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Water, Volume 9, Issue 8 (August 2017)

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Cover Story (view full-size image) Excess sediment continues to be a major polluter of surface water with streambank erosion being a [...] Read more.
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Open AccessArticle
Application of a Double-Sided Chance-Constrained Integer Linear Program for Optimization of the Incremental Value of Ecosystem Services in Jilin Province, China
Water 2017, 9(8), 629; https://doi.org/10.3390/w9080629
Received: 27 June 2017 / Revised: 13 August 2017 / Accepted: 16 August 2017 / Published: 22 August 2017
Cited by 2 | Viewed by 1212 | PDF Full-text (2426 KB) | HTML Full-text | XML Full-text
Abstract
The Interconnected River System Network Project (IRSNP) is a significant water supply engineering project, which is capable of effectively utilizing flood resources to generate ecological value, by connecting 198 lakes and ponds in western Jilin, northeast China. In this article, an optimization research [...] Read more.
The Interconnected River System Network Project (IRSNP) is a significant water supply engineering project, which is capable of effectively utilizing flood resources to generate ecological value, by connecting 198 lakes and ponds in western Jilin, northeast China. In this article, an optimization research approach has been proposed to maximize the incremental value of IRSNP ecosystem services. A double-sided chance-constrained integer linear program (DCCILP) method has been proposed to support the optimization, which can deal with uncertainties presented as integers or random parameters that appear on both sides of the decision variable at the same time. The optimal scheme indicates that after rational optimization, the total incremental value of ecosystem services from the interconnected river system network project increased 22.25%, providing an increase in benefits of 3.26 × 109 ¥ compared to the original scheme. Most of the functional area is swamp wetland, which provides the greatest ecological benefits. Adjustment services increased obviously, implying that the optimization scheme prioritizes ecological benefits rather than supply and production services. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle
Estimation of Suspended Sediment Loads Using Copula Functions
Water 2017, 9(8), 628; https://doi.org/10.3390/w9080628
Received: 15 June 2017 / Revised: 2 August 2017 / Accepted: 17 August 2017 / Published: 22 August 2017
Cited by 5 | Viewed by 1611 | PDF Full-text (2949 KB) | HTML Full-text | XML Full-text
Abstract
Suspended sediment load (SSL) observations are usually less frequent than precipitation and river discharge measurements; therefore a reliable procedure is needed for the estimation of SSL. One year of precipitation, SSL, and discharge measurements at 20-min intervals were performed [...] Read more.
Suspended sediment load (SSL) observations are usually less frequent than precipitation and river discharge measurements; therefore a reliable procedure is needed for the estimation of SSL. One year of precipitation, SSL, and discharge measurements at 20-min intervals were performed at the Kuzlovec torrent in Slovenia. The Frank copula was selected to construct an event-based model using the following variables: precipitation sum (P), peak discharge (Q), and SSL. The idea was to estimate the SSL based on the measured P and Q. The proposed model was additionally tested using the daily data from the Gornja Radgona station on the Mura River, for which 29 years of data were available and where Khoudraji-Liebscher copulas were used. The estimated SSL values using the copula were compared with different regression models. The proposed copula model yielded meaningful SSL estimates. Some performance criteria and tests indicated that the copula model gives a better fit to the measured data than other tested methods. Full article
(This article belongs to the Special Issue Soil Erosion by Water)
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Open AccessArticle
Effectiveness of Runoff Control Legislation and Active, Beautiful, Clean (ABC) Waters Design Features in Singapore
Water 2017, 9(8), 627; https://doi.org/10.3390/w9080627
Received: 9 June 2017 / Revised: 7 August 2017 / Accepted: 10 August 2017 / Published: 22 August 2017
Cited by 2 | Viewed by 1652 | PDF Full-text (6544 KB) | HTML Full-text | XML Full-text
Abstract
Storm water management in Singapore has always been a challenge due to intense rainfall in a flat, low-lying and urbanised catchment. PUB’s (Singapore’s National Water Agency) recent runoff control regulation limits the runoff coefficient to 0.55 for developments larger than or equal to [...] Read more.
Storm water management in Singapore has always been a challenge due to intense rainfall in a flat, low-lying and urbanised catchment. PUB’s (Singapore’s National Water Agency) recent runoff control regulation limits the runoff coefficient to 0.55 for developments larger than or equal to 0.2 ha. The use of Active, Beautiful, Clean (ABC) Waters design features are encouraged to attain peak runoff reduction. Hence the paper focuses on (i) determining the actual hydrological response regime of Singapore using the relationship between runoff coefficient (C), land use and slope; and (ii) investigating the effectiveness of ABC Waters design features in delaying and reducing peak runoff using a modelling approach. Based on a Storm Water Management Model (SWMM) model and using elevation, land use and soil data as inputs, the peak C-values were obtained for 50 m × 50 m grid cells. The results show that for the same land use, the one with steeper slope resulted in a higher runoff coefficient. Simulations were carried out in two study areas, Green Walk District and Tengah Subcatchment, where ABC Waters design features (such as porous pavements, green roofs, rain gardens) and detention tanks were incorporated to reduce C-values. Results showed that peak C-values can be reduced to less than 0.55 after increasing the green areas and constructing detention facilities. Reduction in peak discharge (22% to 63%) and a delay in peak discharge by up to 30 min were also observed. Hence, it is recommended to consider the relationship between slope and land use while determining runoff coefficients; and to incorporate ABC Waters design features in urban design to reduce the peak flow and runoff coefficient (C). Full article
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Open AccessArticle
Forecasting of Industrial Water Demand Using Case-Based Reasoning—A Case Study in Zhangye City, China
Water 2017, 9(8), 626; https://doi.org/10.3390/w9080626
Received: 30 June 2017 / Revised: 3 August 2017 / Accepted: 18 August 2017 / Published: 22 August 2017
Cited by 2 | Viewed by 2780 | PDF Full-text (2804 KB) | HTML Full-text | XML Full-text
Abstract
Forecasting the industrial water demand accurately is crucial for sustainable water resource management. This study investigates industrial water demand forecasting by case-based reasoning (CBR) in an arid area, with a case study of Zhangye, China. We constructed a case base with 420 original [...] Read more.
Forecasting the industrial water demand accurately is crucial for sustainable water resource management. This study investigates industrial water demand forecasting by case-based reasoning (CBR) in an arid area, with a case study of Zhangye, China. We constructed a case base with 420 original cases of 28 cities in China, extracted six attributes of the industrial water demand, and employed a back propagation neural network (BPN) to weight each attribute, as well as the grey incidence analysis (GIA) to calculate the similarities between target case and original cases. The forecasting values were calculated by weighted similarities. The results show that the industrial water demand of Zhangye in 2030, which is the t arget case, will reach 11.9 million tons. There are 10 original cases which have relatively high similarities to the target case. Furthermore, the case of Yinchuan, 2010, has the largest similarity, followed by Yinchuan, 2009, and Urumqi, 2009. We also made a comparison experiment in which case-based reasoning is more accurate than the grey forecast model and BPN in water demand forecasting. It is expected that the results of this study will provide references to water resources management and planning. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle
Approximate Explicit Solution to the Green-Ampt Infiltration Model for Estimating Wetting Front Depth
Water 2017, 9(8), 609; https://doi.org/10.3390/w9080609
Received: 10 July 2017 / Revised: 4 August 2017 / Accepted: 9 August 2017 / Published: 22 August 2017
Cited by 3 | Viewed by 1162 | PDF Full-text (2175 KB) | HTML Full-text | XML Full-text
Abstract
Obtaining reliable information on the wetting front depth of soil is beneficial to the understanding of one-dimensional (1D) vertical infiltration under border irrigation. This paper presents an approximate explicit solution to the Green-Ampt (GA) infiltration model for estimating the wetting front depth. Moreover, [...] Read more.
Obtaining reliable information on the wetting front depth of soil is beneficial to the understanding of one-dimensional (1D) vertical infiltration under border irrigation. This paper presents an approximate explicit solution to the Green-Ampt (GA) infiltration model for estimating the wetting front depth. Moreover, the model proposed in this study, the GA model, the Ali model, and the Stone model were validated and evaluated using laboratory experimental data and HYDRUS-1D simulation. Statistical comparisons (root mean square error-RMSE, mean absolute percent relative error-MAPRE, and percent bias-PB) of the estimated data with the measured and simulated data were conducted. The models were ranked on the basis of their overall performance index (OPI). The results demonstrated that all four models can be used to estimate the wetting front depth of 1D vertical infiltration for a wide range of soil textures; the proposed model provided the most accurate result. According to comparisons of the estimated values with the measured and simulated values, the maximum RMSE, MAPRE, and PB were 1.74 cm, 6.92%, and −6.74%, respectively, for the proposed model. On the basis of the OPI, the optimal model was the proposed model, followed by the Ali, GA, and Stone models. Full article
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Open AccessArticle
Hydrogeochemistry of Shallow Groundwater in a Karst Aquifer System of Bijie City, Guizhou Province
Water 2017, 9(8), 625; https://doi.org/10.3390/w9080625
Received: 29 July 2017 / Revised: 15 August 2017 / Accepted: 16 August 2017 / Published: 21 August 2017
Cited by 10 | Viewed by 1543 | PDF Full-text (2332 KB) | HTML Full-text | XML Full-text
Abstract
In this study, the major chemical compositions of 159 shallow groundwater samples incorporated saturation index (SI) and Principal Component Analysis (PCA) were employed to evaluate the mainly geochemical processes that control the hydrogeochemical evolution of groundwater in a typical karst area, Bijie city, [...] Read more.
In this study, the major chemical compositions of 159 shallow groundwater samples incorporated saturation index (SI) and Principal Component Analysis (PCA) were employed to evaluate the mainly geochemical processes that control the hydrogeochemical evolution of groundwater in a typical karst area, Bijie city, Guizhou Province. The groundwater samples in this study area were dominated of HCO3-Ca, HCO3-Ca-Mg, and HCO3-SO4-Ca types. The PCA suggested that four principal components could explain 88.85% of the total variance of 10 parameters, indicating that the hydrogeochemical evolution of groundwater was mainly controlled by the dissolution/precipitation of carbonates, gypsum, and halite minerals, cation exchange, and anthropogenic activities. To be specific, the enrichment of Ca2+, Mg2+, HCO3 and SO42− in groundwater were primarily affected by the dissolution of dolomite and gypsum minerals, and the role of calcite dissolution was relatively weaker because most groundwater samples were saturated with respect to calcite. Besides, cation exchange was another factor that may affect the concentration of Ca2+ and Mg2+ in groundwater, and the concentration of SO42− can also be influenced by coal mining activity. In addition, the concentrations of Na+ and Cl in groundwater were likely influenced by the dissolution of halite, cation exchange, and human activities. Full article
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Open AccessArticle
Diel and Seasonal Patterns in Continuously Monitored Water Quality at Fixed Sites in Two Adjacent Embayments of the Tidal Freshwater Potomac River
Water 2017, 9(8), 624; https://doi.org/10.3390/w9080624
Received: 1 June 2017 / Revised: 14 August 2017 / Accepted: 15 August 2017 / Published: 21 August 2017
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Abstract
Water quality patterns in two adjacent embayments of the tidal freshwater Potomac River were compared using continuously monitored data. The two embayments, the tidal Occoquan and Gunston Cove, are shallow embayments fed by tributaries which vary in their watershed attributes. The tidal Occoquan [...] Read more.
Water quality patterns in two adjacent embayments of the tidal freshwater Potomac River were compared using continuously monitored data. The two embayments, the tidal Occoquan and Gunston Cove, are shallow embayments fed by tributaries which vary in their watershed attributes. The tidal Occoquan has a larger watershed and a dam just upstream from the head of tide whereas Gunston Cove has a large wastewater treatment plant just upstream of the embayment. Water temperature, specific conductance, dissolved oxygen (DO), and pH were collected at 15 min intervals at representative locations in the two embayments from April through November of 2012. Mean daily values of water quality variables exhibited similar seasonal patterns at both sites which were related to seasonal patterns of forcing functions such as temperature, light and freshwater inflows. Three two-week intervals were examined in great detail. During a mid-summer period of stable conditions and low flow, both embayments exhibited strong and consistent diel (light cycle-based) periodicity in temperature, DO, and pH. Specific conductance exhibited semi-diel (tidal cycle-based) periodicity. The two other two-week intervals were punctuated by substantial flow events which resulted in major changes in daily mean values and disruptions to the typical diel or semi-diel cycles. The large rainfall event related to Hurricane Sandy caused a major disruption in diel and semi-diel cycles. Some cycles were quickly re-established and others took a week or more. The two embayments exhibited similar behavior in most aspects. Site-specific factors such as differences in the frequency and magnitude of tributary flow pulses and the presence of treated sewage discharge at Gunston Cove helped explain some of the differences observed between the two embayments. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle
Estimation of Water Demand in Water Distribution Systems Using Particle Swarm Optimization
Water 2017, 9(8), 593; https://doi.org/10.3390/w9080593
Received: 1 July 2017 / Revised: 25 July 2017 / Accepted: 3 August 2017 / Published: 21 August 2017
Cited by 6 | Viewed by 2104 | PDF Full-text (1276 KB) | HTML Full-text | XML Full-text
Abstract
Demand estimation in a water distribution network provides crucial data for monitoring and controlling systems. Because of budgetary and physical constraints, there is a need to estimate water demand from a limited number of sensor measurements. The demand estimation problem is underdetermined because [...] Read more.
Demand estimation in a water distribution network provides crucial data for monitoring and controlling systems. Because of budgetary and physical constraints, there is a need to estimate water demand from a limited number of sensor measurements. The demand estimation problem is underdetermined because of the limited sensor data and the implicit relationships between nodal demands and pressure heads. A simulation optimization technique using the water distribution network hydraulic model and an evolutionary algorithm is a potential solution to the demand estimation problem. This paper presents a detailed process simulation model for water demand estimation using the particle swarm optimization (PSO) algorithm. Nodal water demands and pipe flows are estimated when the number of estimated parameters is more than the number of measured values. The water demand at each node is determined by using the PSO algorithm to identify a corresponding demand multiplier. The demand multipliers are encoded with varying step sizes and the optimization algorithm particles are also discretized in order to improve the computation time. The sensitivity of the estimated water demand to uncertainty in demand multiplier discrete values and uncertainty in measured parameters is investigated. The sensor placement locations are selected using an analysis of the sensitivity of measured nodal heads and pipe flows to the change in the water demand. The results show that nodal demands and pipe flows can be accurately determined from a limited number of sensors. Full article
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Open AccessArticle
Simulation and Regulation of Market Operation in Hydro-Dominated Environment: The Yunnan Case
Water 2017, 9(8), 623; https://doi.org/10.3390/w9080623
Received: 13 July 2017 / Revised: 4 August 2017 / Accepted: 16 August 2017 / Published: 20 August 2017
Cited by 4 | Viewed by 1402 | PDF Full-text (2037 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an integrated method to obtain optimal market operation and regulation with the objective of reducing the market price and increasing the electricity consumption in hydro-dominated electricity markets, in which giant cascaded hydropower facilities along different rivers are main power suppliers. [...] Read more.
This paper presents an integrated method to obtain optimal market operation and regulation with the objective of reducing the market price and increasing the electricity consumption in hydro-dominated electricity markets, in which giant cascaded hydropower facilities along different rivers are main power suppliers. To this end, a comprehensive indicator composed of market prices and electricity consumption is proposed to evaluate the situation of hydro-dominated market operation. Moreover, an iterative algorithm is proposed to investigate the strategic behaviors of power suppliers and to simulate the operation of the market. Furthermore, an integrated solution methodology based on a multi-core parallel tabu genetic algorithm (MPTGA) is proposed to provide the optimal assignment of bilateral contracts, considering the market simulation, in order to achieve the optimal market regulation. The results from the case study, with real data based on Yunnan’s electricity market, demonstrate that the proposed indicator and method are effective and efficient to simulate and regulate the market operation, and the effects of MPTGA are discussed last. Full article
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Open AccessArticle
Relating Water Use to Tree Vitality of Populus euphratica Oliv. in the Lower Tarim River, NW China
Water 2017, 9(8), 622; https://doi.org/10.3390/w9080622
Received: 4 June 2017 / Revised: 4 August 2017 / Accepted: 17 August 2017 / Published: 19 August 2017
Cited by 7 | Viewed by 1477 | PDF Full-text (3957 KB) | HTML Full-text | XML Full-text
Abstract
This study aimed to compare the hydraulic characteristics of different vitalities of Populus euphratica to reveal the differences in their water use strategies and water consumption to provide useful data to scale water use of riparian poplar forests in the lower reaches of [...] Read more.
This study aimed to compare the hydraulic characteristics of different vitalities of Populus euphratica to reveal the differences in their water use strategies and water consumption to provide useful data to scale water use of riparian poplar forests in the lower reaches of the Tarim River, Northwestern China. Our results showed that the sapwood area of P. euphratica could be estimated based on its correlation with tree biometric parameters. The sapwood area of vital poplars tended to be larger than the senesced poplar despite both having the same diameter at breast height. This indicates that poplar vitality should be taken into account when estimating its sapwood area. Therefore, we established two different sapwood area estimation models for vital and senesced poplar (sapwood area = 1.452 × DBH1.553, R2 = 0.891; sapwood area = 0.915 × DBH1.618, R2 = 0.718; DBH: diameter at breast height). The sap flow process of vital and senesced poplar had certain differences and similarities; the average diurnal sap flow velocity and water consumption of vital poplar were 15.85 cm/h and 45.95 L, respectively; for the senesced poplar, it was 9.64 cm/h and 18.17 L, respectively, which were smaller than that of vital poplars. The influence of environmental factors on the sap flow velocity of two different P. euphratica was similar; the sap flow of both vital and senesced poplar had positive correlation with air temperature (R2 = 0.800 and 0.851), solar radiation (R2 = 0.732 and 0.778), vapor pressure deficit (R2 = 0.508 and 0.643) and groundwater depth (R2 = 0.301 and 0.171), while negative correlation with air humidity (R2 = −0.313 and −0.478). Full article
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Open AccessFeature PaperArticle
River Water Quality: Who Cares, How Much and Why?
Water 2017, 9(8), 621; https://doi.org/10.3390/w9080621
Received: 2 August 2017 / Revised: 15 August 2017 / Accepted: 17 August 2017 / Published: 19 August 2017
Cited by 4 | Viewed by 2487 | PDF Full-text (1429 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
An important motivation for the implementation of the Water Framework Directive is the creation of non-market environmental benefits, such as improved ecological quality, or greater opportunities for open-access river recreation via microbial pollution remediation. Pollution sources impacting on ecological or recreational water quality [...] Read more.
An important motivation for the implementation of the Water Framework Directive is the creation of non-market environmental benefits, such as improved ecological quality, or greater opportunities for open-access river recreation via microbial pollution remediation. Pollution sources impacting on ecological or recreational water quality may be uncorrelated, but non-market benefits arising from riverine improvements are typically conflated within benefit valuation studies. Using stated preference choice experiments embedded within a survey that also collected respondents’ socio-economic characteristics, we aimed to disaggregate these sources of value for different river users, thereby allowing decision makers to understand the consequences of adopting alternative investment strategies. Our results suggested that anglers derived greater value from improvements to the ecological quality of river water, in contrast to swimmers and rowers, for whom greater value is gained from improvements to recreational quality. More generally, we found three distinct groups of respondents: a majority preferring ecological over recreational improvements, a substantial minority holding opposing preference orderings, and a yet smaller proportion expressing relatively low values for either form of river quality enhancement. As such, this research demonstrates that the non-market benefits that may accrue from different types of water quality improvements are nuanced in terms of their potential beneficiaries and, by inference, their overall value and policy implications. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle
The Impact of Cropland Balance Policy on Ecosystem Service of Water Purification—A Case Study of Wuhan, China
Water 2017, 9(8), 620; https://doi.org/10.3390/w9080620
Received: 29 June 2017 / Revised: 16 August 2017 / Accepted: 16 August 2017 / Published: 18 August 2017
Cited by 2 | Viewed by 1634 | PDF Full-text (3174 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Urbanization has been responsible for the loss of cropland worldwide, especially in China. Since this trend is expected to continue in the near future, China has implemented the strictest cropland protection policies in the world, to guarantee its national food security. However, the [...] Read more.
Urbanization has been responsible for the loss of cropland worldwide, especially in China. Since this trend is expected to continue in the near future, China has implemented the strictest cropland protection policies in the world, to guarantee its national food security. However, the negative impact of cropland protection policies on ecosystem services has always been ignored. In this paper, we used LANDSCAPE (Land System Cellular Automata model for Potential Effects) model to assess the ecological lands loss under different scenarios in Wuhan, China during S2010–2020. Our scenarios differ in whether or not the cropland protection policy is imposed. Then, the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model was used to calculate the amount of nutrient export under two different scenarios and to analyze the mechanism of impact of Cropland Balance Policy on water purification. Results show that the scenarios with strict cropland protection (CP) will lead to more losses of ecological lands compared with scenarios without cropland protection (NCP). Besides, the nitrogen export in the CP scenario is average 8.6% higher than the NCP scenario, which indicates that the Cropland Balance Policy has a negative impact on water purification. The nitrogen export is transported mainly by subsurface, which is 1.73 times higher than the surface averaged over the two scenarios. Accordingly, this study proposed that reasonable land use planning, and lowering the nutrient delivery ratio would be more beneficial to the ecosystem service of water purification. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle
Measuring Recovery to Build up Metrics of Flood Resilience Based on Pollutant Discharge Data: A Case Study in East China
Water 2017, 9(8), 619; https://doi.org/10.3390/w9080619
Received: 14 June 2017 / Revised: 31 July 2017 / Accepted: 15 August 2017 / Published: 18 August 2017
Cited by 1 | Viewed by 1581 | PDF Full-text (6236 KB) | HTML Full-text | XML Full-text
Abstract
Building “disaster-resilient” rather than “disaster-resistant” cities/communities requires the development of response capabilities to natural disasters and subsequent recovery. This study devises a new method to measure resilience via recovery capability to validate indicators from social, economic, infrastructural, and environmental domains. The pollutant discharge [...] Read more.
Building “disaster-resilient” rather than “disaster-resistant” cities/communities requires the development of response capabilities to natural disasters and subsequent recovery. This study devises a new method to measure resilience via recovery capability to validate indicators from social, economic, infrastructural, and environmental domains. The pollutant discharge data (waste-water and waste-gas discharge/emission data) of local power plants, sewage treatment plants and main factories were used to monitor recovery process of both people’s living and local industrial production as the waste water/gas is released irregularly during the short disaster-hit period. A time series analysis of such data was employed to detect the disturbance on these infrastructures from disasters and to assess community recovery capability. A recent record-breaking flash flood in Changzhou, a city in eastern-central China, was selected as a case study. We used ordinal logistic regression to identify leading proxies of flood resilience. A combination of six variables related to socioeconomic factors, infrastructure development and the environment, stood out and explained 61.4% of the variance in measured recovery capability. These findings substantiate the possibility of using recovery measurement based on pollutant discharge to validate resilience metrics, and contribute more solid evidences for policy-makers and urban planners to make corresponding measures for resilience enhancement. Full article
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Open AccessArticle
Defining Runoff Indices and Analyzing Their Relationships with Associated Precipitation and Temperature Indices for Upper River Basins in the Northwest Arid Region of China
Water 2017, 9(8), 618; https://doi.org/10.3390/w9080618
Received: 9 May 2017 / Revised: 14 August 2017 / Accepted: 14 August 2017 / Published: 18 August 2017
Cited by 3 | Viewed by 1034 | PDF Full-text (7345 KB) | HTML Full-text | XML Full-text
Abstract
The northwest arid region (NAR) of China, located in a cold region, has been experiencing extreme weather and runoff events for years. Summer (from June to August) is the main season for forming runoff in this region. Summer runoff is contributed by glacial [...] Read more.
The northwest arid region (NAR) of China, located in a cold region, has been experiencing extreme weather and runoff events for years. Summer (from June to August) is the main season for forming runoff in this region. Summer runoff is contributed by glacial runoff in addition to precipitation in glacierized basins. The upper basins of Hei River, Shule River, Kaidu River, and Manas River with different glacier coverage and available daily average discharge data were selected in this study. Two runoff indices—maximum discharge difference (MDD) and accumulated direct discharge (ADD)—were defined and calculated for each runoff event in the time series of daily average discharge during 1961–2007. To provide scientific knowledge for managing water resources and preventing disasters, the relationships between summer runoff indices and their associated precipitation and temperature variables were obtained by linear regression analysis. Results suggest that the regulation of glacier on runoff is more significant with the increase of glacier coverage. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle
Different Irrigation Water Requirements of Seed Corn and Field Corn in the Heihe River Basin
Water 2017, 9(8), 606; https://doi.org/10.3390/w9080606
Received: 24 June 2017 / Revised: 4 August 2017 / Accepted: 9 August 2017 / Published: 18 August 2017
Cited by 7 | Viewed by 1339 | PDF Full-text (1401 KB) | HTML Full-text | XML Full-text
Abstract
The Heihe River is the second largest river in arid areas of China, and the irrigation water of oasis agriculture in its middle reaches accounts for almost 80% of the water resources in the whole watershed. Corn is the most important crop in [...] Read more.
The Heihe River is the second largest river in arid areas of China, and the irrigation water of oasis agriculture in its middle reaches accounts for almost 80% of the water resources in the whole watershed. Corn is the most important crop in the middle reaches of the Heihe River, and its water consumption is about 50% of the total agriculture water consumption of the middle reaches. Therefore, in order to effectively use the water resources in the watershed, it is crucial to improve the efficiency of corn irrigation. In this paper, using the Ganzhou District in the middle reaches of the Heihe River as the study region, we carried out a field survey to obtain characteristics of seed and field corn. Based on our results, we conducted parameter calibration using the CROPWAT model and calculated the irrigation water requirements (IWR) of these two corn types. The irrigation water requirements of seed and field corn in the growing seasons were 470.1 and 488.5 mm, respectively. However, we observed big differences in the water consumption sequences of these two corn types. Prior to mid-July, evapotranspiration and IWR of seed corn were 14.3% and 20.1% higher, respectively, than those of field corn. In September, IWR of the two corn types started to decrease, with a value of 82.3 mm for seed corn, which was 32.1% lower than the IWR of field corn (108.7 mm) during the same period. However, there were no significant differences in the irrigation time and single irrigation amount for seed and field corn in the study area. Since corn is widely cultivated in the Zhangye Region, there is a considerable water-saving potential in agriculture if the irrigation water consumption can be adjusted according to the IWR of the two corn types. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle
Recent Sedimentation Rates of Shallow Lakes in the Middle and Lower Reaches of the Yangtze River: Patterns, Controlling Factors and Implications for Lake Management
Water 2017, 9(8), 617; https://doi.org/10.3390/w9080617
Received: 7 June 2017 / Revised: 10 August 2017 / Accepted: 10 August 2017 / Published: 17 August 2017
Cited by 3 | Viewed by 1960 | PDF Full-text (5290 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Significantly increased sedimentation rates (SRs) in lakes worldwide in recent decades due to higher inputs of silt and eutrophication have led to significant environmental problems such as lake size diminishment and degraded water quality. Many lakes in the middle and lower reaches of [...] Read more.
Significantly increased sedimentation rates (SRs) in lakes worldwide in recent decades due to higher inputs of silt and eutrophication have led to significant environmental problems such as lake size diminishment and degraded water quality. Many lakes in the middle and lower reaches of the Yangtze River basin (MLYB) have followed this pattern. For effective lake management, it is essential to understand the pattern and drivers of SRs in these lakes. Fourteen typical lakes in the MLYB were chosen to examine the spatiotemporal patterns of SRs and identify the drivers over different time periods. Since 1900, SRs increased from <0.2 to 0.3–0.6 g·cm−2·year−1, particularly notable during 1930–1990. Combined with climatic factors, SR correlated negatively with lake (catchment) size and abundance of aquatic vegetation, whereas other lake features including nutrient status did not contribute significantly to the variation in SRs, due to the fast decomposition processes of organic matter in shallow lakes. Detrimental land use practices especially reclamation for croplands and rapid urbanization was revealed to elevate SRs pronouncedly. We propose various management strategies aiming to maintain SR reference condition at ~0.16 ± 0.08 g·cm−2·year−1, which is analogous to the SR value between 1850 and 1900. Full article
(This article belongs to the Special Issue Ecological Responses of Lakes to Climate Change)
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Open AccessArticle
Spatiotemporal Patterns of Crop Irrigation Water Requirements in the Heihe River Basin, China
Water 2017, 9(8), 616; https://doi.org/10.3390/w9080616
Received: 30 June 2017 / Revised: 14 August 2017 / Accepted: 15 August 2017 / Published: 17 August 2017
Cited by 8 | Viewed by 1930 | PDF Full-text (21371 KB) | HTML Full-text | XML Full-text
Abstract
Agricultural expansion, population growth, rapid urbanization, and climate change have all significantly impacted global water supply and demand and have led to a number of negative consequences including ecological degradation and decreases in biodiversity, especially in arid and semi-arid areas. The agricultural sector [...] Read more.
Agricultural expansion, population growth, rapid urbanization, and climate change have all significantly impacted global water supply and demand and have led to a number of negative consequences including ecological degradation and decreases in biodiversity, especially in arid and semi-arid areas. The agricultural sector consumes the most water globally; crop irrigation alone uses up more than 80% of available agricultural water. Thus, to maintain sustainable development of the global economy and ecosystems, it is crucial to effectively manage crop irrigation water. We focus on the arid and semi-arid Heihe River Basin (HRB), China, as a case study in this paper, extracting spatiotemporal information on the distribution of crop planting using multi-temporal Thematic Mapper and Enhanced Thematic Mapper Plus (TM/ETM+) remote sensing (RS) images. We estimate the spatiotemporal crop irrigation water requirements (IWRc) using the Food and Agriculture Organization of the United Nations (FAO) Penman-Monteith method and reveal variations in IWRc. We also analyze the impact of changes in crop planting structure on IWRc and discuss strategies for the rational allocation of irrigation water as well as policies to alleviate imbalance between water supply and demand. The results of this study show that effective rainfall (ER) decreases upstream-to-downstream within the HRB, while crop evapotranspiration under standard conditions (ETc) increases, leading to increasing spatial variation in IWRc from zero up to 150 mm and between 300 and 450 mm. Data show that between 2007 and 2012, annual mean ER decreased from 139.49 to 106.29 mm, while annual mean ETc increased from 483.87 to 500.38 mm, and annual mean IWRc increased from 339.95 to 370.11 mm. Data show that monthly mean IWRc initially increased before decreasing in concert with crop growth. The largest values for this index were recorded during the month of June; results show that IWRc for May and June decreased by 8.14 and 11.67 mm, respectively, while values for July increased by 5.75 mm between 2007 and 2012. These variations have helped to ease the temporal imbalance between water supply and demand. Mean IWRc values for oilseed rape, corn, barley, and other crops all increased over the study period, from 208.43, 349.35, 229.26, and 352.85 mm, respectively, in 2007, to 241.81, 393.10, 251.17, and 378.86 mm, respectively, in 2012. At the same time, the mean IWRc of wheat decreased from 281.53 mm in 2007 to 266.69 mm in 2012. Mainly because of changes in planting structure, the total IWRc for the HRB in 2012 reached 2692.58 × 106 m3, an increase of 332.16 × 106 m3 (14.07%) compared to 2007. Data show that 23.11% (76.77 × 106 m3) of this increase is due to crop transfers, while the remaining 76.89% (255.39 × 106 m3) is the result of the rapid expansion of cultivated land. Thus, to maintain both the sustainable development and ecological security of the HRB, it is crucial to efficiently manage and utilize agricultural water in light of spatiotemporal patterns in IWRc changes as well as IWRc variations between different crops. The cultivation of water-demanding crops and the further expansion of agricultural land should also be avoided. Full article
(This article belongs to the Special Issue Sustainable Water Management within Inland River Watershed)
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Open AccessArticle
Wet Spells and Associated Moisture Sources Anomalies across Danube River Basin
Water 2017, 9(8), 615; https://doi.org/10.3390/w9080615
Received: 29 May 2017 / Revised: 10 August 2017 / Accepted: 15 August 2017 / Published: 17 August 2017
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Abstract
The Danube River Basin is the second longest catchment basin in Europe and exhibits intense climatological diversity. In recent decades, the frequency and intensity of daily precipitation extremes have suffered from an increment in many parts of the world, including Central and Eastern [...] Read more.
The Danube River Basin is the second longest catchment basin in Europe and exhibits intense climatological diversity. In recent decades, the frequency and intensity of daily precipitation extremes have suffered from an increment in many parts of the world, including Central and Eastern Europe. Wet spells are defined by the number of consecutive rainy days with different thresholds. The identification of wet spells and their trends in the rainfall time is very important for many sectors, such as agriculture, ecology, hydrology and water resources. Wet spells can lead to extreme events and cause floods and other disasters. In this study, we will attempt to characterise global precipitation in the context of wet spells and associated precipitation depth of wet spells in the Danube River Basin area using daily precipitation data, as well as analysing different approaches to identifying wet spells. The ten most intense wet spells were detected, and the most intense, which occurred on 23 September 1996, was studied in depth in terms of precipitation and associated anomalies, the synoptic situation and the anomalous transport of moisture using a Lagrangian approach. The existence of a marked west-east dipole in the field of sea level pressure between the Atlantic Ocean and the eastern Mediterranean leads to the anomalous moisture transport from the Northern Atlantic Ocean to the Mediterranean Sea, where a higher available amount of moisture existed, and subsequently penetrated within the low positioned over the Danube River Basin. In addition, an Atmospheric River was also responsible for the wet conditions in the Danube River Basin. The combination of all these factors was responsible for the extreme precipitation linked with the wet spell. Full article
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Open AccessArticle
Distributed Hydrological Modeling: Determination of Theoretical Hydraulic Potential & Streamflow Simulation of Extreme Hydrometeorological Events
Water 2017, 9(8), 602; https://doi.org/10.3390/w9080602
Received: 12 June 2017 / Revised: 28 July 2017 / Accepted: 9 August 2017 / Published: 17 August 2017
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Abstract
The progressive change in climatic conditions worldwide has increased frequency and severity of extreme hydrometeorological events (EHEs). México is an example that has been affected by the occurrence of EHE leading to economic, social, and environmental losses. The objective of this research was [...] Read more.
The progressive change in climatic conditions worldwide has increased frequency and severity of extreme hydrometeorological events (EHEs). México is an example that has been affected by the occurrence of EHE leading to economic, social, and environmental losses. The objective of this research was to apply a Canadian distributed hydrological model (DHM) to tropical conditions and to evaluate its capacity to simulate flows in a basin in the central Gulf of Mexico. In addition, the DHM (once calibrated and validated) was used to calculate the theoretical hydraulic power (THP) and the performance to predict streamflow before the presence of an EHE. The results of the DHM show that the goodness of fit indicators between the observed and simulated flows in the calibration process Nash-Sutcliffe efficiency (NSE) = 0.83, ratio of the root mean square error to the standard deviation of measured data (RSR) = 0.41, and percent bias (PBIAS) = −4.3) and validation (NSE = 0.775, RSR = 0.4735, and PBIAS = 2.45) are satisfactory. The DHM showed its applicability: determination of THP showed that the mean flows are in synchrony with the order of the river reaches and streamflow simulation of 13 EHEs (NSE = 0.78 ± 0.13, RSR = 0.46 ± 0.14 and PBIAS = −0.48 ± 7.5) confirmed a reliable efficiency. This work can serve as a tool for identifying vulnerabilities before floods and for the rational and sustainable management of water resources. Full article
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Open AccessArticle
Exploring Jeddah Floods by Tropical Rainfall Measuring Mission Analysis
Water 2017, 9(8), 612; https://doi.org/10.3390/w9080612
Received: 13 June 2017 / Revised: 31 July 2017 / Accepted: 10 August 2017 / Published: 16 August 2017
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Abstract
Estimating flash floods in arid regions is a challenge arising from the limited time preventing mitigation measures from being taken, which results in fatalities and property losses. Here, Tropical Rainfall Measuring Mission (TRMM) Multi Satellite Precipitation Analysis (TMPA) Real Time (RT) 3B2RT data [...] Read more.
Estimating flash floods in arid regions is a challenge arising from the limited time preventing mitigation measures from being taken, which results in fatalities and property losses. Here, Tropical Rainfall Measuring Mission (TRMM) Multi Satellite Precipitation Analysis (TMPA) Real Time (RT) 3B2RT data are utilized in estimating floods that occurred over the city of Jeddah located in the western Kingdom of Saudi Arabia. During the 2000–2014 period, six floods that were effective on 19 days occurred in Jeddah. Three indices, constant threshold (CT), cumulative distribution functions (CDFs) and Jeddah flood index (JFI), were developed using 15-year 3-hourly 3B42RT. The CT calculated, as 10.37 mm/h, predicted flooding on 14 days, 6 of which coincided with actual flood-affected days (FADs). CDF thresholds varied between 87 and 93.74%, and JFI estimated 28 and 20 FADs where 8 and 7 matched with actual FADs, respectively. While CDF and JFI did not miss any flood event, CT missed the floods that occurred in the heavy rain months of January and December. The results are promising despite that only rainfall rates, i.e., one parameter out of various flood triggering mechanisms, i.e., soil moisture, topography and land use, are used. The simplicity of the method favors its use in TRMM follow-on missions such as the Global Precipitation Measurement Mission (GPM). Full article
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Open AccessArticle
Aspects of Hexavalent Chromium Pollution of Thebes Plain Aquifer, Boeotia, Greece
Water 2017, 9(8), 611; https://doi.org/10.3390/w9080611
Received: 12 June 2017 / Revised: 4 August 2017 / Accepted: 8 August 2017 / Published: 16 August 2017
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Abstract
The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of [...] Read more.
The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of 20 samples from the study area was conducted as well as an isotopic analysis of Cr and Sr isotopes. Hexavalent chromium pollution can be triggered by human pollutant activity or specific geological environments. Stable Cr isotopic analysis gave δ53Cr positive values in several samples which supports the second hypothesis, but the limitations of that theory do not allow safe conclusions in all cases. Nitrates and Sr ratios suggest fertilizer contamination and the presence of SiO2-leaching of silicate rocks. Full article
(This article belongs to the Special Issue Heavy Metals and Potentially Toxic Elements (PTEs) in Water)
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Open AccessArticle
Assessment of Nitrogen Inputs into Hunt River by Onsite Wastewater Treatment Systems via SWAT Simulation
Water 2017, 9(8), 610; https://doi.org/10.3390/w9080610
Received: 15 June 2017 / Revised: 20 July 2017 / Accepted: 8 August 2017 / Published: 16 August 2017
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Abstract
Nonpoint source nitrogen pollution is difficult to effectively model in groundwater systems. This study aims to elucidate anthropogenic nonpoint source pollution discharging into Potowomut Pond and ultimately Narragansett Bay. Hydrologic modeling with Soil and Water Assessment Tool (SWAT) and SWAT Calibration and Uncertainty [...] Read more.
Nonpoint source nitrogen pollution is difficult to effectively model in groundwater systems. This study aims to elucidate anthropogenic nonpoint source pollution discharging into Potowomut Pond and ultimately Narragansett Bay. Hydrologic modeling with Soil and Water Assessment Tool (SWAT) and SWAT Calibration and Uncertainty Program (SWAT-CUP) was used to simulate streamflow and nitrogen levels in the Hunt River with and without onsite wastewater treatment systems (OWTS). The objective of this study was to determine how input of OWTS data impacts nitrogen loading into the Hunt River Watershed in Rhode Island, USA. The model was simulated from 2006 to 2014, calibrated from 2007 to 2011 and validated from 2012 to 2014. Observed streamflow data was sourced from a US Geological Survey gauge and nitrogen loading data from University of Rhode Island Watershed Watch (URIWW). From the results, adding OWTS data to the SWAT simulation produced a better calibration and validation fit for total fit (Nash–Sutcliffe Efficiency (NSE) = 0.50 calibration, 0.78 validation) when compared with SWAT simulation without OWTS data (NSE = −1.3 calibration, −6.95) validation. Full article
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Open AccessArticle
Improved Medium- and Long-Term Runoff Forecasting Using a Multimodel Approach in the Yellow River Headwaters Region Based on Large-Scale and Local-Scale Climate Information
Water 2017, 9(8), 608; https://doi.org/10.3390/w9080608
Received: 21 June 2017 / Revised: 2 August 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
Cited by 3 | Viewed by 1256 | PDF Full-text (3255 KB) | HTML Full-text | XML Full-text
Abstract
Medium- and long-term runoff forecasting is essential for hydropower generation and water resources coordinated regulation in the Yellow River headwaters region. Climate change has a great impact on runoff within basins, and incorporating different climate information into runoff forecasting can assist in creating [...] Read more.
Medium- and long-term runoff forecasting is essential for hydropower generation and water resources coordinated regulation in the Yellow River headwaters region. Climate change has a great impact on runoff within basins, and incorporating different climate information into runoff forecasting can assist in creating longer lead-times in planning periods. In this paper, a multimodel approach was developed to further improve the accuracy and reliability of runoff forecasting fully considering of large-scale and local-scale climatic factors. First, with four large-scale atmospheric oscillations, sea surface temperature, precipitation, and temperature as the predictors, multiple linear regression (MLR), radial basis function neural network (RBFNN), and support vector regression (SVR) models were built. Next, a Bayesian model averaging (BMA)-based multimodel was developed using weighted MLR, RBFNN, and SVR models, and the performance of the BMA-based multimodel was compared to those of the MLR, RBFNN, and SVR models. Finally, the high-runoff performance of these four models was further analyzed to prove the effectiveness of each model. The BMA-based multimodel performed better than those of the other models, as well as high-runoff forecasting. The results also revealed that the performance of the forecasting models with multiple climatic factors were generally superior to that without climatic factors. The BMA-based multimodel with climatic factors not only provides a promising, reliable method for medium- and long-term runoff forecasting, but also facilitates uncertainty estimation under different confidence intervals. Full article
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Open AccessArticle
Agreement of Four Equations for Computing Dewfall in Northern Germany
Water 2017, 9(8), 607; https://doi.org/10.3390/w9080607
Received: 3 June 2017 / Revised: 2 August 2017 / Accepted: 8 August 2017 / Published: 15 August 2017
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Abstract
The energy balance (EB), turbulent vapour transport (TVT), Penman-Monteith (PM) and Bowen ratio energy balance (BREB) equation were used to estimate dewfall based on meteorological data. Initially there were big disagreements between the estimates from these four equations. However, after multiplying the heat [...] Read more.
The energy balance (EB), turbulent vapour transport (TVT), Penman-Monteith (PM) and Bowen ratio energy balance (BREB) equation were used to estimate dewfall based on meteorological data. Initially there were big disagreements between the estimates from these four equations. However, after multiplying the heat and vapour conductance terms by 0.33 the agreement was much better. This implies that the disagreements derived from improper conductance values. Initially we did not consider the effect of atmospheric stability on the conductances. With stability correction the conductances were on average 0.5 times the values without stability correction. To arrive at the aforementioned 0.33, the conductances with stability correction still need to be lower by a factor of 0.66. The value of the von Karman constant and the relationships for the zero plane displacement and the roughness length we used in our conductance computations are widely used, but not the only possible ones. With different values and relationships also suggested in the literature one can reach this factor. However, it is also possible that our wind speed data contributed to the fact that the conductances we computed were too high. Their computation for a given canopy—atmosphere system requires wind speeds from a wind profile in equilibrium with the vegetation. This in turn requires an adequate fetch around the investigated surface. The highly varied vegetation in and around the site where the study was conducted makes adequate fetch rather doubtful. To obtain valid conductance values the atmospheric stability conditions must be considered, the appropriate values for the von Karman constant, the zero plane displacement and roughness length must be used, and there must be adequate fetch. The BREB equation does not contain a conductance term and therefore does not suffer from the problems just stated. The other three equations do. However, the BREB, like the EB and TVT equations, need the surface temperature which is not routinely measured. This then leaves the PM equation from which this temperature has been eliminated as the only option. Hence, in a future study dewfall estimates from the PM equation should be compared with direct measurements with a high precision weighing lysimeter. Full article
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Open AccessFeature PaperArticle
Watershed Variability in Streambank Erodibility and Implications for Erosion Prediction
Water 2017, 9(8), 605; https://doi.org/10.3390/w9080605
Received: 15 June 2017 / Revised: 8 August 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
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Abstract
Two fluvial erosion models are commonly used to simulate the erosion rate of cohesive soils: the empirical excess shear stress model and the mechanistic Wilson model. Both models include two soil parameters, the critical shear stress (τc) and the erodibility [...] Read more.
Two fluvial erosion models are commonly used to simulate the erosion rate of cohesive soils: the empirical excess shear stress model and the mechanistic Wilson model. Both models include two soil parameters, the critical shear stress (τc) and the erodibility coefficient (kd) for the excess shear stress model and b0 and b1 for the Wilson model. Jet erosion tests (JETs) allow for in-situ determination of these parameters. JETs were completed at numerous sites along two streams in each the Illinois River and Fort Cobb Reservoir watersheds. The objectives were to use JET results from these streambank tests to investigate variability of erodibility parameters on the watershed scale and investigate longitudinal trends in streambank erodibility. The research also determined the impact of this variability on lateral retreat predicted by a process-based model using both the excess shear stress model and the Wilson model. Parameters derived from JETs were incorporated into a one-dimensional process-based model to simulate bank retreat for one stream in each watershed. Erodibility parameters varied by two to five and one to two orders of magnitude in the Illinois River watershed and Fort Cobb Reservoir watershed, respectively. Less variation was observed in predicted retreat by a process-based model compared to the input erodibility parameters. Uncalibrated erodibility parameters and simplified applied shear stress estimates failed to match observed lateral retreats suggesting the need for model calibration and/or advanced flow modeling. Full article
(This article belongs to the Special Issue Streambank Erosion: Monitoring, Modeling and Management)
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Open AccessArticle
A Web Based Interface for Distributed Short-Term Soil Moisture Forecasts
Water 2017, 9(8), 604; https://doi.org/10.3390/w9080604
Received: 26 June 2017 / Revised: 31 July 2017 / Accepted: 11 August 2017 / Published: 15 August 2017
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Abstract
Agricultural non-point source (NPS) pollution is a source of water quality impairment, and demonstrates widely varying spatial and temporal pollution potential. Many efforts to protect water quality are based on seasonal and annual estimates of pollutant loss potential (NRCS 590 nutrient management standard, [...] Read more.
Agricultural non-point source (NPS) pollution is a source of water quality impairment, and demonstrates widely varying spatial and temporal pollution potential. Many efforts to protect water quality are based on seasonal and annual estimates of pollutant loss potential (NRCS 590 nutrient management standard, P-Index) that inadequately address the hydrologic processes driving NPS pollution. One barrier to adopting practices that address NPS pollution is a lack of tools capable of transferring information at sufficient spatial and temporal resolution so that end-users can make informed decisions. We introduce a web-based system displaying distributed hydrologic forecasts using free and open source software. The system consists of three primary components: (1) a hydrology model that provides short-term distributed forecasts; (2) a data structure capable of re-structuring large, high resolution rasters; (3) an interface employing adaptive map-viewing technology that allows end-users to interact with the data to avoid high-risk areas when planning agricultural practices. Full article
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Open AccessArticle
Understanding the Temperature Variations and Thermal Structure of a Subtropical Deep River-Run Reservoir before and after Impoundment
Water 2017, 9(8), 603; https://doi.org/10.3390/w9080603
Received: 27 June 2017 / Revised: 2 August 2017 / Accepted: 10 August 2017 / Published: 15 August 2017
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Abstract
A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013–2014) using measured data as model input. It was calibrated using observed temperature [...] Read more.
A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013–2014) using measured data as model input. It was calibrated using observed temperature profiles near the dam and the outflow temperatures. Observed daily temperatures at four gauging stations upstream or downstream of XLDR before (2000–2012) and after the impoundment (4 May 2013) were analyzed and fitted with a sine function representing seasonal temperature variation. The fitted annual temperature phase shifts showed no phase delay in XLDR area before the impoundment but revealed a phase delay about 17 days between outflow and inflow after the impoundment, which was not caused by the air temperature variation. The simulated temperatures verified a similar phase delay after the impoundment. The simulated temperatures, water ages, and vertical temperature gradients demonstrated an average metalimnetic deepening rate of 0.49 m/day (average inflow ~4500 m3/s) while the largest rate due to massive inflow (~15,000 m3/s) was 1.67 m/day. The W2 model was run under hypothetic scenarios of different inflow/outflow rates and outflow withdrawn elevations. The results revealed that greater inflow/outflow rate could lead to higher metalimnetic deepening rate and smaller outflow phase delay, while deeper outflow withdrawn could lead to deeper metalimnion and larger epilimnetic depth. Full article
(This article belongs to the Special Issue Water Quality Monitoring and Modeling in Lakes)
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Open AccessArticle
Establishment of an Inventory for the Life Cycle Cost (LCC) Analysis of a Water Supply System
Water 2017, 9(8), 592; https://doi.org/10.3390/w9080592
Received: 7 March 2017 / Revised: 31 July 2017 / Accepted: 1 August 2017 / Published: 15 August 2017
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Abstract
This paper aimed to develop an inventory that is necessary for the life cycle cost (LCC) analysis of a water supply system. Based on an established inventory system, data items for each asset category were defined. The water supply system was divided into [...] Read more.
This paper aimed to develop an inventory that is necessary for the life cycle cost (LCC) analysis of a water supply system. Based on an established inventory system, data items for each asset category were defined. The water supply system was divided into pipelines, pumps and distribution facilities. Pipeline facilities that account for the majority of water supply systems were grouped, according to the purposes and functions of pipes, into conveyance facilities, transmission facilities, distribution facilities and supply facilities. The inventory of water supply systems were divided into five levels, and the higher the level, the more detailed facilities were classified. Basically, 12 items and diagnosis results were included in the system to distinguish the characteristics of each asset, and it was ensured that administrators could add or change items later if necessary. The data used in this study were established based on real data from the Yeong-Wol (YW) pipeline systems. Full article
(This article belongs to the Special Issue Water Networks Management: New Perspectives)
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Open AccessArticle
Sediment-Water Methane Flux in a Eutrophic Pond and Primary Influential Factors at Different Time Scales
Water 2017, 9(8), 601; https://doi.org/10.3390/w9080601
Received: 11 June 2017 / Revised: 21 July 2017 / Accepted: 10 August 2017 / Published: 14 August 2017
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Abstract
Water bodies are major areas for methane release. Eutrophic water bodies may promote methane flux. The sediment-water interface is the major location for methane release, and studies on sediment-water interactions are necessary to regulate methane release in water. However, relevant studies on methane [...] Read more.
Water bodies are major areas for methane release. Eutrophic water bodies may promote methane flux. The sediment-water interface is the major location for methane release, and studies on sediment-water interactions are necessary to regulate methane release in water. However, relevant studies on methane flux at the sediment-water interface are limited due to methodological difficulties. Using an innovative gas trapping device, this study investigated the seasonal characteristics and diel variation in summer methane flux from eutrophic water bodies and analyzed the correlations between temperature, dissolved oxygen (DO), different forms of nitrogen and the methane flux at different time scales. The results showed that methane flux in the eutrophic pond was high and had distinct seasonal variations and diel variations: the average value was 2.81 ± 0.19 mmol m−2 h−1 in summer, which was significantly greater than that in spring (0.62 ± 0.14 mmol m−2 h−1), autumn (0.63 ± 0.10 mmol m−2 h−1) (p < 0.01) and winter (approached zero). The diel characteristics of methane flux in summer exhibited a unimodal pattern of increase at night and decrease during the day. The correlation analysis showed that the sediment-water methane flux rate of the water body was significantly positively correlated with the temperature and NH4+ concentration and significantly negatively correlated with DO, NO3 and NO2 concentration. Meanwhile, among different time scales, the correlations between NO3/NH4+ concentration and methane flux were the highest at the diel scale in summer (R2 = 0.68, 0.87 respectively) when the temperature and DO vibration was low and the relationship between temperature/DO and methane flux was poor (R2 = 0.45, 0.87 respectively). This study considered that higher NH4+-N and lower NO3-N/NO2-N content in eutrophic water could have an effect on the high methane flux in summer as well as the low dissolved oxygen content. Full article
(This article belongs to the Special Issue Eutrophication of Waterways: An Old Problem with Modern Consequences)
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Open AccessArticle
Spatial and Seasonal Surface Water Quality Assessment in a Tropical Urban Catchment: Burío River, Costa Rica
Water 2017, 9(8), 558; https://doi.org/10.3390/w9080558
Received: 9 June 2017 / Revised: 11 July 2017 / Accepted: 17 July 2017 / Published: 13 August 2017
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Abstract
Water quality assessments are essential for providing information regarding integrated water resource management processes. This study presents the results of a spatial and seasonal surface water quality assessment of the Burío river sub-catchment in Costa Rica. Fourteen sample campaigns were conducted at eight [...] Read more.
Water quality assessments are essential for providing information regarding integrated water resource management processes. This study presents the results of a spatial and seasonal surface water quality assessment of the Burío river sub-catchment in Costa Rica. Fourteen sample campaigns were conducted at eight sample sites between 2005 and 2010. Seasonal variations were evaluated using linear mixed-effects models where dissolved oxygen, total solids, and nitrate showed significant differences between dry and wet seasons (p < 0.05). Cluster analysis identified three clusters at the top, middle, and bottom of the catchment that were consistent with land use patterns, and principal component analysis identified the main parameters that were affecting 84% of the total variance in water quality (biochemical oxygen demand, dissolved oxygen, total phosphate, and nitrate). The National Sanitation Foundation Water Quality Index (NSF-WQI) results indicated the majority of the river consisted of mainly “medium” water quality, although “bad” and “good” water quality results were identified depending on sample site and season. This methodological approach provides a useful monitoring technique for local governments that can be used for further remediation strategies. Full article
(This article belongs to the Special Issue New Advances in Integrated River Basin Management)
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