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Water, Volume 9, Issue 8 (August 2017)

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Open AccessArticle Is the Achievement of “Good Status” for German Surface Waters Disproportionately Expensive?—Comparing Two Approaches to Assess Disproportionately High Costs in the Context of the European Water Framework Directive
Water 2017, 9(8), 554; doi:10.3390/w9080554
Received: 20 June 2017 / Revised: 13 July 2017 / Accepted: 17 July 2017 / Published: 25 July 2017
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Abstract
Currently only 8.2% of German surface water bodies have reached the goal of the European Water Framework Directive to bring all water into a “good status”. For all water bodies that presumably will not achieve the objective by 2027, the member states have
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Currently only 8.2% of German surface water bodies have reached the goal of the European Water Framework Directive to bring all water into a “good status”. For all water bodies that presumably will not achieve the objective by 2027, the member states have to justify an exemption by 2021, for example, by arguing that the costs of achieving “good status“ would be “disproportionately high”. In this paper, two approaches for assessing cost-disproportionality of surface water bodies are empirically tested and compared on a set of real-world data from a German federal state. In the first approach, called average cost approach, costs are considered as being disproportionately high if they are significantly higher than what would be a “relatively normal effort”. The core idea of the second, the benchmark approach, is to take the past public expenditures on water management as a basis for comparison. Both approaches include generated utility for determination of a water-body-specific disproportionality threshold. While the benchmarking approach needs less data, the empirical tests indicate that both approaches yield comparable results and are suitable to support authorities in the decision as to which water bodies are to be considered disproportionately expensive such that exemptions are justified. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Comparing the Spectroscopic and Molecular Characteristics of Different Dissolved Organic Matter Fractions Isolated by Hydrophobic and Anionic Exchange Resins Using Fluorescence Spectroscopy and FT-ICR-MS
Water 2017, 9(8), 555; doi:10.3390/w9080555
Received: 13 June 2017 / Revised: 18 July 2017 / Accepted: 20 July 2017 / Published: 25 July 2017
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Abstract
Despite the environmental significance of dissolved organic matter (DOM), characterizing DOM is still challenging due to its structural complexity and heterogeneity. In this study, three different chemical fractions, including hydrophobic acid (HPOA), transphilic acid (TPIA), and hydrophilic neutral and base (HPIN/B) fractions, were
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Despite the environmental significance of dissolved organic matter (DOM), characterizing DOM is still challenging due to its structural complexity and heterogeneity. In this study, three different chemical fractions, including hydrophobic acid (HPOA), transphilic acid (TPIA), and hydrophilic neutral and base (HPIN/B) fractions, were separated from bulk aquatic DOM samples, and their spectral features and the chemical composition at the molecular level were compared using both fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The HPIN/B fraction was distinguished from the two acidic fractions (i.e., HPOA and TPIA) by the EEM-PARAFAC, while the TPIA fraction was discriminated by using the molecular parameters derived from the FT-ICR MS analyses. Statistical comparison suggests that the spectral dissimilarity among the three chemical fractions might result from the acido-basic properties of DOM samples, while the differences in molecular composition were more likely to be affected by the hydrophobicity of the DOM fractions. The non-metric multidimensional scaling map further revealed that the HPOA was the most heterogeneous among the three fractions. The number of overlapping formulas among the three chemical fractions constituted only <5% of all identified formulas, and those between two different fractions ranged from 2.0% to 24.1%, implying relatively homogeneous properties of the individual chemical fractions with respect to molecular composition. Although employing chemical fractionation achieved a lowering of the DOM heterogeneity, prevalent signatures of either acido-basic property or the hydrophobic nature of DOM on the characteristics of three chemical isolated fractions were not found for this study. Full article
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Open AccessArticle Relationship between Industrial Water Use and Economic Growth in China: Insights from an Environmental Kuznets Curve
Water 2017, 9(8), 556; doi:10.3390/w9080556
Received: 13 February 2017 / Revised: 20 July 2017 / Accepted: 21 July 2017 / Published: 25 July 2017
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Abstract
Global inequity and the unbalance of water resources has been a critical issue for many years; and the Chinese per capita water resources are only 1/4 of the global average. Meanwhile, as the Chinese economy is growing rapidly, the demand of Chinese industrial
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Global inequity and the unbalance of water resources has been a critical issue for many years; and the Chinese per capita water resources are only 1/4 of the global average. Meanwhile, as the Chinese economy is growing rapidly, the demand of Chinese industrial water use is also increasing. In this case, it is important to balance the relationship between economic growth and industrial water use. In this study, a reduction model is established for the northeastern, northern coastal, eastern coastal, southern coastal, middle Yellow River, middle Yangtze River, southwestern, and northwestern regions to verify the environmental Kuznets curve (EKC) for their respective industrial water use and provide theoretical support for decision making from an economic perspective. It adopts the per capita industrial water use and GDP of the eight economic zones from 2002 to 2014. The unit root test and co-integration test were adopted to analyze the stationarity of the data, and the triple reduction model was used for the fitting of variables. The relationship between per capita industrial water use and GDP showed an inverted U-shaped curve from 2002 to 2014 for China, as well as for the eastern coastal and middle Yangtze River regions, with the coordinates of the turning points being (9.8749, 4.6735), (10.3098, 5.4783), and (9.8184, 5.0622), respectively. The per capita GDP at the turning point of the inverted U-shaped curve is 18,000–30,000 Yuan (at constant prices from 2000). This study provides important thoughts and lessons for collaborative research into the relationship between industrial water consumption and economic development. The central government should focus on the central and western regions when creating policies for water resource management and technological development to improve their industrial water use efficiency. Full article
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Open AccessArticle Regional Correlation between Precipitation and Vegetation in the Huang-Huai-Hai River Basin, China
Water 2017, 9(8), 557; doi:10.3390/w9080557
Received: 16 June 2017 / Revised: 17 July 2017 / Accepted: 21 July 2017 / Published: 25 July 2017
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Abstract
In a context of climate change, precipitation patterns show substantial disturbances and the occurrence of precipitation anomalies has tended to increase in the Huang-Huai-Hai River Basin. These anomalies are likely influencing vegetation dynamics and ecosystem stability. This paper aims to have a comprehensive
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In a context of climate change, precipitation patterns show substantial disturbances and the occurrence of precipitation anomalies has tended to increase in the Huang-Huai-Hai River Basin. These anomalies are likely influencing vegetation dynamics and ecosystem stability. This paper aims to have a comprehensive understanding of vegetation growth response towards the precipitation pattern in the Huang-Huai-Hai River Basin. The study used NDVI (Normalized Difference Vegetation Index) data and mapped precipitation datasets from 1982 to 2011. NDVI and precipitation show a similar spatial distribution: they decrease from the southeast coast to the northwest inland. Regions with sparse vegetation are mainly distributed in arid and semi-arid areas or densely-populated areas. Vegetation coverage and the regular precipitation pattern show a positive correlation (61.6% of the whole region), while the correlation between vegetation coverage and precipitation anomalies is negative (62.7% for rainless days and 60.3% for rainstorm days). The clustering result shows that abundant vegetation is mainly situated in high precipitation or low anomaly areas. On the contrary, the degraded regions are mainly distributed in low precipitation or high anomaly areas. However, some special regions, mainly located in the Three North Shelterbelt Program region, the Tibetan Plateau, and other regions along the rivers, present improved vegetation cover when precipitation decreases or extreme events occur. Full article
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Open AccessArticle Spatial and Seasonal Surface Water Quality Assessment in a Tropical Urban Catchment: Burío River, Costa Rica
Water 2017, 9(8), 558; doi:10.3390/w9080558
Received: 9 June 2017 / Revised: 11 July 2017 / Accepted: 17 July 2017 / Published: 13 August 2017
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Abstract
Water quality assessments are essential for providing information regarding integrated water resource management processes. This study presents the results of a spatial and seasonal surface water quality assessment of the Burío river sub-catchment in Costa Rica. Fourteen sample campaigns were conducted at eight
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Water quality assessments are essential for providing information regarding integrated water resource management processes. This study presents the results of a spatial and seasonal surface water quality assessment of the Burío river sub-catchment in Costa Rica. Fourteen sample campaigns were conducted at eight sample sites between 2005 and 2010. Seasonal variations were evaluated using linear mixed-effects models where dissolved oxygen, total solids, and nitrate showed significant differences between dry and wet seasons (p < 0.05). Cluster analysis identified three clusters at the top, middle, and bottom of the catchment that were consistent with land use patterns, and principal component analysis identified the main parameters that were affecting 84% of the total variance in water quality (biochemical oxygen demand, dissolved oxygen, total phosphate, and nitrate). The National Sanitation Foundation Water Quality Index (NSF-WQI) results indicated the majority of the river consisted of mainly “medium” water quality, although “bad” and “good” water quality results were identified depending on sample site and season. This methodological approach provides a useful monitoring technique for local governments that can be used for further remediation strategies. Full article
(This article belongs to the Special Issue New Advances in Integrated River Basin Management)
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Open AccessFeature PaperArticle Accounting for the Assimilative Capacity of Water Systems in Scotland
Water 2017, 9(8), 559; doi:10.3390/w9080559
Received: 16 June 2017 / Revised: 13 July 2017 / Accepted: 21 July 2017 / Published: 26 July 2017
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Abstract
A key methodological challenge in understanding the relationship between the economy and the underlying ecosystem base resides in how to account for the ecosystem’s degradation and the decline of associated ecosystem services. In this study, we use information on nutrients and metals concentrations
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A key methodological challenge in understanding the relationship between the economy and the underlying ecosystem base resides in how to account for the ecosystem’s degradation and the decline of associated ecosystem services. In this study, we use information on nutrients and metals concentrations from the Environmental Change Network (ECN) database and the Scottish Environment Protection Agency (SEPA) for the period 2000–2010 in order to assess the assimilation capacity of water systems. The research covers five upstream sites and 17 downstream sites in northeast Scotland. Our results highlight the relevance of considering a number of pollutants, and suggest that elements such as arsenic, lead and mercury can pose a threat to ecosystems’ sustainability and health. However, little research has been done in terms of their assimilation capacity and their impact on grey water footprint assessments. In addition, the results indicate that background conditions might be relevant when performing sustainability analysis at different spatial scales. The study also poses relevant questions in relation to land management approaches versus traditional ‘end-of-pipe’ water treatment approaches, and the definition of maximum and background concentrations. In this regard, further studies will be required to understand the trade-offs between different ecosystem services depending on how these concentrations are defined. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessFeature PaperArticle Source Water Protection in Rural Newfoundland and Labrador: Limitations and Promising Actions
Water 2017, 9(8), 560; doi:10.3390/w9080560
Received: 9 May 2017 / Revised: 1 July 2017 / Accepted: 17 July 2017 / Published: 26 July 2017
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Abstract
The purpose of this paper is to exemplify through recent research in Newfoundland and Labrador (NL) the extent of the current limitations for source water protection and potential opportunities for improvement in the province, particularly for rural communities. The findings of this paper
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The purpose of this paper is to exemplify through recent research in Newfoundland and Labrador (NL) the extent of the current limitations for source water protection and potential opportunities for improvement in the province, particularly for rural communities. The findings of this paper draw from the results of four related studies led by the co-authors. These four studies took place in NL between 2012 and 2016, and derived data through a mixed-method approach using literature reviews, key informant interviews, surveys, and consultations. The article provides an overview of the state of source water protection in NL and the challenges faced, with case examples to illustrate key points. Findings indicate there is currently a source water protection gap in NL limiting local governments in implementing their source water protection obligations under provincial policy and regulations. This implementation gap has been attributed to a lack of capacity for watershed monitoring, a lack of awareness of the need for source water protection and of municipal responsibilities, conflicts over multi-use watersheds and a lack of watershed planning and management. Greater education and collaboration in source water protection efforts amongst all watershed users, watershed groups, local governments and the provincial government could offer promise to fill this gap. Full article
(This article belongs to the Special Issue Source Water Protection: State of the Art and Science)
Open AccessArticle Hydrological Design of Two Low-Impact Development Techniques in a Semi-Arid Climate Zone of Central Mexico
Water 2017, 9(8), 561; doi:10.3390/w9080561
Received: 25 June 2017 / Revised: 20 July 2017 / Accepted: 21 July 2017 / Published: 26 July 2017
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Abstract
This paper deals with the design of a bioretention cell and an infiltration trench in a semi- arid micro watershed. The study area was analyzed by characteristics such as slope changes (S), direction and maximum length of the urban runoff (
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This paper deals with the design of a bioretention cell and an infiltration trench in a semi- arid micro watershed. The study area was analyzed by characteristics such as slope changes (S), direction and maximum length of the urban runoff (L), and soil use (runoff coefficient, Rc). The bioretention cell was designed by the calculation of variables such as drainage area (A), concentration time (Tc), rainfall intensity (i), maximum peak drained (Qmax), inlet and outlet runoff (Qa and Qout, respectively), temperature (T), evaporation (Ev), potential evapotranspiration (PEm), consumptive use (U) for tolerant plants to semi-arid climates, and soil infiltration capacity (Inf). To design the infiltration trench, only Tc, Qmax, and i were taken into account. The results showed that the designed bioretention cell could retain between 5.37% and 2.25% of runoff volume. As the efficiency of the bioretention cell can be defined by the need for additional irrigation, our results showed that the cell is inefficient in some of the dry months (November and December), even in years characterized by abundant rainfall. Besides, it was shown that the designed infiltration trench could store or infiltrate the water from typical rain events. Based on these results, it is the implementation of more Low-Impact Development (LID) for runoff management in the study area is recommended. Full article
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Open AccessArticle Ecological and Public Health Implications of the Discharge of Multidrug-Resistant Bacteria and Physicochemical Contaminants from Treated Wastewater Effluents in the Eastern Cape, South Africa
Water 2017, 9(8), 562; doi:10.3390/w9080562
Received: 23 March 2017 / Revised: 22 July 2017 / Accepted: 23 July 2017 / Published: 1 August 2017
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Abstract
This study assessed the prevalence of fecal indicator bacteria (FIB) and Vibrio species, as well as the physicochemical qualities of the discharged effluents of two wastewater treatment facilities, in the Eastern Cape, South Africa over a one-year sampling period using standard methods. Bacteriological
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This study assessed the prevalence of fecal indicator bacteria (FIB) and Vibrio species, as well as the physicochemical qualities of the discharged effluents of two wastewater treatment facilities, in the Eastern Cape, South Africa over a one-year sampling period using standard methods. Bacteriological assessment revealed presumptive E. coli counts ranging from 3 to 1.2 × 105 CFU/100 mL, while counts of Vibrio spp. ranged from 11 to 1.4 × 104 CFU/100 mL. Molecular identification of the isolates by polymerase chain reactions (PCR) yielded positive reaction rates of 76.2% (381/500) and 69.8% (279/400) for E. coli and Vibrio species, respectively. The antibiotic susceptibility profiles of 205 randomly selected PCR-confirmed Vibrio isolates against 18 antibiotics revealed resistance frequencies ranging from 0.5% (imipenem) to 96.1% (penicillin G), based on recommended breakpoint concentrations. About 81% (166/205) of the Vibrio isolates exhibited multidrug resistance (resistance to three or more classes of antibiotics), while nine different antibiotic resistance genes were detected by PCR. The physicochemical qualities of the effluents also ranged as follows: pH (6.5–7.6), temperature (12–27 °C), turbidity (1.5–65.7 mg/L), total dissolved solids (95–171 mg/L), dissolved oxygen (2.1–9.8), electrical conductivity (134–267 µS/cm), free chlorine (0.08–0.72 mg/L), biochemical oxygen demand (0.12–9.81 mg/L), nitrate (1.04–21.5 mg/L), nitrite (0.11–0.76 mg/L), phosphate (1.03–18.3 mg/L) and chemical oxygen demand (27–680 mg/L). The discharged effluents fell short of the regulatory guidelines for some of the parameters assessed. We conclude that the discharged effluents are potential sources of environmental pollution and can contribute to drug resistant bacteria load in the receiving watershed, with the associated ecological and human health risks. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Open AccessArticle Study on Effects of Electron Donors on Phosphine Production from Anaerobic Activated Sludge
Water 2017, 9(8), 563; doi:10.3390/w9080563
Received: 12 June 2017 / Revised: 13 July 2017 / Accepted: 24 July 2017 / Published: 30 July 2017
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Abstract
The effects of different types and concentrations of electron donors (glucose, starch, methanol and sodium acetate) on the formation of phosphine from anaerobic activated sludge that has been domesticated for a prolonged period were studied in small batch experiments. The results show that
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The effects of different types and concentrations of electron donors (glucose, starch, methanol and sodium acetate) on the formation of phosphine from anaerobic activated sludge that has been domesticated for a prolonged period were studied in small batch experiments. The results show that types and concentrations of electron donor have significant effects on the production of phosphine from anaerobic activated sludge. Among them, glucose was the most favourable electron donor, whereas sodium acetate was the least favourable electron donor for the removal of phosphorus and the production of phosphine. Higher concentrations of electron donors were more favourable for the reduction of phosphate into phosphine, and supplying more than nine times the amount of electron donor as theoretically required for the reduction of phosphate into phosphine was favourable for the production of phosphine. Full article
(This article belongs to the Special Issue Biological Treatment of Wastewater)
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Open AccessFeature PaperArticle Modelling Fine Sediment Dynamics: Towards a Common Erosion Law for Fine Sand, Mud and Mixtures
Water 2017, 9(8), 564; doi:10.3390/w9080564
Received: 7 June 2017 / Revised: 17 July 2017 / Accepted: 18 July 2017 / Published: 27 July 2017
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Abstract
This study describes the building of a common erosion law for fine sand and mud, mixed or not, in the case of a typical continental shelf environment, the Bay of Biscay shelf, characterized by slightly energetic conditions and a seabed mainly composed of
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This study describes the building of a common erosion law for fine sand and mud, mixed or not, in the case of a typical continental shelf environment, the Bay of Biscay shelf, characterized by slightly energetic conditions and a seabed mainly composed of fine sand and muddy sediments. A 3D realistic hydro-sedimentary model was used to assess the influence of the erosion law setting on sediment dynamics (turbidity, seabed evolution). A pure sand erosion law was applied when the mud fraction in the surficial sediment was lower than a first critical value, and a pure mud erosion law above a second critical value. Both sand and mud erosion laws are formulated similarly, with different parameters (erodibility parameter, critical shear stress and power of the excess shear stress). Several transition trends (linear or exponential) describing variations in these erosion-related parameters between the two critical mud fractions were tested. Suspended sediment concentrations obtained from simulations were compared to measurements taken on the Bay of Biscay shelf with an acoustic profiler over the entire water column. On the one hand, results show that defining an abrupt exponential transition improves model results regarding measurements. On the other hand, they underline the need to define a first critical mud fraction of 10 to 20%, corresponding to a critical clay content of 3–6%, below which pure sand erosion should be prescribed. Both conclusions agree with results of experimental studies reported in the literature mentioning a drastic change in erosion mode above a critical clay content of 2–10% in the mixture. Results also provide evidence for the importance of considering advection in this kind of validation with in situ observations, which is likely to considerably influence both water column and seabed sediment dynamics. Full article
(This article belongs to the Special Issue Sediment Transport in Coastal Waters)
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Open AccessArticle Numerical Simulation of Hydrodynamics and Reaeration over a Stepped Spillway by the SPH Method
Water 2017, 9(8), 565; doi:10.3390/w9080565
Received: 29 June 2017 / Revised: 18 July 2017 / Accepted: 20 July 2017 / Published: 27 July 2017
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Abstract
Aerated flows are characterized by complex hydrodynamics and mass-transfer processes. As a Lagrangian method, smoothed particle hydrodynamics (SPH) has a significant advantage in tracking the air-water interface in turbulent flows. This paper presents the application of an SPH method to investigate hydrodynamics and
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Aerated flows are characterized by complex hydrodynamics and mass-transfer processes. As a Lagrangian method, smoothed particle hydrodynamics (SPH) has a significant advantage in tracking the air-water interface in turbulent flows. This paper presents the application of an SPH method to investigate hydrodynamics and reaeration over stepped spillways. In the SPH method, the entrainment of dissolved oxygen (DO) is studied using a multiphase mass transfer SPH method for reaeration. The numerical results are compared with the hydrodynamics data from Chanson and DO data from Cheng. The simulation results show that velocity distribution and the location of free-surface aeration inception agree with the experimental results. Compared with the experimental results, the distribution of DO concentration over the stepped spillway is consistent with the measurement results. The study shows that the two-phase DO mass transfer SPH model is reliable and reasonable for simulating the hydrodynamics characteristics and reaeration process. Full article
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Open AccessArticle Simulating the Effects of Lake Wind Waves on Water and Solute Exchange across the Lakeshore Using Hydrus-2D
Water 2017, 9(8), 566; doi:10.3390/w9080566
Received: 28 March 2017 / Revised: 23 July 2017 / Accepted: 26 July 2017 / Published: 30 July 2017
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Abstract
Wind waves, which frequently occur on large surface water bodies such as lakes, may temporarily alter flow patterns in a subsurface zone and the corresponding water and nutrient interactions between surface waters and shallow groundwaters. To better understand these processes, soil flume experiments
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Wind waves, which frequently occur on large surface water bodies such as lakes, may temporarily alter flow patterns in a subsurface zone and the corresponding water and nutrient interactions between surface waters and shallow groundwaters. To better understand these processes, soil flume experiments were carried out to investigate wind wave-driven water and chloride interactions across the lake–groundwater interface, and the Hydrus-2D model was used to analyze and evaluate the observed experimental results. Two interaction cases between the lake and groundwater systems were considered: groundwater discharging into a lake (the GDL case), and lake water recharging groundwater (the LRG case). For comparison, no-wave conditions for both the GDL and LRG cases were also analyzed. The results revealed that, similarly to no-wave conditions, water and chloride exchange fluxes between the lake and groundwater systems under wave conditions occurred mainly within narrow bands near the intersection of the water level in the lake and the interface in both the GDL and LRG cases, and then exponentially decreased along the interface. Most water and chloride that infiltrated into the subsurface zone through the upper part of the interface during a wave crest returned to the lake through the lower part during a wave trough in both the GDL and LRG cases, creating local recirculation zones in the subsurface near the interface. Such recirculation produced a more frequent exchange of water and solute across the interface compared with those under no-wave conditions. During a one-day period after wind waves started, the total exchange fluxes of water and chloride to the lake decreased by 36.2% and 71.9%, respectively, compared to the no-wave conditions in the GDL case. In the LRG case, the total exchange water fluxes to the subsurface increased by 89.7%, while the total exchange chloride fluxes increased only slightly (4.5%) compared to the no-wave conditions due to the difference in chloride concentrations between the upper and lower parts of the interface. The sensitivity analysis revealed that the hydraulic conductivity of the lakeshore zone and the characteristics of the waves were important factors influencing water and chloride exchange between the lake and groundwater systems. The simulated results helped us to better understand water and solute interactions in the lake–groundwater system during windy periods. Full article
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Open AccessArticle Comparison of SWAT and GWLF Model Simulation Performance in Humid South and Semi-Arid North of China
Water 2017, 9(8), 567; doi:10.3390/w9080567
Received: 31 May 2017 / Revised: 19 July 2017 / Accepted: 27 July 2017 / Published: 30 July 2017
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Abstract
Watershed models have gradually been adapted to support both decision and policy making for global environmental pollution control. In this study, two watershed models with different complexity, the Soil and Water Assessment Tool (SWAT) and the Generalized Watershed Loading Function (GWLF), were applied
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Watershed models have gradually been adapted to support both decision and policy making for global environmental pollution control. In this study, two watershed models with different complexity, the Soil and Water Assessment Tool (SWAT) and the Generalized Watershed Loading Function (GWLF), were applied in two catchments in data scarce China, namely the Tunxi and the Hanjiaying basins with contrasting climatic conditions (humid and semi-arid, respectively). The performances of both models were assessed via comparison between simulated and measured monthly streamflow, sediment yield, and total nitrogen. Time series plots as well as four statistical measures (the coefficient of determination (R2), the Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS), and RMSE (root mean square error)—observations standard deviation ratio (RSR)) were used to estimate the performance of both models. The results show that both models were generally able to simulate monthly streamflow, sediment, and total nitrogen loadings during the simulation period. However, SWAT performed better for detailed representations, while GWLF could produce much better average values of the observed data. Thus, GWLF offers a user-friendly prospective alternative watershed model that requires little input data and that is applicable for areas where the input data required for SWAT are not always available. SWAT is more suitable for projects that require high accuracy and offers an advantage when measured data are scarce. Full article
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Open AccessArticle Optimal Hedging Rules for Water Supply Reservoir Operations under Forecast Uncertainty and Conditional Value-at-Risk Criterion
Water 2017, 9(8), 568; doi:10.3390/w9080568
Received: 1 May 2017 / Revised: 4 July 2017 / Accepted: 26 July 2017 / Published: 30 July 2017
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Abstract
Hedging rules for water supply reservoir operations provide guidelines for balancing the consequences of competing water allocations. When inflow forecast uncertainty is addressed, hedging acts as insurances for offsetting the negative influence of water shortage in the future, especially when drought is anticipated.
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Hedging rules for water supply reservoir operations provide guidelines for balancing the consequences of competing water allocations. When inflow forecast uncertainty is addressed, hedging acts as insurances for offsetting the negative influence of water shortage in the future, especially when drought is anticipated. This study used a risk-averse criterion, the conditional value-at-risk (CVaR), rather than the expected value (EV) criterion, to rationalize water delivery for overcoming the shortcomings of risk-neutral hedging rules in minimizing water shortage impacts in unfavorable realizations, in which actual inflow is less than anticipated. A two-period hedging model with the objective of maximizing the CVaR of total benefits from water delivery and water storage is established, and the optimal hedging rules using first-order optimality condition are analytically derived. Differences in hedging rules under the two criteria are highlighted by theoretical analysis and numerical experiments. The methods are applied to guide the operations of a water supply reservoir, and results show that: (1) the hedging rules under the EV criterion are special cases under the CVaR criterion; (2) water delivery in the current period would be greatly curtailed under the high influence of forecast uncertainty or the significant risk-averse attitude of decision makers; (3) hedging to maximize the CVaR of total benefit is at the cost of reducing the EV of total benefit; and (4) in real-time operations, compared with the hedging policies under the EV criterion, the hedging policies under the CVaR criterion would be more effective when applied to dry and extremely dry hydrological conditions, especially when inflow is overestimated. These implications provide new insights into rationing water supply and risk aversion. Full article
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Open AccessArticle Identifying Groundwater Recharge Sites through Environmental Stable Isotopes in an Alluvial Aquifer
Water 2017, 9(8), 569; doi:10.3390/w9080569
Received: 26 June 2017 / Revised: 26 July 2017 / Accepted: 28 July 2017 / Published: 2 August 2017
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Abstract
Environmental isotope tracers have been a useful tool in providing new insights into hydrologic processes. In Mexico, there have been several studies reporting different values for δ18O and δ2H for certain geographical areas. The objective of this study is
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Environmental isotope tracers have been a useful tool in providing new insights into hydrologic processes. In Mexico, there have been several studies reporting different values for δ 18 O and δ 2 H for certain geographical areas. The objective of this study is to achieve the isotopic characterization of rainfall and groundwater and to report the comprehensive understanding of groundwater flow processes around and within the Calera aquifer and, consequently, its potential recharge sites. The samples used for the stable isotope analysis ( δ 18 O , δ 2 H ) were measured using a GV-Isoprime isotope-ratio mass spectrometer at the Isotopy Laboratory of the Water Center for Latin America and the Caribbean. The δ D of precipitation ranged between −110.20‰ and 10.11‰, with a mean of −55.67‰ ± 27.81‰. The δ 18 O ranged between −17.80‰ and 2.74‰, with a mean of −9.44‰ ± 4.74‰. The δ D of groundwater ranged between −81.92‰ and −36.45‰, with a mean of −66.05‰ ± 8.58‰. The δ 18 O ranged between −18.26‰ and −8.84‰, with a mean of −12.35‰ ± 2.12‰. The local meteoric water line of the Zacatecas state is δ D = 2.03 + 5.68 δ 18 O . The groundwater samples were clustered into four groups. The clustering of the samples led to the finding that streamflows play a significant role in the hydrological balance as a source of local recharge to the aquifer. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Spatiotemporal Variation of Turbidity Based on Landsat 8 OLI in Cam Ranh Bay and Thuy Trieu Lagoon, Vietnam
Water 2017, 9(8), 570; doi:10.3390/w9080570
Received: 12 April 2017 / Revised: 31 May 2017 / Accepted: 15 June 2017 / Published: 8 August 2017
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Abstract
In recent years, seagrass beds in Cam Ranh Bay and Thuy Trieu Lagoon have declined from 800 to 550 hectares, resulting insignificantly reducing the number of fish catch. This phenomenon is due to the effect of the degradation of water environment. Turbidity is
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In recent years, seagrass beds in Cam Ranh Bay and Thuy Trieu Lagoon have declined from 800 to 550 hectares, resulting insignificantly reducing the number of fish catch. This phenomenon is due to the effect of the degradation of water environment. Turbidity is one of the most important water quality parameters directly related to underwater light penetration which affects the primary productivity. This study aims to investigate spatiotemporal variation of turbidity in the waters with major factors affecting its patterns using remote sensing data. An algorithm for turbidity retrieval was developed based on the correlation between in situ measurements and a red band of Landsat 8 OLI with R2 = 0.84 (p < 0.05). Simulating WAves Nearshore (SWAN) model was used to compute bed shear stress, a major factor affecting turbidity in shallow waters. In addition, the relationships between turbidity and rainfall, and bed shear stress induced by wind were analyzed. It was found that: (1) In the dry season, turbidity was low at the middle of the bay while it was high in shallow waters nearby coastlines. Resuspension of bed sediment was a major factor controlling turbidity during time with no rainfall. (2) In the rainy season or for a short time after rainfall in the dry season, turbidity was high due to a large amount of runoff entering into the study area. Full article
(This article belongs to the Special Issue Sediment Transport in Coastal Waters)
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Open AccessArticle Valuation of Hidden Water Ecosystem Services: The Replacement Cost of the Aquifer System in Central Mexico
Water 2017, 9(8), 571; doi:10.3390/w9080571
Received: 29 April 2017 / Revised: 7 July 2017 / Accepted: 21 July 2017 / Published: 31 July 2017
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Abstract
This paper reports research estimating the costs of replacing the groundwater that the metropolitan areas of Mexico City, Toluca, and Cuernavaca, in Central Mexico, pump from 10 over-exploited aquifers with 6 supply alternatives of surface water. These aquifers provide about 70% of the
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This paper reports research estimating the costs of replacing the groundwater that the metropolitan areas of Mexico City, Toluca, and Cuernavaca, in Central Mexico, pump from 10 over-exploited aquifers with 6 supply alternatives of surface water. These aquifers provide about 70% of the water required by more than 28 million people, and their recharge zones in forested areas are increasingly threatened by economic activities. By designing a constrained optimization program that minimizes investment and operation costs, we found that replacing groundwater extraction involves the construction of all six alternatives at an estimated cost of US$25 billion at present values (US$0.6 m−3 over a 26-year period). We designed and analyzed a scenario to combine measures to reduce water leaks in Mexico City; a positive balance was found: every dollar invested in leak control reduces replacement costs by between US$1.9 and US$8.4. Therefore, our results suggest the prioritization of leak control measures in order to reduce extraction from over-exploited aquifers. Local authorities should be warned about the economics of losing ecosystem services that are crucial to sustaining the population and the economic activities in the region of study. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Derivation of Flow Duration Curves to Estimate Hydropower Generation Potential in Data-Scarce Regions
Water 2017, 9(8), 572; doi:10.3390/w9080572
Received: 6 July 2017 / Revised: 24 July 2017 / Accepted: 26 July 2017 / Published: 31 July 2017
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Abstract
Small-scale hydropower is a robust and reliable form of sustainable energy supply in remote areas. On the one hand, the potential for hydropower generation depends on the specific climate in a given place, and precipitation above all. On the other hand, such potential
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Small-scale hydropower is a robust and reliable form of sustainable energy supply in remote areas. On the one hand, the potential for hydropower generation depends on the specific climate in a given place, and precipitation above all. On the other hand, such potential also depends on the catchment’s characteristics, e.g., topography, land use, and soils. In the absence of discharge measurements, the available river flow for hydropower production can be estimated in the form of a flow duration curve based on these variables. In this study, the lumped rainfall-runoff method by Crawford and Thurin (1981) was modified to calculate a flow duration curve with a daily time step for an ungauged catchment in Nicaragua. Satisfactory results could be obtained by calibrating the method with the aid of a few discharge measurements. Best results were obtained with a parameter set for groundwater flow and recharge to groundwater from excess soil moisture of 0.014 and 0.6, respectively. Considering the climate and catchment characteristics of the study site, this parameterization can be physically reasoned. Full article
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Open AccessArticle An Optimization Model for Waste Load Allocation under Water Carrying Capacity Improvement Management, A Case Study of the Yitong River, Northeast China
Water 2017, 9(8), 573; doi:10.3390/w9080573
Received: 27 June 2017 / Revised: 27 July 2017 / Accepted: 27 July 2017 / Published: 1 August 2017
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Abstract
In this study, a two-stage stochastic programming (TSP) model was developed for supporting regional waste load(chemical oxygen demand (COD)and NH3-N) allocation in four main pollution departments (industry, municipal, livestock breeding, and agriculture), constrained by the water carrying capacity, which can be
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In this study, a two-stage stochastic programming (TSP) model was developed for supporting regional waste load(chemical oxygen demand (COD)and NH3-N) allocation in four main pollution departments (industry, municipal, livestock breeding, and agriculture), constrained by the water carrying capacity, which can be improved by ecological restoration engineering, in the nine function zones of the Yitong River. A number of scenarios corresponding to different stream flow levels were examined. The results revealed that the carrying capacity of COD and NH3-N has a similar tendency with a positive correlation to stream flow levels. The allocation amount of each pollutant for the four departments was obtained differently in each zone, and ecological restoration engineering solutions were obtained for different zones to improve the carrying capacity of the pollutants in order to meet the permitted emission allocation and water qualities. The results are helpful in establishing a rational discharge permit system of each pollution unit under water quality targets, and provide a basis for production plans of these pollution units. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Temporal and Spatial Variations of Hydrological Processes on the Landscape Zone Scale in an Alpine Cold Region (Mafengou River Basin, China): An Update
Water 2017, 9(8), 574; doi:10.3390/w9080574
Received: 7 June 2017 / Revised: 25 July 2017 / Accepted: 26 July 2017 / Published: 12 August 2017
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Abstract
This study investigates precipitation, snow, groundwater, glaciers and frozen soil in different landscape zones using isotopic and hydrogeochemical tracers. The aim of this study is to identify temporal and spatial variations, as well as hydrological processes in the alpine cold region. The results
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This study investigates precipitation, snow, groundwater, glaciers and frozen soil in different landscape zones using isotopic and hydrogeochemical tracers. The aim of this study is to identify temporal and spatial variations, as well as hydrological processes in the alpine cold region. The results show that there was no significant difference in water chemical characteristics of various waterbodies, and no obvious temporal variation, but exhibited spatial variation. In the wet season, various waterbodies are enriched in oxygen δ18O and deuterium δD due to a temperature effect. Precipitation and the temperature decrease during the dry season, which cannot easily be affected by secondary evaporation. The d-excess (deuterium excess) of various waterbodies was greater than 10‰. There are no altitude effects during wet and dry seasons because the recharged water resources are different in the wet and dry seasons. It is influenced by the freezing-thawing process of glacier snow and frozen soil. The river water is recharged by thawed frozen soil water and precipitation in the wet season, but glacier snow meltwater with negative δ18O and δD is less (14–18%). In the dry season, glacier snow meltwater and groundwater are the dominant source of the river water, and thawed frozen soil water is less (10–15%). Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle A Method of Evaluating Water Resource Assets and Liabilities: A Case Study of Jinan City, Shandong Province
Water 2017, 9(8), 575; doi:10.3390/w9080575
Received: 18 June 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 1 August 2017
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Abstract
The traditional concepts of water resource development and utilization have caused serious hydrological and environmental issues in some regions. In addition, policy issues in China have led to a severe water crisis. The quantitative accounting of water resources is a theoretical approach to
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The traditional concepts of water resource development and utilization have caused serious hydrological and environmental issues in some regions. In addition, policy issues in China have led to a severe water crisis. The quantitative accounting of water resources is a theoretical approach to solving these problems. In this paper, 13 indicators were selected from four classes, including resources, the environment, society, and efficiency, and a case study of Jinan, Shandong Province, was performed using a set pair analysis model to calculate the water resource assets from 2011–2015. In previous methods of water resource accounting, the water quality was not considered; therefore, the loss coefficient of water resource assets was proposed to improve the reliability of accounting. According to the relationships among the unit price of water, water quantity, and water quality, physical and quantitative accounting methods were used to create water balance sheets from 2011–2015. The calculation results showed that the physical change in water resource assets in Jinan City was −30 million m 3 , and water resource assets initially increased and then decreased. In 2011, 2012, 2013, 2014, and 2015, water resource assets totalled 36.5 million USD, 45.9 million USD, 66.7 million USD, 35.5 million USD, and 37.5 million USD, respectively (at 6.4588, 6.3125, 6.1932, 6.2166, 6.2284 USRMB, respectively). This initial accounting provides quantitative and physical support for the improved management of water resources. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Carbon Dioxide Reduction Targets of Hot Water Showers for People in Hong Kong
Water 2017, 9(8), 576; doi:10.3390/w9080576
Received: 19 June 2017 / Revised: 24 July 2017 / Accepted: 31 July 2017 / Published: 2 August 2017
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Abstract
Improving water and energy efficiency in buildings is one of the best ways to reduce greenhouse gas emissions. This study examines various energy-related carbon dioxide (CO2) reduction measures, including the use of water efficient showerheads and shower drain water heat recovery,
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Improving water and energy efficiency in buildings is one of the best ways to reduce greenhouse gas emissions. This study examines various energy-related carbon dioxide (CO2) reduction measures, including the use of water efficient showerheads and shower drain water heat recovery, in order to distinguish the significance of user influence on the water usage of a shower. The probability of taking a hot shower and the number of showers taken by an occupant per day, which can be evaluated from open literature data, are used as the parameters of user responses to water conservation measures in this study. A Monte Carlo model of water consumption and CO2 reduction for showering is adopted to determine the contributions of user responses. The results demonstrate that the influence of users on CO2 reduction is significant and compatible to the influence of water efficient showerheads. This study can be used as a reference to enhance water and energy incentives and to facilitate continuous improvement in building water systems. Full article
(This article belongs to the Special Issue Water Supply and Drainage for Sustainable Built Environment)
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Open AccessFeature PaperArticle Effectiveness of ABC Waters Design Features for Runoff Quantity Control in Urban Singapore
Water 2017, 9(8), 577; doi:10.3390/w9080577
Received: 6 June 2017 / Revised: 7 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
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Abstract
Active, Beautiful, Clean Waters (ABC Waters) design features—natural systems consisting of plants and soil that detain and treat rainwater runoff—comprise a major part of Sustainable urban Drainage Systems (SuDS) in Singapore. Although it is generally accepted that ABC Waters design features are able
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Active, Beautiful, Clean Waters (ABC Waters) design features—natural systems consisting of plants and soil that detain and treat rainwater runoff—comprise a major part of Sustainable urban Drainage Systems (SuDS) in Singapore. Although it is generally accepted that ABC Waters design features are able to detain runoff and reduce peak flow, their effectiveness in doing so has not been studied or documented locally. This research aims to determine their effectiveness in reducing peak flow based on a newly constructed pilot precinct named Waterway Ridges. Four types of ABC Waters features have been integrated holistically within the development, and designed innovatively to allow the precinct to achieve an effective C-value of 0.55 for the 10-year design storm; the precinct-wide integration and implemented design with the aim of substantially reducing peak flow are firsts in Singapore. The study is based on results from an uncalibrated 1D hydraulic model developed using the Storm Water Management Model (SWMM). Identification of key design elements and performance enhancement of the features via optimisation were also studied. Results show that the features are effective in reducing peak flow for the 10-year design storm, by 33%, and allowed the precinct to achieve an effective C-value of 0.60. Full article
(This article belongs to the Special Issue Sponge Cities: Emerging Approaches, Challenges and Opportunities)
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Open AccessArticle Design, Construction, and Application of an Inexpensive, High-Resolution Water Sampler
Water 2017, 9(8), 578; doi:10.3390/w9080578
Received: 11 July 2017 / Revised: 31 July 2017 / Accepted: 1 August 2017 / Published: 3 August 2017
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Abstract
The cost of high-resolution water sampling devices for ecological studies and water quality analyses can be prohibitive. Moreover, the potential for operator error in the use of complicated sampling equipment can lead to inaccuracies. Here we describe the construction and operation of an
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The cost of high-resolution water sampling devices for ecological studies and water quality analyses can be prohibitive. Moreover, the potential for operator error in the use of complicated sampling equipment can lead to inaccuracies. Here we describe the construction and operation of an inexpensive and easy-to-use water sampler that achieves a water column sampling resolution of approximately 1 cm. The device is driven by a peristaltic pump and is constructed entirely of non-corrosive and non-reactive materials. The sampler has no moving parts and was completely reliable in fieldwork on temperate and Antarctic lakes. The device is especially suited for the collection of water samples from calm or stagnant surface waters, such as lakes, ponds, reservoirs, and deep swamps or other wetlands. In addition, because its components are unaffected by corrosive salts and sulfides, the device is suitable for sampling calm inlet waters, including shallow bays and estuaries. Because of its low cost, simple construction, compact design, and precision performance, this water sampler is an excellent option for studying and monitoring shallow to moderately deep (<50 m) natural waters. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle Assessment of the Impact of Climate Change on Drought Characteristics in the Hwanghae Plain, North Korea Using Time Series SPI and SPEI: 1981–2100
Water 2017, 9(8), 579; doi:10.3390/w9080579
Received: 28 April 2017 / Revised: 8 June 2017 / Accepted: 1 August 2017 / Published: 3 August 2017
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Abstract
North Korea is a food-deficit nation in which climate change could have a significant impact on drought. We analyzed drought characteristics in the Hwanghae Plain, North Korea using both the multiple timescales of the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration
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North Korea is a food-deficit nation in which climate change could have a significant impact on drought. We analyzed drought characteristics in the Hwanghae Plain, North Korea using both the multiple timescales of the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) from 1981 to 2100. The probability of non-exceedance for a one-month SPEI below −1.0 was only 1.1% in the spring season of 1995 but increased to 24.4% in 2085. The SPEI for a ten-year return period varied from −0.6 to −0.9 in 1995 and decreased to −1.18 in 2025. The results indicate that severe drought is more likely to occur in future as a result of climate change. The seasonal drought conditions were also significantly influenced by climate change. The largest decrease in the SPEI occurred in late spring and early summer, both of which are important for rice growth. Drought characteristics include severity, duration, and intensity. Therefore, we applied the time series of SPIs and SPEIs to the runs theory and found that the drought intensity identified by one-month SPEIs in 1995 was at a level of 1.21, which reached 1.39 in 2085, implying that climate change will intensify drought in the future. Full article
(This article belongs to the Special Issue Adaptation Strategies to Climate Change Impacts on Water Resources)
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Open AccessFeature PaperArticle Impact of Powdered Activated Carbon Structural Properties on Removal of Organic Foulants in Combined Adsorption-Ultrafiltration
Water 2017, 9(8), 580; doi:10.3390/w9080580
Received: 28 April 2017 / Revised: 28 June 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
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Abstract
The impact of structural properties of three commercial PACs as well as two mechanically ground PACs on their efficiency in NOM removal and fouling reduction in combined adsorption-ultrafiltration (PAC-UF) of northern German groundwater was investigated. All PACs showed highest adsorption affinity for medium
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The impact of structural properties of three commercial PACs as well as two mechanically ground PACs on their efficiency in NOM removal and fouling reduction in combined adsorption-ultrafiltration (PAC-UF) of northern German groundwater was investigated. All PACs showed highest adsorption affinity for medium molecular weight NOM fractions. The meso-pore surface area rather than the total surface area (B.E.T.) mainly governed the extent of NOM removal. However, adsorption of macromolecular NOM fractions, which were found to be the main contributor to total and irreversible fouling, was limited by tested commercial carbons, and no significant mitigation of fouling was achieved by any tested PAC concentration. Lowering the particle size by grinding of the PAC, however, enhanced removal of macromolecular NOM fractions considerably, and fouling mitigation occurred at substantially lower PAC concentrations compared to raw carbons. A larger external surface area probably let to more shell adsorption, a more homogeneous particle distribution on the membrane surface and a better mass transport. In addition, comparison of the adsorption isotherms of raw and milled PACs showed that, due to the grinding of PAC particles, additional inner pores structures became available for NOM adsorption. Results of this study point out that structural properties of PAC dramatically influence the efficiency of combined PAC-UF, which needs to be considered during PAC selection and process design. Full article
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Open AccessFeature PaperArticle Characterization and Treatment Proposals of Shipboard Slop Wastewater Contaminated by Hydrocarbons
Water 2017, 9(8), 581; doi:10.3390/w9080581
Received: 31 March 2017 / Revised: 19 June 2017 / Accepted: 30 July 2017 / Published: 4 August 2017
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Abstract
Shipboard slop wastewaters are produced by the activity of washing of oil tankers with seawater, and are characterized by high salinity and hydrocarbons. In this context, harbor authorities are forced to respect the international regulation IMO-MARPOL 73/78 and they must treat slop wastewater
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Shipboard slop wastewaters are produced by the activity of washing of oil tankers with seawater, and are characterized by high salinity and hydrocarbons. In this context, harbor authorities are forced to respect the international regulation IMO-MARPOL 73/78 and they must treat slop wastewater before discharging to the sea. This study compared data from three stand-alone treatments working with the same real slop wastewater: (1) a chemical treatment of coagulation-flocculation with aluminum sulphate as coagulant and an anionic flocculant (A57), (2) a physical treatment of adsorption on granular activated carbon (GAC), (3) two biological treatments represented by a membrane bioreactor (MBR) and a moving bed biofilm reactor (MB-MBR). GAC treatment registered the highest removal efficiency of total petroleum hydrocarbons (ηTPH) next to 85%, since the activated carbon had excellent adsorption properties towards organic substances. The coagulation-flocculation treatment reported the lowest ηTPH ≈ 57% due to the presence of emulsified hydrocarbons that were not affected by the coagulant and flocculant action, so remaining in liquid phase. ηTPH ≈ 70% obtained with MB-MBR fed with 100% volume of slop, suggested biomass acclimation to salinity and hydrocarbons. Based on the results of each process, three main treatment chains are proposed depending on the hydrocarbons load of the real slop wastewater. Full article
(This article belongs to the Special Issue Oily Water Treatment)
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Open AccessArticle Effect of Membrane Type for the Treatment of Organized Industrial Zone (OIZ) Wastewater with a Membrane Bioreactor (MBR): Batch Experiments
Water 2017, 9(8), 582; doi:10.3390/w9080582
Received: 11 July 2017 / Revised: 28 July 2017 / Accepted: 1 August 2017 / Published: 4 August 2017
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Abstract
Organized industrial zone (OIZ) wastewater is a mixed wastewater that is contributed by both municipal use and from different industrial sectors. Since MBR has advantages over conventional treatment plants, membrane types and fouling become the most important parameters in the treatment of this
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Organized industrial zone (OIZ) wastewater is a mixed wastewater that is contributed by both municipal use and from different industrial sectors. Since MBR has advantages over conventional treatment plants, membrane types and fouling become the most important parameters in the treatment of this kind of wastewater. In this study, six different membrane types were used to find the most suitable membrane with the least resistivity to fouling. Three different microfiltration (MF) and ultrafiltration (UF) membranes were operated to estimate their (i) membrane, (ii) cake, (iii) pore, and (iv) total resistances. The highest total resistance was observed in a polyethersulfone (PES) membrane (3.8 × 1010 m−1), while the lowest one was a UF polyvinylidene fluoride (PVDF) membrane with approximately 20 times lower resistance than the highest one. PVDF membranes showed lower total resistances than PES membranes. An MF or a 250 kDa UF membrane could be operated long-term in a membrane bioreactor with the least fouling potential. Full article
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Open AccessArticle Multi–Model Ensemble Approaches to Assessment of Effects of Local Climate Change on Water Resources of the Hotan River Basin in Xinjiang, China
Water 2017, 9(8), 584; doi:10.3390/w9080584
Received: 19 May 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 5 August 2017
PDF Full-text (7882 KB) | HTML Full-text | XML Full-text
Abstract
The effects of global climate change threaten the availability of water resources worldwide and modify their tempo-spatial pattern. Properly quantifying the possible effects of climate change on water resources under different hydrological models is a great challenge in ungauged alpine regions. By using
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The effects of global climate change threaten the availability of water resources worldwide and modify their tempo-spatial pattern. Properly quantifying the possible effects of climate change on water resources under different hydrological models is a great challenge in ungauged alpine regions. By using remote sensing data to support established models, this study aimed to reveal the effects of climate change using two models of hydrological processes including total water resources, peak flows, evapotranspiration, snowmelt and snow accumulation in the ungauged Hotan River Basin under future representative concentration pathway (RCP) scenarios. The results revealed that stream flow was much more sensitive to temperature variation than precipitation change and increased by 0.9–10.0% according to MIKE SHE or 6.5–10.5% according to SWAT. Increased evapotranspiration was similar for both models with a range of 7.6–31.3%. The snow-covered area shrank from 32.5% to 11.9% between the elevations of 4200–6400 m, respectively, and snow accumulation increased when the elevation exceeded 6400 m above sea level (asl). The results also suggested that the fully distributed and semi-distributed structures of these two models strongly influenced the responses to climate change. The study proposes a practical approach to assess the climate change effect in ungauged regions. Full article
(This article belongs to the Special Issue Adaptation Strategies to Climate Change Impacts on Water Resources)
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Open AccessArticle A Geospatial Approach for Identifying and Exploring Potential Natural Water Storage Sites
Water 2017, 9(8), 585; doi:10.3390/w9080585
Received: 10 May 2017 / Revised: 26 July 2017 / Accepted: 31 July 2017 / Published: 8 August 2017
PDF Full-text (4651 KB) | HTML Full-text | XML Full-text
Abstract
Across the globe, climate change is projected to affect the quantity, quality, and timing of freshwater availability. In western North America, there has been a shift toward earlier spring runoff and more winter precipitation as rain. This raises questions about the need for
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Across the globe, climate change is projected to affect the quantity, quality, and timing of freshwater availability. In western North America, there has been a shift toward earlier spring runoff and more winter precipitation as rain. This raises questions about the need for increased water storage to mitigate both floods and droughts. Some water managers have identified natural storage structures as valuable tools for increasing resiliency to these climate change impacts. However, identifying adequate sites and quantifying the storage potential of natural structures is a key challenge. This study addresses the need for a method for identifying and estimating floodplain water storage capacity in a manner that can be used by water planners through the development of a model that uses open-source geospatial data. This model was used to identify and estimate the storage capacity of a 0.33 km2 floodplain segment in eastern Montana, USA. The result is a range of storage capacities under eight natural water storage conditions, ranging from 900 m3 for small floods to 321,300 m3 for large floods. Incorporating additional hydraulic inputs, stakeholder needs, and stakeholder perceptions of natural storage into this process can help address more complex questions about using natural storage structures as ecosystem-based climate change adaptation strategies. Full article
(This article belongs to the Special Issue Adaptation Strategies to Climate Change Impacts on Water Resources)
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Open AccessArticle Wastewater Management Efficiency and Determinant Factors in the Chinese Industrial Sector from 2004 to 2014
Water 2017, 9(8), 586; doi:10.3390/w9080586
Received: 15 June 2017 / Revised: 1 August 2017 / Accepted: 1 August 2017 / Published: 5 August 2017
PDF Full-text (2142 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study analyzes industrial wastewater management efficiency using a Chinese provincial dataset from 2004 to 2014. The weighted Russell directional distance model is used to evaluate the efficiency of management practices. Determinants analysis was conducted based on governmental policy, pollution abatement, and market
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This study analyzes industrial wastewater management efficiency using a Chinese provincial dataset from 2004 to 2014. The weighted Russell directional distance model is used to evaluate the efficiency of management practices. Determinants analysis was conducted based on governmental policy, pollution abatement, and market factors to identify the main drivers of industrial wastewater management efficiency in China. The results indicate that the wastewater management efficiency improved in the eastern and central regions. However, there is a significant efficiency gap between provinces in the western region. Moreover, the main determinants of wastewater management efficiency differ among regions and pollutants. Full article
(This article belongs to the collection Water Policy Collection)
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Open AccessArticle Non-Dominated Sorting Harmony Search Differential Evolution (NS-HS-DE): A Hybrid Algorithm for Multi-Objective Design of Water Distribution Networks
Water 2017, 9(8), 587; doi:10.3390/w9080587
Received: 29 May 2017 / Revised: 27 July 2017 / Accepted: 3 August 2017 / Published: 7 August 2017
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Abstract
We developed a hybrid algorithm for multi-objective design of water distribution networks (WDNs) in the present study. The proposed algorithm combines the global search schemes of differential evolution (DE) with the local search capabilities of harmony search (HS) to enhance the search proficiency
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We developed a hybrid algorithm for multi-objective design of water distribution networks (WDNs) in the present study. The proposed algorithm combines the global search schemes of differential evolution (DE) with the local search capabilities of harmony search (HS) to enhance the search proficiency of evolutionary algorithms. This method was compared with other multi-objective evolutionary algorithms (MOEAs) including NSGA2, SPEA2, MOEA/D and extended versions of DE and HS combined with non-dominance criteria using several metrics. We tested the compared algorithms on four benchmark WDN design problems with two objective functions, (i) the minimization of cost and (ii) the maximization of resiliency as reliability measure. The results showed that the proposed hybrid method provided better optimal solutions and outperformed the other algorithms. It also exhibited significant improvement over previous MOEAs. The hybrid algorithm generated new optimal solutions for a case study that dominated the best-known Pareto-optimal solutions in the literature Full article
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Open AccessArticle Trade-Offs and Synergies in Ecosystem Service within the Three-Rivers Headwater Region, China
Water 2017, 9(8), 588; doi:10.3390/w9080588
Received: 1 June 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 8 August 2017
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Abstract
The Three-Rivers Headwaters region (TRHR) is an ecological shelter located in the northeast of the Tibetan Plateau, China, that provides environmental protection and regional sustainable development. This region also provides ecosystem services including water supply and soil conservation and exerts major impacts on
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The Three-Rivers Headwaters region (TRHR) is an ecological shelter located in the northeast of the Tibetan Plateau, China, that provides environmental protection and regional sustainable development. This region also provides ecosystem services including water supply and soil conservation and exerts major impacts on both its surroundings, as well as the whole of China. A number of ecological restoration projects have been initiated within the TRHR since 2000, including the creation of a natural reserve. Analyses of trends in land use/land cover (LULC), net primary productivity (NPP), water yield and soil conservation within the TRHR are presented based on regional climate and land use datasets and utilizing the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model in tandem with the double mass curve (DMC) approach. The results of this study reveal a series of correlations between ecosystem services and lead to four distinct conclusions. First, the amount of variation between 2000 and 2012 in each LULC type within the TRHR was small. In particular, grassland substitution occurred in high-altitude areas and increased in central areas. Second, NPP, water yield, soil conservation amount and the volume of exported phosphorus (P) decreased along an east-west gradient with values of 64.44%, 38.81%, 7.37% and −49.98% recorded, respectively, between 2000 and 2012. The ecosystem services of the Yellow River basin to the east of the TRHR generally improved over the study period, while those of the Yangtze River and Lancang River basins where enhanced to a lesser extent, and obvious degradation was observed in some local areas. Third, the ecosystem services provided by forested land were highest, followed by grassland and cultivated land, respectively. Fourth, synergistic relationships were observed within the TRHR between NPP, water yield and soil conservation amount, indicating that increasing NPP simultaneously increased the values for these related factors. Synergistic relationships were also recorded between water yield and the amount of exported P, suggesting that increases in the former cause a reduction in water purity. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle Reconciling Drought Vulnerability Assessment Using a Convergent Approach: Application to Water Security in the Elqui River Basin, North-Central Chile
Water 2017, 9(8), 589; doi:10.3390/w9080589
Received: 30 May 2017 / Revised: 31 July 2017 / Accepted: 2 August 2017 / Published: 8 August 2017
PDF Full-text (4583 KB) | HTML Full-text | XML Full-text
Abstract
Drought has been, is and most likely will remain one of the most significant socio-natural disasters affecting society and the environment worldwide. One priority objective in the adoption of national drought policies is to promote standardized approaches to vulnerability assessment. To reach this
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Drought has been, is and most likely will remain one of the most significant socio-natural disasters affecting society and the environment worldwide. One priority objective in the adoption of national drought policies is to promote standardized approaches to vulnerability assessment. To reach this objective, however, there is a need to address the noticeable lack of reconciliation between the two major epistemic frameworks that have been used to determine who is vulnerable and why: the so-called outcome and contextual frameworks. This study presents a novel procedure called the convergent approach to assess drought vulnerability under an integral framework. The procedure has been applied to the study of the vulnerability of water security to drought in water-use sectors in a basin located in north-central Chile. The study is justified by the role that drought plays as the major threat to water security in a context of global water crisis. The results show that the convergent approach outperforms traditional procedures such as those based on composite indicators, showing sound robustness and reaching sufficient levels of reliability and validity. The potential expansion of this approach to other applications, such as those related to global estimations of vulnerability to drought, is also discussed. Full article
(This article belongs to the Special Issue Drought Monitoring, Forecasting, and Risk Assessment)
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Open AccessArticle A Stepwise-Cluster Inference Model for Phenanthrene Immobilization at the Aqueous/Modified Palygorskite Interface
Water 2017, 9(8), 590; doi:10.3390/w9080590
Received: 29 April 2017 / Revised: 17 July 2017 / Accepted: 3 August 2017 / Published: 8 August 2017
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Abstract
A stepwise-cluster inference (SI) model was established through introducing stepwise-cluster analysis (SCA) into the phenanthrene immobilization process at the aqueous/modified palygorskite interface. SCA has the advantages of tackling the nonlinear relationships among environmental factors and the phenanthrene sorption amount in the immobilization process.
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A stepwise-cluster inference (SI) model was established through introducing stepwise-cluster analysis (SCA) into the phenanthrene immobilization process at the aqueous/modified palygorskite interface. SCA has the advantages of tackling the nonlinear relationships among environmental factors and the phenanthrene sorption amount in the immobilization process. The essence of SCA is to form a tree-based classification on a series of cutting or mergence procedures under given statistical criteria. The results indicated that SI could help develop a statistical relationship between environmental variables and the phenanthrene sorption amount, where discrete and nonlinear complexities exist. During the experiment, data were randomly sampled 10 times for model calibration and verification. The R2 (close to one) and root mean squared error (RMSE) (close to zero) values guaranteed the prediction accuracy of the model. Compared to other statistical methods, the calculation of R2 and RMSEs showed that SI was more straightforward for describing the nonlinear relationships and precisely fitting and predicting the immobilization of phenanthrene. Through the calculation of the input effects on the output in the SI model, the influence of environmental factors on phenanthrene immobilization were ranged in descending order as: initial phenanthrene concentration, ionic strength, pH, added humic acid dose, and temperature. It is revealed that SCA can be used to map the nonlinear and discrete relationships and elucidate the transport patterns of phenanthrene at the aqueous/modified palygorskite interface. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessFeature PaperArticle Decision-Making Methodology for Risk Management Applied to Imja Lake in Nepal
Water 2017, 9(8), 591; doi:10.3390/w9080591
Received: 8 June 2017 / Revised: 2 August 2017 / Accepted: 2 August 2017 / Published: 8 August 2017
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Abstract
Glacial retreat causes the formation of glacier lakes with the potential of producing glacial lake outburst floods (GLOFs). Imja Lake in Nepal is considered at risk for a GLOF. Communities in the path of a potential Imja GLOF are implementing adaptation projects, yet
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Glacial retreat causes the formation of glacier lakes with the potential of producing glacial lake outburst floods (GLOFs). Imja Lake in Nepal is considered at risk for a GLOF. Communities in the path of a potential Imja GLOF are implementing adaptation projects, yet no quantitative data or guidance is available to understand the benefits of these projects or how to weigh benefits against the cost of implementation. We develop and demonstrate a decision-making methodology for GLOF risk management, incorporating available scientific information and uncertainty. The methodology consists of (1) identifying flooding scenarios, (2) evaluating scenario consequences, and (3) performing an economic analysis of proposed adaptation projects. The methodology is applied to assess benefits in Dingboche of lowering Imja Lake by 3, 10 and 20 m. The results show that the baseline case (no lake lowering) has the lowest expected cost because of low valuation of agricultural land and homes in the literature. Nonetheless, the result is sensitive to changes in the analysis variables. We also found that lowering the lake by 10 or 20 m is efficient according only to the methodology used here; however, considering only direct economic damages and literature cost estimates, the costs outweigh the benefits for these projects. Full article
(This article belongs to the Special Issue Global Warming Impacts on Mountain Glaciers and Communities)
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Open AccessArticle Establishment of an Inventory for the Life Cycle Cost (LCC) Analysis of a Water Supply System
Water 2017, 9(8), 592; doi:10.3390/w9080592
Received: 7 March 2017 / Revised: 31 July 2017 / Accepted: 1 August 2017 / Published: 15 August 2017
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Abstract
This paper aimed to develop an inventory that is necessary for the life cycle cost (LCC) analysis of a water supply system. Based on an established inventory system, data items for each asset category were defined. The water supply system was divided into
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This paper aimed to develop an inventory that is necessary for the life cycle cost (LCC) analysis of a water supply system. Based on an established inventory system, data items for each asset category were defined. The water supply system was divided into pipelines, pumps and distribution facilities. Pipeline facilities that account for the majority of water supply systems were grouped, according to the purposes and functions of pipes, into conveyance facilities, transmission facilities, distribution facilities and supply facilities. The inventory of water supply systems were divided into five levels, and the higher the level, the more detailed facilities were classified. Basically, 12 items and diagnosis results were included in the system to distinguish the characteristics of each asset, and it was ensured that administrators could add or change items later if necessary. The data used in this study were established based on real data from the Yeong-Wol (YW) pipeline systems. Full article
(This article belongs to the Special Issue Water Networks Management: New Perspectives)
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Open AccessArticle Applications of Hydro-Chemical and Isotopic Tools to Improve Definitions of Groundwater Catchment Zones in a Karstic Aquifer: A Case Study
Water 2017, 9(8), 595; doi:10.3390/w9080595
Received: 12 June 2017 / Revised: 2 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method
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Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method in all European Union member states. One of the criteria used to establish GPZs is to define contributing catchment areas (CCAs). This methodology has been applied to the Sierra de Cañete, a region comprising a carbonate aquifer in the province of Malaga, Spain. The tools used to define CCAs are hydro-chemical and isotopic characterizations, namely water isotopes (i.e., 2H, 18O and tritium) and the isotopes of dissolved sulfates (i.e., 34S and 18O). Traditionally, the Sierra de Cañete aquifer has been divided into six sectors. Hydro-chemical and isotopic characterization differentiated between two large areas in the carbonate aquifer. The southern part presents younger water that is the result of faster recharge and that shows a high level of karstification, while the northern area has a slower flow, and recharge is produced over several years. In addition, the northern part is hydraulically connected to an alluvial aquifer (i.e., Llanos de Almargen) that borders the Sierra de Cañete to the north. This aquifer has high levels of pollution due to agricultural and livestock activities carried out in the Llanos de Almargen area. This pollution is transmitted to the carbonate aquifer when groundwater depletion occurs. Therefore, the Sierra de Cañete GPZ needs to be extended to include the Llanos de Almargen aquifer. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Chance-Constrained Dynamic Programming for Multiple Water Resources Allocation Management Associated with Risk-Aversion Analysis: A Case Study of Beijing, China
Water 2017, 9(8), 596; doi:10.3390/w9080596
Received: 29 April 2017 / Revised: 8 July 2017 / Accepted: 3 August 2017 / Published: 11 August 2017
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Abstract
Water shortage and water pollution have become major problems hindering socio-economic development. Due to the scarcity of water resources, the conflict between water supply and demand is becoming more and more prominent, especially in urban areas. In order to ensure the safety of
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Water shortage and water pollution have become major problems hindering socio-economic development. Due to the scarcity of water resources, the conflict between water supply and demand is becoming more and more prominent, especially in urban areas. In order to ensure the safety of urban water supply, many cities have begun to build reservoirs. However, few previous studies have focused on the optimal allocation of water resources considering storage reservoirs. In this study, a multi-water resources and multiple users chance-constrained dynamic programming (MMCDP) model has been developed for water resources allocation in Beijing, China, which introduces reservoir and chance-constrained programming into the dynamic programming decision-making framework. The proposed model can distribute water to different departments according to their respective demands in different periods. Specifically, under the objective of maximal benefits, the water allocation planning and the amount of water stored in a reservoir for each season under different feasibility degrees (violating constraints or available water resources situations) can be obtained. At the same time, the model can be helpful for decision-makers to identify the uncertainty of water-allocation schemes and make a desired compromise between the satisfaction degree of the economic benefits and the feasibility degree of constraints. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Mitigation Options for Future Water Scarcity: A Case Study in Santa Cruz Island (Galapagos Archipelago)
Water 2017, 9(8), 597; doi:10.3390/w9080597
Received: 1 May 2017 / Revised: 2 August 2017 / Accepted: 9 August 2017 / Published: 12 August 2017
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Abstract
Santa Cruz Island (Galápagos Archipelago), like many other tourist islands, is currently experiencing an exponential increase in tourism and local population growth, jeopardizing current and future water supply. An accurate assessment of the future water supply/demand balance is crucial to capital investment for
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Santa Cruz Island (Galápagos Archipelago), like many other tourist islands, is currently experiencing an exponential increase in tourism and local population growth, jeopardizing current and future water supply. An accurate assessment of the future water supply/demand balance is crucial to capital investment for water infrastructure. This paper aims to present five intervention strategies, which are suggested to solve the future water crisis. The strategies combined include environmentally sustainable options such as rainwater harvesting, greywater recycling and water demand management, as well as desalination. These strategies were evaluated under four population growth scenarios (very fast, fast, moderate and slow growths) by using several Key Performance Indicators (KPI’s) including water demand, leakage levels, total costs, energy consumption, rainwater delivered and greywater recycled. Moreover, it also aims to develop a methodology for similar islands, using the WaterMet2 modelling approach, a tool for integrated of sustainable-based performance of urban water systems. The results obtained show that by 2044 only a small portion of the future water demand can be covered assuming business as usual. Therefore, desalination seems to be the most viable option in order to mitigate the lack of water at the end of the planning period considering the growth trends. However, strategies comprising more environmentally friendly alternatives may be sufficient, but only under slow population growth scenarios. Full article
(This article belongs to the Special Issue Urban Water Cycle Modelling and Management)
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Open AccessArticle Water Resources of the Black Sea Catchment under Future Climate and Landuse Change Projections
Water 2017, 9(8), 598; doi:10.3390/w9080598
Received: 11 April 2017 / Revised: 13 July 2017 / Accepted: 6 August 2017 / Published: 12 August 2017
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Abstract
As water resources become further stressed due to increasing levels of societal demand, understanding the effect of climate and landuse change on various components of the water cycle is of strategic importance. In this study we used a previously developed hydrologic model of
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As water resources become further stressed due to increasing levels of societal demand, understanding the effect of climate and landuse change on various components of the water cycle is of strategic importance. In this study we used a previously developed hydrologic model of the Black Sea Catchment (BSC) to assess the impact of potential climate and landuse changes on the fresh water availability. The BSC model was built, calibrated, and validated against observed daily river discharge for the period of 1973–2006 using the Soil and Water Assessment Tool (SWAT) as the modeling tool. We employed the A2 and B2 scenarios of 2017–2050 generated by the Danish Regional Climate Model (HIRHAM), and four potential future landuse scenarios based on the Intergovernmental Panel of Climate Change (IPCC)’s special report on emissions scenarios (SRES) storylines, to analyze the impact of climate change and landuse change on the water resources of the BSC. The detailed modeling and the ensemble of the scenarios showed that a substantial part of the catchment will likely experience a decrease in freshwater resources by 30 to 50%. Full article
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Open AccessArticle How Efficient Are Semi-Natural Ponds in Assimilating Wastewater Effluents? Application to Fuente de Piedra Ramsar, Mediterranean Salt Lake (South of Spain)
Water 2017, 9(8), 600; doi:10.3390/w9080600
Received: 29 June 2017 / Revised: 3 August 2017 / Accepted: 9 August 2017 / Published: 12 August 2017
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Abstract
This work concerns the case study of a Mediterranean Ramsar salt lake (Fuente de Piedra, southern Spain) that receives the treated wastewater of the local village treatment plant. The wastewater goes through a system of canals, water dams, and three semi-natural ponds that
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This work concerns the case study of a Mediterranean Ramsar salt lake (Fuente de Piedra, southern Spain) that receives the treated wastewater of the local village treatment plant. The wastewater goes through a system of canals, water dams, and three semi-natural ponds that were built in 2005. This work aims to investigate the capacity of the system to assimilate the impact of wastewater effluents on Lake Fuente de Piedra. For this, four points were sampled on 27–29 April 2016, at the inlet and the outlet points of the first and the third semi-natural ponds, with three replicates each. Temperature, pH, and conductivity at the inlet were 19.62 °C, 7.99, and 3262.67 μS/cm, respectively, and increased through the pond system by 7.59%, 8.04%, and 37.34%, respectively. Phytoplankton concentration indicators decreased from the inlet point to the outlet point (chlorophyll a from >500 to <20mg/L), as did the biovolume (from >5 × 1010 to 4.3 × 109 μm3/mL). Zooplankton biovolume, in contrast, increased three orders of magnitude from the inlet (3.5 × 107 μm3/mL) to the outlet point (1.6 × 109 μm3/mL). Heterotrophic bacteria (1.29 × 105 cfu/mL) and faecal enterococci (1033 ± 351 cfu/100 mL) were high at the inlet point, but decreased at the outlet point by almost three orders of magnitude. Total phosphorous and total nitrogen decreased 40.3% and 23.1% through the pond system. The results showed an improvement in water quality in its passage through the built system. Additionally, as permanent wetlands with acceptable water quality, the water system attracts wild fauna during the dry summer, leading to the conclusion that these semi-natural or artificial wetlands should be extrapolated to other aquatic ecosystems (Mediterranean wetlands) that receive contributions of residual waters. Better functioning of the treatment plant is desirable to improve the conservation of the Ramsar and adjacent wetlands systems. Full article
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Open AccessArticle Sediment-Water Methane Flux in a Eutrophic Pond and Primary Influential Factors at Different Time Scales
Water 2017, 9(8), 601; doi:10.3390/w9080601
Received: 11 June 2017 / Revised: 21 July 2017 / Accepted: 10 August 2017 / Published: 14 August 2017
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Abstract
Water bodies are major areas for methane release. Eutrophic water bodies may promote methane flux. The sediment-water interface is the major location for methane release, and studies on sediment-water interactions are necessary to regulate methane release in water. However, relevant studies on methane
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Water bodies are major areas for methane release. Eutrophic water bodies may promote methane flux. The sediment-water interface is the major location for methane release, and studies on sediment-water interactions are necessary to regulate methane release in water. However, relevant studies on methane flux at the sediment-water interface are limited due to methodological difficulties. Using an innovative gas trapping device, this study investigated the seasonal characteristics and diel variation in summer methane flux from eutrophic water bodies and analyzed the correlations between temperature, dissolved oxygen (DO), different forms of nitrogen and the methane flux at different time scales. The results showed that methane flux in the eutrophic pond was high and had distinct seasonal variations and diel variations: the average value was 2.81 ± 0.19 mmol m−2 h−1 in summer, which was significantly greater than that in spring (0.62 ± 0.14 mmol m−2 h−1), autumn (0.63 ± 0.10 mmol m−2 h−1) (p < 0.01) and winter (approached zero). The diel characteristics of methane flux in summer exhibited a unimodal pattern of increase at night and decrease during the day. The correlation analysis showed that the sediment-water methane flux rate of the water body was significantly positively correlated with the temperature and NH4+ concentration and significantly negatively correlated with DO, NO3 and NO2 concentration. Meanwhile, among different time scales, the correlations between NO3/NH4+ concentration and methane flux were the highest at the diel scale in summer (R2 = 0.68, 0.87 respectively) when the temperature and DO vibration was low and the relationship between temperature/DO and methane flux was poor (R2 = 0.45, 0.87 respectively). This study considered that higher NH4+-N and lower NO3-N/NO2-N content in eutrophic water could have an effect on the high methane flux in summer as well as the low dissolved oxygen content. Full article
(This article belongs to the Special Issue Eutrophication of Waterways: An Old Problem with Modern Consequences)
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Open AccessArticle Distributed Hydrological Modeling: Determination of Theoretical Hydraulic Potential & Streamflow Simulation of Extreme Hydrometeorological Events
Water 2017, 9(8), 602; doi:10.3390/w9080602 (registering DOI)
Received: 12 June 2017 / Revised: 28 July 2017 / Accepted: 9 August 2017 / Published: 17 August 2017
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Abstract
The progressive change in climatic conditions worldwide has increased frequency and severity of extreme hydrometeorological events (EHEs). México is an example that has been affected by the occurrence of EHE leading to economic, social, and environmental losses. The objective of this research was
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The progressive change in climatic conditions worldwide has increased frequency and severity of extreme hydrometeorological events (EHEs). México is an example that has been affected by the occurrence of EHE leading to economic, social, and environmental losses. The objective of this research was to apply a Canadian distributed hydrological model (DHM) to tropical conditions and to evaluate its capacity to simulate flows in a basin in the central Gulf of Mexico. In addition, the DHM (once calibrated and validated) was used to calculate the theoretical hydraulic power (THP) and the performance to predict streamflow before the presence of an EHE. The results of the DHM show that the goodness of fit indicators between the observed and simulated flows in the calibration process Nash-Sutcliffe efficiency (NSE) = 0.83, ratio of the root mean square error to the standard deviation of measured data (RSR) = 0.41, and percent bias (PBIAS) = −4.3) and validation (NSE = 0.775, RSR = 0.4735, and PBIAS = 2.45) are satisfactory. The DHM showed its applicability: determination of THP showed that the mean flows are in synchrony with the order of the river reaches and streamflow simulation of 13 EHEs (NSE = 0.78 ± 0.13, RSR = 0.46 ± 0.14 and PBIAS = −0.48 ± 7.5) confirmed a reliable efficiency. This work can serve as a tool for identifying vulnerabilities before floods and for the rational and sustainable management of water resources. Full article
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Open AccessArticle Understanding the Temperature Variations and Thermal Structure of a Subtropical Deep River-Run Reservoir before and after Impoundment
Water 2017, 9(8), 603; doi:10.3390/w9080603
Received: 27 June 2017 / Revised: 2 August 2017 / Accepted: 10 August 2017 / Published: 15 August 2017
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Abstract
A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013–2014) using measured data as model input. It was calibrated using observed temperature
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A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013–2014) using measured data as model input. It was calibrated using observed temperature profiles near the dam and the outflow temperatures. Observed daily temperatures at four gauging stations upstream or downstream of XLDR before (2000–2012) and after the impoundment (4 May 2013) were analyzed and fitted with a sine function representing seasonal temperature variation. The fitted annual temperature phase shifts showed no phase delay in XLDR area before the impoundment but revealed a phase delay about 17 days between outflow and inflow after the impoundment, which was not caused by the air temperature variation. The simulated temperatures verified a similar phase delay after the impoundment. The simulated temperatures, water ages, and vertical temperature gradients demonstrated an average metalimnetic deepening rate of 0.49 m/day (average inflow ~4500 m3/s) while the largest rate due to massive inflow (~15,000 m3/s) was 1.67 m/day. The W2 model was run under hypothetic scenarios of different inflow/outflow rates and outflow withdrawn elevations. The results revealed that greater inflow/outflow rate could lead to higher metalimnetic deepening rate and smaller outflow phase delay, while deeper outflow withdrawn could lead to deeper metalimnion and larger epilimnetic depth. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle A Web Based Interface for Distributed Short-Term Soil Moisture Forecasts
Water 2017, 9(8), 604; doi:10.3390/w9080604
Received: 26 June 2017 / Revised: 31 July 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
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Abstract
Agricultural non-point source (NPS) pollution is a source of water quality impairment, and demonstrates widely varying spatial and temporal pollution potential. Many efforts to protect water quality are based on seasonal and annual estimates of pollutant loss potential (NRCS 590 nutrient management standard,
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Agricultural non-point source (NPS) pollution is a source of water quality impairment, and demonstrates widely varying spatial and temporal pollution potential. Many efforts to protect water quality are based on seasonal and annual estimates of pollutant loss potential (NRCS 590 nutrient management standard, P-Index) that inadequately address the hydrologic processes driving NPS pollution. One barrier to adopting practices that address NPS pollution is a lack of tools capable of transferring information at sufficient spatial and temporal resolution so that end-users can make informed decisions. We introduce a web-based system displaying distributed hydrologic forecasts using free and open source software. The system consists of three primary components: (1) a hydrology model that provides short-term distributed forecasts; (2) a data structure capable of re-structuring large, high resolution rasters; (3) an interface employing adaptive map-viewing technology that allows end-users to interact with the data to avoid high-risk areas when planning agricultural practices. Full article
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Open AccessFeature PaperArticle Watershed Variability in Streambank Erodibility and Implications for Erosion Prediction
Water 2017, 9(8), 605; doi:10.3390/w9080605
Received: 15 June 2017 / Revised: 8 August 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
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Abstract
Two fluvial erosion models are commonly used to simulate the erosion rate of cohesive soils: the empirical excess shear stress model and the mechanistic Wilson model. Both models include two soil parameters, the critical shear stress (τc) and the erodibility
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Two fluvial erosion models are commonly used to simulate the erosion rate of cohesive soils: the empirical excess shear stress model and the mechanistic Wilson model. Both models include two soil parameters, the critical shear stress (τc) and the erodibility coefficient (kd) for the excess shear stress model and b0 and b1 for the Wilson model. Jet erosion tests (JETs) allow for in-situ determination of these parameters. JETs were completed at numerous sites along two streams in each the Illinois River and Fort Cobb Reservoir watersheds. The objectives were to use JET results from these streambank tests to investigate variability of erodibility parameters on the watershed scale and investigate longitudinal trends in streambank erodibility. The research also determined the impact of this variability on lateral retreat predicted by a process-based model using both the excess shear stress model and the Wilson model. Parameters derived from JETs were incorporated into a one-dimensional process-based model to simulate bank retreat for one stream in each watershed. Erodibility parameters varied by two to five and one to two orders of magnitude in the Illinois River watershed and Fort Cobb Reservoir watershed, respectively. Less variation was observed in predicted retreat by a process-based model compared to the input erodibility parameters. Uncalibrated erodibility parameters and simplified applied shear stress estimates failed to match observed lateral retreats suggesting the need for model calibration and/or advanced flow modeling. Full article
(This article belongs to the Special Issue Streambank Erosion: Monitoring, Modeling and Management)
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Open AccessArticle Agreement of Four Equations for Computing Dewfall in Northern Germany
Water 2017, 9(8), 607; doi:10.3390/w9080607
Received: 3 June 2017 / Revised: 2 August 2017 / Accepted: 8 August 2017 / Published: 15 August 2017
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Abstract
The energy balance (EB), turbulent vapour transport (TVT), Penman-Monteith (PM) and Bowen ratio energy balance (BREB) equation were used to estimate dewfall based on meteorological data. Initially there were big disagreements between the estimates from these four equations. However, after multiplying the heat
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The energy balance (EB), turbulent vapour transport (TVT), Penman-Monteith (PM) and Bowen ratio energy balance (BREB) equation were used to estimate dewfall based on meteorological data. Initially there were big disagreements between the estimates from these four equations. However, after multiplying the heat and vapour conductance terms by 0.33 the agreement was much better. This implies that the disagreements derived from improper conductance values. Initially we did not consider the effect of atmospheric stability on the conductances. With stability correction the conductances were on average 0.5 times the values without stability correction. To arrive at the aforementioned 0.33, the conductances with stability correction still need to be lower by a factor of 0.66. The value of the von Karman constant and the relationships for the zero plane displacement and the roughness length we used in our conductance computations are widely used, but not the only possible ones. With different values and relationships also suggested in the literature one can reach this factor. However, it is also possible that our wind speed data contributed to the fact that the conductances we computed were too high. Their computation for a given canopy—atmosphere system requires wind speeds from a wind profile in equilibrium with the vegetation. This in turn requires an adequate fetch around the investigated surface. The highly varied vegetation in and around the site where the study was conducted makes adequate fetch rather doubtful. To obtain valid conductance values the atmospheric stability conditions must be considered, the appropriate values for the von Karman constant, the zero plane displacement and roughness length must be used, and there must be adequate fetch. The BREB equation does not contain a conductance term and therefore does not suffer from the problems just stated. The other three equations do. However, the BREB, like the EB and TVT equations, need the surface temperature which is not routinely measured. This then leaves the PM equation from which this temperature has been eliminated as the only option. Hence, in a future study dewfall estimates from the PM equation should be compared with direct measurements with a high precision weighing lysimeter. Full article
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Open AccessArticle Improved Medium- and Long-Term Runoff Forecasting Using a Multimodel Approach in the Yellow River Headwaters Region Based on Large-Scale and Local-Scale Climate Information
Water 2017, 9(8), 608; doi:10.3390/w9080608
Received: 21 June 2017 / Revised: 2 August 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
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Abstract
Medium- and long-term runoff forecasting is essential for hydropower generation and water resources coordinated regulation in the Yellow River headwaters region. Climate change has a great impact on runoff within basins, and incorporating different climate information into runoff forecasting can assist in creating
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Medium- and long-term runoff forecasting is essential for hydropower generation and water resources coordinated regulation in the Yellow River headwaters region. Climate change has a great impact on runoff within basins, and incorporating different climate information into runoff forecasting can assist in creating longer lead-times in planning periods. In this paper, a multimodel approach was developed to further improve the accuracy and reliability of runoff forecasting fully considering of large-scale and local-scale climatic factors. First, with four large-scale atmospheric oscillations, sea surface temperature, precipitation, and temperature as the predictors, multiple linear regression (MLR), radial basis function neural network (RBFNN), and support vector regression (SVR) models were built. Next, a Bayesian model averaging (BMA)-based multimodel was developed using weighted MLR, RBFNN, and SVR models, and the performance of the BMA-based multimodel was compared to those of the MLR, RBFNN, and SVR models. Finally, the high-runoff performance of these four models was further analyzed to prove the effectiveness of each model. The BMA-based multimodel performed better than those of the other models, as well as high-runoff forecasting. The results also revealed that the performance of the forecasting models with multiple climatic factors were generally superior to that without climatic factors. The BMA-based multimodel with climatic factors not only provides a promising, reliable method for medium- and long-term runoff forecasting, but also facilitates uncertainty estimation under different confidence intervals. Full article
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Open AccessArticle Assessment of Nitrogen Inputs into Hunt River by Onsite Wastewater Treatment Systems via SWAT Simulation
Water 2017, 9(8), 610; doi:10.3390/w9080610
Received: 15 June 2017 / Revised: 20 July 2017 / Accepted: 8 August 2017 / Published: 16 August 2017
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Abstract
Nonpoint source nitrogen pollution is difficult to effectively model in groundwater systems. This study aims to elucidate anthropogenic nonpoint source pollution discharging into Potowomut Pond and ultimately Narragansett Bay. Hydrologic modeling with Soil and Water Assessment Tool (SWAT) and SWAT Calibration and Uncertainty
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Nonpoint source nitrogen pollution is difficult to effectively model in groundwater systems. This study aims to elucidate anthropogenic nonpoint source pollution discharging into Potowomut Pond and ultimately Narragansett Bay. Hydrologic modeling with Soil and Water Assessment Tool (SWAT) and SWAT Calibration and Uncertainty Program (SWAT-CUP) was used to simulate streamflow and nitrogen levels in the Hunt River with and without onsite wastewater treatment systems (OWTS). The objective of this study was to determine how input of OWTS data impacts nitrogen loading into the Hunt River Watershed in Rhode Island, USA. The model was simulated from 2006 to 2014, calibrated from 2007 to 2011 and validated from 2012 to 2014. Observed streamflow data was sourced from a US Geological Survey gauge and nitrogen loading data from University of Rhode Island Watershed Watch (URIWW). From the results, adding OWTS data to the SWAT simulation produced a better calibration and validation fit for total fit (Nash–Sutcliffe Efficiency (NSE) = 0.50 calibration, 0.78 validation) when compared with SWAT simulation without OWTS data (NSE = −1.3 calibration, −6.95) validation. Full article
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Open AccessArticle Aspects of Hexavalent Chromium Pollution of Thebes Plain Aquifer, Boeotia, Greece
Water 2017, 9(8), 611; doi:10.3390/w9080611
Received: 12 June 2017 / Revised: 4 August 2017 / Accepted: 8 August 2017 / Published: 16 August 2017
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Abstract
The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of
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The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of 20 samples from the study area was conducted as well as an isotopic analysis of Cr and Sr isotopes. Hexavalent chromium pollution can be triggered by human pollutant activity or specific geological environments. Stable Cr isotopic analysis gave δ53Cr positive values in several samples which supports the second hypothesis, but the limitations of that theory do not allow safe conclusions in all cases. Nitrates and Sr ratios suggest fertilizer contamination and the presence of SiO2-leaching of silicate rocks. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle Exploring Jeddah Floods by Tropical Rainfall Measuring Mission Analysis
Water 2017, 9(8), 612; doi:10.3390/w9080612
Received: 13 June 2017 / Revised: 31 July 2017 / Accepted: 10 August 2017 / Published: 16 August 2017
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Abstract
Estimating flash floods in arid regions is a challenge arising from the limited time preventing mitigation measures from being taken, which results in fatalities and property losses. Here, Tropical Rainfall Measuring Mission (TRMM) Multi Satellite Precipitation Analysis (TMPA) Real Time (RT) 3B2RT data
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Estimating flash floods in arid regions is a challenge arising from the limited time preventing mitigation measures from being taken, which results in fatalities and property losses. Here, Tropical Rainfall Measuring Mission (TRMM) Multi Satellite Precipitation Analysis (TMPA) Real Time (RT) 3B2RT data are utilized in estimating floods that occurred over the city of Jeddah located in the western Kingdom of Saudi Arabia. During the 2000–2014 period, six floods that were effective on 19 days occurred in Jeddah. Three indices, constant threshold (CT), cumulative distribution functions (CDFs) and Jeddah flood index (JFI), were developed using 15-year 3-hourly 3B42RT. The CT calculated, as 10.37 mm/h, predicted flooding on 14 days, 6 of which coincided with actual flood-affected days (FADs). CDF thresholds varied between 87 and 93.74%, and JFI estimated 28 and 20 FADs where 8 and 7 matched with actual FADs, respectively. While CDF and JFI did not miss any flood event, CT missed the floods that occurred in the heavy rain months of January and December. The results are promising despite that only rainfall rates, i.e., one parameter out of various flood triggering mechanisms, i.e., soil moisture, topography and land use, are used. The simplicity of the method favors its use in TRMM follow-on missions such as the Global Precipitation Measurement Mission (GPM). Full article
Open AccessArticle Wet Spells and Associated Moisture Sources Anomalies across Danube River Basin
Water 2017, 9(8), 615; doi:10.3390/w9080615 (registering DOI)
Received: 29 May 2017 / Revised: 10 August 2017 / Accepted: 15 August 2017 / Published: 17 August 2017
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Abstract
The Danube River Basin is the second longest catchment basin in Europe and exhibits intense climatological diversity. In recent decades, the frequency and intensity of daily precipitation extremes have suffered from an increment in many parts of the world, including Central and Eastern
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The Danube River Basin is the second longest catchment basin in Europe and exhibits intense climatological diversity. In recent decades, the frequency and intensity of daily precipitation extremes have suffered from an increment in many parts of the world, including Central and Eastern Europe. Wet spells are defined by the number of consecutive rainy days with different thresholds. The identification of wet spells and their trends in the rainfall time is very important for many sectors, such as agriculture, ecology, hydrology and water resources. Wet spells can lead to extreme events and cause floods and other disasters. In this study, we will attempt to characterise global precipitation in the context of wet spells and associated precipitation depth of wet spells in the Danube River Basin area using daily precipitation data, as well as analysing different approaches to identifying wet spells. The ten most intense wet spells were detected, and the most intense, which occurred on 23 September 1996, was studied in depth in terms of precipitation and associated anomalies, the synoptic situation and the anomalous transport of moisture using a Lagrangian approach. The existence of a marked west-east dipole in the field of sea level pressure between the Atlantic Ocean and the eastern Mediterranean leads to the anomalous moisture transport from the Northern Atlantic Ocean to the Mediterranean Sea, where a higher available amount of moisture existed, and subsequently penetrated within the low positioned over the Danube River Basin. In addition, an Atmospheric River was also responsible for the wet conditions in the Danube River Basin. The combination of all these factors was responsible for the extreme precipitation linked with the wet spell. Full article
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Open AccessArticle Spatiotemporal Patterns of Crop Irrigation Water Requirements in the Heihe River Basin, China
Water 2017, 9(8), 616; doi:10.3390/w9080616 (registering DOI)
Received: 30 June 2017 / Revised: 14 August 2017 / Accepted: 15 August 2017 / Published: 17 August 2017
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Abstract
Agricultural expansion, population growth, rapid urbanization, and climate change have all significantly impacted global water supply and demand and have led to a number of negative consequences including ecological degradation and decreases in biodiversity, especially in arid and semi-arid areas. The agricultural sector
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Agricultural expansion, population growth, rapid urbanization, and climate change have all significantly impacted global water supply and demand and have led to a number of negative consequences including ecological degradation and decreases in biodiversity, especially in arid and semi-arid areas. The agricultural sector consumes the most water globally; crop irrigation alone uses up more than 80% of available agricultural water. Thus, to maintain sustainable development of the global economy and ecosystems, it is crucial to effectively manage crop irrigation water. We focus on the arid and semi-arid Heihe River Basin (HRB), China, as a case study in this paper, extracting spatiotemporal information on the distribution of crop planting using multi-temporal Thematic Mapper and Enhanced Thematic Mapper Plus (TM/ETM+) remote sensing (RS) images. We estimate the spatiotemporal crop irrigation water requirements (IWRc) using the Food and Agriculture Organization of the United Nations (FAO) Penman-Monteith method and reveal variations in IWRc. We also analyze the impact of changes in crop planting structure on IWRc and discuss strategies for the rational allocation of irrigation water as well as policies to alleviate imbalance between water supply and demand. The results of this study show that effective rainfall (ER) decreases upstream-to-downstream within the HRB, while crop evapotranspiration under standard conditions (ETc) increases, leading to increasing spatial variation in IWRc from zero up to 150 mm and between 300 and 450 mm. Data show that between 2007 and 2012, annual mean ER decreased from 139.49 to 106.29 mm, while annual mean ETc increased from 483.87 to 500.38 mm, and annual mean IWRc increased from 339.95 to 370.11 mm. Data show that monthly mean IWRc initially increased before decreasing in concert with crop growth. The largest values for this index were recorded during the month of June; results show that IWRc for May and June decreased by 8.14 and 11.67 mm, respectively, while values for July increased by 5.75 mm between 2007 and 2012. These variations have helped to ease the temporal imbalance between water supply and demand. Mean IWRc values for oilseed rape, corn, barley, and other crops all increased over the study period, from 208.43, 349.35, 229.26, and 352.85 mm, respectively, in 2007, to 241.81, 393.10, 251.17, and 378.86 mm, respectively, in 2012. At the same time, the mean IWRc of wheat decreased from 281.53 mm in 2007 to 266.69 mm in 2012. Mainly because of changes in planting structure, the total IWRc for the HRB in 2012 reached 2692.58 × 106 m3, an increase of 332.16 × 106 m3 (14.07%) compared to 2007. Data show that 23.11% (76.77 × 106 m3) of this increase is due to crop transfers, while the remaining 76.89% (255.39 × 106 m3) is the result of the rapid expansion of cultivated land. Thus, to maintain both the sustainable development and ecological security of the HRB, it is crucial to efficiently manage and utilize agricultural water in light of spatiotemporal patterns in IWRc changes as well as IWRc variations between different crops. The cultivation of water-demanding crops and the further expansion of agricultural land should also be avoided. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
Open AccessArticle Recent Sedimentation Rates of Shallow Lakes in the Middle and Lower Reaches of the Yangtze River: Patterns, Controlling Factors and Implications for Lake Management
Water 2017, 9(8), 617; doi:10.3390/w9080617 (registering DOI)
Received: 7 June 2017 / Revised: 10 August 2017 / Accepted: 10 August 2017 / Published: 17 August 2017
PDF Full-text (4505 KB) | Supplementary Files
Abstract
Significantly increased sedimentation rates (SRs) in lakes worldwide in recent decades due to higher inputs of silt and eutrophication have led to significant environmental problems such as lake size diminishment and degraded water quality. Many lakes in the middle and lower reaches of
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Significantly increased sedimentation rates (SRs) in lakes worldwide in recent decades due to higher inputs of silt and eutrophication have led to significant environmental problems such as lake size diminishment and degraded water quality. Many lakes in the middle and lower reaches of the Yangtze River basin (MLYB) have followed this pattern. For effective lake management, it is essential to understand the pattern and drivers of SRs in these lakes. Fourteen typical lakes in the MLYB were chosen to examine the spatiotemporal patterns of SRs and identify the drivers over different time periods. Since 1900, SRs increased from <0.2 to 0.3–0.6 g·cm−2·year−1, particularly notable during 1930–1990. Combined with climatic factors, SR correlated negatively with lake (catchment) size and abundance of aquatic vegetation, whereas other lake features including nutrient status did not contribute significantly to the variation in SRs, due to the fast decomposition processes of organic matter in shallow lakes. Detrimental land use practices especially reclamation for croplands and rapid urbanization was revealed to elevate SRs pronouncedly. We propose various management strategies aiming to maintain SR reference condition at ~0.16 ± 0.08 g·cm−2·year−1, which is analogous to the SR value between 1850 and 1900. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)

Review

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Open AccessReview A Review of Phosphorus Removal Structures: How to Assess and Compare Their Performance
Water 2017, 9(8), 583; doi:10.3390/w9080583
Received: 29 June 2017 / Revised: 27 July 2017 / Accepted: 1 August 2017 / Published: 10 August 2017
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Abstract
Controlling dissolved phosphorus (P) losses to surface waters is challenging as most conservation practices are only effective at preventing particulate P losses. As a result, P removal structures were developed to filter dissolved P from drainage water before reaching a water body. While
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Controlling dissolved phosphorus (P) losses to surface waters is challenging as most conservation practices are only effective at preventing particulate P losses. As a result, P removal structures were developed to filter dissolved P from drainage water before reaching a water body. While many P removal structures with different P sorption materials (PSMs) have been constructed over the past two decades, there remains a need to evaluate their performances and compare on a normalized basis. The purpose of this review was to compile performance data of pilot and field-scale P removal structures and present techniques for normalization and comparison. Over 40 studies were normalized by expressing cumulative P removal as a function of cumulative P loading to the contained PSM. Results were further analyzed as a function of retention time (RT), inflow P concentration, and type of PSM. Structures treating wastewater were generally more efficient than non-point drainage water due to higher RT and inflow P concentrations. For Ca-rich PSMs, including slag, increased RT allowed for greater P removal. Among structures with low RT and inflow P concentrations common to non-point drainage, Fe-based materials had an overall higher cumulative removal efficiency compared to non-slag and slag materials. Full article
(This article belongs to the Special Issue Additives in Stormwater Filters for Enhanced Pollutant Removal)
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Other

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Open AccessTechnical Note Optimized Subsurface Irrigation System (OPSIS): Beyond Traditional Subsurface Irrigation
Water 2017, 9(8), 599; doi:10.3390/w9080599
Received: 25 May 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 12 August 2017
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Abstract
Technologies that ensure the availability of water for crops need to be developed in order for agriculture to be sustainable in the face of climate change. Irrigation is costly, so technologies need to be improved or newly developed, not only with the aim
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Technologies that ensure the availability of water for crops need to be developed in order for agriculture to be sustainable in the face of climate change. Irrigation is costly, so technologies need to be improved or newly developed, not only with the aim of the sustainable use of precious water resources, but also with the aim of reducing associated labor and energy costs, which lead to higher production costs. OPSIS (optimized subsurface irrigation system) is a super water-saving subsurface irrigation system developed to irrigate upland crops by soil capillarity. It is an environmentally-friendly, solar-powered automatic irrigation method with minimum energy consumption and operational costs. In soils vulnerable to drought damage, OPSIS can outperform other irrigation methods. This technical note introduces OPSIS. Full article
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