Water

15 pages, 1205 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Farmer Cooperation in Participatory Irrigation in South Asia: Insights from Game Theory

by Simon Hone, Lin Crase, Michael Burton, Bethany Cooper, Vasant P. Gandhi, Muhammad Ashfaq, Bakhshal Lashari and Bashir Ahmad

Water 2020, 12(5), 1329; https://doi.org/10.3390/w12051329 - 8 May 2020

Cited by 8 | Viewed by 3692

Abstract

Participatory irrigation, where farmers are given greater control and management responsibility, has been a topic of controversy for many years. Initially seen as a panacea for dealing with weaknesses in state-run irrigation, participatory irrigation has generated mixed results, especially in South Asia. Part [...] Read more.

Participatory irrigation, where farmers are given greater control and management responsibility, has been a topic of controversy for many years. Initially seen as a panacea for dealing with weaknesses in state-run irrigation, participatory irrigation has generated mixed results, especially in South Asia. Part of the challenge of understanding the conditions that promote and undermine participatory irrigation is that it is seldom deployed in the same way. For example, irrigation fees collected by farmers are not handled in the same manner, even within a single country. In some instances, a large portion of collected monies is retained locally and in others, only a small portion is kept for local use. In this paper, we use game theory to contemplate how the portion of irrigation fees retained locally might impact on the effectiveness of participatory irrigation. We show that there are multiple plausible equilibria, and that allowing farmers to retain more funds locally might shift behaviour from an uncooperative equilibrium to a cooperative outcome. However, we also find that it is unlikely for there to be a singular fix and we use empirical evidence to demonstrate the conundrums of making participatory irrigation sustainable. Full article

(This article belongs to the Special Issue Using Applied Economics to Study Participatory Irrigation Institutions and their Impact in South Asia)

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22 pages, 5196 KiB

Open AccessEditor’s ChoiceArticle

Zonation of Positively Buoyant Jets Interacting with the Water-Free Surface Quantified by Physical and Numerical Modelling

by Javier García-Alba, Javier F. Bárcena and Andrés García

Water 2020, 12(5), 1324; https://doi.org/10.3390/w12051324 - 7 May 2020

Cited by 7 | Viewed by 3215

Abstract

The evolution of positively buoyant jets was studied with non-intrusive techniques—Particle Image Velocimetry (PIV) and Laser Induce Fluorescence (LIF)—by analyzing four physical tests in their four characteristic zones: momentum dominant zone (jet-like), momentum to buoyancy transition zone (jet to plume), buoyancy dominant zone [...] Read more.

The evolution of positively buoyant jets was studied with non-intrusive techniques—Particle Image Velocimetry (PIV) and Laser Induce Fluorescence (LIF)—by analyzing four physical tests in their four characteristic zones: momentum dominant zone (jet-like), momentum to buoyancy transition zone (jet to plume), buoyancy dominant zone (plume-like), and lateral dispersion dominant zone. Four configurations were tested modifying the momentum and the buoyancy of the effluent through variations of flow discharge and the thermal gradient with the receiving water body, respectively. The physical model results were used to evaluate the performance of numerical models to describe such flows. Furthermore, a new method to delimitate the four characteristic zones of positively buoyant jets interacting with the water-free surface was proposed using the angle (α) shaped by the tangent of the centerline trajectory and the longitudinal axis. Physical model results showed that the dispersion of mass (concentrations) was always greater than the dispersion of energy (velocity) during the evolution of positively buoyant jets. The semiempirical models (CORJET and VISJET) underestimated the trajectory and overestimated the dilution of positively buoyant jets close to the impact zone with the water-free surface. The computational fluid dynamics (CFD) model (Open Field Operation And Manipulation model (OpenFOAM)) is able to reproduce the behavior of positively buoyant jets for all the proposed zones according to the physical results. Full article

(This article belongs to the Special Issue Physical Modelling in Hydraulics Engineering)

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20 pages, 51257 KiB

Open AccessEditor’s ChoiceArticle

Detecting Patterns of Changes in River Water Temperature in Poland

by Renata Graf and Dariusz Wrzesiński

Water 2020, 12(5), 1327; https://doi.org/10.3390/w12051327 - 7 May 2020

Cited by 29 | Viewed by 4254

Abstract

The study determined water temperature trends of rivers in Poland in the period 1971–2015, and also their spatial and temporal patterns. The analysis covered daily water temperature of 53 rivers recorded at 94 water gauge stations and air temperature at 43 meteorological stations. [...] Read more.

The study determined water temperature trends of rivers in Poland in the period 1971–2015, and also their spatial and temporal patterns. The analysis covered daily water temperature of 53 rivers recorded at 94 water gauge stations and air temperature at 43 meteorological stations. Average monthly, annual, seasonal and maximum annual tendencies of temperature change were calculated using the Mann–Kendall (M–K) test. Regional patterns of water temperature change were determined on the basis of Ward’s hierarchical grouping for 16 correlation coefficients of average annual water temperature in successive 30-year sub-periods of the multi-annual period of 1971–2015. Moreover, regularities in monthly temperature trends in the annual cycle were identified using 12 monthly values obtained from the M–K Z test. The majority of average annual air and water temperature series demonstrate statistically significant positive trends. In three seasons: spring, summer and autumn, upward tendencies of temperature were detected at 70%–90% of the investigated water gauges. In 82% of the analysed rivers, similarity to the tendencies of change of monthly air temperature was concluded, with the climatic factor being recognised as of decisive importance for the changes in water thermal characteristics of the majority of rivers in Poland. In the winter months, positive trends of temperature were considerably weaker and in general statistically insignificant. On a regional scale, rivers with a quasi-natural thermal regime experienced temperature increases from April to November. In the other cases, different directions of change in river water temperature (RWT) were attributed to various forms of human impact. It was also found that for the majority of rivers the average annual water temperature in the analysed 30-year sub-periods displayed upward trends, statistically significant or close to the significance threshold. Stronger trends were observed in the periods after 1980, while a different nature of water temperature change was detected only in a couple of mountainous rivers or rivers transformed by human impact. In the beginning of the analysed period (1971–2015), the average annual water temperature of these rivers displayed positive and statistically significant trends, while after 1980 the trends were negative. The detected regularities and spatial patterns of water temperature change in rivers with a quasi-natural regime revealed a strong influence of climate on the modification of their thermal regime features. Rivers characterised by a clearly different nature of temperature change, both in terms of the direction of the tendencies observed and their statistical significance, were distinguished by alterations of water thermal characteristics caused by human activity. The results obtained may be useful in optimising the management of aquatic ecosystems, for which water temperature is a significant indicator of the ongoing environmental changes. Full article

(This article belongs to the Special Issue Climate Change and Human Impact on Freshwater Water Resources: Rivers and Lakes)

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34 pages, 4781 KiB

Open AccessEditor’s ChoiceArticle

Developing a Risk-Based Consensus-Based Decision-Support System Model for Selection of the Desirable Urban Water Strategy: Kashafroud Watershed Study

by Reza Javidi Sabbaghian and A. Pouyan Nejadhashemi

Water 2020, 12(5), 1305; https://doi.org/10.3390/w12051305 - 5 May 2020

Cited by 3 | Viewed by 3148

Abstract

In recent years, complexities related to a variety of sustainable development criteria and several preferences of stakeholders have caused a serious challenge for selecting the more desirable urban water strategy within watershed. In addition, stakeholders might have several risk attitudes depending on the [...] Read more.

In recent years, complexities related to a variety of sustainable development criteria and several preferences of stakeholders have caused a serious challenge for selecting the more desirable urban water strategy within watershed. In addition, stakeholders might have several risk attitudes depending on the number of criteria satisfied by water strategies. Accordingly, a risk-based consensus-based group decision-support system model is proposed for choosing the more desirable water strategy, using the external modified ordered weighted averaging (EMOWA) and internal modified ordered weighted averaging (IMOWA) operators. The operators calculate the scores of strategies in several risk-taking attitudes of group decision-making, considering the sustainable development criteria. Additionally, the consensus-seeking phase is considered using a risk-based weighted Minkowski’s method. This model is successfully implemented for the Kashafroud urban watershed in Iran, for selecting the more desirable urban water strategy in 2040. Accordingly, in the completely risk-averse viewpoint, the stakeholders select the combined supply-demand management strategy satisfying all of the criteria. In contrast, in the completely risk-prone standpoint, the stakeholders choose the demand management strategy satisfying at least one criterion. Developing the risk-based consensus-based group decision-support system model is suggested for integrated urban watershed management for selecting the more desirable strategy, satisfying the sustainable development criteria. Full article

(This article belongs to the Special Issue Application of the Systems Approach to the Management of Complex Water Systems)

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21 pages, 14497 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Snowmelt Estimation Techniques for Enhanced Spring Peak Flow Prediction

by Jetal Agnihotri and Paulin Coulibaly

Water 2020, 12(5), 1290; https://doi.org/10.3390/w12051290 - 1 May 2020

Cited by 7 | Viewed by 4493

Abstract

Water resources management and planning requires accurate and reliable spring flood forecasts. In cold and snowy countries, particularly in snow-dominated watersheds, enhanced flood prediction requires adequate snowmelt estimation techniques. Whereas the majority of the studies on snow modeling have focused on comparing the [...] Read more.

Water resources management and planning requires accurate and reliable spring flood forecasts. In cold and snowy countries, particularly in snow-dominated watersheds, enhanced flood prediction requires adequate snowmelt estimation techniques. Whereas the majority of the studies on snow modeling have focused on comparing the performance of empirical techniques and physically based methods, very few studies have investigated empirical models and conceptual models for improving spring peak flow prediction. The objective of this study is to investigate the potential of empirical degree-day method (DDM) to effectively and accurately predict peak flows compared to sophisticated and conceptual SNOW-17 model at two watersheds in Canada: the La-Grande River Basin (LGRB) and the Upper Assiniboine river at Shellmouth Reservoir (UASR). Additional insightful contributions include the evaluation of a seasonal model calibration approach, an annual model calibration method, and two hydrological models: McMaster University Hydrologiska Byrans Vattenbalansavdelning (MAC-HBV) and Sacramento Soil Moisture Accounting model (SAC-SMA). A total of eight model scenarios were considered for each watershed. Results indicate that DDM was very competitive with SNOW-17 at both the study sites, whereas it showed significant improvement in prediction accuracy at UASR. Moreover, the seasonally calibrated model appears to be an effective alternative to an annual model calibration approach, while the SAC-SMA model outperformed the MAC-HBV model, no matter which snowmelt computation method, calibration approach, or study basin is used. Conclusively, the DDM and seasonal model calibration approach coupled with the SAC-SMA hydrologic model appears to be a robust model combination for spring peak flow estimation. Full article

(This article belongs to the Section Hydrology)

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50 pages, 11228 KiB

Open AccessEditor’s ChoiceReview

Irrigation of World Agricultural Lands: Evolution through the Millennia

by Andreas N. Angelakιs, Daniele Zaccaria, Jens Krasilnikoff, Miquel Salgot, Mohamed Bazza, Paolo Roccaro, Blanca Jimenez, Arun Kumar, Wang Yinghua, Alper Baba, Jessica Anne Harrison, Andrea Garduno-Jimenez and Elias Fereres

Water 2020, 12(5), 1285; https://doi.org/10.3390/w12051285 - 1 May 2020

Cited by 63 | Viewed by 25692

Abstract

Many agricultural production areas worldwide are characterized by high variability of water supply conditions, or simply lack of water, creating a dependence on irrigation since Neolithic times. The aim of this paper is to provide an overview of the evolution of irrigation of [...] Read more.

Many agricultural production areas worldwide are characterized by high variability of water supply conditions, or simply lack of water, creating a dependence on irrigation since Neolithic times. The aim of this paper is to provide an overview of the evolution of irrigation of agricultural lands worldwide, based on bibliographical research focusing on ancient water management techniques and ingenious irrigation practices and their associated land management practices. In ancient Egypt, regular flooding by the Nile River meant that early agriculture probably consisted of planting seeds in soils that had been recently covered and fertilized with floodwater and silt deposits. On the other hand, in arid and semi-arid regions farmers made use of perennial springs and seasonal runoff under circumstances altogether different from the river civilizations of Mesopotamia, Egypt, India, and early dynasties in China. We review irrigation practices in all major irrigation regions through the centuries. Emphasis is given to the Bronze Age civilizations (Minoans, Egyptians, and Indus valley), pre-Columbian, civilizations from the historic times (e.g., Chinese, Hellenic, and Roman), late-Columbians (e.g., Aztecs and Incas) and Byzantines, as well as to Ottomans and Arabs. The implications and impacts of irrigation techniques on modern management of water resources, as well as on irrigated agriculture, are also considered and discussed. Finally, some current major agricultural water management challenges are outlined, concluding that ancient practices could be adapted to cope with present challenges in irrigated agriculture for increasing productivity and sustainability. Full article

(This article belongs to the Special Issue Water Supply and Water Scarcity)

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12 pages, 490 KiB

Open AccessEditor’s ChoiceReview

Responsible Water Reuse Needs an Interdisciplinary Approach to Balance Risks and Benefits

by Milou M. L. Dingemans, Patrick W. M. H. Smeets, Gertjan Medema, Jos Frijns, Klaasjan J. Raat, Annemarie P. van Wezel and Ruud P. Bartholomeus

Water 2020, 12(5), 1264; https://doi.org/10.3390/w12051264 - 29 Apr 2020

Cited by 25 | Viewed by 7417

Abstract

Freshwater is a precious resource, and shortages can lead to water stress, impacting agriculture, industry, and other sectors. Wastewater reuse is increasingly considered as an opportunity to meet the freshwater demand. Legislative frameworks are under development to support the responsible reuse of wastewater, [...] Read more.

Freshwater is a precious resource, and shortages can lead to water stress, impacting agriculture, industry, and other sectors. Wastewater reuse is increasingly considered as an opportunity to meet the freshwater demand. Legislative frameworks are under development to support the responsible reuse of wastewater, i.e., to balance benefits and risks. In an evaluation of the proposed European regulation for water reuse, we concluded that the proposed regulation is not practically feasible, as the water provider alone is responsible for the risk assessment and management, even beyond their span of control. The required knowledge and resources are extensive. Therefore, without clear guidance for implementation, the regulation would hinder implementation of reuse programs. As a consequence, the current practice of uncontrolled, unintentional, and indirect reuse continues, including related risks and inefficiency. Therefore, we provide an outline of the interdisciplinary approach required to design and achieve safe, responsible water reuse. Responsible water reuse requires knowledge of water demand and availability, quality and health, technology, and governance for the various types of application. Through this paper we want to provide a starting point for an interdisciplinary agenda to compile and generate knowledge (databases), approaches, guidelines, case examples, codes of practice, and legislation to help bring responsible water reuse into practice. Full article

(This article belongs to the Special Issue Water Security and Governance in Catchments)

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13 pages, 3763 KiB

Open AccessEditor’s ChoiceArticle

Escherichia coli Antimicrobial Resistance Variability in Water Runoff and Soil from a Remnant Native Prairie, an Improved Pasture, and a Cultivated Agricultural Watershed

by Maitreyee Mukherjee, Terry Gentry, Heidi Mjelde, John P. Brooks, Daren Harmel, Lucas Gregory and Kevin Wagner

Water 2020, 12(5), 1251; https://doi.org/10.3390/w12051251 - 28 Apr 2020

Cited by 6 | Viewed by 4173

Abstract

Although many previous studies have examined patterns of antimicrobial resistance (AMR) and multidrug resistance (MDR) from domestic animals and farm environments, comparatively little is known about the environmental sources and natural reservoirs of AMR and MDR. In this study, we collected stormwater runoff [...] Read more.

Although many previous studies have examined patterns of antimicrobial resistance (AMR) and multidrug resistance (MDR) from domestic animals and farm environments, comparatively little is known about the environmental sources and natural reservoirs of AMR and MDR. In this study, we collected stormwater runoff and soil samples from three watersheds in Texas. Escherichia coli (E. coli) were enumerated, isolated, and analyzed for resistance patterns. E. coli from all sites, irrespective of land use, displayed the presence of AMR/MDR. Higher levels of AMR/MDR were observed in water compared to soil. More isolates were resistant to cephalothin than other antibiotics. For water isolates, 94% was resistant to cephalothin, 27% to tetracycline, and 15% to ampicillin. Across all sites, a large percentage of water isolates demonstrated MDR with 34% resistant to ≥2 antibiotics and 11% to ≥3 antibiotics. All AMR soil isolates were resistant to cephalothin (87% of the total soil isolates), but only 8.9% were MDR. High cephalothin resistance observed in both soil and water suggests the presence of native, cephalothin-resistant E. coli. Higher MDR observed within water compared to the soil populations suggests that resistance sources other than soil, such as more recent fecal depositions as opposed to residual AMR in soil, could have contributed to higher antibiotic-resistant E. coli in runoff. Full article

(This article belongs to the Section Water Quality and Contamination)

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18 pages, 5338 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Risk and Resilience: A Case of Perception versus Reality in Flood Management

by Nirupama Agrawal, Mark Elliott and Slobodan P Simonovic

Water 2020, 12(5), 1254; https://doi.org/10.3390/w12051254 - 28 Apr 2020

Cited by 17 | Viewed by 6032

Abstract

Canada’s vast regions are reacting to climate change in uncertain ways. Understanding of local disaster risks and knowledge of underlying causes for negative impacts of disasters are critical factors to working toward a resilient environment across the social, economic, and the built sectors. [...] Read more.

Canada’s vast regions are reacting to climate change in uncertain ways. Understanding of local disaster risks and knowledge of underlying causes for negative impacts of disasters are critical factors to working toward a resilient environment across the social, economic, and the built sectors. Historically, floods have caused more economical and social damage around the world than other types of natural hazards. Since the 1900s, the most frequent hazards in Canada have been floods, wildfire, drought, and extreme cold, in terms of economic damage. The recent flood events in the Canadian provinces of Ontario, New Brunswick, Quebec, Alberta, and Manitoba have raised compelling concerns. These include should communities be educated with useful knowledge on hazard risk and resilience so they would be interested in the discussion on the vital role they can play in building resilience in their communities. Increasing awareness that perceived risk can be very different from the real threat is the motivation behind this study. The main objectives of this study include identifying and quantifying the gap between people’s perception of exposure and susceptibility to the risk and a lack of coping capacity and objective assessment of risk and resilience, as well as estimating an integrated measure of disaster resilience in a community. The proposed method has been applied to floods as an example, using actual data on the geomorphology of the study area, including terrain and low lying regions. It is hoped that the study will encourage a broader debate if a unified strategy for disaster resilience would be feasible and beneficial in Canada. Full article

(This article belongs to the Special Issue Application of the Systems Approach to the Management of Complex Water Systems)

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31 pages, 8094 KiB

Open AccessEditor’s ChoiceArticle

Web-Based Tool for the Development of Intensity Duration Frequency Curves under Changing Climate at Gauged and Ungauged Locations

by Andre Schardong, Slobodan P. Simonovic, Abhishek Gaur and Dan Sandink

Water 2020, 12(5), 1243; https://doi.org/10.3390/w12051243 - 27 Apr 2020

Cited by 25 | Viewed by 5692

Abstract

Rainfall Intensity–Duration–Frequency (IDF) curves are among the most essential datasets used in water resources management across the globe. Traditionally, they are derived from observations of historical rainfall, under the assumption of stationarity. Change of climatic conditions makes use of historical data for development [...] Read more.

Rainfall Intensity–Duration–Frequency (IDF) curves are among the most essential datasets used in water resources management across the globe. Traditionally, they are derived from observations of historical rainfall, under the assumption of stationarity. Change of climatic conditions makes use of historical data for development of IDFs for the future unreliable, and in some cases, may lead to underestimated infrastructure designs. The IDF_CC tool is designed to assist water professionals and engineers in producing IDF estimates under changing climatic conditions. The latest version of the tool (Version 4) provides updated IDF curve estimates for gauged locations (rainfall monitoring stations) and ungauged sites using a new gridded dataset of IDF curves for the land mass of Canada. The tool has been developed using web-based technologies and takes the form of a decision support system (DSS). The main modifications and improvements between version 1 and the latest version of the IDF_CC tool include: (i) introduction of the Generalized Extreme value (GEV) distribution; (ii) updated equidistant matching algorithm (QM); (iii) gridded IDF curves dataset for ungauged location and (iv) updated Climate Models. Full article

(This article belongs to the Special Issue Extreme Value Analysis of Short-Duration Rainfall and Intensity–Duration–Frequency Models)

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22 pages, 5869 KiB

Open AccessEditor’s ChoiceArticle

Variability of Trends in Precipitation across the Amazon River Basin Determined from the CHIRPS Precipitation Product and from Station Records

by Victor Hugo da Motta Paca, Gonzalo E. Espinoza-Dávalos, Daniel Medeiros Moreira and Georges Comair

Water 2020, 12(5), 1244; https://doi.org/10.3390/w12051244 - 27 Apr 2020

Cited by 57 | Viewed by 10256

Abstract

The Amazon River Basin is the largest rainforest in the world. Long-term changes in precipitation trends in the basin can affect the continental water balance and the world’s climate. The precipitation trends in the basin are not spatially uniform; estimating these trends only [...] Read more.

The Amazon River Basin is the largest rainforest in the world. Long-term changes in precipitation trends in the basin can affect the continental water balance and the world’s climate. The precipitation trends in the basin are not spatially uniform; estimating these trends only at locations where station data are available has an inherent bias. In the present research, the spatially distributed annual precipitation trends were studied in the Amazon River Basin from the year 1981 to 2017 using the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) product. The precipitation trends were also cross-validated at locations where station data were available. The research also identifies clusters within the basin where trends showed a larger increase (nine clusters) or decrease in precipitation (10 clusters). The overall precipitation trend in the Amazon River Basin over 37 years showed a 2.8 mm/year increase, with a maximum of 45.1 mm/year and minimum of −37.9 mm/year. The highest positive cluster was in Cuzco in the Ucayali River basin, and the lowest negative was in Santa Cruz de la Sierra, in the upstream Madeira River basin. The total volume of the incoming precipitation was 340,885.1 km³, with a withdrawal of −244,337.1 km³. Cross-validation was performed using 98 in situ stations with more than 20 years of recorded data, obtaining an R² of 0.981, a slope of 1.027, and a root mean square error (RMSE) of 363.6 mm/year. The homogeneous, standardized, and continuous long-term time series provided by CHIRPS is a valuable product for basins with a low-density network of stations such as the Amazon Basin. Full article

(This article belongs to the Section Hydrology)

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14 pages, 5761 KiB

Open AccessEditor’s ChoiceArticle

Response of LUCC on Runoff Generation Process in Middle Yellow River Basin: The Gushanchuan Basin

by Caihong Hu, Li Zhang, Qiang Wu, Shan-e-hyder Soomro and Shengqi Jian

Water 2020, 12(5), 1237; https://doi.org/10.3390/w12051237 - 26 Apr 2020

Cited by 33 | Viewed by 3924

Abstract

Runoff reduction in most river basins in China has become a hotpot in recent years. The Gushanchuan river, a primary tributary of the middle Yellow river, Northern China, showed a significant downward trend in the last century. Little is known regarding the relative [...] Read more.

Runoff reduction in most river basins in China has become a hotpot in recent years. The Gushanchuan river, a primary tributary of the middle Yellow river, Northern China, showed a significant downward trend in the last century. Little is known regarding the relative contributions of changing environment to the observed hydrological trends and response on the runoff generation process in its watershed. On the basis of observed hydrological and meteorological data from 1965–2010, the Mann-Kendall trend test and climate elasticity method were used to distinguish the effects of climate change and human activities on runoff in the Gushanchuan basin. The results indicate that the runoff in the Gushanchuan Basin has experienced significant declines as large as 77% from 1965 to 2010, and a mutation point occurred around 1997; the contribution rate of climate change to runoff change is 12.9–15.1%, and the contribution rate of human activities to runoff change is 84.9–87.1%. Then we divided long-term data sequence into two stages around the mutation point, and analyzed runoff generation mechanisms based on land use and cover changes (LUCC). We found that the floods in the Gushanchuan Basin were still dominated by Excess-infiltration runoff, but the proportion in 1965–1997 and 1998–2010 decreased gradually (68.46% and 45.83% in turn). The proportion of Excess-storage runoff and Mixed runoff has increased, which means that the runoff is made up of more runoff components. The variation law of the LUCC indicates that the forest area increased by 49.61%, the confluence time increased by 50.42%, and the water storage capacity of the watershed increased by 30.35%. Full article

(This article belongs to the Special Issue Hydrologic, Hydraulic and Geomorphic Modeling for Small and Ungauged Basins)

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22 pages, 346 KiB

Open AccessEditor’s ChoiceArticle

The Wicked Problem the Water Framework Directive Cannot Solve. The Governance Approach in Dealing with Pollution of Nutrients in Surface Water in the Netherlands, Flanders, Lower Saxony, Denmark and Ireland

by Mark Wiering, Duncan Liefferink, Daan Boezeman, Maria Kaufmann, Ann Crabbé and Nanda Kurstjens

Water 2020, 12(5), 1240; https://doi.org/10.3390/w12051240 - 26 Apr 2020

Cited by 32 | Viewed by 5999

Abstract

The Water Framework Directive (WFD) is typically a framework directive that tries to encourage integration of policies for water quality and agriculture. Nutrients (nitrates, phosphates) from agricultural sources remain a ‘wicked problem’ in realizing the aims of the WFD, partly because the directive [...] Read more.

The Water Framework Directive (WFD) is typically a framework directive that tries to encourage integration of policies for water quality and agriculture. Nutrients (nitrates, phosphates) from agricultural sources remain a ‘wicked problem’ in realizing the aims of the WFD, partly because the directive has to rely on other, neighboring policies to tackle to problem pressure of nutrients; it seems to lack instruments and measures to directly intervene in relevant agricultural policies. This contribution describes the different governance approaches of five member states and regions (The Netherlands, Flanders in Belgium, Lower Saxony- in Germany, Denmark and Ireland) to the nutrients problem and specifically focuses on the relationship between the nature of governance and the nature of measures taken. On the one hand, countries can vary in terms of a more consensual or antagonistic approach to dealing with water quality and diffuse pollution by agriculture, and emphasize more integration or separation in organization and programs. On the other hand, they can vary in the ‘outcomes’ in terms of more source-based measures or effect-based measures and the emphasis in policy instruments used. This article is based on the screening of policy documents, 44 interviews and several (international) feedback workshops. We found a great variety in governance approaches, while the nature of measures, in terms of source-based and effect-based, is only slightly different. On closer inspection, there are interesting differences in the consensual or antagonist discourses and differences in the use of more mandatory instruments or area-based policies. In many countries, the major challenge is to strike a balance between taking source-based measures, where necessary, and accommodating the difficult situations farmers very often find themselves in, as the reduction of nutrients (as a source-based measure) use can lead to lower yields and higher costs for manure disposal. Full article

(This article belongs to the Special Issue Water Quality and Agricultural Diffuse Pollution in Light of the EU Water Framework Directive)

13 pages, 2686 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Evaluation of Common Supermarket Products as Positive Controls in Biochemical Methane Potential (BMP) Tests

by Konrad Koch, Sasha D. Hafner, Sergi Astals and Sören Weinrich

Water 2020, 12(5), 1223; https://doi.org/10.3390/w12051223 - 25 Apr 2020

Cited by 13 | Viewed by 4433

Abstract

Biochemical methane potential (BMP) tests are commonly applied to evaluate the recoverable amount of methane from a substrate. Standardized protocols require inclusion of a positive control with a known BMP to check the experimental setup and execution, as well as the performance of [...] Read more.

Biochemical methane potential (BMP) tests are commonly applied to evaluate the recoverable amount of methane from a substrate. Standardized protocols require inclusion of a positive control with a known BMP to check the experimental setup and execution, as well as the performance of the inoculum. Only if the BMP of the positive control is within the expected range is the entire test validated. Besides ignorance of this requirement, limited availability of the standard positive control microcrystalline cellulose might be the main reason for neglecting a positive control. To address this limitation, eight widely available grocery store products have been tested as alternative positive controls (APC) to demonstrate their suitability. Among them, Tic Tacs and gummi bears were very promising, although they are dominated by easily degradable sugars and so do not test for hydrolytic performance. Coffee filters exhibited a similar performance to microcrystalline cellulose, while whole milk might be chosen when a more balanced carbohydrate:protein:lipid ratio is important. Overall, the approach of predicting the BMP of a substrate based on the nutritional composition provided on the product packaging worked surprisingly well: BMP of the eight tested products was 81–91% of theoretical maximum BMP based on nutritional information and generic chemical formulas for carbohydrates, proteins, and lipids. Full article

(This article belongs to the Special Issue Biomethane Potential Tests—A Key Tool for Anaerobic Digestion Research and Practice)

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18 pages, 9280 KiB

Open AccessEditor’s ChoiceArticle

Time-Lapse Seismic and Electrical Monitoring of the Vadose Zone during a Controlled Infiltration Experiment at the Ploemeur Hydrological Observatory, France

by Lara A. Blazevic, Ludovic Bodet, Sylvain Pasquet, Niklas Linde, Damien Jougnot and Laurent Longuevergne

Water 2020, 12(5), 1230; https://doi.org/10.3390/w12051230 - 25 Apr 2020

Cited by 26 | Viewed by 5395

Abstract

The vadose zone is the main host of surface and subsurface water exchange and has important implications for ecosystems functioning, climate sciences, geotechnical engineering, and water availability issues. Geophysics provides a means for investigating the subsurface in a non-invasive way and at larger [...] Read more.

The vadose zone is the main host of surface and subsurface water exchange and has important implications for ecosystems functioning, climate sciences, geotechnical engineering, and water availability issues. Geophysics provides a means for investigating the subsurface in a non-invasive way and at larger spatial scales than conventional hydrological sensors. Time-lapse hydrogeophysical applications are especially useful for monitoring flow and water content dynamics. Largely dominated by electrical and electromagnetic methods, such applications increasingly rely on seismic methods as a complementary approach to describe the structure and behavior of the vadose zone. To further explore the applicability of active seismics to retrieve quantitative information about dynamic processes in near-surface time-lapse settings, we designed a controlled water infiltration experiment at the Ploemeur Hydrological Observatory (France) during which successive periods of infiltration were followed by surface-based seismic and electrical resistivity acquisitions. Water content was monitored throughout the experiment by means of sensors at different depths to relate the derived seismic and electrical properties to water saturation changes. We observe comparable trends in the electrical and seismic responses during the experiment, highlighting the utility of the seismic method to monitor hydrological processes and unsaturated flow. Moreover, petrophysical relationships seem promising in providing quantitative results. Full article

(This article belongs to the Special Issue Applied Geophysics in Hydrogeological Practice)

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16 pages, 3006 KiB

Open AccessEditor’s ChoiceArticle

Impact of Microplastic Fibers from the Degradation of Nonwoven Synthetic Textiles to the Magdalena River Water Column and River Sediments by the City of Neiva, Huila (Colombia)

by Paula Martínez Silva and Mark A. Nanny

Water 2020, 12(4), 1210; https://doi.org/10.3390/w12041210 - 24 Apr 2020

Cited by 71 | Viewed by 9579

Abstract

Magdalena River surface water and shoreline sediments were sampled for microplastic particles at three locations in the city of Neiva, Colombia: upstream, city center, and downstream of the raw wastewater outflow. The absence of an industrial and manufacturing sector in Neiva provided an [...] Read more.

Magdalena River surface water and shoreline sediments were sampled for microplastic particles at three locations in the city of Neiva, Colombia: upstream, city center, and downstream of the raw wastewater outflow. The absence of an industrial and manufacturing sector in Neiva provided an opportunity to assess the impact of upstream agricultural practices, as well as municipal activities such as wastewater outflow and laundry washing, on the quantity, polymer composition, and morphology of microplastic particles produced per capita and entering a river system. Microplastic particle concentrations increased with downstream distance, with microfiber concentrations ranging from 0.097 to 0.135 fibers/L in the river water and 25.5 to 102.4 fibers/kg in shoreline sediment. Microplastic fragment concentrations were 0.013–0.028 fragments/L in surface water and 10.4–12.7 fragments/kg of sediment. Raman microscope and scanning electron microscopy identified the relative composition of the polymers comprising the microplastic particles was similar regardless of sampling site or whether the sample was collected from the surface water or shoreline sediments, with polypropylene and polyethylene comprising at least 75% of the total polymers in all samples. Average fiber widths of < 20 µm in all but one sample, along with the lack of acrylic and polyester fibers used predominantly in woven synthetic textiles, indicated that the degradation of nonwoven synthetic textiles is the predominant origin of these microplastic fibers in the Magdalena River. Full article

(This article belongs to the Special Issue Water Quality Impacts of Contaminant Transport and Transformation)

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16 pages, 3202 KiB

Open AccessEditor’s ChoiceArticle

Systems Approach to Management of Water Resources—Toward Performance Based Water Resources Engineering

by Slobodan P. Simonovic

Water 2020, 12(4), 1208; https://doi.org/10.3390/w12041208 - 24 Apr 2020

Cited by 22 | Viewed by 6964

Abstract

Global change, that results from population growth, global warming and land use change (especially rapid urbanization), is directly affecting the complexity of water resources management problems and the uncertainty to which they are exposed. Both, the complexity and the uncertainty, are the result [...] Read more.

Global change, that results from population growth, global warming and land use change (especially rapid urbanization), is directly affecting the complexity of water resources management problems and the uncertainty to which they are exposed. Both, the complexity and the uncertainty, are the result of dynamic interactions between multiple system elements within three major systems: (i) the physical environment; (ii) the social environment; and (iii) the constructed infrastructure environment including pipes, roads, bridges, buildings, and other components. Recent trends in dealing with complex water resources systems include consideration of the whole region being affected, explicit incorporation of all costs and benefits, development of a large number of alternative solutions, and the active (early) involvement of all stakeholders in the decision-making. Systems approaches based on simulation, optimization, and multi-objective analyses, in deterministic, stochastic and fuzzy forms, have demonstrated in the last half of last century, a great success in supporting effective water resources management. This paper explores the future opportunities that will utilize advancements in systems theory that might transform management of water resources on a broader scale. The paper presents performance-based water resources engineering as a methodological framework to extend the role of the systems approach in improved sustainable water resources management under changing conditions (with special consideration given to rapid climate destabilization). An illustrative example of a water supply network management under changing conditions is used to convey the basic principles of performance-based water resources engineering methodology. Full article

(This article belongs to the Special Issue Application of the Systems Approach to the Management of Complex Water Systems)

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17 pages, 2182 KiB

Open AccessEditor’s ChoiceReview

A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels

by Soumen Maji, Prashanth Reddy Hanmaiahgari, Ram Balachandar, Jaan H. Pu, Ana M. Ricardo and Rui M.L. Ferreira

Water 2020, 12(4), 1218; https://doi.org/10.3390/w12041218 - 24 Apr 2020

Cited by 30 | Viewed by 6064

Abstract

This review paper addresses the structure of the mean flow and key turbulence quantities in free-surface flows with emergent vegetation. Emergent vegetation in open channel flow affects turbulence, flow patterns, flow resistance, sediment transport, and morphological changes. The last 15 years have witnessed [...] Read more.

This review paper addresses the structure of the mean flow and key turbulence quantities in free-surface flows with emergent vegetation. Emergent vegetation in open channel flow affects turbulence, flow patterns, flow resistance, sediment transport, and morphological changes. The last 15 years have witnessed significant advances in field, laboratory, and numerical investigations of turbulent flows within reaches of different types of emergent vegetation, such as rigid stems, flexible stems, with foliage or without foliage, and combinations of these. The influence of stem diameter, volume fraction, frontal area of stems, staggered and non-staggered arrangements of stems, and arrangement of stems in patches on mean flow and turbulence has been quantified in different research contexts using different instrumentation and numerical strategies. In this paper, a summary of key findings on emergent vegetation flows is offered, with particular emphasis on: (1) vertical structure of flow field, (2) velocity distribution, 2nd order moments, and distribution of turbulent kinetic energy (TKE) in horizontal plane, (3) horizontal structures which includes wake and shear flows and, (4) drag effect of emergent vegetation on the flow. It can be concluded that the drag coefficient of an emergent vegetation patch is proportional to the solid volume fraction and average drag of an individual vegetation stem is a linear function of the stem Reynolds number. The distribution of TKE in a horizontal plane demonstrates that the production of TKE is mostly associated with vortex shedding from individual stems. Production and dissipation of TKE are not in equilibrium, resulting in strong fluxes of TKE directed outward the near wake of each stem. In addition to Kelvin–Helmholtz and von Kármán vortices, the ejections and sweeps have profound influence on sediment dynamics in the emergent vegetated flows. Full article

(This article belongs to the Special Issue Advances in Modelling and Prediction on the Impact of Human Activities and Extreme Events on Environments)

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26 pages, 4715 KiB

Open AccessEditor’s ChoiceArticle

Impacts of Climate Change and Land Use/Cover Change on Streamflow in Beichuan River Basin in Qinghai Province, China

by Zhe Liu, Lan Cuo, Qijiang Li, Xisheng Liu, Xuelian Ma, Liqiao Liang and Jin Ding

Water 2020, 12(4), 1198; https://doi.org/10.3390/w12041198 - 23 Apr 2020

Cited by 32 | Viewed by 4181

Abstract

Climate change (CC) and land use/cover change (LUCC) are the main drivers of streamflow change. In this study, the effects of CC and LUCC on streamflow regime as well as their spatial variability were examined by using the Distributed Hydrology Soil Vegetation Model [...] Read more.

Climate change (CC) and land use/cover change (LUCC) are the main drivers of streamflow change. In this study, the effects of CC and LUCC on streamflow regime as well as their spatial variability were examined by using the Distributed Hydrology Soil Vegetation Model (DHSVM) for the Beichuan River Basin in the northeast Tibetan Plateau. The results showed that CC increased annual and maximum streamflow in the upstream but decreased them in the downstream. CC also enhanced minimum streamflow in the whole river basin and advanced the occurrence of daily minimum streamflow. Temperature change exerted greater influence on streamflow regime than wind speed change did in most situations, but the impact of wind speed on streamflow reflected the characteristics of accumulative effects, which may require more attention in future, especially in large river basins. As for LUCC, cropland expansion and reservoir operation were the primary reasons for streamflow reduction. Cropland expansion contributed more to annual mean streamflow change, whereas reservoir operation greatly altered monthly streamflow pattern and extreme streamflow. Reservoir regulation also postponed the timing of minimum streamflow and extended durations of average, high, and low streamflow. Spatially, CC and LUCC played predominant roles in the upstream and the downstream, respectively. Full article

(This article belongs to the Special Issue Hydrological Impacts of Climate Change and Land Use)

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19 pages, 4329 KiB

Open AccessEditor’s ChoiceArticle

Machine Learning Approaches for Predicting Health Risk of Cyanobacterial Blooms in Northern European Lakes

by Nikolaos Mellios, S. Jannicke Moe and Chrysi Laspidou

Water 2020, 12(4), 1191; https://doi.org/10.3390/w12041191 - 22 Apr 2020

Cited by 20 | Viewed by 5916

Abstract

Cyanobacterial blooms are considered a major threat to global water security with documented impacts on lake ecosystems and public health. Given that cyanobacteria possess highly adaptive traits that favor them to prevail under different and often complicated stressor regimes, predicting their abundance is [...] Read more.

Cyanobacterial blooms are considered a major threat to global water security with documented impacts on lake ecosystems and public health. Given that cyanobacteria possess highly adaptive traits that favor them to prevail under different and often complicated stressor regimes, predicting their abundance is challenging. A dataset from 822 Northern European lakes is used to determine which variables better explain the variation of cyanobacteria biomass (CBB) by means of stepwise multiple linear regression. Chlorophyll-a (Chl-a) and total nitrogen (TN) provided the best modelling structure for the entire dataset, while for subsets of shallow and deep lakes, Chl-a, mean depth, TN and TN/TP explained part of the variance in CBB. Path analysis was performed and corroborated these findings. Finally, CBB was translated to a categorical variable according to risk levels for human health associated with the use of lakes for recreational activities. Several machine learning methods, namely Decision Tree, K-Nearest Neighbors, Support-vector Machine and Random Forest, were applied showing a remarkable ability to predict the risk, while Random Forest parameters were tuned and optimized, achieving a 95.81% accuracy, exceeding the performance of all other machine learning methods tested. A confusion matrix analysis is performed for all machine learning methods, identifying the potential of each method to correctly predict CBB risk levels and assessing the extent of false alarms; random forest clearly outperforms the other methods with very promising results. Full article

(This article belongs to the Special Issue Water Resources Management: Advances in Machine Learning Approaches)

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24 pages, 2793 KiB

Open AccessEditor’s ChoiceArticle

Nitrogen Surplus—A Unified Indicator for Water Pollution in Europe?

by Susanne Klages, Claudia Heidecke, Bernhard Osterburg, John Bailey, Irina Calciu, Clare Casey, Tommy Dalgaard, Hanna Frick, Matjaž Glavan, Karoline D’Haene, Georges Hofman, Inês Amorim Leitão, Nicolas Surdyk, Koos Verloop and Gerard Velthof

Water 2020, 12(4), 1197; https://doi.org/10.3390/w12041197 - 22 Apr 2020

Cited by 37 | Viewed by 8311

Abstract

Pollution of ground-and surface waters with nitrates from agricultural sources poses a risk to drinking water quality and has negative impacts on the environment. At the national scale, the gross nitrogen budget (GNB) is accepted as an indicator of pollution caused by nitrates. [...] Read more.

Pollution of ground-and surface waters with nitrates from agricultural sources poses a risk to drinking water quality and has negative impacts on the environment. At the national scale, the gross nitrogen budget (GNB) is accepted as an indicator of pollution caused by nitrates. There is, however, little common EU-wide knowledge on the budget application and its comparability at the farm level for the detection of ground-and surface water pollution caused by nitrates and the monitoring of mitigation measures. Therefore, a survey was carried out among experts of various European countries in order to assess the practice and application of fertilization planning and nitrogen budgeting at the farm level and the differences between countries within Europe. While fertilization planning is practiced in all of the fourteen countries analyzed in this paper, according to current legislation, nitrogen budgets have to be calculated only in Switzerland, Germany and Romania. The survey revealed that methods of fertilization planning and nitrogen budgeting at the farm level are not unified throughout Europe. In most of the cases where budgets are used regularly (Germany, Romania, Switzerland), standard values for the chemical composition of feed, organic fertilizers, animal and plant products are used. The example of the Dutch Annual Nutrient Cycling Assessment (ANCA) tool (and partly of the Suisse Balance) shows that it is only by using farm-specific “real” data that budgeting can be successfully applied to optimize nutrient flows and increase N efficiencies at the farm level. However, this approach is more elaborate and requires centralized data processing under consideration of data protection concerns. This paper concludes that there is no unified indicator for nutrient management and water quality at the farm level. A comparison of regionally calculated nitrogen budgets across European countries needs to be interpreted carefully, as methods as well as data and emission factors vary across countries. For the implementation of EU nitrogen-related policies—notably, the Nitrates Directive—nutrient budgeting is currently ruled out as an entry point for legal requirements. In contrast, nutrient budgets are highlighted as an environment indicator by the OECD and EU institutions. Full article

(This article belongs to the Special Issue Land Use and Water Quality)

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13 pages, 1522 KiB

Open AccessEditor’s ChoiceArticle

Recent Trends in Freshwater Influx to the Arctic Ocean from Four Major Arctic-Draining Rivers

by Roxanne Ahmed, Terry Prowse, Yonas Dibike, Barrie Bonsal and Hayley O’Neil

Water 2020, 12(4), 1189; https://doi.org/10.3390/w12041189 - 21 Apr 2020

Cited by 54 | Viewed by 6027

Abstract

Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean [...] Read more.

Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean dynamics through thermohaline circulation; hence, variability in freshwater input from the Arctic flowing rivers has important implications for the global climate system. Daily discharge data from each of the four largest Arctic-draining river watersheds (Mackenzie, Ob, Lena and Yenisei; herein referred to as MOLY) are analyzed to identify historic changes in the magnitude and timing of freshwater input to the Arctic Ocean with emphasis on the spring freshet. Results show that the total freshwater influx to the Arctic Ocean increased by 89 km³/decade, amounting to a 14% increase during the 30-year period from 1980 to 2009. A distinct shift towards earlier melt timing is also indicated by proportional increases in fall, winter and spring discharges (by 2.5%, 1.3% and 2.5% respectively) followed by a decrease (by 5.8%) in summer discharge as a percentage of the mean annual flow. This seasonal increase in discharge and earlier pulse onset dates indicates a general shift towards a flatter, broad-based hydrograph with earlier peak discharges. The study also reveals that the increasing trend in freshwater discharge to the Arctic Ocean is not solely due to increased spring freshet discharge, but is a combination of increases in all seasons except that of the summer. Full article

(This article belongs to the Special Issue Hydrology of the Arctic Region)

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14 pages, 1533 KiB

Open AccessEditor’s ChoiceArticle

A Critical Evaluation of the Water Supply and Stormwater Management Performance of Retrofittable Domestic Rainwater Harvesting Systems

by Ruth Quinn, Peter Melville-Shreeve, David Butler and Virginia Stovin

Water 2020, 12(4), 1184; https://doi.org/10.3390/w12041184 - 21 Apr 2020

Cited by 14 | Viewed by 4327

Abstract

Rainwater harvesting systems are often used as both an alternative water source and a stormwater management tool. Many studies have focused on the water-saving potential of these systems, but research into aspects that impact stormwater retention—such as demand patterns and climate change—is lacking. [...] Read more.

Rainwater harvesting systems are often used as both an alternative water source and a stormwater management tool. Many studies have focused on the water-saving potential of these systems, but research into aspects that impact stormwater retention—such as demand patterns and climate change—is lacking. This paper investigates the short-term impact of demand on both water supply and stormwater management and examines future and potential performance over a longer time scale using climate change projections. To achieve this, data was collected from domestic rainwater harvesting systems in Broadhempston, UK, and used to create a yield-after-spillage model. The validation process showed that using constant demand as opposed to monitored data had little impact on accuracy. With regards to stormwater management, it was found that monitored households did not use all the non-potable available water, and that increasing their demand for this was the most effective way of increasing retention capacity based on the modelling study completed. Installing passive or active runoff control did not markedly improve performance. Passive systems reduced the outflow to greenfield runoff for the longest time, whereas active systems increased the outflow to a level substantially above roof runoff in the 30 largest events. Full article

(This article belongs to the Special Issue Rainwater and Stormwater Harvesting for Sustainable Water Cycle Management)

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24 pages, 3956 KiB

Open AccessEditor’s ChoiceArticle

Assessing the Benefits of Forested Riparian Zones: A Qualitative Index of Riparian Integrity Is Positively Associated with Ecological Status in European Streams

by Francis J. Burdon, Ellinor Ramberg, Jasmina Sargac, Marie Anne Eurie Forio, Nancy de Saeyer, Petra Thea Mutinova, Therese Fosholt Moe, Mihaela Oprina Pavelescu, Valentin Dinu, Constantin Cazacu, Felix Witing, Benjamin Kupilas, Ulf Grandin, Martin Volk, Geta Rîşnoveanu, Peter Goethals, Nikolai Friberg, Richard K. Johnson and Brendan G. McKie

Water 2020, 12(4), 1178; https://doi.org/10.3390/w12041178 - 20 Apr 2020

Cited by 51 | Viewed by 11220

Abstract

Developing a general, predictive understanding of ecological systems requires knowing how much structural and functional relationships can cross scales and contexts. Here, we introduce the CROSSLINK project that investigates the role of forested riparian buffers in modified European landscapes by measuring a wide [...] Read more.

Developing a general, predictive understanding of ecological systems requires knowing how much structural and functional relationships can cross scales and contexts. Here, we introduce the CROSSLINK project that investigates the role of forested riparian buffers in modified European landscapes by measuring a wide range of ecosystem attributes in stream-riparian networks. CROSSLINK involves replicated field measurements in four case-study basins with varying levels of human development: Norway (Oslo Fjord), Sweden (Lake Mälaren), Belgium (Zwalm River), and Romania (Argeş River). Nested within these case-study basins include multiple, independent stream-site pairs with a forested riparian buffer and unbuffered section located upstream, as well as headwater and downstream sites to show cumulative land-use impacts. CROSSLINK applies existing and bespoke methods to describe habitat conditions, biodiversity, and ecosystem functioning in aquatic and terrestrial habitats. Here, we summarize the approaches used, detail protocols in supplementary materials, and explain how data is applied in an optimization framework to better manage tradeoffs in multifunctional landscapes. We then present results demonstrating the range of riparian conditions present in our case-study basins and how these environmental states influence stream ecological integrity with the commonly used macroinvertebrate Average Score Per Taxon (ASPT) index. We demonstrate that a qualitative index of riparian integrity can be positively associated with stream ecological status. This introduction to the CROSSLINK project shows the potential for our replicated study with its panoply of ecosystem attributes to help guide management decisions regarding the use of forested riparian buffers in human-impacted landscapes. This knowledge is highly relevant in a time of rapid environmental change where freshwater biodiversity is increasingly under pressure from a range of human impacts that include habitat loss, pollution, and climate change. Full article

(This article belongs to the Special Issue Ecosystem Functioning in Rivers and Riparian Zones)

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23 pages, 3785 KiB

Open AccessEditor’s ChoiceArticle

Application of Random Forest and ICON Models Combined with Weather Forecasts to Predict Soil Temperature and Water Content in a Greenhouse

by Yi-Zhih Tsai, Kan-Sheng Hsu, Hung-Yu Wu, Shu-I Lin, Hwa-Lung Yu, Kuo-Tsang Huang, Ming-Che Hu and Shao-Yiu Hsu

Water 2020, 12(4), 1176; https://doi.org/10.3390/w12041176 - 20 Apr 2020

Cited by 19 | Viewed by 3898

Abstract

Climate change might potentially cause extreme weather events to become more frequent and intense. It could also enhance water scarcity and reduce food security. More efficient water management techniques are thus required to ensure a stable food supply and quality. Maintaining proper soil [...] Read more.

Climate change might potentially cause extreme weather events to become more frequent and intense. It could also enhance water scarcity and reduce food security. More efficient water management techniques are thus required to ensure a stable food supply and quality. Maintaining proper soil water content and soil temperature is necessary for efficient water management in agricultural practices. The usage of water and fertilizers can be significantly improved with a precise water content prediction tool. In this study, we proposed a new framework that combines weather forecast data, numerical models, and machine learning methods to simulate and predict the soil temperature and volumetric water content in a greenhouse. To test the framework, we performed greenhouse experiments with cherry tomatoes. The numerical models and machine learning methods we selected were Newton’s law of cooling, HYDRUS-1D, the random forest model, and the ICON (inferring connections of networks) model. The measured air temperature, soil temperature, and volumetric water content during the cultivation period were used for model calibration and validation. We compared the performances of the models for soil temperature and volumetric water content predictions. The results showed that the random forest model performed a more accurate prediction than other methods under the limited information provided from greenhouse experiments. This approach provides a framework that can potentially learn best water management practices from experienced farmers and provide intelligent information for smart greenhouse management. Full article

(This article belongs to the Section Hydrology)

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22 pages, 14105 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Multi-Satellite Precipitation Products and Their Ability in Capturing the Characteristics of Extreme Climate Events over the Yangtze River Basin, China

by Shuai Xiao, Jun Xia and Lei Zou

Water 2020, 12(4), 1179; https://doi.org/10.3390/w12041179 - 20 Apr 2020

Cited by 39 | Viewed by 4094

Abstract

Against the background of global climate change and anthropogenic stresses, extreme climate events (ECEs) are projected to increase in both frequency and intensity. Precipitation is one of the main climate parameters for ECE analysis. However, accurate precipitation information for extreme climate events research [...] Read more.

Against the background of global climate change and anthropogenic stresses, extreme climate events (ECEs) are projected to increase in both frequency and intensity. Precipitation is one of the main climate parameters for ECE analysis. However, accurate precipitation information for extreme climate events research from dense rain gauges is still difficult to obtain in mountainous or economically disadvantaged regions. Satellite precipitation products (SPPs) with high spatial and temporal resolution offer opportunities to monitor ECE intensities and trends on large spatial scales. In this study, the accuracies of seven SPPs on multiple spatiotemporal scales in the Yangtze River Basin (YRB) during the period of 2003–2017 are evaluated, along with their ability to capture ECE characteristics. The seven products are the Tropical Rainfall Measuring Mission, Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS) (25), CHIRPS (05), Climate Prediction Center Morphing (CMORPH), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN)-Climate Data Record, PERSIANN-Cloud Classification System, and Global Precipitation Measurement (GPM) IMERG. Rain gauge precipitation data provided by the China Meteorological Administration are adopted as reference data. Various statistical evaluation metrics and different ECE indexes are used to evaluate and compare the performances of the selected products. The results show that CMORPH has the best agreement with the reference data on the daily and annual scales, but GPM IMERG performs relatively well on the monthly scale. With regard to ECE monitoring in the YRB, in general, GPM IMERG and CMORPH provide higher precision. As regards the spatial heterogeneity of the SPP performance in the YRB, most of the examined SPPs have poor accuracy in the mountainous areas of the upper reach. Only CMORPH and GPM IMERG exhibit superior performance; this is because they feature an improved inversion precipitation algorithm for mountainous areas. Furthermore, most SPPs have poor ability to capture extreme precipitation in the estuaries of the lower reach and to monitor drought in the mountainous areas of the upper reach. This study can provide a reference for SPP selection for ECE analysis. Full article

(This article belongs to the Special Issue Remote Sensing in Water Cycle Management)

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18 pages, 4426 KiB

Open AccessEditor’s ChoiceArticle

Linking the Recent Glacier Retreat and Depleting Streamflow Patterns with Land System Changes in Kashmir Himalaya, India

by Irfan Rashid, Ulfat Majeed, Sheikh Aneaus and Mauri Pelto

Water 2020, 12(4), 1168; https://doi.org/10.3390/w12041168 - 19 Apr 2020

Cited by 42 | Viewed by 7506

Abstract

This study reports the changes in glacier extent and streamflow similar to many Himalayan studies, but takes the unusual step of also linking these to downstream land use changes in Kashmir Valley. This study assessed changes in the area, snout, and equilibrium line [...] Read more.

This study reports the changes in glacier extent and streamflow similar to many Himalayan studies, but takes the unusual step of also linking these to downstream land use changes in Kashmir Valley. This study assessed changes in the area, snout, and equilibrium line altitude (ELA) of four parts of the Kolahoi Glacier using earth observation data from 1962 to 2018. Changes in the discharge of the two streams flowing out from Kolahoi Glacier into the Jhelum basin were also assessed between 1972 and 2018. Additionally, satellite data was used to track the downstream land system changes concerning agriculture, orchards, and built-up areas between 1980 and 2018. This analysis suggested a cumulative deglaciation of 23.6% at a rate of 0.42% per year from 1962 to 2018. The snout of two larger glaciers, G1 and G2, retreated at a rate of 18.3 m a⁻¹ and 16.4 m a⁻¹, respectively, from 1962 to 2018, although the rate of recession accelerated after 2000. Our analysis also suggested the upward shift of ELA by ≈120 m. The streamflows measured at five sites showed statistically significant depleting trends that have been a factor in forcing extensive land system changes downstream. Although the area under agriculture in Lidder watershed shrunk by 39%, there was a massive expansion of 176% and 476% in orchards and built-up areas, respectively, from 1980 to 2018. The conversion of irrigation-intensive agriculture lands (rice paddy) to less water-intensive orchards is attributed to economic considerations and depleting streamflow. Full article

(This article belongs to the Special Issue Glacier Watershed Responses to Climate Change)

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16 pages, 3906 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Sponge City Construction for Reducing Directly Connected Impervious Areas on Hydrological Responses at the Urban Catchment Scale

by Changmei Liang, Xiang Zhang, Jun Xia, Jing Xu and Dunxian She

Water 2020, 12(4), 1163; https://doi.org/10.3390/w12041163 - 18 Apr 2020

Cited by 25 | Viewed by 4727

Abstract

Low-impact development (LID) has been widely used at both site-specific and local scales to try and mitigate the impact of urban stormwater runoff caused by increasing impervious urban areas. Recently, the concept of a “sponge city” was proposed by the Chinese government, which [...] Read more.

Low-impact development (LID) has been widely used at both site-specific and local scales to try and mitigate the impact of urban stormwater runoff caused by increasing impervious urban areas. Recently, the concept of a “sponge city” was proposed by the Chinese government, which includes LID controls at the source, a pipe drainage system midway, and a drainage system for excess stormwater at the terminal. There is a need to evaluate the effectiveness of sponge city construction at the large urban catchment scale, particularly with different spatial distributions of LIDs that reduce directly connected impervious areas (DCIAs). In this paper, the performances of five design scenarios with different spatial distributions but same sizes of LID controls at the urban catchment scale were analyzed using a geographic information system (GIS) of the United States Environmental Systems Research Institute (ESRI)—based Storm Water Management Model (SWMM) of the United States Environmental Protection Agency (USEPA) and MIKE 11 of Danish Hydraulic Institute (DHI) in Xining City, China. Results confirmed the effectiveness of sponge city construction in reducing the urban stormwater runoff. The hydrological performance reduction was positively correlated and linearly dependent on DCIA reduction. Peak flow reduction was most sensitive to DCIA reduction, followed by runoff volume and peak time. As rainfall intensity increased, the hydrological performance was more sensitive to rainfall intensity than DCIA reduction. Results of this study provide new insights for stormwater managers to implement LID more effectively at the urban catchment scale. Full article

(This article belongs to the Special Issue Advances of Low Impact Development Practices in Urban Watershed)

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22 pages, 6518 KiB

Open AccessEditor’s ChoiceArticle

Modeling Urban Flood Inundation and Recession Impacted by Manholes

by Merhawi GebreEgziabher and Yonas Demissie

Water 2020, 12(4), 1160; https://doi.org/10.3390/w12041160 - 18 Apr 2020

Cited by 31 | Viewed by 8308

Abstract

Urban flooding, caused by unusually intense rainfall and failure of storm water drainage, has become more frequent and severe in many cities around the world. Most of the earlier studies focused on overland flooding caused by intense rainfall, with little attention given to [...] Read more.

Urban flooding, caused by unusually intense rainfall and failure of storm water drainage, has become more frequent and severe in many cities around the world. Most of the earlier studies focused on overland flooding caused by intense rainfall, with little attention given to floods caused by failures of the drainage system. However, the drainage system contributions to flood vulnerability have increased over time as they aged and became inadequate to handle the design floods. Adaption of the drainages for such vulnerability requires a quantitative assessment of their contribution to flood levels and spatial extent during and after flooding events. Here, we couple the one-dimensional Storm Water Management Model (SWMM) to a new flood inundation and recession model (namely FIRM) to characterize the spatial extent and depth of manhole flooding and recession. The manhole overflow from the SWMM model and a fine-resolution elevation map are applied as inputs in FIRM to delineate the spatial extent and depth of flooding during and aftermath of a storm event. The model is tested for two manhole flooding events in the City of Edmonds in Washington, USA. Our two case studies show reasonable match between the observed and modeled flood spatial extents and highlight the importance of considering manholes in urban flood simulations. Full article

(This article belongs to the Special Issue Modelling of Floods in Urban Areas)

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14 pages, 893 KiB

Open AccessEditor’s ChoiceArticle

Assessment of Agricultural Water Productivity in Arid China

by Nana Yan, Bingfang Wu and Weiwei Zhu

Water 2020, 12(4), 1161; https://doi.org/10.3390/w12041161 - 18 Apr 2020

Cited by 10 | Viewed by 3409

Abstract

The water crisis has become increasingly serious, particularly in arid and semiarid areas. Agricultural water productivity (AWP) is an important indicator for evaluating water use efficiency and agricultural water management. This study uses water consumption derived from satellite data, combined with statistical survey [...] Read more.

The water crisis has become increasingly serious, particularly in arid and semiarid areas. Agricultural water productivity (AWP) is an important indicator for evaluating water use efficiency and agricultural water management. This study uses water consumption derived from satellite data, combined with statistical survey information, to analyze the spatiotemporal variations and driving factors of AWP at the region and county scales over the past 15 years (2002–2015) in the Turpan region (China). The results showed the increasing change trends of AWP throughout Turpan and its three counties. A multiple regression analysis was applied to evaluate AWP, agricultural production and water consumption with driving factors. The contribution of agricultural factors (fertilizer amount, pesticide use and irrigation area) was 86.3% for change of production and 93.3% for change of water consumption in Turpan. The synchronous changes associated with the similar factor contributions resulted in a nonsignificant change in AWP for the whole region. However, the significant increase in AWP in Toksun County was caused by a weakened effect of synchronous changes due to the difference between the largest contributing factors (irrigation area for production at 29.3% and temperature for water consumption at 35.4%). The different change trends of the AWP at regional and county levels indicated that agricultural planting structure adjustment could be an effective way to improve water productivity. This paper provides objective and new information to understand the effects of AWP changes at regional and county scales, which is beneficial for irrigation agriculture development in Turpan. Full article

(This article belongs to the Section Water, Agriculture and Aquaculture)

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16 pages, 3253 KiB

Open AccessEditor’s ChoiceArticle

Spatial Rainfall Variability in Urban Environments—High-Density Precipitation Measurements on a City-Scale

by Roman Maier, Gerald Krebs, Markus Pichler, Dirk Muschalla and Günter Gruber

Water 2020, 12(4), 1157; https://doi.org/10.3390/w12041157 - 18 Apr 2020

Cited by 31 | Viewed by 4890

Abstract

Rainfall runoff models are frequently used for design processes for urban infrastructure. The most sensitive input for these models is precipitation data. Therefore, it is crucial to account for temporal and spatial variability of rainfall events as accurately as possible to avoid misleading [...] Read more.

Rainfall runoff models are frequently used for design processes for urban infrastructure. The most sensitive input for these models is precipitation data. Therefore, it is crucial to account for temporal and spatial variability of rainfall events as accurately as possible to avoid misleading simulation results. This paper aims to show the significant errors that can occur by using rainfall measurement resolutions in urban environments that are too coarse. We analyzed the spatial variability of rainfall events from two years with the validated data of 22 rain gauges spread out over an urban catchment of 125 km². By looking at the interstation correlation of the rain gauges for different classes of rainfall intensities, we found that rainfall events with low and intermediate intensities show a good interstation correlation. However, the correlation drops significantly for heavy rainfall events suggesting higher spatial variability for more intense rainstorms. Further, we analyzed the possible deviation from the spatial rainfall interpolation that uses all available rain gauges when reducing the number of rain gauges to interpolate the spatial rainfall for 24 chosen events. With these analyses we found that reducing the available information by half results in deviations of up to 25% for events with return periods shorter than one year and 45% for events with longer return periods. Assuming uniformly distributed rainfall over the entire catchment resulted in deviations of up to 75% and 125%, respectively. These findings are supported by the work of past research projects and underline the necessity of a high spatial measurement density in order to account for spatial variability of intense rainstorms. Full article

(This article belongs to the Special Issue Urban Rainwater and Flood Management)

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15 pages, 1195 KiB

Open AccessEditor’s ChoiceArticle

Potential Application of Chilean Natural Zeolite as a Support Medium in Treatment Wetlands for Removing Ammonium and Phosphate from Wastewater

by Ismael Vera-Puerto, Matias Saravia, Jorge Olave, Carlos Arias, Erica Alarcon and Hugo Valdes

Water 2020, 12(4), 1156; https://doi.org/10.3390/w12041156 - 18 Apr 2020

Cited by 13 | Viewed by 4365

Abstract

This study aims to evaluate the sorption characteristics of

{NH}_{4}^{+}

-N and

{PO}_{4}^{3 -}

-P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. [...] Read more.

This study aims to evaluate the sorption characteristics of

{NH}_{4}^{+}

-N and

{PO}_{4}^{3 -}

-P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. For this purpose, adsorption experiments onto the zeolite were developed in batch assays. The effects of the adsorbent quantity (20 g and 50 g) and particle size (0.2–1.0 mm; 1.5–3.0 mm, and 5.0–8.0 mm) were evaluated in terms of adsorption capacity at different NH₄⁺-N and PO₄⁻³-P concentrations. Then, the obtained laboratory results were adjusted to theoretical models: Saturation-growth-rate and Langmuir. The saturation adsorption of NH₄⁺-N on the zeolite increases at the same time that the initial concentration increases for the same zeolite quantity; however, the saturation values were similar between the different zeolite sizes tested. For PO₄⁻³-P, the adsorption did not have a direct relationship with the initial concentration nor zeolite quantity and better results were only achieved for zeolite sizes of 1.5–3.0 mm. Regarding the Langmuir model, sizes of 1.5–3.0 mm had the best adsorption characteristics, with the maximum adsorption capacity of up to 1.58 mg/g for NH₄⁺-N and up to 0.08 mg/g for PO₄⁻³-P. Therefore, a new material—a natural zeolite from the Maule Region of Chile—is described as a potential support medium for treatment wetlands. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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38 pages, 454 KiB

Open AccessEditor’s ChoiceReview

Biosorption of Water Pollutants by Fungal Pellets

by Adriana Jazmín Legorreta-Castañeda, Carlos Alexander Lucho-Constantino, Rosa Icela Beltrán-Hernández, Claudia Coronel-Olivares and Gabriela A. Vázquez-Rodríguez

Water 2020, 12(4), 1155; https://doi.org/10.3390/w12041155 - 17 Apr 2020

Cited by 68 | Viewed by 9032

Abstract

Fungal biosorption is an environmental biotechnology based on the ability of the fungal cell wall to concentrate harmful water pollutants. Among its advantages are its simplicity, high efficiency, flexibility of operation, and low cost. The biosorptive performance of fungal pellets is getting growing [...] Read more.

Fungal biosorption is an environmental biotechnology based on the ability of the fungal cell wall to concentrate harmful water pollutants. Among its advantages are its simplicity, high efficiency, flexibility of operation, and low cost. The biosorptive performance of fungal pellets is getting growing attention since they offer process advantages over the culture of disperse mycelia, such as an enhanced biomass separation, and a high resilience in severe environmental conditions. In this review, biosorption capacity of fungal pellets towards heavy metals, dyes, phenolic compounds, humic substances, pesticides, and pharmaceuticals was reviewed. Available data about the adsorption capacity of pellets, their removal efficiency, and the operational conditions used were collected and synthesized. The studies relying on biodegradation were discarded to present only the possibilities of fungal pellets for removing these concern pollutants through biosorption. It was found that the biosorption of complex mixtures of pollutants on fungal pellets is scarcely studied, as well as the interfering effect of anions commonly found in water and wastewater. Furthermore, there is a lack of research with real wastewater and at pilot and large scale. These topics need to be further explored to take full advantage of fungal pellets on improving the quality of aquatic systems. Full article

(This article belongs to the Special Issue Microbial Action in Wastewater and Sludge)

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22 pages, 6069 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Statistical and Machine Learning Models for Pipe Failure Modeling in Water Distribution Networks

by Mónica Marcela Giraldo-González and Juan Pablo Rodríguez

Water 2020, 12(4), 1153; https://doi.org/10.3390/w12041153 - 17 Apr 2020

Cited by 53 | Viewed by 6197

Abstract

The application of statistical and Machine Learning models plays a critical role in planning and decision support processes for efficient and reliable Water Distribution Network (WDN) management. Failure models can provide valuable information for prioritizing system rehabilitation even in data scarcity scenarios, such [...] Read more.

The application of statistical and Machine Learning models plays a critical role in planning and decision support processes for efficient and reliable Water Distribution Network (WDN) management. Failure models can provide valuable information for prioritizing system rehabilitation even in data scarcity scenarios, such as developing countries. Few studies have analyzed the performance of more than two models, and examples of case studies in developing countries are insufficient. This study compares various statistical and Machine Learning models to provide useful information to practitioners for the selection of a suitable pipe failure model according to information availability and network characteristics. Three statistical models (i.e., Linear, Poisson, and Evolutionary Polynomial Regressions) were used for failure prediction in groups of pipes. Machine Learning approaches, particularly Gradient-Boosted Tree (GBT), Bayes, Support Vector Machines and Artificial Neuronal Networks (ANNs), were compared in predicting individual pipe failure rates. The proposed approach was applied to a WDN in Bogotá (Colombia). The statistical models showed an acceptable performance (R² between 0.695 and 0.927), but the Poisson Regression was the most suitable for predicting failures in pipes with lower failure rates. Regarding Machine Learning models, Bayes and ANNs exhibited low performance in the prediction of pipe failure condition. The GBT approach had the best performing classifier. Full article

(This article belongs to the Special Issue Urban Water Management: A Pragmatic Approach)

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14 pages, 7557 KiB

Open AccessEditor’s ChoiceArticle

Smoothed Particle Hydrodynamics Modeling with Advanced Boundary Conditions for Two-Dimensional Dam-Break Floods

by Domenica Mirauda, Raffaele Albano, Aurelia Sole and Jan Adamowski

Water 2020, 12(4), 1142; https://doi.org/10.3390/w12041142 - 16 Apr 2020

Cited by 9 | Viewed by 3711

Abstract

To simulate the dynamics of two-dimensional dam-break flow on a dry horizontal bed, we use a smoothed particle hydrodynamics model implementing two advanced boundary treatment techniques: (i) a semi-analytical approach, based on the computation of volume integrals within the truncated portions [...] Read more.

To simulate the dynamics of two-dimensional dam-break flow on a dry horizontal bed, we use a smoothed particle hydrodynamics model implementing two advanced boundary treatment techniques: (i) a semi-analytical approach, based on the computation of volume integrals within the truncated portions of the kernel supports at boundaries and (ii) an extension of the ghost-particle boundary method for mobile boundaries, adapted to free-slip conditions. The trends of the free surface along the channel, and of the impact wave pressures on the downstream vertical wall, were first validated against an experimental case study and then compared with other numerical solutions. The two boundary treatment schemes accurately predicted the overall shape of the primary wave front advancing along the dry bed until its impact with the downstream vertical wall. Compared to data from numerical models in the literature, the present results showed a closer fit to an experimental secondary wave, reflected by the downstream wall and characterized by complex vortex structures. The results showed the reliability of both the proposed boundary condition schemes in resolving violent wave breaking and impact events of a practical dam-break application, producing smooth pressure fields and accurately predicting pressure and water level peaks. Full article

(This article belongs to the Special Issue Observation-Driven Understanding, Prediction, and Management in Hydrological/Hydraulic Hazard and Risk Studies)

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19 pages, 1133 KiB

Open AccessEditor’s ChoiceArticle

Impact of Extreme Drought Climate on Water Security in North Borneo: Case Study of Sabah

by Carolyn Payus, Lim Ann Huey, Farrah Adnan, Andi Besse Rimba, Geetha Mohan, Saroj Kumar Chapagain, Giulia Roder, Alexandros Gasparatos and Kensuke Fukushi

Water 2020, 12(4), 1135; https://doi.org/10.3390/w12041135 - 16 Apr 2020

Cited by 71 | Viewed by 9586

Abstract

For countries in Southeast Asia that mainly rely on surface water as their water resource, changes in weather patterns and hydrological systems due to climate change will cause severely decreased water resource availability. Warm weather triggers more water use and exacerbates the extraction [...] Read more.

For countries in Southeast Asia that mainly rely on surface water as their water resource, changes in weather patterns and hydrological systems due to climate change will cause severely decreased water resource availability. Warm weather triggers more water use and exacerbates the extraction of water resources, which will change the operation patterns of water usage and increase demand, resulting in water scarcity. The occurrence of prolonged drought upsets the balance between water supply and demand, significantly increasing the vulnerability of regions to damaging impacts. The objectives of this study are to identify trends and determine the impacts of extreme drought events on water levels for the major important water dams in the northern part of Borneo, and to assess the risk of water insecurity for the dams. In this context, remote sensing images are used to determine the degree of risk of water insecurity in the regions. Statistical methods are used in the analysis of daily water levels and rainfall data. The findings show that water levels in dams on the North and Northeast Coasts of Borneo are greatly affected by the extreme drought climate caused by the Northeast Monsoon, with mild to the high risk recorded in terms of water insecurity, with only two of the water dams being water-secure. This study shows how climate change has affected water availability throughout the regions. Full article

(This article belongs to the Section Water Use and Scarcity)

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22 pages, 12273 KiB

Open AccessEditor’s ChoiceArticle

Experimental and Numerical Analysis of a Dam-Break Flow through Different Contraction Geometries of the Channel

by Selahattin Kocaman, Hasan Güzel, Stefania Evangelista, Hatice Ozmen-Cagatay and Giacomo Viccione

Water 2020, 12(4), 1124; https://doi.org/10.3390/w12041124 - 15 Apr 2020

Cited by 37 | Viewed by 5934

Abstract

Dam-break wave propagation usually occurs over irregular topography, due for example to natural contraction-expansion of the river bed and to the presence of natural or artificial obstacles. Due to limited available dam-break real-case data, laboratory and numerical modeling studies are significant for understanding [...] Read more.

Dam-break wave propagation usually occurs over irregular topography, due for example to natural contraction-expansion of the river bed and to the presence of natural or artificial obstacles. Due to limited available dam-break real-case data, laboratory and numerical modeling studies are significant for understanding this type of complex flow problems. To contribute to the related field, a dam-break flow over a channel with a contracting reach was investigated experimentally and numerically. Laboratory tests were carried out in a smooth rectangular channel with a horizontal dry bed for three different lateral contraction geometries. A non-intrusive digital imaging technique was utilized to analyze the dam-break wave propagation. Free surface profiles and time variation of water levels in selected sections were obtained directly from three synchronized CCD video camera records through a virtual wave probe. The experimental results were compared against the numerical solution of VOF (Volume of Fluid)-based Shallow Water Equations (SWEs) and Reynolds-Averaged Navier-Stokes (RANS) equations with the k-ε turbulence model. Good agreements were obtained between computed and measured results. However, the RANS solution shows a better correspondence with the experimental results compared with the SWEs one. The presented new experimental data can be used to validate numerical models for the simulation of dam-break flows over irregular topography. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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22 pages, 4830 KiB

Open AccessEditor’s ChoiceArticle

Use of Heavy Metal Content and Modified Water Quality Index to Assess Groundwater Quality in a Semiarid Area

by Ehsan Kamali Maskooni, Mehran Naseri-Rad, Ronny Berndtsson and Kei Nakagawa

Water 2020, 12(4), 1115; https://doi.org/10.3390/w12041115 - 14 Apr 2020

Cited by 62 | Viewed by 6458

Abstract

Groundwater is a major source of drinking and agricultural water supply in arid and semiarid regions. Poor groundwater quality can be a threat to human health especially when it is combined with hazardous pollutants like heavy metals. In this study, an innovative method [...] Read more.

Groundwater is a major source of drinking and agricultural water supply in arid and semiarid regions. Poor groundwater quality can be a threat to human health especially when it is combined with hazardous pollutants like heavy metals. In this study, an innovative method involving entropy weighted groundwater quality index for both physicochemical and heavy metal content was used for a semiarid region. The entropy weighted index was used to assess the groundwater’s suitability for drinking and irrigation purposes. Thus, groundwater from 19 sampling sites was used for analyses of physicochemical properties (electrical conductivity—EC, pH, K⁺, Ca²⁺, Na⁺, SO₄²⁻, Cl⁻, HCO₃⁻, TDS, NO₃⁻, F⁻, biochemical oxygen demand—BOD, dissolved oxygen—DO, and chemical oxygen demand—COD) and heavy metal content (As, Ca, Sb, Se, Zn, Cu, Ba, Mn, and Cr). To evaluate the overall pollution status in the region, heavy metal indices such as the modified heavy metal pollution index (m-HPI), heavy metal evaluation index (HEI), Nemerow index (NeI), and ecological risks of heavy metals (ERI) were calculated and compared. The results showed that Cd concentration plays a significant role in negatively affecting the groundwater quality. Thus, three wells were classified as poor water quality and not acceptable for drinking water supply. The maximum concentration of heavy metals such as Cd, Se, and Sb was higher than permissible limits by the World Health Organization (WHO) standards. However, all wells except one were suitable for agricultural purposes. The advantage of the innovative entropy weighted groundwater quality index for both physicochemical and heavy metal content, is that it permits objectivity when selecting the weights and reduces the error that may be caused by subjectivity. Thus, the new index can be used by groundwater managers and policymakers to better decide the water’s suitability for consumption. Full article

(This article belongs to the Section Water Quality and Contamination)

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16 pages, 4665 KiB

Open AccessEditor’s ChoiceArticle

Numerical Investigation of a High-Speed Electrical Submersible Pump with Different End Clearances

by Ling Zhou, Wanhong Wang, Jianwei Hang, Weidong Shi, Hao Yan and Yong Zhu

Water 2020, 12(4), 1116; https://doi.org/10.3390/w12041116 - 14 Apr 2020

Cited by 41 | Viewed by 3825

Abstract

The end clearance of the impeller is one of the most important structural parameters in the hydraulic design of a high-speed electrical submersible pump (ESP). In this paper, an ESP with a rotating speed of 6000 r/min was taken as the research object. [...] Read more.

The end clearance of the impeller is one of the most important structural parameters in the hydraulic design of a high-speed electrical submersible pump (ESP). In this paper, an ESP with a rotating speed of 6000 r/min was taken as the research object. Numerical calculations were carried out for five different end clearance conditions of 0.1 mm, 0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm, respectively, to obtain the performance and internal flow field under different situation. The simulation results were verified by the pump performance experiment. It showed that the increase of the end clearance led to a decrease of the head and efficiency of the electrical submersible pump. Through the analysis of the internal flow field, it was found that the existence of the end clearance reduced the flow rate and caused free pre-whirl. With the increase of the end clearance, the phenomenon of de-flow in the diffuser passage was aggravated, which further reduced the performance of the electrical submersible pump. Finally, the reasonable recommended value of the end clearance was given, which facilitated the optimization design and engineering application of the high-speed ESP. Full article

(This article belongs to the Special Issue Hydraulic Dynamic Calculation and Simulation)

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12 pages, 897 KiB

Open AccessEditor’s ChoiceArticle

Polyhydroxyalkanoates (PHAs) Production: A Feasible Economic Option for the Treatment of Sewage Sludge in Municipal Wastewater Treatment Plants?

by Dafne Crutchik, Oscar Franchi, Luis Caminos, David Jeison, Marisol Belmonte, Alba Pedrouso, Angeles Val del Rio, Anuska Mosquera-Corral and José Luis Campos

Water 2020, 12(4), 1118; https://doi.org/10.3390/w12041118 - 14 Apr 2020

Cited by 87 | Viewed by 15819

Abstract

Sludge is a by-product of municipal wastewater treatment plants (WWTPs) and its management contributes significantly to the operating costs. Large WWTPs usually have anaerobic sludge digesters to valorize sludge as methane and to reduce its mass. However, the low methane market price opens [...] Read more.

Sludge is a by-product of municipal wastewater treatment plants (WWTPs) and its management contributes significantly to the operating costs. Large WWTPs usually have anaerobic sludge digesters to valorize sludge as methane and to reduce its mass. However, the low methane market price opens the possibility for generating other high value-added products from the organic matter in sludge, such as polyhydroxyalkanoates (PHAs). In this work, the economic feasibility of retrofitting two types of WWTPs to convert them into biofactories of crude PHAs was studied. Two cases were analyzed: (a) a large WWTP with anaerobic sludge digestion; and (b) a small WWTP where sludge is only dewatered. In a two-stage PHA-production system (biomass enrichment plus PHAs accumulation), the minimum PHAs cost would be 1.26 and 2.26 US$/kg PHA-crude for the large and small WWTPs, respectively. In a single-stage process, where a fraction of the secondary sludge (25%) is directly used to accumulate PHAs, the production costs would decrease by around 15.9% (small WWTPs) and 19.0% (large WWTPs), since capital costs associated with bioreactors decrease. Sensitivity analysis showed that the PHA/COD (Chemical Oxygen Demand) yield is the most crucial parameter affecting the production costs. The energy, methane, and sludge management prices also have an essential effect on the production costs, and their effect depends on the WWTP’s size. Full article

(This article belongs to the Special Issue Sewage Sludge Treatment and Reuse)

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16 pages, 9853 KiB

Open AccessEditor’s ChoiceArticle

Tracking Lake and Reservoir Changes in the Nenjiang Watershed, Northeast China: Patterns, Trends, and Drivers

by Baojia Du, Zongming Wang, Dehua Mao, Huiying Li and Hengxing Xiang

Water 2020, 12(4), 1108; https://doi.org/10.3390/w12041108 - 13 Apr 2020

Cited by 7 | Viewed by 3118

Abstract

In terms of evident climate change and human activities, investigating changes in lakes and reservoirs is critical for sustainable protection of water resources and ecosystem management over the Nenjiang watershed (NJW), an eco-sensitive semi-arid region and the third-largest inland waterbody cluster in China. [...] Read more.

In terms of evident climate change and human activities, investigating changes in lakes and reservoirs is critical for sustainable protection of water resources and ecosystem management over the Nenjiang watershed (NJW), an eco-sensitive semi-arid region and the third-largest inland waterbody cluster in China. In this study, we established a multi-temporal dataset documenting lake and reservoir (area ≥ 1 km²) changes in this region using an object-oriented image classification method and Landsat series images from 1980 to 2015. Using the structural equation model (SEM), we analyzed the diverse impacts of climatic and anthropogenic variables on lake changes. Results indicated that lakes experienced significant changes with fluctuations over the past 35 years including obvious declines in the total area (by 42%) and number (by 51%) from 1980 to 2010 and a slight increase in the total lake area and number from 2010 to 2015. More than 235 lakes in the size class of 1–10 km² decreased to small lakes (area < 1 km²), while 59 lakes covering 243.75 km² disappeared. Total reservoir area and number had continuous increases during the investigated 35 years, with an areal expansion of 54.9% from 919 km² to 1422 km², and a number increase by 65.3% from 78 to 129. The SEM revealed that the lake area in the NJW had a significant correlation with the mean annual precipitation (MAP), suggesting that the MAP decline clarified most of the lake shrinkage in the NJW. Furthermore, agricultural consumption of water had potential impacts on lake changes, suggested by the significant relationship between cropland area and lake area. Full article

(This article belongs to the Special Issue Impacts of Anthropogenic Activities on Watersheds in a Changing Climate)

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19 pages, 5589 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Insights into the Photocatalytic Bacterial Inactivation by Flower-Like Bi₂WO₆ under Solar or Visible Light, Through in Situ Monitoring and Determination of Reactive Oxygen Species (ROS)

by Minoo Karbasi, Fathallah Karimzadeh, Keyvan Raeissi, Sami Rtimi, John Kiwi, Stefanos Giannakis and Cesar Pulgarin

Water 2020, 12(4), 1099; https://doi.org/10.3390/w12041099 - 12 Apr 2020

Cited by 35 | Viewed by 4575

Abstract

This study addresses the visible light-induced bacterial inactivation kinetics over a Bi₂WO₆ synthesized catalyst. The systematic investigation was undertaken with Bi₂WO₆ prepared by the complexation of Bi with acetic acid (carboxylate) leading to a flower-like morphology. The [...] Read more.

This study addresses the visible light-induced bacterial inactivation kinetics over a Bi₂WO₆ synthesized catalyst. The systematic investigation was undertaken with Bi₂WO₆ prepared by the complexation of Bi with acetic acid (carboxylate) leading to a flower-like morphology. The characterization of the as-prepared Bi₂WO₆ was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), specific surface area (SSA), and photoluminescence (PL). Under low intensity solar light (<48 mW/cm²), complete bacterial inactivation was achieved within two hours in the presence of the flower-like Bi₂WO₆, while under visible light, the synthesized catalyst performed better than commercial TiO₂. The in situ interfacial charge transfer and local pH changes between Bi₂WO₆ and bacteria were monitored during the bacterial inactivation. Furthermore, the reactive oxygen species (ROS) were identified during Escherichia coli inactivation mediated by appropriate scavengers. The ROS tests alongside the morphological characteristics allowed the proposition of the mechanism for bacterial inactivation. Finally, recycling of the catalyst confirmed the stable nature of the catalyst presented in this study. Full article

(This article belongs to the Special Issue Urban and Industrial Wastewater Disinfection and Decontamination by Advanced Oxidation Processes (AOPs): Current Issues and Future Trends)

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27 pages, 10697 KiB

Open AccessEditor’s ChoiceArticle

Dam Breach Size Comparison for Flood Simulations. A HEC-RAS Based, GIS Approach for Drăcșani Lake, Sitna River, Romania

by Liviu-Marian Albu, Andrei Enea, Marina Iosub and Iuliana-Gabriela Breabăn

Water 2020, 12(4), 1090; https://doi.org/10.3390/w12041090 - 12 Apr 2020

Cited by 33 | Viewed by 7692

Abstract

Floods are the most destructive natural phenomenon, by the total number of casualties, and value of property damage, compared to any other type of natural disaster. However, some of the most destructive flash floods are related to dam breaches or complete collapses, that [...] Read more.

Floods are the most destructive natural phenomenon, by the total number of casualties, and value of property damage, compared to any other type of natural disaster. However, some of the most destructive flash floods are related to dam breaches or complete collapses, that release the large amounts of water, affecting inhabited areas. Worldwide, numerous dams have almost reached or surpassed the estimated construction life span, and pose an increasing risk to structure stability. Considering their continuous degrading state, increasing rainfall aggressiveness, due to climatic changes, technical error, or even human error, there are numerous, potential causes, for which dams could develop breaches and completely fail. This study aims to portray a comparative perspective of flood impact, with real-life consequences, measured by quantifiable parameters, generated from computer simulations of different breach sizes. These parameters include the total flooded surface, water velocity, maximum water depth, number of affected buildings, etc. The analysis was undergone by means of HEC-RAS based 2D hydraulic modeling and GIS, depending on high-accuracy Lidar terrain data and historical hydrological data. As a case study, Drăcșani Lake with the associated Sulița earthfill embankment dam was chosen, being one of the largest and oldest artificial lakes in Romania. Full article

(This article belongs to the Section Hydrology)

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28 pages, 11729 KiB

Open AccessEditor’s ChoiceArticle

Response of Salt Transport and Residence Time to Geomorphologic Changes in an Estuarine System

by Wen-Cheng Liu, Min-Hsin Ke and Hong-Ming Liu

Water 2020, 12(4), 1091; https://doi.org/10.3390/w12041091 - 12 Apr 2020

Cited by 10 | Viewed by 2878

Abstract

Anthropogenic changes in tidal estuaries have significantly altered bathymetry and topography over the past half century. The geomorphic-driven changes in estuarine hydrodynamics and salt transport remain unclear. To explore this issue, a SELFE (Semi-implicit Eulaerian-Lagrangian Finite Element) -based model was developed and utilized [...] Read more.

Anthropogenic changes in tidal estuaries have significantly altered bathymetry and topography over the past half century. The geomorphic-driven changes in estuarine hydrodynamics and salt transport remain unclear. To explore this issue, a SELFE (Semi-implicit Eulaerian-Lagrangian Finite Element) -based model was developed and utilized in a case study in the Danshui River, Taiwan. The model was calibrated and validated using observed water level, current, and salinity data from 2015, 2016, and 2017. The performance of the SELFE model corresponded well to the measured data. Furthermore, the validated model was utilized to analyze the hydrodynamics, residual current, limit of salt intrusion, and residence time under the predevelopment (1981) and present (2015) conditions. The predicted results revealed that the time lag of water surface elevation at both high tide and low tide under the present condition was approximately 0.5–2 h shorter under the predevelopment condition. The residual circulation under the predevelopment condition was stronger than under the present condition for low flow, causing the limit of salt intrusion to extend further upstream under the predevelopment condition compared to the limit of salt intrusion under the present condition. The calculated residence time under the predevelopment condition was longer than the residence time under the present condition. The freshwater discharge input is a dominating factor affecting the salt intrusion and residence time in a tidal estuary. A regression correlation between the maximum distance of salt intrusion and freshwater discharge and a correlation between residence time and freshwater discharge were established to predict the limit of salt intrusion and residence time under the predevelopment and present conditions with different scenarios of freshwater discharge input. Full article

(This article belongs to the Special Issue Hydrodynamics in Estuaries and Coast: Analysis and Modeling)

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13 pages, 2380 KiB

Open AccessEditor’s ChoiceArticle

Lag Times as Indicators of Hydrological Mechanisms Responsible for NO₃-N Flushing in a Forested Headwater Catchment

by Klaudija Sapač, Andrej Vidmar, Nejc Bezak and Simon Rusjan

Water 2020, 12(4), 1092; https://doi.org/10.3390/w12041092 - 12 Apr 2020

Cited by 2 | Viewed by 3799

Abstract

Understanding the temporal variability of the nutrient transport from catchments is essential for planning nutrient loss reduction measures related to land use and climate change. Moreover, observations and analysis of nutrient dynamics in streams draining undisturbed catchments are known to represent a reference [...] Read more.

Understanding the temporal variability of the nutrient transport from catchments is essential for planning nutrient loss reduction measures related to land use and climate change. Moreover, observations and analysis of nutrient dynamics in streams draining undisturbed catchments are known to represent a reference point by which human-influenced catchments can be compared. In this paper, temporal dynamics of nitrate-nitrogen (NO₃-N) flux are investigated on an event basis by analysing observed lag times between data series. More specifically, we studied lag times between the centres of mass of six hydrological and biogeochemical variables, namely discharge, soil moisture at three depths, NO₃-N flux, and the precipitation hyetograph centre of mass. Data obtained by high-frequency measurements (20 min time step) from 29 events were analysed. Linear regression and multiple linear regression (MLR) were used to identify relationships between lag times of the above-mentioned processes. We found that discharge lag time (LAG_Q) and NO₃-N flux lag time (LAG_N) are highly correlated indicating similar temporal response to rainfall. Moreover, relatively high correlation between LAG_N and soil moisture lag times was also detected. The MLR model showed that the most descriptive variable for both LAG_N and LAG_Q is amount of precipitation. For LAG_N, the change of the soil moisture in the upper two layers was also significant, suggesting that the lag times indicate the primarily role of the forest soils as the main source of the NO₃-N flux, whereas the precipitation amount and the runoff formation through the forest soils are the main controlling mechanisms. Full article

(This article belongs to the Special Issue Hydrological Processes in Small Catchments—Runoff and Sediment Yield in Changing Environment)

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21 pages, 4243 KiB

Open AccessEditor’s ChoiceArticle

On the Use of an IoT Integrated System for Water Quality Monitoring and Management in Wastewater Treatment Plants

by Ramón Martínez, Nuria Vela, Abderrazak el Aatik, Eoin Murray, Patrick Roche and Juan M. Navarro

Water 2020, 12(4), 1096; https://doi.org/10.3390/w12041096 - 12 Apr 2020

Cited by 85 | Viewed by 12522

Abstract

The deteriorating water environment demands new approaches and technologies to achieve sustainable and smart management of urban water systems. Wireless sensor networks represent a promising technology for water quality monitoring and management. The use of wireless sensor networks facilitates the improvement of current [...] Read more.

The deteriorating water environment demands new approaches and technologies to achieve sustainable and smart management of urban water systems. Wireless sensor networks represent a promising technology for water quality monitoring and management. The use of wireless sensor networks facilitates the improvement of current centralized systems and traditional manual methods, leading to decentralized smart water quality monitoring systems adaptable to the dynamic and heterogeneous water distribution infrastructure of cities. However, there is a need for a low-cost wireless sensor node solution on the market that enables a cost-effective deployment of this new generation of systems. This paper presents the integration to a wireless sensor network and a preliminary validation in a wastewater treatment plant scenario of a low-cost water quality monitoring device in the close-to-market stage. This device consists of a nitrate and nitrite analyzer based on a novel ion chromatography detection method. The analytical device is integrated using an Internet of Things software platform and tested under real conditions. By doing so, a decentralized smart water quality monitoring system that is conceived and developed for water quality monitoring and management is accomplished. In the presented scenario, such a system allows online near-real-time communication with several devices deployed in multiple water treatment plants and provides preventive and data analytics mechanisms to support decision making. The results obtained comparing laboratory and device measured data demonstrate the reliability of the system and the analytical method implemented in the device. Full article

(This article belongs to the Special Issue Smart Urban Water Networks)

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11 pages, 1940 KiB

Open AccessEditor’s ChoiceArticle

Microplastics Removal from Treated Wastewater by a Biofilter

by Fan Liu, Nadia B. Nord, Kai Bester and Jes Vollertsen

Water 2020, 12(4), 1085; https://doi.org/10.3390/w12041085 - 11 Apr 2020

Cited by 73 | Viewed by 11713

Abstract

Microplastic (MP) pollution is a global environmental issue, and traditionally treated wastewater has been identified as a source of land-based microplastics into the aquatic environment. This study evaluated the performance of a pilot-scale biofilter to polish wastewater treatment plant (WWTP) effluent before it [...] Read more.

Microplastic (MP) pollution is a global environmental issue, and traditionally treated wastewater has been identified as a source of land-based microplastics into the aquatic environment. This study evaluated the performance of a pilot-scale biofilter to polish wastewater treatment plant (WWTP) effluent before it enters the environment. The filter was divided into four zones, allowing the concentration of microplastics to be followed through the filter. It was fed with secondary effluent from a conventional WWTP in Denmark. The raw effluent from the WWTP contained 917 items m⁻³ which corresponded to a mass concentration of 24.8 µg m⁻³. After the top layer of the biofilter, the concentration had decreased to a median value of 197 item m⁻³ and 2.8 µg m⁻³, indicating an overall removal efficiency of 79% in terms of particle number and 89% in terms of particle mass. We also observed a tendency that MP of larger size and higher particle mass were more likely to be retained. After the last filtration zone, all MP larger than 100 µm had been removed. The results of this study demonstrate that biofilters are able to lower the MP abundance in treated wastewater significantly, but a complete removal is not ensured, hence some MP, particularly small-sized ones, can still be discharged into the receiving environment. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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16 pages, 7431 KiB

Open AccessEditor’s ChoiceArticle

Simulating the Hydraulic Heave Phenomenon with Multiphase Fluid Flows Using CFD-DEM

by Qiong Xiao

Water 2020, 12(4), 1077; https://doi.org/10.3390/w12041077 - 9 Apr 2020

Cited by 3 | Viewed by 2727

Abstract

In geotechnical engineering, the seepage phenomena, especially regarding the hydraulic heave, is one of the most dangerous failure mechanisms related to infrastructural stability. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In this study, [...] Read more.

In geotechnical engineering, the seepage phenomena, especially regarding the hydraulic heave, is one of the most dangerous failure mechanisms related to infrastructural stability. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In this study, a computational fluid dynamics (CFD) solver was developed and coupled with discrete element method (DEM) software to simulate the seepage failure process for the three phases of soil, water, and air. Specimens were constructed with two layers of gap-graded particles to give different permeability properties in the vertical direction. More significant heave failure was observed for the sample with higher permeability in the upper layer. Special attention was drawn to the particle-scale observations of the internal structure and drag force to study the erosion mechanism. The soil filled with air bubbles produced a higher drag force in the region below the retaining wall and showed a larger loss of fine particles than the saturated soil, particularly in the initial stages. The results indicate that the impact of air bubbles would accelerate the development of the heave or boiling phenomenon and influence the stability of the system at an early stage. Full article

(This article belongs to the Special Issue Granular Flows Modeling and Simulation)

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23 pages, 377 KiB

Open AccessEditor’s ChoiceReview

Use of Ultrasound as an Advanced Oxidation Process for the Degradation of Emerging Pollutants in Water

by Ana L. Camargo-Perea, Ainhoa Rubio-Clemente and Gustavo A. Peñuela

Water 2020, 12(4), 1068; https://doi.org/10.3390/w12041068 - 9 Apr 2020

Cited by 76 | Viewed by 5449

Abstract

Emerging pollutants are compounds of increased environmental importance and, as such there is interest among researchers in the evaluation of their presence, continuity and elimination in different environmental matrices. The present work reviews the available scientific data on the degradation of emerging pollutants, [...] Read more.

Emerging pollutants are compounds of increased environmental importance and, as such there is interest among researchers in the evaluation of their presence, continuity and elimination in different environmental matrices. The present work reviews the available scientific data on the degradation of emerging pollutants, mainly pharmaceuticals, through ultrasound, as an advanced oxidation process (AOP). This study analyzes the influence of several parameters, such as the nature of the pollutant, the ultrasonic frequency, the electrical power, the pH, the constituents of the matrix and the temperature of the solution on the efficiency of this AOP through researches previously reported in the literature. Additionally, it informs on the application of the referred process alone and/or in combination with other AOPs focusing on the treatment of domestic and industrial wastewaters containing emerging pollutants, mainly pharmaceuticals, as well as on the economic costs associated with and the future perspectives that make ultrasound a possible candidate to solve the problem of water pollution by these emerging pollutants.. Full article

(This article belongs to the Special Issue Urban and Industrial Wastewater Disinfection and Decontamination by Advanced Oxidation Processes (AOPs): Current Issues and Future Trends)

14 pages, 1654 KiB

Open AccessEditor’s ChoiceArticle

Living at the Water’s Edge: A World-Wide Econometric Panel Estimation of Arable Water Footprint Drivers

by Pilar Gracia-de-Rentería, George Philippidis, Hugo Ferrer-Pérez and Ana Isabel Sanjuán

Water 2020, 12(4), 1060; https://doi.org/10.3390/w12041060 - 8 Apr 2020

Cited by 2 | Viewed by 2917

Abstract

As part of the Sustainable Development Goal (SDG) for ensuring clean water and sanitation worldwide by 2030, SDG target 6.4 seeks to attain sustainable withdrawals of freshwater through efficiency gains with a view to relieving water stress in vulnerable populated areas. The water [...] Read more.

As part of the Sustainable Development Goal (SDG) for ensuring clean water and sanitation worldwide by 2030, SDG target 6.4 seeks to attain sustainable withdrawals of freshwater through efficiency gains with a view to relieving water stress in vulnerable populated areas. The water footprint (WF) is a key metric to measure this concept, although the dynamics of the drivers of the WF through space and time remain relatively under-researched, whilst in foresight studies, the WF is often subject to simplistic assumptions. Thus, constructing a panel dataset of 130 countries and 156 crops for the period 2002–2016, this paper empirically assesses the sign and magnitude of WF drivers of agricultural crop activities, employing a careful selection of demographic, economic and climatic drivers. The study uncovers evidence of significant deviations in WF drivers across regions segmented by relative wealth, relating specifically to the stage of economic development and the presence (absence) of economies of scale, whilst we confirm that geographical coordinates have a major bearing on the climatic WF driver. Moreover, examining the temporal dimension, there is compelling evidence supporting a structural break in the role that technical progress exerted on the WF prior to, and in the wake of, the 2008 financial crisis. Full article

(This article belongs to the Special Issue Virtual Water Trade and Water Resources Economics)

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