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Water, Volume 11, Issue 10 (October 2019) – 243 articles

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Cover Story (view full-size image) Looming water scarcity due to the lacking and pollution of water resources is one of the most [...] Read more.
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Open AccessArticle
Future Response of the Wadden Sea Tidal Basins to Relative Sea-Level rise—An Aggregated Modelling Approach
Water 2019, 11(10), 2198; https://doi.org/10.3390/w11102198 - 22 Oct 2019
Cited by 2 | Viewed by 969
Abstract
Climate change, and especially the associated acceleration of sea-level rise, forms a serious threat to the Wadden Sea. The Wadden Sea contains the world’s largest coherent intertidal flat area and it is known that these flats can drown when the rate of sea-level [...] Read more.
Climate change, and especially the associated acceleration of sea-level rise, forms a serious threat to the Wadden Sea. The Wadden Sea contains the world’s largest coherent intertidal flat area and it is known that these flats can drown when the rate of sea-level rise exceeds a critical limit. As a result, the intertidal flats would then be permanently inundated, seriously affecting the ecological functioning of the system. The determination of this critical limit and the modelling of the transient process of how a tidal basin responds to accelerated sea-level rise is of critical importance. In this contribution we revisit the modelling of the response of the Wadden Sea tidal basins to sea-level rise using a basin scale morphological model (aggregated scale morphological interaction between tidal basin and adjacent coast, ASMITA). Analysis using this aggregated scale model shows that the critical rate of sea-level rise is not merely influenced by the morphological equilibrium and the morphological time scale, but also depends on the grain size distribution of sediment in the tidal inlet system. As sea-level rises, there is a lag in the morphological response, which means that the basin will be deeper than the systems morphological equilibrium. However, so long as the rate of sea-level rise is constant and below a critical limit, this offset becomes constant and a dynamic equilibrium is established. This equilibrium deviation as well as the time needed to achieve the dynamic equilibrium increase non-linearly with increasing rates of sea-level rise. As a result, the response of a tidal basin to relatively fast sea-level rise is similar, no matter if the sea-level rise rate is just below, equal or above the critical limit. A tidal basin will experience a long process of ‘drowning’ when sea-level rise rate exceeds about 80% of the critical limit. The insights from the present study can be used to improve morphodynamic modelling of tidal basin response to accelerating sea-level rise and are useful for sustainable management of tidal inlet systems. Full article
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Open AccessArticle
Flow Depths and Velocities across a Smooth Dike Crest
Water 2019, 11(10), 2197; https://doi.org/10.3390/w11102197 - 22 Oct 2019
Cited by 1 | Viewed by 828
Abstract
This contribution proposes a systematic analysis of the overtopping process at dikes, focused on the statistical description of the extreme flow characteristics across the dike crest. The specific objective of the analysis is the investigation of structures subjected to high run-up levels and [...] Read more.
This contribution proposes a systematic analysis of the overtopping process at dikes, focused on the statistical description of the extreme flow characteristics across the dike crest. The specific objective of the analysis is the investigation of structures subjected to high run-up levels and low freeboards, under severe or extreme conditions that are likely to occur in the future due to climate change. The adopted methodology is based on the collection of new experimental and numerical tests of wave overtopping at smooth dikes at various crest levels. The reliability of the new data is checked in terms of average overtopping discharge and wave reflection coefficient, against consolidated predicting methods from the literature. An update and refitting of the existing formulae for the prediction of the extreme flow depths and velocities at the dike off-shore edge is proposed based on the experimental and numerical outcomes. The dynamics of the overtopping flow propagation along the dike crest under breaking and non-breaking waves, in emerged and submerged conditions, is investigated. Guidelines to update the state-of-the-art formulae for a more cautious estimation of the water depths and the velocities of propagation of the flow in the landward area are provided. Full article
(This article belongs to the Special Issue Interaction between Waves and Maritime Structures)
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Open AccessArticle
Mapping Flood-Related Mortality in the Mediterranean Basin. Results from the MEFF v2.0 DB
Water 2019, 11(10), 2196; https://doi.org/10.3390/w11102196 - 22 Oct 2019
Cited by 7 | Viewed by 1139
Abstract
Recent events in Western Attica in Greece (24 deaths in November 2017), in the Balearic Islands (13 deaths in October 2018), and in southern France (15 deaths in October 2018) show that flood-related mortality remains a major concern in Mediterranean countries facing flash [...] Read more.
Recent events in Western Attica in Greece (24 deaths in November 2017), in the Balearic Islands (13 deaths in October 2018), and in southern France (15 deaths in October 2018) show that flood-related mortality remains a major concern in Mediterranean countries facing flash floods. Over the past several years, many initiatives have arisen to create databases on flood-related mortality. An international initiative started in 2011 pooling regional and national databases on flood mortality from region and/or countries bordering the Mediterranean Sea. The MEditerranean Flood Fatality Database (MEFF DB) brings together, in 2018, six Mediterranean regions/countries: Catalonia (Spain), Balearic Islands (Spain), Southern France, Calabria (Italy), Greece, and Turkey, and covers the period 1980–2018. MEFF DB is on progress and, every year, new data are included, but for this study, we kept only the preliminary data that were geolocated and validated on 31st of December 2018. This research introduces a new step in the analysis of flood-related mortality and follows the statistical description of the MEFF DB already published. The goals of this paper are to draw the spatial distribution of flood mortality through a geographical information system (GIS) at different spatial scales: country, NUTS 3 (Nomenclature of Territorial Units for Statistics. Level 3) regions, catchment areas, and grid. A fatality rate (F: number of deaths/year/million of inhabitants) is created to help this analysis. Then, we try to relate mortality to basic (human or physical) drivers such as population density, rainfall seasonality, or rainfall frequency across the Mediterranean Basin. The mapping of F shows a negative mortality gradient between the western and the eastern parts of the Mediterranean Sea. The south of France appears to be the most affected region. The maps also highlight the seasonality of flood-related deaths with the same west–east gradient. It confirms that flood mortality follows the climatological seasonal patterns across the Mediterranean Basin. Flood-related fatalities mainly occur during the early fall season in the western part of the Mediterranean area, while the Easter Basin is affected later, in November or during the winter season. Eastern Turkey introduces another pattern, as mortality is more severe in summer. Mortality maps are then compared with factors that potentially contribute to the occurrence of flood fatalities, such as precipitation intensity (rainfall hazard), to explain geographical differences in the fatality rate. The density of a fatal event is correlated to the population density and the rainfall frequency. Conversely, the average number of deaths per event depends on other factors such as prevention or crisis management. Full article
(This article belongs to the Special Issue Damaging Hydrogeological Events)
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Open AccessArticle
Computationally Efficient Solution of a 2D Diffusive Wave Equation Used for Flood Inundation Problems
Water 2019, 11(10), 2195; https://doi.org/10.3390/w11102195 - 22 Oct 2019
Cited by 1 | Viewed by 580
Abstract
This paper presents a study dealing with increasing the computational efficiency in modeling floodplain inundation using a two-dimensional diffusive wave equation. To this end, the domain decomposition technique was used. The resulting one-dimensional diffusion equations were approximated in space with the modified finite [...] Read more.
This paper presents a study dealing with increasing the computational efficiency in modeling floodplain inundation using a two-dimensional diffusive wave equation. To this end, the domain decomposition technique was used. The resulting one-dimensional diffusion equations were approximated in space with the modified finite element scheme, whereas time integration was carried out using the implicit two-level scheme. The proposed algorithm of the solution minimizes the numerical errors and is unconditionally stable. Consequently, it is possible to perform computations with a significantly greater time step than in the case of the explicit scheme. An additional efficiency improvement was achieved using the symmetry of the tridiagonal matrix of the arising system of nonlinear equations, due to the application of the parallelization strategy. The computational experiments showed that the proposed parallel implementation of the implicit scheme is very effective, at about two orders of magnitude with regard to computational time, in comparison with the explicit one. Full article
(This article belongs to the Section Hydrology and Hydrogeology)
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Open AccessArticle
Investigation on the Effect of Structural Parameters on Cavitation Characteristics for the Venturi Tube Using the CFD Method
Water 2019, 11(10), 2194; https://doi.org/10.3390/w11102194 - 22 Oct 2019
Cited by 2 | Viewed by 875
Abstract
The venturi tube is a special kind of pipe which has been widely applied in many fields. Cavitation is one of the most important research issues for the Venturi tube. Hence, three key structural parameters (contraction angle, diffusion angle and contraction ratio) were [...] Read more.
The venturi tube is a special kind of pipe which has been widely applied in many fields. Cavitation is one of the most important research issues for the Venturi tube. Hence, three key structural parameters (contraction angle, diffusion angle and contraction ratio) were selected to investigate the influence of different factors on cavitation characteristics, using the computational fluid dynamics (CFD) method. A series of experiments for measuring the relationship between differential pressure and flow rate were carried out to verify the accuracy of the simulation method. Results showed that the simulation results had a high accuracy and the numerical method was feasible. The average vapor volume fraction of cross-section from the throat in the axial direction increased with increasing contraction angle. The cavity length increased with increasing contraction angle. The average volume fraction in the diffusion section rapidly decreased with increasing diffusion angle. The diffusion angle had no significant effect on the cavitation characteristics in the throat section and had a significant influence in the diffusion section. The average vapor volume fraction increased with decreasing contraction ratio. The contraction ratio had no significant effect on the cavity length under the same differential pressure. The average vapor volume fraction increased with decreasing contraction ratio. However, the variation in the throat section was less than the diffusion section. Under the same inlet and outlet pressure, the cavity lengths for different contraction ratios were basically the same, which indicated that the contraction ratio had no significant effect on the cavity length. Full article
(This article belongs to the Special Issue Pipeline Fluid Mechanics)
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Open AccessArticle
Geomorphodynamics in Argan Woodlands, South Morocco
Water 2019, 11(10), 2193; https://doi.org/10.3390/w11102193 - 22 Oct 2019
Cited by 2 | Viewed by 858
Abstract
The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to their use as a biomass resource in dry years and illegal firewood extraction. The intensification and expansion of agricultural land lead to a retreat of the [...] Read more.
The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to their use as a biomass resource in dry years and illegal firewood extraction. The intensification and expansion of agricultural land lead to a retreat of the wooded area, while the remaining argan open woodlands are often overgrazed. Thus, canopy-covered areas decrease while areas without vegetation cover between the argan trees increase. In total, 36 rainfall simulation experiments as well as 60 infiltration measurements were conducted to investigate the potential difference between tree-covered areas and bare intertree areas. In addition, 60 soil samples were taken under the trees and in the intertree areas parallel to the contour lines. Significant differences using a t-test were found between tree and intertree areas for the studied parameters Ksat, Kh, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content, and Mg-content. Surface runoff and soil losses were not as conclusive but showed similar trends. The results showed that argan trees influence the soil underneath significantly, while the soil in intertree areas is less protected and more degraded. It is therefore reasonable to assume further degradation of the soil when intertree areas extend further due to lack of rejuvenation of argan trees. Full article
(This article belongs to the Special Issue The Effect of Hydrology on Soil Erosion) Printed Edition available
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Open AccessFeature PaperArticle
Feasibility of the Use of Variable Speed Drives in Center Pivot Systems Installed in Plots with Variable Topography
Water 2019, 11(10), 2192; https://doi.org/10.3390/w11102192 - 21 Oct 2019
Cited by 3 | Viewed by 830
Abstract
Pumping systems are the largest energy consumers in center pivot irrigation systems. One action to reduce energy consumption is to adjust the pumping pressure to that which is strictly needed by using variable speed drives (VSDs). The objective of this study was to [...] Read more.
Pumping systems are the largest energy consumers in center pivot irrigation systems. One action to reduce energy consumption is to adjust the pumping pressure to that which is strictly needed by using variable speed drives (VSDs). The objective of this study was to determine the feasibility of including VSDs in pumping systems that feed center pivot systems operating in an area with variable topography. The VSPM (Variable Speed Pivot Model) was developed to perform hydraulic and energy analyses of center pivot systems using the EPANET hydraulics engine. This tool is able to determine the elevation of each tower for each position of the center pivot using any type of digital elevation model. It is also capable of simulating, in an accurate manner, the performance of the center pivot controlled with a VSD. The tool was applied to a real case study, located in Albacete, Spain. The results show a reduction in energy consumption of 12.2%, with specific energy consumptions of 0.214 and 0.244 kWh m−3 of distributed water obtained for the variable speed and fixed speed of the pumping station, respectively. The results also show that for an irrigation season, to meet the water requirements of the maize crop in the region of the study (627 mm), an average annual savings of 14,107.35 kWh was obtained, which resulted in an economic savings of 2821.47€. Full article
(This article belongs to the Special Issue Modelling and Management of Irrigation System) Printed Edition available
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Open AccessArticle
Modelling Climate Change’s Impact on the Hydrology of Natura 2000 Wetland Habitats in the Vistula and Odra River Basins in Poland
Water 2019, 11(10), 2191; https://doi.org/10.3390/w11102191 - 21 Oct 2019
Cited by 3 | Viewed by 859
Abstract
Climate change is expected to affect the water cycle through changes in precipitation, river streamflow, and soil moisture dynamics, and therefore, present a threat to groundwater and surface water-fed wetland habitats and their biodiversity. This article examines the past trends and future impacts [...] Read more.
Climate change is expected to affect the water cycle through changes in precipitation, river streamflow, and soil moisture dynamics, and therefore, present a threat to groundwater and surface water-fed wetland habitats and their biodiversity. This article examines the past trends and future impacts of climate change on riparian, water-dependent habitats within the special areas of conservation (SAC) of the Natura 2000 network located within Odra and Vistula River basins in Poland. Hydrological modelling using the Soil and Water Assessment Tool (SWAT) was driven by a set of nine EURO-CORDEX regional climate models under two greenhouse gas concentration trajectories. Changes in the duration of flooding and inundation events were used to assess climate change’s impact on surface water-fed wetland habitats. The groundwater-fed wetlands were evaluated on the basis of changes in soil water content. Information about the current conservation status, threats, and pressures that affect the habitats suggest that the wetlands might dry out. Increased precipitation projected for the future causing increased water supply to both surface water and groundwater-fed wetlands would lead to beneficial outcomes for habitats with good, average, or reduced conservation status. However, habitats with an excellent conservation status that are already in optimum condition could be negatively affected by climate change as increased soil water or duration of overbank flow would exceed their tolerance. Full article
(This article belongs to the Special Issue Riparian Vegetation in River Functioning)
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Open AccessArticle
A Study on the Response of the Hydrodynamic Environment to the Morphology of Radial Sand Ridges in the Coastal Waters of Jiangsu
Water 2019, 11(10), 2190; https://doi.org/10.3390/w11102190 - 21 Oct 2019
Viewed by 603
Abstract
A two-dimensional hydrodynamic model for the waters off the coast of Jiangsu, where there are radial sand ridges (RSRs) (hereinafter, the RSR area), was established based on measured topographic, tide level and tidal current data. Considering the complex topographic and geomorphic characteristics of [...] Read more.
A two-dimensional hydrodynamic model for the waters off the coast of Jiangsu, where there are radial sand ridges (RSRs) (hereinafter, the RSR area), was established based on measured topographic, tide level and tidal current data. Considering the complex topographic and geomorphic characteristics of the RSR group in this area, an unstructured grid was used for the calculation. A four-layer refinement was applied to the grid from outside to inside to better fit the complex topography. The simulations were performed to examine the response of the hydrodynamic environment to the morphology of the RSRs in three scenarios, namely, when there are natural RSRs, no RSRs, and partially reclaimed RSRs. When there are no or partially reclaimed RSRs, the tidal current field still exists in a radial pattern in the RSR area. The radial tidal current field is relatively stable and is not controlled by the morphologies of the RSRs. The topographic changes do not alter the distribution pattern of the radial tidal current field but do affect the local current fields. When there are no RSRs, the flood currents can directly reach Jianggang. Under practical conditions, the RSRs block the tidal currents during a flood tide to some extent. This phenomenon is particularly pronounced when the RSRs are partially reclaimed. For example, during an ebb tide, when the tidal currents encounter sand ridges or reclamation areas, their streamlines bend, and they flow around the obstacles. This change will affect the material transport, sediment deposition and seabed erosion. Full article
(This article belongs to the Special Issue Wetland Ecohydrology and Water Resource Management)
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Open AccessArticle
Impact of Orifice-to-Pipe Diameter Ratio on Leakage Flow: An Experimental Study
Water 2019, 11(10), 2189; https://doi.org/10.3390/w11102189 - 21 Oct 2019
Cited by 1 | Viewed by 617
Abstract
The traditional orifice discharge formula used to estimate the flow rate through a leak opening at a pipe wall often produces inaccurate results. This paper reports an original experimental study in which the influence of orifice-to-pipe diameter ratio on leakage flow rate was [...] Read more.
The traditional orifice discharge formula used to estimate the flow rate through a leak opening at a pipe wall often produces inaccurate results. This paper reports an original experimental study in which the influence of orifice-to-pipe diameter ratio on leakage flow rate was investigated for several internal/external flow conditions and orifice holes with different shapes. The results revealed that orifice-to-pipe diameter ratio (or pipe wall curvature) indeed influenced the leakage flow, with the discharge coefficient ( C d ) presenting a wide variation (0.60–0.85). As the orifice-to-pipe diameter ratio decreased, the values of C d systematically decreased from about 12% to 3%. Overall, the values of C d also decreased with β (ratio of pressure head differential at the orifice to wall thickness), as observed in previous studies. On the other hand, orifice shape, main pipe flow velocity, and external medium (water or air) all had a secondary effect on C d . The results obtained in the present study not only demonstrated that orifice-to-pipe diameter ratio affects the outflow, but also that real scale pipes may exhibit a relevant deviation of C d from the classical range (0.61–0.67) reported in the literature. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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Open AccessArticle
The Effect of Landscape Interventions on Groundwater Flow and Surface Runoff in a Watershed in the Upper Reaches of the Blue Nile
Water 2019, 11(10), 2188; https://doi.org/10.3390/w11102188 - 21 Oct 2019
Cited by 1 | Viewed by 640
Abstract
Anthropogenic landscape conversion from forest to agricultural land affects baseflow. Baseflow is a source of potable water and can be used for the irrigation of high value crops. Finding ways to increase base and inter flow (i.e., groundwater flow) is, therefore, essential for [...] Read more.
Anthropogenic landscape conversion from forest to agricultural land affects baseflow. Baseflow is a source of potable water and can be used for the irrigation of high value crops. Finding ways to increase base and inter flow (i.e., groundwater flow) is, therefore, essential for the improvement of the livelihood of rural inhabitants. Therefore, the objective is to investigate the effect of landscape interventions on stream discharge and, in particular, on groundwater flow. The Tikur-Wuha experimental watershed in the upper reaches of the Blue Nile was selected because discharge data were available before and after implementation of a suite of land management practices that, among others, enhanced the percolation of water to below the rootzone. The parameter efficient distributed (PED) model was used to separate overland flow from total flow. The groundwater flow index (GWFI), defined as the quotient of the annual groundwater flow to the total stream discharge at the outlet of the watershed, was calculated. Our analysis with the PED model showed that at similar annual rainfall amounts, more baseflow and less surface runoff was generated after the landscape intervention, which promoted deep infiltration of the rainwater. The decrease in surface runoff shortly after the implementation of the land management practices is similar to observations in other watersheds in the Ethiopian highlands. Full article
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Open AccessArticle
Predictive Water Virology: Hierarchical Bayesian Modeling for Estimating Virus Inactivation Curve
Water 2019, 11(10), 2187; https://doi.org/10.3390/w11102187 - 21 Oct 2019
Cited by 2 | Viewed by 1079
Abstract
Hazard analysis and critical control point (HACCP) are a series of actions to be taken to ensure product consumption safety. In food poisoning risk management, researchers in the field of predictive microbiology calculate the values that provide minimum stress (e.g., temperature and contact [...] Read more.
Hazard analysis and critical control point (HACCP) are a series of actions to be taken to ensure product consumption safety. In food poisoning risk management, researchers in the field of predictive microbiology calculate the values that provide minimum stress (e.g., temperature and contact time in heating) for sufficient microbe inactivation based on mathematical models. HACCP has also been employed for health risk management in sanitation safety planning (SSP), but the application of predictive microbiology to water-related pathogens is difficult because the variety of pathogen types and the complex composition of the wastewater matrix does not allow us to make a simple mathematical model to predict inactivation efficiency. In this study, we performed a systematic review and meta-analysis to construct predictive inactivation curves using free chlorine for enteric viruses based on a hierarchical Bayesian model using parameters such as water quality. Our model considered uncertainty among virus disinfection tests and difference in genotype-dependent sensitivity of a virus to disinfectant. The proposed model makes it possible to identify critical disinfection stress capable of reducing virus concentration that is below the tolerable concentration to ensure human health. Full article
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Open AccessArticle
Metals Leaching in Permeable Asphalt Pavement with Municipal Solid Waste Ash Aggregate
Water 2019, 11(10), 2186; https://doi.org/10.3390/w11102186 - 21 Oct 2019
Cited by 2 | Viewed by 604
Abstract
The leaching behaviors of four heavy metals (Zn, Pb, Cu and Cr) from unbounded municipal solid waste incineration-bottom ash aggregate (MSWI-BAA) and permeable asphalt (PA) mixture containing MSWI-BAA were investigated in the laboratory. The horizontal vibration extraction procedure (HVEP) test and a simulated [...] Read more.
The leaching behaviors of four heavy metals (Zn, Pb, Cu and Cr) from unbounded municipal solid waste incineration-bottom ash aggregate (MSWI-BAA) and permeable asphalt (PA) mixture containing MSWI-BAA were investigated in the laboratory. The horizontal vibration extraction procedure (HVEP) test and a simulated leaching experiment were conducted on MSWI-BAA with three particle sizes, but only the simulated leaching experiment was carried out on a type of PA specimen (PAC-13) with and without these MSWI-BAAs. Leaching data were analyzed to investigate the leaching characteristics, identify the factors affecting leaching and assess the impact on the surrounding environment. Results indicated that the leaching process was comprehensively influenced by contact time, leaching metal species and MSWI-BAA particle size, regardless of MSWI-BAA alone or used in PAC-13 mixture. The leaching concentrations of Cr, Zn and Pb from MSWI-BAA in HVEP testing was strongly related to MSWI-BAA particle size. The use of MSWI-BAA in PAC-13 mixture did not change the basic tendency of heavy metal leaching, but it led to an increase of Cr and Zn in leachate overall. The leachate from the MSWI-BAA and PAC-13 mixture with MSWI-BAA was shown to be safe for irrigation and would have very little negative impact on surrounding surface and underground water quality. Full article
(This article belongs to the Special Issue Urbanization under a Changing Climate – Impacts on Urban Hydrology )
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Open AccessCorrection
Correction: Castellini, M., et al. Spatial Variability of Soil Physical and Hydraulic Properties in a Durum Wheat Field: An Assessment by the BEST-Procedure. Water 2019, 11, 1434
Water 2019, 11(10), 2185; https://doi.org/10.3390/w11102185 - 21 Oct 2019
Viewed by 575
Abstract
The authors wish to make the following corrections to this paper [...] Full article
Open AccessArticle
Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal
Water 2019, 11(10), 2184; https://doi.org/10.3390/w11102184 - 20 Oct 2019
Cited by 2 | Viewed by 886
Abstract
The increasing concentration of nitrogen compounds in the groundwater is of a growing concern in terms of human health and groundwater quality. Although an excess of nitrogen compounds in the groundwater of the Kathmandu Valley has been reported, the seasonal variations of the [...] Read more.
The increasing concentration of nitrogen compounds in the groundwater is of a growing concern in terms of human health and groundwater quality. Although an excess of nitrogen compounds in the groundwater of the Kathmandu Valley has been reported, the seasonal variations of the fate of the nitrogen compounds and their relationships to the subsurface sediments are unknown. In this study, spatially distributed shallow dug well samples were collected during both the dry and wet seasons of 2016, and the nitrogen compound, chloride (Cl), and iron (Fe2+) concentrations were analyzed. Two shallow dug wells and one deep tube well were monitored monthly for 2 years. Although NH4-N concentrations were similar in the clay-dominated areas during both seasons (1 and 0.9 mg-N/L), they were lower in the gravel-dominated areas during wet season (1.8 > 0.6 mg-N/L). The NO3-N concentration differed depending upon the soil type which increased during the wet season (clay 4.9 < 13.6 mg-N/L and gravel 2.5 < 6.8 mg-N/L). The Fe2+ concentration, however, was low during the wet season (clay 2.7 > 0.4 mg/L and gravel 2.8 > 0.3 mg/L). Long-term analysis showed higher fluctuation of nitrogen compounds in the gravel-bearing areas than in the clay-bearing areas. Full article
(This article belongs to the Section Aquatic Systems—Quality and Contamination)
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Open AccessArticle
Quantify Piston and Preferential Water Flow in Deep Soil Using Cl and Soil Water Profiles in Deforested Apple Orchards on the Loess Plateau, China
Water 2019, 11(10), 2183; https://doi.org/10.3390/w11102183 - 19 Oct 2019
Cited by 1 | Viewed by 724
Abstract
Piston and preferential water flow are viewed as the two dominant water transport mechanisms regulating terrestrial water and solute cycles. However, it is difficult to accurately separate the two water flow patterns because preferential flow is not easy to capture directly in field [...] Read more.
Piston and preferential water flow are viewed as the two dominant water transport mechanisms regulating terrestrial water and solute cycles. However, it is difficult to accurately separate the two water flow patterns because preferential flow is not easy to capture directly in field environments. In this study, we take advantage of the afforestation induced desiccated deep soil, and directly quantify piston and preferential water flow using chloride ions (Cl) and soil water profiles, in four deforested apple orchards on the Loess Plateau. The deforestation time ranged from 3 to 15 years. In each of the four selected orchards, there was a standing orchard that was planted at the same time as the deforested one, and therefore the standing orchard was used to benchmark the initial Cl and soil water profiles of the deforested orchard. In the deforested orchards, piston flow was detected using the migration of the Cl front, and preferential flow was measured via soil water increase below the Cl front. Results showed that in the desiccated zone, Cl migrated to deeper soil after deforestation, indicating that the desiccated soil layer formed by the water absorption of deep-rooted apple trees did not completely inhibit the movement of water. Moreover, there was an evident increase in soil water below the downward Cl front, directly demonstrating the existence of preferential flow in deep soil under field conditions. Although pore water velocity was small in the deep loess, preferential water flow still accounted for 34–65% of total infiltrated water. This study presented the mechanisms that regulate movement of soil water following deforestation through field observations and advanced our understanding of the soil hydrologic process in deep soil. Full article
(This article belongs to the Section Hydrology and Hydrogeology)
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Open AccessArticle
Dewatering Characteristics and Inflow Prediction of Deep Foundation Pits with Partial Penetrating Curtains in Sand and Gravel Strata
Water 2019, 11(10), 2182; https://doi.org/10.3390/w11102182 - 19 Oct 2019
Cited by 2 | Viewed by 751
Abstract
The dewatering of deep foundation pits excavated in highly permeable geology usually requires waterproofing technologies to relieve groundwater flow. However, no effective prediction formula is yet available for determining water inflow in the presence of partial penetrating curtains. In this study, a dewatering [...] Read more.
The dewatering of deep foundation pits excavated in highly permeable geology usually requires waterproofing technologies to relieve groundwater flow. However, no effective prediction formula is yet available for determining water inflow in the presence of partial penetrating curtains. In this study, a dewatering project with partial penetrating curtains is analyzed via a finite difference method to show evident three-dimensional (3D) seepage characteristics. The standard curve and distortion functions are established under the assumption of an equivalent well by quantifying the blocking effects; thus, the empirical inflow prediction formulas for steady flow are further developed. Moreover, a dewatering design method based on the prediction formulas is proposed and applied to the field dewatering project in sand and gravel strata. Measured results show that dewatering efficiency is considerably enhanced by 3D flow, forming appropriate pressure distributions for dewatering construction. The uplift pressure below the pit bottom is controlled within a 25% safety margin to verify the reliability of the design method. Full article
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Open AccessArticle
Development of Nomogram for Debris Flow Forecasting Based on Critical Accumulated Rainfall in South Korea
Water 2019, 11(10), 2181; https://doi.org/10.3390/w11102181 - 19 Oct 2019
Viewed by 790
Abstract
Climate change causes extreme weather events worldwide such as increasing temperatures and changing rainfall patterns. With South Korea facing growing damage from the increased frequency of localized heavy rains. In particular, its steep slope lands, including mountainous areas, are vulnerable to damage from [...] Read more.
Climate change causes extreme weather events worldwide such as increasing temperatures and changing rainfall patterns. With South Korea facing growing damage from the increased frequency of localized heavy rains. In particular, its steep slope lands, including mountainous areas, are vulnerable to damage from landslides and debris flows. In addition, localized short-term heavy rains that occur in urban areas with extremely high intensity tend to lead a sharp increase in damage from soil-related disasters and cause huge losses of life and property. Currently, South Korea forecasts landslides and debris flows using the standards for forecasting landslides and heavy rains. However, as the forecasting is conducted separately for rainfall intensity and accumulated rainfall, this lacks a technique that reflects both amount and intensity of rainfall in an episode of localized heavy rainfall. In this study, aims to develop such a technique by collecting past cases of debris flow occurrences and rainfall events that accompanied debris flows to calculate the rainfall triggering index (RTI) reflecting accumulated rainfall and rainfall intensity. In addition, the RTI is converted into the critical accumulated rainfall ( R c ) to use rainfall information and provide real-time forecasting. The study classifies the standards for flow debris forecasting into three levels: ALERT (10–50%), WARNING (50–70%), and EMERGENCY (70% or higher), to provide a nomogram for 6 h, 12 h, and 24 h. As a result of applying this classification into the actual cases of Seoul, Chuncheon, and Cheongju, it is found that about 2–4 h of response time is secured from the point of the Emergency level to the occurrence of debris flows. Full article
(This article belongs to the Special Issue Debris Flows Research: Hazard and Risk Assessments)
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Open AccessArticle
Critical Factors for the Success of Rural Water Supply Services in Brazil
Water 2019, 11(10), 2180; https://doi.org/10.3390/w11102180 - 19 Oct 2019
Viewed by 897
Abstract
The universalization of drinking water in rural communities poses a great challenge to developing countries, where rural areas often receive poor water service coverage and limited attention from authorities. This scenario is the current reality in Brazil. The community management model of rural [...] Read more.
The universalization of drinking water in rural communities poses a great challenge to developing countries, where rural areas often receive poor water service coverage and limited attention from authorities. This scenario is the current reality in Brazil. The community management model of rural water services has proven to be a noteworthy approach to ensure the continuity of water supply where private and public entities do not operate. However, its sustainability depends on several aspects. The authors of the current paper performed a thorough review of relevant publications in the rural sanitation field of study using the Preferred Reporting Items for Systematic Reviews (PRISMA) methodology, which enabled the creation of a list of essential factors capable to ensure the sustainability of Rural Water Supply Services (RWSS). Using the Nominal Group Technique with a selection of participants from a national conference held in Brazil in 2015, specialists hierarchized the factors, demonstrating their perception of the most important aspects necessary in RWSS throughout Brazil. Consequently, the authors noticed the necessity of a strong enabling environment, which recognizes small communities and their local services. Water quality control, post-construction support and the existence of a financial scheme were also pointed out as important aspects to ensure RWSS’s sustainability. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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Open AccessArticle
Hypolimnetic Hypoxia Increases the Biomass Variability and Compositional Variability of Crustacean Zooplankton Communities
Water 2019, 11(10), 2179; https://doi.org/10.3390/w11102179 - 19 Oct 2019
Cited by 1 | Viewed by 782
Abstract
In freshwater lakes and reservoirs, climate change and eutrophication are increasing the occurrence of low-dissolved oxygen concentrations (hypoxia), which has the potential to alter the variability of zooplankton seasonal dynamics. We sampled zooplankton and physical, chemical and biological variables (e.g., temperature, dissolved oxygen, [...] Read more.
In freshwater lakes and reservoirs, climate change and eutrophication are increasing the occurrence of low-dissolved oxygen concentrations (hypoxia), which has the potential to alter the variability of zooplankton seasonal dynamics. We sampled zooplankton and physical, chemical and biological variables (e.g., temperature, dissolved oxygen, and chlorophyll a) in four reservoirs during the summer stratified period for three consecutive years. The hypolimnion (bottom waters) of two reservoirs remained oxic throughout the entire stratified period, whereas the hypolimnion of the other two reservoirs became hypoxic during the stratified period. Biomass variability (measured as the coefficient of the variation of zooplankton biomass) and compositional variability (measured as the community composition of zooplankton) of crustacean zooplankton communities were similar throughout the summer in the oxic reservoirs; however, biomass variability and compositional variability significantly increased after the onset of hypoxia in the two seasonally-hypoxic reservoirs. The increase in biomass variability in the seasonally-hypoxic reservoirs was driven largely by an increase in the variability of copepod biomass, while the increase in compositional variability was driven by increased variability in the dominance (proportion of total crustacean zooplankton biomass) of copepod taxa. Our results suggest that hypoxia may increase the seasonal variability of crustacean zooplankton communities. Full article
(This article belongs to the Section Aquatic Systems—Quality and Contamination)
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Open AccessArticle
Water Users Associations in Tanzania: Local Governance for Whom?
Water 2019, 11(10), 2178; https://doi.org/10.3390/w11102178 - 19 Oct 2019
Cited by 4 | Viewed by 1077
Abstract
In order to implement Integrated Water Resources Management (IWRM) according to good practice, governments and development agencies have promoted the setting-up of Water Users Associations (WUAs) as a broadly applicable model for water management at the local level. WUAs are promoted as key [...] Read more.
In order to implement Integrated Water Resources Management (IWRM) according to good practice, governments and development agencies have promoted the setting-up of Water Users Associations (WUAs) as a broadly applicable model for water management at the local level. WUAs are promoted as key to the rolling out of IWRM principles through a participative process. Using intensive qualitative data, this paper discusses Tanzanian WUAs in light of the Regulatory Framework within which they operate. I argue that although the government’s objectives are to achieve an equitable and sustainable allocation of water resources, the formalisation of water allocation has led to the exclusion of specific water users. This paper focuses on the Great Ruaha River Catchment (GRRC), where water scarcity has led to competition between investors and small-scale water users. The GRRC is an environment in which formal and informal practices overlap, due to legal pluralism and the incremental implementation of water governance frameworks. This study calls for a reassessment of the role of WUAs in Tanzania. There is a clear gap between the theoretical clarity of tasks handed to WUAs (particularly their role in formalising access to water), and the messiness of everyday practice. Full article
(This article belongs to the Special Issue Selected Papers from 2019 World Water Week)
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Open AccessArticle
Using Water Stable Isotopes for Identifying Groundwater Recharge Sources of the Unconfined Alluvial Zagreb Aquifer (Croatia)
Water 2019, 11(10), 2177; https://doi.org/10.3390/w11102177 - 19 Oct 2019
Cited by 5 | Viewed by 879
Abstract
The main purpose of this study was to understand the interactions between precipitation, surface water, and groundwater in the Zagreb aquifer system using water stable isotopes. The Zagreb aquifer is of the unconfined type and strongly hydraulically connected to the Sava River. As [...] Read more.
The main purpose of this study was to understand the interactions between precipitation, surface water, and groundwater in the Zagreb aquifer system using water stable isotopes. The Zagreb aquifer is of the unconfined type and strongly hydraulically connected to the Sava River. As the groundwater is the main source of drinking water for one million inhabitants, it is essential to investigate each detail of the recharge processes of the aquifer to ensure adequate protection of the groundwater. Measuring the content of water stable isotopes in surface waters and groundwater enabled the creation of two- and three-component mixing models based on the isotopic mass balance for the purpose of the quantification of each recharge component. The mixing models gave ambiguous results. Observation wells equally distant from the Sava River did not have the same recharge component ratio. This indicated that there were more factors (in addition to the distance from the river) that were affecting groundwater recharge, and the properties of the unsaturated zone and surface cover data were therefore also taken into consideration. The thickness of the unsaturated zone and the characteristics of different soil types were identified as important factors in the recharge of the Zagreb aquifer. The areas with high thickness of the unsaturated zone and well-permeable soil had a very similar recharge component ratio to the areas with small thickness of the unsaturated zone but low-permeable soil. Full article
(This article belongs to the Special Issue Groundwater-Surface Water Interactions) Printed Edition available
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Open AccessCommunication
Freshwater Supply to Metropolitan Shanghai: Issues of Quality from Source to Consumers
Water 2019, 11(10), 2176; https://doi.org/10.3390/w11102176 - 19 Oct 2019
Viewed by 851
Abstract
Shanghai is experiencing drinking water supply problems that are caused by heavy pollution of its raw water supply, deficiencies in its treatment processes, and water quality deterioration in the distribution system. However, little attention has been paid these problems of water quality in [...] Read more.
Shanghai is experiencing drinking water supply problems that are caused by heavy pollution of its raw water supply, deficiencies in its treatment processes, and water quality deterioration in the distribution system. However, little attention has been paid these problems of water quality in raw water, water treatment, and household drinking water. Based on water quality data from 1979 to 2016, we show that microbes (TBC), eutrophication (TP, TN, and NH3–N), heavy metals (Fe, Mn, and Hg), and organic contamination (chemical oxygen demand (COD), detergent (Linear Alklybenzene Sulfonate, LAS), and volatile phenols (VP)) pollute the raw water sources of the Huangpu River and the Changjiang (Yangtze River) estuary. The average concentrations of these contaminants in the Huangpu River are almost double that of the Changjiang estuary, forcing a rapid shift to the Changjiang estuary for raw water. In spite of filtering and treatment, TN, NH3–N, Fe, COD, and chlorine maxima of the treated water and drinking water still exceed the Chinese National Standard. We determine that the relevant threats from the water source to household water in Shanghai are: (1) eutrophication arising from highly concentrated TN, TP, COD, and algal density in the raw water; (2) increasing salinity in the river estuary, especially at the Qingcaosha Reservoir (currently the major freshwater source for Shanghai); (3) more than 50% of organic constituents and by-products remain in treated water; and, (4) bacteria and turbidity increase in the course of water delivery to users. The analysis presents a holistic assessment of the water quality threats to metropolitan Shanghai in relation to the city’s rapid development. Full article
(This article belongs to the Section Urban Water Management)
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Open AccessArticle
Sorption Properties of the Bottom Sediment of a Lake Restored by Phosphorus Inactivation Method 15 Years after the Termination of Lake Restoration Procedures
Water 2019, 11(10), 2175; https://doi.org/10.3390/w11102175 - 19 Oct 2019
Cited by 3 | Viewed by 738
Abstract
Artificial mixing and phosphorus inactivation methods using aluminum compounds are among the most popular lake restoration methods. Długie Lake (Olsztyńskie Lakeland, Poland) was restored using these two methods. Primarily, P precipitation and inactivation methods significantly increased the sorption properties of Długie Lake bottom [...] Read more.
Artificial mixing and phosphorus inactivation methods using aluminum compounds are among the most popular lake restoration methods. Długie Lake (Olsztyńskie Lakeland, Poland) was restored using these two methods. Primarily, P precipitation and inactivation methods significantly increased the sorption properties of Długie Lake bottom sediment. Fifteen years after the termination of the restoration procedure, the alum-modified “active” sediment layer still has higher P adsorption abilities, which can limit P internal loading. Relatively low amounts of phosphates in the near-bottom water of Długie Lake, even in anoxia, as well as the fact that the assessed maximum sediment P sorption capacity is still higher than NH4Cl–P (labile P) and BD–P (Fe-bound P) sum (“native exchangeable P”), confirm that hypothesis. Among the tested P adsorption models for the sediment, the double Langmuir model showed the best fit to the experimental data (the highest R2 values). This may indicate that phosphorus adsorption by the tested sediments most likely occurs through phosphate binding at two types of active sorption sites. P adsorption by the studied lake sediment during experiments was significantly connected to aluminum content in sediment. The research into the adsorption properties of sediment can be used as a tool for the evaluation of lake restoration effects. Full article
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Open AccessArticle
Variations of Drought Tendency, Frequency, and Characteristics and Their Responses to Climate Change under CMIP5 RCP Scenarios in Huai River Basin, China
Water 2019, 11(10), 2174; https://doi.org/10.3390/w11102174 - 19 Oct 2019
Cited by 3 | Viewed by 703
Abstract
Huai River Basin (HRB) is an important food and industrial production area and a frequently drought-affected basin in eastern China. It is necessary to consider the future drought development for reducing the impact of drought disasters. Three global circulation models (GCMs) from Coupled [...] Read more.
Huai River Basin (HRB) is an important food and industrial production area and a frequently drought-affected basin in eastern China. It is necessary to consider the future drought development for reducing the impact of drought disasters. Three global circulation models (GCMs) from Coupled Model Intercomparison Project phase 5 (CMIP5), such as CNRM-CM5 (CNR), HadGEM2-ES (Had) and MIROC5 (MIR), were used to assessment the future drought conditions under two Representative Concentration Pathways (RCPs) scenarios, namely, RCP4.5 and RCP8.5. The standardized precipitation evapotranspiration index (SPEI), statistical method, Mann-Kendall test, and run theory were carried out to study the variations of drought tendency, frequency, and characteristics and their responses to climate change. The research showed that the three CMIP5 models differ in describing the future seasonal and annual variations of precipitation and temperature in the basin and thus lead to the differences in describing drought trends, frequency, and drought characteristics, such as drought severity, drought duration, and drought intensity. However, the drought trend, frequency, and characteristics in the future are more serious than the history. The drought frequency and characteristics tend to be strengthened under the scenario of high concentration of RCP8.5, and the drought trend is larger than that of low concentration of RCP4.5. The lower precipitation and the higher temperature are the main factors affecting the occurrence of drought. All three CMIP5 models show that precipitation would increase in the future, but it could not offset the evapotranspiration loss caused by significant temperature rise. The serious risk of drought in the future is still higher. Considering the uncertainty of climate models for simulation and prediction, attention should be paid to distinguish the effects of different models in the future drought assessment. Full article
(This article belongs to the Section Water Use and Scarcity)
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Open AccessArticle
Filtration of Uncharged Solutes: An Assessment of Steric Effect by Transport and Adsorption Modelling
Water 2019, 11(10), 2173; https://doi.org/10.3390/w11102173 - 19 Oct 2019
Viewed by 601
Abstract
The major aim of this work was to understand and estimate the evolution of the membrane selectivity of neutral solutes after the filtration of protein or amino acid solutions. Classical methodologies led to the estimation of the mean pore radius, different for each [...] Read more.
The major aim of this work was to understand and estimate the evolution of the membrane selectivity of neutral solutes after the filtration of protein or amino acid solutions. Classical methodologies led to the estimation of the mean pore radius, different for each filtrated neutral solute. The use of pore size distribution from nitrogen adsorption/desorption experiments enabled a good description of hydraulic and selectivity performances. The modification of the membrane hydraulic properties after the successive filtration of protein solutions revealed that the decrease is quasi linear, the same for all the studied membranes and independent of prior tests. According to the experimental observations, an adsorption model was developed, considering a layer by layer adsorption in the larger pores of the membrane. The predictive obtained results are in good agreement with the experimental rejection rates, validating the assumptions. Full article
(This article belongs to the Special Issue Wastewater Treatment, Valorization and Reuse)
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Open AccessArticle
Improved Water Services Cooperation through Clarification of Rules and Roles
Water 2019, 11(10), 2172; https://doi.org/10.3390/w11102172 - 19 Oct 2019
Viewed by 724
Abstract
Water services face global challenges, many of which are institutional by nature. While technical solutions may suit several situations, institutional frameworks are likely to vary more. On the basis of constructive research approach and new institutional economics we analyze and illustrate water services [...] Read more.
Water services face global challenges, many of which are institutional by nature. While technical solutions may suit several situations, institutional frameworks are likely to vary more. On the basis of constructive research approach and new institutional economics we analyze and illustrate water services and the roles of various water sector actors in Finnish water utility setting using the “soccer analogy” by the Nobel Laureate D.C. North: Institutions are the “formal and informal rules of the game” while organizations are the “players”. Additionally, we assess the Finnish water governance system and discuss issues of scale and fragmentation and distinguish terms water provision and production. Finally, we elaborate the limitations of the soccer analogy to water services through ownership of the systems. According to the soccer analogy, inclusive institutional development requires skillful players (competent staff), team play (collaboration), proper coaching (education), supporters (citizens, media), managers (policymakers), and referees (authorities). We argue that institutional diversity and player/stakeholder collaboration are the foundation for enhancing good multi-level water governance, and that water management, although fragmented, should be seen as a connector of different sectors. For successful outcomes, scientific results should be communicated to public in more common language. Full article
(This article belongs to the Special Issue Selected Papers from 2019 World Water Week)
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Open AccessArticle
Application and Evaluation of the China Meteorological Assimilation Driving Datasets for the SWAT Model (CMADS) in Poorly Gauged Regions in Western China
Water 2019, 11(10), 2171; https://doi.org/10.3390/w11102171 - 18 Oct 2019
Cited by 1 | Viewed by 734
Abstract
The temporal and spatial differentiation of the underlying surface in East Asia is complex. Due to a lack of meteorological observation data, human cognition and understanding of the surface processes (runoff, snowmelt, soil moisture, water production, etc.) in the area have been greatly [...] Read more.
The temporal and spatial differentiation of the underlying surface in East Asia is complex. Due to a lack of meteorological observation data, human cognition and understanding of the surface processes (runoff, snowmelt, soil moisture, water production, etc.) in the area have been greatly limited. With the Heihe River Basin, a poorly gauged region in the cold region of Western China, selected as the study area, three meteorological datasets are evaluated for their suitability to drive the Soil and Water Assessment Tool (SWAT): China Meteorological Assimilation Driving Datasets for the SWAT model (CMADS), Climate Forecast System Reanalysis (CFSR), and Traditional Weather Station (TWS). Resultingly, (1) the runoff output of CMADS + SWAT mode is generally better than that of the other two modes (CFSR + SWAT and TWS + SWAT) and the monthly and daily Nash–Sutcliffe efficiency ranges of the CMADS + SWAT mode are 0.75–0.95 and 0.58–0.77, respectively; (2) the CMADS + SWAT and TWS + SWAT results were fairly similar to the actual data (especially for precipitation and evaporation), with the results produced by CMADS + SWAT lower than those produced by TWS + SWAT; (3) the CMADS + SWAT mode has a greater ability to reproduce water balance than the other two modes. Overestimation of CFSR precipitation results in greater error impact on the uncertainty output of the model, whereas the performances of CMADS and TWS are more similar. This study addresses the gap in the study of surface processes by CMADS users in Western China and provides an important scientific basis for analyzing poorly gauged regions in East Asia. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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Open AccessArticle
An Index of Aquiclude Destabilization for Mining-Induced Roof Water Inrush Forecasting: A Case Study
Water 2019, 11(10), 2170; https://doi.org/10.3390/w11102170 - 18 Oct 2019
Cited by 1 | Viewed by 1308
Abstract
Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case [...] Read more.
Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case study of roof water inrush accidents in Cuimu coal mine, China. The relation between roof water inrush and water level variation in the aquifer, and the characteristics of aquiclude deformation, were studied in this assessment. Using the developed assessment criteria, the likelihood of roof water inrush was categorized into different risk levels, which were followed by a proposal for roof water inrush control measures. The main findings of this study are: a) in Cuimu coal mine, the waterbody in the bed separation between the upper aquifer and the aquiclude directly causes the inrush, and inrush occurs after the water level declines in the aquifer; b) tension-induced horizontal strains of aquiclude can be regarded as the index to evaluate the stability of aquiclude affected by underground coal mining—roof water inrush occurs when the maximum horizontal strain reaches a threshold of 10mm/m—c) based on the critical mining height for aquiclude instability, and the different thicknesses of barrier layers, high-risk zones are identified and inrush controls are proposed. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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Open AccessArticle
Modelling Methane and Nitrous Oxide Emissions from Rice Paddy Wetlands in India Using Artificial Neural Networks (ANNs)
Water 2019, 11(10), 2169; https://doi.org/10.3390/w11102169 - 18 Oct 2019
Cited by 2 | Viewed by 717 | Correction
Abstract
Paddy fields, which are shallow man-made wetlands, are estimated to be responsible for ~11% of the total methane emissions attributed to anthropogenic sources. The role of water use in driving these emissions, and the apportioning of the emissions to individual countries engaged in [...] Read more.
Paddy fields, which are shallow man-made wetlands, are estimated to be responsible for ~11% of the total methane emissions attributed to anthropogenic sources. The role of water use in driving these emissions, and the apportioning of the emissions to individual countries engaged in paddy cultivation, are aspects that have been mired in controversy and disagreement. This is largely due to the fact that methane (CH4) emissions not only change with the cultivar type but also regions, climate, soil type, soil conditions, manner of irrigation, type and quantity of fertilizer added—to name a few. The factors which can influence these aspects also encompass a wide range, and have origins in causes which can be physical, chemical, biological, and combinations of these. Exceedingly complex feedback mechanisms, exerting different magnitudes and types of influences on CH4 emissions under different conditions, are operative. Similar is the case of nitrous oxide (N2O); indeed, the present level of understanding of the factors which influence the quantum of its emission is still more patchy. This makes it difficult to even understand precisely the role of the myriad factors, less so model them. The challenge is made even more daunting by the fact that accurate and precise data on most of these aspects is lacking. This makes it nearly impossible to develop analytical models linking causes with effects vis a vis CH4 and N2O emissions from paddy fields. For situations like this the bioinspired artificial intelligence technique of artificial neural network (ANN), which can model a phenomenon on the basis of past data and without the explicit understanding of the mechanism phenomena, may prove useful. However, no such model for CH4 or N2O has been developed so far. Hence the present work was undertaken. It describes ANN-based models developed by us to predict CH4 and N2O emissions using soil characteristics, fertilizer inputs, and rice cultivar yield as inputs. Upon testing the predictive ability of the models with sets of data not used in model development, it was seen that there was excellent agreement between model forecasts and experimental findings, leading to correlations coefficients of 0.991 and 0.96, and root mean square error (RMSE) of 11.17 and 261.3, respectively, for CH4 and N2O emissions. Thus, the models can be used to estimate CH4 and N2O emissions from all those continuously flooded paddy wetlands for which data on total organic carbon, soil electrical conductivity, applied nitrogen, phosphorous and potassium, NPK, and grain yield is available. Full article
(This article belongs to the Special Issue Water Quality and Ecosystems in Times of Climate Change)
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