Water

17 pages, 4260 KiB

Open AccessEditor’s ChoiceArticle

New Sustainable Approach for the Production of Fe₃O₄/Graphene Oxide-Activated Persulfate System for Dye Removal in Real Wastewater

by Md. Nahid Pervez, Wei He, Tiziano Zarra, Vincenzo Naddeo and Yaping Zhao

Water 2020, 12(3), 733; https://doi.org/10.3390/w12030733 - 7 Mar 2020

Cited by 83 | Viewed by 6714

Abstract

Persulfate (PS)-activated, iron-based heterogeneous catalysts have attracted significant attention as a potential advanced and sustainable water purification system. Herein, a novel Fe₃O₄ impregnated graphene oxide (Fe₃O₄@GO)-activated persulfate system (Fe₃O₄@GO+K₂S₂ [...] Read more.

Persulfate (PS)-activated, iron-based heterogeneous catalysts have attracted significant attention as a potential advanced and sustainable water purification system. Herein, a novel Fe₃O₄ impregnated graphene oxide (Fe₃O₄@GO)-activated persulfate system (Fe₃O₄@GO+K₂S₂O₈) was synthesized by following a sustainable protocol and was tested on real wastewater containing dye pollutants. In the presence of the PS-activated system, the degradation efficiency of Rhodamine B (RhB) was significantly increased to a level of ≈95% compared with that of Fe₃O₄ (≈25%). The influences of different operational parameters, including solution pH, persulfate dosage, and RhB concentration, were systemically evaluated. This system maintained its catalytic activity and durability with a negligible amount of iron leached during successive recirculation experiments. The degradation intermediates were further identified through reactive oxygen species (ROS) studies, where surface-bound SO₄⁻ was found to be dominant radical for RhB degradation. Moreover, the degradation mechanism of RhB in the Fe₃O₄@GO+K₂S₂O₈ system was discussed. Finally, the results indicate that the persulfate-activated Fe₃O₄@GO catalyst provided an effective pathway for the degradation of dye pollutants in real wastewater treatment. Full article

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

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24 pages, 2731 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Water Regulation in Cyanobacterial Biocrusts from Drylands: Negative Impacts of Anthropogenic Disturbance

by Yolanda Cantón, Sonia Chamizo, Emilio Rodriguez-Caballero, Roberto Lázaro, Beatriz Roncero-Ramos, José Raúl Román and Albert Solé-Benet

Water 2020, 12(3), 720; https://doi.org/10.3390/w12030720 - 6 Mar 2020

Cited by 51 | Viewed by 4500

Abstract

Arid and semi-arid ecosystems are characterized by patchy vegetation and variable resource availability. The interplant spaces of these ecosystems are very often covered by cyanobacteria-dominated biocrusts, which are the primary colonizers of terrestrial ecosystems and key in facilitating the succession of other biocrust [...] Read more.

Arid and semi-arid ecosystems are characterized by patchy vegetation and variable resource availability. The interplant spaces of these ecosystems are very often covered by cyanobacteria-dominated biocrusts, which are the primary colonizers of terrestrial ecosystems and key in facilitating the succession of other biocrust organisms and plants. Cyanobacterial biocrusts regulate the horizontal and vertical fluxes of water, carbon and nutrients into and from the soil and play crucial hydrological, geomorphological and ecological roles in these ecosystems. In this paper, we analyze the influence of cyanobacterial biocrusts on water balance components (infiltration-runoff, evaporation, soil moisture and non-rainfall water inputs (NRWIs)) in representative semiarid ecosystems in southeastern Spain. The influence of cyanobacterial biocrusts, in two stages of their development, on runoff-infiltration was studied by rainfall simulation and in field plots under natural rainfall at different spatial scales. Results showed that cover, exopolysaccharide content, roughness, organic carbon, total nitrogen, available water holding capacity, aggregate stability, and other properties increased with the development of the cyanobacterial biocrust. Due to the effects on these soil properties, runoff generation was lower in well-developed than in incipient-cyanobacterial biocrusts under both simulated and natural rainfall and on different spatial scales. Runoff yield decreased at coarser spatial scales due to re-infiltration along the hillslope, thus decreasing hydrological connectivity. Soil moisture monitoring at 0.03 m depth revealed higher moisture content and slower soil water loss in plots covered by cyanobacterial biocrusts compared to bare soils. Non-rainfall water inputs were also higher under well-developed cyanobacterial biocrusts than in bare soils. Disturbance of cyanobacterial biocrusts seriously affected the water balance by increasing runoff, decreasing soil moisture and accelerating soil water loss, at the same time that led to a very significant increase in sediment yield. The recovery of biocrust cover after disturbance can be relatively fast, but its growth rate is strongly conditioned by microclimate. The results of this paper show the important influence of cyanobacterial biocrust in modulating the different processes supporting the capacity of these ecosystems to provide key services such as water regulation or erosion control, and also the important impacts of their anthropic disturbance. Full article

(This article belongs to the Special Issue Soil and Water-Related Ecosystem Services)

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18 pages, 3713 KiB

Open AccessEditor’s ChoiceArticle

Comparing the Adsorption Performance of Multiwalled Carbon Nanotubes Oxidized by Varying Degrees for Removal of Low Levels of Copper, Nickel and Chromium(VI) from Aqueous Solutions

by Marko Šolić, Snežana Maletić, Marijana Kragulj Isakovski, Jasmina Nikić, Malcolm Watson, Zoltan Kónya and Jelena Tričković

Water 2020, 12(3), 723; https://doi.org/10.3390/w12030723 - 6 Mar 2020

Cited by 37 | Viewed by 3372

Abstract

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has [...] Read more.

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L⁻¹) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient K_F) ranging from 1.24 to 13.2 (mg g⁻¹)/(mg l⁻¹)ⁿ, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions. Full article

(This article belongs to the Special Issue Advances in In Situ Biological and Chemical Groundwater Treatment)

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16 pages, 3142 KiB

Open AccessEditor’s ChoiceArticle

Flow Resistance Equation in Sand-bed Rivers and Its Practical Application in the Yellow River

by Rongrong Cai, Hongwu Zhang, Yu Zhang, Luohao Zhang and Hai Huang

Water 2020, 12(3), 727; https://doi.org/10.3390/w12030727 - 6 Mar 2020

Cited by 4 | Viewed by 3874

Abstract

To fully reflect the effect of the flow characteristics, sidewall conditions and sediment concentrations on the bed roughness of sand-bed rivers, this study established a new flow resistance equation by introducing a comprehensive influence coefficient presented via a combination of power-function forms of [...] Read more.

To fully reflect the effect of the flow characteristics, sidewall conditions and sediment concentrations on the bed roughness of sand-bed rivers, this study established a new flow resistance equation by introducing a comprehensive influence coefficient presented via a combination of power-function forms of the relative flow velocity, von Karman constant of sediment-laden flows and the ratio of particle size to viscous sublayer thickness. The comprehensive influence coefficient accordingly acts as a synthesized factor representing the combined effects of the flow intensity, bed material movement, energy consumption condition, and relative friction condition in the near-wall region of sediment-laden flows. Based on the field data from sediment-laden flows under scenarios of both high and low sediment concentrations, the performance of the proposed equation was validated to achieve the best accuracy in the calculation of Manning’s roughness coefficient compared with that of several previously presented flow resistance equations. Furthermore, the proposed flow resistance equation was adopted to quantify the stable channel width of the Lower Yellow River (LYR), i.e., the optimum main channel width for sediment transportation in the typical wandering reach of the LYR. The calculated stable channel width is consistent with the current river training width of the LYR, indicating that the proposed equation has great potential as a theoretical tool that can be used to support the determination of the river training strategy for the LYR. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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13 pages, 4708 KiB

Open AccessEditor’s ChoiceArticle

Effect of Pressure Fluctuations and Flow Confinement on Shear Stress in Jet-Driven Scour Processes

by Simone Pagliara and Michele Palermo

Water 2020, 12(3), 718; https://doi.org/10.3390/w12030718 - 6 Mar 2020

Cited by 3 | Viewed by 2563

Abstract

The effect of pressure fluctuations and flow confinement on shear stress still represents a challenging problem for hydraulic engineers. Only a few studies investigated such aspects, but they did not focus on jet-driven scour processes in granular bed material. Following a recent theoretical [...] Read more.

The effect of pressure fluctuations and flow confinement on shear stress still represents a challenging problem for hydraulic engineers. Only a few studies investigated such aspects, but they did not focus on jet-driven scour processes in granular bed material. Following a recent theoretical framework, this paper presents a novel analytical procedure to assess the effect of pressure fluctuations on the average shear stress for 2D equilibrium configuration, under steady, black water flow conditions. The analysis of experimental data evidences that published formulas underestimate the maximum shear stress, because of the significant flow confinement and the presence of rotating material in the scour hole. Therefore, based on the hydrodynamic similitude characterizing the jet diffusion in a confined environment, a new shear stress coefficient and a novel equation are proposed to estimate the maximum shear stress for the tested configuration. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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20 pages, 2440 KiB

Open AccessEditor’s ChoiceArticle

Zooplankton Community Responses to Oxygen Stress

by Maciej Karpowicz, Jolanta Ejsmont-Karabin, Joanna Kozłowska, Irina Feniova and Andrew R. Dzialowski

Water 2020, 12(3), 706; https://doi.org/10.3390/w12030706 - 5 Mar 2020

Cited by 48 | Viewed by 6485

Abstract

Recent changes in climate and eutrophication have caused increases in oxygen depletion in both freshwater and marine ecosystems. However, the impact of oxygen stress on zooplankton, which is the major trophic link between primary producers and fish, remains largely unknown in lakes. Therefore, [...] Read more.

Recent changes in climate and eutrophication have caused increases in oxygen depletion in both freshwater and marine ecosystems. However, the impact of oxygen stress on zooplankton, which is the major trophic link between primary producers and fish, remains largely unknown in lakes. Therefore, we studied 41 lakes with different trophic and oxygen conditions to assess the role of oxygen stress on zooplankton communities and carbon transfer between phytoplankton and zooplankton. Samples were collected from each lake at the peak of summer stratification from three depth layers (the epilimnion, metalimnion, and hypolimnion). Our results revealed that freshwater zooplankton were relatively tolerant to anoxic conditions and the greatest changes in community structure were found in lakes with the highest oxygen deficits. This caused a switch in dominance from large to small species and reduced the zooplankton biomass in lower, anoxic layers of water, but not in the upper layers of water where the oxygen deficits began. This upper anoxic layer could thus be a very important refuge for zooplankton to avoid predation during the day. However, the reduction of zooplankton in the lower water layers was the main factor that reduced the effectiveness of carbon transfer between the phytoplankton and zooplankton. Full article

(This article belongs to the Special Issue The Response of the Plankton Community to Environmental Stress)

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15 pages, 2326 KiB

Open AccessEditor’s ChoiceArticle

Modeling of the Free-Surface-Pressurized Flow of a Hydropower System with a Flat Ceiling Tail Tunnel

by Jianxu Zhou and Yongfa Li

Water 2020, 12(3), 699; https://doi.org/10.3390/w12030699 - 4 Mar 2020

Cited by 4 | Viewed by 2867

Abstract

For a water diversion hydropower system with a flat ceiling tail tunnel with high elevation, during transient states with relatively low tail water levels, free-surface-pressurized flow inevitably appears and its transient characteristics have obvious effects on the system’s operating stability. Using Newton–Raphson linearization [...] Read more.

For a water diversion hydropower system with a flat ceiling tail tunnel with high elevation, during transient states with relatively low tail water levels, free-surface-pressurized flow inevitably appears and its transient characteristics have obvious effects on the system’s operating stability. Using Newton–Raphson linearization in the characteristic implicit format for modeling of the free-surface-pressurized flow in the tail tunnel, the mathematical models for necessary boundary conditions were derived and linear algebraic equations with a band coefficient matrix were grouped for further transient simulation. Then, a unified mathematical model was established for hydraulic transient analysis of the hydropower system with free-surface-pressurized flow. Combined with experimental research and numerical simulation, the wave speed for the free-surface-pressurized flow was experimentally analyzed for further correctness in the unified model, and by comparative analysis the hydraulic characteristics of the free-surface-pressurized flow in the flat ceiling tail tunnel were investigated. It was found that the derived mathematical model can basically represent water behaviors in the water-surface-pressurized flow, the wave speed for the mixed water-surface-pressurized flow can be set to approximately 50m/s, and with this correctness the numerical results are in good agreement with the experimental results. Therefore, the obtained mathematical model combined with an experimental wave speed or a reference wave speed of 50 m/s for the free-surface-pressurized flow is preferable during the design stage of the hydropower system. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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30 pages, 6129 KiB

Open AccessEditor’s ChoiceArticle

GIS Based Hybrid Computational Approaches for Flash Flood Susceptibility Assessment

by Binh Thai Pham, Mohammadtaghi Avand, Saeid Janizadeh, Tran Van Phong, Nadhir Al-Ansari, Lanh Si Ho, Sumit Das, Hiep Van Le, Ata Amini, Saeid Khosrobeigi Bozchaloei, Faeze Jafari and Indra Prakash

Water 2020, 12(3), 683; https://doi.org/10.3390/w12030683 - 2 Mar 2020

Cited by 143 | Viewed by 8742

Abstract

Flash floods are one of the most devastating natural hazards; they occur within a catchment (region) where the response time of the drainage basin is short. Identification of probable flash flood locations and development of accurate flash flood susceptibility maps are important for [...] Read more.

Flash floods are one of the most devastating natural hazards; they occur within a catchment (region) where the response time of the drainage basin is short. Identification of probable flash flood locations and development of accurate flash flood susceptibility maps are important for proper flash flood management of a region. With this objective, we proposed and compared several novel hybrid computational approaches of machine learning methods for flash flood susceptibility mapping, namely AdaBoostM1 based Credal Decision Tree (ABM-CDT); Bagging based Credal Decision Tree (Bag-CDT); Dagging based Credal Decision Tree (Dag-CDT); MultiBoostAB based Credal Decision Tree (MBAB-CDT), and single Credal Decision Tree (CDT). These models were applied at a catchment of Markazi state in Iran. About 320 past flash flood events and nine flash flood influencing factors, namely distance from rivers, aspect, elevation, slope, rainfall, distance from faults, soil, land use, and lithology were considered and analyzed for the development of flash flood susceptibility maps. Correlation based feature selection method was used to validate and select the important factors for modeling of flash floods. Based on this feature selection analysis, only eight factors (distance from rivers, aspect, elevation, slope, rainfall, soil, land use, and lithology) were selected for the modeling, where distance to rivers is the most important factor for modeling of flash flood in this area. Performance of the models was validated and compared by using several robust metrics such as statistical measures and Area Under the Receiver Operating Characteristic (AUC) curve. The results of this study suggested that ABM-CDT (AUC = 0.957) has the best predictive capability in terms of accuracy, followed by Dag-CDT (AUC = 0.947), MBAB-CDT (AUC = 0.933), Bag-CDT (AUC = 0.932), and CDT (0.900), respectively. The proposed methods presented in this study would help in the development of accurate flash flood susceptible maps of watershed areas not only in Iran but also other parts of the world. Full article

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

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15 pages, 10030 KiB

Open AccessEditor’s ChoiceArticle

CFD–DEM Simulations of Seepage-Induced Erosion

by Qiong Xiao and Ji-Peng Wang

Water 2020, 12(3), 678; https://doi.org/10.3390/w12030678 - 2 Mar 2020

Cited by 16 | Viewed by 5616

Abstract

Increases in seepage force reduce the effective stress of particles and result in the erosion of particles, producing heave failure and piping. Sheet piles/cutoff walls are often employed in dams to control the seepage. In this study, a computational fluid dynamics solver involving [...] Read more.

Increases in seepage force reduce the effective stress of particles and result in the erosion of particles, producing heave failure and piping. Sheet piles/cutoff walls are often employed in dams to control the seepage. In this study, a computational fluid dynamics solver involving two fluid phases was developed and coupled with discrete element method software to simulate the piping process around a sheet pile/cutoff wall. Binary-sized particles were selected to study the impact of fine particles on the mechanisms of seepage. The seepage phenomenon mainly appeared among fine particles located in the downstream side, with the peak magnitudes of drag force and displacement occurring around the retaining wall. Based on the particle-scale observations, the impact of seepage produced a looser condition for the region concentrated around the retaining wall and resulted in an anisotropic condition in the soil skeleton. The results indicate that heave behavior occurs when the drag force located adjacent to the boundary on the downstream side is larger than the corresponding weight of the bulk soil. Full article

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

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19 pages, 1019 KiB

Open AccessEditor’s ChoiceArticle

Nexus between Ecological Conservation and Socio-Economic Development and its Dynamics: Insights from a Case in China

by Jian Wu, Yanan Guo and Jingbo Zhou

Water 2020, 12(3), 663; https://doi.org/10.3390/w12030663 - 1 Mar 2020

Cited by 6 | Viewed by 4152

Abstract

Achieving sustainable socio-economic development in areas designated for ecological conservation is a challenge for many developing countries. The nexus between ecological conservation and socio-economic development is particularly complex in these areas for the reason that most of them are located in poor regions [...] Read more.

Achieving sustainable socio-economic development in areas designated for ecological conservation is a challenge for many developing countries. The nexus between ecological conservation and socio-economic development is particularly complex in these areas for the reason that most of them are located in poor regions and their resource utilization is constrained by ecological conservation practices. A conceptual framework was proposed for examining the nexus between ecological conservation and economic development in a social-ecological system to explain the pathways and mechanisms of influence between the ecosystem and the social system. We chose the Lashihai watershed in Yunnan Province, China, as the case study area to explore whether a positive feedback loop between ecological conservation and socio-economic development has been formed, as well as how to promote the positive evolution of socio-economic and ecological status. The ecosystem and socio-economic system in the Lashihai watershed closely interact and form a dynamic system with a positive evolutionary trend. If negative factors, such as an uneven distribution of income and new population pressures, are not appropriately managed, they are likely to break the positive feedback loop and trap the system in a negative feedback loop. We discuss the main factors that contribute to the interactions between ecological conservation and livelihoods, and develop policy recommendations for governments in other countries and regions to promote conservation and better livelihoods in conjunction. Full article

(This article belongs to the Special Issue Water Management Challenges in an Increasingly Warm and Crowded Planet)

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21 pages, 3579 KiB

Open AccessEditor’s ChoiceArticle

Biodiversity of Calanoida Copepoda in Different Habitats of the North-Western Red Sea (Hurghada Shelf)

by Hamdy Abo-Taleb, Mohamed Ashour, Ahmed El-Shafei, Abed Alataway and Mahmoud M. Maaty

Water 2020, 12(3), 656; https://doi.org/10.3390/w12030656 - 29 Feb 2020

Cited by 35 | Viewed by 5187

Abstract

Little is known about the diversity of Calanoida, Copepoda, in different habitats of the north-western Red Sea. In this study, biodiversity of Calanoida, Copepoda, during the cold and warm seasons of 2017, were observed at 12 stations belonging to four different habitats (coral [...] Read more.

Little is known about the diversity of Calanoida, Copepoda, in different habitats of the north-western Red Sea. In this study, biodiversity of Calanoida, Copepoda, during the cold and warm seasons of 2017, were observed at 12 stations belonging to four different habitats (coral reef (CR), sheltered shallow lagoons (SSL), seagrass (SG), and open deep-water (ODW) habitats) in the Hurghada shelf, north-western Red Sea. SSL habitats were the most affected by environmental conditions, especially temperature, salinity, and depth. Some calanoid species were restricted to certain habitats, others were adapted to live in more than one habitat, while some species showed a wide distribution in all habitats. ODW habitats showed maximum diversity and density of the calanoid species. The effects of temperature and salinity were distinct in the SG and SSL. The results clearly showed that different Red Sea habitats affected the biodiversity of calanoid copepods. Full article

(This article belongs to the Special Issue Marine Biology: Biodiversity and Conservation)

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29 pages, 9095 KiB

Open AccessEditor’s ChoiceArticle

Hydrodynamic Modeling and Simulation of Water Residence Time in the Estuary of the Lower Amazon River

by Carlos Henrique M. de Abreu, Maria de Lourdes Cavalcanti Barros, Daímio Chaves Brito, Marcelo Rassy Teixeira and Alan Cavalcanti da Cunha

Water 2020, 12(3), 660; https://doi.org/10.3390/w12030660 - 29 Feb 2020

Cited by 24 | Viewed by 5602

Abstract

Studies about the hydrodynamic behavior in the lower Amazon River remain scarce, despite their relevance and complexity, and the Water Residence Time (Rt) of this Amazonian estuary remains poorly unknown. Therefore, the present study aims to numerically simulate three seasonal Rt scenarios based [...] Read more.

Studies about the hydrodynamic behavior in the lower Amazon River remain scarce, despite their relevance and complexity, and the Water Residence Time (Rt) of this Amazonian estuary remains poorly unknown. Therefore, the present study aims to numerically simulate three seasonal Rt scenarios based on a calibrated hydrodynamic numerical model (SisbaHiA) applied to a representative stretch of the lower Amazon River. The following methodological steps were performed: (a) establishing experimental water flow in natural channels; (b) statistically test numerical predictions (tidal range cycles for different hydrologic periods); and (c) simulating velocity fields and water discharge associated with Rt numerical outputs of the hydrodynamic model varied from 14 ≤ Rt ≤ 22 days among different seasonal periods. This change has shown the significant influence of hydrologic period and geomorphological features on Rt. Rt, in its turn, has shown significant spatial heterogeneity, depending on location and stretch of the channels. Comparative analyses between simulated and experimental parameters evidenced statistical correlations higher than 0.9. We conclude that the generated Rt scenarios were consistent with other similar studies in the literature. Therefore, they depicted the applicability of the hydrodynamics to the conservation of the Amazonian aquatic ecosystem, as well as its relevance for biochemical and pollutant dispersion studies, which still remain scarce in the literature. Full article

(This article belongs to the Section Urban Water Management)

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31 pages, 9108 KiB

Open AccessEditor’s ChoiceArticle

Emptying Water Towers? Impacts of Future Climate and Glacier Change on River Discharge in the Northern Tien Shan, Central Asia

by Maria Shahgedanova, Muhammad Afzal, Wilfried Hagg, Vassiliy Kapitsa, Nikolay Kasatkin, Elizabeth Mayr, Oleg Rybak, Zarina Saidaliyeva, Igor Severskiy, Zamira Usmanova, Andrew Wade, Natalia Yaitskaya and Dauren Zhumabayev

Water 2020, 12(3), 627; https://doi.org/10.3390/w12030627 - 26 Feb 2020

Cited by 31 | Viewed by 5598

Abstract

Impacts of projected climate and glacier change on river discharge in five glacierized catchments in the northern Tien Shan, Kazakhstan are investigated using a conceptual hydrological model HBV-ETH. Regional climate model PRECIS driven by four different GCM-scenario combinations (HadGEM2.6, HadGEM8.5, A1B using HadCM3Q0 [...] Read more.

Impacts of projected climate and glacier change on river discharge in five glacierized catchments in the northern Tien Shan, Kazakhstan are investigated using a conceptual hydrological model HBV-ETH. Regional climate model PRECIS driven by four different GCM-scenario combinations (HadGEM2.6, HadGEM8.5, A1B using HadCM3Q0 and ECHAM5) is used to develop climate projections. Future changes in glaciation are assessed using the Blatter–Pattyn type higher-order 3D coupled ice flow and mass balance model. All climate scenarios show statistically significant warming in the 21st Century. Neither projects statistically significant change in annual precipitation although HadGEM and HadCM3Q0-driven scenarios show 20–37% reduction in July–August precipitation in 2076–2095 in comparison with 1980–2005. Glaciers are projected to retreat rapidly until the 2050s and stabilize afterwards except under the HadGEM8.5 scenario where retreat continues. Glaciers are projected to lose 38–50% of their volume and 34–39% of their area. Total river discharge in July–August, is projected to decline in catchments with low (2–4%) glacierization by 20–37%. In catchments with high glacierization (16% and over), no significant changes in summer discharge are expected while spring discharge is projected to increase. In catchments with medium glacierization (10–12%), summer discharge is expected to decline under the less aggressive scenarios while flow is sustained under the most aggressive HadGEM8.5 scenario, which generates stronger melt. Full article

(This article belongs to the Special Issue Impacts of Climate Change on Water Resources in Glacierized Regions)

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17 pages, 1607 KiB

Open AccessEditor’s ChoiceReview

Influences of Land-Use Dynamics and Surface Water Systems Interactions on Water-Related Infectious Diseases—A Systematic Review

by Joshua Ntajal, Timo Falkenberg, Thomas Kistemann and Mariele Evers

Water 2020, 12(3), 631; https://doi.org/10.3390/w12030631 - 26 Feb 2020

Cited by 7 | Viewed by 5479

Abstract

Human interactions with surface water systems, through land-use dynamics, can influence the transmission of infectious water-related diseases. As a result, the aim of our study was to explore and examine the state of scientific evidence on the influences of these interactions on water-related [...] Read more.

Human interactions with surface water systems, through land-use dynamics, can influence the transmission of infectious water-related diseases. As a result, the aim of our study was to explore and examine the state of scientific evidence on the influences of these interactions on water-related infectious disease outcomes from a global perspective. A systematic review was conducted, using 54 peer-reviewed research articles published between 1995 and August 2019. The study revealed that there has been an increase in the number of publications since 2009; however, few of these publications (n = 6) made explicit linkages to the topic. It was found that urban and agricultural land-use changes had relatively high adverse impacts on water quality, due to high concentrations of fecal matter, heavy metals, and nutrients in surface water systems. Water systems were found as the common “vehicle” for infectious disease transmission, which in turn had linkages to sanitation and hygiene conditions. The study found explicit linkages between human–surface water interaction patterns and the transmission of water-based disease. However, weak and complex linkages were found between land-use change and the transmission of water-borne disease, due to multiple pathways and the dynamics of the other determinants of the disease. Therefore, further research studies, using interdisciplinary and transdisciplinary approaches to investigate and enhance a deeper understanding of these complexities and linkages among land use, surface water quality, and water-related infectious diseases, is crucial in developing integrated measures for sustainable water quality monitoring and diseases prevention. Full article

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

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15 pages, 1433 KiB

Open AccessEditor’s ChoiceArticle

Water Allocation Using the Bankruptcy Model: A Case Study of the Missouri River

by Heshani Manaweera Wickramage, David C. Roberts and Robert R. Hearne

Water 2020, 12(3), 619; https://doi.org/10.3390/w12030619 - 25 Feb 2020

Cited by 8 | Viewed by 3566

Abstract

This research applies cooperative game theory—specifically, the bankruptcy model—to address conflicts arising from the scarcity of water resources shared by multiple agents. This case study addresses potential outcomes of five allocation rules applied to the apportionment of water between two agents in the [...] Read more.

This research applies cooperative game theory—specifically, the bankruptcy model—to address conflicts arising from the scarcity of water resources shared by multiple agents. This case study addresses potential outcomes of five allocation rules applied to the apportionment of water between two agents in the Missouri River. Currently, there is no interstate compact to apportion Missouri River and frequent disputes between upstream and downstream states occur. Upstream states favor managing reservoir water levels to support reservoir recreation and downstream states want water for the downstream navigation channel. The five allocation rules studied are (1) Proportional Sharing, (2) Constrained Equal Awards, (3) Constrained Equal Losses, (4) Sequential Sharing based on Proportional Sharing, and (5) a proposed Modified Constrained Equal Awards rule. The results of the analysis of apportionment during four dry years in the 2000s show that the best approaches are the proposed Modified Constrained Equal Awards Rule and the Proportional Sharing Rule. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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17 pages, 4792 KiB

Open AccessEditor’s ChoiceArticle

Towards an Assessment of the Ephemeral Gully Erosion Potential in Greece Using Google Earth

by Christos Karydas and Panos Panagos

Water 2020, 12(2), 603; https://doi.org/10.3390/w12020603 - 23 Feb 2020

Cited by 30 | Viewed by 5507

Abstract

Gully erosion may cause considerable soil losses and produce large volumes of sediment. The aim of this study was to perform a preliminary assessment on the presence of ephemeral gullies in Greece by sampling representative cultivated fields in 100 sites randomly distributed throughout [...] Read more.

Gully erosion may cause considerable soil losses and produce large volumes of sediment. The aim of this study was to perform a preliminary assessment on the presence of ephemeral gullies in Greece by sampling representative cultivated fields in 100 sites randomly distributed throughout the country. The almost 30-ha sampling surfaces were examined with visual interpretation of multi-temporal imagery from the online Google Earth for the period 2002–2019. In parallel, rill and sheet erosion signs, land uses, and presence of terraces and other anti-erosion features, were recorded within every sample. One hundred fifty-three ephemeral gullies were identified in total, inside 22 examined agricultural surfaces. The mean length of the gullies was 55.6 m, with an average slope degree of 9.7%. Vineyards showed the largest proportion of gullies followed by olive groves and arable land, while pastures exhibited limited presence of gullies. Spatial clusters of high gully severity were observed in the north and east of the country. In 77% of the surfaces with gullies, there were no terraces, although most of these surfaces were situated in slopes higher than 8%. It was the first time to use visual interpretation with Google Earth image time-series on a country scale producing a gully erosion inventory. Soil conservation practices such as contour farming and terraces could mitigate the risk of gully erosion in agricultural areas. Full article

(This article belongs to the Special Issue The Effect of Hydrology on Soil Erosion)

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19 pages, 6050 KiB

Open AccessEditor’s ChoiceArticle

Transient-Flow Induced Compressed Air Energy Storage (TI-CAES) System towards New Energy Concept

by Mohsen Besharat, Avin Dadfar, Maria Teresa Viseu, Bruno Brunone and Helena M. Ramos

Water 2020, 12(2), 601; https://doi.org/10.3390/w12020601 - 22 Feb 2020

Cited by 9 | Viewed by 5112

Abstract

In recent years, interest has increased in new renewable energy solutions for climate change mitigation and increasing the efficiency and sustainability of water systems. Hydropower still has the biggest share due to its compatibility, reliability and flexibility. This study presents one such technology [...] Read more.

In recent years, interest has increased in new renewable energy solutions for climate change mitigation and increasing the efficiency and sustainability of water systems. Hydropower still has the biggest share due to its compatibility, reliability and flexibility. This study presents one such technology recently examined at Instituto Superior Técnico based on a transient-flow induced compressed air energy storage (TI-CAES) system, which takes advantage of a compressed air vessel (CAV). The CAV can produce extra required pressure head, by compressing air, to be used for either hydropower generation using a water turbine in a gravity system or to be exploited in a pumping system. The results show a controlled behaviour of the system in storing the pressure surge as compressed air inside a vessel. Considerable power values are achieved as well, while the input work is practically neglected. Higher power values are attained for bigger air volumes. The TI-CAES offers an efficient and flexible solution that can be exploited in exiting water systems without putting the system at risk. The induced transients in the compressed air allow a constant outflow discharge characteristic, making the energy storage available in the CAV to be used as a pump storage hydropower solution. Full article

(This article belongs to the Special Issue Environmental Hydraulics Research)

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19 pages, 3701 KiB

Open AccessEditor’s ChoiceArticle

Adsorption of Methylene Blue in Water onto Activated Carbon by Surfactant Modification

by Yu Kuang, Xiaoping Zhang and Shaoqi Zhou

Water 2020, 12(2), 587; https://doi.org/10.3390/w12020587 - 21 Feb 2020

Cited by 374 | Viewed by 20651

Abstract

In this paper, the enhanced adsorption of methylene blue (MB) dye ion on the activated carbon (AC) modified by three surfactants in aqueous solution was researched. Anionic surfactants—sodium lauryl sulfate (SLS) and sodium dodecyl sulfonate (SDS)—and cationic surfactant—hexadecyl trimethyl ammonium bromide (CTAB)—were used [...] Read more.

In this paper, the enhanced adsorption of methylene blue (MB) dye ion on the activated carbon (AC) modified by three surfactants in aqueous solution was researched. Anionic surfactants—sodium lauryl sulfate (SLS) and sodium dodecyl sulfonate (SDS)—and cationic surfactant—hexadecyl trimethyl ammonium bromide (CTAB)—were used for the modification of AC. This work showed that the adsorption performance of cationic dye by activated carbon modified by anionic surfactants (SLS) was significantly improved, whereas the adsorption performance of cationic dye by activated carbon modified by cationic surfactant (CTAB) was reduced. In addition, the effects of initial MB concentration, AC dosage, pH, reaction time, temperature, real water samples, and additive salts on the adsorption were studied. When Na⁺, K⁺, Ca²⁺, NH⁴⁺, and Mg²⁺ were present in the MB dye solution, the effect of these cations was negligible on the adsorption (<5%). The presence of NO^2- improved the adsorption performance significantly, whereas the removal rate of MB was reduced in the presence of competitive cation (Fe²⁺). It was found that the isotherm data had a good correlation with the Langmuir isotherm through analyzing the experimental data by various models. The dynamics of adsorption were better described by the pseudo-second-order model and the adsorption process was endothermic and spontaneous. The results showed that AC modified by anionic surfactant was effective for the adsorption of MB dye in both modeling water and real water. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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15 pages, 1793 KiB

Open AccessEditor’s ChoiceArticle

Predicting the Trend of Dissolved Oxygen Based on the kPCA-RNN Model

by Yi-Fan Zhang, Peter Fitch and Peter J. Thorburn

Water 2020, 12(2), 585; https://doi.org/10.3390/w12020585 - 20 Feb 2020

Cited by 63 | Viewed by 5111

Abstract

Water quality forecasting is increasingly significant for agricultural management and environmental protection. Enormous amounts of water quality data are collected by advanced sensors, which leads to an interest in using data-driven models for predicting trends in water quality. However, the unpredictable background noises [...] Read more.

Water quality forecasting is increasingly significant for agricultural management and environmental protection. Enormous amounts of water quality data are collected by advanced sensors, which leads to an interest in using data-driven models for predicting trends in water quality. However, the unpredictable background noises introduced during water quality monitoring seriously degrade the performance of those models. Meanwhile, artificial neural networks (ANN) with feed-forward architecture lack the capability of maintaining and utilizing the accumulated temporal information, which leads to biased predictions in processing time series data. Hence, we propose a water quality predictive model based on a combination of Kernal Principal Component Analysis (kPCA) and Recurrent Neural Network (RNN) to forecast the trend of dissolved oxygen. Water quality variables are reconstructed based on the kPCA method, which aims to reduce the noise from the raw sensory data and preserve actionable information. With the RNN’s recurrent connections, our model can make use of the previous information in predicting the trend in the future. Data collected from Burnett River, Australia was applied to evaluate our kPCA-RNN model. The kPCA-RNN model achieved

R^{2}

scores up to 0.908, 0.823, and 0.671 for predicting the concentration of dissolved oxygen in the upcoming 1, 2 and 3 hours, respectively. Compared to current data-driven methods like Feed-forward neural network (FFNN), support vector regression (SVR) and general regression neural network (GRNN), the predictive accuracy of the kPCA-RNN model was at least 8%, 17% and 12% better than the comparative models in these three cases. The study demonstrates the effectiveness of the kPAC-RNN modeling technique in predicting water quality variables with noisy sensory data. Full article

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

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15 pages, 8454 KiB

Open AccessEditor’s ChoiceArticle

The Susceptibility of Juvenile American Shad to Rapid Decompression and Fluid Shear Exposure Associated with Simulated Hydroturbine Passage

by Brett D. Pflugrath, Ryan A. Harnish, Briana Rhode, Kristin Engbrecht, Bernardo Beirão, Robert P. Mueller, Erin L. McCann, John R. Stephenson and Alison H. Colotelo

Water 2020, 12(2), 586; https://doi.org/10.3390/w12020586 - 20 Feb 2020

Cited by 7 | Viewed by 3475

Abstract

Throughout many areas of their native range, American shad (Alosa sapidissima) and other Alosine populations are in decline. Though several conditions have influenced these declines, hydropower facilities have had significant negative effects on American shad populations. Hydropower facilities expose ocean-migrating American [...] Read more.

Throughout many areas of their native range, American shad (Alosa sapidissima) and other Alosine populations are in decline. Though several conditions have influenced these declines, hydropower facilities have had significant negative effects on American shad populations. Hydropower facilities expose ocean-migrating American shad to physical stressors during passage through hydropower facilities, including strike, rapid decompression, and fluid shear. In this laboratory-based study, juvenile American shad were exposed separately to rapid decompression and fluid shear to determine their susceptibility to these stressors and develop dose–response models. These dose–response relationships can help guide the development and/or operation of hydropower turbines and facilities to reduce the negative effects to American shad. Relative to other species, juvenile American shad have a high susceptibility to both rapid decompression and fluid shear. Reducing or preventing exposure to these stressors at hydropower facilities may be a potential method to assist in the effort to restore American shad populations. Full article

(This article belongs to the Special Issue Addressing the Environmental Impacts of Hydropower)

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15 pages, 2225 KiB

Open AccessEditor’s ChoiceArticle

Improving the Reliability of Probabilistic Multi-Step-Ahead Flood Forecasting by Fusing Unscented Kalman Filter with Recurrent Neural Network

by Yanlai Zhou, Shenglian Guo, Chong-Yu Xu, Fi-John Chang and Jiabo Yin

Water 2020, 12(2), 578; https://doi.org/10.3390/w12020578 - 20 Feb 2020

Cited by 39 | Viewed by 5111

Abstract

It is fundamentally challenging to quantify the uncertainty of data-driven flood forecasting. This study introduces a general framework for probabilistic flood forecasting conditional on point forecasts. We adopt an unscented Kalman filter (UKF) post-processing technique to model the point forecasts made by a [...] Read more.

It is fundamentally challenging to quantify the uncertainty of data-driven flood forecasting. This study introduces a general framework for probabilistic flood forecasting conditional on point forecasts. We adopt an unscented Kalman filter (UKF) post-processing technique to model the point forecasts made by a recurrent neural network and their corresponding observations. The methodology is tested by using a long-term 6-h timescale inflow series of the Three Gorges Reservoir in China. The main merits of the proposed approach lie in: first, overcoming the under-prediction phenomena in data-driven flood forecasting; second, alleviating the uncertainty encountered in data-driven flood forecasting. Two commonly used artificial neural networks, a recurrent and a static neural network, were used to make the point forecasts. Then the UKF approach driven by the point forecasts demonstrated its competency in increasing the reliability of probabilistic flood forecasts significantly, where predictive distributions encountered in multi-step-ahead flood forecasts were effectively reduced to small ranges. The results demonstrated that the UKF plus recurrent neural network approach could suitably extract the complex non-linear dependence structure between the model’s outputs and observed inflows and overcome the systematic error so that model reliability as well as forecast accuracy for future horizons could be significantly improved. Full article

(This article belongs to the Special Issue Advances in Hydrologic Forecasts and Water Resources Management )

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13 pages, 455 KiB

Open AccessEditor’s ChoiceArticle

Flipped Learning Approach as Educational Innovation in Water Literacy

by Antonio-José Moreno-Guerrero, José-María Romero-Rodríguez, Jesús López-Belmonte and Santiago Alonso-García

Water 2020, 12(2), 574; https://doi.org/10.3390/w12020574 - 20 Feb 2020

Cited by 45 | Viewed by 6896

Abstract

Water literacy has become a fundamental aspect in today’s society, as its conservation, preservation and management is key to ensuring human survival. The purpose of this paper was to analyze the effectiveness of flipped learning methodology on a traditional training practice in water [...] Read more.

Water literacy has become a fundamental aspect in today’s society, as its conservation, preservation and management is key to ensuring human survival. The purpose of this paper was to analyze the effectiveness of flipped learning methodology on a traditional training practice in water literacy at the first level of secondary education. The flipped learning method consisted in providing the contents to the students before the class sessions, encouraging an active learning. A descriptive study was adopted with two experimental groups, two control groups and only post-test. An ad hoc questionnaire was used as an instrument to measure the parameters: Socio-educational, Motivation, Interactions, Autonomy, Collaboration; Deepening of contents; Problem solving, Class time and Ratings. The final sample was composed of 120 students, divided into four groups of 30 students each. The application of the treatment in the experimental groups lasted 10 sessions of 55 min. The results indicate that the use of time in class, the autonomy and the deepening of the contents were the aspects that improved most with the flipped learning approach. However, no significant differences in ratings were found. Finally, the main findings and their implications for water literacy are discussed. Full article

(This article belongs to the Special Issue Water Literacy and Education)

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29 pages, 1851 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances in Real-Time Pluvial Flash Flood Forecasting

by Andre D. L. Zanchetta and Paulin Coulibaly

Water 2020, 12(2), 570; https://doi.org/10.3390/w12020570 - 19 Feb 2020

Cited by 62 | Viewed by 9824

Abstract

Recent years have witnessed considerable developments in multiple fields with the potential to enhance our capability of forecasting pluvial flash floods, one of the most costly environmental hazards in terms of both property damage and loss of life. This work provides a summary [...] Read more.

Recent years have witnessed considerable developments in multiple fields with the potential to enhance our capability of forecasting pluvial flash floods, one of the most costly environmental hazards in terms of both property damage and loss of life. This work provides a summary and description of recent advances related to insights on atmospheric conditions that precede extreme rainfall events, to the development of monitoring systems of relevant hydrometeorological parameters, and to the operational adoption of weather and hydrological models towards the prediction of flash floods. With the exponential increase of available data and computational power, most of the efforts are being directed towards the improvement of multi-source data blending and assimilation techniques, as well as assembling approaches for uncertainty estimation. For urban environments, in which the need for high-resolution simulations demands computationally expensive systems, query-based approaches have been explored for the timely retrieval of pre-simulated flood inundation forecasts. Within the concept of the Internet of Things, the extensive deployment of low-cost sensors opens opportunities from the perspective of denser monitoring capabilities. However, different environmental conditions and uneven distribution of data and resources usually leads to the adoption of site-specific solutions for flash flood forecasting in the context of early warning systems. Full article

(This article belongs to the Special Issue Advances in Flash Flood Forecasting)

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14 pages, 4739 KiB

Open AccessEditor’s ChoiceArticle

When Green Infrastructure Turns Grey: Plant Water Stress as a Consequence of Overdesign in a Tree Trench System

by Min-cheng Tu, Joshua S. Caplan, Sasha W. Eisenman and Bridget M. Wadzuk

Water 2020, 12(2), 573; https://doi.org/10.3390/w12020573 - 19 Feb 2020

Cited by 15 | Viewed by 3772

Abstract

Green infrastructure (GI) systems are often overdesigned. This may be a byproduct of static sizing (e.g., accounting for a design storm’s runoff volume but not exfiltration rates) or may be deliberate (e.g., buffering against performance loss through time). In tree trenches and other [...] Read more.

Green infrastructure (GI) systems are often overdesigned. This may be a byproduct of static sizing (e.g., accounting for a design storm’s runoff volume but not exfiltration rates) or may be deliberate (e.g., buffering against performance loss through time). In tree trenches and other GI systems that require stormwater to accumulate in an infiltration bed before it contacts the planting medium, overdesign could reduce plant water availability significantly. This study investigated the hydrological dynamics and water relations of an overdesigned tree trench system and identified factors contributing to, compounding, and mitigating the risk of plant stress. Water in the infiltration bed reached soil pits only once in three years, with that event occurring during a hydrant release. Moreover, minimal water was retained in soil pits during the event due to the hydraulic properties of the soil media. Through a growing season, one of the two tree types frequently experienced water stress, while the other did so only rarely. These contrasting responses can likely be attributed to roots being largely confined to the soil pits vs. reaching a deeper water source, respectively. Results of this study demonstrate that, in systems where soil pits are embedded in infiltration beds, overdesign can raise the storm size required for water to reach the soil media, reducing plant water availability between storms, and ultimately inducing physiological stress. Full article

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

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26 pages, 4994 KiB

Open AccessEditor’s ChoiceArticle

Hydrogeochemical Characteristics and Assessment of Drinking Water Quality in the Urban Area of Zamora, Mexico

by Claudia Alejandra Reyes-Toscano, Ruth Alfaro-Cuevas-Villanueva, Raúl Cortés-Martínez, Ofelia Morton-Bermea, Elizabeth Hernández-Álvarez, Otoniel Buenrostro-Delgado and Jorge Alejandro Ávila-Olivera

Water 2020, 12(2), 556; https://doi.org/10.3390/w12020556 - 17 Feb 2020

Cited by 52 | Viewed by 5140

Abstract

This work assessed the groundwater hydrogeochemistry and the drinking water quality of 10 wells supplying the urban area of Zamora, Michoacán, Mexico. Two sampling campaigns were conducted in May 2018 (dry season) and November 2018 (wet season) to describe the chemistry of the [...] Read more.

This work assessed the groundwater hydrogeochemistry and the drinking water quality of 10 wells supplying the urban area of Zamora, Michoacán, Mexico. Two sampling campaigns were conducted in May 2018 (dry season) and November 2018 (wet season) to describe the chemistry of the water and its interaction with the rock. Physical and chemical constituents (temperature, pH, electrical conductivity, color, turbidity, solids, total hardness, total alkalinity, chemical and biochemical oxygen demands), major components (Ca²⁺, Mg²⁺, Na⁺, K⁺, SO₄²⁻, PO₄³⁻, HCO₃⁻, CO₃²⁻, Cl⁻, N-NO₃⁻, and N-NH₃), as well as trace elements (As, Fe, Mn, Ba, Al, Sb, Co, V, Cu, Cd, Cr, Ni, Zn, Tl, Pb) were analyzed. Results showed groundwater with a slight tendency to alkalinity. The hydrogeochemical facies observed are Ca²⁺-HCO₃⁻ in all sites. Hydrochemical diagrams indicate immature, cold, non-saline, and uncontaminated water with short residence time. Water–rock interaction predominates. The water in the study area is appropriate for drinking use according to Mexican and international regulations with an excellent quality in 7 wells and good in the other 3. Full article

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

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25 pages, 6912 KiB

Open AccessEditor’s ChoiceArticle

Social Vulnerability Assessment for Flood Risk Analysis

by Laura Tascón-González, Montserrat Ferrer-Julià, Maurici Ruiz and Eduardo García-Meléndez

Water 2020, 12(2), 558; https://doi.org/10.3390/w12020558 - 17 Feb 2020

Cited by 59 | Viewed by 10405

Abstract

This paper proposes a methodology for the analysis of social vulnerability to floods based on the integration and weighting of a range of exposure and resistance (coping capacity) indicators. It focuses on the selection and characteristics of each proposed indicator and the integration [...] Read more.

This paper proposes a methodology for the analysis of social vulnerability to floods based on the integration and weighting of a range of exposure and resistance (coping capacity) indicators. It focuses on the selection and characteristics of each proposed indicator and the integration procedure based on the analytic hierarchy process (AHP) on a large scale. The majority of data used for the calculation of the indicators comes from open public data sources, which allows the replicability of the method in any area where the same data are available. To demonstrate the feasibility of the method, a study case is presented. The flood social vulnerability assessment focuses on the municipality of Ponferrada (Spain), a medium-sized town that has high exposure to floods due to potential breakage of the dam located upstream. A detailed mapping of the social vulnerability index is generated at the urban parcel scale, which shows an affected population of 34,941 inhabitants. The capability of working with such detailed units of analysis for an entire medium-sized town provides a valuable tool to support flood risk planning and management. Full article

(This article belongs to the Special Issue Flood Risk Assessments: Applications and Uncertainties)

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16 pages, 4746 KiB

Open AccessEditor’s ChoiceArticle

An Integral 1-D Eulerian–Lagrangian Method and Its Application to a Hydrodynamic River Network

by Shuai Yuan, Jianzhong Zhou, Dechao Hu and Sipeng Zhu

Water 2020, 12(2), 542; https://doi.org/10.3390/w12020542 - 15 Feb 2020

Cited by 2 | Viewed by 2387

Abstract

It is difficult for a one-dimensional river network hydrodynamic model to manage bifurcations. Traditional methods use simplified junction methods to avoid solving physical equations at bifurcations, which can cause physical distortions and errors. In this article, we propose an algorithm that allows a [...] Read more.

It is difficult for a one-dimensional river network hydrodynamic model to manage bifurcations. Traditional methods use simplified junction methods to avoid solving physical equations at bifurcations, which can cause physical distortions and errors. In this article, we propose an algorithm that allows a Eulerian–Lagrangian method (ELM) to track through bifurcations then solve advective terms, in combination with velocity–pressure couplings, to solve physical equations at bifurcations. The new method discards the simplifications and assumptions used by traditional models and is more complete in theory. We tested the new method with two ideal examples, and the results showed that the new method is time-step independent and grid independent. A simple bifurcation was used to compare this method with MIKE11. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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17 pages, 3186 KiB

Open AccessEditor’s ChoiceArticle

Source and Mobilization Mechanism of Iron, Manganese and Arsenic in Groundwater of Shuangliao City, Northeast China

by Zhihao Zhang, Changlai Xiao, Oluwafemi Adeyeye, Weifei Yang and Xiujuan Liang

Water 2020, 12(2), 534; https://doi.org/10.3390/w12020534 - 14 Feb 2020

Cited by 85 | Viewed by 5859

Abstract

Excessive levels of Fe, Mn and As are the main factors affecting groundwater quality in Songliao plain, northeast China. However, there are few studies on the source and mobilization mechanisms of Fe, Mn and As in the groundwater of Northeastern China. This study [...] Read more.

Excessive levels of Fe, Mn and As are the main factors affecting groundwater quality in Songliao plain, northeast China. However, there are few studies on the source and mobilization mechanisms of Fe, Mn and As in the groundwater of Northeastern China. This study takes Shuangliao city in the middle of Songliao plain as an example, where the source and mobilization mechanisms of iron, manganese and arsenic in groundwater in the study area were analyzed by statistical methods and spatial analysis. The results show that the source of Fe and Mn in the groundwater of the platform is the iron and manganese nodules in the clay layer, while, in the river valley plain, it originates from the soil and the whole aquifer. The TDS, fluctuation in groundwater levels and the residence time are the important factors affecting the content of Fe and Mn in groundwater. The dissolution of iron and manganese minerals causes arsenic adsorbed on them to be released into groundwater. This study provides a basis for the rational utilization of groundwater and protection of people’s health in areas with high iron, manganese and arsenic contents. Full article

(This article belongs to the Special Issue Geochemistry of Water and Sediment)

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23 pages, 6420 KiB

Open AccessEditor’s ChoiceArticle

Effect of Seasonality on the Quantiles Estimation of Maximum Floodwater Levels in a Reservoir and Maximum Outflows

by José Ángel Aranda and R. García-Bartual

Water 2020, 12(2), 519; https://doi.org/10.3390/w12020519 - 13 Feb 2020

Cited by 4 | Viewed by 2270

Abstract

Certain relevant variables for dam safety and downstream safety assessments are analyzed using a stochastic approach. In particular, a method to estimate quantiles of maximum outflow in a dam spillway and maximum water level reached in the reservoir during a flood event is [...] Read more.

Certain relevant variables for dam safety and downstream safety assessments are analyzed using a stochastic approach. In particular, a method to estimate quantiles of maximum outflow in a dam spillway and maximum water level reached in the reservoir during a flood event is presented. The hydrological system analyzed herein is a small mountain catchment in north Spain, whose main river is a tributary of Ebro river. The ancient Foradada dam is located in this catchment. This dam has no gates, so that flood routing operation results from simple consideration of fixed crest spillway hydraulics. In such case, both mentioned variables (maximum outflow and maximum reservoir water level) are basically derived variables that depend on flood hydrograph characteristics and the reservoir’s initial water level. A Monte Carlo approach is performed to generate very large samples of synthetic hydrographs and previous reservoir levels. The use of extreme value copulas allows the ensembles to preserve statistical properties of historical samples and the observed empirical correlations. Apart from the classical approach based on annual periods, the modelling strategy is also applied differentiating two subperiods or seasons (i.e., summer and winter). This allows to quantify the return period distortion introduced when seasonality is ignored in the statistical analysis of the two relevant variables selected for hydrological risk assessment. Results indicate significant deviations for return periods over 125 years. For the analyzed case study, ignoring seasonal statistics and trends, yields to maximum outflows underestimation of 18% for T = 500 years and 29% for T = 1000 years were obtained. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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22 pages, 1982 KiB

Open AccessEditor’s ChoiceArticle

Guidelines for the Use of Unmanned Aerial Systems in Flood Emergency Response

by Gloria Salmoral, Monica Rivas Casado, Manoranjan Muthusamy, David Butler, Prathyush P. Menon and Paul Leinster

Water 2020, 12(2), 521; https://doi.org/10.3390/w12020521 - 13 Feb 2020

Cited by 36 | Viewed by 8210

Abstract

There is increasing interest in using Unmanned Aircraft Systems (UAS) in flood risk management activities including in response to flood events. However, there is little evidence that they are used in a structured and strategic manner to best effect. An effective response to [...] Read more.

There is increasing interest in using Unmanned Aircraft Systems (UAS) in flood risk management activities including in response to flood events. However, there is little evidence that they are used in a structured and strategic manner to best effect. An effective response to flooding is essential if lives are to be saved and suffering alleviated. This study evaluates how UAS can be used in the preparation for and response to flood emergencies and develops guidelines for their deployment before, during and after a flood event. A comprehensive literature review and interviews, with people with practical experience of flood risk management, compared the current organizational and operational structures for flood emergency response in both England and India, and developed a deployment analysis matrix of existing UAS applications. An online survey was carried out in England to assess how the technology could be further developed to meet flood emergency response needs. The deployment analysis matrix has the potential to be translated into an Indian context and other countries. Those organizations responsible for overseeing flood risk management activities including the response to flooding events will have to keep abreast of the rapid technological advances in UAS if they are to be used to best effect. Full article

(This article belongs to the Special Issue Flood Risk and Resilience)

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16 pages, 4175 KiB

Open AccessEditor’s ChoiceArticle

Modeling of River Channel Shading as a Factor for Changes in Hydromorphological Conditions of Small Lowland Rivers

by Tomasz Kałuża, Mariusz Sojka, Rafał Wróżyński, Joanna Jaskuła, Stanisław Zaborowski and Mateusz Hämmerling

Water 2020, 12(2), 527; https://doi.org/10.3390/w12020527 - 13 Feb 2020

Cited by 13 | Viewed by 3305

Abstract

The ecological water quality in rivers and streams is influenced both by the morphological factors (within the watercourse channel and by the dynamic factors associated with flow), as well as biological factors (connected with the flora and fauna characteristic of its specific area). [...] Read more.

The ecological water quality in rivers and streams is influenced both by the morphological factors (within the watercourse channel and by the dynamic factors associated with flow), as well as biological factors (connected with the flora and fauna characteristic of its specific area). This paper presents an analysis of the effect of river channel shading by trees and shrubs on hydromorphological changes in a selected reach of the Wełna River, Poland. The analysis was conducted on two adjacent cross-sections (one in a reach lined with trees, the other in an open area with no tree or shrub vegetation). Data were collected during field surveys in the years 2014 and 2019. According to the Water Framework Directive, the Wełna River represents a watercourse with small and average-sized watershed areas, with sand being the dominant substrate of the river bottom. Flow volume, distributions of velocity in the sections, as well as substrate grain-size characteristics and river bottom morphology, were determined based on field measurements. In the study, the leaf area index (LAI) of vegetation was measured in the reach lined with trees, while the number and species composition of macrophytes were determined in the investigated river reaches. Moreover, a digital surface model (DSM) and Geoinformation Information System GIS tools were used to illustrate variability in shading within the tree-lined reach. The DSM model was based on Light Detection and Ranging (LIDAR) data. The results of this study enable us to establish the relationship between river shading by vegetation covering the bank zone, and changes in hydromorphological parameters of the river channel. Full article

(This article belongs to the Special Issue The Application of Hydraulic and Sediment Transport Models in Fluvial Geomorphology)

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33 pages, 2256 KiB

Open AccessFeature PaperEditor’s ChoiceReview

It Is Not Easy Being Green: Recognizing Unintended Consequences of Green Stormwater Infrastructure

by Vinicius J. Taguchi, Peter T. Weiss, John S. Gulliver, Mira R. Klein, Raymond M. Hozalski, Lawrence A. Baker, Jacques C. Finlay, Bonnie L. Keeler and John L. Nieber

Water 2020, 12(2), 522; https://doi.org/10.3390/w12020522 - 13 Feb 2020

Cited by 73 | Viewed by 17994

Abstract

Green infrastructure designed to address urban drainage and water quality issues is often deployed without full knowledge of potential unintended social, ecological, and human health consequences. Though understood in their respective fields of study, these diverse impacts are seldom discussed together in a [...] Read more.

Green infrastructure designed to address urban drainage and water quality issues is often deployed without full knowledge of potential unintended social, ecological, and human health consequences. Though understood in their respective fields of study, these diverse impacts are seldom discussed together in a format understood by a broader audience. This paper takes a first step in addressing that gap by exploring tradeoffs associated with green infrastructure practices that manage urban stormwater including urban trees, stormwater ponds, filtration, infiltration, rain gardens, and green roofs. Each green infrastructure practice type performs best under specific conditions and when targeting specific goals, but regular inspections, maintenance, and monitoring are necessary for any green stormwater infrastructure (GSI) practice to succeed. We review how each of the above practices is intended to function and how they could malfunction in order to improve how green stormwater infrastructure is designed, constructed, monitored, and maintained. Our proposed decision-making framework, using both biophysical (biological and physical) science and social science, could lead to GSI projects that are effective, cost efficient, and just. Full article

(This article belongs to the Special Issue Urban Water Policy and Planning Strategies for an Uncertain Water Future)

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23 pages, 8851 KiB

Open AccessEditor’s ChoiceArticle

Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices

by Teresita Canchala, Wilmar Loaiza Cerón, Félix Francés, Yesid Carvajal-Escobar, Rita Valéria Andreoli, Mary Toshie Kayano, Wilfredo Alfonso-Morales, Eduardo Caicedo-Bravo and Rodrigo Augusto Ferreira de Souza

Water 2020, 12(2), 526; https://doi.org/10.3390/w12020526 - 13 Feb 2020

Cited by 25 | Viewed by 4753

Abstract

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows [...] Read more.

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Niño/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall’s tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basin, with an explained variance of around 80%. The correlation analyses between the PC1s of the ARB and PRB, and the climate indices showed significant positive (negative) high correlations with PRP, CJ, and Southern Oscillation Index (SOI) (ENSO indices). The wavelet coherence analysis showed significant coherencies between ENSO and ARB: at interannual (2–7 years) and decadal scale (8–14), preferably with the sea surface temperature (SST) in the east and west Tropical Pacific Ocean (TPO). For PRB with the SST in the central and western regions of the TPO in the interannual (4–8 years) and decadal (8–14 years) scales, the decreases (increases) in streamflow precede the El Niño (La Niña) events. These results indicate multiscale relations between the basins’ streamflow and climate phenomena not documented in previous works, relevant to forecast the extreme flow events in the Colombian Pacific rivers and for planning and implementing strategies for the sustainable use of water resources in the basins studied. Full article

(This article belongs to the Special Issue Assessment of Spatial and Temporal Variability of Water Resources)

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11 pages, 1659 KiB

Open AccessEditor’s ChoiceArticle

Metagenomics Uncovers a Core SAR11 Population in Brackish Surface Waters of the Baltic Sea

by Poorna Weerarathna Vidanage, Seok-Oh Ko and Seungdae Oh

Water 2020, 12(2), 501; https://doi.org/10.3390/w12020501 - 12 Feb 2020

Cited by 5 | Viewed by 2768

Abstract

The Baltic Sea represents one of the largest brackish ecosystems where various environmental factors control dynamic seasonal shifts in the structure, diversity, and function of the planktonic microbial communities. In this study, despite seasonal fluctuations, several bacterial populations (<2% of the total OTUs) [...] Read more.

The Baltic Sea represents one of the largest brackish ecosystems where various environmental factors control dynamic seasonal shifts in the structure, diversity, and function of the planktonic microbial communities. In this study, despite seasonal fluctuations, several bacterial populations (<2% of the total OTUs) that are highly dominant (25% of relative abundance) and highly frequently occurring (>85% of occurrence) over four seasons were identified. Mathematical models using occurrence frequency and relative abundance data were able to describe community assembly persisting over time. Further, this work uncovered one of the core bacterial populations phylogenetically affiliated to SAR11 subclade IIIa. The analysis of the hypervariable region of 16S rRNA gene and single copy housekeeping genes recovered from metagenomic datasets suggested that the population was unexpectedly evolutionarily closely related to those inhabiting a mesosaline lacustrine ecosystem rather than other marine/coastal members. Our metagenomic results further revealed that the newly-identified population was the major driver facilitating the seasonal shifts in the overall community structure over the brackish waters of the Baltic Sea. The core community uncovered in this study supports the presence of a brackish water microbiome distinguishable from other marine and freshwater counterparts and will be a useful sentinel for monitoring local/global environmental changes posed on brackish surface waters. Full article

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30 pages, 1778 KiB

Open AccessEditor’s ChoiceReview

Role of Nanomaterials in the Treatment of Wastewater: A Review

by Asim Ali Yaqoob, Tabassum Parveen, Khalid Umar and Mohamad Nasir Mohamad Ibrahim

Water 2020, 12(2), 495; https://doi.org/10.3390/w12020495 - 12 Feb 2020

Cited by 471 | Viewed by 44048

Abstract

Water is an essential part of life and its availability is important for all living creatures. On the other side, the world is suffering from a major problem of drinking water. There are several gases, microorganisms and other toxins (chemicals and heavy metals) [...] Read more.

Water is an essential part of life and its availability is important for all living creatures. On the other side, the world is suffering from a major problem of drinking water. There are several gases, microorganisms and other toxins (chemicals and heavy metals) added into water during rain, flowing water, etc. which is responsible for water pollution. This review article describes various applications of nanomaterial in removing different types of impurities from polluted water. There are various kinds of nanomaterials, which carried huge potential to treat polluted water (containing metal toxin substance, different organic and inorganic impurities) very effectively due to their unique properties like greater surface area, able to work at low concentration, etc. The nanostructured catalytic membranes, nanosorbents and nanophotocatalyst based approaches to remove pollutants from wastewater are eco-friendly and efficient, but they require more energy, more investment in order to purify the wastewater. There are many challenges and issues of wastewater treatment. Some precautions are also required to keep away from ecological and health issues. New modern equipment for wastewater treatment should be flexible, low cost and efficient for the commercialization purpose. Full article

(This article belongs to the Special Issue Water Treatment with New Nanomaterials)

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34 pages, 15236 KiB

Open AccessEditor’s ChoiceArticle

Performance Evaluation of Bias Correction Methods for Climate Change Monthly Precipitation Projections over Costa Rica

by Maikel Mendez, Ben Maathuis, David Hein-Griggs and Luis-Fernando Alvarado-Gamboa

Water 2020, 12(2), 482; https://doi.org/10.3390/w12020482 - 11 Feb 2020

Cited by 117 | Viewed by 10228

Abstract

Six bias correction (BC) methods; delta-method (DT), linear scaling (LS), power transformation of precipitation (PTR), empirical quantile mapping (EQM), gamma quantile mapping (GQM) and gamma-pareto quantile mapping (GPQM) were applied to adjust the biases of historical monthly precipitation outputs from five General Circulation [...] Read more.

Six bias correction (BC) methods; delta-method (DT), linear scaling (LS), power transformation of precipitation (PTR), empirical quantile mapping (EQM), gamma quantile mapping (GQM) and gamma-pareto quantile mapping (GPQM) were applied to adjust the biases of historical monthly precipitation outputs from five General Circulation Models (GCMs) dynamically downscaled by two Regional Climate Models (RCMs) for a total of seven different GCM-RCM pairs over Costa Rica. High-resolution gridded precipitation observations were used for the control period 1951–1980 and validated over the period 1981–1995. Results show that considerable biases exist between uncorrected GCM-RCM outputs and observations, which largely depend on GCM-RCM pair, seasonality, climatic region and spatial resolution. After the application of bias correction, substantial biases reductions and comparable performances among most BC methods were observed for most GCM-RCM pairs; with EQM and DT marginally outperforming the remaining methods. Consequently, EQM and DT were selectively applied to correct the biases of precipitation projections from each individual GCM-RCM pair for a near-future (2011–2040), mid-future (2041–2070) and far-future (2071–2100) period under Representative Concentration Pathways (RCPs) 2.6, 4.5 and 8.5 using the control period 1961–1990. Results from the bias-corrected future ensemble-mean anticipate a marked decreasing trend in precipitation from near to far-future periods during the dry season (December, January, February (DJF) and March, April, May (MAM)) for RCP4.5 and 8.5; with pronounced drier conditions for those climatic regions draining towards the Pacific Ocean. In contrast, mostly wetter conditions are expected during the dry season under RCP2.6, particularly for the Caribbean region. In most of the country, the greatest decrease in precipitation is projected at the beginning of the rainy season (June, July, August (JJA)) for the far-future period under RCP8.5, except for the Caribbean region where mostly wetter conditions are anticipated. Regardless of future period, slight increases in precipitation with higher radiative forcing are expected for SON excluding the Caribbean region, where precipitation is likely to increase with increasing radiative forcing and future period. This study demonstrates that bias correction should be considered before direct application of GCM-RCM precipitation projections over complex territories such as Costa Rica. Full article

(This article belongs to the Section Hydrology)

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23 pages, 1538 KiB

Open AccessEditor’s ChoiceArticle

Environmental Sustainability Assessment of a New Sewage Treatment Plant in China Based on Infrastructure Construction and Operation Phases Emergy Analysis

by Junxue Zhang and Lin Ma

Water 2020, 12(2), 484; https://doi.org/10.3390/w12020484 - 11 Feb 2020

Cited by 36 | Viewed by 12060

Abstract

Due to excessive resource consumption and pressing environmental issues of the sewage treatment industry, there is extensive attention in China. Given the unique craft production process in the sewage treatment system, a series of integral emergy indicators have been used to evaluate the [...] Read more.

Due to excessive resource consumption and pressing environmental issues of the sewage treatment industry, there is extensive attention in China. Given the unique craft production process in the sewage treatment system, a series of integral emergy indicators have been used to evaluate the environmental sustainability based on infrastructure construction and operation stage emergy analysis. Taking a new typical sewage treatment plant as an example, this paper performed a case study. The results illustrate that (1) the infrastructure construction process emergy (approximate 92.6%) is more critical than sewage treatment process emergy; (2) nonrenewable resource is the primary factor for the emergy analysis, followed by energy (23.5%) and purchased supply (7%); (3) cement, steel, and gravel have dominant impacts on the nonrenewable resource emergy; (4) the emergy sustainability index is 0.001101, which displays weak environmental sustainability; (5) the unit emergy value (UEV) of the new sewage treatment plant is 3.40 × 10¹² sej/m³; (6) sensitivity analysis results of the hypothesis demonstrate that nonrenewable resources have significant fluctuations (6.903%) while, for the indicators, emergy sustainability index (ESI) (4.8072%) has the most significant impact; and (7) wastewater is a major contributor. In light of comprehensive discussions, two positive measures are proposed in order to ameliorate the environmental sustainability. Full article

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

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15 pages, 1528 KiB

Open AccessEditor’s ChoiceArticle

Performance Behavior of Participatory Water Institutions in Eastern India: A Study through Structural Equation Modelling

by Nicky Johnson, Vasant P. Gandhi and Dinesh Jain

Water 2020, 12(2), 485; https://doi.org/10.3390/w12020485 - 11 Feb 2020

Cited by 2 | Viewed by 2949

Abstract

The paper examines the nature and performance of participatory water institutions in eastern India using structural equation modelling. There is a crisis in the management of water in India, and this is often not about having too little water but about managing it [...] Read more.

The paper examines the nature and performance of participatory water institutions in eastern India using structural equation modelling. There is a crisis in the management of water in India, and this is often not about having too little water but about managing it poorly. It is now being widely recognized that engineering structures and solutions are not enough, and having effective water institutions is critical. These are urgently needed in eastern India for helping lift the region out of low incomes and poverty. However, creating good institutions is complex, and in this context, the fundamentals of new institutional economics, and management governance theory have suggested the importance of a number of key factors including five institutional features and eight rationalities. Based on this, a study was conducted in eastern India, sampling from the states of Assam and Bihar, covering 510 farm households across 51 water institutions. In order to understand and map the relationship and pathways across these key factors, a structural equation model is hypothesized. In the model, the five institutional features are considered determinants of the eight rationalities, and the rationalities are considered determinants of four performance goals. The performance on the goals determines the overall performance/success of the institution. Besides this, the institutional features and rationalities can also directly influence performance on the goals and the overall performance. The model is tested with data from the survey and different pathways that are robust are identified. The results can provide useful insights into the interlinkages and pathways of institutional behavior and can help policy and institution design for delivering more robust performance. The results show that one of the most important factors determining overall performance/success is technical rationality, and this deserves great attention. It includes technical expertise, sound location and quality of structures and equipment, and good maintenance. However, success is also strongly linked to performance on production/income goals, equity, and environment goals. These are, in turn, strongly related to achievement of economic, social, technical, and organizational rationalities, which call for attention to economic aspects such as crop choice and marketing, besides social aspects such as inclusion of women and poorer social groups, and organizational aspects such as member involvement and regular meetings. Further, the institutional features of clear objectives, good interactions, adaptive, correct scale, and compliance are important for achievement of almost all rationalities through various pathways, and should be strongly focused on in all the institutions. 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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14 pages, 1273 KiB

Open AccessEditor’s ChoiceReview

An Engineering Perspective of Water Sharing Issues in Pakistan

by Muhammad Atiq Ur Rehman Tariq, Nick van de Giesen, Shahmir Janjua, Muhammad Laiq Ur Rahman Shahid and Rashid Farooq

Water 2020, 12(2), 477; https://doi.org/10.3390/w12020477 - 11 Feb 2020

Cited by 22 | Viewed by 12829

Abstract

Water sharing within the states/provinces of a country and cross-border is unavoidable. Conflicts between the sharing entities might turn more severe due to additional dependency on water, growing population, and reduced availability as a result of climate change at many locations. Pakistan, being [...] Read more.

Water sharing within the states/provinces of a country and cross-border is unavoidable. Conflicts between the sharing entities might turn more severe due to additional dependency on water, growing population, and reduced availability as a result of climate change at many locations. Pakistan, being an agricultural country, is severely water stressed and heading toward a worsening situation in the near future. Pakistan is heading toward water scarcity as water availability in the Indus basin is becoming critical. Being a downstream riparian of India and Afghanistan in the Indus basin, water availability depends on the releases of water from both countries. The Indus Water Treaty is governing the water distribution rights between India and Pakistan. However, there exists no proper agreement between Pakistan and Afghanistan and the construction of new dams on the Kabul River is another threat to water availability to Pakistan. Correct implementation of the Indus Water Treaty with India is required, together with an effective agreement with Afghanistan about the water sharing. In addition to water shortage, poor management of water resources, inequitable sharing of water, lack of a systematic approach, old-fashioned irrigation practices, and growing agricultural products with large water footprints are all exacerbating the problem. The water shortage is now increasingly countered by the use of groundwater. This sudden high extraction of groundwater is causing depletion of the groundwater table and groundwater quality issues. This water shortage is exacerbating the provincial conflicts over water, such as those between Punjab and Sindh provinces. At one end, a uniform nationwide water allocation policy is required. At the same time, modern irrigation techniques and low-water-footprint agricultural products should be promoted. A fair water-pricing mechanism of surface water and groundwater could be an effective measure, whereas a strict policy on groundwater usage is equally important. Political will and determination to address the water issues are required. The solutions must be based on transparency and equity, by using engineering approaches, combined with comprehensive social support. To develop a comprehensive water strategy, a dedicated technopolitical institute to strengthen the capabilities of nationwide expertise and address the issues on a regular basis is required to overcome the complex and multidimensional water-related problems of the country. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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16 pages, 8073 KiB

Open AccessEditor’s ChoiceArticle

Drought Trends in Balochistan

by Falak Naz, Ghulam Hussain Dars, Kamran Ansari, Shoaib Jamro and Nir Y. Krakauer

Water 2020, 12(2), 470; https://doi.org/10.3390/w12020470 - 10 Feb 2020

Cited by 53 | Viewed by 13129

Abstract

Drought is a severe threat, especially in the arid regions of Pakistan, such as the Balochistan Province. The aim of this study is to analyze drought trends in Balochistan using Standard Precipitation Index (SPI) at the 3-month accumulation timescale. The monthly rainfall data [...] Read more.

Drought is a severe threat, especially in the arid regions of Pakistan, such as the Balochistan Province. The aim of this study is to analyze drought trends in Balochistan using Standard Precipitation Index (SPI) at the 3-month accumulation timescale. The monthly rainfall data of 10 stations were collected from the Pakistan Meteorological Department (PMD) for 37 years (1980–2017). Drought trends were analyzed at each station using the Mann-Kendall test. The SPI identified extreme drought events in 1996, 2001, 2002, 2004, 2009, and 2014. Barkhan was the station that most frequently experienced extreme to severe drought events, as defined using SPI. A statistically significant decreasing precipitation trend was found in four stations (Dalbandin, Jiwani, Quetta, and Zhob). The analysis of drought characteristics showed Barkhan faced the most prolonged drought, of 22 months from 1999 to 2001. The findings from the present study can give guidance on how strategies of water management should be adjusted based on the changing patterns of droughts in the Balochistan Province. Full article

(This article belongs to the Special Issue Effects of Climate Change on Water Resources)

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16 pages, 7377 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Mapping of Groundwater Potential Zones in Crystalline Terrain Using Remote Sensing, GIS Techniques, and Multicriteria Data Analysis (Case of the Ighrem Region, Western Anti-Atlas, Morocco)

by Khalid Benjmel, Fouad Amraoui, Said Boutaleb, Mohammed Ouchchen, Amine Tahiri and Amine Touab

Water 2020, 12(2), 471; https://doi.org/10.3390/w12020471 - 10 Feb 2020

Cited by 120 | Viewed by 7790

Abstract

This research work is intended as a contribution to the development of a multicriteria methodology, combining several factors to control the availability of groundwater resources, in order to optimize the choice of location of future drilling and increase the chances to take water [...] Read more.

This research work is intended as a contribution to the development of a multicriteria methodology, combining several factors to control the availability of groundwater resources, in order to optimize the choice of location of future drilling and increase the chances to take water from productive structures which will satisfy the ever-increasing water demand of local population (Arghen basin in the Western Anti-Atlas chain of Morocco). The geographic information system is used to develop thematic maps describing the geometry and the hydrodynamic functioning of the aquifer. In this study, 11 factors including geology, topography, and hydrology, influencing the distribution of water resources were used. Based on the Analytical Hierarchy Process (AHP) model, GIS, and remote sensing, the study mapped and classified areas according to their hydrogeological potential. The favorable potential sectors cover 17% of the total area of the basin. The medium potential sectors account for 64%, while the unfavorable areas cover 18% of the basin area. The groundwater potential map of the study area has been validated by comparing with data from 159 boreholes scattered throughout the basin. Full article

(This article belongs to the Special Issue Groundwater Resilience to Climate Change and High Pressure)

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23 pages, 2679 KiB

Open AccessEditor’s ChoiceArticle

Modeling of Future Extreme Storm Surges at the NW Mediterranean Coast (Spain)

by Jue Lin-Ye, Manuel García-León, Vicente Gràcia, María Isabel Ortego, Piero Lionello, Dario Conte, Begoña Pérez-Gómez and Agustín Sánchez-Arcilla

Water 2020, 12(2), 472; https://doi.org/10.3390/w12020472 - 10 Feb 2020

Cited by 19 | Viewed by 3635

Abstract

Storm surges are one of the main drivers for extreme flooding at the coastal areas. Such events can be characterized with the maximum level in an extreme storm surge event (surge peak), as well as the duration of the event. Surge projections come [...] Read more.

Storm surges are one of the main drivers for extreme flooding at the coastal areas. Such events can be characterized with the maximum level in an extreme storm surge event (surge peak), as well as the duration of the event. Surge projections come from a barotropic model for the 1950–2100 period, under a severe climate change scenario (RCP 8.5) at the northeastern Spanish coast. The relationship of extreme storm surges to three large-scale climate patterns was assessed: North Atlantic Oscillation (

N A O

), East Atlantic Pattern (

E A W R

), and Scandinavian Pattern (

S C

). The statistical model was built using two different strategies. In Strategy #1, the joint probability density was characterized by a moving-average series of stationary Archimedean copula, whereas in Strategy #2, the joint probability density was characterized by a non-stationary probit copula. The parameters of the marginal distribution and the copula were defined with generalized additive models. The analysis showed that the mean values of surge peak and event duration were constant and were independent of the proposed climate patterns. However, the values of

N A O

and

S C

influenced the threshold and the storminess of extreme events. According to Strategy #1, the variance of the surge peak and event duration increased with a fast shift of negative

S C

and a positive

N A O

, respectively. Alternatively, Strategy #2 showed that the variance of the surge peak increased with a positive

E A W R

. Both strategies coincided in that the joint dependence of the maximum surge level and the duration of extreme surges ranged from low to medium degree. Its mean value was stationary, and its variability was linked to the geographical location. Finally, Strategy #2 helped determine that this dependence increased with negative

N A O

. Full article

(This article belongs to the Special Issue Effect of Climate Change on Coastal Hydrodynamics)

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13 pages, 2309 KiB

Open AccessEditor’s ChoiceArticle

Eco-Efficiency of End-of-Pipe Systems: An Extended Environmental Cost Efficiency Framework for Wastewater Treatment

by Xinyue Zhao, Chaofan Zhang and Shunwen Bai

Water 2020, 12(2), 454; https://doi.org/10.3390/w12020454 - 8 Feb 2020

Cited by 7 | Viewed by 2644

Abstract

As a method for eco-efficiency analysis, environmental cost efficiency (ECE) indicators have been proposed for the end-of-pipe (EOP) systems that referred to the techniques achieving environmental benefit under economic cost. The wastewater treatment plant (WWTP) belongs to the EOP systems; however, few studies [...] Read more.

As a method for eco-efficiency analysis, environmental cost efficiency (ECE) indicators have been proposed for the end-of-pipe (EOP) systems that referred to the techniques achieving environmental benefit under economic cost. The wastewater treatment plant (WWTP) belongs to the EOP systems; however, few studies used the ECE indicators for the sustainability evaluation. Here, this study first proposed the following processes that had been excluded in the current ECE framework and thus limited the potential application in WWTP: (1) the direct impact of wastewater on receiving water, (2) the migration and transformation of water pollutants affected by the self-purification mechanisms of receiving water. To address the aforementioned processes, this study extended the framework of ECE indicators by means of incorporating the potential growth of microorganisms as the characterization state and integrating the water quality models with the characterization models. To investigate the applicability, a full-scale WWTP was selected as the study case and the eco-efficiency of the increasing levels of sewage treatment was evaluated. The case outcome showed that, with the extended ECE indicators, the analysis of eco-efficiency could be directly related to the specific locations and could determine the specific distance ranges within which the scenarios changing were considered efficient. Moreover, the eco-efficiency could be investigated under more concrete and flexible situations because the extended framework of ECE indicators was able to include more information, such as different types of receiving water or different environmental conditions of certain water body. Full article

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

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7 pages, 620 KiB

Open AccessEditor’s ChoiceArticle

The Occurrence of Antibiotic Resistance Genes in an Urban River in Nepal

by Ocean Thakali, Sarmila Tandukar, John P. Brooks, Samendra P. Sherchan, Jeevan B. Sherchand and Eiji Haramoto

Water 2020, 12(2), 450; https://doi.org/10.3390/w12020450 - 7 Feb 2020

Cited by 21 | Viewed by 5337

Abstract

Urban rivers affected by anthropogenic activities can act as reservoirs of antibiotic resistance genes (ARGs). This study aimed to describe the occurrence of selected ARGs (bla_TEM, ermF, mecA, and tetA) and a class 1 integron (intI1 [...] Read more.

Urban rivers affected by anthropogenic activities can act as reservoirs of antibiotic resistance genes (ARGs). This study aimed to describe the occurrence of selected ARGs (bla_TEM, ermF, mecA, and tetA) and a class 1 integron (intI1) in an urban river in Nepal. A total of 18 water samples were collected periodically from upstream, midstream, and downstream sites along the Bagmati River over a 1-year period. All ARGs except mecA and intI1 were consistently detected by a quantitative polymerase chain reaction in the midstream and downstream sites, with concentrations ranging from 3.1 to 7.8 log copies/mL. ARG abundance was significantly lower at the upstream site (p < 0.05), reflecting the impact of anthropogenic activities on increasing concentrations of ARGs at midstream and downstream sites. Our findings demonstrate the presence of clinically relevant ARGs in the urban river water of Nepal, suggesting a need for mitigating strategies to prevent the spread of antibiotic resistance in the environment. Full article

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

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13 pages, 6356 KiB

Open AccessEditor’s ChoiceArticle

Adsorption Properties of Magnetic Magnetite Nanoparticle for Coexistent Cr(VI) and Cu(II) in Mixed Solution

by Jin Zhang, Shuang Lin, Meiling Han, Qing Su, Lianqiu Xia and Zhaocong Hui

Water 2020, 12(2), 446; https://doi.org/10.3390/w12020446 - 7 Feb 2020

Cited by 79 | Viewed by 5009

Abstract

The adsorption properties of coexistent Cr(VI) and Cu(II) in mixed solution on magnetic magnetite (Fe₃O₄) nanoparticle were studied in batch experiments. The influences of various factors, such as pH, adsorbent dose, temperature, initial concentration of metal ions, and coexisting [...] Read more.

The adsorption properties of coexistent Cr(VI) and Cu(II) in mixed solution on magnetic magnetite (Fe₃O₄) nanoparticle were studied in batch experiments. The influences of various factors, such as pH, adsorbent dose, temperature, initial concentration of metal ions, and coexisting ions in water were investigated. At the same time, the adsorption kinetics and adsorption isotherms were studied. The mechanism of adsorption for Cr(VI) and Cu(II) was investigated through the study of surface properties of Fe₃O₄, the presence of ions, and the influence of pH and zeta potential. The results indicate that pH has an influence on adsorption for Cr(VI) and Cu(II), and the optimal pH value for Cr(VI) and Cu(II) adsorption is 4.0. The adsorption efficiency increased with the increase of the adsorbent dose. Temperature under experimental design had no obvious effect. With 2.0 g/dm³ Fe₃O₄, the maximum adsorption capacity for Cr(VI) and Cu(II) reached 8.67 mg/g and 18.61 mg/g in mixed solution of 80 mg/dm³ Cr(VI) and Cu(II), respectively. Phosphorus had some influence on the adsorption for Cr(VI), and other coexisting anions and cations had no influence on the adsorption for Cr(VI) and Cu(II). The adsorption data for Cr(VI) and Cu(II) were nicely fit to the Langmuir adsorption equation and the pseudo-second-order model. As a multifunctional material, nano-Fe₃O₄ exhibited good adsorption performance for coexistent Cr(VI) and Cu(II) and could easily be separated and recovered under magnetic field. Full article

(This article belongs to the Special Issue Removal of Heavy Metals from Wastewater)

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21 pages, 3563 KiB

Open AccessEditor’s ChoiceArticle

The Applicability of LSTM-KNN Model for Real-Time Flood Forecasting in Different Climate Zones in China

by Moyang Liu, Yingchun Huang, Zhijia Li, Bingxing Tong, Zhentao Liu, Mingkun Sun, Feiqing Jiang and Hanchen Zhang

Water 2020, 12(2), 440; https://doi.org/10.3390/w12020440 - 6 Feb 2020

Cited by 72 | Viewed by 7093

Abstract

Flow forecasting is an essential topic for flood prevention and mitigation. This study utilizes a data-driven approach, the Long Short-Term Memory neural network (LSTM), to simulate rainfall–runoff relationships for catchments with different climate conditions. The LSTM method presented was tested in three catchments [...] Read more.

Flow forecasting is an essential topic for flood prevention and mitigation. This study utilizes a data-driven approach, the Long Short-Term Memory neural network (LSTM), to simulate rainfall–runoff relationships for catchments with different climate conditions. The LSTM method presented was tested in three catchments with distinct climate zones in China. The recurrent neural network (RNN) was adopted for comparison to verify the superiority of the LSTM model in terms of time series prediction problems. The results of LSTM were also compared with a widely used process-based model, the Xinanjiang model (XAJ), as a benchmark to test the applicability of this novel method. The results suggest that LSTM could provide comparable quality predictions as the XAJ model and can be considered an efficient hydrology modeling approach. A real-time forecasting approach coupled with the k-nearest neighbor (KNN) algorithm as an updating method was proposed in this study to generalize the plausibility of the LSTM method for flood forecasting in a decision support system. We compared the simulation results of the LSTM and the LSTM-KNN model, which demonstrated the effectiveness of the LSTM-KNN model in the study areas and underscored the potential of the proposed model for real-time flood forecasting. Full article

(This article belongs to the Section Hydrology)

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14 pages, 2360 KiB

Open AccessEditor’s ChoiceArticle

Heavy Metals Distribution, Sources, and Ecological Risk Assessment in Huixian Wetland, South China

by Liangliang Huang, Saeed Rad, Li Xu, Liangying Gui, Xiaohong Song, Yanhong Li, Zhiqiang Wu and Zhongbing Chen

Water 2020, 12(2), 431; https://doi.org/10.3390/w12020431 - 6 Feb 2020

Cited by 98 | Viewed by 5871

Abstract

This research has focused on the source identification, concentration, and ecological risk assessment of eight heavy metals in the largest karst wetland (Huixian) of south China. Numerous samples from superficial soil and sediment within ten representative landuse types were collected and examined, and [...] Read more.

This research has focused on the source identification, concentration, and ecological risk assessment of eight heavy metals in the largest karst wetland (Huixian) of south China. Numerous samples from superficial soil and sediment within ten representative landuse types were collected and examined, and the results were analyzed using multiple methods. Single pollution index (Pi) results were underpinned by the Geoaccumulation index (I_geo) method, in which Cd was observed as the priority pollutant with the highest contamination degree in this area. As for the most polluted landuse type, via applying Nemerow’s synthetical contamination index (P_N) and Potential ecological risk index (RI), the river and rape field posed the highest ecological risks, while moderate for the rest. To quantify the drivers of the contaminants, a principal component analysis (PCA) was carried out and weathering of the watershed’s parent carbonate rocks was found to be the main possible origin, followed by anthropogenic sources induced by agricultural fertilizer. Considering the impacts of these potentially toxic elements on public health, the results of this study are essential to take preventive actions for environmental protection and sustainable development in the region. Full article

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

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16 pages, 3303 KiB

Open AccessEditor’s ChoiceArticle

Forcing for a Cascaded Lattice Boltzmann Shallow Water Model

by Sara Venturi, Silvia Di Francesco, Martin Geier and Piergiorgio Manciola

Water 2020, 12(2), 439; https://doi.org/10.3390/w12020439 - 6 Feb 2020

Cited by 7 | Viewed by 2999

Abstract

This work compares three forcing schemes for a recently introduced cascaded lattice Boltzmann shallow water model: a basic scheme, a second-order scheme, and a centred scheme. Although the force is applied in the streaming step of the lattice Boltzmann model, the acceleration is [...] Read more.

This work compares three forcing schemes for a recently introduced cascaded lattice Boltzmann shallow water model: a basic scheme, a second-order scheme, and a centred scheme. Although the force is applied in the streaming step of the lattice Boltzmann model, the acceleration is also considered in the transformation to central moments. The model performance is tested for one and two dimensional benchmarks. Full article

(This article belongs to the Special Issue Combined Numerical and Experimental Methodology for Fluid–Structure Interactions in Free Surface Flows)

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18 pages, 2557 KiB

Open AccessEditor’s ChoiceArticle

A Three-Stage Hybrid Model for Space-Time Analysis of Water Resources Carrying Capacity: A Case Study of Jilin Province, China

by Tong Liu, Xiaohua Yang, Leihua Geng and Boyang Sun

Water 2020, 12(2), 426; https://doi.org/10.3390/w12020426 - 5 Feb 2020

Cited by 14 | Viewed by 3348

Abstract

Water shortage, water pollution, shrinking water area and water mobility are the main contents of the water resources crisis, which are widespread in the social and economic development of Jilin Province. In this paper, a three-stage hybrid model integrating evaluation, prediction and regulation [...] Read more.

Water shortage, water pollution, shrinking water area and water mobility are the main contents of the water resources crisis, which are widespread in the social and economic development of Jilin Province. In this paper, a three-stage hybrid model integrating evaluation, prediction and regulation is constructed by combining the load-balance method and the system dynamics method. Using this model, the current states of water resources carrying capacity (WRCC) in 2017 and the trend of water demand/available from 2018 to 2030 were obtained. Using the orthogonal test method, the optimal combination program of agricultural and industrial water efficiency regulation and water resources allocation was selected. The results show that the pressure of the human–water resources system in Changchun, Liaoyuan and Baicheng is greater than the support, and the other six cities are not overloaded. The water demand in Jilin Province and its nine cities will increase from 2018 to 2030, if the current socio-economic development pattern is maintained. Therefore, we change the water quantity carrying capacity index by controlling agriculture, industrial water efficiency and trans-regional water transfer. Compared with 2015, among the optimal program obtained, the change range of the water use per 10,000 RMB of agricultural output is (−5%, 25%), and the water use per 10,000 RMB of industrial added value is (−45%, −35%), and the maximum water transfer is 1.5 billion m³ per year in 2030. This study analyzes the development pattern of WRCC in the process of water conservancy modernization in Jilin Province and provides reference for other provinces to make the similar plan. Full article

(This article belongs to the Special Issue Advances in Urban Groundwater and Sustainable Water Resources Management and Planning)

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16 pages, 8669 KiB

Open AccessEditor’s ChoiceArticle

Flooding of Piazza San Marco (Venice): Physical Model Tests to Evaluate the Overtopping Discharge

by Piero Ruol, Chiara Favaretto, Matteo Volpato and Luca Martinelli

Water 2020, 12(2), 427; https://doi.org/10.3390/w12020427 - 5 Feb 2020

Cited by 16 | Viewed by 5113

Abstract

This paper aims at evaluating the wave overtopping discharge over the pavement of “Piazza S. Marco” (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the [...] Read more.

This paper aims at evaluating the wave overtopping discharge over the pavement of “Piazza S. Marco” (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the “Basilica S. Marco”. In fact, the MO.S.E. (MOdulo Sperimentale Elettromeccanico) system is designed to keep the water level below a certain value, for the safety of the lagoon, but it does not guarantee the defence of the Piazza, where flooding is still possible, being its pavement locally much lower than the maximum expected water level. To completely defend the Piazza, specific additional works are planned to prevent the back-flow through the natural drainage system (now the primary pathway) or by filtration or by overtopping. This paper investigates on the overtopping mechanism, under conditions compatible with a fully operational MO.S.E. system, through 2-D experiments. The pavement of the Piazza is gently sloping towards the masonry quay which, in some parts is formed by 5 descending steps, and in some other parts, is just a vertical wall. Close to the “Marciana” Library, a critical part is present, with a slightly lower crest freeboard. In total, three cross-sections were examined in the 36 m long wave flume of the Padova University. The test programme includes 10 irregular wave attacks and three different water levels. The test results differ considerably from the results of the available formulas, since the investigated cross-sections by far exceed their range of applicability. The presence of the steps affects only the reflection coefficient rather than the overtopping discharges. In general, if the waves incident to the Piazza are higher than 40 cm, which is a possible scenario, some other adaptation works must be considered, such as the pavement rise, temporary barriers or the reduction of the waves impacting the quay through, for instance, floating breakwaters. Full article

(This article belongs to the Special Issue Interaction between Waves and Maritime Structures)

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