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Water, Volume 7, Issue 4 (April 2015) , Pages 1324-1768

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Open AccessArticle
General Rainfall Patterns in Indonesia and the Potential Impacts of Local Seas on Rainfall Intensity
Water 2015, 7(4), 1751-1768; https://doi.org/10.3390/w7041751
Received: 30 December 2014 / Revised: 21 March 2015 / Accepted: 14 April 2015 / Published: 22 April 2015
Cited by 11 | Viewed by 3194 | PDF Full-text (6318 KB) | HTML Full-text | XML Full-text
Abstract
The relationships between observed rainfall, El Niño/Southern Oscillation (ENSO) and sea surface temperature (SST) variations in the Pacific and Indian Oceans were analyzed using a 1° latitude–longitude grid over Indonesia. The Global Summary of the Day rainfall records provide 26 years of rainfall [...] Read more.
The relationships between observed rainfall, El Niño/Southern Oscillation (ENSO) and sea surface temperature (SST) variations in the Pacific and Indian Oceans were analyzed using a 1° latitude–longitude grid over Indonesia. The Global Summary of the Day rainfall records provide 26 years of rainfall data (January 1985 to August 2010) for 23 stations throughout the Indonesian islands. The ENSO and SST variations were calculated using the Multivariate ENSO Index (MEI), the Pacific Decadal Oscillation (PDO), NINO1 + 2, NINO3, NINO3.4, NINO4, the Dipole Mode Index (DMI) for the Indian Ocean Dipole (IOD), and Indian Ocean Basin-wide (IOBW) index. The results show that the rainfall in the southern Sumatra and southern Java Islands, which face the Indian Ocean, was positively correlated with the negative IOD, whereas the rainfall in northwestern Sumatra was positively correlated with the positive IOD. In eastern Indonesia, the rainfall was positively correlated with La Niña. The PDO index was also strongly correlated with the rainfall in this region. In central Indonesia, seasonal variations due to monsoons are predominant, and the rainfall exhibited strong negative and positive correlations with the MEI and NINO.WEST, respectively, indicating that high rainfall occurred during strong La Niña episodes. The highly negative and positive correlations with the MEI and NINO.WEST, respectively, in central Indonesia led us to analyze the impacts of Indonesian seas on the rainfall in the region. Using four synoptic-scale scenarios, we investigated the relative residence time of Indonesian seawater along the pathways associated with the Pacific-Indian hydraulic head difference. The results show that when both the western Pacific and eastern Indian Oceans are warm (positive NINO.WEST and negative DMI), the rainfall intensity over central Indonesia is strongest. This increase is explained by the relationship between the residence time of Indonesian seawater and the exposure to surface evaporation: a longer exposure of Indonesian seas results in greater seawater warming and evaporation and more convection-generated cumulus clouds. Full article
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Open AccessArticle
Assessing the Influences of a Flood Diversion Project on Mitigating River Stage, Inundation Extent and Economic Loss
Water 2015, 7(4), 1731-1750; https://doi.org/10.3390/w7041731
Received: 5 February 2015 / Revised: 10 April 2015 / Accepted: 13 April 2015 / Published: 22 April 2015
Cited by 1 | Viewed by 2020 | PDF Full-text (7318 KB) | HTML Full-text | XML Full-text
Abstract
Taiwan usually suffers severe inundation disasters during typhoons and strong rainstorms, and therefore flood mitigation is considered an important issue. To assess the effect of the Yuansantze flood diversion tunnel (YFDT) on flood mitigation at the upstream reaches of the Keelung River, a [...] Read more.
Taiwan usually suffers severe inundation disasters during typhoons and strong rainstorms, and therefore flood mitigation is considered an important issue. To assess the effect of the Yuansantze flood diversion tunnel (YFDT) on flood mitigation at the upstream reaches of the Keelung River, a three-dimensional, unstructured grid, Finite-Volume, primitive equation Community Ocean Model (FVCOM) was used. The model was validated with observed data for water levels and inundation extent during different typhoon events. The simulated results show a good agreement with field measurements of water level with three historical typhoon events but underestimated the measured inundation extent with Typhoon Nari. The validated model was then applied to assess the flood mitigation and economic loss with the YFDT. The results demonstrated that the river level decreases approximately 3 m with the YFDT and that the inundation extent decreases by more than 50% in the Ruifang District with YFDT. The YDFT aims to not only mitigate hazards but also reduce economic losses. The average annual expected benefit after construction of the YFDT is approximately 184 million NTD in the Ruifang District. Full article
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Open AccessArticle
Estimating the Impact of Inflow on the Chemistry of Two Different Caldera Type Lakes Located on the Bali Island (Indonesia)
Water 2015, 7(4), 1712-1730; https://doi.org/10.3390/w7041712
Received: 9 October 2014 / Revised: 2 April 2015 / Accepted: 7 April 2015 / Published: 21 April 2015
Cited by 1 | Viewed by 2013 | PDF Full-text (6627 KB) | HTML Full-text | XML Full-text
Abstract
This paper is a preliminary attempt to assess the composition of pollutants in two different caldera lakes situated in the Indonesian Archipelago: Batur and Bratan. Both lakes are characterized by largely different physico-chemical regimes; Batur Lake is located in an area that is [...] Read more.
This paper is a preliminary attempt to assess the composition of pollutants in two different caldera lakes situated in the Indonesian Archipelago: Batur and Bratan. Both lakes are characterized by largely different physico-chemical regimes; Batur Lake is located in an area that is currently volcanically active, unlike Bratan Lake. The latter is much smaller and shallower than Batur Lake. The concentration of pollutants in the Indonesian equatorial lakes is largely unknown, and the impact of both biological and geothermal processes on their distribution requires attention. This study shows that the concentrations of cations (Na+, K+, Mg2+, Ca2+), anions (SO42−, F, Cl, Br) and trace elements (Li, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Sn, Cs, Ba, Pb, U, Be, Ag, Sb, Tl, Bi) differ greatly between both lakes. Most chemical parameters determined in volcanically influenced Batur Lake were tens to hundreds times higher than in Bratan Lake, and in the case of trace metals, the ratios of the two lakes’ concentrations reached several hundreds. This study also compared the composition and concentration levels of organic compounds in both lakes, such as fatty acids, halocarbons and esters. On the other hand, the content of organic chemicals in the lakes also results from biological activity by phytoplankton, zooplankton and bacteria. Full article
(This article belongs to the Special Issue Water Quality Control and Management)
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Open AccessArticle
Assessment of the Impacts of Climate Change on the Water Quality of a Small Deep Reservoir in a Humid-Subtropical Climatic Region
Water 2015, 7(4), 1687-1711; https://doi.org/10.3390/w7041687
Received: 5 February 2015 / Revised: 7 April 2015 / Accepted: 10 April 2015 / Published: 20 April 2015
Cited by 10 | Viewed by 2691 | PDF Full-text (5291 KB) | HTML Full-text | XML Full-text
Abstract
Surface water quality has been identified as potentially vulnerable to climate change. This study assesses the impacts of climate change on the water quality of Hsinshan Reservoir, Taiwan, through CE-QUAL-W2 simulations. The model parameters were calibrated by field data collected during 2004–2008, and [...] Read more.
Surface water quality has been identified as potentially vulnerable to climate change. This study assesses the impacts of climate change on the water quality of Hsinshan Reservoir, Taiwan, through CE-QUAL-W2 simulations. The model parameters were calibrated by field data collected during 2004–2008, and verified against observations made during 2009–2012. The projected temperature and precipitation data for the near- and long-term future were downscaled to regional and daily scales, and used to simulate the projected changes in water quality through the validated model. The simulation results were reported as probability-based cumulative distribution functions to access the impacts of climate change on water quality. The results indicated that the intensified thermal stratification caused by the rising temperature is the primary driver of water quality decline, which increases the probability of deep-layer oxygen depletion and the flux of limiting nutrients for algae growth, resulting in a higher risk of algal blooms and eutrophication. The adaptation strategies of multilevel-intake operations and increasing bottom-layer dissolved oxygen without destratification are recommended. Full article
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Open AccessArticle
Multifractal Detrended Fluctuation Analysis of Streamflow in the Yellow River Basin, China
Water 2015, 7(4), 1670-1686; https://doi.org/10.3390/w7041670
Received: 21 November 2014 / Revised: 3 April 2015 / Accepted: 8 April 2015 / Published: 17 April 2015
Cited by 22 | Viewed by 2840 | PDF Full-text (1992 KB) | HTML Full-text | XML Full-text
Abstract
Multifractal detrended fluctuation analysis (MFDFA) can provide information about inner regularity, randomness and long-range correlation of time series, promoting the knowledge of their evolution regularity. The MFDFA are applied to detect long-range correlations and multifractal behavior of streamflow series at four hydrological stations [...] Read more.
Multifractal detrended fluctuation analysis (MFDFA) can provide information about inner regularity, randomness and long-range correlation of time series, promoting the knowledge of their evolution regularity. The MFDFA are applied to detect long-range correlations and multifractal behavior of streamflow series at four hydrological stations (Toudaoguai, Longmen, Huangfu and Ganguyi) in the main channel and tributaries of the Yellow River. The results showed that there was one crossover point in the log−log curve of the fluctuation function Fq(s) versus s. The location for the crossover point is approximately one year, implying an unchanged annual periodicity within the streamflow variations. The annual periodical feature of streamflow was removed by using seasonal trend decomposition based on locally weighted regression (STL). All the decomposed streamflow series were characterized by long-term persistence in the study areas. Strong dependence of the generalized Hurst exponent h(q) on q exhibited multifractal behavior in streamflow time series at four stations in the Yellow River basin. The reduction of dependence of h(q) on q for shuffled time series showed that the multifractality of streamflow series was responsible for the correlation properties, as well as the probability density function of the streamflow series. Full article
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Open AccessArticle
Combining Choice Analysis with Stakeholder Consultation to Assess Management Options for New Zealand’s Hurunui River
Water 2015, 7(4), 1649-1669; https://doi.org/10.3390/w7041649
Received: 26 January 2015 / Revised: 2 April 2015 / Accepted: 10 April 2015 / Published: 17 April 2015
Cited by 3 | Viewed by 2123 | PDF Full-text (914 KB) | HTML Full-text | XML Full-text
Abstract
Choice experiments can be designed using information gathered in stakeholder consultation processes. Information from these two sources can be used to consider both consultation outcomes and population preferences in environmental decision making. This approach is demonstrated using a case study of New Zealand’s [...] Read more.
Choice experiments can be designed using information gathered in stakeholder consultation processes. Information from these two sources can be used to consider both consultation outcomes and population preferences in environmental decision making. This approach is demonstrated using a case study of New Zealand’s Hurunui River which has been hotly contested between those who seek to divert water and increase agricultural production and those who would like to see the river undeveloped and the natural resources in the river and catchment improved. Data from the choice experiment is used to describe and quantify the preferences of Canterbury Region residents for existing conditions (good quality in the main river and poor quality in the tributaries) and potential future land use scenarios for the catchment. Six scenarios ranging from forestry to intensive irrigation could result in deterioration or improvement. Quantitative information from the choice experiment was provided to policy makers as they considered the outcomes of the consultation process. Community stakeholders agreed on a development strategy for the Hurunui catchment that would improve water quality in the tributaries and maintain quality in the main river. Results from the choice experiment support this approach. Willingness to pay for improvements in the main river was limited but residents would require substantial compensation before they would accept a decline in water quality in the main river or in the tributaries. Full article
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Open AccessArticle
Active Tectonics Revealed by River Profiles along the Puqu Fault
Water 2015, 7(4), 1628-1648; https://doi.org/10.3390/w7041628
Received: 12 January 2015 / Revised: 24 March 2015 / Accepted: 6 April 2015 / Published: 17 April 2015
Cited by 2 | Viewed by 2093 | PDF Full-text (4635 KB) | HTML Full-text | XML Full-text
Abstract
The Puqu Fault is situated in Southern Tibet. It is influenced by the eastward extrusion of Northern Tibet and carries the clockwise rotation followed by the southward extrusion. Thus, the Puqu Fault is bounded by the principal dynamic zones and the tectonic evolution [...] Read more.
The Puqu Fault is situated in Southern Tibet. It is influenced by the eastward extrusion of Northern Tibet and carries the clockwise rotation followed by the southward extrusion. Thus, the Puqu Fault is bounded by the principal dynamic zones and the tectonic evolution remains active alongside. This study intends to understand the tectonic activity in the Puqu Fault Region from the river profiles obtained from the remotely sensed satellite imagery. A medium resolution Digital Elevation Model (DEM, 20 m) was generated from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo pair of images and the stream network in this region was extracted from this DEM. The indices of slope and drainage area were subsequently calculated from this ASTER DEM. Based on the stream power law, the area-slope plots of the streams were delineated to derive the indices of channel concavity and steepness, which are closely related to tectonic activity. The results show the active tectonics varying significantly along the Puqu Fault, although the potential influence of glaciations may exist. These results are expected to be useful for a better understanding of tectonic evolution in Southeastern Tibet. Full article
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Open AccessArticle
A Structurally Simplified Hybrid Model of Genetic Algorithm and Support Vector Machine for Prediction of Chlorophyll a in Reservoirs
Water 2015, 7(4), 1610-1627; https://doi.org/10.3390/w7041610
Received: 13 January 2015 / Revised: 21 March 2015 / Accepted: 3 April 2015 / Published: 16 April 2015
Cited by 7 | Viewed by 2441 | PDF Full-text (1560 KB) | HTML Full-text | XML Full-text
Abstract
With decreasing water availability as a result of climate change and human activities, analysis of the influential factors and variation trends of chlorophyll a has become important to prevent reservoir eutrophication and ensure water supply safety. In this paper, a structurally simplified hybrid [...] Read more.
With decreasing water availability as a result of climate change and human activities, analysis of the influential factors and variation trends of chlorophyll a has become important to prevent reservoir eutrophication and ensure water supply safety. In this paper, a structurally simplified hybrid model of the genetic algorithm (GA) and the support vector machine (SVM) was developed for the prediction of monthly concentration of chlorophyll a in the Miyun Reservoir of northern China over the period from 2000 to 2010. Based on the influence factor analysis, the four most relevant influence factors of chlorophyll a (i.e., total phosphorus, total nitrogen, permanganate index, and reservoir storage) were extracted using the method of feature selection with the GA, which simplified the model structure, making it more practical and efficient for environmental management. The results showed that the developed simplified GA-SVM model could solve nonlinear problems of complex system, and was suitable for the simulation and prediction of chlorophyll a with better performance in accuracy and efficiency in the Miyun Reservoir. Full article
(This article belongs to the Special Issue Hydro-Ecological Modeling) Printed Edition available
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Open AccessArticle
Laboratory Studies on Granular Filters and Their Relationship to Geotextiles for Stormwater Pollutant Reduction
Water 2015, 7(4), 1595-1609; https://doi.org/10.3390/w7041595
Received: 28 November 2014 / Revised: 1 April 2015 / Accepted: 2 April 2015 / Published: 15 April 2015
Cited by 5 | Viewed by 2833 | PDF Full-text (1091 KB) | HTML Full-text | XML Full-text
Abstract
Applications of geotextiles within tertiary stormwater treatment systems and for stormwater infiltration can provide a substrate for biofilm formation, enabling biological treatment of contaminants. Geotextiles can serve as an efficient part of stormwater filtration within the urban water environment. The project assessed the [...] Read more.
Applications of geotextiles within tertiary stormwater treatment systems and for stormwater infiltration can provide a substrate for biofilm formation, enabling biological treatment of contaminants. Geotextiles can serve as an efficient part of stormwater filtration within the urban water environment. The project assessed the applications of three experimental granular filters as a sustainable urban drainage system (SUDS) for the decomposition of organic pollutant loading present in stormwater. The three filter rigs were packed with alternating layers of filter media consisting of gravel, pea gravel, sand and either a single, double or no layer of geotextile membrane. A nonwoven geotextile was layered within the filter media. The hydraulic loading capacity for the three filters matched that commonly used with conventional sand filters systems. Water quality parameters were quantified by measuring suspended solids, chemical oxygen demand, dissolved oxygen, pH, nitrate-nitrogen, and phosphate concentrations. It was found that Filter Rig No. 3 (upper and lower geotextile membrane) and Filter Rig No. 2 (single geotextile membrane) had a significant statistical difference in treatment performance from Filter Rig No. 1 (no geotextile membrane). Full article
(This article belongs to the Special Issue Water Quality Control and Management)
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Open AccessReview
Hydrometeorological Research in South Africa: A Review
Water 2015, 7(4), 1580-1594; https://doi.org/10.3390/w7041580
Received: 12 December 2014 / Revised: 12 March 2015 / Accepted: 19 March 2015 / Published: 15 April 2015
Cited by 3 | Viewed by 2179 | PDF Full-text (494 KB) | HTML Full-text | XML Full-text
Abstract
Water resources, particularly in arid and semi-arid regions of the world are of great concern, as they are closely linked to the wellbeing of humankind. Sophisticated hydrological prediction tools are required to assess climatic and hydrometeorological conditions, as they impact the sustainability of [...] Read more.
Water resources, particularly in arid and semi-arid regions of the world are of great concern, as they are closely linked to the wellbeing of humankind. Sophisticated hydrological prediction tools are required to assess climatic and hydrometeorological conditions, as they impact the sustainability of water resources as well as water availability. Research and data collection activities from multi-hydrometeorological sensors (e.g., gauges, radars, satellites) form the basis for quantifying the impact of extreme episodes along the hydrologic phases that manifest in terms of the magnitude, duration and frequency of floods, droughts and other hydrometeorological hazards that affect water resources management. A number of hydrometeorological research activities have been reported in the literature by various researchers and research groups globally. This contribution presents (a) a review of the hydrometeorology resource landscape in South Africa; (b) an analysis of the hydrometeorology services and products in South Africa; (c) a review of the hydrometeorological research that has been conducted in South Africa for the last four decades; and (d) highlights on some of the challenges facing the sustained advancement of research in hydrometeorology in South Africa. Full article
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Open AccessArticle
Chemical Analysis of Wastewater from Unconventional Drilling Operations
Water 2015, 7(4), 1568-1579; https://doi.org/10.3390/w7041568
Received: 6 February 2015 / Revised: 3 April 2015 / Accepted: 8 April 2015 / Published: 15 April 2015
Cited by 41 | Viewed by 4130 | PDF Full-text (367 KB) | HTML Full-text | XML Full-text
Abstract
Trillions of liters of wastewater from oil and gas extraction are generated annually in the US. The contribution from unconventional drilling operations (UDO), such as hydraulic fracturing, to this volume will likely continue to increase in the foreseeable future. The chemical content of [...] Read more.
Trillions of liters of wastewater from oil and gas extraction are generated annually in the US. The contribution from unconventional drilling operations (UDO), such as hydraulic fracturing, to this volume will likely continue to increase in the foreseeable future. The chemical content of wastewater from UDO varies with region, operator, and elapsed time after production begins. Detailed chemical analyses may be used to determine its content, select appropriate treatment options, and identify its source in cases of environmental contamination. In this study, one wastewater sample each from direct effluent, a disposal well, and a waste pit, all in West Texas, were analyzed by gas chromatography-mass spectrometry, inductively coupled plasma-optical emission spectroscopy, high performance liquid chromatography-high resolution mass spectrometry, high performance ion chromatography, total organic carbon/total nitrogen analysis, and pH and conductivity analysis. Several compounds known to compose hydraulic fracturing fluid were detected among two of the wastewater samples including 2-butoxyethanol, alkyl amines, and cocamide diethanolamines, toluene, and o-xylene. Due both to its quantity and quality, proper management of wastewater from UDO will be essential. Full article
(This article belongs to the Special Issue Water Quality Control and Management)
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Open AccessArticle
Combined Impacts of Medium Term Socio-Economic Changes and Climate Change on Water Resources in a Managed Mediterranean Catchment
Water 2015, 7(4), 1538-1567; https://doi.org/10.3390/w7041538
Received: 2 February 2015 / Revised: 17 March 2015 / Accepted: 27 March 2015 / Published: 10 April 2015
Cited by 7 | Viewed by 2614 | PDF Full-text (2489 KB) | HTML Full-text | XML Full-text
Abstract
Climate projections agree on a dryer and warmer future for the Mediterranean. Consequently, the region is likely to face serious problems regarding water availability and quality in the future. We investigated potential climate change impacts, alone (for three scenario periods) and in combination [...] Read more.
Climate projections agree on a dryer and warmer future for the Mediterranean. Consequently, the region is likely to face serious problems regarding water availability and quality in the future. We investigated potential climate change impacts, alone (for three scenario periods) and in combination with four socio-economic scenarios (for the near future) on water resources in a Mediterranean catchment, whose economy relies on irrigated agriculture and tourism. For that, the Soil and Water Integrated Model (SWIM) was applied to the drainage area of the Mar Menor coastal lagoon, using a set of 15 climate scenarios and different land use maps and management settings. We assessed the long-term average seasonal and annual changes in generated runoff, groundwater recharge and actual evapotranspiration in the catchment, as well as on water inflow and nutrients input to the lagoon. The projected average annual changes in precipitation are small for the first scenario period, and so are the simulated impacts on all investigated components, on average. The negative trend of potential climate change impacts on water resources (i.e., decrease in all analyzed components) becomes pronounced in the second and third scenario periods. The applied socio-economic scenarios intensify, reduce or even reverse the climate-induced impacts, depending on the assumed land use and management changes. Full article
(This article belongs to the Special Issue Hydro-Ecological Modeling) Printed Edition available
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Open AccessArticle
Evaluating the Sources and Fate of Nitrate in the Alluvial Aquifers in the Shijiazhuang Rural and Suburban Area, China: Hydrochemical and Multi-Isotopic Approaches
Water 2015, 7(4), 1515-1537; https://doi.org/10.3390/w7041515
Received: 7 December 2014 / Revised: 26 March 2015 / Accepted: 27 March 2015 / Published: 9 April 2015
Cited by 5 | Viewed by 2228 | PDF Full-text (770 KB) | HTML Full-text | XML Full-text
Abstract
The identification of the sources and fate of NO\(_{3}^{-}\) contaminants is important to protect the water quality of aquifer systems. In this study, NO\(_{3}^{-}\) contaminated groundwater from the drinking water wells in the Shijiazhuang area, China, was chemically (NO\(_{3}^{-}\)/Cl\(^{\rm{{-}}}\) ratio) and isotopically (\(δ\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\), [...] Read more.
The identification of the sources and fate of NO\(_{3}^{-}\) contaminants is important to protect the water quality of aquifer systems. In this study, NO\(_{3}^{-}\) contaminated groundwater from the drinking water wells in the Shijiazhuang area, China, was chemically (NO\(_{3}^{-}\)/Cl\(^{\rm{{-}}}\) ratio) and isotopically (\(δ\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\), \(\delta\)\(^{\rm{18}}\)O\(_{\rm{NO3}}\) and \(\delta\)\(^{\rm{13}}\)C\(_{\rm{DOC}}\); \(\delta\)\(^{\rm{2}}\)H\(_{\rm{H2O}}\), \(\delta\)\(^{\rm{18}}\)O\(_{\rm{H2O}}\)) characterized to identify the sources of NO\(_{3}^{-}\) and address subsequent biogeochemical processes. The positive correlations between dominant anions and cations suggested that the dissolution of calcium carbonate and gypsum minerals was the most effective process in the groundwater. Elevated concentrations of NO\(_{3}^{-}\), Cl\(^{\rm{{-}}}\) and Mg\(^{\rm{2+}}\) could be related to the wastewater irrigation and usage of fertilizers. The natural water in the study area originated primarily from precipitation and experienced a limited extent of evaporation, as demonstrated by measurements of \(\delta\)\(^{\rm{2}}\)H\(_{\rm{H2O}}\) and \(\delta\)\(^{\rm{18}}\)O\(_{\rm{H2O}}\). A cross-plot of \(\delta\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\) vs. \(\delta\)\(^{\rm{18}}\)O\(_{\rm{NO3}}\) gave an enrichment of the 15N isotope relative to the 18O isotope by a factor of 2. A further insight into the denitrification process was obtained by the synergistic changes in \(\delta\)\(^{\rm{13}}\)C\(_{\rm{DOC}}\) and \(\delta\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\) values, confirming that a low extent of denitrification occurred. Nitrification processes were evaluated by means of \(\delta\)\(^{\rm{18}}\)O\(_{\rm{NO3}}\) and \(\delta\)\(^{\rm{18}}\)O\(_{\rm{H2O}}\). The initial \(\delta\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\) value(s) of the NO\(_{3}^{-}\) source(s) were roughly estimated between 2‰ and 5‰. Based on the level of natural NO\(_{3}^{-}\), anthropogenic activities were considered the main reason for the elevated NO\(_{3}^{-}\) concentration of the shallow groundwater. NH\(_{4}^{+}\) fertilizers were the major source of NO\(_{3}^{-}\) in the non-wastewater irrigated area, while wastewater was regarded as the primary source of NO\(_{3}^{-}\) in the wastewater-irrigated area. A low content of NO\(_{3}^{-}\) in deep groundwater might mainly be influenced by precipitation and soil organic N that was involved in denitrification reactions. Some of the deep groundwater samples could have been contaminated by wastewater. The mixing process of multiple NO\(_{3}^{-}\) sources was identified as another important factor affecting the NO\(_{3}^{-}\) concentration of the groundwater in the study area. The combined use of \(\delta\)\(^{\rm{15}}\)N\(_{\rm{NO3}}\), \(\delta\)\(^{\rm{18}}\)O\(_{\rm{NO3}}\) and \(\delta\)\(^{\rm{13}}\)C\(_{\rm{DOC}}\) results and hydrochemical data (NO\(_{3}^{-}\)/Cl\(^{\rm{{-}}}\) ratios) gives an insight into the mixing effect of different NO\(_{3}^{-}\) sources and processes affecting NO\(_{3}^{-}\) concentration under conditions of intensive land-use activities. Full article
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Open AccessArticle
Rethinking Sustainability, Scaling Up, and Enabling Environment: A Framework for Their Implementation in Drinking Water Supply
Water 2015, 7(4), 1497-1514; https://doi.org/10.3390/w7041497
Received: 31 December 2014 / Revised: 3 March 2015 / Accepted: 18 March 2015 / Published: 3 April 2015
Cited by 14 | Viewed by 5049 | PDF Full-text (631 KB) | HTML Full-text | XML Full-text
Abstract
The terms sustainability, scaling up, and enabling environment are inconsistently used in implementing water supply projects. To clarify these terms we develop a framework based on Normalization Process Theory, and apply the framework to a hypothetical water supply project in schools. The resulting [...] Read more.
The terms sustainability, scaling up, and enabling environment are inconsistently used in implementing water supply projects. To clarify these terms we develop a framework based on Normalization Process Theory, and apply the framework to a hypothetical water supply project in schools. The resulting framework provides guidance on how these terms could be implemented and analyzed in water supply projects. We conclude that effective use of the terms sustainability, scaling up, and enabling environment would focus on purpose, process, and perspective. This is the first known attempt to analyze the implementation of the three terms together in the context of water supply services. Full article
(This article belongs to the Special Issue Water Treatment and Human Health)
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Open AccessArticle
Aluminum-Based Water Treatment Residue Reuse for Phosphorus Removal
Water 2015, 7(4), 1480-1496; https://doi.org/10.3390/w7041480
Received: 16 January 2015 / Revised: 9 March 2015 / Accepted: 27 March 2015 / Published: 1 April 2015
Cited by 8 | Viewed by 2259 | PDF Full-text (375 KB) | HTML Full-text | XML Full-text
Abstract
Aluminum-based water treatment residue (Al-WTR) generated during the drinking water treatment process is a readily available recycled material with high phosphorus (P) adsorption capacity. The P adsorption capacity of Al-WTR generated from Singapore’s water treatment plant was evaluated with reference to particle size [...] Read more.
Aluminum-based water treatment residue (Al-WTR) generated during the drinking water treatment process is a readily available recycled material with high phosphorus (P) adsorption capacity. The P adsorption capacity of Al-WTR generated from Singapore’s water treatment plant was evaluated with reference to particle size range, adsorption pH and temperature. Column tests, with WTR amendments in sand with and without compost, were used to simulate the bioretention systems. The adsorption rate decreased with increasing WTR sizes. Highest P adsorption capacity, 15.57 mg PO43-P/g WTR, was achieved using fine WTR particles (>50% particles at less than 0.30 mm). At pH 4, the contact time required to reduce effluent P concentration to below the detectable range was half compared with pH 7 and 9. The adsorption rate observed at 40 ± 2 °C was 21% higher compared with that at 30 ± 2 °C. Soil mixes amended with 10% WTR and compost were able to maintain consistently high (90%) total phosphorus (TP) removal efficiency at a TP load up to 6.45 g/m3. In contrast, TP removal efficiencies associated with columns without WTR amendment decreased to less than 45% as the TP load increased beyond 4.5 g/m3. The results showed that WTR application is beneficial for enhanced TP removal in bioretention systems. Full article
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Open AccessReview
Urban Water Tariffs in Spain: What Needs to Be Done?
Water 2015, 7(4), 1456-1479; https://doi.org/10.3390/w7041456
Received: 19 January 2015 / Revised: 8 March 2015 / Accepted: 9 March 2015 / Published: 31 March 2015
Cited by 14 | Viewed by 4627 | PDF Full-text (1186 KB) | HTML Full-text | XML Full-text
Abstract
Recently, in the context of the Integrated Water Resources Management, demand policies are playing a more important role as opposed to traditional supply policies based on the construction of large hydraulic infrastructures. In this new context, water tariffs have become an important tool [...] Read more.
Recently, in the context of the Integrated Water Resources Management, demand policies are playing a more important role as opposed to traditional supply policies based on the construction of large hydraulic infrastructures. In this new context, water tariffs have become an important tool in achieving economic efficiency, environmental sustainability, and social equity. This paper reviews the situation of urban water tariffs in Spain, a country subject to high water stress. It analyzes the capacity of urban water tariffs to recover service costs and to promote efficiency, sustainability, affordability, and equity. Although it has made significant progress in recent years, the Spanish urban water tariff system still faces many challenges. Many of these challenges would be better addressed by a national independent regulatory body. Full article
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Open AccessArticle
Urban Flood Mapping Based on Unmanned Aerial Vehicle Remote Sensing and Random Forest Classifier—A Case of Yuyao, China
Water 2015, 7(4), 1437-1455; https://doi.org/10.3390/w7041437
Received: 30 November 2014 / Revised: 13 March 2015 / Accepted: 25 March 2015 / Published: 31 March 2015
Cited by 54 | Viewed by 4531 | PDF Full-text (11645 KB) | HTML Full-text | XML Full-text
Abstract
Flooding is a severe natural hazard, which poses a great threat to human life and property, especially in densely-populated urban areas. As one of the fastest developing fields in remote sensing applications, an unmanned aerial vehicle (UAV) can provide high-resolution data with a [...] Read more.
Flooding is a severe natural hazard, which poses a great threat to human life and property, especially in densely-populated urban areas. As one of the fastest developing fields in remote sensing applications, an unmanned aerial vehicle (UAV) can provide high-resolution data with a great potential for fast and accurate detection of inundated areas under complex urban landscapes. In this research, optical imagery was acquired by a mini-UAV to monitor the serious urban waterlogging in Yuyao, China. Texture features derived from gray-level co-occurrence matrix were included to increase the separability of different ground objects. A Random Forest classifier, consisting of 200 decision trees, was used to extract flooded areas in the spectral-textural feature space. Confusion matrix was used to assess the accuracy of the proposed method. Results indicated the following: (1) Random Forest showed good performance in urban flood mapping with an overall accuracy of 87.3% and a Kappa coefficient of 0.746; (2) the inclusion of texture features improved classification accuracy significantly; (3) Random Forest outperformed maximum likelihood and artificial neural network, and showed a similar performance to support vector machine. The results demonstrate that UAV can provide an ideal platform for urban flood monitoring and the proposed method shows great capability for the accurate extraction of inundated areas. Full article
(This article belongs to the Special Issue Advances in Remote Sensing of Flooding)
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Open AccessArticle
Performance Evaluation for a Contamination Detection Method Using Multiple Water Quality Sensors in an Early Warning System
Water 2015, 7(4), 1422-1436; https://doi.org/10.3390/w7041422
Received: 13 January 2015 / Revised: 2 March 2015 / Accepted: 24 March 2015 / Published: 30 March 2015
Cited by 7 | Viewed by 2641 | PDF Full-text (284 KB) | HTML Full-text | XML Full-text
Abstract
In this approach, a method utilizing data series from multivariate parameters to detect contaminant events is discussed and evaluated. Eight water quality sensors (pH, turbidity, conductivity, temperature, oxidation reduction potential, UV-254, nitrate and phosphate) are used in this study and the most commonly [...] Read more.
In this approach, a method utilizing data series from multivariate parameters to detect contaminant events is discussed and evaluated. Eight water quality sensors (pH, turbidity, conductivity, temperature, oxidation reduction potential, UV-254, nitrate and phosphate) are used in this study and the most commonly used herbicide, glyphosate, is selected as the test contaminant. Variations of all parameters are recorded in real time at different concentrations. The results from the experiment and analysis show that the proposed method with suitable optimization can detect a glyphosate contamination less than 5 min after the introduction of the contaminant using responses from online water quality sensors. The average true positive rate is 95.5%. The study also discusses the impact of the number of sensors on detection performance. The results show that if the number of sensors is reduced from 8 to 5, the true positive rate performance is still good. This indicates that the method is flexible and can be applied using a smaller number of sensors to reduce monitoring costs. Full article
(This article belongs to the Special Issue Water Quality Control and Management)
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Open AccessArticle
Rainwater Harvesting for Small-Holder Horticulture in Namibia: Design of Garden Variants and Assessment of Climate Change Impacts and Adaptation
Water 2015, 7(4), 1402-1421; https://doi.org/10.3390/w7041402
Received: 20 December 2014 / Revised: 27 February 2015 / Accepted: 5 March 2015 / Published: 30 March 2015
Cited by 6 | Viewed by 4121 | PDF Full-text (1204 KB) | HTML Full-text | XML Full-text
Abstract
The design of rainwater harvesting based gardens requires considering current climate but also climate change during the lifespan of the facility. The goal of this study is to present an approach for designing garden variants that can be safely supplied with harvested rainwater, [...] Read more.
The design of rainwater harvesting based gardens requires considering current climate but also climate change during the lifespan of the facility. The goal of this study is to present an approach for designing garden variants that can be safely supplied with harvested rainwater, taking into account climate change and adaptation measures. In addition, the study presents a methodology to quantify the effects of climate change on rainwater harvesting based gardening. Results of the study may not be accurate due to the assumptions made for climate projections and may need to be further refined. We used a tank flow model and an irrigation water model. Then we established three simple climate scenarios and analyzed the impact of climate change on harvested rain and horticulture production for a semi-arid region in northern Namibia. In the two climate scenarios with decreased precipitation and medium/high temperature increase; adaptation measures are required to avoid substantial decreases in horticulture production. The study found that the most promising adaptation measures to sustain yields and revenues are a more water efficient garden variant and an enlargement of the roof size. The proposed measures can partly or completely compensate the negative impacts of climate change. Full article
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Open AccessArticle
Locating Leaks with TrustRank Algorithm Support
Water 2015, 7(4), 1378-1401; https://doi.org/10.3390/w7041378
Received: 24 December 2014 / Revised: 26 February 2015 / Accepted: 16 March 2015 / Published: 27 March 2015
Cited by 7 | Viewed by 2140 | PDF Full-text (3741 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a methodology to quantify and to locate leaks. The original contribution is the use of a tool based on the TrustRank algorithm for the selection of nodes for pressure monitoring. The results from these methodologies presented here are: (I) A [...] Read more.
This paper presents a methodology to quantify and to locate leaks. The original contribution is the use of a tool based on the TrustRank algorithm for the selection of nodes for pressure monitoring. The results from these methodologies presented here are: (I) A sensitivity analysis of the number of pressure transducers on the quality of the final solution; (II) A reduction of the number of pipes to be inspected; and (III) A focus on the problematic pipes which allows a better office planning of the inspection works to perform atthe field. To obtain these results, a methodology for the identification of probable leaky pipes and an estimate of their leakage flows is also presented. The potential of the methodology is illustrated with several case studies, considering different levels of water losses and different sets of pressure monitoring nodes. The results are discussed and the solutions obtained show the benefits of the developed methodologies. Full article
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Open AccessArticle
Predicting Multiple Functions of Sustainable Flood Retention Basins under Uncertainty via Multi-Instance Multi-Label Learning
Water 2015, 7(4), 1359-1377; https://doi.org/10.3390/w7041359
Received: 16 December 2014 / Revised: 12 March 2015 / Accepted: 13 March 2015 / Published: 26 March 2015
Cited by 2 | Viewed by 2323 | PDF Full-text (2919 KB) | HTML Full-text | XML Full-text
Abstract
The ambiguity of diverse functions of sustainable flood retention basins (SFRBs) may lead to conflict and risk in water resources planning and management. How can someone provide an intuitive yet efficient strategy to uncover and distinguish the multiple potential functions of SFRBs under [...] Read more.
The ambiguity of diverse functions of sustainable flood retention basins (SFRBs) may lead to conflict and risk in water resources planning and management. How can someone provide an intuitive yet efficient strategy to uncover and distinguish the multiple potential functions of SFRBs under uncertainty? In this study, by exploiting both input and output uncertainties of SFRBs, the authors developed a new data-driven framework to automatically predict the multiple functions of SFRBs by using multi-instance multi-label (MIML) learning. A total of 372 sustainable flood retention basins, characterized by 40 variables associated with confidence levels, were surveyed in Scotland, UK. A Gaussian model with Monte Carlo sampling was used to capture the variability of variables (i.e., input uncertainty), and the MIML-support vector machine (SVM) algorithm was subsequently applied to predict the potential functions of SFRBs that have not yet been assessed, allowing for one basin belonging to different types (i.e., output uncertainty). Experiments demonstrated that the proposed approach enables effective automatic prediction of the potential functions of SFRBs (e.g., accuracy >93%). The findings suggest that the functional uncertainty of SFRBs under investigation can be better assessed in a more comprehensive and cost-effective way, and the proposed data-driven approach provides a promising method of doing so for water resources management. Full article
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Open AccessArticle
Impacts of Urbanization on River Systems in the Taihu Region, China
Water 2015, 7(4), 1340-1358; https://doi.org/10.3390/w7041340
Received: 9 October 2014 / Revised: 4 December 2014 / Accepted: 17 March 2015 / Published: 26 March 2015
Cited by 12 | Viewed by 2424 | PDF Full-text (3726 KB) | HTML Full-text | XML Full-text
Abstract
River systems are valuable to human beings; meanwhile, they are intensively influenced by human activities, especially urbanization. In this study, based on the data derived from topographic maps and remote sensing images, the temporal and spatial change of river system geomorphology in the [...] Read more.
River systems are valuable to human beings; meanwhile, they are intensively influenced by human activities, especially urbanization. In this study, based on the data derived from topographic maps and remote sensing images, the temporal and spatial change of river system geomorphology in the Taihu Region over the past 50 years was investigated in conjunction with urbanization. Results demonstrated that the number of river systems decreased drastically, that the morphology of river channels changed into wider and straighter and that the structure of river network tended to simplify in the Taihu Region in recent 50 years. Meanwhile, the changes in river density, the water surface ratio, the river development coefficient, the main river area length ratio and the box dimension in the rapid urbanization period were much greater than those in the slow urbanization period, but the decrease of river sinuosity in the slow urbanization period was more intense. Moreover, the spatial differences of the changes in the river development coefficient were the largest, and the changes in the river indicators in the low-urbanized regions were the most intense. In addition, the changes in the water surface ratio had the closest correlation with urbanization, and the relational degrees between population urbanization and the changes in river systems were the largest. The results can provide a reliable basis to determine reasonable management and conservation strategies of river systems in the Taihu Region. Full article
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Open AccessCommunication
Can Low-Resolution Airborne Laser Scanning Data Be Used to Model Stream Rating Curves?
Water 2015, 7(4), 1324-1339; https://doi.org/10.3390/w7041324
Received: 8 December 2014 / Revised: 25 February 2015 / Accepted: 16 March 2015 / Published: 24 March 2015
Cited by 4 | Viewed by 4632 | PDF Full-text (954 KB) | HTML Full-text | XML Full-text
Abstract
This pilot study explores the potential of using low-resolution (0.2 points/m2) airborne laser scanning (ALS)-derived elevation data to model stream rating curves. Rating curves, which allow the functional translation of stream water depth into discharge, making them integral to water resource [...] Read more.
This pilot study explores the potential of using low-resolution (0.2 points/m2) airborne laser scanning (ALS)-derived elevation data to model stream rating curves. Rating curves, which allow the functional translation of stream water depth into discharge, making them integral to water resource monitoring efforts, were modeled using a physics-based approach that captures basic geometric measurements to establish flow resistance due to implicit channel roughness. We tested synthetically thinned high-resolution (more than 2 points/m2) ALS data as a proxy for low-resolution data at a point density equivalent to that obtained within most national-scale ALS strategies. Our results show that the errors incurred due to the effect of low-resolution versus high-resolution ALS data were less than those due to flow measurement and empirical rating curve fitting uncertainties. As such, although there likely are scale and technical limitations to consider, it is theoretically possible to generate rating curves in a river network from ALS data of the resolution anticipated within national-scale ALS schemes (at least for rivers with relatively simple geometries). This is promising, since generating rating curves from ALS scans would greatly enhance our ability to monitor streamflow by simplifying the overall effort required. Full article
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