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Water, Volume 7, Issue 10 (October 2015) – 34 articles , Pages 5203-5875

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4723 KiB  
Article
Water Discharge and Sediment Load Changes in China: Change Patterns, Causes, and Implications
by Chong Jiang, Linbo Zhang, Daiqing Li and Fen Li
Water 2015, 7(10), 5849-5875; https://doi.org/10.3390/w7105849 - 26 Oct 2015
Cited by 33 | Viewed by 7742
Abstract
In this research, monthly hydrological and daily meteorological data were collected across China for the period 1956–2012. Modified Mann–Kendall tests, double mass curve analysis, and correlation statistics were performed to identify the long-term trends and interrelation of the hydrometeorological variables and to examine [...] Read more.
In this research, monthly hydrological and daily meteorological data were collected across China for the period 1956–2012. Modified Mann–Kendall tests, double mass curve analysis, and correlation statistics were performed to identify the long-term trends and interrelation of the hydrometeorological variables and to examine the influencing factors of streamflow and sediment. The results are as follows: (1) In the last 60 years, the streamflow in northern China has shown different decreasing trends. For the southern rivers, the streamflow presented severe fluctuations, but the declining trend was insignificant. For the streamflow in western China, an increasing trend was shown. (2) In the northern rivers, the streamflow was jointly controlled by the East Asian monsoon and westerlies. In the southern rivers, the runoff was mainly influenced by the Tibet–Qinghai monsoon, the South Asian monsoon, and westerlies. (3) Sediment loads in the LCRB (Lancang River Basin) and YZRB (Yarlung Zangbo River Basin) did not present significant change trends, although other rivers showed different degrees of gradual reduction, particularly in the 2000s. (4) Underlying surface and precipitation changes jointly influenced the streamflow in eastern rivers. The water consumption for industrial and residential purposes, soil and water conservation engineering, hydraulic engineering, and underlying surface changes induced by other factors were the main causes of streamflow and sediment reduction. Full article
(This article belongs to the Special Issue Water Resource Variability and Climate Change)
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1894 KiB  
Article
Experiments and Numerical Simulations of Dike Erosion due to a Wave Impact
by Stefania Evangelista
Water 2015, 7(10), 5831-5848; https://doi.org/10.3390/w7105831 - 23 Oct 2015
Cited by 22 | Viewed by 6651
Abstract
Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex [...] Read more.
Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex task, and although numerical models are very powerful nowadays, real processes cannot be accurately predicted; therefore, physical models constitute a useful tool to investigate different features under controlled conditions. This paper presents some laboratory experimental results of erosion of a sand dike produced by the impact of a dam break wave. Experiments have been conducted in the Water Engineering Laboratory at the University of Cassino and Southern Lazio, Italy, in a rectangular channel: here, the sudden opening of a gate forming the reservoir generates the wave impacting the dike, made in turn of two different, almost uniform sands. The physical evidence proves that the erosion process is strongly unsteady and significantly different from a gradual overtopping and highlights the importance of apparent cohesion for the fine sand dike. The experimental results have also been compared against the ones obtained through the numerical integration of a two-phase model, which shows the reasonable predictive capability of the temporal free surface and dike profile evolution. Full article
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2146 KiB  
Article
Methods of the Water-Energy-Food Nexus
by Aiko Endo, Kimberly Burnett, Pedcris M. Orencio, Terukazu Kumazawa, Christopher A. Wada, Akira Ishii, Izumi Tsurita and Makoto Taniguchi
Water 2015, 7(10), 5806-5830; https://doi.org/10.3390/w7105806 - 23 Oct 2015
Cited by 164 | Viewed by 25667
Abstract
This paper focuses on a collection of methods that can be used to analyze the water-energy-food (WEF) nexus. We classify these methods as qualitative or quantitative for interdisciplinary and transdisciplinary research approaches. The methods for interdisciplinary research approaches can be used to unify [...] Read more.
This paper focuses on a collection of methods that can be used to analyze the water-energy-food (WEF) nexus. We classify these methods as qualitative or quantitative for interdisciplinary and transdisciplinary research approaches. The methods for interdisciplinary research approaches can be used to unify a collection of related variables, visualize the research problem, evaluate the issue, and simulate the system of interest. Qualitative methods are generally used to describe the nexus in the region of interest, and include primary research methods such as Questionnaire Surveys, as well as secondary research methods such as Ontology Engineering and Integrated Maps. Quantitative methods for examining the nexus include Physical Models, Benefit-Cost Analysis (BCA), Integrated Indices, and Optimization Management Models. The authors discuss each of these methods in the following sections, along with accompanying case studies from research sites in Japan and the Philippines. Although the case studies are specific to two regions, these methods could be applicable to other areas, with appropriate calibration. Full article
(This article belongs to the Special Issue Water-Energy-Food Nexus in Large Asian River Basins)
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3776 KiB  
Article
Spatio-Temporal Patterns of Water Table and Vegetation Status of a Deserted Area
by Limin Duan, Tingxi Liu, Xixi Wang and Yanyun Luo
Water 2015, 7(10), 5788-5805; https://doi.org/10.3390/w7105788 - 23 Oct 2015
Cited by 6 | Viewed by 5962
Abstract
Understanding groundwater-vegetation interactions is crucial for sustaining fragile environments of desert areas such as the Horqin Sandy Land (HSL) in northern China. This study examined spatio-temporal variations in the water table and the associated vegetation status of a 9.71 km2 area that [...] Read more.
Understanding groundwater-vegetation interactions is crucial for sustaining fragile environments of desert areas such as the Horqin Sandy Land (HSL) in northern China. This study examined spatio-temporal variations in the water table and the associated vegetation status of a 9.71 km2 area that contains meadowland, sandy dunes, and intermediate transitional zones. The depth of the water table and hydrometeorologic parameters were monitored and Landsat Thematic Mapper (TM) and Moderate Resolution Imaging Spectroradiometer (MODIS) data were utilized to assess the vegetation cover. Spatio-temporal variations over the six-year study period were examined and descriptive groundwater–vegetation associations developed by overlaying a water table depth map onto a vegetation index map derived from MODIS. The results indicate that the water table depends on the local topography, localized geological settings, and human activities such as reclamation, with fluctuations occurring at annual and monthly scales as a function of precipitation and potential evapotranspiration. Locations where the water table is closer to the surface tend to have more dense and productive vegetation. The water table depth is more closely associated with vegetative density in meadowlands than in transitional zones, and only poorly associated with vegetation in sandy dunes. Full article
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5666 KiB  
Article
Numerical Simulation of Groundwater Flow in a River Valley Basin in Jilin Urban Area, China
by Shuwei Qiu, Xiujuan Liang, Changlai Xiao, He Huang, Zhang Fang and Fengchao Lv
Water 2015, 7(10), 5768-5787; https://doi.org/10.3390/w7105768 - 21 Oct 2015
Cited by 26 | Viewed by 8113
Abstract
In order to evaluate the groundwater resources and aquifer system of the Jilin urban area (JUA), a groundwater numerical flow model was established by using the groundwater modeling system based on data from 190 boreholes. River stages were interpolated to control the groundwater [...] Read more.
In order to evaluate the groundwater resources and aquifer system of the Jilin urban area (JUA), a groundwater numerical flow model was established by using the groundwater modeling system based on data from 190 boreholes. River stages were interpolated to control the groundwater flow field. The input parameters such as hydraulic conductivity and specific yield were based on data from 260 pumping test data. The model was calibrated by trial and error, simulated results were compared to the observed head and contour maps, which were generally in good agreement, and the root mean squared error was 0.66 m. Sensitivity analysis was carried out and recharge proved to be the most sensitive factor in this model. The water budget showed that the input was 2.07× 108 m3/a, which was smaller than the output of 2.21 × 108 m3/a. A groundwater level decline and cone of depression exist in the Songhua and Aolong river valley. The JUA aquifer systems can be well and efficiently modeled by constructing a numerical model. Based on the supply and demand analysis of water resources, the established model would finally provide a scientific basis to use the groundwater resources sustainably in JUA. Full article
(This article belongs to the Special Issue Geospatial Modeling of River Systems)
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5481 KiB  
Article
Assessment of the Impact of New Investments on Flood Hazard-Study Case: The Bridge on the Warta River near Wronki
by Tomasz Dysarz, Joanna Wicher-Dysarz and Mariusz Sojka
Water 2015, 7(10), 5752-5767; https://doi.org/10.3390/w7105752 - 21 Oct 2015
Cited by 11 | Viewed by 5017
Abstract
The main concern of the study was the evaluation of the impact of new investment in road infrastructure on the flood hazard. The flood hazard is considered here on the basis of maps according to requirements of EU Flood Directive. The analyses presented [...] Read more.
The main concern of the study was the evaluation of the impact of new investment in road infrastructure on the flood hazard. The flood hazard is considered here on the basis of maps according to requirements of EU Flood Directive. The analyses presented were made for the Warta river, near the town of Wronki. The procedure included data collection and processing, model configuration, hydraulic simulation, generation of water surface profiles, and flood hazard maps. The ArcGIS tools, as well as HEC-RAS package, were used in this research. The model recalibration described in the paper provided excellent results according to independent criteria. Hence, the results obtained may be considered as valid. Finally the results reconstructing the conditions with and without the bridge are compared. The assessed impact of the bridge seems to be moderate, but the procedure proposed in the presented paper may be of wider application. In view of the EU Flood Directive and plans for investments in road infrastructure, the methodology presented seems very attractive. Full article
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2896 KiB  
Article
MODIS-Derived Spatiotemporal Changes of Major Lake Surface Areas in Arid Xinjiang, China, 2000–2014
by Qingting Li, Linlin Lu, Cuizhen Wang, Yingkui Li, Yue Sui and Huadong Guo
Water 2015, 7(10), 5731-5751; https://doi.org/10.3390/w7105731 - 21 Oct 2015
Cited by 26 | Viewed by 6367
Abstract
Inland water bodies, which are critical freshwater resources for arid and semi-arid areas, are very sensitive to climate change and human disturbance. In this paper, we derived a time series of major lake surface areas across Xinjiang Uygur Autonomous Region (XUAR), China, based [...] Read more.
Inland water bodies, which are critical freshwater resources for arid and semi-arid areas, are very sensitive to climate change and human disturbance. In this paper, we derived a time series of major lake surface areas across Xinjiang Uygur Autonomous Region (XUAR), China, based on an eight-day MODIS time series in 500 m resolution from 2000 to 2014. A classification approach based on water index and dynamic threshold selection was first developed to accommodate varied spectral features of water pixels at different temporal steps. The overall classification accuracy for a MODIS-derived water body is 97% compared to a water body derived using Landsat imagery. Then, monthly composites of water bodies were derived for the months of April, July, and September to identify seasonal patterns and inter-annual dynamics of 10 major lakes (>100 km2) in XUAR. Our results indicate that the changing trends of surface area of major lakes varied across the region. The surface areas of the Ebinur and Bosten Lakes showed a significant shrinking trend. The Ulungur-Jili Lake remained relatively stable during the entire period. For mountain lakes, the Barkol Lake showed a decreasing trend in April and July, but the Sayram Lake showed a significant expanding trend in September. The four plateau lakes exhibited significant expanding trends in all three seasons except for Arkatag Lake in July. The shrinking of major lakes reflects severe anthropogenic impacts due to agricultural and industrial needs, in addition to the impact of climate change. The pattern of lake changes across the XUAR can provide insight into the impact of climate change and human activities on regional water resources in this arid and semi-arid region. Full article
(This article belongs to the Special Issue Water Resource Variability and Climate Change)
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1818 KiB  
Article
Mitigating the Risk of Extreme Water Scarcity and Dependency: The Case of Jordan
by Joep F. Schyns, Arwa Hamaideh, Arjen Y. Hoekstra, Mesfin M. Mekonnen and Marlou Schyns
Water 2015, 7(10), 5705-5730; https://doi.org/10.3390/w7105705 - 21 Oct 2015
Cited by 45 | Viewed by 17357
Abstract
Jordan faces great internal water scarcity and pollution, conflict over trans-boundary waters, and strong dependency on external water resources through trade. This paper analyzes these issues and subsequently reviews options to reduce the risk of extreme water scarcity and dependency. Based on estimates [...] Read more.
Jordan faces great internal water scarcity and pollution, conflict over trans-boundary waters, and strong dependency on external water resources through trade. This paper analyzes these issues and subsequently reviews options to reduce the risk of extreme water scarcity and dependency. Based on estimates of water footprint, water availability, and virtual water trade, we find that groundwater consumption is nearly double the groundwater availability, water pollution aggravates blue water scarcity, and Jordan’s external virtual water import dependency is 86%. The review of response options yields 10 ingredients for a strategy for Jordan to mitigate the risks of extreme water scarcity and dependency. With respect to these ingredients, Jordan’s current water policy requires a strong redirection towards water demand management. Actual implementation of the plans in the national water strategy (against existing oppositions) would be a first step. However, more attention should be paid to reducing water demand by changing the consumption pattern of Jordanian consumers. Moreover, unsustainable exploitation of the fossil Disi aquifer should soon be halted and planned desalination projects require careful consideration regarding the sustainability of their energy supply. Full article
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791 KiB  
Article
Modeling Water-Quality Loads to the Reservoirs of the Upper Trinity River Basin, Texas, USA
by Taesoo Lee, Xiuying Wang, Michael White, Pushpa Tuppad, Raghavan Srinivasan, Balaji Narasimhan and Darrel Andrews
Water 2015, 7(10), 5689-5704; https://doi.org/10.3390/w7105689 - 20 Oct 2015
Cited by 8 | Viewed by 8071
Abstract
The Upper Trinity River Basin (TRB) is the most populated river basin and one of the largest water suppliers in Texas. However, sediment and nutrient loads are reducing the capacity of reservoirs and degrading water quality. The objectives of this study are to [...] Read more.
The Upper Trinity River Basin (TRB) is the most populated river basin and one of the largest water suppliers in Texas. However, sediment and nutrient loads are reducing the capacity of reservoirs and degrading water quality. The objectives of this study are to calibrate and validate the Soil and Water Assessment Tool (SWAT) model for ten study watersheds within the Upper TRB in order to assess nutrient loads into major reservoirs in the basin and to predict the effects of point source elimination and urbanization on nutrient loads through scenario analyses. SWAT performed reasonably well for the current condition except for two out of five tributaries in the Eagle Mountain watershed and total phosphorous OPEN ACCESS Water 2015, 7 5690 in Richland-Chambers. The impacts of simulated scenarios varied within watersheds. Point-source elimination achieved reductions ranging from 0.3% to 24% in total phosphorus and 1% to 56% in total nitrogen received by the reservoirs. Population and development projections were used to examine the impacts of urbanization on each watershed. Projected urbanization in 2030 had large effects on simulated total phosphorus loads in some watersheds, ranging from a reduction of 1% to an increase of 111%. Projected urbanization also affected simulated total nitrogen loads, from a reduction of 3% to an increase of 24%. One limitation of this study is the lack of long-term, up-to-date water quality data due to discontinued water-quality monitoring stations. Although careful considerations were given to the adjustment of parameter values reflecting various aspects of the nutrient processes, further data collection will enhance modeling study for assessment of these watersheds’ water resources and environmental problem. Full article
(This article belongs to the Special Issue Watershed Protection and Management)
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433 KiB  
Article
Optimal Choice of Soil Hydraulic Parameters for Simulating the Unsaturated Flow: A Case Study on the Island of Miyakojima, Japan
by Ken Okamoto, Kazuhito Sakai, Shinya Nakamura, Hiroyuki Cho, Tamotsu Nakandakari and Shota Ootani
Water 2015, 7(10), 5676-5688; https://doi.org/10.3390/w7105676 - 20 Oct 2015
Cited by 6 | Viewed by 5172
Abstract
We examined the influence of input soil hydraulic parameters on HYDRUS-1D simulations of evapotranspiration and volumetric water contents (VWCs) in the unsaturated zone of a sugarcane field on the island of Miyakojima, Japan. We first optimized the parameters for root water uptake and [...] Read more.
We examined the influence of input soil hydraulic parameters on HYDRUS-1D simulations of evapotranspiration and volumetric water contents (VWCs) in the unsaturated zone of a sugarcane field on the island of Miyakojima, Japan. We first optimized the parameters for root water uptake and examined the influence of soil hydraulic parameters (water retention curve and hydraulic conductivity) on simulations of evapotranspiration. We then compared VWCs simulated using measured soil hydraulic parameters with those using pedotransfer estimates obtained with the ROSETTA software package. Our results confirm that it is important to always use soil hydraulic parameters based on measured data, if available, when simulating evapotranspiration and unsaturated water flow processes, rather than pedotransfer functions. Full article
(This article belongs to the Special Issue Water Resource Variability and Climate Change)
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2750 KiB  
Article
Quantification of Environmental Flow Requirements to Support Ecosystem Services of Oasis Areas: A Case Study in Tarim Basin, Northwest China
by Jie Xue, Dongwei Gui, Ying Zhao, Jiaqiang Lei, Xinlong Feng, Fanjiang Zeng, Jie Zhou and Donglei Mao
Water 2015, 7(10), 5657-5675; https://doi.org/10.3390/w7105657 - 19 Oct 2015
Cited by 20 | Viewed by 6226
Abstract
Recently, a wide range of quantitative research on the identification of environmental flow requirements (EFRs) has been conducted. However, little focus is given to EFRs to maintain multiple ecosystem services in oasis areas. The present study quantifies the EFRs in oasis areas of [...] Read more.
Recently, a wide range of quantitative research on the identification of environmental flow requirements (EFRs) has been conducted. However, little focus is given to EFRs to maintain multiple ecosystem services in oasis areas. The present study quantifies the EFRs in oasis areas of Tarim Basin, Xinjiang, Northwest China on the basis of three ecosystem services: (1) maintenance of riverine ecosystem health, (2) assurance of the stability of oasis–desert ecotone and riparian (Tugai) forests, and (3) restoration of oasis–desert ecotone groundwater. The identified consumptive and non-consumptive water requirements are used to quantify and determine the EFRs in Qira oasis by employing the summation and compatibility rules (maximum principle). Results indicate that the annual maximum, medium, and minimum EFRs are 0.752 × 108, 0.619 × 108, and 0.516 × 108 m3, respectively, which account for 58.75%, 48.36%, and 40.29% of the natural river runoff. The months between April and October are identified as the most important periods to maintain the EFRs. Moreover, the water requirement for groundwater restoration of the oasis–desert ecotone accounts for a large proportion, representing 48.27%, 42.32%, and 37.03% of the total EFRs at maximum, medium, and minimum levels, respectively. Therefore, to allocate the integrated EFRs, focus should be placed on the water demand of the desert vegetation’s groundwater restoration, which is crucial for maintaining desert vegetation to prevent sandstorms and soil erosion. This work provides a reference to quantify the EFRs of oasis areas in arid regions. Full article
(This article belongs to the Special Issue Water Resources Assessment and Management in Drylands)
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1534 KiB  
Article
Runoff and Sediment Yield Variations in Response to Precipitation Changes: A Case Study of Xichuan Watershed in the Loess Plateau, China
by Tianhong Li and Yuan Gao
Water 2015, 7(10), 5638-5656; https://doi.org/10.3390/w7105638 - 19 Oct 2015
Cited by 21 | Viewed by 7099
Abstract
The impacts of climate change on hydrological cycles and water resource distribution is particularly concerned with environmentally vulnerable areas, such as the Loess Plateau, where precipitation scarcity leads to or intensifies serious water related problems including water resource shortages, land degradation, and serious [...] Read more.
The impacts of climate change on hydrological cycles and water resource distribution is particularly concerned with environmentally vulnerable areas, such as the Loess Plateau, where precipitation scarcity leads to or intensifies serious water related problems including water resource shortages, land degradation, and serious soil erosion. Based on a geographical information system (GIS), and using gauged hydrological data from 2001 to 2010, digital land-use and soil maps from 2005, a Soil and Water Assessment Tool (SWAT) model was applied to the Xichuan Watershed, a typical hilly-gullied area in the Loess Plateau, China. The relative error, coefficient of determination, and Nash-Sutcliffe coefficient were used to analyze the accuracy of runoffs and sediment yields simulated by the model. Runoff and sediment yield variations were analyzed under different precipitation scenarios. The increases in runoff and sediment with increased precipitation were greater than their decreases with reduced precipitation, and runoff was more sensitive to the variations of precipitation than was sediment yield. The coefficients of variation (CVs) of the runoff and sediment yield increased with increasing precipitation, and the CV of the sediment yield was more sensitive to small rainfall. The annual runoff and sediment yield fluctuated greatly, and their variation ranges and CVs were large when precipitation increased by 20%. The results provide local decision makers with scientific references for water resource utilization and soil and water conservation. Full article
(This article belongs to the Special Issue Water Resource Variability and Climate Change)
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822 KiB  
Article
Bayesian Network Modeling to Improve Water Pricing Practices in Northwest China
by Yusuyunjiang Mamitimin, Til Feike and Reiner Doluschitz
Water 2015, 7(10), 5617-5637; https://doi.org/10.3390/w7105617 - 19 Oct 2015
Cited by 23 | Viewed by 6254
Abstract
Water pricing is regarded as the most important and simplest economic instrument to encourage more efficient use of irrigation water in crop production. In the extremely water-scarce Tarim River basin in northwest China, improving water use efficiency has high relevance for research and [...] Read more.
Water pricing is regarded as the most important and simplest economic instrument to encourage more efficient use of irrigation water in crop production. In the extremely water-scarce Tarim River basin in northwest China, improving water use efficiency has high relevance for research and policy. A Bayesian network modeling approach was applied, which is especially suitable under data-scarce conditions and the complex geo-hydrological, socioeconomic, and institutional settings of the study region, as it allows the integration of data from various types of sources. The transdisciplinary approach aimed at understanding the actual water pricing practices, the shortcomings of the current system, and possible ways of improvement. In an iterative procedure of expert interviews and group workshops, the key factors related to water pricing and water use efficiency were identified. The interactions among specific factors were defined by the respective experts, generating a causal network, which describes all relevant aspects of the investigated system. This network was finally populated with probabilistic relationships through a second round of expert interviews and group discussions. The Bayesian modeling exercise was then conducted using Netica software. The modeling results show that the mere increase of water price does not lead to significant increases in water use efficiency in crop production. Additionally, the model suggests a shift to volumetric water pricing, subsidization of water saving irrigation technology, and advancing agricultural extension to enable the farmer to efficiently react to increased costs for water. The applied participatory modeling approach helped to stimulate communication among relevant stakeholders from different domains in the region, which is necessary to create mutual understanding and joint targeted action. Finally, the challenges related to the applied transdisciplinary Bayesian modeling approach are discussed in the Chinese context. Full article
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1868 KiB  
Article
Towards A New Decision Support System for Design, Management and Operation of Wastewater Treatment Plants for the Reduction of Greenhouse Gases Emission
by Donatella Caniani, Giovanni Esposito, Riccardo Gori and Giorgio Mannina
Water 2015, 7(10), 5599-5616; https://doi.org/10.3390/w7105599 - 16 Oct 2015
Cited by 30 | Viewed by 11222
Abstract
The increasing attention paid to the environment has led to a reduction in the emissions from wastewater treatment plants (WWTPs). Moreover, the increasing interest in the greenhouse gas (GHG) emissions from WWTPs suggests that we reconsider the traditional tools used for designing and [...] Read more.
The increasing attention paid to the environment has led to a reduction in the emissions from wastewater treatment plants (WWTPs). Moreover, the increasing interest in the greenhouse gas (GHG) emissions from WWTPs suggests that we reconsider the traditional tools used for designing and managing WWTPs. Indeed, nitrous oxide, carbon dioxide and methane can be emitted from wastewater treatment, significantly contributing to the greenhouse gas (GHG) footprint. The reduction of energy consumption as well as GHG emission are of particular concern for large WWTPs which treat the majority of wastewater in terms of both volume and pollution load. Nowadays, there is an increasing need to develop new tools that include additional performance indicators related to GHG emissions and energy consumption as well as traditional effluent quality parameters. Energy consumption, in fact, can be considered as an indirect source of GHGs. This paper presents the development of an ongoing research project aiming at setting-up an innovative mathematical model platform for the design and management of WWTPs. The final goal of the project by means of this platform is to minimize the environmental impact of WWTPs through their optimization in terms of energy consumptions and emissions, which can be regarded as discharged pollutants, sludge and GHGs. Full article
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172 KiB  
Editorial
Impact of Ocean Acidification on Marine Organisms—Unifying Principles and New Paradigms
by Jason M. Hall-Spencer, Mike Thorndyke and Sam Dupont
Water 2015, 7(10), 5592-5598; https://doi.org/10.3390/w7105592 - 15 Oct 2015
Cited by 10 | Viewed by 7177
Abstract
This special issue combines original research with seminal reviews of the biological impact of ocean acidification. The ten contributions cover a wide range of topics from chemical and biological responses to increased CO2 and decreased pH to socio-economical sensitivities and adaptation options. [...] Read more.
This special issue combines original research with seminal reviews of the biological impact of ocean acidification. The ten contributions cover a wide range of topics from chemical and biological responses to increased CO2 and decreased pH to socio-economical sensitivities and adaptation options. Overall, this special issue also highlights the key knowledge gaps and future challenges. These include the need to develop research strategy and experiments that factor in evolution, incorporate natural variability in physical conditions (e.g., pH, temperature, oxygen, food quality and quantity) and ecological interactions. The research presented in this special issue demonstrates the need to study more habitats (e.g., coastal, deep sea) and prioritize species of ecological or economic significance. Full article
3387 KiB  
Article
Assessing the Performance of In-Stream Restoration Projects Using Radio Frequency Identification (RFID) Transponders
by Bruce MacVicar, Margot Chapuis, Emma Buckrell and André Roy
Water 2015, 7(10), 5566-5591; https://doi.org/10.3390/w7105566 - 15 Oct 2015
Cited by 30 | Viewed by 6416
Abstract
Instream channel restoration is a common practice in river engineering that presents a challenge for research. One research gap is the development of monitoring techniques that allow for testable predictions of sediment transport and supply. Here we use Radio Frequency Identification (RFID) transponders [...] Read more.
Instream channel restoration is a common practice in river engineering that presents a challenge for research. One research gap is the development of monitoring techniques that allow for testable predictions of sediment transport and supply. Here we use Radio Frequency Identification (RFID) transponders to compare the short-term (1-year) sediment transport response to flood events in a restored and a control reach. The field site is Wilket Creek, an enlarged creek in a fully urbanized catchment without stormwater management control in Toronto, Ontario. The responses to three flooding periods, each of which are at or above the design bankfull discharge, are described. Key results are that (i) particle mobility is lower in the restored reach for all three periods; (ii) full mobility occurs in the control reach during the first two floods while partial mobility occurs in the restored reach; and (iii) the constructed morphology exerted a controlling influence on particle entrainment, with higher mobility in the pools. Log-transformed travel distances exhibit normal distributions when grouped by particle size class, which allows a statistical comparison with power law and other predictive travel-distance relations. Results show that three bedload transport conditions can occur, with partial mobility associated with a mild relation between particle size and travel distance and full mobility associated with either a flat or steep relation depending on the degree of integration of particles in the bed. Recommendations on seeding strategy and sample sizes are made to improve the precision of the results by minimizing confidence intervals for mobility and travel distances. Even in a short term study, the RFID sediment tracking technique allows a process-based assessment of stream restoration outcomes that can be used to justify the instream intervention and plan future attempts to stabilize and enhance the system. Full article
(This article belongs to the Special Issue Recent Advances in Riverflow Research)
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2004 KiB  
Article
Understanding Groundwater Storage Changes and Recharge in Rajasthan, India through Remote Sensing
by Pennan Chinnasamy, Basant Maheshwari and Sanmugam Prathapar
Water 2015, 7(10), 5547-5565; https://doi.org/10.3390/w7105547 - 15 Oct 2015
Cited by 53 | Viewed by 19982
Abstract
Groundwater management practices need to take hydrogeology, the agro-climate and demand for groundwater into account. Since agroclimatic zones have already been demarcated by the Government of India, it would aid policy makers to understand the status of groundwater recharge and discharge in each [...] Read more.
Groundwater management practices need to take hydrogeology, the agro-climate and demand for groundwater into account. Since agroclimatic zones have already been demarcated by the Government of India, it would aid policy makers to understand the status of groundwater recharge and discharge in each agroclimatic zone. However, developing effective policies to manage groundwater at agroclimatic zone and state levels is constrained due to a paucity of temporal data and information. With the launch of the Gravity Recovery and Climate Experiment (GRACE) mission in 2002, it is now possible to obtain frequent data at broad spatial scales and use it to examine past trends in rain induced recharge and groundwater use. In this study, the GRACE data were used to estimate changes to monthly total water storage (TWS) and groundwater storage in different agroclimatic zones of Rajasthan, India. Furthermore, the long-term annual and seasonal groundwater storage trends in the state were estimated using the GRACE data and the trends were compared with those in rainfall data. The methodology based on GRACE data was found to be useful in detecting large scale trends in groundwater storage changes covering different agroclimatic zones. The analysis of data shows that groundwater storage trends depend on rainfall in previous years and, therefore, on the antecedent moisture conditions. Overall, the study indicates that if suitable groundwater recharge methods and sites are identified for the state, there is potential to achieve more groundwater recharge than what is currently occurring and, thus, enhancing the availability of water for irrigated agriculture. Full article
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1903 KiB  
Article
Effects of Seasonal Thermal Stratification on the Functional Diversity and Composition of the Microbial Community in a Drinking Water Reservoir
by Xiao Yang, Tinglin Huang and Haihan Zhang
Water 2015, 7(10), 5525-5546; https://doi.org/10.3390/w7105525 - 15 Oct 2015
Cited by 49 | Viewed by 8254
Abstract
The microbial communities within reservoir ecosystems are shaped by water quality and hydrological characteristics. However, there are few studies focused on the effects of thermal stratification on the bacterial community diversity in drinking water reservoirs. In this study, we collected water samples from [...] Read more.
The microbial communities within reservoir ecosystems are shaped by water quality and hydrological characteristics. However, there are few studies focused on the effects of thermal stratification on the bacterial community diversity in drinking water reservoirs. In this study, we collected water samples from the Jinpen Reservoir around the re-stratification period. To explore the functional diversity and bacterial community composition, we used the Biolog method and 16S rRNA-based 454 pyrosequencing combined with flow cytometry. The results indicated that stratification of the reservoir had great effects on temperature and oxygen profiles, and both the functional diversity and the composition of the bacterial community strongly reflected the significant vertical stratification in the reservoir. The results of the Biolog method showed a significantly higher utilization of carbon sources in the hypolimnion than in the epilimnion. The result of pyrosequencing also showed a significantly higher species diversity and richness in the hypolimnion than in the epilimnion with different dominant phylum. Redundancy analysis also indicated that the majority of environmental variables, especially pH and dissolved oxygen, played key roles in shaping bacterial community composition. Our study provides a better understanding of the functional diversity of bacterial communities, and the response of microorganisms to seasonal thermal stratification. Full article
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657 KiB  
Article
Conditional Order-m Efficiency of Wastewater Treatment Plants: The Role of Environmental Factors
by Ramón Fuentes, Teresa Torregrosa and Enrique Ballenilla
Water 2015, 7(10), 5503-5524; https://doi.org/10.3390/w7105503 - 15 Oct 2015
Cited by 24 | Viewed by 5951
Abstract
The growing economic and environmental importance of managing water resources at a global level also entails greater efforts and interest in improving the functioning and efficiency of the increasingly more numerous wastewater treatment plants (WWTPs). In this context, this study analyzes the efficiency [...] Read more.
The growing economic and environmental importance of managing water resources at a global level also entails greater efforts and interest in improving the functioning and efficiency of the increasingly more numerous wastewater treatment plants (WWTPs). In this context, this study analyzes the efficiency of a uniform sample of plants of this type located in the region of Valencia (Spain). The type of efficiency measure used for this (conditional order-m efficiency) allows continuous and discrete contextual variables to be directly involved in the analysis and enables the assessment of their statistical significance and effect (positive or negative). The main findings of the study showed that the quality of the influent water and also the size and age of the plants had a significant influence on their efficiency levels. In particular, as regards the effect of such variables, the findings pointed to the existence of an inverse relationship between the quality of the influent water and the efficiency of the WWTPs. Also, a lower annual volume of treated water and more modern installations showed a positive influence. Additionally, the average efficiency levels observed turned out to be higher than those reported in previous studies. Full article
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890 KiB  
Article
A Modified van Genuchten-Mualem Model of Hydraulic Conductivity in Korean Residual Soils
by Seboong Oh, Yun Ki Kim and Jun-Woo Kim
Water 2015, 7(10), 5487-5502; https://doi.org/10.3390/w7105487 - 15 Oct 2015
Cited by 17 | Viewed by 11390
Abstract
According to the Mualem capillary model, hydraulic conductivity (HC) is integrated theoretically from the function related to soil water retention curves (SWRC). On the other hand, based on the smooth type of SWRC, the predicted HC function decreases abruptly near saturation, which often [...] Read more.
According to the Mualem capillary model, hydraulic conductivity (HC) is integrated theoretically from the function related to soil water retention curves (SWRC). On the other hand, based on the smooth type of SWRC, the predicted HC function decreases abruptly near saturation, which often challenges the stability of numerical solutions. To improve the Mualem HC, van Genuchten’s function for SWRC was modified within the range of low matric suction. The van Genuchten-Mualem HC was then modified to integrate the proposed SWRC for each interval decomposed by a tangential curve. The analytical solutions of the modified HC were derived to prevent an abrupt decrease near saturation. The SWRC and HC data were acquired from laboratory tests for unsaturated soils sampled from five areas in Korea. The results of the HC tests were compared with the theoretical HC models using both the van Genuchten SWRCs and the modified curves. For fine grained soils, the modified model predicts a saturated HC at very small suctions. Furthermore, the modified model was shown to accurately predict the unsaturated behavior of the HC functions for Korean weathered soils. Full article
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2177 KiB  
Article
Using the SPEI to Assess Recent Climate Change in the Yarlung Zangbo River Basin, South Tibet
by Binquan Li, Wei Zhou, Yaoyang Zhao, Qin Ju, Zhongbo Yu, Zhongmin Liang and Kumud Acharya
Water 2015, 7(10), 5474-5486; https://doi.org/10.3390/w7105474 - 15 Oct 2015
Cited by 49 | Viewed by 7746
Abstract
The Yarlung Zangbo River (YZR) is the largest river system in the Tibetan Plateau, and its basin is one of the centers of human economic activity in Tibet. Large uncertainties exist in several previous climate change studies in this basin because of limited [...] Read more.
The Yarlung Zangbo River (YZR) is the largest river system in the Tibetan Plateau, and its basin is one of the centers of human economic activity in Tibet. Large uncertainties exist in several previous climate change studies in this basin because of limited climate observations. In this paper, we used a meteorological drought index (Standardized Precipitation Evapotranspiration Index, SPEI) and a newly-released gridded climate forcing dataset based on high-quality climate station data to re-evaluate climate change in the YZR Basin during the period of 1961–2014. Results showed that precipitation experienced a statistically insignificant increasing trend at a rate of 6.32 mm/10 years, and its annual mean was 512.40 mm. The basin was sensitive to climate change in terms of the air temperature that significantly increased at the rate of 0.32 °C/10 years. This warming rate was obviously larger than that in many other regions. Analysis of SPEI showed that the basin had no obvious statistical trends in the number of dry/wet episodes, but the severity of dry episode aggravated in terms of duration and magnitude. This study provides a reliable analysis of climate change in the YZR Basin, and suggests this large Tibetan river basin is sensitive to climate change. Full article
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6095 KiB  
Article
Assessing Nonstationary Spatial Patterns of Extreme Droughts from Long-Term High-Resolution Observational Dataset on a Semiarid Basin (Spain)
by Sandra G. Garcia Galiano, Patricia Olmos Gimenez and Juan Diego Giraldo-Osorio
Water 2015, 7(10), 5458-5473; https://doi.org/10.3390/w7105458 - 14 Oct 2015
Cited by 20 | Viewed by 5433
Abstract
In basins of South-eastern Spain; such as the semiarid Segura River Basin (SRB), a strong decrease in runoff from the end of the 1970s has been observed. However, in the SRB the decreasing trend is not only related with climate variability and change, [...] Read more.
In basins of South-eastern Spain; such as the semiarid Segura River Basin (SRB), a strong decrease in runoff from the end of the 1970s has been observed. However, in the SRB the decreasing trend is not only related with climate variability and change, also with intensive reforestation aimed at halting desertification and erosion, whichever the reason is, the default assumption of stationarity in water resources systems cannot be guaranteed. Therefore there is an important need for improvement in the ability of monitoring and predicting the impacts associated with the change of hydrologic regimes. It is thus necessary to apply non-stationary probabilistic models, which are able to reproduce probability density functions whose parameters vary with time. From a high-resolution daily gridded rainfall dataset of more than five decades (1950−2007), the spatial distribution of lengths of maximum dry spells for several thresholds are assessed, applying Generalized Additive Models for Location Scale and Shape (GAMLSS) models at the grid site. Results reveal an intensification of extreme drought events in some headbasins of the SRB important for water supply. The identification of spatial patterns of drought hazards at basin scale, associated with return periods; contribute to designing strategies of drought contingency preparedness and recovery operations, which are the leading edge of adaptation strategies. Full article
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745 KiB  
Article
Sustainable Supply of Safe Drinking Water for Underserved Households in Kenya: Investigating the Viability of Decentralized Solutions
by Pauline Chepchirchir Cherunya, Christine Janezic and Michael Leuchner
Water 2015, 7(10), 5437-5457; https://doi.org/10.3390/w7105437 - 14 Oct 2015
Cited by 16 | Viewed by 11362
Abstract
Water quality and safe water sources are pivotal aspects of consideration for domestic water. Focusing on underserved households in Kenya, this study compared user perceptions and preferences on water-service provision options, particularly investigating the viability of decentralized models, such as the Safe Water [...] Read more.
Water quality and safe water sources are pivotal aspects of consideration for domestic water. Focusing on underserved households in Kenya, this study compared user perceptions and preferences on water-service provision options, particularly investigating the viability of decentralized models, such as the Safe Water Enterprise (SWE), as sustainable safe drinking water sources. Results showed that among a number of water-service provision options available, the majority of households regularly sourced their domestic water from more than one source (86% Ngoliba/Maguguni, 98% Kangemi Gichagi). A majority of households perceived their water sources to be unsafe to drink (84% Ngoliba/Maguguni, 73% Kangemi Gichagi). For this reason, drinking water was mainly chlorinated (48% Ngoliba/Maguguni, 33% Kangemi Gichagi) or boiled (42% Ngoliba/Maguguni, 67% Kangemi Gichagi). However, this study also found that households in Kenya did not apply these household water treatment methods consistently, thus indicating inconsistency in safe water consumption. The SWE concept, a community-scale decentralized safe drinking water source, was a preferred option among households who perceived it to save time and to be less cumbersome as compared to boiling and chlorination. Willingness to pay for SWE water was also a positive indicator for its preference by the underserved households. However, the long-term applicability of such decentralized water provision models needs to be further investigated within the larger water-service provision context. Full article
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1012 KiB  
Article
Water-Energy-Food Nexus in a Transboundary River Basin: The Case of Tonle Sap Lake, Mekong River Basin
by Marko Keskinen, Paradis Someth, Aura Salmivaara and Matti Kummu
Water 2015, 7(10), 5416-5436; https://doi.org/10.3390/w7105416 - 12 Oct 2015
Cited by 79 | Viewed by 16576
Abstract
The water-energy-food nexus is promoted as a new approach for research and policy-making. But what does the nexus mean in practice and what kinds of benefits does it bring? In this article we share our experiences with using a nexus approach in Cambodia’s [...] Read more.
The water-energy-food nexus is promoted as a new approach for research and policy-making. But what does the nexus mean in practice and what kinds of benefits does it bring? In this article we share our experiences with using a nexus approach in Cambodia’s Tonle Sap Lake area. We conclude that water, energy and food security are very closely linked, both in the Tonle Sap and in the transboundary Mekong River Basin generally. The current drive for large-scale hydropower threatens water and food security at both local and national scales. Hence, the nexus provides a relevant starting point for promoting sustainable development in the Mekong. We also identify and discuss two parallel dimensions for the nexus, with one focusing on research and analysis and the other on integrated planning and cross-sectoral collaboration. In our study, the nexus approach was particularly useful in facilitating collaboration and stakeholder engagement. This was because the nexus approach clearly defines the main themes included in the process, and at the same time widens the discussion from mere water resource management into the broader aspects of water, energy and food security. Full article
(This article belongs to the Special Issue Water-Energy-Food Nexus in Large Asian River Basins)
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228 KiB  
Article
Water-Energy-Food Nexus within the Framework of International Water Law
by Antti Belinskij
Water 2015, 7(10), 5396-5415; https://doi.org/10.3390/w7105396 - 12 Oct 2015
Cited by 31 | Viewed by 7061
Abstract
International water law, which regulates the uses of international watercourses that are situated partly in different States, is a highly topical sector of law. In 2014, two conventions covering the subject matter entered into force globally. At the same time, a water-food-energy nexus [...] Read more.
International water law, which regulates the uses of international watercourses that are situated partly in different States, is a highly topical sector of law. In 2014, two conventions covering the subject matter entered into force globally. At the same time, a water-food-energy nexus has become part and parcel of the development canon that emphasises the importance of the complex relationship between water, energy and food. In this article, it is discussed whether international water law supports the water-food-energy nexus approach, which aims to reconcile the different water uses in international basins. The analysis also covers the human rights to water and food from the nexus viewpoint. The legal regime of the Mekong River is used as an example of the possibilities and challenges of the nexus approach in international water law. It is concluded that despite its deficiencies international water law provides a very useful platform for the cooperation between States and different sectors that aim at guaranteeing water, food and energy security. Full article
(This article belongs to the Special Issue Water-Energy-Food Nexus in Large Asian River Basins)
1170 KiB  
Article
Effect of Submergence and Apron Length on Spillway Scour: Case Study
by Seungho Hong, Celio Biering, Terry W. Sturm, Kwang Seok Yoon and Juan A. Gonzalez-Castro
Water 2015, 7(10), 5378-5395; https://doi.org/10.3390/w7105378 - 12 Oct 2015
Cited by 10 | Viewed by 8651
Abstract
Large-scale water resources systems are often managed by an integrated set of hydraulic structures that are vulnerable to wider ranges of discharge and tailwater elevation than envisioned in their original design due to climate change and additional project objectives such as fostering healthy [...] Read more.
Large-scale water resources systems are often managed by an integrated set of hydraulic structures that are vulnerable to wider ranges of discharge and tailwater elevation than envisioned in their original design due to climate change and additional project objectives such as fostering healthy ecosystems. The present physical model study explored the performance of a spillway structure on the Kissimmee River, operated by the South Florida Water Management District, under extreme conditions of drought and flooding with accompanying low and high tailwater levels for both gate-controlled and uncontrolled spillway flow conditions. Maximum scour depths and their locations for two different riprap apron lengths downstream of the spillway stilling basin were measured along with the complex flow fields prior to scour. Effects of tailwater submergence, type of spillway flow and riprap apron length on scour results are interpreted in terms of the measured turbulent kinetic energy and velocity distributions near the bed. Full article
(This article belongs to the Special Issue Recent Advances in Riverflow Research)
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540 KiB  
Article
Catchment-Scale Modeling of Nitrogen Dynamics in a Temperate Forested Watershed, Oregon. An Interdisciplinary Communication Strategy
by Kellie Vaché, Lutz Breuer, Julia Jones and Phil Sollins
Water 2015, 7(10), 5345-5377; https://doi.org/10.3390/w7105345 - 12 Oct 2015
Cited by 2 | Viewed by 5280
Abstract
We present a systems modeling approach to the development of a place-based ecohydrological model. The conceptual model is calibrated to a variety of existing observations, taken in watershed 10 (WS10) at the HJ Andrews Experimental Forest (HJA) in Oregon, USA, a long term [...] Read more.
We present a systems modeling approach to the development of a place-based ecohydrological model. The conceptual model is calibrated to a variety of existing observations, taken in watershed 10 (WS10) at the HJ Andrews Experimental Forest (HJA) in Oregon, USA, a long term ecological research (LTER) site with a long history of catchment-scale data collection. The modeling framework was designed to help document and evaluate an evolving understanding of catchment processing of water, nitrogen, and carbon that has developed over the many years of on-going research at the site. We use the dynamic model to capture the temporal variation in the N and C budgets and to evaluate how different components of the complex system may control the retention and release of N in this pristine forested landscape. Results indicate that the relative roles of multiple competing controls on N change seasonally, between periods of wet/dry and growth/senescence. The model represents a communication strategy to facilitate dialog between disciplinary experimentalists and modelers, to produce a more complete picture of nitrogen cycling in the region. We view this explicit development of complete, yet conceptually simplified models as a useful and important way to evaluate complex environmental dynamics. Full article
(This article belongs to the Special Issue Hydro-Ecological Modeling)
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1432 KiB  
Article
Optimizing Water Allocation under Uncertain System Conditions in Alfeios River Basin (Greece), Part A: Two-Stage Stochastic Programming Model with Deterministic Boundary Intervals
by Eleni Bekri, Markus Disse and Panayotis Yannopoulos
Water 2015, 7(10), 5305-5344; https://doi.org/10.3390/w7105305 - 9 Oct 2015
Cited by 11 | Viewed by 6944
Abstract
The enactment of the Water Framework Directive, constituting the basis of the European water policy, introduced various challenges and complexities for water resources management. River basins are exposed to a plethora of environmental stresses, resulting in degradation of their quantitative and qualitative status. [...] Read more.
The enactment of the Water Framework Directive, constituting the basis of the European water policy, introduced various challenges and complexities for water resources management. River basins are exposed to a plethora of environmental stresses, resulting in degradation of their quantitative and qualitative status. This led to the reduction of clean available water, increasing competition among water users and imposing the need for optimal water allocation for each river unit. In most countries (including those in the Mediterranean), water resources management is characterized by lack of effective operational strategies combined with the absence of permanent measuring systems and low financial means, hampering the implementation of efficient river monitoring. Therefore, water resources management is indicated by high uncertainty and by imprecise and limited data, which may be easily approximated through estimates of intervals. In the present work, optimal water allocation under uncertain system conditions is undertaken for the Alfeios River Basin (Greece) based on an inexact two-stage stochastic programming methodology developed by Huang and Loucks (2000). It combines ordinary two-stage stochastic programming with uncertainties expressed as deterministic boundary intervals. Stable intervals for optimized water allocation targets and probabilistic water allocation and shortages are estimated under a baseline scenario and four water and agricultural policy future scenarios. Full article
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377 KiB  
Article
Empirical Formulas for Calculation of Negative Pressure Difference in Vacuum Pipelines
by Marek Kalenik
Water 2015, 7(10), 5284-5304; https://doi.org/10.3390/w7105284 - 9 Oct 2015
Cited by 11 | Viewed by 8101
Abstract
The paper presents the analysis of results of empirical investigations of a negative pressure difference in vacuum pipelines with internal diameters of 57, 81, 102 mm. The investigations were performed in an experimental installation of a vacuum sewage system, built in a laboratory [...] Read more.
The paper presents the analysis of results of empirical investigations of a negative pressure difference in vacuum pipelines with internal diameters of 57, 81, 102 mm. The investigations were performed in an experimental installation of a vacuum sewage system, built in a laboratory hall on a scale of 1:1. The paper contains a review of the literature concerning two-phase flows (liquid-gas) in horizontal, vertical and diagonal pipelines. It presents the construction and working principles of the experimental installation of vacuum sewage system in steady and unsteady conditions during a two-phase flow of water and air. It also presents a methodology for determination of formula for calculation of a negative pressure difference in vacuum pipelines. The results obtained from the measurements of the negative pressure difference Δpvr in the vacuum pipelines were analyzed and compared with the results of calculations of the negative pressure difference Δpvr, obtained from the determined formula. The values of the negative pressure difference Δpvr calculated for the vacuum pipelines with internal diameters of 57, 81, and 102 mm with the use of Formula (19) coincide with the values of Δpvr measured in the experimental installation of a vacuum sewage system. The dependence of the negative pressure difference Δpvr along the length of the vacuum pipelines on the set negative pressure in the vacuum container pvzp is linear. The smaller the vacuum pipeline diameter, the greater the negative pressure difference Δpvr is along its length. Full article
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886 KiB  
Article
Microbiological Confinement of Two Adjacent Water Wells in Lake Karla Basin, Greece
by Konstantinos Ar. Kormas, Alexandra Meziti and Theodoti Papadimitriou
Water 2015, 7(10), 5272-5283; https://doi.org/10.3390/w7105272 - 30 Sep 2015
Viewed by 5036
Abstract
We analyzed the bacterial and archaeal community structure of two adjacent irrigation well waters of the Lake Karla Basin, Central Greece, in order to elucidate their connectivity or confinement by using 454 tag pyrosequencing of the 16S rRNA genes. Although considerable overlap was [...] Read more.
We analyzed the bacterial and archaeal community structure of two adjacent irrigation well waters of the Lake Karla Basin, Central Greece, in order to elucidate their connectivity or confinement by using 454 tag pyrosequencing of the 16S rRNA genes. Although considerable overlap was found at the phylum/high taxonomic level, and also at the operational taxonomic units (OTU) level, the dominant, and most likely active, prokaryotes represented by these OTUs were very different between the two wells. As expected, we found higher bacterial species richness compared to that of archaeal, and this renders Bacteria better for the study of connectivity or confinement of water wells. Some of the taxonomic groups found are amongst those found typically in the terrestrial subsurface and also those that have been recently described, enhancing the importance of the subsurface for expanding our knowledge on microbial diversity. The majority of the archaeal and several of the bacterial OTUs, including the most dominant ones in each well, were related to marine or saline environments, indicating the previously suggested persistence of fertilizer residuals in the basin’s soils. Full article
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