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Water, Volume 10, Issue 10 (October 2018)

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Open AccessArticle Exploring the Statistical and Distributional Properties of Residential Water Demand at Fine Time Scales
Water 2018, 10(10), 1481; https://doi.org/10.3390/w10101481
Received: 30 August 2018 / Revised: 15 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
Residential water demand consists one of the most uncertain factors posing extra difficulties in the efficient planning and management of urban water systems. Currently, high resolution data from smart meters provide the means for a better understanding and modelling of this variable at
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Residential water demand consists one of the most uncertain factors posing extra difficulties in the efficient planning and management of urban water systems. Currently, high resolution data from smart meters provide the means for a better understanding and modelling of this variable at a household level and fine temporal scales. Having this in mind, this paper examines the statistical and distributional properties of residential water demand at a 15-minute and hourly scale, which are the temporal scales of interest for the majority of urban water modeling applications. Towards this, we investigate large residential water demand records of different characteristics. The analysis indicates that the studied characteristics of the marginal distribution of water demand vary among households as well as on the basis of different time intervals. Both month-to-month and hour-to-hour analysis reveal that the mean value and the probability of no demand exhibit high variability while the changes in the shape characteristics of the marginal distributions of the nonzero values are significantly less. The investigation of performance of 10 probabilistic models reveals that Gamma and Weibull distributions can be used to adequately describe the nonzero water demand records of different characteristics at both time scales. Full article
(This article belongs to the Special Issue Water Networks Management: New Perspectives)
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Open AccessArticle Hurricanes as a Major Driver of Coastal Erosion in the Mississippi River Delta: A Multi-Decadal Analysis of Shoreline Retreat Rates at Bay Champagne, Louisiana (USA)
Water 2018, 10(10), 1480; https://doi.org/10.3390/w10101480
Received: 24 September 2018 / Revised: 13 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
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Abstract
The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few
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The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years. Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessArticle Relationships Among Animal Communities, Lentic Habitats, and Channel Characteristics for Ecological Sediment Management
Water 2018, 10(10), 1479; https://doi.org/10.3390/w10101479
Received: 29 August 2018 / Revised: 15 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
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Abstract
This study used a multiscale analysis of relationships among the bitterling and mussel communities, lentic habitat structures with conditions and flooding frequency, and channel characteristics for application in ecological sediment management. From the Kizu River in Japan, 120 lentic habitats were sampled in
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This study used a multiscale analysis of relationships among the bitterling and mussel communities, lentic habitat structures with conditions and flooding frequency, and channel characteristics for application in ecological sediment management. From the Kizu River in Japan, 120 lentic habitats were sampled in 2007 and 2010. The floodplain vertical shape index (FVSI), which indicates the degree of convexity or concavity of the vertical shape of a floodplain, was used as channel characteristics using historical cross-section profiles obtained from 1960 to 2012. For examining the relationships between bitterlings/mussels and each habitat condition or structure, abundance values of bitterlings and mussels were transformed into habitat suitability index (HSI). Furthermore, the relationships between the number of habitat structures and FVSI were analyzed. The results indicated that bitterlings and mussels are more abundant in terrace ponds than in active ponds, especially so in terrace ponds located in the lower area of bars with a flooding frequency of 8–16 days/year (bitterlings), those located in the lower area of bars with a flooding frequency of 8 days/year, and those located in the upper area of bars with a flooding frequency of 16–22 days/year (mussels). These ponds tended to have less than 1 cm mud depth that was negatively related to abundance of mussels. These suitable habitat types tended to be located in channels with a floodplain vertical shape index between −0.35 and 0.05. We established countermeasures to prevent channel types with floodplain vertical shape index exceeding 0.05 instead of restoring the previous channel conditions. Full article
(This article belongs to the Special Issue Adaptive Catchment Management and Reservoir Operation)
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Open AccessArticle Numerical Investigation on the Hydraulic Properties of the Skimming Flow over Pooled Stepped Spillway
Water 2018, 10(10), 1478; https://doi.org/10.3390/w10101478
Received: 21 September 2018 / Revised: 4 October 2018 / Accepted: 15 October 2018 / Published: 19 October 2018
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Abstract
Pooled stepped spillway is known for high aeration efficiency and energy dissipation, but the understanding for the effects of pool weir configuration on the flow properties and energy loss is relatively limited, so RNG kε εturbulence model with VOF method was
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Pooled stepped spillway is known for high aeration efficiency and energy dissipation, but the understanding for the effects of pool weir configuration on the flow properties and energy loss is relatively limited, so RNG k ε εturbulence model with VOF method was employed to simulate the hydraulic characteristics of the stepped spillways with four types of pool weirs. The calculated results suggested the flow in the stepped spillway with staggered configuration of` two-sided pooled and central pooled steps (TP-CP) was highly three dimensional and created more flow instabilities and vortex structures, leading to 1.5 times higher energy dissipation rate than the fully pooled configuration (FP-FP). In FP-FP configuration, the stepped spillway with fully pooled and two-sided pooled steps (FP-TP) and the spillway with fully pooled and central pooled steps (FP-CP), the pressure on the horizontal step surfaces presented U-shaped variation, and TP-CP showed the greatest pressure fluctuation. For FP-TP and FP-CP, the vortex development in the transverse direction presented the opposite phenomenon, and the maximum vortex intensity in TP-CP occurred at Z/W = 0.25, while FP-FP illustrated no significant change in the transverse direction. The overlaying flow velocity distribution in the spanwise direction demonstrated no obvious difference among FP-FP, FP-TP, and FP-CP, while the velocity in TP-CP increased from the axial plane to the sidewalls, but the maximum velocity for all cases were approximately the same. Full article
(This article belongs to the Special Issue Advances in Hydraulics and Hydroinformatics)
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Open AccessArticle Stationary and Non-Stationary Frameworks for Extreme Rainfall Time Series in Southern Italy
Water 2018, 10(10), 1477; https://doi.org/10.3390/w10101477
Received: 16 August 2018 / Revised: 11 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
This study tests stationary and non-stationary approaches for modelling data series of hydro-meteorological variables. Specifically, the authors considered annual maximum rainfall accumulations observed in the Calabria region (southern Italy), and attention was focused on time series characterized by heavy rainfall events which occurred
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This study tests stationary and non-stationary approaches for modelling data series of hydro-meteorological variables. Specifically, the authors considered annual maximum rainfall accumulations observed in the Calabria region (southern Italy), and attention was focused on time series characterized by heavy rainfall events which occurred from 1 January 2000 in the study area. This choice is justified by the need to check if the recent rainfall events in the new century can be considered as very different or not from the events occurred in the past. In detail, the whole data set of each considered time series (characterized by a sample size N > 40 data) was analyzed, in order to compare recent and past rainfall accumulations, which occurred in a specific site. All the proposed models were based on the Two-Component Extreme Value (TCEV) probability distribution, which is frequently applied for annual maximum time series in Calabria. The authors discussed the possible sources of uncertainty related to each framework and remarked on the crucial role played by ergodicity. In fact, if the process is assumed to be non-stationary, then ergodicity cannot hold, and thus possible trends should be derived from external sources, different from the time series of interest: in this work, Regional Climate Models’ (RCMs) outputs were considered in order to assess possible trends of TCEV parameters. From the obtained results, it does not seem essential to adopt non-stationary models, as significant trends do not appear from the observed data, due to a relevant number of heavy events which also occurred in the central part of the last century. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle The Impact of River Discharge and Water Temperature on Manganese Release from the Riverbed during Riverbank Filtration: A Case Study from Dresden, Germany
Water 2018, 10(10), 1476; https://doi.org/10.3390/w10101476
Received: 19 July 2018 / Revised: 10 October 2018 / Accepted: 15 October 2018 / Published: 19 October 2018
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Abstract
The climate-related variables, river discharge, and water temperature, are the main factors controlling the quality of the bank filtrate by affecting infiltration rates, travel times, and redox conditions. The impact of temperature and discharge on manganese release from a riverbed were assessed by
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The climate-related variables, river discharge, and water temperature, are the main factors controlling the quality of the bank filtrate by affecting infiltration rates, travel times, and redox conditions. The impact of temperature and discharge on manganese release from a riverbed were assessed by water quality data from a monitoring transect at a riverbank filtration site in Dresden-Tolkewitz. Column experiments with riverbed material were used to assess the Mn release for four temperature and three discharge conditions, represented by varying infiltration rates. The observed Mn release was modeled as kinetic reactions via Monod-type rate formulations in PHREEQC. The temperature had a bigger impact than the infiltration rates on the Mn release. Infiltration rates of <0.3 m3/(m2·d) required temperatures >20 °C to trigger the Mn release. With increasing temperatures, the infiltration rates became less important. The modeled consumption rates of dissolved oxygen are in agreement with results from other bank filtration sites and are potentially suited for the further application of the given conditions. The determined Mn reduction rate constants were appropriate to simulate Mn release from the riverbed sediments but seemed not to be suited for simulations in which Mn reduction is likely to occur within the aquifer. Sequential extractions revealed a decrease of easily reducible Mn up to 25%, which was found to reflect the natural stratification within the riverbed, rather than a depletion of the Mn reservoir. Full article
(This article belongs to the Special Issue Efficiency of Bank Filtration and Post-Treatment)
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Open AccessFeature PaperArticle Discovering the Political Implications of Coproduction in Water Governance
Water 2018, 10(10), 1475; https://doi.org/10.3390/w10101475
Received: 17 August 2018 / Revised: 14 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
This paper asks what lessons can be learned from experiences with coproduction in water governance. For this, we review a comprehensive corpus of articles in the field of water governance that relies on the term. We find that there are radically different understandings
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This paper asks what lessons can be learned from experiences with coproduction in water governance. For this, we review a comprehensive corpus of articles in the field of water governance that relies on the term. We find that there are radically different understandings of what coproduction means in different branches of the water governance literature. Through this review, we demonstrate how and why coproduction needs to be analyzed for its political implications. Despite being timely and pressing, these questions are not addressed in a sufficient way by the scholarly debate on coproduction. In order to fill this knowledge gap, we first distinguish different historical traditions of coproduction and then explore their political implications along three questions: The “why?”, the “who?”, and the “how?”. We show that these questions find different answers not just between but also within different traditions of using the term. After describing and contrasting these variants, we conclude by summarizing the main lessons from our review and by identifying questions which call for future research. Full article
Open AccessArticle Water Protection Zoning as an Instrument of Preservation for Lake Baikal
Water 2018, 10(10), 1474; https://doi.org/10.3390/w10101474
Received: 29 August 2018 / Revised: 15 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
The article is dedicated to the justification and practical implementation of a nature protection-based methodological approach to define the boundaries of the Lake Baikal protection zone and form proposals related to the harmonization of instruments of environmentally responsible development of the territory, which
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The article is dedicated to the justification and practical implementation of a nature protection-based methodological approach to define the boundaries of the Lake Baikal protection zone and form proposals related to the harmonization of instruments of environmentally responsible development of the territory, which has the status of a World Heritage site as it contains 20% of the world’s fresh water supply. An analysis of the contemporary conditions of Lake Baikal and its surrounding landscapes show environmental degradation of the area. The most important aspects in solving the existing problem may be the construction of a science-based definition of the Lake Baikal water protection zone and compliance with the universal global values related to the requirements of ecological threat prevention. The main landscape-hydrological design principles for the water protection zone are studied in this article. A method for the functional water protection zoning of urban territories is also given. This has been implemented in Baikalsk town, which is located on the Baikal shore and is considered to be one of the most environmentally damaged territories. Proposals include recommendations on the harmonization of the landscape-hydrological principles of territory assessment and methods for target landscape planning; the setting of various restrictions within the boundaries of existing industrial and settlement zones; the creation of an overall system of environmental health monitoring for Lake Baikal and its protection zones; and for ensuring interactions with the public. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessArticle Characteristics of Positive Surges in a Rectangular Channel
Water 2018, 10(10), 1473; https://doi.org/10.3390/w10101473
Received: 17 September 2018 / Revised: 9 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
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Abstract
A positive surge is an unsteady open channel flow motion characterized by an increase of flow depth. In previous experimental studies, a positive surge was typically induced by either a sudden increase of discharge in a channel or by the rapid closure of
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A positive surge is an unsteady open channel flow motion characterized by an increase of flow depth. In previous experimental studies, a positive surge was typically induced by either a sudden increase of discharge in a channel or by the rapid closure of a downstream sluice gate, thus leading to a steep initial profile. However, in many instances, the evolution of a positive surge is of a progressive manner (e.g., in the downstream navigation canal during the emptying operation of lock chambers). In the present work, the inception and development of a positive surge induced by a progressive increase of discharge was investigated in a rectangular channel with a smooth bed. Both undular and breaking surges were studied. The results demonstrate that the maximum wave height at the first wave crest of an undular surge is in very close agreement with the McCowan theory. Additionally, the wave amplitude essentially shows a linearly increasing trend with an increasing surge Froude number up to Fr0 = 1.26 to 1.28, whereas it tends to suggest a power law reduction for larger surge Froude numbers. Moreover, the dispersion of undular surges is consistent with the linear wave theory only for surge Froude numbers close to unity. Overall, the present study demonstrates the unique features of positive surges induced by a progressive increase of discharge. Full article
(This article belongs to the Section Hydraulics)
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Open AccessArticle Gender and Community Mainstreaming in Fog Water Collection Systems
Water 2018, 10(10), 1472; https://doi.org/10.3390/w10101472
Received: 17 August 2018 / Revised: 26 September 2018 / Accepted: 11 October 2018 / Published: 19 October 2018
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Abstract
Fog water collection is an emerging opportunity to combat local water shortages in water-scarce areas where sustainable access to water is unreliable, but fog events are frequent. Since fog water systems are implemented within or near communities, they eliminate or decrease the need
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Fog water collection is an emerging opportunity to combat local water shortages in water-scarce areas where sustainable access to water is unreliable, but fog events are frequent. Since fog water systems are implemented within or near communities, they eliminate or decrease the need to travel far distances for the collection of water during times of scarcity. As a result, these systems decrease the physical and social burden of water collection on women and girls, who are the primary water gatherers in most traditional communities. This is an important outcome because women and girls are disproportionately affected by water scarcity and are not seen as equals in water management, access, or control. This paper illustrates how several fog water collection projects have shown, empirically, that the positive outcomes for women and girls may include the freeing of time for domestic and educational pursuits, improved health outcomes, and improved perceptions of self and others’ perceptions of women. These findings are important at a time when the world at large is addressing the Sustainable Development Agenda, where Sustainable Development Goal (SDG) 6 necessitates safe water and sanitation for all and SDG 5 ensures gender equality to empower all women and girls. Full article
(This article belongs to the Section Water Use and Scarcity)
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Open AccessArticle Daily Water Quality Forecast of the South-To-North Water Diversion Project of China Based on the Cuckoo Search-Back Propagation Neural Network
Water 2018, 10(10), 1471; https://doi.org/10.3390/w10101471
Received: 21 September 2018 / Revised: 13 October 2018 / Accepted: 15 October 2018 / Published: 18 October 2018
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Abstract
Water quality forecast is a critical part of water security management. Spatiotemporal and multifactorial variations make water quality very complex and changeable. In this article, a novel model, which was based on back propagation neural network that was optimized by the Cuckoo Search
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Water quality forecast is a critical part of water security management. Spatiotemporal and multifactorial variations make water quality very complex and changeable. In this article, a novel model, which was based on back propagation neural network that was optimized by the Cuckoo Search algorithm (hereafter CS-BP model), was applied to forecast daily water quality of the Middle Route of South-to-North Water Diversion Project of China. Nine water quality indicators, including conductivity, chlorophyll content, dissolved oxygen, dissolved organic matter, pH, permanganate index, turbidity, total nitrogen, and water temperature were the predictand. Seven external environmental factors, including air temperature, five particulate matter (PM2.5), rainfall, sunshine duration, water flow, wind velocity, and water vapor pressure were the default predictors. A data pre-processing method was applied to select pertinent predictors. The results show that the CS-BP model has the best forecast accuracy, with the Mean Absolute Percentage Errors (MAPE) of 0.004%–0.33%, and the lowest Root Mean Square Error (RMSE) of each water quality indicator in comparison with traditional Back Propagation (BP) model, General Regression Neural Network model and Particle Swarm Optimization-Back Propagation model under default data proportion, 150:38 (training data: testing data). When training data reduced from 150 to 140, and from 140 to 130, the CS-BP model still produced the best forecasts, with the MAPEs of 0.014%–0.057% and 0.004%–1.154%, respectively. The results show that the CS-BP model can be an effective tool in daily water quality forecast with limited observed data. The improvement of the Cuckoo Search algorithm such as calculation speed, the forecast errors reduction of the CS-BP model, and the large-scale impacts such as land management on different water quality indicators, will be the focus of future research. Full article
(This article belongs to the Section Water Quality and Ecosystems)
Open AccessArticle Analysis of Flood Risk of Urban Agglomeration Polders Using Multivariate Copula
Water 2018, 10(10), 1470; https://doi.org/10.3390/w10101470
Received: 13 September 2018 / Revised: 3 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
Urban agglomeration polders (UAPs) are often used to control flooding in eastern China. The impacts of UAPs on individual flood events have been extensively examined, but how flood risks are influenced by UAPs is much less examined. This study aimed to explore a
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Urban agglomeration polders (UAPs) are often used to control flooding in eastern China. The impacts of UAPs on individual flood events have been extensively examined, but how flood risks are influenced by UAPs is much less examined. This study aimed to explore a three-dimensional joint distribution of annual flood volume, peak flow and water level to examine UAPs’ impact on flood risks based on hydrological simulations. The dependence between pairwise hydrological characteristics are measured by rank correlation coefficients and graphs. An Archimedean Copula is applied to model the dependence structure. This approach is applied to the Qinhuai River Basin where UAPs are used proactively for flood control. The result shows that the Frank Copula can better represent the dependence structure in the Qinhuai River Basin. UAPs increase risks of individual flood characteristics and integrated risks. UAPs have a relatively greater impact on water level than the other two flood characteristics. It is noted that the impact on flood risk levels off for greater floods. Full article
(This article belongs to the Special Issue Flood Modelling: Regional Flood Estimation and GIS Based Techniques)
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Open AccessArticle Effect of Climate Change on Soil Erosion in a Mountainous Mediterranean Catchment (Central Pindus, Greece)
Water 2018, 10(10), 1469; https://doi.org/10.3390/w10101469
Received: 24 September 2018 / Revised: 16 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
The aim of this study was to assess soil erosion changes in the mountainous catchment of the Portaikos torrent (Central Greece) under climate change. To this end, precipitation and temperature data were derived from a high-resolution (25 × 25 km) RegCM3 regional climate
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The aim of this study was to assess soil erosion changes in the mountainous catchment of the Portaikos torrent (Central Greece) under climate change. To this end, precipitation and temperature data were derived from a high-resolution (25 × 25 km) RegCM3 regional climate model for the baseline period 1974–2000 and future period 2074–2100. Additionally, three GIS layers were generated regarding land cover, geology, and slopes in the study area, whereas erosion state was recognized after field observations. Subsequently, the erosion potential model (EPM) was applied to quantify the effects of precipitation and temperature changes on soil erosion. The results showed a decrease (−21.2%) in annual precipitation (mm) and increase (+3.6 °C) in mean annual temperature until the end of the 21st century, and the above changes are likely to lead to a small decrease (−4.9%) in soil erosion potential. Full article
(This article belongs to the Special Issue Erosion and Torrent Control)
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Open AccessArticle Evaluation of Rainfall Temporal Distribution Models with Annual Maximum Rainfall Events in Seoul, Korea
Water 2018, 10(10), 1468; https://doi.org/10.3390/w10101468
Received: 17 September 2018 / Revised: 14 October 2018 / Accepted: 14 October 2018 / Published: 17 October 2018
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Abstract
This study evaluated five models of rainfall temporal distribution (i.e., the Yen and Chow model, Mononobe model, alternating block method, Huff model, and Keifer and Chu model), with the annual maximum rainfall events selected from Seoul, Korea, from 1961 to 2016. Three different
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This study evaluated five models of rainfall temporal distribution (i.e., the Yen and Chow model, Mononobe model, alternating block method, Huff model, and Keifer and Chu model), with the annual maximum rainfall events selected from Seoul, Korea, from 1961 to 2016. Three different evaluation measures were considered: the absolute difference between the rainfall peaks of the model and the observed, the root mean square error, and the pattern correlation coefficient. Also, sensitivity analysis was conducted to determine whether the model, or the randomness of the rainfall temporal distribution, had the dominant effect on the runoff peak flow. As a result, the Keifer and Chu model was found to produce the most similar rainfall peak to the observed, the root mean square error was smaller for the Yen and Chow model and the alternating block method, and the pattern correlation was larger for the alternating block method. Overall, the best model to approximate the annual maximum rainfall events observed in Seoul, Korea, was found to be the alternating block method. Finally, the sensitivity of the runoff peak flow to the model of rainfall temporal distribution was found to be much higher than that to the randomness of the rainfall temporal distribution. In particular, in small basins with a high curve number (CN) value, the sensitivity of the runoff peak flow to the randomness of the rainfall temporal distribution was found to be insignificant. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle Optimized Water and Fertilizer Management of Mature Jujube in Xinjiang Arid Area Using Drip Irrigation
Water 2018, 10(10), 1467; https://doi.org/10.3390/w10101467
Received: 7 September 2018 / Revised: 12 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
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Abstract
Studying water–fertilizer coupling effects in a drip irrigation system is critical for sustainable agricultural development in arid areas, such as that of Xinjiang in China, to find out the optimized water and fertilizer management. Therefore, a two-year field experiment was conducted to find
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Studying water–fertilizer coupling effects in a drip irrigation system is critical for sustainable agricultural development in arid areas, such as that of Xinjiang in China, to find out the optimized water and fertilizer management. Therefore, a two-year field experiment was conducted to find out how the combination of three levels of irrigation quotas and three levels of fertilizer amounts would affect the physiological and growth indexes of jujube, as well as ascertain the differences between drip irrigation and flood irrigation. The results showed that the interacted and coupled effects of irrigation and fertilization influenced most of the physiological indicators and growth indexes. On the other hand, the physiological and growth indexes were increased after transferring flood irrigation to drip irrigation, as the maximum chlorophyll content (CC) and photosynthetic nitrogen use efficiency (PNUE) values increased on average by 6.00%, and 11.39% in 2016, and 1.47% and 6.83% in 2017, respectively. Undoubtedly, inappropriate water and fertilizer management had negative impacts on jujube growth and yield. Based on the treatments and results in this paper, low fertilizer and moderate irrigation would be the best choice. The crop yield, irrigation water use efficiency (iWUE), and fertilizer partial productivity (PFP) increased by 6.77%, 29.48%, and 193.62% in 2016, and similar increments were also found in 2017 of 6.17%, 78.72%, and 133.06%, respectively. This indicated that fertilizer efficiency was promoted along with water use, and in turn, the water amounts were adjusted by the amount of fertilizer that was applied. Based on a comprehensive consideration of the physiological and growth indexes, a mathematical model was established, and the optimized irrigation and fertilizer amounts of jujube in northern Xinjiang area were found to be 815 mm and 400 kg ha−1 (with N–P2O5–K2O proportioned at 2–1–1.5). The results that were obtained in this paper would provide theoretical reference to the sustainable development of jujube plantation using drip irrigation in the arid areas. Full article
(This article belongs to the Special Issue Data-Driven Methods for Agricultural Water Management)
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Open AccessReview Woody Plant Encroachment Impacts on Groundwater Recharge: A Review
Water 2018, 10(10), 1466; https://doi.org/10.3390/w10101466
Received: 1 September 2018 / Revised: 14 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
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Abstract
Woody plant encroachment has profound impacts on the sustainable management of water resources in water-limited ecosystems. However, our understanding of the effects of this global phenomenon on groundwater recharge at local and regional scales is limited. Here, we reviewed studies related to (i)
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Woody plant encroachment has profound impacts on the sustainable management of water resources in water-limited ecosystems. However, our understanding of the effects of this global phenomenon on groundwater recharge at local and regional scales is limited. Here, we reviewed studies related to (i) recharge estimation methods; (ii) mechanisms by which woody plants impact groundwater recharge; (iii) impacts of woody plant on recharge across different soil and geology; (iv) hydrological repercussions of woody plant removal; and (v) research gaps and needs for groundwater studies. We identified six different methods: water balance, water table, isotopes, chloride mass balance, electrical geophysical imaging, and modeling were used to study the impact of woody encroachment on groundwater. Woody plant encroachment could alter soil infiltration rates, soil water storage, transpiration, interception, and subsurface pathways to affect groundwater recharge. The impact is highly variable, with the extent and the magnitude varying across the soil, substrate, plant cover, and topographic locations. Our review revealed mixed effects of woody plant removal on groundwater recharge. Studies of litter interception, root water uptake, soil moisture dynamics, and deep percolation along with the progression of woody plant encroachment are still limited, warranting further experimental studies focusing on groundwater recharge. Overall, information about woody plant encroachment impacts on groundwater resources across a range of scales is essential for long-range planning of water resources. Full article
(This article belongs to the Special Issue Ecohydrology of Woodlands and Savannas)
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Open AccessArticle Contrasting Responses among Aquatic Organism Groups to Changes in Geomorphic Complexity Along a Gradient of Stream Habitat Restoration: Implications for Restoration Planning and Assessment
Water 2018, 10(10), 1465; https://doi.org/10.3390/w10101465
Received: 27 August 2018 / Revised: 28 September 2018 / Accepted: 6 October 2018 / Published: 17 October 2018
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Abstract
Many stream restoration projects aim to increase geomorphic complexity, assuming that this increases habitat heterogeneity and, thus, biodiversity. However, empirical data supporting these linkages remain scant. Previous assessments of stream restoration suffer from incomplete quantification of habitat complexity, or a narrow focus on
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Many stream restoration projects aim to increase geomorphic complexity, assuming that this increases habitat heterogeneity and, thus, biodiversity. However, empirical data supporting these linkages remain scant. Previous assessments of stream restoration suffer from incomplete quantification of habitat complexity, or a narrow focus on only one organism group and/or one restoration measure, limiting learning. Based on a comprehensive quantification of geomorphic complexity in 20 stream reaches in northern Sweden, ranging from streams channelized for timber floating to restored and reference reaches, we investigated responses of macroinvertebrates, diatoms, and macrophytes to multiple geomorphic metrics. Sediment size heterogeneity, which was generally improved in restored sites, favored macroinvertebrate and diatom diversity and macroinvertebrate abundance. In contrast, macrophyte diversity responded to increased variation along the longitudinal stream profile (e.g., step-pools), which was not consistently improved by the restoration. Our analyses highlight the value of learning across multiple restoration projects, both in identifying which aspects of restoration have succeeded, and pinpointing other measures that might be targeted during adaptive management or future restoration. Given our results, a combination of restoration measures targeting not only sediment size heterogeneity, but also features such as step-pools and instream wood, is most likely to benefit benthic biota in streams. Full article
(This article belongs to the Special Issue Restoration of Biodiversity in Streams and Rivers)
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Open AccessFeature PaperArticle Optimal Energy Recovery from Water Distribution Systems Using Smart Operation Scheduling
Water 2018, 10(10), 1464; https://doi.org/10.3390/w10101464
Received: 21 August 2018 / Revised: 13 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
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Abstract
Micro hydropower generators (micro turbines), are used to recover excess energy from hydraulic systems and these applications have important potential in renewable energy production. One of the most viable environments for the use of micro turbines is the water distribution network where, by
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Micro hydropower generators (micro turbines), are used to recover excess energy from hydraulic systems and these applications have important potential in renewable energy production. One of the most viable environments for the use of micro turbines is the water distribution network where, by design, there is always excess energy since minimum pressures are to be maintained throughout the system, and the system is designed to meet future water supply needs of a planning period. Under these circumstances, maintaining the target pressures is not an easy task due to the increasing complexity of the water distribution network to supply future demands. As a result, pressures at several locations of the network tend to be higher than the required minimum pressures. In this paper, we outline a methodology to recover this excess energy using smart operation management and the best placement of micro turbines in the system. In this approach, the best micro turbine locations and their operation schedule is determined to recover as much available excess energy as possible from the water distribution network while satisfying the current demand for water supply and pressure. Genetic algorithms (GAs) are used to obtain optimal solutions and a “smart seeding” approach is developed to improve the performance of the GA. The Dover Township pump-driven water distribution system in New Jersey, United States of America (USA) was selected as the study area to test the proposed methodology. This pump-driven network was also converted into a hypothetical gravity-driven network to observe the differences between the energy recovery potential of the pump-driven and gravity-driven systems. The performance of the energy recovery system was evaluated by calculating the equivalent number of average American homes that can be fed by the energy produced and the resulting carbon-dioxide emission reductions that may be achieved. The results show that this approach is an effective tool for applications in renewable energy production in water distribution systems for small towns such as Dover Township. It is expected that, for larger water distribution systems with high energy usage, the energy recovery potential will be much higher. Full article
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Open AccessArticle Spatiotemporal Variation of Snowfall to Precipitation Ratio and Its Implication on Water Resources by a Regional Climate Model over Xinjiang, China
Water 2018, 10(10), 1463; https://doi.org/10.3390/w10101463
Received: 13 September 2018 / Revised: 4 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
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Abstract
Snow contributes one of the main water sources to runoff in the arid region of China. A clear understanding of the spatiotemporal variation of snowfall is not only required for climate change assessment, but also plays a critical role in water resources management.
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Snow contributes one of the main water sources to runoff in the arid region of China. A clear understanding of the spatiotemporal variation of snowfall is not only required for climate change assessment, but also plays a critical role in water resources management. However, in-situ observations or gridded datasets hardly meet the requirement and cannot provide precise spatiotemporal details on snowfall across the region. This study attempted to apply the Weather Research and Forecasting (WRF) model to clarify the spatiotemporal variation of snowfall and the ratio of snowfall to total precipitation over Xinjiang in China during the 1979–2015 period. The results showed that the snowfall increased in the southern edge of the Tarim Basin, the Ili Valley, and the Altay Mountains, but decreased in the Tianshan Mountains and the Kunlun Mountains. The snowfall/precipitation (S/P) ratio revealed the opposite trends in low-elevation regions and mountains in the study area. The S/P ratio rose in the Tarim Basin and the Junggar Basin, but declined in the Altay Mountains, the Tianshan Mountains, and the west edge of the Junggar Basin. The study area comprises two major rivers in the middle of the Tianshan Mountains. Both the runoff magnitude increase and earlier occurrence of snowmelt recharge in runoff identified for the 1980s were compared with the 2000s level in decreasing S/P ratio regions. Full article
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Open AccessArticle Synthesis of Self-Gravity Settling Faceted-Anatase TiO2 with Dominant {010} Facets for the Photocatalytic Degradation of Acetaminophen and Study of the Type of Generated Oxygen Vacancy in Faceted-TiO2
Water 2018, 10(10), 1462; https://doi.org/10.3390/w10101462
Received: 13 September 2018 / Revised: 10 October 2018 / Accepted: 13 October 2018 / Published: 17 October 2018
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Abstract
In this study, faceted TiO2, predominately exposed with {010} facets (T-{010}), was synthesized with a two-step hydrothermal reaction and used for the degradation of acetaminophen (ACE) in an aqueous solution. T-{010} showed considerable photocatalytic reactivity, and its easy-settling (gravity-settling, ~97% of
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In this study, faceted TiO2, predominately exposed with {010} facets (T-{010}), was synthesized with a two-step hydrothermal reaction and used for the degradation of acetaminophen (ACE) in an aqueous solution. T-{010} showed considerable photocatalytic reactivity, and its easy-settling (gravity-settling, ~97% of T-{010} settled after 30 min) property demonstrated acceptable reusability. A solid-state chemical reduction approach (NaBH4) at a mild temperature (300 °C) was used for generation of an oxygen vacancy in T-{010} and P25 (commercial TiO2). The oxygen vacancy concentrations of the samples were investigated by electron paramagnetic resonance (EPR). It was also found that NaBH4 reduction induced the generation of both surface and subsurface Ti3+ on colored P25, but only surface Ti3+ species were formed on colored T-{010}. The prepared colored TiO2 samples were successfully used for photocatalytic degradation of ACE in an aqueous solution under visible light illumination. Full article
(This article belongs to the Section Water and Wastewater Treatment)
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Open AccessArticle Communication Optimization for Multiphase Flow Solver in the Library of OpenFOAM
Water 2018, 10(10), 1461; https://doi.org/10.3390/w10101461
Received: 29 September 2018 / Revised: 12 October 2018 / Accepted: 12 October 2018 / Published: 16 October 2018
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Abstract
Multiphase flow solvers are widely-used applications in OpenFOAM, whose scalability suffers from the costly communication overhead. Therefore, we establish communication-optimized multiphase flow solvers in OpenFOAM. In this paper, we first deliver a scalability bottleneck test on the typical multiphase flow case damBreak and
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Multiphase flow solvers are widely-used applications in OpenFOAM, whose scalability suffers from the costly communication overhead. Therefore, we establish communication-optimized multiphase flow solvers in OpenFOAM. In this paper, we first deliver a scalability bottleneck test on the typical multiphase flow case damBreak and reveal that the Message Passing Interface (MPI) communication in a Multidimensional Universal Limiter for Explicit Solution (MULES) and a Preconditioned Conjugate Gradient (PCG) algorithm is the short slab of multiphase flow solvers. Furthermore, an analysis of the communication behavior is carried out. We find that the redundant communication in MULES and the global synchronization in PCG are the performance limiting factors. Based on the analysis, we propose our communication optimization algorithm. For MULES, we remove the redundant communication and obtain optMULES. For PCG, we import several intermediate variables and rearrange PCG to reduce the global communication. We also overlap the computation of matrix-vector multiply and vector update with the non-blocking computation. The resulting algorithms are respectively referred to as OFPiPePCG and OFRePiPePCG. Extensive experiments show that our proposed method could dramatically increase the parallel scalability and solving speed of multiphase flow solvers in OpenFOAM approximately without the loss of accuracy. Full article
(This article belongs to the Section Hydraulics)
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Open AccessArticle Evaluation of Decentralized, Closely-Spaced Precipitation Water and Treated Wastewater Infiltration
Water 2018, 10(10), 1460; https://doi.org/10.3390/w10101460
Received: 26 September 2018 / Revised: 11 October 2018 / Accepted: 13 October 2018 / Published: 16 October 2018
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Abstract
Decentralized water management requires innovative technical solutions due to restricted operational and economic resources. In this study, a combined, decentralized infiltration system in the form of closely-spaced sub-systems for precipitation water and treated wastewater has been numerically analyzed. Flow and transport simulation shows
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Decentralized water management requires innovative technical solutions due to restricted operational and economic resources. In this study, a combined, decentralized infiltration system in the form of closely-spaced sub-systems for precipitation water and treated wastewater has been numerically analyzed. Flow and transport simulation shows that a closely-spaced system, by arranging the infiltration pipes closely in a longitudinal manner, is feasible under the consideration of German national guidelines for both infiltration methods. Precipitation events up to a recurrence interval of five years can be infiltrated alongside with treated wastewater of a one-family house without significant reduction of the wastewaters’ residence time. Scenario analyses highlight that harmless wastewater infiltration remains mainly undisturbed for a broad bandwidth of hydrological, subsurface, and technical conditions. Full article
(This article belongs to the Section Water and Wastewater Treatment)
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Open AccessArticle An Accelerated Tool for Flood Modelling Based on Iber
Water 2018, 10(10), 1459; https://doi.org/10.3390/w10101459
Received: 27 September 2018 / Revised: 11 October 2018 / Accepted: 14 October 2018 / Published: 16 October 2018
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Abstract
This paper presents Iber+, a new parallel code based on the numerical model Iber for two-dimensional (2D) flood inundation modelling. The new implementation, which is coded in C++ and takes advantage of the parallelization functionalities both on CPUs (central processing units) and GPUs
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This paper presents Iber+, a new parallel code based on the numerical model Iber for two-dimensional (2D) flood inundation modelling. The new implementation, which is coded in C++ and takes advantage of the parallelization functionalities both on CPUs (central processing units) and GPUs (graphics processing units), was validated using different benchmark cases and compared, in terms of numerical output and computational efficiency, with other well-known hydraulic software packages. Depending on the complexity of the specific test case, the new parallel implementation can achieve speedups up to two orders of magnitude when compared with the standard version. The speedup is especially remarkable for the GPU parallelization that uses Nvidia CUDA (compute unified device architecture). The efficiency is as good as the one provided by some of the most popular hydraulic models. We also present the application of Iber+ to model an extreme flash flood that took place in the Spanish Pyrenees in October 2012. The new implementation was used to simulate 24 h of real time in roughly eight minutes of computing time, while the standard version needed more than 15 h. This huge improvement in computational efficiency opens up the possibility of using the code for real-time forecasting of flood events in early-warning systems, in order to help decision making under hazardous events that need a fast intervention to deploy countermeasures. Full article
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Open AccessArticle A Multi-GCM Assessment of the Climate Change Impact on the Hydrology and Hydropower Potential of a Semi-Arid Basin (A Case Study of the Dez Dam Basin, Iran)
Water 2018, 10(10), 1458; https://doi.org/10.3390/w10101458
Received: 28 August 2018 / Revised: 8 October 2018 / Accepted: 8 October 2018 / Published: 16 October 2018
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Abstract
In this paper, the impact of climate change on the climate and discharge of the Dez Dam Basin and the hydropower potential of two hydropower plants (Bakhtiari and Dez) is investigated based on the downscaled outputs of six GCMs (General Circulation Models) and
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In this paper, the impact of climate change on the climate and discharge of the Dez Dam Basin and the hydropower potential of two hydropower plants (Bakhtiari and Dez) is investigated based on the downscaled outputs of six GCMs (General Circulation Models) and three SRES (Special Report on Emission Scenarios) scenarios for the early, mid and late 21st century. Projections of all the scenarios and GCMs revealed a significant rise in temperature (up to 4.9 °C) and slight to moderate variation in precipitation (up to 18%). Outputs of the HBV hydrologic model, enforced by projected datasets, show a reduction of the annual flow by 33% under the climate change condition. Further, analyzing the induced changes in the inflow and hydropower generation potential of the Bakhtiari and Dez dams showed that both inflow and hydropower generation is significantly affected by climate change. For the Bakhtiari dam, this indicates a consistent reduction of inflow (up to 27%) and electricity generation (up to 32%). While, in the Dez dam case, the inflow is projected to decrease (up to 22%) and the corresponding hydropower is expected to slightly increase (up to 3%). This contrasting result for the Dez dam is assessed based on its reservoir and hydropower plant capacity, as well as other factors such as the timely releases to meet different demands and flow regime changes under climate change. The results show that the Bakhtiari reservoir and power plant will not meet the design-capacity outputs under the climate change condition as its large capacity cannot be fully utilized; while there is room for the further development of the Dez power plant. Comparing the results of the applied GCMs showed high discrepancies among the outputs of different models. Full article
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Open AccessArticle Removal of Natural Organic Matter and Organic Micropollutants during Riverbank Filtration in Krajkowo, Poland
Water 2018, 10(10), 1457; https://doi.org/10.3390/w10101457
Received: 19 September 2018 / Revised: 4 October 2018 / Accepted: 11 October 2018 / Published: 16 October 2018
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Abstract
The aim of this article is to evaluate the removal of natural organic matter and micropollutants at a riverbank filtration site in Krajkowo, Poland, and its dependence on the distance between the wells and the river and related travel times. A high reduction
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The aim of this article is to evaluate the removal of natural organic matter and micropollutants at a riverbank filtration site in Krajkowo, Poland, and its dependence on the distance between the wells and the river and related travel times. A high reduction in dissolved organic carbon (40–42%), chemical oxygen demand (65–70%), and colour (42–47%) was found in the riverbank filtration wells at a distance of 60–80 m from the river. A lower reduction in dissolved organic carbon (26%), chemical oxygen demand (42%), and colour (33%) was observed in a horizontal well. At greater distances of the wells from the river, the removal of pharmaceutical residues and pesticides was in the range of 52–66% and 55–66%, respectively. The highest removal of pharmaceutical residues and pesticides was found in a well located 250 m from the river and no micropollutants were detected in a well located 680 m from the river. The results provide evidence of the high efficacy of riverbank filtration for contaminant removal. Full article
(This article belongs to the Special Issue Efficiency of Bank Filtration and Post-Treatment)
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Open AccessArticle Historical Trends of Academic Research on the Water Environment in Japan: Evidence from the Academic Literature in the Past 50 Years
Water 2018, 10(10), 1456; https://doi.org/10.3390/w10101456
Received: 21 September 2018 / Revised: 11 October 2018 / Accepted: 13 October 2018 / Published: 16 October 2018
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Abstract
This paper analyzes historical trends of academic research on the water environment in Japan over the past 50 years in relation to societal circumstances by looking into 1470 articles published in a Japanese domestic journal during 1961–2010. We examined three components of the
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This paper analyzes historical trends of academic research on the water environment in Japan over the past 50 years in relation to societal circumstances by looking into 1470 articles published in a Japanese domestic journal during 1961–2010. We examined three components of the individual articles to substantiate the trends including “Visions”, “Target Water”, and “Objects”. The database of these components was first constructed, and then statistically analyzed. Principal components analyses revealed two historical turning points of the research trends, in 1970 and in the mid-1990s, showing first a clear transition of the main concern from industrial pollution to eutrophication, and later, a transition to global environmental issues. We also demonstrate that Visions and Target Water gradually diversified during the past 50 years, indicating that although the research activity in the early periods focused on serious pollution issues, more recently, the scope of water environmental studies expanded to various other issues along with the improvement in the quality of the water environment. We argue that academic research activity in Japan was conducted in close association with public concern and global movements in a timely and sensitive manner. Such knowledge could also provide implications to other nations facing serious water pollution. Full article
(This article belongs to the Section Water Resources Management and Governance)
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Open AccessRetraction Retraction: Liu, L., et al. Evaluation of Water Resource Security Based on an MIV-BP Model in a Karst Area. Water 2018, 10, 786
Water 2018, 10(10), 1454; https://doi.org/10.3390/w10101454
Received: 27 September 2018 / Accepted: 27 September 2018 / Published: 16 October 2018
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Abstract
The Water Editorial Office has been made aware that the published paper [1] has a significant overlap with a previously published manuscript from the same authors, submitted to a Chinese journal.[...] Full article
(This article belongs to the Section Water Use and Scarcity)
Open AccessArticle Migration of Gyrotactic Micro-Organisms in Water
Water 2018, 10(10), 1455; https://doi.org/10.3390/w10101455
Received: 30 August 2018 / Revised: 9 October 2018 / Accepted: 12 October 2018 / Published: 15 October 2018
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Abstract
Understanding the swimming characteristics of micro-organisms is significant for modelling the migration of motile cells and corresponding ecological risk assessments associated with harmful algae in oceans and estuaries. Presented in this paper is an experimental and numerical investigation of swimming characteristics of a
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Understanding the swimming characteristics of micro-organisms is significant for modelling the migration of motile cells and corresponding ecological risk assessments associated with harmful algae in oceans and estuaries. Presented in this paper is an experimental and numerical investigation of swimming characteristics of a typical gyrotactic micro-organism, Heterosigma akashiwo (H. akashiwo) in water, based on the technology of planar laser-induced fluorescence and the finite volume method. Two-dimensional swimming velocity of algal cells are obtained by analyzing cells’ trajectories in the vertical plane, and three-dimensional swimming velocity is reconstructed based on the assumption that cells’ swimming is isotropic in the horizontal plane. Four important parameters are given to reflect the swimming characteristics of gyrotactic cells in still water, including the mean swimming speed (Vs = 146 μm/s), the relative strength of reorientation by gravitational torque to rotational diffusion (λ = 1.96), the time scale of reorientation (B = 5.6 s), and rotational diffusivity (Dr = 0.046 rad2/s). A database of the ambient vorticity, mean swimming velocity and diffusivity tensor is established, by solving Fokker-Planck equation for the probability density function of cells’ swimming under the combined action of gravity, rotational diffusion, and the ambient vorticity. The mean swimming velocity and translational diffusion tensor of H. akashiwo are found to change with the horizontal and vertical vorticity. It is also shown that gyrotactic cells swim in a given direction for a weak horizontal vorticity, in contrast to cells’ tumbling and being trapped for a strong horizontal vorticity. Full article
(This article belongs to the Section Water Quality and Ecosystems)
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Open AccessArticle The Construction and Comparison of Regional Drought Severity-Duration-Frequency Curves in Two Colombian River Basins—Study of the Sumapaz and Lebrija Basins
Water 2018, 10(10), 1453; https://doi.org/10.3390/w10101453
Received: 27 August 2018 / Revised: 15 September 2018 / Accepted: 18 September 2018 / Published: 15 October 2018
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Abstract
Accurate classification of drought-severity is one of the most challenging issues in designing regional monitoring and control plans, especially in developing countries, where resources are scarce and must be carefully optimized to maximize social benefit. Typically, drought assessment is performed using drought indices
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Accurate classification of drought-severity is one of the most challenging issues in designing regional monitoring and control plans, especially in developing countries, where resources are scarce and must be carefully optimized to maximize social benefit. Typically, drought assessment is performed using drought indices which enable the interpretation of complex climatic information series for operational purposes. Frequency analyses are also useful for estimating future occurrence probabilities, even on regional scales. This study generated regional Severity-Duration-Frequency (SDF) curves for two Colombian catchments (Sumapaz and Lebrija River Basins), and 7 index-calculation procedures. First, the relationships between the two catchments were analyzed to obtain differences between drought indices. Second, the consistency among the indices that identified the same drought types for each region was evaluated. Finally, historical regional drought occurrences were selected, characterized, and located in local SDF curves to determine their gravity. It was concluded that (i) curves for the same indices displayed similar behavior, when comparing the two case studies; (ii) a certain degree of consistency existed in regional curves, which identify the same drought types (meteorological and agricultural droughts being the most coherent); (iii) meteorological drought regional events, identified through different drought-indices methodologies, were the most common for both case studies, followed by agricultural droughts and hydrological droughts; (iv) when analyzing occurrences with higher return periods, there is coherence when using different methodologies; and (v) identified historical events, which are located on larger return period zones of SDF curves (around 10, 25, and 50 years), had large impacts on regional socio-economic issues. Hence, it was possible to confirm that regional SDF curves could become potentially useful tools for the prioritization of drought-vulnerable zones. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle Least Squares Support Vector Mechanics to Predict the Stability Number of Rubble-Mound Breakwaters
Water 2018, 10(10), 1452; https://doi.org/10.3390/w10101452
Received: 31 August 2018 / Revised: 11 October 2018 / Accepted: 11 October 2018 / Published: 15 October 2018
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Abstract
In coastal engineering, empirical formulas grounded on experimental works regarding the stability of breakwaters have been developed. In recent years, soft computing tools such as artificial neural networks and fuzzy models have started to be employed to diminish the time and cost spent
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In coastal engineering, empirical formulas grounded on experimental works regarding the stability of breakwaters have been developed. In recent years, soft computing tools such as artificial neural networks and fuzzy models have started to be employed to diminish the time and cost spent in these mentioned experimental works. To predict the stability number of rubble-mound breakwaters, the least squares version of support vector machines (LSSVM) method is used because it can be assessed as an alternative one to diverse soft computing techniques. The LSSVM models have been operated through the selected seven parameters, which are determined by Mallows’ Cp approach, that are, namely, breakwater permeability, damage level, wave number, slope angle, water depth, significant wave heights in front of the structure, and peak wave period. The performances of the LSSVM models have shown superior accuracy (correlation coefficients (CC) of 0.997) than that of artificial neural networks (ANN), fuzzy logic (FL), and genetic programming (GP), that are all implemented in the related literature. As a result, it is thought that this study will provide a practical way for readers to estimate the stability number of rubble-mound breakwaters with more accuracy. Full article
(This article belongs to the Special Issue Machine Learning Applied to Hydraulic and Hydrological Modelling)
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