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Water, Volume 7, Issue 8 (August 2015) – 31 articles , Pages 4026-4592

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10091 KiB  
Article
Impacts of the 2013 Extreme Flood in Northeast China on Regional Groundwater Depth and Quality
by Xihua Wang, Guangxin Zhang and Yi Jun Xu
Water 2015, 7(8), 4575-4592; https://doi.org/10.3390/w7084575 - 24 Aug 2015
Cited by 18 | Viewed by 5395
Abstract
Flooding’s impact on shallow groundwater is not well investigated. In this study, we analyzed changes in the depth and quality of a regional shallow aquifer in the 10.9 × 104 km2 Sanjiang Plain, Northeast China, following a large flood in the [...] Read more.
Flooding’s impact on shallow groundwater is not well investigated. In this study, we analyzed changes in the depth and quality of a regional shallow aquifer in the 10.9 × 104 km2 Sanjiang Plain, Northeast China, following a large flood in the summer of 2013. Pre- (2008–2012) and post-flood records on groundwater table depth and groundwater chemistry were gathered from 20 wells across the region. Spatial variability of groundwater recharge after the flood was assessed and the changes in groundwater quality in the post-flood period were determined. The study found a considerable increase in the groundwater table after the 2013 summer flood across the region, with the largest (3.20 m) and fastest (0.80 m·s−1) rising height occurring in western Sanjiang Plain. The rising height and velocity gradually declined from the west to the east of the plain. For the entire region, we estimated an average recharge height of 1.24 m for the four flood months (June to September) of 2013. Furthermore, we found that the extreme flood reduced nitrate (NO3−) and chloride (Cl−) concentrations and electrical conductivity (EC) in shallow groundwater in the areas that were close to rivers, but increased NO3− and Cl− concentrations and EC in the areas that were under intensive agricultural practices. As the region’s groundwater storage and quality have been declining due to the rapidly increasing rice cultivation, this study shows that floods should be managed as water resources to ease the local water shortage as well as shallow groundwater pollution. Full article
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290 KiB  
Review
Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview
by Xixi Wang
Water 2015, 7(8), 4552-4574; https://doi.org/10.3390/w7084552 - 21 Aug 2015
Cited by 37 | Viewed by 7410
Abstract
Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function [...] Read more.
Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function in evaporation is still a challenging topic with significant remaining issues. Thus, an overview of the previous findings will be very beneficial for identifying further research needs that aim to advance our understanding of the vapor flow resistance (VFR) effect on soil water evaporation as influenced by characteristics of the dry soil layer (DSL) and evaporation zone (EZ). In this regard, six measurement and four modeling studies were overviewed. The results of these overviewed studies, along with the others, affirm the conceptual dynamics of DSL and EZ during drying or wetting processes (but not both) within dry sandy soils. The VFR effect tends to linearly increase with DSL thickness (δ) when δ < 5 cm and is likely to increase as a logarithmic function of δ when δ ≥ 5 cm. The vaporization-condensation-movement (VCM) dynamics in a DSL depend on soil textures: sandy soils can form a thick (10 to 20 cm) DSL while sandy clay soils may or may not have a clear DSL; regardless, a DSL can function as a transient EZ, a vapor condensation zone, and/or a vapor transport medium. Based on the overview, further studies will need to generate long-term continuous field data, develop hydraulic functions for very dry soils, and establish an approach to quantify the dynamics and VFR effects of DSLs during wetting-drying cycles as well as take into account such effects when using conventional (e.g., Penman-Monteith) evaporation models. Full article
(This article belongs to the Special Issue Hydrologic System Analysis, Patterns, and Predictions for Arid and Semi-arid Environment)
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2763 KiB  
Article
Transferability of Monitoring Data from Neighboring Streams in a Physical Habitat Simulation
by Byungwoong Choi, Sung-Uk Choi and Hojeong Kang
Water 2015, 7(8), 4537-4551; https://doi.org/10.3390/w7084537 - 20 Aug 2015
Cited by 5 | Viewed by 5695
Abstract
Habitat simulation models heavily rely on monitoring data, which can have serious effects on the success of a physical habitat simulation. However, if data monitored in a study reach are not available or insufficient, then data from neighboring streams are commonly used. The [...] Read more.
Habitat simulation models heavily rely on monitoring data, which can have serious effects on the success of a physical habitat simulation. However, if data monitored in a study reach are not available or insufficient, then data from neighboring streams are commonly used. The problem is that the impact of using data from neighboring streams has rarely been studied before. Motivated by this, we report herein on an investigation of the transferability of data from neighboring streams in a physical habitat simulation. The study area is a 2.5 km long reach located downstream from a dam in the Dal River, Korea. Zacco platypus was selected as the target fish for the physical habitat simulation. Monitoring data for the Dal River and three neighboring streams were obtained. First, similarities in the data related to channel geometry and in the observed distribution of the target species were examined. Principal Component Analysis (PCA) was also carried out to see the characteristics of the habitat use of the target species. Habitat Suitability Curves (HSCs) were constructed using the Gene Expression Programming (GEP) model, and improved Generalized Habitat Suitability Curves (GHSCs) were proposed. The physical habitat simulations were then performed. The Composite Suitability Index (CSI) distributions were predicted, and the impact of using data from the neighboring streams was investigated. The results indicated that the use of data from a neighboring stream even in the same watershed can result in large errors in the prediction of CSI. The physical habitat simulation with the improved GHSCs was found to best predict the CSI. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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327 KiB  
Article
Forms of Nutrients in Rivers Flowing into Lake Chaohu: A Comparison between Urban and Rural Rivers
by Lei Zhang, Shiguang Shao, Cheng Liu, Tingting Xu and Chengxin Fan
Water 2015, 7(8), 4523-4536; https://doi.org/10.3390/w7084523 - 19 Aug 2015
Cited by 33 | Viewed by 6819
Abstract
Nutrient inputs from rivers play an important role in lake eutrophication. To compare the forms characteristics of phosphorus (P) and nitrogen (N) in rivers flowing through rural and urban areas, water samples were collected seasonally from five urban rivers and six rural rivers [...] Read more.
Nutrient inputs from rivers play an important role in lake eutrophication. To compare the forms characteristics of phosphorus (P) and nitrogen (N) in rivers flowing through rural and urban areas, water samples were collected seasonally from five urban rivers and six rural rivers flowing to Lake Chaohu, China. Higher total phosphorus (TP), particulate phosphorus (PP), soluble reactive phosphorus (SRP), and dissolved nonreactive phosphorus (DNP) concentrations and SRP/TP percentages were observed in urban rivers than in rural rivers, and PP/TP and DNP/TP ratios were lower in urban rivers than in rural rivers. The concentrations of total nitrogen (TN) and all N forms other than dissolved organic nitrogen (DON) were significantly higher in urban rivers than in rural rivers. NH4+/TN levels were higher in urban rivers, whereas PN/TN and DON/TN ratios were significantly lower in urban rivers compared with rural rivers. NO3−/TN and NO2−/TN levels were similar between the two groups of rivers. TP, BD-P, and NaOH-P levels in urban river surface sediments were significantly higher than those in rural rivers. NaOH-P/TP ratios were significantly elevated in urban rivers, whereas HCl-P/TP and Res-P/TP ratios were significantly lower compared with rural rivers. Urban rivers have transferred large quantities of NH4+ and SRP into Lake Chaohu, resulting in higher TP and TN levels and NH4+/TN and SRP/TP ratios. Decreasing the input of NH4+ and SRP into urban rivers is a high priority for mitigating eutrophication and algal blooms in Lake Chaohu. Full article
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1962 KiB  
Communication
Agricultural Rivers at Risk: Dredging Results in a Loss of Macroinvertebrates. Preliminary Observations from the Narew Catchment, Poland
by Mateusz Grygoruk, Magdalena Frąk and Aron Chmielewski
Water 2015, 7(8), 4511-4522; https://doi.org/10.3390/w7084511 - 17 Aug 2015
Cited by 17 | Viewed by 6037
Abstract
Ecosystem deterioration in small lowland agricultural rivers that results from river dredging entails a significant threat to the appropriate ecohydrological conditions of these water bodies, expressed as homogenization of habitats and loss of biodiversity. Our study was aimed at a comparison of abundance [...] Read more.
Ecosystem deterioration in small lowland agricultural rivers that results from river dredging entails a significant threat to the appropriate ecohydrological conditions of these water bodies, expressed as homogenization of habitats and loss of biodiversity. Our study was aimed at a comparison of abundance and taxonomic structure of bottom-dwelling macroinvertebrates in dredged and non-dredged stretches of small lowland rivers and tributaries of the middle Narew River, namely: Czaplinianka, Turośnianka, Dąb, and Ślina. The experimental setup was (1) to collect samples of the bottom material from the river stretches that either persisted in a non-modified state (dredging was not done there in the last few years) or had been subjected to river dredging in the year of sampling; and (2) to analyze the abundance and taxonomic structure of macroinvertebrates in the collected samples. The study revealed that at the high level of statistical significance (from p = 0.025 to p = 0.001), the total abundance of riverbed macroinvertebrates in the dredged stretches of the rivers analyzed was approximately 70% lower than in non-dredged areas. We state that the dredging of small rivers in agricultural landscapes seriously affects their ecological status by negatively influencing the concentrations and species richness of benthic macroinvertebrates. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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1855 KiB  
Article
Field Evaluation of a Stormwater Treatment Train with Pit Baskets and Filter Media Cartridges in Southeast Queensland
by Darren Drapper and Andy Hornbuckle
Water 2015, 7(8), 4496-4510; https://doi.org/10.3390/w7084496 - 17 Aug 2015
Cited by 11 | Viewed by 8491
Abstract
Field monitoring of a stormwater treatment train has been underway between November 2013 and May 2015 at a townhouse development located at Ormiston, southeast Queensland. The research was undertaken to evaluate the effectiveness of a 200 micron mesh pit basket in a 900 [...] Read more.
Field monitoring of a stormwater treatment train has been underway between November 2013 and May 2015 at a townhouse development located at Ormiston, southeast Queensland. The research was undertaken to evaluate the effectiveness of a 200 micron mesh pit basket in a 900 square format and an 850 mm high media filtration cartridge system for removing total suspended solids and nutrients from stormwater runoff. The monitoring protocol was developed with Queensland University of Technology (QUT), reflecting the Auckland Regional Council Proprietary Device Evaluation Protocol (PDEP) and United States Urban Stormwater BMP Performance Monitoring Manual with some minor improvements reflecting local conditions. During the 18 month period, more than 30 rain events have occurred, of which nine comply with the protocol. The Efficiency Ratio (ER) observed for the treatment devices are 32% total suspended solids (TSS), 37% for total phosphorus (TP) and 38% total nitrogen (TN) for the pit basket, and an Efficiency Ratio of 87% TSS, 55% TP and 42% TN for the cartridge filter. The performance results on nine events have been observed to be significantly different statistically (p < 0.05) for the filters but not the pit baskets. The research has also identified the significant influence of analytical variability on performance results, specifically when influent concentrations are near the limits of detection. Full article
(This article belongs to the Special Issue Ecological Monitoring, Assessment, and Management in Freshwater Systems)
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1237 KiB  
Article
Heuristic Methods for Reservoir Monthly Inflow Forecasting: A Case Study of Xinfengjiang Reservoir in Pearl River, China
by Chun-Tian Cheng, Zhong-Kai Feng, Wen-Jing Niu and Sheng-Li Liao
Water 2015, 7(8), 4477-4495; https://doi.org/10.3390/w7084477 - 17 Aug 2015
Cited by 41 | Viewed by 7223
Abstract
Reservoir monthly inflow is rather important for the security of long-term reservoir operation and water resource management. The main goal of the present research is to develop forecasting models for the reservoir monthly inflow. In this paper, artificial neural networks (ANN) and support [...] Read more.
Reservoir monthly inflow is rather important for the security of long-term reservoir operation and water resource management. The main goal of the present research is to develop forecasting models for the reservoir monthly inflow. In this paper, artificial neural networks (ANN) and support vector machine (SVM) are two basic heuristic forecasting methods, and genetic algorithm (GA) is employed to choose the parameters of the SVM. When forecasting the monthly inflow data series, both approaches are inclined to acquire relatively poor performances. Thus, based on the thought of refined prediction by model combination, a hybrid forecasting method involving a two-stage process is proposed to improve the forecast accuracy. In the hybrid method, the ANN and SVM are, first, respectively implemented to forecast the reservoir monthly inflow data. Then, the processed predictive values of both ANN and SVM are selected as the input variables of a newly-built ANN model for refined forecasting. Three models, ANN, SVM, and the hybrid method, are developed for the monthly inflow forecasting in Xinfengjiang reservoir with 71-year discharges from 1944 to 2014. The comparison of results reveal that three models have satisfactory performances in the Xinfengjiang reservoir monthly inflow prediction, and the hybrid method performs better than ANN and SVM in terms of five statistical indicators. Thus, the hybrid method is an efficient tool for the long-term operation and dispatching of Xinfengjiang reservoir. Full article
(This article belongs to the Special Issue Use of Meta-Heuristic Techniques in Rainfall-Runoff Modelling)
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5070 KiB  
Article
Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model
by Chao Wang, Jiandong Yang and Håkan Nilsson
Water 2015, 7(8), 4446-4476; https://doi.org/10.3390/w7084446 - 13 Aug 2015
Cited by 19 | Viewed by 9985
Abstract
A model for simulating vertical water level fluctuations with coupled liquid and gas phases is presented. The Preissmann implicit scheme is used to linearize the governing equations for one-dimensional transient flow for both liquid and gas phases, and the linear system is solved [...] Read more.
A model for simulating vertical water level fluctuations with coupled liquid and gas phases is presented. The Preissmann implicit scheme is used to linearize the governing equations for one-dimensional transient flow for both liquid and gas phases, and the linear system is solved using the chasing method. Some classical cases for single liquid and gas phase transients in pipelines and networks are studied to verify that the proposed methods are accurate and reliable. The implicit scheme is extended using a dynamic mesh to simulate the water level fluctuations in a U-tube and an open surge tank without consideration of the gas phase. Methods of coupling liquid and gas phases are presented and used for studying the transient process and interaction between the phases, for gas phase limited in a chamber and gas phase transported in a pipeline. In particular, two other simplified models, one neglecting the effect of the gas phase on the liquid phase and the other one coupling the liquid and gas phases asynchronously, are proposed. The numerical results indicate that the asynchronous model performs better, and are finally applied to a hydropower station with surge tanks and air shafts to simulate the water level fluctuations and air speed. Full article
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2301 KiB  
Article
Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China
by Jiao Ding, Yuan Jiang, Lan Fu, Qi Liu, Qiuzhi Peng and Muyi Kang
Water 2015, 7(8), 4427-4445; https://doi.org/10.3390/w7084427 - 12 Aug 2015
Cited by 153 | Viewed by 13022
Abstract
Understanding the relationship between land use and surface water quality is necessary for effective water management. We estimated the impacts of catchment-wide land use on water quality during the dry and rainy seasons in the Dongjiang River basin, using remote sensing, geographic information [...] Read more.
Understanding the relationship between land use and surface water quality is necessary for effective water management. We estimated the impacts of catchment-wide land use on water quality during the dry and rainy seasons in the Dongjiang River basin, using remote sensing, geographic information systems and multivariate statistical techniques. The results showed that the 83 sites can be divided into three groups representing different land use types: forest, agriculture and urban. Water quality parameters exhibited significant variations between the urban-dominated and forest-dominated sites. The proportion of forested land was positively associated with dissolved oxygen concentration but negatively associated with water temperature, electrical conductivity, permanganate index, total phosphorus, total nitrogen, ammonia nitrogen, nitrate nitrogen and chlorophyll-a. The proportion of urban land was strongly positively associated with total nitrogen and ammonia nitrogen concentrations. Forested and urban land use had stronger impacts on water quality in the dry season than in the rainy season. However, agricultural land use did not have a significant impact on water quality. Our study indicates that urban land use was the key factor affecting water quality change, and limiting point-source waste discharge in urban areas during the dry season would be critical for improving water quality in the study area. Full article
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1422 KiB  
Article
Evaluation of an Empirical Reservoir Shape Function to Define Sediment Distributions in Small Reservoirs
by Bogusław Michalec
Water 2015, 7(8), 4409-4426; https://doi.org/10.3390/w7084409 - 12 Aug 2015
Cited by 9 | Viewed by 5592
Abstract
Understanding and defining the spatial distribution of sediment deposited in reservoirs is essential not only at the design stage but also during the operation. The majority of research concerns the distribution of sediment deposition in medium and large water reservoirs. Most empirical methods [...] Read more.
Understanding and defining the spatial distribution of sediment deposited in reservoirs is essential not only at the design stage but also during the operation. The majority of research concerns the distribution of sediment deposition in medium and large water reservoirs. Most empirical methods do not provide satisfactory results when applied to the determination of sediment deposition in small reservoirs. Small reservoir’s volumes do not exceed 5 × 106 m3 and their capacity-inflow ratio is less than 10%. Long-term silting measurements of three small reservoirs were used to evaluate the method described by Rahmanian and Banihashemi for predicting sediment distributions in small reservoirs. Rahmanian and Banihashemi stated that their model of distribution of sediment deposition in water reservoir works well for a long duration operation. In the presented study, the silting rate was used in order to determine the long duration operation. Silting rate is a quotient of volume of the sediment deposited in the reservoir and its original volume. It was stated that when the silting rate had reached 50%, the sediment deposition in the reservoir may be described by an empirical reservoir depth shape function (RDSF). Full article
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810 KiB  
Article
Fractal Dimension of Cohesive Sediment Flocs at Steady State under Seven Shear Flow Conditions
by Zhongfan Zhu, Jingshan Yu, Hongrui Wang, Jie Dou and Cheng Wang
Water 2015, 7(8), 4385-4408; https://doi.org/10.3390/w7084385 - 12 Aug 2015
Cited by 21 | Viewed by 5812
Abstract
The morphological properties of kaolin flocs were investigated in a Couette-flow experiment at the steady state under seven shear flow conditions (shear rates of 5.36, 9.17, 14, 24, 31, 41 and 53 s−1). These properties include a one-dimensional (1-D) fractal dimension [...] Read more.
The morphological properties of kaolin flocs were investigated in a Couette-flow experiment at the steady state under seven shear flow conditions (shear rates of 5.36, 9.17, 14, 24, 31, 41 and 53 s−1). These properties include a one-dimensional (1-D) fractal dimension (D1), a two-dimensional (2-D) fractal dimension (D2), a perimeter-based fractal dimension (Dpf) and an aspect ratio (AR). They were calculated based on the projected area (A), equivalent size, perimeter (P) and length (L) of the major axis of the floc determined through sample observation and an image analysis system. The parameter D2, which characterizes the relationship between the projected area and the length of the major axis using a power function, , increased from 1.73 ± 0.03, 1.72 ± 0.03, and 1.75 ± 0.04 in the low shear rate group (G = 5.36, 9.17, and 14 s−1) to 1.92 ± 0.03, 1.82 ± 0.02, 1.85 ± 0.02, and 1.81 ± 0.02 in the high shear rate group (24, 31, 41 and 53 s−1), respectively. The parameter D1 characterizes the relationship between the perimeter and length of the major axis by the function and decreased from 1.52 ± 0.02, 1.48 ± 0.02, 1.55 ± 0.02, and 1.63 ± 0.02 in the low shear group (5.36, 9.17, 14 and 24 s−1) to 1.45 ± 0.02, 1.39 ± 0.02, and 1.39 ± 0.02 in the high shear group (31, 41 and 53 s−1), respectively. The results indicate that with increasing shear rates, the flocs become less elongated and that their boundary lines become tighter and more regular, caused by more breakages and possible restructurings of the flocs. The parameter Dpf, which is related to the perimeter and the projected area through the function , decreased as the shear rate increased almost linearly. The parameter AR, which is the ratio of the length of the major axis and equivalent diameter, decreased from 1.56, 1.59, 1.53 and 1.51 in the low shear rate group to 1.43, 1.47 and 1.48 in the high shear rate group. These changes in Dpf and AR show that the flocs become less convoluted and more symmetrical and that their boundaries become smoother and more regular in the high shear rate group than in the low shear rate group due to breakage and possible restructuring processes. To assess the effects of electrolyte and sediment concentration, 0.1 mol/L calcium chloride (CaCl2) and initial sediment concentration from 7.87 × 10−5 to 1.57 × 10−5 were used in this preliminary study. The addition of electrolyte and increasing sediment concentration could produce more symmetrical flocs with less convoluted and simpler boundaries. In addition, some new information on the temporal variation of the median size of the flocs during the flocculation process is presented. Full article
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7198 KiB  
Article
Warning Model for Shallow Landslides Induced by Extreme Rainfall
by Lien-Kwei Chien, Chia-Feng Hsu and Li-Chung Yin
Water 2015, 7(8), 4362-4384; https://doi.org/10.3390/w7084362 - 11 Aug 2015
Cited by 17 | Viewed by 5705
Abstract
In this study, the geophysical properties of the landslide-prone catchment of the Gaoping River in Taiwan were investigated using zones based on landslide history in conjunction with landslide analysis using a deterministic approach based on the TRIGRS (Transient Rainfall Infiltration and Grid-based Regional [...] Read more.
In this study, the geophysical properties of the landslide-prone catchment of the Gaoping River in Taiwan were investigated using zones based on landslide history in conjunction with landslide analysis using a deterministic approach based on the TRIGRS (Transient Rainfall Infiltration and Grid-based Regional Slope-Stability) model. Typhoon Morakot in 2009 was selected as a simulation scenario to calibrate the combination of geophysical parameters in each zone before analyzing changes in the factor of safety (FS). Considering the amount of response time required for typhoons, suitable FS thresholds for landslide warnings are proposed for each town in the catchment area. Typhoon Fanapi of 2010 was used as a test scenario to verify the applicability of the FS as well as the efficacy of the cumulative rainfall thresholds derived in this study. Finally, the amount of response time provided by the FS thresholds in cases of yellow and red alerts was determined. All five of the landslide events reported by the Soil and Water Conservation Bureau were listed among the unstable sites identified in the proposed model, thereby demonstrating its effectiveness and accuracy in determining unstable areas and areas that require evacuation. These cumulative rainfall thresholds provide a valuable reference to guide disaster prevention authorities in the issuance of yellow and red alerts with the ability to reduce losses and save lives. Full article
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2612 KiB  
Article
Spatiotemporal Distribution of Soil Moisture and Salinity in the Taklimakan Desert Highway Shelterbelt
by Yuan Huang, Yongdong Wang, Ying Zhao, Xinwen Xu, Jianguo Zhang and Congjuan Li
Water 2015, 7(8), 4343-4361; https://doi.org/10.3390/w7084343 - 6 Aug 2015
Cited by 18 | Viewed by 6376
Abstract
Salinization and secondary salinization often appear after irrigation with saline water. The Taklimakan Desert Highway Shelterbelt has been irrigated with saline ground water for more than ten years; however, soil salinity in the shelterbelt has not been evaluated. The objective of this study [...] Read more.
Salinization and secondary salinization often appear after irrigation with saline water. The Taklimakan Desert Highway Shelterbelt has been irrigated with saline ground water for more than ten years; however, soil salinity in the shelterbelt has not been evaluated. The objective of this study was to analyze the spatial and temporal distribution of soil moisture and salinity in the shelterbelt system. Using a non-uniform grid method, soil samples were collected every two days during one ten-day irrigation cycle in July 2014 and one day in spring, summer, and autumn. The results indicated that soil moisture declined linearly with time during the irrigation cycle. Soil moisture was greatest in the southern and eastern sections of the study area. In contrast to soil moisture, soil electrical conductivity increased from 2 to 6 days after irrigation, and then gradually decreased from 6 to 8 days after irrigation. Soil moisture was the greatest in spring and the least in summer. In contrast, soil salinity increased from spring to autumn. Long time drip-irrigation with saline groundwater increased soil salinity slightly. The soil salt content was closely associated with soil texture. The current soil salt content did not affect plant growth, however, the soil in the shelterbelt should be continuously monitored to prevent salinization in the future. Full article
(This article belongs to the Special Issue Water Resources Assessment and Management in Drylands)
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2893 KiB  
Article
A New Spatiotemporal Risk Index for Heavy Metals: Application in Cyprus
by Christos G. Karydas, Ourania Tzoraki and Panos Panagos
Water 2015, 7(8), 4323-4342; https://doi.org/10.3390/w7084323 - 5 Aug 2015
Cited by 21 | Viewed by 8139
Abstract
The main aim of this research was to improve risk mapping of heavy metals by taking account of erosion effects. A new spatiotemporal index, namely the G2met index, is introduced, with integration of pre-existing methodologies (Hakanson, EPM, and G2). The G2met [...] Read more.
The main aim of this research was to improve risk mapping of heavy metals by taking account of erosion effects. A new spatiotemporal index, namely the G2met index, is introduced, with integration of pre-existing methodologies (Hakanson, EPM, and G2). The G2met index is depicted as a series of risk maps for each heavy metal on a month-time step. The southern part of Cyprus Island was selected as a study area. Concentration of major heavy metals was extracted with soil sampling in a grid of 5350 sites. Rainfall, vegetation, soil, land use, topographic, and hydrologic data were collected from existing European or global databases (WorldClim, BioBar, REDES, ESDAC, CORINE, ASTER GDEM, and USGS). A large number of regional-scale risk maps (with 500-m cell size) were created: one for each heavy metal and totally per month and annually; in addition, choropleth maps in terms of statistics per river basin were produced for every metal. Generally, the G2met maps resulted in different spatial patterns in comparison to those depicted by the Hakanson index alone. Full article
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900 KiB  
Article
Evaluating Groundwater Management Sustainability under Limited Data Availability in Semiarid Zones
by Javier Senent-Aparicio, Julio Pérez-Sánchez, José Luis García-Aróstegui, Alicia Bielsa-Artero and Juan Carlos Domingo-Pinillos
Water 2015, 7(8), 4305-4322; https://doi.org/10.3390/w7084305 - 5 Aug 2015
Cited by 27 | Viewed by 6680
Abstract
In recent years, many researchers have devoted their efforts to finding an objective measurement of sustainability by developing evaluation tools based on sustainability indices. These indexes not only reveal the current state of water resources in a given area but also contribute to [...] Read more.
In recent years, many researchers have devoted their efforts to finding an objective measurement of sustainability by developing evaluation tools based on sustainability indices. These indexes not only reveal the current state of water resources in a given area but also contribute to the development and implementation of effective sustainable water management and decision-making. The great disadvantage of these indices is that for proper application, a number of variables are necessary and they are usually not available in data-scarce aquifers. This study was designed to evaluate sustainability in groundwater resource management in an aquifer in a semiarid zone, using readily available parameters and under a pressure-state-response framework. This methodology has been applied to an aquifer in Southeast Spain with satisfactory results, since the indicators that were evaluated reflect the two main problems that hinder sustainable resource management: the contamination of groundwater by intensive local farming; and the need for external inputs from other basins to alleviate water stress. Therefore, the methodology used can be replicated in other areas with similar characteristics to those of the case study. Full article
(This article belongs to the Special Issue Sustainable Water Management and Decision Making under limited Data Availability)
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1581 KiB  
Article
Modeling of Breaching Due to Overtopping Flow and Waves Based on Coupled Flow and Sediment Transport
by Zhiguo He, Peng Hu, Liang Zhao, Gangfeng Wu and Thomas Pähtz
Water 2015, 7(8), 4283-4304; https://doi.org/10.3390/w7084283 - 5 Aug 2015
Cited by 11 | Viewed by 6189
Abstract
Breaching of earthen or sandy dams/dunes by overtopping flow and waves is a complicated process with strong, unsteady flow, high sediment transport, and rapid bed changes in which the interactions between flow and morphology should not be ignored. This study presents a depth-averaged [...] Read more.
Breaching of earthen or sandy dams/dunes by overtopping flow and waves is a complicated process with strong, unsteady flow, high sediment transport, and rapid bed changes in which the interactions between flow and morphology should not be ignored. This study presents a depth-averaged two-dimensional (2D) coupled flow and sediment transport model to investigate the flow and breaching processes with and without waves. Bed change and variable flow density are included in the flow continuity and momentum equations to consider the impacts of sediment transport. The model adopts the non-equilibrium approach for total-load sediment transport and specifies different repose angles to handle non-cohesive embankment slope avalanching. The equations are solved using an explicit finite volume method on a rectangular grid with the improved Godunov-type central upwind scheme and the nonnegative reconstruction of the water depth method to handle mixed-regime flows near the breach. The model has been tested against two sets of experimental data which show that it well simulates the flow characteristics, bed changes, and sediment transport. It is then applied to analyze flow and morphologic changes by overtopping flow with and without waves. The simulated bed change and breach cross-section shape show a significant difference if waves are considered. Erosion by flow without waves mainly occurs at the breach and is dominated by vertical erosion at the initial stage followed by the lateral erosion. With waves, the flow overtops the entire length of the dune to cause faster erosion along the entire length. Erosion mainly takes place at the upper layer at the initial stage and gradually accelerates as the height of the dune reduces and flow discharge increases, which indicates the simulated results with waves shall be further verified by physical experimental evidence. Full article
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192 KiB  
Communication
Influence of Policy Making in the Profitability of Forage Production Irrigated with Reclaimed Water
by María Del Pino Palacios-Diaz, Vanessa Mendoza-Grimón and Alberto Del Villar Garcia
Water 2015, 7(8), 4274-4282; https://doi.org/10.3390/w7084274 - 4 Aug 2015
Cited by 5 | Viewed by 4083
Abstract
The limited availability of water at low prices and the current scheme for specific supply arrangements (SSA/REA), both determined at the political level, explain that the goal of being self-sufficient in terms of forage consumption is currently unattainable in the Canaries. The “PFORCA” [...] Read more.
The limited availability of water at low prices and the current scheme for specific supply arrangements (SSA/REA), both determined at the political level, explain that the goal of being self-sufficient in terms of forage consumption is currently unattainable in the Canaries. The “PFORCA” Plan aims to counteract this reality and increase their level of self-sufficiency. The financial aid relating to the REA reduces the amount payable for the imported fodder (annual 83,000 t) versus local product, which influences the decision making by farmers. According to calculations, performed by reusing the water instead of discharging, Maralfalfa production could be competitive against imports, being financially viable with water prices in a range of 0.20–0.30 €/m3 (prices perfectly acceptable for reclaimed water with low levels of treatment, but fulfilling requirements reuse of Spanish law, RD 1620/2007). The economic contribution of forage crops could represent the creation of 640 new jobs, the enhancement of land currently abandoned, plus an increase in Gross Domestic Product (GDP) of the archipelago on more than 23 million € (M€), product of the substitution of imports by local production. Also, it would help to save the REA’s aid (6 M€). Full article
(This article belongs to the Special Issue Study, Development and Management of Water in Volcanic Areas)
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872 KiB  
Article
Model Spin-Up Behavior for Wet and Dry Basins: A Case Study Using the Xinanjiang Model
by Mohammad Mahfuzur Rahman and Minjiao Lu
Water 2015, 7(8), 4256-4273; https://doi.org/10.3390/w7084256 - 4 Aug 2015
Cited by 20 | Viewed by 6059
Abstract
Model spin-up is an adjustment process where its internal stores move from an initial state of unusual conditions to one of equilibrium. Model outputs during this spin-up process are often unrealistic and misleading. This study investigates some primary factors affecting spin-up time using [...] Read more.
Model spin-up is an adjustment process where its internal stores move from an initial state of unusual conditions to one of equilibrium. Model outputs during this spin-up process are often unrealistic and misleading. This study investigates some primary factors affecting spin-up time using the Xinanjiang model for 22 river basins throughout the United States. A 10-year recursive simulation with three data sets indicates that time required for model equilibrium is not only a function of initial conditions, but also is affected by input data sets (precipitation and evaporation). The model requires less time to be equilibrated under wetter initial conditions (lowest under saturated initial condition). Moreover, model spin-up time shows distinct variations with the dryness of the input data sets. Analysis suggests that wet basins (ratio of evaporation over precipitation <0.9) require less time (55 days) for model equilibrium in comparison to that of dry basins (298 days). The spin-up time displayed an exponential relationship with the basin aridity index (r2 = 0.85). This relationship could provide a way to predict the maximum model spin-up time using the precipitation and evaporation information only. Predicting maximum model spin-up time based on this relationship could be valuable to reduce uncertainty, particularly under data scarce situations. Full article
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1109 KiB  
Communication
Traceability of pH to the Mole
by Maria Filomena Camões and Bárbara Anes
Water 2015, 7(8), 4247-4255; https://doi.org/10.3390/w7084247 - 3 Aug 2015
Cited by 7 | Viewed by 6129
Abstract
Free acidity of aqueous solutions was initially defined in 1909 by Søren Peter Lauritz Sørensen as pH = −lgcH+ (c/mol·dm−3 or m/mol·kg−1 of the free hydrogen ions in solution, H+) soon (1910) was changed [...] Read more.
Free acidity of aqueous solutions was initially defined in 1909 by Søren Peter Lauritz Sørensen as pH = −lgcH+ (c/mol·dm−3 or m/mol·kg−1 of the free hydrogen ions in solution, H+) soon (1910) was changed to pH = paH+ = −lgaH+, integrating the new concepts of activity, ai and activity coefficient γi, for the ionic species i under concern, H+ in this case; it is ai = −lg(miγi). Since individual ions do not exist alone in solution, primary pH values cannot be assigned solely by experimental measurements, requiring extra thermodynamic model assumptions for the activity coefficient, γH+, which has put pH in a unique situation of not being fully traceable to the International System of Units (SI). Also the concept of activity is often not felt to be as perceptible as that of concentration which may present difficulties, namely with the interpretation of data. pH measurements on unknown samples rely on calibration of the measuring setup with adequate reference pH buffers. In this work, the assignment of pH values to buffers closely matching the samples, e.g., seawater, is revisited. An approach is presented to assess the quantity pmH+ = −lgmH+ profiting from the fact that, contrary to single ion activity coefficients, mean activity coefficients, can be assessed based on experimentally assessed quantities alone, γExp ±, thus ensuring traceability to the mole, the SI base unit for amount of substance. Compatibility between γExp ± and mean activity coefficient calculated by means of Pitzer model equations, γPtz ±, validates the model for its intended use. Full article
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1354 KiB  
Article
Daily Reservoir Runoff Forecasting Method Using Artificial Neural Network Based on Quantum-behaved Particle Swarm Optimization
by Chun-tian Cheng, Wen-jing Niu, Zhong-kai Feng, Jian-jian Shen and Kwok-wing Chau
Water 2015, 7(8), 4232-4246; https://doi.org/10.3390/w7084232 - 31 Jul 2015
Cited by 82 | Viewed by 8418
Abstract
Accurate daily runoff forecasting is of great significance for the operation control of hydropower station and power grid. Conventional methods including rainfall-runoff models and statistical techniques usually rely on a number of assumptions, leading to some deviation from the exact results. Artificial neural [...] Read more.
Accurate daily runoff forecasting is of great significance for the operation control of hydropower station and power grid. Conventional methods including rainfall-runoff models and statistical techniques usually rely on a number of assumptions, leading to some deviation from the exact results. Artificial neural network (ANN) has the advantages of high fault-tolerance, strong nonlinear mapping and learning ability, which provides an effective method for the daily runoff forecasting. However, its training has certain drawbacks such as time-consuming, slow learning speed and easily falling into local optimum, which cannot be ignored in the real world application. In order to overcome the disadvantages of ANN model, the artificial neural network model based on quantum-behaved particle swarm optimization (QPSO), ANN-QPSO for short, is presented for the daily runoff forecasting in this paper, where QPSO was employed to select the synaptic weights and thresholds of ANN, while ANN was used for the prediction. The proposed model can combine the advantages of both QPSO and ANN to enhance the generalization performance of the forecasting model. The methodology is assessed by using the daily runoff data of Hongjiadu reservoir in southeast Guizhou province of China from 2006 to 2014. The results demonstrate that the proposed approach achieves much better forecast accuracy than the basic ANN model, and the QPSO algorithm is an alternative training technique for the ANN parameters selection. Full article
(This article belongs to the Special Issue Use of Meta-Heuristic Techniques in Rainfall-Runoff Modelling)
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954 KiB  
Article
Transferable Principles for Managing the Nexus: Lessons from Historical Global Water Modelling of Central Asia
by Joseph H. A. Guillaume, Matti Kummu, Stephanie Eisner and Olli Varis
Water 2015, 7(8), 4200-4231; https://doi.org/10.3390/w7084200 - 31 Jul 2015
Cited by 37 | Viewed by 9586
Abstract
The complex relationships within the water-energy-food security nexus tend to be place-specific, increasing the importance of identifying transferable principles to facilitate implementation of a nexus approach. This paper aims to contribute transferable principles by using global model data and concepts to illustrate and [...] Read more.
The complex relationships within the water-energy-food security nexus tend to be place-specific, increasing the importance of identifying transferable principles to facilitate implementation of a nexus approach. This paper aims to contribute transferable principles by using global model data and concepts to illustrate and analyze the water history of Central Asia. This approach builds on extensive literature about Central Asia and global change as well as recent advances in global water modeling. Decadal water availability and sectorial water consumption time series are presented for the whole 20th century, along with monthly changes in discharge attributable to human influences. Concepts from resilience and socio-ecological system theory are used to interpret the results and identify five principles relevant to managing the transboundary nexus: (1) the subsystems included/excluded from the nexus are case-specific and should be consciously scrutinized; (2) consensus is needed on what boundaries can acceptably be crossed within the nexus; (3) there is a need to understand how reducing trade-offs will modify system dependencies; (4) global stakeholders have both a responsibility and right to contribute to the shaping of the nexus; (5) combining data with global and local perspectives can help to enhance transferability and understanding of shared problems in our globalized world. Full article
(This article belongs to the Special Issue Water-Energy-Food Nexus in Large Asian River Basins)
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9343 KiB  
Article
Reconstruction of Lake Level Changes of Groundwater-Fed Lakes in Northeastern Germany Using RapidEye Time Series
by Iris Heine, Peter Stüve, Birgit Kleinschmit and Sibylle Itzerott
Water 2015, 7(8), 4175-4199; https://doi.org/10.3390/w7084175 - 31 Jul 2015
Cited by 16 | Viewed by 5904
Abstract
Groundwater-fed lakes in northeastern Germany are characterized by significant lake level changes, but for only a few lakes are in situ water level measurements available. In this study, we test the potential of RapidEye satellite images for indirectly reconstructing lake level changes. The [...] Read more.
Groundwater-fed lakes in northeastern Germany are characterized by significant lake level changes, but for only a few lakes are in situ water level measurements available. In this study, we test the potential of RapidEye satellite images for indirectly reconstructing lake level changes. The lake levels are derived by intersecting water-land borders with a high-resolution digital elevation model (DEM). Based on Lake Fürstenseer (LF), we define requirements and limitations of the method. Water-land borders were extracted automatically from the 37 RapidEye images available for the period between 2009 and 2014. Otsu’s threshold was used for the NIR band and for the normalized difference water index (NDWI). The results were validated with in situ gauging, contour lines from the DEM, and in situ Differential Global Positioning System (DGPS) measurements of the shoreline. Using an ideal shoreline subset, the lake levels could be reconstructed with decimeter accuracy using the NIR water-land border, but the levels were systematically underestimated by 0–20 cm. The accuracy of the reconstructed lake level retrieval strongly depends on the precision of the water-land border retrieval, on the accuracy of the DEM, and on the lake level itself. A clear shift of the water-land border with increasing lake level is also essential for the unambiguous reconstruction of different levels. This shift needs to be several times larger than the pixel size. The biggest challenges for lake level reconstruction are the presence of vegetation at the shorelines, the quality of the topographic data in the underwater area, the slope of the shoreline, and shadows in combination with low solar angles. Full article
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287 KiB  
Article
Comparison of the Physical Properties of Showers that the Satisfaction of Shower Feeling among Users in Three Asian Countries
by Minami Okamoto, Ryohei Yaita, Minoru Sato, Masayoshi Kamijo, Kanako Toyosada, Yasutoshi Shimizu, Kyosuke Sakaue, Wan-Ju Liao, Meng-Chieh Lee and Cheng-Li Cheng
Water 2015, 7(8), 4161-4174; https://doi.org/10.3390/w7084161 - 30 Jul 2015
Cited by 10 | Viewed by 5389
Abstract
The purpose of this study was to construct a scheme that makes it possible to compare the relationship between water usage, satisfaction, and physical properties in three countries. The physical properties of the shower were measured using physical properties testing apparatus of water-saving [...] Read more.
The purpose of this study was to construct a scheme that makes it possible to compare the relationship between water usage, satisfaction, and physical properties in three countries. The physical properties of the shower were measured using physical properties testing apparatus of water-saving standard or scheme for showerheads issued in several water-saving countries and data for users satisfaction evaluation was acquired through bathing experiments. In this paper, we analyzed the result from Taiwanese and Vietnamese individuals to compare them to of Japanese subjects analyzed in the previous study. We compared the physical properties of showers assessed low in satisfaction by Taiwanese, Vietnamese and Japanese subjects. It was assumed that spray pattern tends to decrease satisfaction when the water volume ratio within 100 mm and 150 mm of a measuring device is located a 450 mm distance from the showerhead is low, and that, because all three countries showed the same value, it was imagined that there were no differences in the water volume ratio of high-satisfaction showerheads among three countries. On the other hand, the values of Spray Force-per-Hole, Temperature Drop, and Spray Angle were different among three countries. We speculated that these differences are affected respectively by ethnic differences in pain tolerance, thermoregulatory response and bathing habit. Full article
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661 KiB  
Article
Daily Runoff Forecasting Model Based on ANN and Data Preprocessing Techniques
by Yun Wang, Shenglian Guo, Lihua Xiong, Pan Liu and Dedi Liu
Water 2015, 7(8), 4144-4160; https://doi.org/10.3390/w7084144 - 28 Jul 2015
Cited by 21 | Viewed by 6413
Abstract
There are many models that have been used to simulate the rainfall-runoff relationship. The artificial neural network (ANN) model was selected to investigate an approach of improving daily runoff forecasting accuracy in terms of data preprocessing. Singular spectrum analysis (SSA) as one data [...] Read more.
There are many models that have been used to simulate the rainfall-runoff relationship. The artificial neural network (ANN) model was selected to investigate an approach of improving daily runoff forecasting accuracy in terms of data preprocessing. Singular spectrum analysis (SSA) as one data preprocessing technique was adopted to deal with the model inputs and the SSA-ANN model was developed. The proposed model was compared with the original ANN model without data preprocessing and a nonlinear perturbation model (NLPM) based on ANN, i.e., the NLPM-ANN model. Eight watersheds were selected for calibrating and testing these models. Comparative study shows that the learning and training ability of ANN models can be improved by SSA and NLPM techniques significantly, and the performance of the SSA-ANN model is much better than the NLPM-ANN model, with high foresting accuracy. The SSA-ANN1 model, which only considers rainfall as model input, was compared with the SSA-ANN2 model, which considers both rainfall and previous runoff as model inputs. It is shown that the Nash-Sutcliffe criterion of the SSA-ANN2 model is much higher than that of the SSA-ANN1 model, which means that the proper selection of previous runoff data as rainfall-runoff model inputs can significantly improve model performance since they usually are highly auto-correlated. Full article
(This article belongs to the Special Issue Use of Meta-Heuristic Techniques in Rainfall-Runoff Modelling)
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2824 KiB  
Article
Analysis of Urban Drainage Networks Using Gibbs’ Model: A Case Study in Seoul, South Korea
by Yongwon Seo, Junshik Hwang and Seong Jin Noh
Water 2015, 7(8), 4129-4143; https://doi.org/10.3390/w7084129 - 28 Jul 2015
Cited by 6 | Viewed by 7452
Abstract
Drainage networks are essential compartments in an urban infrastructure system for the efficient collection and prompt drainage of flood water. In addition to the advances in numerical techniques on urban flood simulation, the topological characteristics of urban drainage networks and their impacts on [...] Read more.
Drainage networks are essential compartments in an urban infrastructure system for the efficient collection and prompt drainage of flood water. In addition to the advances in numerical techniques on urban flood simulation, the topological characteristics of urban drainage networks and their impacts on flooding have not been investigated thoroughly despite their importance. This study evaluated the urban drainage networks in Seoul, South Korea, in terms of the network configuration and its implication for peak flows and flood mitigation. Gibbs’ model was used to analyze the network configuration of 31 urban catchments with various slope ranges. The results showed that urban drainage networks can be less efficient than river in nature in terms of the drainage time, which is counter-intuitive. On the other hand, the analysis showed that efficient networks have risks of flood concentration and, hence, increase potential flood risks. This study showed that efficient networks tend to have higher peak flows at the outlet and vice versa. Therefore, an alternative drainage network layout, which is less efficient and more sinuous, was introduced and it resulted in reduced peak flows and flooding. This result shows managing a proper drainage network layout can contribute to flood mitigation in urban catchments. Full article
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2904 KiB  
Article
Seawater and Freshwater Circulations through Coastal Forested Wetlands on a Caribbean Island
by Luc Lambs, Félix Bompy, Daniel Imbert, Dov Corenblit and Maguy Dulormne
Water 2015, 7(8), 4108-4128; https://doi.org/10.3390/w7084108 - 27 Jul 2015
Cited by 14 | Viewed by 7288
Abstract
Structure and composition of coastal forested wetlands are mainly controlled by local topography and soil salinity. Hydrology plays a major role in relation with tides, seaward, and freshwater inputs, landward. We report here the results of a two-year study undertaken in a coastal [...] Read more.
Structure and composition of coastal forested wetlands are mainly controlled by local topography and soil salinity. Hydrology plays a major role in relation with tides, seaward, and freshwater inputs, landward. We report here the results of a two-year study undertaken in a coastal plain of the Guadeloupe archipelago (FWI). As elsewhere in the Caribbean islands, the study area is characterized by a micro-tidal regime and a highly seasonal climate. This work aimed at understanding groundwater dynamics and origin (seawater/freshwater) both at ecosystems and stand levels. These hydrological processes were assessed through 18O/16O and 2H/1H isotopic analyses, and from monthly monitoring of water level and soil salinity at five study sites located in mangrove (3) and swamp forest (2). Our results highlight the importance of freshwater budget imbalance during low rainfall periods. Sustained and/or delayed dry seasons cause soil salinity to rise at the mangrove/swamp forest ecotone. As current models on climate change project decreasing rainfall amounts over the inner Caribbean region, one may expect for this area an inland progression of the mangrove forest to the expense of the nearby swamp forest. Full article
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2266 KiB  
Article
Uncertainty in Various Habitat Suitability Models and Its Impact on Habitat Suitability Estimates for Fish
by Yu-Pin Lin, Wei-Chih Lin and Wei-Yao Wu
Water 2015, 7(8), 4088-4107; https://doi.org/10.3390/w7084088 - 27 Jul 2015
Cited by 21 | Viewed by 7170
Abstract
Species distribution models (SDMs) are extensively used to project habitat suitability of species in stream ecological studies. Owing to complex sources of uncertainty, such models may yield projections with varying degrees of uncertainty. To better understand projected spatial distributions and the variability between [...] Read more.
Species distribution models (SDMs) are extensively used to project habitat suitability of species in stream ecological studies. Owing to complex sources of uncertainty, such models may yield projections with varying degrees of uncertainty. To better understand projected spatial distributions and the variability between habitat suitability projections, this study uses five SDMs that are based on the outputs of a two-dimensional hydraulic model to project the suitability of habitats and to evaluate the degree of variability originating from both differing model types and the split-sample procedure. The habitat suitability index (HSI) of each species is based on two stream flow variables, including current velocity (V), water depth (D), as well as the heterogeneity of these flow conditions as quantified by the information entropy of V and D. The six SDM approaches used to project fish abundance, as represented by HSI, included two stochastic models: the generalized linear model (GLM) and the generalized additive model (GAM); as well as three machine learning models: the support vector machine (SVM), random forest (RF) and the artificial neural network (ANN), and an ensemble model (where the latter is the average of the preceding five models). The target species Sicyopterus japonicas was found to prefer habitats with high current velocities. The relationship between mesohabitat diversity and fish abundance was indicated by the trends in information entropy and weighted usable area (WUA) over the study area. This study proposes a method for quantifying habitat suitability, and for assessing the uncertainties in HSI and WUA that are introduced by the various SDMs and samples. This study also demonstrated both the merits of the ensemble modeling approach and the necessity of addressing model uncertainty. Full article
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1327 KiB  
Review
Urban Evolution: The Role of Water
by Sujay S. Kaushal, William H. McDowell, Wilfred M. Wollheim, Tamara A. Newcomer Johnson, Paul M. Mayer, Kenneth T. Belt and Michael J. Pennino
Water 2015, 7(8), 4063-4087; https://doi.org/10.3390/w7084063 - 27 Jul 2015
Cited by 73 | Viewed by 15818
Abstract
The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It [...] Read more.
The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It allows urban planning, management, and restoration to move beyond reactive management to predictive management based on past observations of consistent patterns. Here, we define and review a glossary of core concepts for studying urban evolution, which includes the mechanisms of urban selective pressure and urban adaptation. Urban selective pressure is an environmental or societal driver contributing to urban adaptation. Urban adaptation is the sequential process by which an urban structure, function, or services becomes more fitted to its changing environment or human choices. The role of water is vital to driving urban evolution as demonstrated by historical changes in drainage, sewage flows, hydrologic pulses, and long-term chemistry. In the current paper, we show how hydrologic traits evolve across successive generations of urban ecosystems via shifts in selective pressures and adaptations over time. We explore multiple empirical examples including evolving: (1) urban drainage from stream burial to stormwater management; (2) sewage flows and water quality in response to wastewater treatment; (3) amplification of hydrologic pulses due to the interaction between urbanization and climate variability; and (4) salinization and alkalinization of fresh water due to human inputs and accelerated weathering. Finally, we propose a new conceptual model for the evolution of urban waters from the Industrial Revolution to the present day based on empirical trends and historical information. Ultimately, we propose that water itself is a critical driver of urban evolution that forces urban adaptation, which transforms the structure, function, and services of urban landscapes, waterways, and civilizations over time. Full article
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295 KiB  
Article
Identifying the Physical Properties of Showers That Influence User Satisfaction to Aid in Developing Water-Saving Showers
by Minami Okamoto, Minoru Sato, Yoshihiko Shodai and Masayoshi Kamijo
Water 2015, 7(8), 4054-4062; https://doi.org/10.3390/w7084054 - 24 Jul 2015
Cited by 14 | Viewed by 5584
Abstract
This research was conducted with the goal of clarifying the required conditions of water-saving showerheads. In order to this, the research analyzes the mutual relationship between water usage flow, the level of satisfaction and the physical properties of spray of showerheads. The physical [...] Read more.
This research was conducted with the goal of clarifying the required conditions of water-saving showerheads. In order to this, the research analyzes the mutual relationship between water usage flow, the level of satisfaction and the physical properties of spray of showerheads. The physical properties of spray were measured using physical properties test apparatus of standard or scheme for water-saving showerheads issued in several water-saving countries, and satisfaction evaluation data was acquired through bathing experiments. The evaluated showerheads were separated into three groups according to usage water flow and the level of satisfaction. The relationships between usage water flow, the level of satisfaction and physical properties were compared. The results identified that Spray Force and Spray Force-per-Hole were physical properties that influence usage water flow. Spray force-per-hole, water volume ratio in Spray Patterns within φ 100 and φ 150, Temperature Drop and Spray Angle were identified as physical properties that influenced the level of satisfaction. The level of satisfaction and usage water flow has a spurious correlation through the physical properties of Spray Force-per-Hole and Temperature Drop. It is possible to improve the level of satisfaction independent of amount of water usage through designs that set an appropriate value for water volume ratio and Spray Angle for Spray Patterns within φ 100 and φ 150. Full article
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523 KiB  
Article
Simulation of Summer Hourly Stream Flow by Applying TOPMODEL and Two Routing Algorithms to the Sparsely Gauged Lhasa River Basin in China
by Dingzhi Peng, Ji Chen and Jing Fang
Water 2015, 7(8), 4041-4053; https://doi.org/10.3390/w7084041 - 23 Jul 2015
Cited by 14 | Viewed by 4741
Abstract
This paper develops a new routing algorithm for improving simulation capacity of physically-based hydrological models applied to sparsely-gauged river basins. The study area is the Lhasa River basin, a large plateau basin with an area of 26,225 km2 in southwest China. In [...] Read more.
This paper develops a new routing algorithm for improving simulation capacity of physically-based hydrological models applied to sparsely-gauged river basins. The study area is the Lhasa River basin, a large plateau basin with an area of 26,225 km2 in southwest China. In the basin, observations from three hydrological stations are available, and the observed hourly rainfall and summer stream flow data (12 June to 30 September) for the period of 1998–2000 obtained from the three stations were used. TOPMODEL, with its original routing algorithm, which is a distance-related delay function, was applied to the Lhasa River basin. To improve the routing algorithm using a unit hydrograph function and a linear reservoir method, this study proposed a new algorithm; the results revealed that the new algorithm improved the simulation of the variation of hourly stream flow. In addition, to evaluate the influence of rainfall spatial variation on runoff generation, observed rainfall series from the three gauges were used to simulate runoff individually, and it was found that there are significant differences among the three simulated hourly stream flow series. Full article
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