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Water, Volume 10, Issue 3 (March 2018)

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Cover Story (view full-size image) Water storage tanks atop Jordanian homes attest to the long piped water supply interruptions in the [...] Read more.
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Open AccessArticle Exploring the Role of Relational Practices in Water Governance Using a Game-Based Approach
Water 2018, 10(3), 346; https://doi.org/10.3390/w10030346
Received: 22 January 2018 / Revised: 9 March 2018 / Accepted: 13 March 2018 / Published: 20 March 2018
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Abstract
The growing complexity and interdependence of water management processes requires the involvement of multiple stakeholders in water governance. Multi-party collaboration is increasingly vital at both the strategy development and implementation levels. Multi-party collaboration involves a process of joint decision-making among key stakeholders in
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The growing complexity and interdependence of water management processes requires the involvement of multiple stakeholders in water governance. Multi-party collaboration is increasingly vital at both the strategy development and implementation levels. Multi-party collaboration involves a process of joint decision-making among key stakeholders in a problem domain directed towards the future of that domain. However, the common goal is not present from the beginning; rather, the common goal emerges during the process of collaboration. Unfortunately, when the conflicting interests of different actors are at stake, the large majority of environmental multi-party efforts often do not reliably deliver sustainable improvements to policy and/or practice. One of the reasons for this, which has been long established by many case studies, is that social learning with a focus on relational practices is missing. The purpose of this paper is to present the design and initial results of a pilot study that utilized a game-based approach to explore the effects of relational practices on the effectiveness of water governance. This paper verifies the methods used by addressing the following question: are game mechanisms, protocols for facilitation and observation, the recording of decisions and results, and participant surveys adequate to reliably test hypotheses about behavioral decisions related to water governance? We used the “Lords of the Valley” (LOV) game, which focuses on the local-level management of a hypothetical river valley involving many stakeholders. We used an observation protocol to collect data on the quality of relational practices and compared this data with the quantitative outcomes achieved by participants in the game. In this pilot study, we ran the game three times with different groups of participants, and here we provide the outcomes within the context of verifying and improving the methods. Full article
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Open AccessArticle Effects of Drip Irrigation Models on Chemical Clogging under Saline Water Use in Hetao District, China
Water 2018, 10(3), 345; https://doi.org/10.3390/w10030345
Received: 26 January 2018 / Revised: 16 March 2018 / Accepted: 16 March 2018 / Published: 20 March 2018
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Abstract
Saline water is a major resource for agricultural irrigation in arid-semi arid regions, especially when it is combined with drip irrigation. However, highly saline water can easily cause clogging of the emitters in drip irrigation systems, adversely affecting crop growth. Hence, a 2a
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Saline water is a major resource for agricultural irrigation in arid-semi arid regions, especially when it is combined with drip irrigation. However, highly saline water can easily cause clogging of the emitters in drip irrigation systems, adversely affecting crop growth. Hence, a 2a processing tomatoes drip irrigation study was conducted in Hetao irrigation district. The chemical clogging of the emitters was analyzed using four drip irrigation models: RI1 (all fresh water irrigation), RI2 (saline water use in the flowering stage, fresh water in the fruiting stage), RI3 (fresh water use in the flowering stage, saline water in the fruiting stage), and RI4 (all saline water irrigation). The results revealed that the discharge ratio variation (Dra) and the Christiansen uniformity coefficient (CU) of RI4 decreased to 74.0% and 70.9%, respectively, which is considered as a clogged condition with poor irrigation uniformity. When compared to the all saline water irrigation model, the Dra and CU of fresh-saline alternating irrigation models (RI2 and RI3) were higher by 12.16% and 18.05%, respectively. Additionally, the dry weight (DW) of emitters fouling was less than that of RI4 by 16.30%. The Dra and CU showed linear relationships (R2 > 0.79) for the different irrigation models. However, as the Dra declined, the more adverse influence on maintaining the high CU was found in RI4. Using irrigation models with alternating fresh-saline water were recommended to control chemical clogging in drip irrigation systems. Calcium carbonate (CaCO3) was the dominant scale formed, which caused the emitters to clog when processing tomatoes were grown using a drip irrigation system with saline water. Full article
(This article belongs to the Special Issue Data-Driven Methods for Agricultural Water Management)
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Open AccessArticle The Magnitude and Cost of Groundwater Metering and Control in Agriculture
Water 2018, 10(3), 344; https://doi.org/10.3390/w10030344
Received: 8 February 2018 / Revised: 14 March 2018 / Accepted: 16 March 2018 / Published: 20 March 2018
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Abstract
Volumetric pricing as envisaged within the Water Framework Directive (60/2000) is a considerable challenge in terms of irrigation in Mediterranean regions, since a large share of the water source is groundwater. Enforcing this pricing scheme involves systematic metering and control (M&C) systems with
[...] Read more.
Volumetric pricing as envisaged within the Water Framework Directive (60/2000) is a considerable challenge in terms of irrigation in Mediterranean regions, since a large share of the water source is groundwater. Enforcing this pricing scheme involves systematic metering and control (M&C) systems with subsequent high costs. This paper aims to fill the gap in the literature related to the assessment of costs for the metering and control of irrigation groundwater. The full operational cost of all activities related to the hypothetical services provided by a public agency is assessed for Apulia (a region in southern Italy). The results show that point-to-point metering services are quite costly, ranging from 38.5 to 59 euros per delivery point. New questions arise regarding whether the M&C of groundwater abstraction should be fully charged to end users (i.e., farmers), or also shared with the whole society as a public service aimed at environmental enhancement. Full article
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Open AccessArticle Trading Natural Riparian Forests for Urban Shelterbelt Plantations—A Sustainability Assessment of the Kökyar Protection Forest in NW China
Water 2018, 10(3), 343; https://doi.org/10.3390/w10030343
Received: 6 August 2017 / Revised: 1 March 2018 / Accepted: 8 March 2018 / Published: 20 March 2018
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Abstract
Cities at the fringe of the Taklimakan desert in NW China are prone to dust and sand storms with serious consequences for human well-being. The Kökyar Protection Forest was established in the 1980s as an ecological engineering project with the intent of protecting
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Cities at the fringe of the Taklimakan desert in NW China are prone to dust and sand storms with serious consequences for human well-being. The Kökyar Protection Forest was established in the 1980s as an ecological engineering project with the intent of protecting the city of Aksu, NW China, from these impacts. It is designed as a combination of poplar shelterbelts and orchards, irrigated by river water from the Aksu River, the main tributary of the Tarim River. Prevalent literature describes it as an afforestation project for combatting desertification with manifold positive effects for the economic, social, and environmental dimension of sustainable development. This paper sets out to challenge these claims by a sustainability assessment in which the plantation is examined from a broader perspective, embedding it to the wider context of social and environmental problems in South Xinjiang. Methods comprise evapotranspiration calculations, interviews, a socioeconomic household survey, stakeholder dialogues, and literature research. Results affirm its economic sustainability, but see a mixed record for the social sphere. From the nature conservation point of view, it has to be classified as unsustainable because its high irrigation water consumption results in the downstream desiccation and desertification of natural riparian forests along the Tarim River, causing a forest loss in the downstream area twice the size of the forest gain in the upstream area. There is a trade-off between artificial shelterbelt plantations for urban ecosystem services on the one hand side, and natural riparian forests and their biodiversity on the other hand side. The paper recommends restricting agricultural extension, and using locally adapted less water consuming agroforestry schemes to protect urban dwellers from dust stress. Full article
(This article belongs to the Special Issue The Future of Water Management in Central Asia)
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Open AccessArticle Gas Exchanges and Stem Water Potential Define Stress Thresholds for Efficient Irrigation Management in Olive (Olea europea L.)
Water 2018, 10(3), 342; https://doi.org/10.3390/w10030342
Received: 4 February 2018 / Revised: 13 March 2018 / Accepted: 15 March 2018 / Published: 20 March 2018
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Abstract
With climate change and decreased water supplies, interest in irrigation scheduling based on plant water status is increasing. Stem water potential (ΨSWP) thresholds for irrigation scheduling in olive have been proposed, however, a physiologically-based evaluation of their reliability is needed. A
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With climate change and decreased water supplies, interest in irrigation scheduling based on plant water status is increasing. Stem water potential (ΨSWP) thresholds for irrigation scheduling in olive have been proposed, however, a physiologically-based evaluation of their reliability is needed. A large dataset collected at variable environmental conditions, growing systems, and genotypes was used to characterize the relation between ΨSWP and gas exchanges for olive. Based on the effect of drought stress on the ecophysiological parameters monitored, we described three levels of stress: no stress (ΨSWP above about −2 MPa), where the high variability of stomatal conductance (gs) suggests a tight stomatal control of water loss that limit ΨSWP drop, irrigation volumes applied to overcome this threshold had no effect on assimilation but reduced intrinsic water use efficiency (iWUE); moderate-stress (ΨSWP between about −2.0 and −3.5 MPa), where iWUE can be increased without damage to the photosynthetic apparatus of leaves; and high-stress (ΨSWP below about −3.5 MPa), where gs dropped below 150 mmol m−2 s−1 and the intercellular CO2 concentration increased proportionally, suggesting non-stomatal limitation to photosynthesis was operative. This study confirmed that olive ΨSWP should be maintained between −2 and −3.5 MPa for optimal irrigation efficiency and to avoid harmful water stress levels. Full article
(This article belongs to the Special Issue Advances in Agriculture Water Efficiency)
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Open AccessArticle Uncertainty Analysis of the Water Scarcity Footprint Based on the AWARE Model Considering Temporal Variations
Water 2018, 10(3), 341; https://doi.org/10.3390/w10030341
Received: 20 February 2018 / Revised: 11 March 2018 / Accepted: 17 March 2018 / Published: 19 March 2018
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Abstract
The purpose of this paper is to compare the degree of uncertainty of the water scarcity footprint using the Monte Carlo statistical method and block bootstrap method. Using the hydrological data of a water drainage basin in Korea, characterization factors based on the
[...] Read more.
The purpose of this paper is to compare the degree of uncertainty of the water scarcity footprint using the Monte Carlo statistical method and block bootstrap method. Using the hydrological data of a water drainage basin in Korea, characterization factors based on the available water remaining (AWARE) model were obtained. The uncertainties of the water scarcity footprint considering temporal variations in paddy rice production in Korea were estimated. The block bootstrap method gave five-times smaller percentage uncertainty values of the model output compared to that of the two different Monte Carlo statistical method scenarios. Incorrect estimation of the probability distribution of the AWARE characterization factor model is what causes the higher uncertainty in the water scarcity footprint value calculated by the Monte Carlo statistical method in this study. This is because AWARE characterization factor values partly follows discrete distribution with extreme value on one side. Therefore, this study suggests that the block bootstrap method is a better choice in analyzing uncertainty compared to the Monte Carlo statistical method when using the AWARE model to quantify the water scarcity footprint. Full article
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Open AccessArticle Real-Time Flood Control by Tree-Based Model Predictive Control Including Forecast Uncertainty: A Case Study Reservoir in Turkey
Water 2018, 10(3), 340; https://doi.org/10.3390/w10030340
Received: 18 December 2017 / Revised: 8 March 2018 / Accepted: 9 March 2018 / Published: 19 March 2018
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Abstract
Optimal control of reservoirs is a challenging task due to conflicting objectives, complex system structure, and uncertainties in the system. Real time control decisions suffer from streamflow forecast uncertainty. This study aims to use Probabilistic Streamflow Forecasts (PSFs) having a lead-time up to
[...] Read more.
Optimal control of reservoirs is a challenging task due to conflicting objectives, complex system structure, and uncertainties in the system. Real time control decisions suffer from streamflow forecast uncertainty. This study aims to use Probabilistic Streamflow Forecasts (PSFs) having a lead-time up to 48 h as input for the recurrent reservoir operation problem. A related technique for decision making is multi-stage stochastic optimization using scenario trees, referred to as Tree-based Model Predictive Control (TB-MPC). Deterministic Streamflow Forecasts (DSFs) are provided by applying random perturbations on perfect data. PSFs are synthetically generated from DSFs by a new approach which explicitly presents dynamic uncertainty evolution. We assessed different variables in the generation of stochasticity and compared the results using different scenarios. The developed real-time hourly flood control was applied to a test case which had limited reservoir storage and restricted downstream condition. According to hindcasting closed-loop experiment results, TB-MPC outperforms the deterministic counterpart in terms of decreased downstream flood risk according to different independent forecast scenarios. TB-MPC was also tested considering different number of tree branches, forecast horizons, and different inflow conditions. We conclude that using synthetic PSFs in TB-MPC can provide more robust solutions against forecast uncertainty by resolution of uncertainty in trees. Full article
(This article belongs to the Special Issue Adaptive Catchment Management and Reservoir Operation)
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Open AccessArticle Implementation of a Two-Source Model for Estimating the Spatial Variability of Olive Evapotranspiration Using Satellite Images and Ground-Based Climate Data
Water 2018, 10(3), 339; https://doi.org/10.3390/w10030339
Received: 6 November 2017 / Revised: 14 March 2018 / Accepted: 16 March 2018 / Published: 19 March 2018
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Abstract
A study was carried out to evaluate the potential use of the two-source Shuttleworth and Wallace (SW) model to compute the intra-orchard spatial variability of actual evapotranspiration (ET) of olive trees using satellite images and ground-based climate data. The study was conducted in
[...] Read more.
A study was carried out to evaluate the potential use of the two-source Shuttleworth and Wallace (SW) model to compute the intra-orchard spatial variability of actual evapotranspiration (ET) of olive trees using satellite images and ground-based climate data. The study was conducted in a drip-irrigated olive orchard using satellite images (Landsat 7 ETM+), which were acquired on clear sky days during the main phenological stages (2009/10 growing season). The performance of the SW model was evaluated using instantaneous latent heat flux (LE) measurements that were obtained from an eddy correlation system. At the time of satellite overpass, the estimated values of net radiation ( Rn i ) and soil heat flux ( G i ) were compared with ground measurements from a four-way net radiometer and soil heat flux plates, respectively. The results indicated that the SW model subestimated instantaneous LE (W m−2) and daily ET (mm d−1), with errors of 12% and 10% of observed values, respectively. The root mean square error (RMSE) and mean absolute error (MAE) values for instantaneous LE were 26 and 20 W m−2, while those for daily values of ET were 0.31 and 0.28 mm d−1, respectively. Finally, the submodels computed Rn i and G i with errors of between 4.0% and 8.0% of measured values and with RMSE and MAE between 25 and 39 W m−2. Full article
(This article belongs to the Special Issue Innovation Issues in Water, Agriculture and Food)
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Open AccessArticle Groundwater Chemistry Regulated by Hydrochemical Processes and Geological Structures: A Case Study in Tongchuan, China
Water 2018, 10(3), 338; https://doi.org/10.3390/w10030338
Received: 22 December 2017 / Revised: 14 March 2018 / Accepted: 14 March 2018 / Published: 19 March 2018
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Abstract
Knowledge of hydrochemical processes in groundwater helps to identify the relationship between geochemical processes and groundwater quality as well as to understand the hydrochemical evaluation of groundwater, which is important for the sustainable management of groundwater resources. This study aims to identify the
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Knowledge of hydrochemical processes in groundwater helps to identify the relationship between geochemical processes and groundwater quality as well as to understand the hydrochemical evaluation of groundwater, which is important for the sustainable management of groundwater resources. This study aims to identify the chemical characteristics of groundwater in the area of Tongchuan City, China. A total of 58 groundwater samples were collected. A hierarchical cluster analysis divided samples into three clusters and six sub-clusters (cluster 1a, 1b, 2a, 2b, 3a, 3b) according to hydrochemical facies. Graphical plots of multiple ionic ratios, saturation indices, and ion exchange indices were employed to examine hydrochemical processes that result in different hydrochemical facies of each cluster. Results show the predominance of carbonate and silicate weathering in cluster 1, silicate weathering in cluster 2, and carbonate weathering in cluster 3. Ionic exchange is a ubiquitous process among all clusters. The distribution of clusters is related to the regional geology, which may result in different hydrochemical processes. Two stratigraphic sections identify the differences in hydrochemical processes resulting from complex stratum structures and varied aquifer media. Cluster 2a shows an interesting difference in water chemistry along the groundwater flow path. Further study by oxygen and hydrogen isotope indicated that mixing between Quaternary and the Permian aquifers resulting from faulting is the main reason for the distinctive characteristic of cluster 2a. Full article
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Open AccessReview A Review of Permeable Pavement Clogging Investigations and Recommended Maintenance Regimes
Water 2018, 10(3), 337; https://doi.org/10.3390/w10030337
Received: 26 February 2018 / Revised: 14 March 2018 / Accepted: 14 March 2018 / Published: 17 March 2018
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Abstract
Understanding clogging mechanisms in permeable pavements can help optimize the required maintenance regime. In this review paper, methods for investigating clogging mechanisms are described. These include surface infiltration methods, the use of embedded sensors, and the development of modelling tools. Previously conducted surface
[...] Read more.
Understanding clogging mechanisms in permeable pavements can help optimize the required maintenance regime. In this review paper, methods for investigating clogging mechanisms are described. These include surface infiltration methods, the use of embedded sensors, and the development of modelling tools. Previously conducted surface infiltration tests indicate the importance of the age of a permeable pavement system and also local climatic conditions, including rainfall intensity. The results indicate that porous concrete generally has the highest infiltration capacity and this is followed by permeable interlocking concrete pavement and then porous asphalt. The measured infiltration rates decreased significantly even within two years of installation. There was an indirect relationship between surface infiltration rates and the age of the pavements. It was also found that the rainfall characteristics are important in selecting the type of pavement. Sensor technologies have been used mainly in the United States and there has been a reluctance to use such technologies in other parts of the world. Few studies have been conducted into modelling the changing performance of permeable pavement systems over time and there is a need to develop more general models. Various methods and machinery have been developed for cleaning and maintaining permeable pavements and there is no universally preferred approach currently available. Indeed, several of the commonly used maintenance methods have been shown to be relatively ineffective. Full article
(This article belongs to the Special Issue Permeable Pavements and Their Role in Sustainable Urban Development)
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Open AccessArticle Occurrence Probabilities of Wet and Dry Periods in Southern Italy through the SPI Evaluated on Synthetic Monthly Precipitation Series
Water 2018, 10(3), 336; https://doi.org/10.3390/w10030336
Received: 14 February 2018 / Revised: 9 March 2018 / Accepted: 14 March 2018 / Published: 17 March 2018
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Abstract
The present article investigates dry and wet periods in a large area of the Mediterranean basin. First, a stochastic model was applied to a homogeneous database of monthly precipitation values of 46 rain gauges in five regions of southern Italy. In particular, after
[...] Read more.
The present article investigates dry and wet periods in a large area of the Mediterranean basin. First, a stochastic model was applied to a homogeneous database of monthly precipitation values of 46 rain gauges in five regions of southern Italy. In particular, after estimating the model parameters, a set of 104 years of monthly precipitation for each rain gauge was generated by means of a Monte Carlo technique. Then, dry and wet periods were analyzed through the application of the standardized precipitation index (SPI) over 3-month and 6-month timespan (short-term) and 12-month and 24-month period (long-term). As a result of the SPI application on the generated monthly precipitation series, higher occurrence probabilities of dry conditions than wet conditions have been detected, especially when long-term precipitation scales are considered. Full article
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Open AccessArticle Land Use and Land Cover Changes (LULCC), a Key to Understand Soil Erosion Intensities in the Maritsa Basin
Water 2018, 10(3), 335; https://doi.org/10.3390/w10030335
Received: 30 December 2017 / Revised: 11 March 2018 / Accepted: 12 March 2018 / Published: 17 March 2018
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Abstract
Soil erosion is a major environmental and economic concern affecting all continents around the world. Soil loss facilitates land degradation, threatening both agricultural and natural environments in continental Europe. The overall objective of the present study is to reveal temporal changes of erosion
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Soil erosion is a major environmental and economic concern affecting all continents around the world. Soil loss facilitates land degradation, threatening both agricultural and natural environments in continental Europe. The overall objective of the present study is to reveal temporal changes of erosion risk in the Maritsa Basin, and also assess the temporal effects of land use and land cover changes (LULCC) on the gross erosion rate. The Revised Universal Soil Loss Equation (RUSLE) was utilized to monitor the distribution of the erosion risk zones and soil loss in the basin. The variables were either directly derived from the satellite imagery or computed using established equations or previous studies. The dynamic parameters were categorized into two-time frames as 1990 and 2015. The results indicate that the annual average erosion rate decreased from 0.895 to 0.828 t ha−1 year−1. This reduction is within the range of modeling error, potentially originated from input data uncertainties. The most extensive changes in the gross soil loss were found in both agricultural and artificial areas, which emphasize the significance of these two classes in soil erosion models. The research summarized here enhances understanding the impacts of land use and land cover (LULC) classes on erosion intensities. Full article
(This article belongs to the Special Issue Soil Erosion by Water)
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Open AccessArticle Comparison of Public Perception in Desert and Rainy Regions of Chile Regarding the Reuse of Treated Sewage Water
Water 2018, 10(3), 334; https://doi.org/10.3390/w10030334
Received: 2 February 2018 / Revised: 11 March 2018 / Accepted: 12 March 2018 / Published: 17 March 2018
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Abstract
The objective of this study was to compare the public perception in desert and rainy regions of Chile regarding the reuse of treated sewage water. The methodology of this study consisted of applying a survey to the communities of San Pedro de Atacama
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The objective of this study was to compare the public perception in desert and rainy regions of Chile regarding the reuse of treated sewage water. The methodology of this study consisted of applying a survey to the communities of San Pedro de Atacama (desert region) and Hualqui (rainy region) to identify attitudes about the reuse of sewage water. The survey was applied directly to men and women, 18 to 90 years old, who were living in the studied communities. The results indicate that inhabitants of San Pedro de Atacama (desert region) were aware of the state of their water resources, with 86% being aware that there are water shortages during some part of the year. In contrast, only 55% of residents in Hualqui (rainy region) were aware of water shortages. With respect of the reuse of treated sewage water, 47% of respondents in San Pedro de Atacama understood the concept, as compared to 27% in Hualqui. There was more acceptance of using treated sewage water for non-potable purposes than as drinking water. Full article
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Open AccessArticle Case Study on Water Quality Improvement in Xihu Lake through Diversion and Water Distribution
Water 2018, 10(3), 333; https://doi.org/10.3390/w10030333
Received: 25 January 2018 / Revised: 15 March 2018 / Accepted: 15 March 2018 / Published: 16 March 2018
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Abstract
Eutrophication in lakes and reservoirs is a serious environmental problem that has damaged ecosystem health worldwide. Water diversion is one of the most popular methods for improving the water quality in shallow lakes, as it dilutes pollutants in and diverts them out of
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Eutrophication in lakes and reservoirs is a serious environmental problem that has damaged ecosystem health worldwide. Water diversion is one of the most popular methods for improving the water quality in shallow lakes, as it dilutes pollutants in and diverts them out of the lake. However, simple diversion without rational water distribution cannot significantly enhance water exchange in the entire lake because dead water zones always exist. This paper illustrates a case study on water quality improvement in Xihu Lake by diversion and water distribution. Based on theoretical calculation, the diversion water discharge was determined and rationally distributed into four different locations. According to the field observations after the implementation of the diversion and water distribution project, the average velocity over the dead water zones increased approximately 50 times over that of prior to the project. The average water exchange period reduced from 68 days to 22.5 days. The average turbidity was 8.8% and 12.4% lower than before after two and four months of diversion, respectively. The maximum turbidity reduced from the original 27.5 NTU (Nephelometric Turbidity Unit) to 20.1 NTU after two months of diversion, then to 16.1 NTU after four months of diversion. It shows that this diversion and rational water distribution eliminates most of the dead water zones and achieves a favorable flow field, thus reducing the turbidity and increasing water transparency, which is conducive to the improvement of water quality. Full article
(This article belongs to the Special Issue Eutrophication Management: Monitoring and Control)
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Open AccessArticle Applicability of Constructed Wetlands for Water Quality Improvement in a Tea Estate Catchment: The Pussellawa Case Study
Water 2018, 10(3), 332; https://doi.org/10.3390/w10030332
Received: 16 February 2018 / Revised: 12 March 2018 / Accepted: 12 March 2018 / Published: 16 March 2018
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Abstract
Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrients and pesticides, and contamination from the human population working and residing therein. This study examined the quality of water in a drainage stream which runs through a congested network of
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Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrients and pesticides, and contamination from the human population working and residing therein. This study examined the quality of water in a drainage stream which runs through a congested network of ‘line houses’ (low-income housing, typically found arranged in straight ‘lines’ on estates) in the tea estate catchment area of Pussellawa in central Sri Lanka. The study evaluated the applicability of vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF) constructed wetlands for water polishing, as the residents use the stream water for various domestic purposes with no treatment other than possibly boiling. Water flow in the stream can vary significantly over time, and so investigations were conducted at various flow conditions to identify the hydraulic loading rate (HLR) bandwidth for wetland polishing applications. Two wetland models of 8 m × 1 m × 0.6 m (length × width × depth) were constructed and arranged as VSSF and HSSF units. Stream water was diverted to these units at HLRs of 3.3, 4, 5, 10, 20, and 40 cm/day. Results showed that both VSSF and HSSF wetland units were capable of substantially reducing five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), fecal coliform (FC), total coliform (TC), ammonia nitrogen (NH4+-N), and nitrate nitrogen (NO3-N) up to 20 cm/day HLR, with removal efficiencies of more than 64%, 60%, 90%, 93%, 70%, and 59% for BOD5, TSS, FC, TC, NH4+-N, and NO3-N, respectively, in the VSSF wetland unit; and more than 66%, 62%, 91%, 90%, 53%, and 77% for BOD5, TSS, FC, TC, NH4+-N, and NO3-N, respectively, in the HSSF wetland unit. Full article
(This article belongs to the Special Issue Wetlands for the Treatment of Agricultural Drainage Water)
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