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Water, Volume 11, Issue 5 (May 2019)

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Cover Story (view full-size image) A computational model for the fluid structure interaction of a buoyant rigid body immersed in a [...] Read more.
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Open AccessArticle
Synthetical Optimization of a Gravity-Driven Irrigation Pipeline Network System with Pressure-Regulating Facilities
Water 2019, 11(5), 1112; https://doi.org/10.3390/w11051112
Received: 20 April 2019 / Revised: 17 May 2019 / Accepted: 23 May 2019 / Published: 27 May 2019
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Abstract
Due to the influence of topographic drops, a large elevation difference often occurs in the middle and lower sections of the main pipe of a gravity-driven irrigation pipe network (GDIPN) system. This elevation difference must be reduced appropriately through pressure reduction facilities (pressure-regulating [...] Read more.
Due to the influence of topographic drops, a large elevation difference often occurs in the middle and lower sections of the main pipe of a gravity-driven irrigation pipe network (GDIPN) system. This elevation difference must be reduced appropriately through pressure reduction facilities (pressure-regulating ponds (PRPs) or pressure-reducing valves (PRVs)). The number and locations of PRPs are crucial factors in regulating and balancing the pressure head of the main pipe of a GDIPN system as well as in reducing the project cost. However, there are few studies on the optimization of this kind of pipe network system. In this paper, first, we generalize such type of GDIPN system, and a simplified mathematical model for such system optimization was established. A genetic algorithm based on a fixed proportion and direct comparison (GA-FPDC) was introduced to solve the model. Two existing projects were tested by the proposed method. The results show that the presented method not only improved the design efficiency and rationality but also greatly decreased the project cost. The presented method is effective and efficient to address optimization design of such GDIPN system problems. Full article
(This article belongs to the Section Water Use and Scarcity)
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Open AccessArticle
Phosphorus Availability and Growth of Benthic Primary Producers in Littoral Lake Sediments: Are Differences Linked to Induced Bank Filtration?
Water 2019, 11(5), 1111; https://doi.org/10.3390/w11051111
Received: 17 April 2019 / Revised: 23 May 2019 / Accepted: 24 May 2019 / Published: 27 May 2019
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Abstract
Submerged macrophytes and periphyton are benthic primary producers that play an important role for several ecosystem functions of lakes. Their growth often depends on the availability of phosphorus (P) in sediments and overlying water. This P availability is assumed to potentially be affected [...] Read more.
Submerged macrophytes and periphyton are benthic primary producers that play an important role for several ecosystem functions of lakes. Their growth often depends on the availability of phosphorus (P) in sediments and overlying water. This P availability is assumed to potentially be affected by induced bank filtration (IBF), a cost-effective method for drinking water production. In this study, we tested whether littoral sediments sampled at sites with high and low influence of IBF in a temperate eutrophic lake used for bank filtration since more than 100 years affects periphyton and macrophyte growth. Sediments differed in aerobic desorbed water-soluble phosphorus (PH2O) and iron (Fe) content and the growth of macrophytes in sediments with a high impact of IBF was lower compared to sediments with low impact of IBF. We also found that P addition to the nutrient solution increased periphyton growth and that periphyton limited macrophyte growth. While these results point to a potential impact of IBF on P availability in sediments that can cascade to benthic primary producers, we could not prove mechanistic links between high rates of IBF and the lower macrophyte growth. Additional research to assure a sustainable application of this valuable drinking water production method is therefore needed. Full article
(This article belongs to the Section Water Quality and Ecosystems)
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Open AccessArticle
Application Research of an Efficient and Stable Boundary Processing Method for the SPH Method
Water 2019, 11(5), 1110; https://doi.org/10.3390/w11051110
Received: 25 April 2019 / Revised: 20 May 2019 / Accepted: 22 May 2019 / Published: 27 May 2019
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Abstract
The boundary truncation of the kernel function affects the numerical accuracy and calculation stability of the smooth particle hydrodynamics (SPH) method and has been one of the key research fields for this method. In this paper, an efficient and stable boundary processing method [...] Read more.
The boundary truncation of the kernel function affects the numerical accuracy and calculation stability of the smooth particle hydrodynamics (SPH) method and has been one of the key research fields for this method. In this paper, an efficient and stable boundary processing method for the SPH method was introduced by adopting an improved boundary interpolation method (i.e., the improved Shepard method) which needs only the sum of direct accumulation for fixed-boundary particles to improve the numerical stability and computational efficiency of the fixed ghost particle method. The improvement effect of the method was demonstrated by comparing it with different interpolation methods using the cases of still water, a wave generated by dam-breaking, and a solitary wave attacking problem with fixed walls and a moveable wall. The results showed that the new boundary processing method for SPH can help remarkably improve the efficiency of calculation and reduce the oscillations of pressure when simulating various flows. Full article
(This article belongs to the Section Hydraulics)
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Open AccessArticle
Variation and Driving Factors of Water Discharge and Sediment Load in Different Regions of the Jinsha River Basin in China in the Past 50 Years
Water 2019, 11(5), 1109; https://doi.org/10.3390/w11051109
Received: 21 April 2019 / Revised: 20 May 2019 / Accepted: 23 May 2019 / Published: 27 May 2019
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Abstract
The Jinsha River is the main source of sediment in the Yangtze River Basin. The variation of water discharge and sediment load not only affects the operation of the cascade reservoirs in the basin but also change the water and sediment conditions into [...] Read more.
The Jinsha River is the main source of sediment in the Yangtze River Basin. The variation of water discharge and sediment load not only affects the operation of the cascade reservoirs in the basin but also change the water and sediment conditions into the Three Gorges Reservoir. The Jinsha River Basin is divided into six regions based on the measured data of hydrological stations. Herein, the variation regularity and driving factors of water discharge and sediment load in the Jinsha River Basin are analyzed in the past 50 years using the Mann–Kendall and Rank Sum Test. Results show that the source of water and sediment in the Jinsha River Basin is different, and the abrupt and trend changes of water discharge and sediment load in different regions are evident different. Changes in precipitation, water and soil conservation projects, and the construction of reservoirs are the main driving factors of sediment load variation. The average annual sediment reduction load in the Jinsha River from 1998 to 2015 is approximately 99.57 × 106 t/y, of which the contributions of water discharge change and human activities to sediment load are 18.9% and 81.1%, respectively. The reduction of sediment load in the Jinsha River Basin can result in evident decrease in the sedimentation of cascade reservoirs, erosion of the downstream channel of the river, and considerable reduction of sediment load into the Three Gorges Reservoir. Full article
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Open AccessArticle
Does Activated Silver Reduce Recontamination Risks in the Reservoirs of Ceramic Water Filters?
Water 2019, 11(5), 1108; https://doi.org/10.3390/w11051108
Received: 18 April 2019 / Revised: 10 May 2019 / Accepted: 24 May 2019 / Published: 27 May 2019
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Abstract
Efforts to provide safe water are challenged by recontamination and regrowth of pathogens in treated water during storage. This study evaluated the potential of metallic silver with a chemically etched surface to reduce recontamination risks during water storage in ceramic water filters. Batch [...] Read more.
Efforts to provide safe water are challenged by recontamination and regrowth of pathogens in treated water during storage. This study evaluated the potential of metallic silver with a chemically etched surface to reduce recontamination risks during water storage in ceramic water filters. Batch experiments were conducted in the laboratory with water storage buckets containing three configurations of varying amounts of silver. Field trials in a rural area in Kenya assessed the effect of the same configurations in the storage buckets of locally produced ceramic pot filters without colloidal silver coating. The tests revealed that the etched silver slightly reduced microbiological recontamination risks during water storage despite the low diffusion of silver ions (<5 µg Ag/L). The effect was strongly influenced by water chemistry parameters. A statistically significant difference in the removal of E. coli (Δ Log Removal Value (LRV) = 0.6) and total coliforms (Δ LRV = 1.7) was found between households using a filter with silver in the water reservoir and those using a filter without silver. Multivariate regression of water handling factors and hygiene practices on filter performance revealed that the presence of silver in the reservoir and cleaning the filter element with a brush were associated with a better filter performance. Full article
(This article belongs to the Section Water Use and Scarcity)
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Open AccessArticle
An Assessment of Groundwater Contamination Risk with Radon Based on Clustering and Structural Models
Water 2019, 11(5), 1107; https://doi.org/10.3390/w11051107
Received: 3 April 2019 / Revised: 21 May 2019 / Accepted: 21 May 2019 / Published: 27 May 2019
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Abstract
There is currently some controversy in the scientific community regarding the efficiency of the water–rock interaction process in the contamination of radon in groundwater. In this study, some difficulties were found in the sampling phase. Many of the water collection points are used [...] Read more.
There is currently some controversy in the scientific community regarding the efficiency of the water–rock interaction process in the contamination of radon in groundwater. In this study, some difficulties were found in the sampling phase. Many of the water collection points are used for human consumption. As such, some municipalities did not want to collaborate. When this natural contaminant is undetectable to the human sense and may cause pulmonary neoplasms in the long term, it is difficult to obtain collaboration from the municipalities concerned. To overcome this controversy, it is important to understand that geogenic, climatic, hydrological, and topographic features may contribute to the effective transfer of radon from rocks to groundwater. In brief, this new approach combines the radon transfer from the geological substrate to the groundwater circulation through hierarchic agglomerative clustering (HAC) and partial least squares-path modeling (PLS-PM) methods. The results show that some lithologies with higher radon production may not always contribute to noticeable groundwater contamination. In this group, the high-fracturing density confirms the recharge efficiency, and the physical-chemical properties of the hydraulic environment (electric conductivity) plays the main role of radon unavailability in the water intended for human consumption. Besides, the hydraulic turnover time of the springs can be considered an excellent radiological indicator in groundwater. In the absence of an anomalous radioactive source near the surface, it means that the high-turnover time of the springs leads to a low-radon concentration in the water. Besides linking high-risk areas with a short period required to free local flow discharges, this study exposes the virtues of a new perspective of a groundwater contamination risk modeling. Full article
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Open AccessEditorial
Transformative Approaches for Sustainable Water Management in the Urban Century
Water 2019, 11(5), 1106; https://doi.org/10.3390/w11051106
Received: 21 May 2019 / Accepted: 22 May 2019 / Published: 27 May 2019
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Abstract
Sustainable Urban Water Management (SUWM) approaches highlighted in this special issue have the potential to contribute to the transformation of urban water systems. The aim of the transformation is to accommodate population and economic growth and at the same time enable a system [...] Read more.
Sustainable Urban Water Management (SUWM) approaches highlighted in this special issue have the potential to contribute to the transformation of urban water systems. The aim of the transformation is to accommodate population and economic growth and at the same time enable a system which is environmentally sustainable and resilient to future challenges such as climate change. These approaches have increasingly entered mainstream dialogue over the last ten years as knowledge on the approaches has developed, and there is an acceptance that there needs to be a change to how urban water systems are designed and operated. However, there are still a range of aspects of these approaches that are maturing and require further research to realize the objectives of SUWM. The issue explored supply-side interventions, such as rainwater harvesting and stormwater harvesting, demand-side interventions, and water storage solutions that have the potential to enable a range of recycling technologies. The issue also highlighted a novel method for better managing the integrity of a conventional sewer system. Furthermore, there are articles that explore methods for integrated assessments, integrated decision making and an exploration of what factors may promote community adoption of technology. Full article
Open AccessArticle
Assessment of Agricultural Drought Considering the Hydrological Cycle and Crop Phenology in the Korean Peninsula
Water 2019, 11(5), 1105; https://doi.org/10.3390/w11051105
Received: 7 April 2019 / Revised: 21 May 2019 / Accepted: 23 May 2019 / Published: 27 May 2019
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Abstract
Hydrological changes attributable to global warming increase the severity and frequency of droughts, which in turn affect agriculture. Hence, we proposed the Standardized Agricultural Drought Index (SADI), which is a new drought index specialized for agriculture and crops, and evaluated current and expected [...] Read more.
Hydrological changes attributable to global warming increase the severity and frequency of droughts, which in turn affect agriculture. Hence, we proposed the Standardized Agricultural Drought Index (SADI), which is a new drought index specialized for agriculture and crops, and evaluated current and expected droughts in the Korean Peninsula. The SADI applies crop phenology to the hydrological cycle, which is a basic element that assesses drought. The SADI of rice and maize was calculated using representative hydrological variables (precipitation, evapotranspiration, and runoff) of the crop growing season. In order to evaluate the effectiveness of SADI, the three-month Standardized Precipitation Index, which is a representative drought index, and rainfed crop yield were estimated together. The performance evaluation of SADI showed that the correlation between rainfed crop yield and SADI was very high compared with that of existing drought index. The results of the assessment of drought over the past three decades provided a good indication of a major drought period and differentiated the results for crops and regions. The results of two future scenarios showed common drought risks in the western plains of North Korea. Successfully validated SADIs could be effectively applied to agricultural drought assessments in light of future climate change, and would be a good example of the water-food nexus approach. Full article
(This article belongs to the Special Issue Study for Ungauged Catchments—Data, Models and Uncertainties)
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Open AccessArticle
A Combined Method for Estimating Continuous Runoff by Parameter Transfer and Drainage Area Ratio Method in Ungauged Catchments
Water 2019, 11(5), 1104; https://doi.org/10.3390/w11051104
Received: 11 April 2019 / Revised: 22 May 2019 / Accepted: 22 May 2019 / Published: 27 May 2019
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Abstract
Continuous runoff needs to be estimated in ungauged catchments to interpret hydrological phenomena and manage water resources. Researchers have used various methods to estimate runoff in ungauged catchments, but few combined different methods to improve the estimation. A model parameter-based method named the [...] Read more.
Continuous runoff needs to be estimated in ungauged catchments to interpret hydrological phenomena and manage water resources. Researchers have used various methods to estimate runoff in ungauged catchments, but few combined different methods to improve the estimation. A model parameter-based method named the parameter transfer (PT) method and a flow-based method of area ratio (AR) were combined and tested in eight catchments in a lake basin. The performance of the PT method depended on the model simulation and donors, which were related to physical and climate characteristics of the catchments. Two AR methods were compared and the results showed that the standard AR method was suitable in this study area with the area ratio between donor and target ranging from 0.46 to 1.41. ENS and R2 values suggested that the PT method used in this study showed a better result than the AR method in 75% of the considered sites, but the total runoff deviation was lower for the standard AR method than that for the PT method. We used the standard AR method weighted by the PT method, and compared three versions weighted with daily, monthly, and average ENS values of the PT and AR methods and one unweighted version. The results of the combined methods were promising. The version weighted with daily ENS performed best and gave improved R2 and daily ENS values for 75% of the receivers. The unweighted combined method performed stable in all sites. The combined method gave better simulation of daily and monthly continuous runoff in ungauged catchments than each individual method. Full article
(This article belongs to the Special Issue Hydrological Processes under Environmental Change)
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Open AccessArticle
Necessity of Acknowledging Background Pollutants in Management and Assessment of Unique Basins
Water 2019, 11(5), 1103; https://doi.org/10.3390/w11051103
Received: 22 April 2019 / Revised: 21 May 2019 / Accepted: 23 May 2019 / Published: 27 May 2019
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Abstract
The limitations of water quality management and assessment methods in China can be ascertained by comparison with other countries. However, it is unreasonable to use a uniform standard to evaluate water quality throughout China because one standard cannot fully account for the regional [...] Read more.
The limitations of water quality management and assessment methods in China can be ascertained by comparison with other countries. However, it is unreasonable to use a uniform standard to evaluate water quality throughout China because one standard cannot fully account for the regional differences in background water quality. This study aimed to provide a basis for environmental water management decision-making. Areas seriously affected by background pollutants were identified by comparing several factors across 31 provinces in China. By coupling an improved export coefficient model (ECM) with a mechanistic model, a suitable pollutant yield coefficient was determined and its rationality was analysed. The export coefficient model was applied to estimate the pollutant (chemical oxygen demand and ammonia nitrogen) output of the basin in 2015. The spatial distribution characteristics of the pollutants were determined by simulating the pollutant outputs of 22 sub-basins and nine water function zones. For the year 2020, the simulation results of pollutant outputs far exceed the sewage discharge limit in water function zones and the pollutant concentration was much higher than the standard. Considering background pollutant outputs, more reasonable sewage discharge limit and water quality evaluation method are proposed. Full article
(This article belongs to the Special Issue Water Resources Management Models for Policy Assessment)
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Open AccessArticle
Development of Climate Data Bias Corrector (CDBC) Tool and Its Application over the Agro-Ecological Zones of India
Water 2019, 11(5), 1102; https://doi.org/10.3390/w11051102
Received: 22 April 2019 / Revised: 12 May 2019 / Accepted: 20 May 2019 / Published: 27 May 2019
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Abstract
The use of global and regional climate models has been increasing in the past few decades, in order to analyze the future of natural resources and the socio-economic aspects of climate change. However, these climate model outputs can be quite biased, which makes [...] Read more.
The use of global and regional climate models has been increasing in the past few decades, in order to analyze the future of natural resources and the socio-economic aspects of climate change. However, these climate model outputs can be quite biased, which makes it challenging to use them directly for analysis purpose. Therefore, a tool named Climate Data Bias Corrector was developed to correct the bias in climatic projections of historical and future periods for three primary climatic variables—rainfall, temperature (maximum and minimum), and solar radiation. It uses the quantile mapping approach, known for its efficiency and low computational cost for bias correction. Its Graphical User Interface (GUI) was made to be feasible to take input and give output in commonly used file formats—comma and tab delimited file formats. It also generates month-wise cumulative density function (CDF) plot of a random station/grid to allow the user to investigate the effectiveness of correction statistically. The tool was verified with a case study on several agro-ecological zones of India and found to be efficient. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle
A Greedy Algorithm for Optimal Sensor Placement to Estimate Salinity in Polder Networks
Water 2019, 11(5), 1101; https://doi.org/10.3390/w11051101
Received: 24 April 2019 / Revised: 17 May 2019 / Accepted: 21 May 2019 / Published: 27 May 2019
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Abstract
We present a systematic approach for salinity sensor placement in a polder network, where the objective is to estimate the unmeasured salinity levels in the main polder channels. We formulate this problem as optimization of the estimated salinity levels using root mean square [...] Read more.
We present a systematic approach for salinity sensor placement in a polder network, where the objective is to estimate the unmeasured salinity levels in the main polder channels. We formulate this problem as optimization of the estimated salinity levels using root mean square error (RMSE) as the “goodness of fit” measure. Starting from a hydrodynamic and salt transport model of the Lissertocht catchment (a low-lying polder in the Netherlands), we use principal component analysis (PCA) to produce a low-order PCA model of the salinity distribution in the catchment. This model captures most of the relevant salinity dynamics and is capable of reconstructing the spatial and temporal salinity variation of the catchment. Just using three principal components (explaining 93% of the variance of the dataset) for the low-order PCA model, three optimally placed sensors with a greedy algorithm make the placement robust for modeling and measurement errors. The performance of the sensor placement for salinity reconstruction is evaluated against the detailed hydrodynamic and salt transport model and is shown to be close to the global optimum found by an exhaustive search with a RMSE of 82.2 mg/L. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessArticle
In Situ Nutrient Removal from Rural Runoff by A New Type Aerobic/Anaerobic/Aerobic Water Spinach Wetlands
Water 2019, 11(5), 1100; https://doi.org/10.3390/w11051100
Received: 2 May 2019 / Revised: 23 May 2019 / Accepted: 24 May 2019 / Published: 26 May 2019
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Abstract
Rural runoff with abundant nutrients has become a great threat to aquatic environment. Hence, more and more attention has been focused on nutrients removal. In this study, an improved aerobic/anaerobic/aerobic three-stage water spinach constructed wetland (O-A-O-CW) was used to improve the removal of [...] Read more.
Rural runoff with abundant nutrients has become a great threat to aquatic environment. Hence, more and more attention has been focused on nutrients removal. In this study, an improved aerobic/anaerobic/aerobic three-stage water spinach constructed wetland (O-A-O-CW) was used to improve the removal of nitrogen and phosphorus of rural runoff. The removal rate of the target pollutants in O-A-O-CW was compared with the common matrix flow wetland as well as the no-plant wetland. The results showed that the O-A-O-CW significantly increased the chemical oxygen demand, total phosphorus, ammonium-nitrogen, nitrate, and total nitrogen removal rate, and the corresponding removal rate was 55.85%, 81.70%, 76.64%, 89.78%, and 67.68%, respectively. Moreover, the best hydraulic condition of the wetland, including hydraulic retention time and hydraulic loading, was determined, which were 2 days and 0.45 m3·m−2·day−1, respectively. Furthermore, the removal mechanism of the constructed wetland was thoroughly studied, which included the adsorption of nitrogen and phosphorus by the matrix and water spinach, and the nitrification and denitrification by the bacteria. The results demonstrated that the mechanisms of nitrogen removal in the new type wetland were principally by the nitrification and denitrification process. Additionally, adsorption and precipitation by the matrix are mainly responsible for phosphorus removal. These results suggested that the new O-A-O-CW can efficiently removal nutrients and enhance the water quality of the rural runoff. Full article
(This article belongs to the Special Issue Urban Water Accounting)
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Open AccessArticle
Ordered Mesoporous Carbons for Adsorption of Paracetamol and Non-Steroidal Anti-Inflammatory Drugs: Ibuprofen and Naproxen from Aqueous Solutions
Water 2019, 11(5), 1099; https://doi.org/10.3390/w11051099
Received: 18 April 2019 / Revised: 21 May 2019 / Accepted: 22 May 2019 / Published: 25 May 2019
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Abstract
The adsorption of paracetamol and non-steroidal anti-inflammatory drugs (ibuprofen and naproxen) on ordered mesoporous carbons (OMC) and, for comparison, on commercial activated carbon, were investigated in this work. OMC adsorbents were obtained by the soft-templating method and were characterized by low-temperature nitrogen adsorption [...] Read more.
The adsorption of paracetamol and non-steroidal anti-inflammatory drugs (ibuprofen and naproxen) on ordered mesoporous carbons (OMC) and, for comparison, on commercial activated carbon, were investigated in this work. OMC adsorbents were obtained by the soft-templating method and were characterized by low-temperature nitrogen adsorption and scanning electron microscopy (SEM). The effects of contact time and initial concentration of organic adsorbates on the adsorption were studied. The contact time to reach equilibrium for maximum adsorption was 360 min for all the studied adsorbates. The adsorption mechanism was found to fit pseudo-second-order and intra particle-diffusion models. Freundlich, Langmuir and Langmuir-Freundlich isotherm models were used to analyze equilibrium adsorption data. Based on the obtained experimental data, the adsorption isotherm in the applied concentration range for all the studied adsorbates was well represented by the Freundlich-Langmuir model. The adsorption ability of ordered mesoporous carbon materials was much higher for paracetamol and naproxen in comparison to commercial activated carbon. The removal efficiency for ibuprofen was significantly lower than for other studied pharmaceuticals and comparable for all adsorbents. Theoretical calculations made it possible to obtain optimized chemical structures of (S)-naproxen, ibuprofen, and paracetamol molecules. Knowledge of charge distributions of these adsorbate molecules can be helpful to explain why paracetamol and naproxen can react more strongly with the surface of adsorbents with a large numbers of acidic groups compared to ibuprofen facilitating more efficient adsorption of these pharmaceuticals on ordered mesoporous carbons. Full article
(This article belongs to the Section Water and Wastewater Treatment)
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Open AccessArticle
Forecasting Groundwater Table in a Flood Prone Coastal City with Long Short-term Memory and Recurrent Neural Networks
Water 2019, 11(5), 1098; https://doi.org/10.3390/w11051098
Received: 9 April 2019 / Revised: 21 May 2019 / Accepted: 22 May 2019 / Published: 25 May 2019
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Abstract
Many coastal cities are facing frequent flooding from storm events that are made worse by sea level rise and climate change. The groundwater table level in these low relief coastal cities is an important, but often overlooked, factor in the recurrent flooding these [...] Read more.
Many coastal cities are facing frequent flooding from storm events that are made worse by sea level rise and climate change. The groundwater table level in these low relief coastal cities is an important, but often overlooked, factor in the recurrent flooding these locations face. Infiltration of stormwater and water intrusion due to tidal forcing can cause already shallow groundwater tables to quickly rise toward the land surface. This decreases available storage which increases runoff, stormwater system loads, and flooding. Groundwater table forecasts, which could help inform the modeling and management of coastal flooding, are generally unavailable. This study explores two machine learning models, Long Short-term Memory (LSTM) networks and Recurrent Neural Networks (RNN), to model and forecast groundwater table response to storm events in the flood prone coastal city of Norfolk, Virginia. To determine the effect of training data type on model accuracy, two types of datasets (i) the continuous time series and (ii) a dataset of only storm events, created from observed groundwater table, rainfall, and sea level data from 2010–2018 are used to train and test the models. Additionally, a real-time groundwater table forecasting scenario was carried out to compare the models’ abilities to predict groundwater table levels given forecast rainfall and sea level as input data. When modeling the groundwater table with observed data, LSTM networks were found to have more predictive skill than RNNs (root mean squared error (RMSE) of 0.09 m versus 0.14 m, respectively). The real-time forecast scenario showed that models trained only on storm event data outperformed models trained on the continuous time series data (RMSE of 0.07 m versus 0.66 m, respectively) and that LSTM outperformed RNN models. Because models trained with the continuous time series data had much higher RMSE values, they were not suitable for predicting the groundwater table in the real-time scenario when using forecast input data. These results demonstrate the first use of LSTM networks to create hourly forecasts of groundwater table in a coastal city and show they are well suited for creating operational forecasts in real-time. As groundwater table levels increase due to sea level rise, forecasts of groundwater table will become an increasingly valuable part of coastal flood modeling and management. Full article
(This article belongs to the Special Issue Urban Water Management and Urban Flooding)
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Open AccessArticle
Scour Induced by Single and Twin Propeller Jets
Water 2019, 11(5), 1097; https://doi.org/10.3390/w11051097
Received: 27 April 2019 / Revised: 13 May 2019 / Accepted: 23 May 2019 / Published: 25 May 2019
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Abstract
Single and twin ship propeller jets produce scour holes with deposition dune. The scour hole has a maximum depth at a particular length downstream within the propeller jet. Existing equations are available to predict maximum scour depth and the corresponding scour length downstream. [...] Read more.
Single and twin ship propeller jets produce scour holes with deposition dune. The scour hole has a maximum depth at a particular length downstream within the propeller jet. Existing equations are available to predict maximum scour depth and the corresponding scour length downstream. Experiments conducted with various physical propeller models, rotational speeds, propeller-to-propeller distances and bed clearances are presented. The measurements allowed a better understanding of the mechanism of temporal scour and deposition formation for scour caused by single-propeller and twin-propeller. Results show that the propeller jet scour profiles can be divided into three zones, which are the small scour hole, primary scour hole and deposition dune. An empirical 2D scour model is proposed to predict the scour profile for both a single-propeller and twin-propeller using a Gaussian normal distribution. Full article
(This article belongs to the Special Issue Experimental, Numerical and Field Approaches to Scour Research)
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Open AccessArticle
Seasonal Drought Pattern Changes Due to Climate Variability: Case Study in Afghanistan
Water 2019, 11(5), 1096; https://doi.org/10.3390/w11051096
Received: 20 April 2019 / Revised: 16 May 2019 / Accepted: 23 May 2019 / Published: 25 May 2019
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Abstract
We assessed the changes in meteorological drought severity and drought return periods during cropping seasons in Afghanistan for the period of 1901 to 2010. The droughts in the country were analyzed using the standardized precipitation evapotranspiration index (SPEI). Global Precipitation Climatology Center rainfall [...] Read more.
We assessed the changes in meteorological drought severity and drought return periods during cropping seasons in Afghanistan for the period of 1901 to 2010. The droughts in the country were analyzed using the standardized precipitation evapotranspiration index (SPEI). Global Precipitation Climatology Center rainfall and Climate Research Unit temperature data both at 0.5° resolutions were used for this purpose. Seasonal drought return periods were estimated using the values of the SPEI fitted with the best distribution function. Trends in climatic variables and SPEI were assessed using modified Mann–Kendal trend test, which has the ability to remove the influence of long-term persistence on trend significance. The study revealed increases in drought severity and frequency in Afghanistan over the study period. Temperature, which increased up to 0.14 °C/decade, was the major factor influencing the decreasing trend in the SPEI values in the northwest and southwest of the country during rice- and corn-growing seasons, whereas increasing temperature and decreasing rainfall were the cause of a decrease in SPEI during wheat-growing season. We concluded that temperature plays a more significant role in decreasing the SPEI values and, therefore, more severe droughts in the future are expected due to global warming. Full article
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Open AccessArticle
Impact Analysis of Slope on the Head Loss of Gas-Liquid Two-Phase Flow in Siphon Pipe
Water 2019, 11(5), 1095; https://doi.org/10.3390/w11051095
Received: 25 April 2019 / Revised: 18 May 2019 / Accepted: 22 May 2019 / Published: 25 May 2019
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Abstract
Through an analysis of the head loss of the gas–liquid two-phase flow in a siphon pipe, this paper measures the bubble velocity, pressure drop, and gas fraction under various conditions. The influence of varied head, gradient, and installation heights of the pipe on [...] Read more.
Through an analysis of the head loss of the gas–liquid two-phase flow in a siphon pipe, this paper measures the bubble velocity, pressure drop, and gas fraction under various conditions. The influence of varied head, gradient, and installation heights of the pipe on the air mass movement, head loss, and resistance coefficient of the gas–liquid two-phrase flow is analyzed on the basis of the test results. The results show that the bubble velocity reaches its minimum on the flat slope, and the velocity on the positive slope is higher than that on the reverse slope. The head loss of pipelines in both the positive slope and reverse slope increases as the gradient increases, while the head loss on the reverse slope is larger than that on the positive slope under the same gradient. When the gas fraction α is between 8% and 30%, the resistance coefficient λm is related to the gradient, gas fraction, and the Reynolds number Re. Furthermore, λm is proportionate to α and inversely proportionate to i of the bottom slope and the Re number. The calculation formula of the resistance coefficient λm under various gradients within the scope of the above gas fraction is derived on the basis of the test data, while the relative error is controlled within the allowable range. Full article
(This article belongs to the Section Hydraulics)
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Open AccessArticle
An Optimization-Evaluation Agricultural Water Planning Approach Based on Interval Linear Fractional Bi-Level Programming and IAHP-TOPSIS
Water 2019, 11(5), 1094; https://doi.org/10.3390/w11051094
Received: 5 April 2019 / Revised: 3 May 2019 / Accepted: 20 May 2019 / Published: 24 May 2019
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Abstract
In this study, an interval linear fractional bi-level programming (ILFBP) model was developed for managing irrigation-water resources under uncertainty. The ILFBP can fully address system fairness, uncertainties, and the leader–follower relationship of decision makers in the optimization process, which can better reflect the [...] Read more.
In this study, an interval linear fractional bi-level programming (ILFBP) model was developed for managing irrigation-water resources under uncertainty. The ILFBP can fully address system fairness, uncertainties, and the leader–follower relationship of decision makers in the optimization process, which can better reflect the complexity of real decision-making process and help formulate reasonable water policies. An interactive fuzzy coordination algorithm based on satisfaction degree was introduced to solve the ILFBP model. In order to evaluate the applicability of optimization schemes, the interval analytic hierarchy process (IAHP) and the interval technique for order preference by similarity to an ideal solution (TOPSIS) method were integrated as IAHP-TOPSIS. To verify its validity, the developed optimization-evaluation framework was applied to an irrigation water management case study in the middle reaches of the Shiyang River Basin, located in the northwest China. The ILFBP model results show that the total water allocation is [6.73, 7.37] × 108 m3, saving nearly 0.9 × 108 m3 more than the current situation. The benefit per unit of water is [2.38, 2.95] yuan/m3, nearly 0.4 yuan/m3 more than the status quo, and the Gini coefficient is within a reasonable range of [0.35, 0.38]. The ILFBP model can well balance economic benefits and system fairness. Through the evaluation bases on IAHP-TOPSIS, the results of ILFBP show better water allocation effects and applicability than the other two models in this study area. Furthermore, due to various characteristics such as geographical location, population and area, there are three irrigation districts, Xiying, Donghe, and Qinghe, showing higher importance than others when considering regional water allocation. These findings can provide useful information for limited water resource managers and help decision makers determine effective alternatives of water resource planning under uncertainty. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessArticle
Optimization of Horseradish Peroxidase Catalytic Degradation for 2-Methyl-6-Ethylaniline Removal Using Response Surface Methodology
Water 2019, 11(5), 1093; https://doi.org/10.3390/w11051093
Received: 8 May 2019 / Revised: 21 May 2019 / Accepted: 22 May 2019 / Published: 24 May 2019
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Abstract
For optimizing the reaction conditions of 2-methyl-6-ethylaniline (MEA) degradation catalyzed by horseradish peroxidase (HRP), a response surface methodology with three factors and three levels was used in this research to establish a regression model, a ternary quadratic polynomial, in order to analyze temperature, [...] Read more.
For optimizing the reaction conditions of 2-methyl-6-ethylaniline (MEA) degradation catalyzed by horseradish peroxidase (HRP), a response surface methodology with three factors and three levels was used in this research to establish a regression model, a ternary quadratic polynomial, in order to analyze temperature, H2O2 concentration and pH effects on MEA removal efficiency. The results showed that the regression model was significant (p < 0.0001), fitted well with experimental data and had a high degree of reliability and accuracy, and the data were reasonable with low errors. By analyzing interactions and solving the regression model, the maximum MEA removal efficiency was 97.90%, and the optimal conditions were defined as follows: pH 5.02, H2O2 concentration 13.41mM, and temperature 30.95 °C. Under the optimal conditions, the average MEA removal efficiency obtained from the experiments was 97.56%. This research can provide reference for the treatment of actual acetochlor industrial wastewater. Full article
(This article belongs to the Section Water and Wastewater Treatment)
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Open AccessFeature PaperArticle
Linking Water Scarcity to Mental Health: Hydro–Social Interruptions in the Lake Urmia Basin, Iran
Water 2019, 11(5), 1092; https://doi.org/10.3390/w11051092
Received: 29 March 2019 / Revised: 17 May 2019 / Accepted: 21 May 2019 / Published: 24 May 2019
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Abstract
Alterations of water flows resulting from the manifestation of powerful hydro–social imaginaries often produce an uneven distribution of burdens and benefits for different social groups or regions, reflecting their social and political power. Marginalized regions can suffer manufactured territorialized water scarcity, which disturbs [...] Read more.
Alterations of water flows resulting from the manifestation of powerful hydro–social imaginaries often produce an uneven distribution of burdens and benefits for different social groups or regions, reflecting their social and political power. Marginalized regions can suffer manufactured territorialized water scarcity, which disturbs the natural, economic and socio-political order of water users, and as this article shows, inevitably affects their psychological wellbeing. Set in the context of the surroundings of Lake Urmia in Iran, once one of the largest hypersaline lakes in the world and now a severely degraded ecosystem mainly as a result of water overuse in its watershed, this article explores how and through which pathways this manufactured water scarcity impacted the mental health of the water users in the region. The research findings reveal that alterations in this local hydro–social territory and the resulting biophysical, financial and social changes, as well as impacts on physical health of water users, relate to chronic psychological stress, social isolation, intra-community conflicts, despair, hopelessness, depression and anxiety. Full article
(This article belongs to the Special Issue Critical Water Resource Geography)
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Open AccessArticle
Achieving Urban Stormwater Mitigation Goals on Different Land Parcels with a Capacity Trading Approach
Water 2019, 11(5), 1091; https://doi.org/10.3390/w11051091
Received: 5 May 2019 / Revised: 20 May 2019 / Accepted: 21 May 2019 / Published: 24 May 2019
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Abstract
Building Green Infrastructures (GIs) to reduce stormwater runoff has been recognized as an effective approach to mitigate the negative impact of urban sprawl. Due to the significant differences in urban land use, some Land Parcels (LPs) may have difficulty in building enough GIs [...] Read more.
Building Green Infrastructures (GIs) to reduce stormwater runoff has been recognized as an effective approach to mitigate the negative impact of urban sprawl. Due to the significant differences in urban land use, some Land Parcels (LPs) may have difficulty in building enough GIs to meet stormwater mitigation goals. In this paper, we proposed a Capacity Trading (CT) approach that allows some LPs to trade their extra runoff retention capacities with LPs that have building difficulties, so that they can jointly reach the overall mitigation goal together. The rationale behind CT is that, to avoid potential penalties, it may be more economical for some LPs to ‘buy’ credit rather than to ‘build’ GIs. A case study was used to demonstrate CT operations for two trading scales: (1) CT within neighboring LPs (i.e., CT-1), and (2) CT within 20 m-radius LPs (i.e., CT-2). A GI implementation baseline intensity was set up firstly by treating the whole study area as one entity to reach a specified stormwater runoff control target; individual LPs were then examined for their GI building capacities, which may be deficit or surplus against the target. Results showed that the number and area of deficit LPs were reduced significantly through either CT scales; the number of deficit LPs was reduced from 139 to 97 with CT-1 and 78 with CT-2, and the deficit area was reduced from 649 ha to 558 with CT-1 and 478 ha with CT-2, respectively. The proposed method assumes LPs as the basic planning unit and encourages some stakeholders to maximize their GI building potential to compensate for those with disadvantages. The economic incentives for conducting CT among different LPs in urban area can help achieve stormwater mitigation goals more economically and flexibly. Some coordination among LPs in GI implementation is necessary, which presents both opportunities and challenges for city management. Full article
(This article belongs to the Special Issue Advances of Low Impact Development Practices in Urban Watershed)
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Open AccessArticle
Impact Assessment of Future Climate Change on Streamflows Upstream of Khanpur Dam, Pakistan using Soil and Water Assessment Tool
Water 2019, 11(5), 1090; https://doi.org/10.3390/w11051090
Received: 6 February 2019 / Revised: 8 April 2019 / Accepted: 9 April 2019 / Published: 24 May 2019
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Abstract
The study aims to evaluate the long-term changes in meteorological parameters and to quantify their impacts on water resources of the Haro River watershed located on the upstream side of Khanpur Dam in Pakistan. The climate data was obtained from the NASA Earth [...] Read more.
The study aims to evaluate the long-term changes in meteorological parameters and to quantify their impacts on water resources of the Haro River watershed located on the upstream side of Khanpur Dam in Pakistan. The climate data was obtained from the NASA Earth Exchange Global Daily Downscaled Projection (NEX-GDDP) for MIROC-ESM model under two Representative Concentration Pathway (RCP) scenarios. The model data was bias corrected and the performance of the bias correction was assessed statistically. Soil and Water Assessment Tool was used for the hydrological simulation of watershed followed by model calibration using Sequential Uncertainty Fitting version-2. The study is useful for devising strategies for future management of Khanpur Dam. The study indicated that in the future, at Murree station (P-1), the maximum temperature, minimum temperature and precipitation were anticipated to increase from 3.1 °C (RCP 4.5) to 4.0 °C (RCP 8.5), 3.2 °C (RCP 4.5) to 4.3 °C (RCP 8.5) and 8.6% to 13.5% respectively, in comparison to the baseline period. Similarly, at Islamabad station (P-2), the maximum temperature, minimum temperature and precipitation were projected to increase from 3.3 °C (RCP 4.5) to 4.1 °C (RCP 8.5), 3.3 °C (RCP 4.5) to 4.2 °C (RCP 8.5) and 14.0% to 21.2% respectively compared to baseline period. The streamflows at Haro River basin were expected to rise from 8.7 m3/s to 9.3 m3/s. Full article
(This article belongs to the Special Issue Evaluating Hydrological Responses to Climate Change)
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Open AccessArticle
Characteristics of Stormwater Quality in Singapore Catchments in 9 Different Types of Land Use
Water 2019, 11(5), 1089; https://doi.org/10.3390/w11051089
Received: 13 April 2019 / Revised: 16 May 2019 / Accepted: 20 May 2019 / Published: 24 May 2019
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Abstract
Stormwater quality is well known for its highly stochastic nature and not necessarily well explained by mechanistic urban build up and wash off models. Therefore, local empirical data (based on land use) are an essential compliment to statistical analyses of global data. This [...] Read more.
Stormwater quality is well known for its highly stochastic nature and not necessarily well explained by mechanistic urban build up and wash off models. Therefore, local empirical data (based on land use) are an essential compliment to statistical analyses of global data. This paper reports on a large-scale monitoring of the 12 key water quality parameters of suspended solids, nutrients, and heavy metals for stormwater runoff in urban discharges from nine urban land uses with varying sizes in Singapore. It was found that, in general, the average of the event mean concentrations for total nitrogen, total phosphorus, total organic carbon, total suspended solids (TSS), and phosphate in parkland land use were higher than the other eight studied land uses. Based on Pearson’s correlation analysis, significant correlation between pairs of water quality parameters was observed. Particularly, there was significant correlation between TSS and most of the other tested water quality parameters in all land uses. A pollutant data set from this study will assist in developing appropriate stormwater quality models, guide the establishment of stormwater treatment objectives and preliminary designs for Singapore catchments, as well as provide an essential complement to statistical analyses of global data for stormwater characteristics. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessArticle
Characterizing Land Use Impacts on Channel Geomorphology and Streambed Sedimentological Characteristics
Water 2019, 11(5), 1088; https://doi.org/10.3390/w11051088
Received: 3 April 2019 / Revised: 10 May 2019 / Accepted: 12 May 2019 / Published: 24 May 2019
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Abstract
Land use can radically degrade stream physical habitat via alterations to channel geomorphology and sedimentological characteristics. However, independent and combined influences such as those of agricultural and urban land use practices on channel geomorphology and substrate composition remain poorly understood. To further understanding [...] Read more.
Land use can radically degrade stream physical habitat via alterations to channel geomorphology and sedimentological characteristics. However, independent and combined influences such as those of agricultural and urban land use practices on channel geomorphology and substrate composition remain poorly understood. To further understanding of mixed land use influence on stream physical habitat, an intensive, 56 km hydrogeomorphological assessment was undertaken in a representative mixed land use watershed located in Midwestern USA. Sub-objectives included quantitative characterization of (1) channel geomorphology, (2) substrate frequency and embeddedness, and (3) relationships between land use, channel geomorphology, and substrate frequency and embeddedness. Channel geomorphology, and stream substrate data were directly measured at survey transects (n = 561) every 100 m of the entire 56 km distance of the reference stream. Observed data were averaged within five sub-basins (Sites #1 to #5) nested across an agricultural-urban land use gradient. Multiple regression results showed agricultural and urban land use explained nearly all of the variance in average width to depth ratios (R2 = 0.960; p = 0.020; n = 5), and maximum bank angle (R2 = 0.896; p = 0.052; n = 5). Streambed substrate samples of pools indicated significantly (p < 0.001) increased substrate embeddedness at agricultural Site #1 (80%) located in the headwaters and urban Site #5 (79%) located in the lower reaches compared to rural-urban Sites #2 to #4 (39 to 57%) located in the mid-reaches of the study stream. Streambed substrate embeddedness samples of riffles that ranged from 51 to 72% at Sites #1 and #5, and 27 to 46% at Sites #2 to #4 were significantly different between sites (p = 0.013). Percent embeddedness increased with downstream distance by 5% km−1 with the lower urban reaches indicating symptoms of urban stream syndrome linked to degraded riffle habitat. Collectively, observed alterations to channel morphology and substrate composition point to land use alterations to channel geomorphology metrics correlated with increased substrate embeddedness outside of mid-reaches where bedrock channel constraints accounted for less than 3% of substrate frequency. Results from this study show how a hydrogeomorphological assessment can help elucidate casual factors, target critical source areas, and thus, guide regional stream restoration efforts of mixed-land-use watersheds. Full article
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Open AccessArticle
An Improved Genetic Algorithm for Optimal Layout of Flow Meters and Valves in Water Network Partitioning
Water 2019, 11(5), 1087; https://doi.org/10.3390/w11051087
Received: 3 April 2019 / Revised: 1 May 2019 / Accepted: 16 May 2019 / Published: 24 May 2019
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Abstract
The paradigm of “divide and conquer” has been well used in Water Distribution Systems (WDSs) zoning planning in recent years. Indeed, Water Network Partitioning (WNP) has played an irreplaceable role in leakage control and pressure management; meanwhile it also has certain drawbacks, such [...] Read more.
The paradigm of “divide and conquer” has been well used in Water Distribution Systems (WDSs) zoning planning in recent years. Indeed, Water Network Partitioning (WNP) has played an irreplaceable role in leakage control and pressure management; meanwhile it also has certain drawbacks, such as reduction of the supply reliability of the pipe network system and increased terminal dead water, as a result of the closure of the pipe section. In this paper, an improvement is made to the method proposed by Di Nardo et al. (2013) for optimal location of flow meters and valves. Three improvements to the genetic algorithm are proposed in this work for better and faster optimization in the dividing phase of WNP: preliminary hydraulic analysis which reduces the number of decision variables; modifications to the crossover mechanism to protect the superior individuals in the later stage; and boundary pipe grouping and mutation based on the pipe importance. The objective function considers the master–subordinate relationship when minimizing the number of flow meters and the difference of hydraulic state compared to original WDS. Another objective function of minimizing the deterioration of water quality compared to original WDS is also evaluated. The proposed method is applied for the WNP in a real WDS. Results show that it plays an effective role in the optimization of layout of the flow meters and valves in WNP. Full article
(This article belongs to the Special Issue Advances in Modeling and Management of Urban Water Networks)
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Open AccessArticle
Methane Emissions Driven by Adding a Gradient of Ethanol as Carbon Source in Integrated Vertical-Flow Constructed Wetlands
Water 2019, 11(5), 1086; https://doi.org/10.3390/w11051086
Received: 14 March 2019 / Revised: 22 April 2019 / Accepted: 23 April 2019 / Published: 24 May 2019
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Abstract
This work aims to investigate the methane emissions from integrated vertical-flow constructed wetlands (IVCWs) when ethanol is added as an external carbon source. In this study, a gradient of ethanol (0, 2, 4, 8, 16 and 32 mmol/L) was added as the carbon [...] Read more.
This work aims to investigate the methane emissions from integrated vertical-flow constructed wetlands (IVCWs) when ethanol is added as an external carbon source. In this study, a gradient of ethanol (0, 2, 4, 8, 16 and 32 mmol/L) was added as the carbon source in an IVCW planted with Cyperus alternifolius L. The results showed that the methane emission flux at an ethanol concentration of 32 mmol/L was 32.34 g CH4 m−2 day−1 less than that of the control experiment (0 mmol/L) and that the methane emission flux at an ethanol concentration of 16 mmol/L was 5.53 g CH4 m−2 day−1 less than that at 0 mmol/L. In addition, variations in the water quality driven by the different ethanol concentrations were found, with a redox potential range of −64 mV to +30 mV, a pH range of 6.6–6.9, a chemical oxygen demand (COD) removal rate range of 41% to 78%, and an ammonia nitrogen removal rate range of 59% to 82% after the ethanol addition. With the average CH4-C/TOC (%) value of 35% driven by ethanol, it will be beneficial to understand that CH4-C/TOC can be considered an ecological indicator of anthropogenic methanogenesis from treatment wetlands when driven by carbon sources or carbon loading. It can be concluded that adding ethanol as an external carbon source can not only meet the water quality demand of the IVCW treatment system but also stimulate and increase the average CH4 emissions from IVCWs by 23% compared with the control experiment. This finding indicates that an external carbon source can stimulate more CH4 emissions from IVCWs and shows the importance of carbon sources during sewage treatment processes when considering greenhouse emissions from treated wetlands. Full article
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Open AccessArticle
Simulation of Water Resources Carrying Capacity in Xiong’an New Area Based on System Dynamics Model
Water 2019, 11(5), 1085; https://doi.org/10.3390/w11051085
Received: 22 April 2019 / Revised: 21 May 2019 / Accepted: 22 May 2019 / Published: 24 May 2019
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Abstract
In order to comprehensively evaluate the water resources carrying capacity in Xiong’an New Area, a system dynamics (SD) model was established to evaluate the regional water resources carrying capacity, for which several scenarios were designed: the original development scenario, the accelerated industrialization scenario, [...] Read more.
In order to comprehensively evaluate the water resources carrying capacity in Xiong’an New Area, a system dynamics (SD) model was established to evaluate the regional water resources carrying capacity, for which several scenarios were designed: the original development scenario, the accelerated industrialization scenario, the environmental governance scenario, and the optimization development scenario. The results show that, compared with the original development scenario, the water resources carrying capacity in Xiong’an New Area can be improved in other scenarios, but a water supply and demand gap will be generated due to the lack of groundwater overdraft and a water transfer project. In 2026, under the accelerated industrialization scenario, the population carrying capacity will be 2.652 million, and the water supply and demand gap will be 1.13 × 108 m3; under the environmental governance scenario, the population carrying capacity will be 2.36 million, and the water supply and demand gap will be 0.44 × 108 m3; under the optimal development scenario, the population carrying capacity will be 2.654 million, and since the supply of water resources will be greater than the demand, there will not be a gap between supply and demand, making it the most feasible scenario to effectively alleviate the tension between industry restructuring, environmental management, and water resources development and utilization. The findings of this study can provide reference and decision support for optimizing regional water resources allocation and enhancing water resources carrying capacity in Xiong’an New Area. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessArticle
Water Footprint of Crops on Rhodes Island
Water 2019, 11(5), 1084; https://doi.org/10.3390/w11051084
Received: 7 April 2019 / Revised: 19 May 2019 / Accepted: 21 May 2019 / Published: 24 May 2019
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Abstract
The aim of this paper is to evaluate the water footprints (WFs) of all the main crops on Rhodes island at a municipal unit (MU) scale, as well as for the area of the island as a whole. WF estimations are made with [...] Read more.
The aim of this paper is to evaluate the water footprints (WFs) of all the main crops on Rhodes island at a municipal unit (MU) scale, as well as for the area of the island as a whole. WF estimations are made with a distinction of rainfed and irrigated crops, using CROPWAT 8.0. Rainfed crops and the drip irrigation method are predominant in the study area, which faces water scarcity issues. Furthermore, a reduction factor in plant coefficients is introduced, to adapt to the drip irrigation technique. From the findings obtained, useful conclusions are drawn regarding the most water-demanding crops, but also the type of their WF component (blue/green/gray). In all categories of crops, there are large fluctuations across MUs, mainly due to the different yields. Higher WF values occur for rainfed and irrigated olives, which constitute the predominant crop, followed by hard and soft wheat. WF is a useful indicator identifying which crops require improvement or restructuring in a study area, and quantifies the exact volumes of water, which is a useful element in the formulation of agricultural policy in the context of sustainable water resources management. Full article
(This article belongs to the Section Water Use and Scarcity)
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Open AccessArticle
Clogging of Infiltration Basin and Its Impact on Suspended Particles Transport in Unconfined Sand Aquifer: Insights from a Laboratory Study
Water 2019, 11(5), 1083; https://doi.org/10.3390/w11051083
Received: 28 April 2019 / Revised: 16 May 2019 / Accepted: 20 May 2019 / Published: 24 May 2019
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Abstract
A laboratory study was undertaken to investigate the physical clogging of a sand medium by injecting suspended particles (SP), with diameters ranging from 0.03 to 63.41 μm, into an infiltration basin, which was installed in a sand tank under the condition of constant [...] Read more.
A laboratory study was undertaken to investigate the physical clogging of a sand medium by injecting suspended particles (SP), with diameters ranging from 0.03 to 63.41 μm, into an infiltration basin, which was installed in a sand tank under the condition of constant head. The hydraulic conductivity (K) of the saturated porous medium was found to have decreased by 27% because of re-arrangement over the seven days of self-filtration. A clogging layer was observed on the infiltration basin bottom, probably due to straining over the stormwater infiltration stage. Particle-size analyses also indicate that retention of bigger SP led to faster straining of smaller SP, despite the small fraction of bigger SP. The clogging layer weakened the hydraulic connection between the water level in the basin and the water table of the unconfined aquifer until nearly no water could infiltrate into the aquifer. The deposition of finer SP that entered into the aquifer are governed by the hydrodynamic forces. These finer SP caused non-uniform permeability reduction of the porous medium, with an estimated 35% of permeability reduction occurring beneath the infiltration basin. However, the reduction appears to be reversible, as the fine SP deposited on the pore surfaces of the porous medium can be released or detached by the continuous horizontal hydraulic gradient. Extended tailing of the outlet breakthrough curve (BTC) also strongly supported the detachment of SP. This study focused on the effects of particles’ polydispersity and hydrodynamic forces on the hydraulic characteristics of the porous medium. Full article
(This article belongs to the Section Water and Wastewater Treatment)
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