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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
Cited by 4 | Viewed by 2613 | PDF Full-text (12000 KB) | HTML Full-text | XML Full-text
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 [...] Read more.
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
Cited by 2 | Viewed by 1569 | PDF Full-text (2702 KB) | HTML Full-text | XML Full-text
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 [...] Read more.
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
Cited by 14 | Viewed by 1860 | PDF Full-text (9534 KB) | HTML Full-text | XML Full-text
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) Printed Edition available
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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
Cited by 4 | Viewed by 1943 | PDF Full-text (2806 KB) | HTML Full-text | XML Full-text | Supplementary Files
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
Cited by 6 | Viewed by 1688 | PDF Full-text (6267 KB) | HTML Full-text | XML Full-text
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) [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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 [...] Read more.
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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Open AccessArticle
Carbon Dioxide Emissions from the Littoral Zone of a Chinese Reservoir
Water 2017, 9(7), 539; https://doi.org/10.3390/w9070539
Received: 3 May 2017 / Revised: 10 July 2017 / Accepted: 14 July 2017 / Published: 19 July 2017
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Abstract
The continuous increase in the number of reservoirs globally has raised important questions about the environmental impact of their greenhouse gases emissions. In particular, the littoral zone may be a hotspot for production of greenhouse gases. We investigated the spatiotemporal variation of CO [...] Read more.
The continuous increase in the number of reservoirs globally has raised important questions about the environmental impact of their greenhouse gases emissions. In particular, the littoral zone may be a hotspot for production of greenhouse gases. We investigated the spatiotemporal variation of CO2 flux at the littoral zone of a Chinese reservoir along a wet-to-dry transect from permanently flooded land, seasonally flooded land to non-flooded dry land, using the static dark chamber technique. The mean total CO2 emission was 346 mg m−2 h−1 and the rate varied significantly by water levels, months and time of day. The spatiotemporal variation of flux was highly correlated with biomass, temperature and water level. Flooding could play a positive role in carbon balance if water recession occurs at the time when carbon gains associated with plant growth overcomes the carbon loss of ecosystem. The overall carbon balance was analysed using cumulative greenhouse gases fluxes and biomass, bringing the data of the present study alongside previously published, simultaneously measured CH4 and N2O fluxes. For the growing season, 12.8 g C m−2 was absorbed by the littoral zone. Taking CH4 and N2O into the calculation showed that permanently flooded sites were a source of greenhouse gases, rather than a sink. Our study emphasises how water level fluctuation influenced CO2, CH4 and N2O in different ways, which greatly affected the spatiotemporal variation and emission rate of greenhouse gases from the littoral zone. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle
Ontario’s Clean Water Act and Capacity Building: Implications for Serviced Rural Municipalities
Water 2017, 9(7), 538; https://doi.org/10.3390/w9070538
Received: 25 April 2017 / Revised: 7 July 2017 / Accepted: 10 July 2017 / Published: 18 July 2017
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Abstract
This research explores Ontario’s Clean Water Act (S.O. 2006, c. 22) and its contribution to capacity building for rural municipalities impacted by source protection plans created under the Act. Source water protection (SWP) under the Clean Water Act (S.O. 2006, c. 22) [...] Read more.
This research explores Ontario’s Clean Water Act (S.O. 2006, c. 22) and its contribution to capacity building for rural municipalities impacted by source protection plans created under the Act. Source water protection (SWP) under the Clean Water Act (S.O. 2006, c. 22) is explored drawing from a capacity framework. A nested case study approach has been employed to allow for in depth exploration of the experience within the Cataraqui Source Protection Area and the North Bay-Mattawa Source Protection Area, where key informant interviews were conducted. Findings are outlined looking at four elements of capacity for SWP: institutional, financial, social, and technical/human. It was found that the process was successful for building capacity in the serviced rural municipalities involved, but did not provide any meaningful protection for areas reliant on private drinking water systems such as wells. Several improvements to the legislated process were suggested including greater flexibility for local circumstance and better methods for engagement of First Nations and the general public. It is unknown if this capacity will be sustained as the program continues and provincial funding is reduced. Reduced funding will particularly impact rural communities that lack the internal human and financial capacity to implement SWP policies without the assistance of provincial funding and conservation authority staff (who also rely on provincial/municipal funding sources). Ultimately, it was found that SWP in rural areas requires enforceable mandatory legislation; sustainable provincial funding and municipal fiscal frameworks to support ongoing SWP planning and implementation; technical aid at the regional level; and support and commitment to SWP at the local level (e.g., municipalities, local health units, landowners, residents and watershed users). Full article
(This article belongs to the Special Issue Source Water Protection: State of the Art and Science)
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Open AccessArticle
Phosphorus Dynamics along River Continuum during Typhoon Storm Events
Water 2017, 9(7), 537; https://doi.org/10.3390/w9070537
Received: 11 February 2017 / Revised: 10 July 2017 / Accepted: 14 July 2017 / Published: 18 July 2017
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Abstract
Information on riverine phosphorus (P) dynamics during typhoon storm events remains scarce in subtropical regions. Thus, this study investigates the spatial and temporal dynamics of riverine phosphorus in a headwater catchment during three typhoon events. Continuous sampling (3 h intervals) of stormwater samples [...] Read more.
Information on riverine phosphorus (P) dynamics during typhoon storm events remains scarce in subtropical regions. Thus, this study investigates the spatial and temporal dynamics of riverine phosphorus in a headwater catchment during three typhoon events. Continuous sampling (3 h intervals) of stormwater samples and discharge data were conducted at five locations, which represent the upstream, transitional zone, and downstream areas of the main inflow river. The results revealed that the average event mean concentrations (EMCs) for total dissolved phosphorus (TDP) and particulate phosphorus (PP) in the upstream catchment of Fei-Tsui reservoir were 15.66 μg/L and 11.94 μg/L, respectively. There was at least a 1.3-fold increase in flow-weighted concentrations of TDP and PP from the upper to lower reaches of the main stream. PP and TDP were transported either in clockwise or anticlockwise directions, depending on storm intensity and source. The transport of TDP was primarily regulated by the subsurface flow during the storm event. Soluble reactive phosphorus (SRP) contributes more than 50% of the TDP load in moderate storms, while extreme storms supply a greater dissolved organic phosphorus (DOP) load into the stream. TDP accounted for approximately 50% of TP load during typhoon storms. Mobilization of all P forms was observed from upstream to downstream of the river, except for DOP. A decrease of DOP load on passing downstream may reflect the change in phosphorus form along the river continuum. Peak discharge and antecedent dry days are correlated positively with P fluxes, indicating that river bank erosion and re-suspension of within-channel sediment are the dominant pathways of P during typhoon storm periods. Full article
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Open AccessArticle
HYDRUS Simulation of Sustainable Brackish Water Irrigation in a Winter Wheat-Summer Maize Rotation System in the North China Plain
Water 2017, 9(7), 536; https://doi.org/10.3390/w9070536
Received: 5 May 2017 / Revised: 5 July 2017 / Accepted: 11 July 2017 / Published: 18 July 2017
Cited by 9 | Viewed by 1823 | PDF Full-text (4431 KB) | HTML Full-text | XML Full-text
Abstract
Freshwater resources in the North China Plain (NCP) are near depletion due to the unceasing overexploitation of deep groundwater, by far the most significant source of freshwater in the region. To deal with the deepening freshwater crisis, brackish water (rich but largely unused [...] Read more.
Freshwater resources in the North China Plain (NCP) are near depletion due to the unceasing overexploitation of deep groundwater, by far the most significant source of freshwater in the region. To deal with the deepening freshwater crisis, brackish water (rich but largely unused water in agriculture) is increasingly being used in irrigation in the region. However, inappropriate irrigation with brackish water could lead to soil salinization and cropland degradation. To evaluate such negative impacts, the HYDRUS-1D model was used to simulate soil salt transport and accumulation under 15 years of irrigation with brackish water. The irrigation scenarios included brackish water irrigation during the wintering and jointing stages of winter wheat and then freshwater irrigation just before the sowing of summer maize. Freshwater irrigation was done to leach out soil salts, which is particularly vital in dry years. For the littoral region of the plain, HYDRUS-ID was used to simulate the irrigated cropping system stated above for a total period of 15 years. The results showed that it was feasible to use brackish water twice in one year, provided freshwater irrigation was performed before sowing summer maize. Freshwater irrigation, in conjunction with precipitation, leached out soil salts from the 100 cm root-zone depth. The maximum salt accumulation was in the 160–220 cm soil layer, which ensured that root-zone soil was free of restrictive salinity for crop growth. Precipitation was a critical determinant of the rate and depth leaching of soil salt. Heavy rainfall (>100 mm) caused significant leaching of soluble salts in the 0–200 cm soil profile. Salt concentration under brackish water irrigation had no significant effect on the variations in the trend of soil salt transport in the soil profile. The variations of soil salinity were mainly affected by hydrological year type, for which the buried depth of soil salt was higher in wet years than in dry years. The study suggested that 15 years of irrigation with brackish water is a reliable and feasible mode of crop production in coastal regions with a thick soil column above the water table. The scheme proposed in this study allowed the use of brackish water in irrigation without undue salinization of the crop soil layer, an intuitive way of resolving the deepening water crisis in the NCP study area and beyond. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessArticle
Using Ostrom’s DPs as Fuzzy Sets to Analyse How Water Policies Challenge Community-Based Water Governance in Colombia
Water 2017, 9(7), 535; https://doi.org/10.3390/w9070535
Received: 16 May 2017 / Revised: 2 July 2017 / Accepted: 13 July 2017 / Published: 18 July 2017
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Abstract
Ostrom’s design principles have been broadly used to analyse the governance of common pool resources. However, they are normally assessed as present or absent. We challenge this assumption by considering them as fuzzy sets where membership scores range from 0 to 1, because, [...] Read more.
Ostrom’s design principles have been broadly used to analyse the governance of common pool resources. However, they are normally assessed as present or absent. We challenge this assumption by considering them as fuzzy sets where membership scores range from 0 to 1, because, in real situations, the design principles can be present at a certain level. We define categories to assess the level of membership and apply it to a single case study analysing how changes in water policy can affect the community-based management of the Water User Association of Mondomo (Colombia). In rural areas of Colombia, most water and sanitation services are provided by water user associations, wherein civil society has developed governance systems based on active citizen involvement and community-based management. Some of these associations have been operating for decades and are essential pillars of the local social fabric. However, recent changes in the country’s policy and legal framework threaten these long-lasting governance systems. The results show that most of the design principles would suffer important changes that undermine the governance system. Essential principles for sustainable community-based governance, such as the congruence of the rules with local conditions, the local monitoring and sanctioning capacities, the internal conflict-resolution mechanisms and the recognition of the rights to organize, are dramatically reduced after the policy implementation. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle
The Limits of Water Pricing in a Developing Country Metropolis: Empirical Lessons from an Industrial City of Pakistan
Water 2017, 9(7), 533; https://doi.org/10.3390/w9070533
Received: 10 May 2017 / Revised: 9 July 2017 / Accepted: 14 July 2017 / Published: 18 July 2017
Cited by 3 | Viewed by 1873 | PDF Full-text (1663 KB) | HTML Full-text | XML Full-text
Abstract
This paper seeks to question the effectiveness of water pricing as a means of consumer behavioural change in urban centres of the Global South by analysing the domestic usage for water in a major industrial city of Pakistan. Using survey data of 1100 [...] Read more.
This paper seeks to question the effectiveness of water pricing as a means of consumer behavioural change in urban centres of the Global South by analysing the domestic usage for water in a major industrial city of Pakistan. Using survey data of 1100 households from Faisalabad city, we estimate the price and income elasticities of water demand. Instrumental variable methods are applied to overcome the endogeneity issues of water pricing. The findings reflect that price and income elasticities vary across different groups. Price elasticities range from −0.43 to −0.71, and income elasticities vary between 0.01 and 0.12. These findings suggest that pricing policies may have limited scope to drive households’ water consumption patterns. However, these empirics may suggest that policy makers should design an appropriate tariff structure to increase revenues that can be invested to further improve the existing water infrastructure. The study findings also suggest that non-pricing instruments, such as water saving campaigns, may be helpful in driving an efficient use of water in rapidly growing cities in the developing world. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle
Membrane Bioreactor-Based Wastewater Treatment Plant in Saudi Arabia: Reduction of Viral Diversity, Load, and Infectious Capacity
Water 2017, 9(7), 534; https://doi.org/10.3390/w9070534
Received: 5 June 2017 / Revised: 2 July 2017 / Accepted: 8 July 2017 / Published: 17 July 2017
Cited by 7 | Viewed by 2765 | PDF Full-text (4475 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A membrane bioreactor (MBR)-based wastewater treatment plant in Saudi Arabia was assessed over a nine-month period for virus removal efficiency. Viral diversity was detected using omics-based approaches. Log reduction values (LRV) of Adenoviruses (AdV) and Enteroviruses (EV) were enumerated using digital polymerase chain [...] Read more.
A membrane bioreactor (MBR)-based wastewater treatment plant in Saudi Arabia was assessed over a nine-month period for virus removal efficiency. Viral diversity was detected using omics-based approaches. Log reduction values (LRV) of Adenoviruses (AdV) and Enteroviruses (EV) were enumerated using digital polymerase chain reaction (dPCR) and assessed for infectivity using fluorescence-based infection assays. MBR treatment was successful in reducing viral diversity. Plant viruses remained abundant in the treated effluent. Human enteric viruses were present in lower abundance than plant viruses, and were reduced by MBR at varying LRV. AdV copy numbers were reduced by 3.7-log. Infectious AdV was not detected in the effluent. EV copy numbers were reduced by 1.7-log post MBR and infectious EV decreased by an average of 2.0-log. Infectious EV was detected in the chlorinated effluent, occasionally in concentrations that approximate to its 50% infectious dose. Overall, results indicated that a MBR-based wastewater treatment plant (WWTP) effectively reduces viral diversity, viral load, and infectious capacity by up to 4-logs. These findings suggest potential concerns associated with plant and human enteric viruses for reuse events in this country. Local guidelines for assessment of treated water quality should take into consideration both infectious viral concentration and LRV. Full article
(This article belongs to the Special Issue Sustainable Water Supply through Desalination and Wastewater Reuse)
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Open AccessArticle
Total Discharge Estimation in the Korean Peninsula Using Multi-Satellite Products
Water 2017, 9(7), 532; https://doi.org/10.3390/w9070532
Received: 26 May 2017 / Revised: 12 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
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Abstract
Estimation of total discharge is necessary to understand the hydrological cycle and to manage water resources efficiently. However, the task is problematic in an area where ground observations are limited. The North Korea region is one example. Here, the total discharge was estimated [...] Read more.
Estimation of total discharge is necessary to understand the hydrological cycle and to manage water resources efficiently. However, the task is problematic in an area where ground observations are limited. The North Korea region is one example. Here, the total discharge was estimated based on the water balance using multiple satellite products. They are the terrestrial water storage changes (TWSC) derived from the Gravity Recovery and Climate Experiment (GRACE), precipitation from the Tropical Rainfall Measuring Mission (TRMM), and evapotranspiration from the Moderate Resolution Imaging Spectroradiometer (MODIS). The satellite-based discharge was compared with land surface model products of the Global Land Data Assimilation System (GLDAS), and a positive relationship between the results was obtained (r = 0.70–0.86; bias = −9.08–16.99 mm/month; RMSE = 36.90–62.56 mm/month; NSE = 0.01–0.62). Among the four land surface models of GLDAS (CLM, Mosaic, Noah, and VIC), CLM corresponded best with the satellite-based discharge, satellite-based discharge has a tendency to slightly overestimate compared to model-based discharge (CLM, Mosaic, Noah, and VIC) in the dry season. Also, the total discharge data based on the Precipitation-Runoff Modeling System (PRMS) and the in situ discharge for major five river basins in South Korea show comparable seasonality and high correlation with the satellite-based discharge. In spite of the relatively low spatial resolution of GRACE, and loss of information incurred during the process of integrating three different satellite products, the proposed methodology can be a practical tool to estimate the total discharge with reasonable accuracy, especially in a region with scarce hydrologic data. Full article
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Open AccessArticle
Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils
Water 2017, 9(7), 531; https://doi.org/10.3390/w9070531
Received: 2 June 2017 / Revised: 11 July 2017 / Accepted: 12 July 2017 / Published: 17 July 2017
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Abstract
In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P) into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were [...] Read more.
In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P) into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP), soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss. Full article
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Open AccessEditorial
Recent Advances in Soil Moisture Estimation from Remote Sensing
Water 2017, 9(7), 530; https://doi.org/10.3390/w9070530
Received: 9 June 2017 / Revised: 5 July 2017 / Accepted: 13 July 2017 / Published: 16 July 2017
Cited by 10 | Viewed by 2259 | PDF Full-text (184 KB) | HTML Full-text | XML Full-text
Abstract
Monitoring soil moisture dynamics from local to global scales is essential for a wide range of applications. The field of remote sensing of soil moisture has expanded greatly and the first dedicated soil moisture satellite missions (SMOS, SMAP) were launched, and new missions, [...] Read more.
Monitoring soil moisture dynamics from local to global scales is essential for a wide range of applications. The field of remote sensing of soil moisture has expanded greatly and the first dedicated soil moisture satellite missions (SMOS, SMAP) were launched, and new missions, such as SENTINEL-1 provide long-term perspectives for land surface monitoring. This special issue aims to summarize the recent advances in soil moisture estimation from remote sensing, including recent advances in retrieval algorithms, validation, and applications of satellite-based soil moisture products. Contributions in this special issue exploit the estimation of soil moisture from both microwave remote sensing data and thermal infrared information. The validation of satellite soil moisture products can be very challenging, due to the different spatial scales of in situ measurements and satellite data. Some papers present validation studies to quantify soil moisture uncertainties. On the other hand, soil moisture downscaling schemes and new methods for soil moisture retrieval from GPS are also addressed by some contributions. Soil moisture data are used in fields like agriculture, hydrology, and climate sciences. Several studies explore the use of soil moisture data for hydrological application such as runoff prediction. Full article
(This article belongs to the Special Issue Remote Sensing of Soil Moisture)
Open AccessArticle
Sediment Size Effects in Acoustic Doppler Velocimeter-Derived Estimates of Suspended Sediment Concentration
Water 2017, 9(7), 529; https://doi.org/10.3390/w9070529
Received: 16 June 2017 / Revised: 11 July 2017 / Accepted: 11 July 2017 / Published: 16 July 2017
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Abstract
Backscatter output from a 10 MHz acoustic Doppler velocimeter (ADV) was used to quantify suspended sediment concentrations in a laboratory setting using sand-sized particles. The experiments included (a) well-sorted sand samples ranging in size from 0.112 to 0.420 mm, obtained by the sieving [...] Read more.
Backscatter output from a 10 MHz acoustic Doppler velocimeter (ADV) was used to quantify suspended sediment concentrations in a laboratory setting using sand-sized particles. The experiments included (a) well-sorted sand samples ranging in size from 0.112 to 0.420 mm, obtained by the sieving of construction sand, (b) different, known mixtures of these well-sorted fractions, and (c) sieved natural beach sand with median sizes ranging from 0.112 to 0.325 mm. The tested concentrations ranged from 25 to 3000 mg•L−1. The backscatter output was empirically related to concentration and sediment size, and when non-dimensionalized by acoustic wavelength, a dimensionless sediment size gradation coefficient. Size-dependent upper and lower bounds on measurable concentrations were also established empirically. The range of measurable conditions is broad enough to make the approach useful for sand sizes and concentrations commonly encountered in nature. A new method is proposed to determine concentrations in cases of mixed-size sediment suspensions when only calibration data for well-sorted constituent sands are available. This approach could potentially allow better estimates when the suspended load is derived from but is not fully representative of the bed material, and when the size characteristics of the suspended material are varying in time over the period of interest. Differences in results between the construction and beach sands suggest that sediment shape may also need to be considered, and point to the importance of calibrating to sediments encountered at the site of interest. Full article
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Open AccessArticle
An Integrated Method for Interval Multi-Objective Planning of a Water Resource System in the Eastern Part of Handan
Water 2017, 9(7), 528; https://doi.org/10.3390/w9070528
Received: 9 May 2017 / Revised: 28 June 2017 / Accepted: 12 July 2017 / Published: 16 July 2017
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Abstract
In this study, an integrated solving method is proposed for interval multi-objective planning. The proposed method is based on fuzzy linear programming and an interactive two-step method. It cannot only provide objectively optimal values for multiple objectives at the same time, but also [...] Read more.
In this study, an integrated solving method is proposed for interval multi-objective planning. The proposed method is based on fuzzy linear programming and an interactive two-step method. It cannot only provide objectively optimal values for multiple objectives at the same time, but also effectively offer a globally optimal interval solution. Meanwhile, the degree of satisfaction related to different objective functions would be obtained. Then, the integrated solving method for interval multi-objective planning is applied to a case study of planning multi-water resources joint scheduling under uncertainty in the eastern part of Handan, China. The solutions obtained are useful for decision makers in easing the contradiction between supply of multi-water resources and demand from different water users. Moreover, it can provide the optimal comprehensive benefits of economy, society, and the environment. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle
Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)
Water 2017, 9(7), 527; https://doi.org/10.3390/w9070527
Received: 28 April 2017 / Revised: 29 June 2017 / Accepted: 12 July 2017 / Published: 15 July 2017
Cited by 3 | Viewed by 1978 | PDF Full-text (2276 KB) | HTML Full-text | XML Full-text
Abstract
Submerged macrophytes are important structural components of freshwater ecosystems that are widely used as long-term bioindicators for the trophic state of freshwater lakes. Climate change and related rising water temperatures are suspected to affect macrophyte growth and species composition as well as the [...] Read more.
Submerged macrophytes are important structural components of freshwater ecosystems that are widely used as long-term bioindicators for the trophic state of freshwater lakes. Climate change and related rising water temperatures are suspected to affect macrophyte growth and species composition as well as the length of the growing season. Alternative to the traditional ground-based monitoring methods, remote sensing is expected to provide fast and effective tools to map submerged macrophytes at short intervals and over large areas. This study analyses interrelations between spectral signature, plant phenology and the length of growing season as influenced by the variable water temperature. During the growing seasons of 2011 and 2015, remote sensing reflectance spectra of macrophytes and sediment were collected systematically in-situ with hyperspectral underwater spectroradiometer at Lake Starnberg, Germany. The established spectral libraries were used to develop reflectance models. The combination of spectral information and phenologic characteristics allows the development of a phenologic fingerprint for each macrophyte species. By inversion, the reflectance models deliver day and daytime specific spectral signatures of the macrophyte populations. The subsequent classification processing chain allowed distinguishing species-specific macrophyte growth at different phenologic stages. The analysis of spectral signatures within the phenologic development indicates that the invasive species Elodea nuttallii is less affected by water temperature oscillations than the native species Chara spp. and Potamogeton perfoliatus. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle
Field Studies of Microbial Removal from Stormwater by Bioretention Cells with Fly-Ash Amendment
Water 2017, 9(7), 526; https://doi.org/10.3390/w9070526
Received: 15 May 2017 / Revised: 7 July 2017 / Accepted: 13 July 2017 / Published: 15 July 2017
Cited by 2 | Viewed by 1548 | PDF Full-text (373 KB) | HTML Full-text | XML Full-text
Abstract
Microbial pollution in stormwater is a concern in urban areas across the U.S. and is a leading cause of water-quality impairment in the United States. This issue may be addressed through the use of best management practices (BMPs) and target limits for pathogenic [...] Read more.
Microbial pollution in stormwater is a concern in urban areas across the U.S. and is a leading cause of water-quality impairment in the United States. This issue may be addressed through the use of best management practices (BMPs) and target limits for pathogenic indicator species. Bioretention is a commonly used low impact development strategy that addresses this growing pollution problem at the source. Bioretention removal efficiencies have been well studied when considering nutrients and heavy metals, but field-scale treatment data are limited for microbial indicators. The primary objective of this study was to quantify microbial removal by installed bioretention cells with fly-ash amended soils. Three bioretention cells in Grove, Oklahoma were monitored over one and a half years and the removal microbial efficiency was quantified. Overall, removal rates for E. coli, enterococci, and coliphage were highly variable, with mean and standard deviations for removals for each site respectively: E. coli 87%, 35%, and 43%; enterococci 97%, 95%, and 80%; and coliphage 38%, 75%, and 32%. The site with negative removal efficiency appears to have some groundwater intrusion during storm events. Based on this relatively limited data set, these fly-ash amended bioretention cells performed 49% better than those with a sand-only filter media layer currently reported in the literature. Based on this initial field study, it appears that fly-ash amended bioretention cells may be a viable option for enhanced microbial removal from stormwater runoff. Full article
(This article belongs to the Special Issue Additives in Stormwater Filters for Enhanced Pollutant Removal)
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Open AccessArticle
River Stage Modeling by Combining Maximal Overlap Discrete Wavelet Transform, Support Vector Machines and Genetic Algorithm
Water 2017, 9(7), 525; https://doi.org/10.3390/w9070525
Received: 21 May 2017 / Revised: 3 July 2017 / Accepted: 5 July 2017 / Published: 15 July 2017
Cited by 4 | Viewed by 1888 | PDF Full-text (14834 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a river stage modeling approach combining maximal overlap discrete wavelet transform (MODWT), support vector machines (SVMs) and genetic algorithm (GA). The MODWT decomposes original river stage time series into sub-time series (detail and approximation components). The SVM computes daily river [...] Read more.
This paper proposes a river stage modeling approach combining maximal overlap discrete wavelet transform (MODWT), support vector machines (SVMs) and genetic algorithm (GA). The MODWT decomposes original river stage time series into sub-time series (detail and approximation components). The SVM computes daily river stage values using the decomposed sub-time series. The GA searches for the optimal hyperparameters of SVM. The performance of MODWT–SVM models is evaluated using efficiency and effectiveness indices; and compared with that of a single model (multilayer perceptron (MLP) and SVM), discrete wavelet transform (DWT)-based models (DWT–MLP and DWT–SVM) and MODWT–MLP models. The conjunction of MODWT, SVM and GA improves the performance of the SVM model and outperforms the single models. The MODWT–based models using the SVM model enhance model performance and accuracy compared to those of using MLP model. Also, hybrid models coupling MODWT, SVM and GA improve model performance and accuracy in daily river stage modeling as compared with those combined with DWT. The MODWT–SVM model using the Coiflet 12 (c12) mother wavelet, MODWT–SVM-c12, produces the best efficiency and effectiveness among all models. Therefore, the conjunction of MODWT, SVM and GA can be an efficient and effective approach for modeling daily river stages. Full article
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