flash floods are very complex and are not well understood. In this paper, we investigate the relationship between variations in geomorphometric and rainfall characteristics and the responses of wadi flash floods. An integrated approach was developed
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Abstract: The generation and processes of wadi flash floods are very complex and are not well understood. In this paper, we investigate the relationship between variations in geomorphometric and rainfall characteristics and the responses of wadi flash floods. An integrated approach was developed based on geomorphometric analysis and hydrological modeling. The Wadi Qena, which is located in the Eastern Desert of Egypt, was selected to validate the developed approach and was divided into 14 sub-basins with areas ranging from 315 to 1488 km2. The distributed Hydrological River Basin Environment Assessment Model (Hydro-BEAM) was used to obtain a good representation of the spatial variability of the rainfall and geomorphology in the basin. Thirty-eight geomorphometric parameters representing the topographic, scale, shape and drainage characteristics of the basins were considered and extracted using geographic information system (GIS) techniques. A series of flash flood events from 1994, 2010, 2013, and 2014, in addition to synthetic virtual storms with different durations and intensities, were selected for the application of this study. The results exhibit strong correlations between scale and topographic parameters and the hydrological indices of the wadi flash floods, while the shape and drainage network metrics have smaller impacts. The total rainfall amount and duration significantly impact the relationship between the hydrologic response of the wadi and its geomorphometry. For most of the parameters, we found that the impact of the wadi geomorphometry on the hydrologic response increases with increasing rainfall intensity. Full article
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Open AccessArticle Linkage of Climatic Factors and Human Activities with Water Level Fluctuations in Qinghai Lake in the Northeastern Tibetan Plateau, China
Water 2017, 9(7), 552; https://doi.org/10.3390/w9070552
Received: 23 May 2017 / Revised: 7 July 2017 / Accepted: 13 July 2017 / Published: 24 July 2017
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Abstract
Changes in the water level of Qinghai Lake, the largest inland lake in China, directly affect the ecological security of Qinghai province and even the northwest of China. This study aimed to investigate the lake level and identify causes of changes in the
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Changes in the water level of Qinghai Lake, the largest inland lake in China, directly affect the ecological security of Qinghai province and even the northwest of China. This study aimed to investigate the lake level and identify causes of changes in the lake level of Qinghai Lake. The results showed that the lake level was 3196.55 m in 1959 and gradually declined to 3192.86 m in 2004, with an average decreasing rate of 8.2 cm·year−1 over 45 years. However, the lake level increased continuously by 1.04 m from 2005 to 2010. During the period 1961–2010, the annual average temperature showed an increasing trend in the Qinghai Lake basin, at a rate of 0.32 °C/decade, and the annual precipitation showed obvious fluctuations with an average precipitation of 381.70 mm/year. Annual evaporation showed a decreasing trend (−30.80 mm/decade). The change in lake level was positively correlated to precipitation, surface runoff water and groundwater inflow into the lake and negatively correlated to evaporation from the lake surface. The total water consumption by human activities merely accounted for a very small part of precipitation, surface runoff inflow and groundwater inflow (1.97%) and of lake evaporation (1.87%) in Qinghai Lake basin. The annual water consumption of artificial afforestation and grass plantation accounting for 5.07% of total precipitation, surface runoff inflow and groundwater inflow and 5.43% of the lake evaporation. Therefore, the water level depended more on climatic factors than on anthropogenic factors. Full article
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Open AccessArticle Evaluating the Effects of Low Impact Development Practices on Urban Flooding under Different Rainfall Intensities
Water 2017, 9(7), 548; https://doi.org/10.3390/w9070548
Received: 30 March 2017 / Revised: 26 June 2017 / Accepted: 12 July 2017 / Published: 24 July 2017
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Abstract
Low impact development (LID) is an important control measure against extreme rainfall events and is widely applied to relieve urban flood disasters. To investigate the effects of LID practices on flooding control under different rainfall scenarios, this paper constructs a rainfall–runoff model based
[...] Read more.
Low impact development (LID) is an important control measure against extreme rainfall events and is widely applied to relieve urban flood disasters. To investigate the effects of LID practices on flooding control under different rainfall scenarios, this paper constructs a rainfall–runoff model based on the storm water management model (SWMM) for a typical residential area in Guangzhou, China. The model is calibrated by using observed rainfall and runoff data. A total of 27 rainfall scenarios are constructed to simulate the change characteristics before and after the LID practices. Also, the projection pursuit method based on a particle swarm optimization (PSO) algorithm is used to assess the flooding characteristics. The results show that the constructed rainfall–runoff model can closely reflect the relationship between rainfall and runoff, with all Nash–Sutcliffe coefficients of efficiency (NSE) exceeding 0.7. It was found from the simulation and assessment of the constructed rainfall scenarios that the changes in rainfall characteristics have a considerable impact on the constructed drainage system and that LID practices can properly control the floods. However, with an increase in rainfall peak coefficient, intensity or duration, the control effects of LID tend to reduce. Particularly in the scenario of relatively high rainfall intensity, the impact of rainfall duration and the rainfall peak coefficient on the LID practices is minor. Full article
(This article belongs to the Special Issue Hillslope and Watershed Hydrology)
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Open AccessArticle Regional Groundwater Flow Assessment in a Prospective High-Level Radioactive Waste Repository of China
Water 2017, 9(7), 551; https://doi.org/10.3390/w9070551
Received: 13 June 2017 / Revised: 7 July 2017 / Accepted: 17 July 2017 / Published: 23 July 2017
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Abstract
The production of nuclear energy will result in high-level radioactive waste (HLRW), which brings potential environmental dangers. Selecting a proper disposal repository is a crucial step in the development of nuclear energy. This paper introduces firstly the hydrogeological conditions of the Beishan area
[...] Read more.
The production of nuclear energy will result in high-level radioactive waste (HLRW), which brings potential environmental dangers. Selecting a proper disposal repository is a crucial step in the development of nuclear energy. This paper introduces firstly the hydrogeological conditions of the Beishan area in China. Next, a regional groundwater model is constructed using a multiphase flow simulator to analyze the groundwater flow pattern in the Beishan area. Model calibration shows that the simulated and observed hydraulic heads match well, and the simulated regional groundwater flow pattern is similar to the surface flow pattern from the channel network, indicating that the groundwater flow is mainly dependent on the topography. In addition, the simulated groundwater storage over the period from 2003 to 2014 is similar to the trend derived from the Gravity Recovery and Climate Experiment satellite-derived results. Last, the established model is used to evaluate the influences of the extreme climate and regional faults on the groundwater flow pattern. It shows that they do not have a significant influence on the regional groundwater flow patterns. This study will provide a preliminary reference for the regional groundwater flow assessment in the site of the HLRW in China. Full article
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Open AccessArticle Source Water Protection Planning for Ontario First Nations Communities: Case Studies Identifying Challenges and Outcomes
Water 2017, 9(7), 550; https://doi.org/10.3390/w9070550
Received: 29 April 2017 / Revised: 14 July 2017 / Accepted: 18 July 2017 / Published: 22 July 2017
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Abstract
After the Walkerton tragedy in 2000, where drinking water contamination left seven people dead and many suffering from chronic illness, the Province of Ontario, Canada implemented policies to develop Source Water Protection (SWP) plans. Under the Clean Water Act (2006), thirty-six regional Conservation
[...] Read more.
After the Walkerton tragedy in 2000, where drinking water contamination left seven people dead and many suffering from chronic illness, the Province of Ontario, Canada implemented policies to develop Source Water Protection (SWP) plans. Under the Clean Water Act (2006), thirty-six regional Conservation Authorities were mandated to develop watershed-based SWP plans under 19 Source Protection Regions. Most First Nations in Ontario are outside of these Source Protection Regions and reserve lands are under Federal jurisdiction. This paper explores how First Nations in Ontario are attempting to address SWP to improve drinking water quality in their communities even though these communities are not part of the Ontario SWP framework. The case studies highlight the gap between the regulatory requirements of the Federal and Provincial governments and the challenges for First Nations in Ontario from lack of funding to implement solutions to address the threats identified in SWP planning. This analysis of different approaches taken by Ontario First Nations shows that the Ontario framework for SWP planning is not an option for the majority of First Nations communities, and does not adequately address threats originating on reserve lands. First Nations attempting to address on-reserve threats to drinking water are using a variety of resources and approaches to develop community SWP plans. However, a common theme of all the cases surveyed is a lack of funding to support implementing solutions for the threats identified by the SWP planning process. Federal government initiatives to address the chronic problem of boil water advisories within Indigenous communities do not recognize SWP planning as a cost-effective tool for improving drinking water quality. Full article
(This article belongs to the Special Issue Source Water Protection: State of the Art and Science)
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Open AccessArticle An Examination of Soil Moisture Estimation Using Ground Penetrating Radar in Desert Steppe
Water 2017, 9(7), 521; https://doi.org/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
[...] Read more.
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 Simulation of Typhoon-Induced Storm Tides and Wind Waves for the Northeastern Coast of Taiwan Using a Tide–Surge–Wave Coupled Model
Water 2017, 9(7), 549; https://doi.org/10.3390/w9070549
Received: 13 June 2017 / Revised: 17 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
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Abstract
The storm tide is a combination of the astronomical tide and storm surge, which is the actual sea water level leading to flooding in low-lying coastal areas. A full coupled modeling system (Semi-implicit Eulerian-Lagrangian Finite-Element model coupled with Wind Wave Model II, SELFE-WWM-II)
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The storm tide is a combination of the astronomical tide and storm surge, which is the actual sea water level leading to flooding in low-lying coastal areas. A full coupled modeling system (Semi-implicit Eulerian-Lagrangian Finite-Element model coupled with Wind Wave Model II, SELFE-WWM-II) for simulating the interaction of tide, surge and waves based on an unstructured grid is applied to simulate the storm tide and wind waves for the northeastern coast of Taiwan. The coupled model was driven by the astronomical tide and consisted of main eight tidal constituents and the meteorological forcings (air pressure and wind stress) of typhoons. SELFE computes the depth-averaged current and water surface elevation passed to WWM-II, while WWM-II passes the radiation stress to SELFE by solving the wave action equation. Hindcasts of wind waves and storm tides for five typhoon events were developed to validate the coupled model. The detailed comparisons generally show good agreement between the simulations and measurements. The contributions of surge induced by wave and meteorological forcings to the storm tide were investigated for Typhoon Soudelor (2015) at three tide gauge stations. The results reveal that the surge contributed by wave radiation stress was 0.55 m at Suao Port due to the giant offshore wind wave (exceeding 16.0 m) caused by Typhoon Soudelor (2015) and the steep sea-bottom slope. The air pressure resulted in a 0.6 m surge at Hualien Port because of an inverted barometer effect. The wind stress effect was only slightly significant at Keelung Port, contributing 0.22 m to the storm tide. We conclude that wind waves should not be neglected when modeling typhoon-induced storm tides, especially in regions with steep sea-bottom slopes. In addition, accurate tidal and meteorological forces are also required for storm tide modeling. Full article
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Open AccessArticle Inactivation Effect of Antibiotic-Resistant Gene Using Chlorine Disinfection
Water 2017, 9(7), 547; https://doi.org/10.3390/w9070547
Received: 19 June 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 21 July 2017
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Abstract
The aim of this study was to elucidate the inactivation effects on the antibiotic-resistance gene (vanA) of vancomycin-resistant enterococci (VRE) using chlorination, a disinfection method widely used in various water treatment facilities. Suspensions of VRE were prepared by adding VRE to
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The aim of this study was to elucidate the inactivation effects on the antibiotic-resistance gene (vanA) of vancomycin-resistant enterococci (VRE) using chlorination, a disinfection method widely used in various water treatment facilities. Suspensions of VRE were prepared by adding VRE to phosphate-buffered saline, or the sterilized secondary effluent of a wastewater treatment plant. The inactivation experiments were carried out at several chlorine concentrations and stirring time. Enterococci concentration and presence of vanA were determined. The enterococci concentration decreased as chlorine concentrations and stirring times increased, with more than 7.0 log reduction occurring under the following conditions: 40 min stirring at 0.5 mg Cl2/L, 20 min stirring at 1.0 mg Cl2/L, and 3 min stirring at 3.0 mg Cl2/L. In the inactivation experiment using VRE suspended in secondary effluent, the culturable enterococci required much higher chlorine concentration and longer treatment time for complete disinfection than the cases of suspension of VRE. However, vanA was detected in all chlorinated suspensions of VRE, even in samples where no enterococcal colonies were present on the medium agar plate. The chlorine disinfection was not able to destroy antibiotic-resistance genes, though it can inactivate and decrease bacterial counts of antibiotic-resistant bacteria (ARB). Therefore, it was suggested that remaining ARB and/or antibiotic-resistance gene in inactivated bacterial cells after chlorine disinfection tank could be discharged into water environments. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Open AccessArticle Short-Term Impacts of Remeandering Restoration Efforts on Fish Community Structure in a Fourth-Order Stream
Water 2017, 9(7), 546; https://doi.org/10.3390/w9070546
Received: 1 June 2017 / Revised: 4 July 2017 / Accepted: 17 July 2017 / Published: 20 July 2017
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Abstract
Channel reconfiguration is a common but debated method used to restore streams, often causing disturbance and producing subsequent negative impacts on biota. Here, we report results from short-term assessment (i.e., one and three years’ post-restoration) of habitat variables (e.g., reach depth, substrate, and
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Channel reconfiguration is a common but debated method used to restore streams, often causing disturbance and producing subsequent negative impacts on biota. Here, we report results from short-term assessment (i.e., one and three years’ post-restoration) of habitat variables (e.g., reach depth, substrate, and canopy cover) and fish community composition and structure (using electrofishing surveys; e.g., proportion of juveniles and tolerant fishes) from a 675 m section of Eagle Creek (Portage County, OH, USA) restored using channel remeandering in August 2013. Mesohabitat analysis was not conducted as part of this study. Sites upstream and downstream of restoration efforts were also monitored. Surveys were completed in 10 separate 50 m stretches: one upstream control site, three new channel sites, two old channel sites, and three downstream sites. Following restoration, fish communities in downstream sites became more similar to new channel sites and diverged from the upstream control site over time, as reflected in increased proportions of juvenile and tolerant fishes. Shifts in fish communities were not explained by habitat variables. Diversity was significantly lower in new channel sites post-restoration than in the upstream control, while downstream sites remained similarly high in diversity compared to the upstream control site over time. Overall, in the short-term, new channel colonizing communities were unable to recover to reflect upstream community composition and structure, and fish communities downstream of restoration were negatively impacted. Full article
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Open AccessArticle Long Term Trends and Dynamics of Dissolved Organic Carbon (DOC) in a Subtropical Reservoir Basin
Water 2017, 9(7), 545; https://doi.org/10.3390/w9070545
Received: 24 April 2017 / Revised: 30 June 2017 / Accepted: 11 July 2017 / Published: 20 July 2017
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Abstract
This study evaluates the long term trends and seasonal patterns of dissolved organic carbon (DOC) concentration in the Fei-Tsui Reservoir basin in Northern Taiwan during the period of 2000 to 2015. The non-parametric seasonal Mann-Kendall test was conducted to identify the trends of
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This study evaluates the long term trends and seasonal patterns of dissolved organic carbon (DOC) concentration in the Fei-Tsui Reservoir basin in Northern Taiwan during the period of 2000 to 2015. The non-parametric seasonal Mann-Kendall test was conducted to identify the trends of DOC and its potential drivers (e.g., temperature, runoff, atmospheric acid deposition and stream water chemistry). The monthly tributaries and water surface DOC concentrations in Fei-Tsui Reservoir had showed strong temporal and seasonal variability. The sulfate (SO4) concentration had exhibited statistically significant decreasing trend over a period of 16 years. The decreasing trends of anions (SO4 and NO3) and base cations (Ca and Mg) as well as increasing trends of pH and acidification index (ACI) in Fei-Tsui Reservoir and streams indicated recovery from acidification. However, there was no significant annual trend in DOC concentration of Fei-Tsui Reservoir and streams. Significant positive correlation was obtained between DOC and trophic state index of Fei-Tsui Reservoir. The results suggested that DOC concentration at the water surface of Fei-Tsui Reservoir was mainly driven by the re-oligotrophication and temperature effects rather than a decrease in atmospheric sulfur deposition. Stream DOC concentration was largely determined by the temporal variability in temperature and rainfall. We concluded that climatic and hydrological factors are the dominant drivers for stream DOC dynamics in the study. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle Potential Drivers of the Level and Distribution of Nitrogen in the Hyporheic Zone of Lake Taihu, China
Water 2017, 9(7), 544; https://doi.org/10.3390/w9070544
Received: 5 May 2017 / Revised: 30 June 2017 / Accepted: 17 July 2017 / Published: 20 July 2017
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Abstract
The hyporheic zone is the connection between surface water and groundwater that often plays an important function in nutrient transport and transformation, and acts as an active source of or sink for nutrients to the surface water, depending on its potential water flow
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The hyporheic zone is the connection between surface water and groundwater that often plays an important function in nutrient transport and transformation, and acts as an active source of or sink for nutrients to the surface water, depending on its potential water flow patterns. Bottom surface water and sediments in the shallow hyporheic zone (approximately 100 cm depth) were sampled at 12 sites near the shoreline and two sites at the center of Lake Taihu (China) during spring and winter of 2016. Concentrations of total nitrogen, ammonium, nitrate, and nitrite in the bottom surface water and porewater (obtained from sediments using a frozen centrifugation method) were analyzed in a laboratory to establish the nitrogen distribution and potential drivers. The results show that, in general, the quality of bottom water and porewater near the shoreline was poor compared to that at the center, and it gradually improved from the northwestern to the southeastern zones of Lake Taihu. No significant relationship in nitrogen concentration was found between the bottom water and porewater in surface sediments. Nitrogen concentrations in porewater differed between sampling sites and sediment depths in Lake Taihu. Vertical profiles of nitrogen in porewater and differences in nitrogen between the winter and spring seasons indicated that potential upwelling water flow occurred in the hyporheic zone in the south, west, north, and center zones of Lake Taihu, but potentially weak water flow in variable directions likely occurred in the east zone. A strong reducing environment dominated the deep parts of the hyporheic zone (i.e., below 40 cm depth), while a weak oxidizing environment dominated the shallow parts. Furthermore, the decreasing total nitrogen and ammonium nitrogen from the deep to shallow depths in the hyporheic zones in the south, west, north, and center zones indicated that potential anammox and/or denitrification processes occurred. In the east zone, potential weak nitrification processes occurred in the hyporheic zone, and plant fixation and sedimentation of nitrogen also contributed to the surface sediments. In conclusion, the hyporheic zone near the shoreline in the south, west, and north sites of Lake Taihu acts as an active source of nitrogen for the lake water due to potential upwelling water flows, whereas the east site acts as an active source or sink due to seasonally variable directions in water flow. Water flow and biogeochemistry in the hyporheic zone jointly influence nutrient distribution in the hyporheic zone and even switch or alternate the source/sink function of sediment in surface water. Full article
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Open AccessArticle Influencing Factors and Simplified Model of Film Hole Irrigation
Water 2017, 9(7), 543; https://doi.org/10.3390/w9070543
Received: 24 May 2017 / Revised: 28 June 2017 / Accepted: 17 July 2017 / Published: 20 July 2017
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Abstract
Film hole irrigation is an advanced low-cost and high-efficiency irrigation method, which can improve water conservation and water use efficiency. Given its various advantages and potential applications, we conducted a laboratory study to investigate the effects of soil texture, bulk density, initial soil
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Film hole irrigation is an advanced low-cost and high-efficiency irrigation method, which can improve water conservation and water use efficiency. Given its various advantages and potential applications, we conducted a laboratory study to investigate the effects of soil texture, bulk density, initial soil moisture, irrigation depth, opening ratio (ρ), film hole diameter (D), and spacing on cumulative infiltration using SWMS-2D. We then proposed a simplified model based on the Kostiakov model for infiltration estimation. Error analyses indicated SWMS-2D to be suitable for infiltration simulation of film hole irrigation. Additional SWMS-2D-based investigations indicated that, for a certain soil, initial soil moisture and irrigation depth had the weakest effects on cumulative infiltration, whereas ρ and D had the strongest effects on cumulative infiltration. A simplified model with ρ and D was further established, and its use was then expanded to different soils. Verification based on seven soil types indicated that the established simplified double-factor model effectively estimates cumulative infiltration for film hole irrigation, with a small mean average error of 0.141–2.299 mm, a root mean square error of 0.177–2.722 mm, a percent bias of −2.131–1.479%, and a large Nash–Sutcliffe coefficient that is close to 1.0. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessFeature PaperArticle New Potentiometric Wireless Chloride Sensors Provide High Resolution Information on Chemical Transport Processes in Streams
Water 2017, 9(7), 542; https://doi.org/10.3390/w9070542
Received: 26 May 2017 / Revised: 11 July 2017 / Accepted: 14 July 2017 / Published: 19 July 2017
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Abstract
Quantifying the travel times, pathways, and dispersion of solutes moving through stream environments is critical for understanding the biogeochemical cycling processes that control ecosystem functioning. Validation of stream solute transport and exchange process models requires data obtained from in-stream measurement of chemical concentration
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Quantifying the travel times, pathways, and dispersion of solutes moving through stream environments is critical for understanding the biogeochemical cycling processes that control ecosystem functioning. Validation of stream solute transport and exchange process models requires data obtained from in-stream measurement of chemical concentration changes through time. This can be expensive and time consuming, leading to a need for cheap distributed sensor arrays that respond instantly and record chemical transport at points of interest on timescales of seconds. To meet this need we apply new, low-cost (in the order of a euro per sensor) potentiometric chloride sensors used in a distributed array to obtain data with high spatial and temporal resolution. The application here is to monitoring in-stream hydrodynamic transport and dispersive mixing of an injected chemical, in this case NaCl. We present data obtained from the distributed sensor array under baseflow conditions for stream reaches in Luxembourg and Western Australia. The reaches were selected to provide a range of increasingly complex in-channel flow patterns. Mid-channel sensor results are comparable to data obtained from more expensive electrical conductivity meters, but simultaneous acquisition of tracer data at several positions across the channel allows far greater spatial resolution of hydrodynamic mixing processes and identification of chemical ‘dead zones’ in the study reaches. Full article
(This article belongs to the Special Issue New Developments in Methods for Hydrological Process Understanding)
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Open AccessArticle A Hybrid Model for Forecasting Groundwater Levels Based on Fuzzy C-Mean Clustering and Singular Spectrum Analysis
Water 2017, 9(7), 541; https://doi.org/10.3390/w9070541
Received: 27 April 2017 / Revised: 11 July 2017 / Accepted: 15 July 2017 / Published: 19 July 2017
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Abstract
Having the ability to forecast groundwater levels is very significant because of their vital role in basic functions related to efficiency and the sustainability of water supplies. The uncertainty which dominates our understanding of the functioning of water supply systems is of great
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Having the ability to forecast groundwater levels is very significant because of their vital role in basic functions related to efficiency and the sustainability of water supplies. The uncertainty which dominates our understanding of the functioning of water supply systems is of great significance and arises as a consequence of the time-unbalanced water consumption rate and the deterioration of the recharge conditions of captured aquifers. The aim of this paper is to present a hybrid model based on fuzzy C-mean clustering and singular spectrum analysis to forecast the weekly values of the groundwater level of a groundwater source. This hybrid model demonstrates how the fuzzy C-mean can be used to transform the sequence of the observed data into a sequence of fuzzy states, serving as a basis for the forecasting of future states by singular spectrum analysis. In this way, the forecasting efficiency is improved, because we predict the interval rather than the crisp value where the level will be. It gives much more flexibility to the engineers when managing and planning sustainable water supplies. A model is tested by using the observed weekly time series of the groundwater source, located near the town of Čačak in south-western Serbia. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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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; https://doi.org/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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