Water

21 pages, 5240 KiB

Open AccessEditor’s ChoiceArticle

The Impact of Multi-Projects on the Alteration of the Flow Regime in the Middle and Lower Course of the Hanjiang River, China

by Xin Yin, Jianyun Zhang and Jie Chen

Water 2020, 12(8), 2301; https://doi.org/10.3390/w12082301 - 17 Aug 2020

Cited by 15 | Viewed by 3134

Abstract

A large number of water resources development projects have significantly changed the natural flow regime of the middle and lower reaches of the Hanjiang River, especially the Danjiangkou Reservoir, cascade reservoirs, the South-to-North Water Diversion Middle Line Project and their compensation projects, completed [...] Read more.

A large number of water resources development projects have significantly changed the natural flow regime of the middle and lower reaches of the Hanjiang River, especially the Danjiangkou Reservoir, cascade reservoirs, the South-to-North Water Diversion Middle Line Project and their compensation projects, completed in 1973, 2000, and 2014, respectively. The daily streamflow data of three stations in the middle and lower mainstream of the Hanjiang River are divided into four periods corresponding to pre-impact (1954–1973), interim (1974–1999), transition (2000–2013) and post-impact (2014–2018). Eco-flow metrics and indicators of hydrologic alteration (IHA) were used to study the change of natural flow regime. The annual streamflow decreased gradually during the four periods. The construction of the Danjiangkou Reservoir increased streamflow, minimum flow value, and the number of reversals in the dry season along the middle and lower course of the Hanjiang River. Moreover, the dam reduced streamflow, maximum flow value, low pulse duration, and the rise and fall rates in the wet season. Additionally, the streamflow reduced corresponding to the completion of cascade reservoirs and the Middle Route of South-to-North Water Diversion Project. In particular, the streamflow decreased drastically from July to September, affected by the Middle Route of the South-to-North Water Diversion Project. Furthermore, the compensation projects, such as the Yangtze-Hanjiang Water Diversion Project, mitigate the reduction of streamflow from July to September in the downstream. The study provides insights into the ecological and economic benefits associated with water resources development and use in the mainstream of the middle and lower course of the Hanjiang River for the achievement of sustainable development in the region. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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19 pages, 11907 KiB

Open AccessEditor’s ChoiceArticle

The Potential Use of Geophysical Methods to Identify Cavities, Sinkholes and Pathways for Water Infiltration

by Yawar Hussain, Rogerio Uagoda, Welitom Borges, José Nunes, Omar Hamza, Cristobal Condori, Khurram Aslam, Jie Dou and Martín Cárdenas-Soto

Water 2020, 12(8), 2289; https://doi.org/10.3390/w12082289 - 14 Aug 2020

Cited by 42 | Viewed by 6805

Abstract

The use of geophysical characterization of karst systems can provide an economical and non-invasive alternative for extracting information about cavities, sinkholes, pathways for water infiltration as well as the degree of karstification of underlying carbonate rocks. In the present study, three geophysical techniques, [...] Read more.

The use of geophysical characterization of karst systems can provide an economical and non-invasive alternative for extracting information about cavities, sinkholes, pathways for water infiltration as well as the degree of karstification of underlying carbonate rocks. In the present study, three geophysical techniques, namely, Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT) and Very Low Frequency Electromagnetic (VLFEM) methods were applied at three different locations in relation to fluvial karst, which is listed as an environmentally sensitive area in Rio Vermelho, Mambaí, Goiás, Brazil. In the data acquisition phase, the GPR, direct-current (DC) resistivity and VLFEM profiles were obtained at the three locations in the area. Data were analyzed using commonly adopted processing workflows. The GPR results showed a well-defined lithology of the site based on the amplitude of the signal and radar typologies. On the other hand, the inverted resistivity cross-sections showed a three-layered stratigraphy, pathways of water infiltration and the weathered structures in carbonate (Bambui group). The interpretation of VLFEM as contours of current density resulted from Fraser and Karous–Hjelt filters, indicated the presence of conductive structures (high apparent current density) that might be linked to the weathered carbonate and other conductive and resistive anomalies associated with the water-filled and dry cavities (cave), respectively. The results encourage the integrated application of geophysical techniques such as the reconnaissance for further detailed characterization of the karst areas. Full article

(This article belongs to the Section Hydrology)

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17 pages, 3583 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exergy Optimization of a Solar Collector in Flat Plate Shape Equipped with Elliptical Pipes Filled with Turbulent Nanofluid Flow: A Study for Thermal Management

by Sara Rostami, Mohammad Sepehrirad, Amin Dezfulizadeh, Ahmed Kadhim Hussein, Aysan Shahsavar Goldanlou and Mostafa Safdari Shadloo

Water 2020, 12(8), 2294; https://doi.org/10.3390/w12082294 - 14 Aug 2020

Cited by 64 | Viewed by 5338

Abstract

In this paper, forced convection of a multiwalled carbon nanotube (MWCNT)–water nanofluid (NF) in a new flat plate solar collector (FPSC) equipped with elliptical pipes instead of circular ones is investigated. The three-dimensional conservation equations were solved in the domain with the finite [...] Read more.

In this paper, forced convection of a multiwalled carbon nanotube (MWCNT)–water nanofluid (NF) in a new flat plate solar collector (FPSC) equipped with elliptical pipes instead of circular ones is investigated. The three-dimensional conservation equations were solved in the domain with the finite volume method (FVM) based on the semi-implicit method for pressure linked equations (SIMPLE) algorithm. The laminar-turbulent range of the Reynolds number (Re) and the volume fraction of the NF (ϕ) were 50–12,000 and 0–0.1, respectively. The optimization process was accomplished through the comparison of diverse parameters to attain the optimal case with the highest exergy efficiency. In this study, it was concluded that, in the case of using elliptical pipes instead of circular tubes, the time that the fluid was inside the FPSC increased, which led to an increase in the outlet temperature, while the exergy efficiency of the FPSC increased. Additionally, it was observed that using elliptical pipes enhanced the outlet fluid temperature, energy efficiency, and exergy efficiency. Generally, while the trend of exergy efficiency variation with effective parameters was rising, applying elliptical pipes caused the efficiency to increase. In addition, the exergy efficiency variation decreased when these parameters were changed. The highest value of exergy efficiency was 7.1%. On the other hand, for each specific FPSC, there was a unique mass flow rate at which the exergy efficiency reached its maximum value, and for higher mass flow rates, the efficiency was slightly diminished and then remained unchanged. Finally, the highest exergy efficiency was achieved for ϕ = 0.10%. Full article

(This article belongs to the Special Issue Pipeline Fluid Mechanics 2020)

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23 pages, 6941 KiB

Open AccessEditor’s ChoiceArticle

Seasonal and Interannual Trends of Oceanographic Parameters over 40 Years in the Northern Adriatic Sea in Relation to Nutrient Loadings Using the EMODnet Chemistry Data Portal

by Federica Grilli, Stefano Accoroni, Francesco Acri, Fabrizio Bernardi Aubry, Caterina Bergami, Marina Cabrini, Alessandra Campanelli, Michele Giani, Stefano Guicciardi, Mauro Marini, Francesca Neri, Antonella Penna, Pierluigi Penna, Alessandra Pugnetti, Mariangela Ravaioli, Francesco Riminucci, Fabio Ricci, Cecilia Totti, Pierluigi Viaroli and Stefano Cozzi

Water 2020, 12(8), 2280; https://doi.org/10.3390/w12082280 - 13 Aug 2020

Cited by 75 | Viewed by 4698

Abstract

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation [...] Read more.

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation maps and statistical models were applied to investigate seasonal and spatial variability, as well as decadal trends of temperature, salinity, chlorophyll-a and nutrients. This analysis shows that sea surface temperature increased by +0.36% year⁻¹ over four decades. Annual mean flow of the Po River markedly changed due to the occurrence of periods of persistent drought, whereas the frequency of flow rates higher than 3000 m³ s⁻¹ decreased between 2006 and 2015. Moreover, we observed a long-term decrease in surface phosphate concentrations in Po River water (−1.34% year⁻¹) and in seawater (in summer −2.56% year⁻¹) coupled, however, to a significant increase in nitrate concentration in seawater (+3.80% year⁻¹) in almost all seasons. These changes indicate that the nutrient concentrations in the NAS have been largely modulated, in the last forty years, by the evolution of environmental management practices and of the runoff. This implies that further alteration of the marine environment must be expected as a consequence of the climate changes. Full article

(This article belongs to the Special Issue Anthropogenic and Climatic Disturbances in Freshwater and Coastal Ecosystems: Interactive Impacts and Expected Threats)

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15 pages, 2115 KiB

Open AccessEditor’s ChoiceArticle

Response of Soil Water Dynamics to Rainfall on A Collapsing Gully Slope: Based on Continuous Multi-Depth Measurements

by Zhi-Yun Jiang, Xue-Dan Wang, Si-Yi Zhang, Bin He, Xiao-Li Zhao, Fan-Ling Kong, Dan Feng and Yu-Chao Zeng

Water 2020, 12(8), 2272; https://doi.org/10.3390/w12082272 - 13 Aug 2020

Cited by 5 | Viewed by 2089

Abstract

Soil water conditions play an important role in the formation of a collapsing gully, but we are still at the early stages of understanding how the soil water changes on the slope after different rainfall events due to a lack of high-frequency continuous [...] Read more.

Soil water conditions play an important role in the formation of a collapsing gully, but we are still at the early stages of understanding how the soil water changes on the slope after different rainfall events due to a lack of high-frequency continuous field observations. This study aimed to reveal the response of soil water dynamics to rainfall events for different slope aspects and positions based on continuous multi-depth observations of soil water on a typical collapsing gully slope from 2017 to 2019 in Wuhua County, Guangdong Province, China. The vegetation characteristics and soil properties were investigated, and the storage of soil water was also calculated. The results showed that the dynamics and storage of soil water varied with the slope aspect, slope position and vegetation cover. The response time of the soil water to intensive rainfall events on the sunny slope was shorter than that on the shady slope, while soil water storage in the sunny slope was significantly lower than in the shady slope (p < 0.01). For the different slope positions, the soil water response time to the intensive rainfall events on the upper slope was shorter than that in the middle slope, while the soil water storage in the middle slope was significantly higher than on the upper slope. This was mainly due to the redistribution runoff from the upper slope to middle slope, delaying the process by which rainwater infiltrated into the soil layers. Moreover, vegetation significantly allayed the response of soil water dynamics to an intensive rainfall event but increased the storage of soil water, owing to the protection of soil surface from rain and conservation of high soil clay content. The bare area in the middle position of the sunny slope was speculated to be the potential source of the collapsing gully because it lacked the cover of vegetation. Our findings highlight the importance of soil water dynamics on the formation of a collapsing gully and provided valuable insights for the optimization of soil conservation and management practices for collapsing erosion. Full article

(This article belongs to the Section Water Erosion and Sediment Transport)

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48 pages, 25786 KiB

Open AccessEditor’s ChoiceArticle

Minimal Building Flood Fragility and Loss Function Portfolio for Resilience Analysis at the Community Level

by Omar M. Nofal and John W. van de Lindt

Water 2020, 12(8), 2277; https://doi.org/10.3390/w12082277 - 13 Aug 2020

Cited by 32 | Viewed by 8069

Abstract

Current flood vulnerability analyses rely on deterministic methods (e.g., stage–damage functions) to quantify resulting damage and losses to the built environment. While such approaches have been used extensively by communities, they do not enable the propagation of uncertainty into a risk- or resilience-informed [...] Read more.

Current flood vulnerability analyses rely on deterministic methods (e.g., stage–damage functions) to quantify resulting damage and losses to the built environment. While such approaches have been used extensively by communities, they do not enable the propagation of uncertainty into a risk- or resilience-informed decision process. In this paper, a method that allows the development of building fragility and building loss functions is articulated and applied to develop an archetype portfolio that can be used to model buildings in a typical community. The typical single-variable flood vulnerability function, normally based on flood depth, is extended to a multi-variate flood vulnerability function, which is a function of both flood depth and flood duration, thereby creating fragility surfaces. The portfolio presented herein consists of 15 building archetypes that can serve to populate a community-level model to predict damage and resulting functionality from a scenario flood event. The prediction of damage and functionality of buildings within a community is the first step in developing risk-informed mitigation decisions to improve community resilience. Full article

(This article belongs to the Section Hydrology)

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24 pages, 6057 KiB

Open AccessEditor’s ChoiceArticle

Determination of Actual Evapotranspiration and Crop Coefficients of California Date Palms Using the Residual of Energy Balance Approach

by Aliasghar Montazar, Robert Krueger, Dennis Corwin, Alireza Pourreza, Cayle Little, Sonia Rios and Richard L. Snyder

Water 2020, 12(8), 2253; https://doi.org/10.3390/w12082253 - 11 Aug 2020

Cited by 15 | Viewed by 7060

Abstract

As water scarcity becomes of greater concern in arid and semi-arid regions due to altered weather patterns, greater and more accurate knowledge regarding evapotranspiration of crops produced in these areas is of increased significance to better manage limited water resources. This study aimed [...] Read more.

As water scarcity becomes of greater concern in arid and semi-arid regions due to altered weather patterns, greater and more accurate knowledge regarding evapotranspiration of crops produced in these areas is of increased significance to better manage limited water resources. This study aimed at determining the actual evapotranspiration (ET_a) and crop coefficients (K_a) in California date palms. The residual of energy balance method using a combination of surface renewal and eddy covariance techniques was applied to measure ET_a in six commercial mature date palm orchards (8–22 years old) over one year. The experimental orchards represent various soil types and conditions, irrigation management practices, canopy characteristics, and the most common date cultivars in the region. The results demonstrated considerable variability in date palm consumptive water use, both spatially and temporally. The cumulative ET_a (CET_a) across the six sites ranged from 1299 to 1501 mm with a mean daily ET_a of 7.2 mm day⁻¹ in June–July and 1.0 mm day⁻¹ in December at the site with the highest crop water consumption. The mean monthly K_a values varied between 0.63 (December) and 0.90 (June) in the non-salt-affected, sandy loam soil date palms with an average density of 120 plants ha⁻¹ and an average canopy cover and tree height of more than 80% and 11.0 m, respectively. However, the values ranged from 0.62 to 0.75 in a silty clay loam saline-sodic date palm orchard with 55% canopy cover, density of 148 plants ha⁻¹, and 7.3 m tree height. Inverse relationships were derived between the CET_a and soil salinity (EC_e) in the crop root zone; and between the mean annual K_a and EC_e. This information addresses the immediate needs of date growers for irrigation management in the region and enables them to more efficiently utilize water and to achieve full economic gains in a sustainable manner, especially as water resources become less available or more expensive. Full article

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

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14 pages, 2366 KiB

Open AccessEditor’s ChoiceArticle

Effective Adsorption of Reactive Black 5 onto Hybrid Hexadecylamine Impregnated Chitosan-Powdered Activated Carbon Beads

by Mohammadtaghi Vakili, Haider M. Zwain, Amin Mojiri, Wei Wang, Fatemeh Gholami, Zahra Gholami, Abdulmoseen S. Giwa, Baozhen Wang, Giovanni Cagnetta and Babak Salamatinia

Water 2020, 12(8), 2242; https://doi.org/10.3390/w12082242 - 9 Aug 2020

Cited by 30 | Viewed by 4550

Abstract

In this study, hexadecylamine (HDA) impregnated chitosan-powder activated carbon (Ct-PAC) composite beads were successfully prepared and applied to adsorption of the anionic dye reactive black 5 (RB5) in aqueous solution. The Ct-PAC-HDA beads synthesized with 0.2 g powdered activated carbon (PAC) and 0.04 [...] Read more.

In this study, hexadecylamine (HDA) impregnated chitosan-powder activated carbon (Ct-PAC) composite beads were successfully prepared and applied to adsorption of the anionic dye reactive black 5 (RB5) in aqueous solution. The Ct-PAC-HDA beads synthesized with 0.2 g powdered activated carbon (PAC) and 0.04 g HDA showed the highest dye removal efficiency. The prepared beads were characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Various adsorption parameters, i.e., adsorbent dosage, pH, and contact time, which affect the adsorption performance, were studied in a series of batch experiments. The obtained adsorption data were found to be better represented by Freundlich (R² = 0.994) and pseudo-second-order (R² = 0.994) models. Moreover, it was ascertained that the adsorption of RB5 onto Ct-PAC-HDA beads is pH-dependent, and the maximum Langmuir adsorption capacity (666.97 mg/g) was observed at pH 4. It was also proved that Ct-PAC-HDA beads were regenerable for repeated use in the adsorption process. Full article

(This article belongs to the Special Issue Wastewater Treatment: Current and Future Techniques)

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19 pages, 11323 KiB

Open AccessEditor’s ChoiceArticle

Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia)

by Sofie Annys, Tesfaalem Ghebreyohannes and Jan Nyssen

Water 2020, 12(8), 2237; https://doi.org/10.3390/w12082237 - 8 Aug 2020

Cited by 15 | Viewed by 7389

Abstract

Due to renewed interest in hydropower dams in the face of climate change, it is important to assess dam operations and management in combination with downstream impacts on rivers in (semi-)arid environments. In this study, the impacts of the Tekeze hydropower dam on [...] Read more.

Due to renewed interest in hydropower dams in the face of climate change, it is important to assess dam operations and management in combination with downstream impacts on rivers in (semi-)arid environments. In this study, the impacts of the Tekeze hydropower dam on downstream hydrology and river morphology were investigated, including impacts under normal and extreme reservoir operation conditions. Field observations, in-depth interviews, repeat terrestrial photographs, multi-year high-resolution satellite images, daily reservoir water levels and data on hourly to daily energy production were collected and studied. The results show that high flows (Q₅) have declined (with factor 5), low flows (Q₉₅) have increased (with factor 27), seasonal flow patterns have smoothened, river beds have incised (up to 4 m) and locally aggraded near tributary confluences. The active river bed has narrowed by 31%, which was accelerated by the gradual emergence of Tamarix nilotica and fruit plantations. A new post-dam equilibrium had been reached until it was disrupted by the 2018 emergency release, caused by reservoir management and above-normal reservoir inflow, and causing extensive erosion and agricultural losses downstream. Increased floodplain occupation for irrigated agriculture consequently provides an additional argument for reservoir operation optimization to avoid future risks for riparian communities. Full article

(This article belongs to the Special Issue Fluvial Geomorphology and River Management)

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14 pages, 10540 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

An Improved Immersed Boundary Method for Simulating Flow Hydrodynamics in Streams with Complex Terrains

by Yalan Song, Yong G. Lai and Xiaofeng Liu

Water 2020, 12(8), 2226; https://doi.org/10.3390/w12082226 - 7 Aug 2020

Cited by 3 | Viewed by 4064

Abstract

Three-dimensional (3D) computational fluid dynamic (CFD) simulations have gained substantial popularity in recent years for stream flow modelling. The complex terrain in streams is usually represented by a 3D mesh conforming to the terrain geometry. Such terrain-conforming meshes are time-consuming to generate. In [...] Read more.

Three-dimensional (3D) computational fluid dynamic (CFD) simulations have gained substantial popularity in recent years for stream flow modelling. The complex terrain in streams is usually represented by a 3D mesh conforming to the terrain geometry. Such terrain-conforming meshes are time-consuming to generate. In this work, an immersed boundary method is developed in an existing terrain-conforming CFD model named U²RANS as an alternative, in which terrains are represented implicitly in the Cartesian background mesh. An improved two-layer wall function is proposed in the framework of the k-ε turbulence model, with the aim of producing accurate and smooth wall shear stress distribution and paving the way for future model development on sediment transport and scour modeling. The improvement overcomes the inherent discontinuity and nonlinearity of the two-layer velocity profile, which causes error in the estimation of shear velocity. The new algorithm utilizes a distance control on the image point in immersed boundary method and a modification of velocity prediction in the laminar layer. The improved immersed boundary method is tested with 1D, 2D, and 3D cases, and comparisons with flume experiments show promising results. Full article

(This article belongs to the Special Issue Multi-Dimensional Modeling of Flow and Sediment Transport)

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17 pages, 3271 KiB

Open AccessEditor’s ChoiceArticle

Integrating Climatic and Physical Information in a Bayesian Hierarchical Model of Extreme Daily Precipitation

by Charlotte A. Love, Brian E. Skahill, John F. England, Gregory Karlovits, Angela Duren and Amir AghaKouchak

Water 2020, 12(8), 2211; https://doi.org/10.3390/w12082211 - 6 Aug 2020

Cited by 2 | Viewed by 2692

Abstract

Extreme precipitation events are often localized, difficult to predict, and available records are often sparse. Improving frequency analysis and describing the associated uncertainty are essential for regional hazard preparedness and infrastructure design. Our primary goal is to evaluate incorporating Bayesian model averaging (BMA) [...] Read more.

Extreme precipitation events are often localized, difficult to predict, and available records are often sparse. Improving frequency analysis and describing the associated uncertainty are essential for regional hazard preparedness and infrastructure design. Our primary goal is to evaluate incorporating Bayesian model averaging (BMA) within a spatial Bayesian hierarchical model framework (BHM). We compare results from two distinct regions in Oregon with different dominating rainfall generation mechanisms, and a region of overlap. We consider several Bayesian hierarchical models from relatively simple (location covariates only) to rather complex (location, elevation, and monthly mean climatic variables). We assess model predictive performance and selection through the application of leave-one-out cross-validation; however, other model assessment methods were also considered. We additionally conduct a comprehensive assessment of the posterior inclusion probability of covariates provided by the BMA portion of the model and the contribution of the spatial random effects term, which together characterize the pointwise spatial variation of each model’s generalized extreme value (GEV) distribution parameters within a BHM framework. Results indicate that while using BMA may improve analysis of extremes, model selection remains an important component of tuning model performance. The most complex model containing geographic and information was among the top performing models in western Oregon (with relatively wetter climate), while it performed among the worst in the eastern Oregon (with relatively drier climate). Based on our results from the region of overlap, site-specific predictive performance improves when the site and the model have a similar annual maxima climatology—winter storm dominated versus summer convective storm dominated. The results also indicate that regions with greater temperature variability may benefit from the inclusion of temperature information as a covariate. Overall, our results show that the BHM framework with BMA improves spatial analysis of extremes, especially when relevant (physical and/or climatic) covariates are used. Full article

(This article belongs to the Special Issue Stochastic Modelling of Hydrometeorological Processes for Engineering Applications)

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35 pages, 5497 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Seven Good Reasons for Integrating Terrestrial and Marine Spatial Datasets in Changing Environments

by Mariacristina Prampolini, Alessandra Savini, Federica Foglini and Mauro Soldati

Water 2020, 12(8), 2221; https://doi.org/10.3390/w12082221 - 6 Aug 2020

Cited by 19 | Viewed by 6703

Abstract

A comprehensive understanding of environmental changes taking place in coastal regions relies on accurate integration of both terrestrial and submerged geo-environmental datasets. However, this practice is hardly implemented because of the high (or even prohibitive) survey costs required for submerged areas and the [...] Read more.

A comprehensive understanding of environmental changes taking place in coastal regions relies on accurate integration of both terrestrial and submerged geo-environmental datasets. However, this practice is hardly implemented because of the high (or even prohibitive) survey costs required for submerged areas and the frequent low accessibility of shallow areas. In addition, geoscientists are used to working on land or at sea independently, making the integration even more challenging. Undoubtedly new methods and techniques of offshore investigation adopted over the last 50 years and the latest advances in computer vision have played a crucial role in allowing a seamless combination of terrestrial and marine data. Although efforts towards an innovative integration of geo-environmental data from above to underwater are still in their infancy, we have identified seven topics for which this integration could be of tremendous benefit for environmental research: (1) geomorphological mapping; (2) Late-Quaternary changes of coastal landscapes; (3) geoarchaeology; (4) geoheritage and geodiversity; (5) geohazards; (6) marine and landscape ecology; and (7) coastal planning and management. Our review indicates that the realization of seamless DTMs appears to be the basic condition to operate a comprehensive integration of marine and terrestrial data sets, so far exhaustively achieved in very few case studies. Technology and interdisciplinarity will be therefore critical for the development of a holistic approach to understand our changing environments and design appropriate management measures accordingly. Full article

(This article belongs to the Special Issue Landscapes and Landforms of Terrestrial and Marine Areas)

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17 pages, 934 KiB

Open AccessEditor’s ChoiceReview

Separating the Impacts of Climate Change and Human Activities on Runoff: A Review of Method and Application

by Feng Zeng, Ming-Guo Ma, Dong-Rui Di and Wei-Yu Shi

Water 2020, 12(8), 2201; https://doi.org/10.3390/w12082201 - 5 Aug 2020

Cited by 44 | Viewed by 5295

Abstract

Separating the impact of climate change and human activities on runoff is an important topic in hydrology, and a large number of methods and theories have been widely used. In this paper, we review the current papers on separating the impacts of climate [...] Read more.

Separating the impact of climate change and human activities on runoff is an important topic in hydrology, and a large number of methods and theories have been widely used. In this paper, we review the current papers on separating the impacts of climate and human activities on runoff, summarize the progress of relevant research methods and applications in recent years, and discuss future research needs and directions. Full article

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29 pages, 7202 KiB

Open AccessEditor’s ChoiceArticle

Rapidly Accelerating Deforestation in Cambodia’s Mekong River Basin: A Comparative Analysis of Spatial Patterns and Drivers

by Sapana Lohani, Thomas E. Dilts, Peter J. Weisberg, Sarah E. Null and Zeb S. Hogan

Water 2020, 12(8), 2191; https://doi.org/10.3390/w12082191 - 4 Aug 2020

Cited by 35 | Viewed by 11067

Abstract

The Mekong River is a globally important river system, known for its unique flood pulse hydrology, ecological productivity, and biodiversity. Flooded forests provide critical terrestrial nutrient inputs and habitat to support aquatic species. However, the Mekong River is under threat from anthropogenic stressors, [...] Read more.

The Mekong River is a globally important river system, known for its unique flood pulse hydrology, ecological productivity, and biodiversity. Flooded forests provide critical terrestrial nutrient inputs and habitat to support aquatic species. However, the Mekong River is under threat from anthropogenic stressors, including deforestation from land cultivation and urbanization, and dam construction that inundates forests and encourages road development. This study investigated spatio-temporal patterns of deforestation in Cambodia and portions of neighboring Laos and Vietnam that form the Srepok–Sesan–Sekong watershed. A random forest model predicted tree cover change over a 25-year period (1993–2017) using the Landsat satellite archive. Then, a statistical predictive deforestation model was developed using annual-resolution predictors such as land-cover change, hydropower development, forest fragmentation, and socio-economic, topo-edaphic and climatic predictors. The results show that almost 19% of primary forest (nearly 24,000 km²) was lost, with more deforestation in floodplain (31%) than upland (18%) areas. Our results corroborate studies showing extremely high rates of deforestation in Cambodia. Given the rapidly accelerating deforestation rates, even in protected areas and community forests, influenced by a growing population and economy and extreme poverty, our study highlights landscape features indicating an increased risk of future deforestation, supporting a spatial framework for future conservation and mitigation efforts. Full article

(This article belongs to the Special Issue Channels for Change: Integrating Multiple Disciplines for New Frontiers in Managing the Mekong River Basin)

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18 pages, 13309 KiB

Open AccessEditor’s ChoiceArticle

Modeling Long-Term Temporal Variation of Dew Formation in Jordan and Its Link to Climate Change

by Nahid Atashi, Dariush Rahimi, Mustafa Al Kuisi, Anwar Jiries, Henri Vuollekoski, Markku Kulmala, Timo Vesala and Tareq Hussein

Water 2020, 12(8), 2186; https://doi.org/10.3390/w12082186 - 3 Aug 2020

Cited by 13 | Viewed by 3807

Abstract

In this study, we performed model simulations to investigate the spatial, seasonal, and annual dew yield during 40 years (1979–2018) at ten locations reflecting the variation of climate and environmental conditions in Jordan. In accordance with the climate zones in Jordan, the dew [...] Read more.

In this study, we performed model simulations to investigate the spatial, seasonal, and annual dew yield during 40 years (1979–2018) at ten locations reflecting the variation of climate and environmental conditions in Jordan. In accordance with the climate zones in Jordan, the dew formation had distinguished characteristics features with respect to the yield, seasonal variation, and spatial variation. The highest water dew yield (an overall annual mean cumulative dew yield as high as 88 mm) was obtained for the Mountains Heights Plateau, which has a Mediterranean climate. The least dew yield (as low as 19 mm) was obtained in Badia, which has an arid climate. The dew yield had a decreasing trend in the past 40 years due to climate change impacts such as increased desertification and the potential of sand and dust storms in the region. In addition, increased anthropogenic air pollution slows down the conversion of vapor to liquid phase change, which also impacts the potential of dew formation. The dew yield showed three distinguished seasonal patterns reflecting the three climates in Jordan. The Mountains Heights Plateau (Mediterranean climate) has the highest potential for dew harvesting (especially during the summer) than Badia (semi-arid climate). Full article

(This article belongs to the Special Issue Climate Change Effects on Hydrological Processes, Water Resources, Ecosystems and Agriculture)

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20 pages, 6431 KiB

Open AccessEditor’s ChoiceArticle

Source Apportionment Assessment of Marine Sediment Contamination in a Post-Industrial Area (Bagnoli, Naples)

by Sara Giglioli, Loris Colombo, Pasquale Contestabile, Luigi Musco, Giovanna Armiento, Renato Somma, Diego Vicinanza and Arianna Azzellino

Water 2020, 12(8), 2181; https://doi.org/10.3390/w12082181 - 3 Aug 2020

Cited by 18 | Viewed by 3862

Abstract

The area of Bagnoli (Gulf of Naples, central Tyrrhenian Sea) has been heavily exposed to pollution for over a century due to the presence of industrial sites along its coastline. The aim of this study is to analyze contaminant concentrations (i.e., heavy metals [...] Read more.

The area of Bagnoli (Gulf of Naples, central Tyrrhenian Sea) has been heavily exposed to pollution for over a century due to the presence of industrial sites along its coastline. The aim of this study is to analyze contaminant concentrations (i.e., heavy metals and hydrocarbons) in seabed sediments through a statistical multivariate approach. Multivariate methods permit us to describe the pollution dynamics affecting the area and distinguish between anthropogenic and natural pollution sources. Additionally, the association between contamination patterns and the wave climate characteristics of the gulf (i.e., wave period, direction, height, power, and energy) is investigated. The study confirms that the main contamination source in the Bagnoli bay is anthropogenic activities (i.e., former steel plant and sewage discharges) for the majority of investigated pollutants. It also provides evidence, however, for the potential co-existence of multiple anthropogenic and geogenic sources of arsenic and other metals that may be originating also from the water-rock interaction and submarine volcanic emissions in the Phlegraean area. Full article

(This article belongs to the Special Issue Coastal Vulnerability and Mitigation Strategies: From Monitoring to Applied Research )

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15 pages, 3811 KiB

Open AccessEditor’s ChoiceArticle

Analytical Method for Lithium Isotopes Determination by Thermal Ionization Mass Spectrometry: A Useful Tool for Hydrogeochemical Applications

by Ilenia Arienzo, Marcello Liotta, Lorenzo Brusca, Massimo D’Antonio, Federica Lupone and Ciro Cucciniello

Water 2020, 12(8), 2182; https://doi.org/10.3390/w12082182 - 3 Aug 2020

Cited by 4 | Viewed by 3494

Abstract

The low temperature realm such as the geothermal systems, characterized by a large variety of near-Earth surface processes, has been the object of several isotopic studies, some of them including lithium isotopes. However, much work can still be done to systematically use lithium [...] Read more.

The low temperature realm such as the geothermal systems, characterized by a large variety of near-Earth surface processes, has been the object of several isotopic studies, some of them including lithium isotopes. However, much work can still be done to systematically use lithium as tracer of geochemical processes in deep and shallow Earth reservoirs. A pilot study has been performed for the determination of lithium-isotope ratio by thermal ionization mass spectrometry (TIMS), a technique poorly employed with respect to other methods such as inductively coupled plasma mass spectrometry, being more time consuming. Lithium has been extracted by chromatographic techniques on columns through an ion exchange process from both natural and reference samples. The isotope composition (⁶Li/⁷Li) expressed in terms of δ⁷Li has been determined in dynamic and static mode for comparative purposes, by using two different types of thermal ionization mass spectrometers. The results presented in this work agree with the data reported in the literature, opening a new perspective to future research on continental geothermal systems and groundwater domains, spread over the entire Italian peninsula. This research is based on the use of chemical and isotopic data, whereas it does not include lithium isotopes. These latter may provide a huge contribution in studying both volcanic products and fluids from active volcanic areas, including the superposed geothermal systems, and may represent a new tool for research and surveillance. Full article

(This article belongs to the Special Issue Geochemistry of Groundwater)

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27 pages, 13622 KiB

Open AccessEditor’s ChoiceArticle

Relative Sea-Level Rise and Potential Submersion Risk for 2100 on 16 Coastal Plains of the Mediterranean Sea

by Fabrizio Antonioli, Giovanni De Falco, Valeria Lo Presti, Lorenzo Moretti, Giovanni Scardino, Marco Anzidei, Davide Bonaldo, Sandro Carniel, Gabriele Leoni, Stefano Furlani, Antonella Marsico, Marcello Petitta, Giovanni Randazzo, Giovanni Scicchitano and Giuseppe Mastronuzzi

Water 2020, 12(8), 2173; https://doi.org/10.3390/w12082173 - 1 Aug 2020

Cited by 51 | Viewed by 8676

Abstract

The coasts of the Mediterranean Sea are dynamic habitats in which human activities have been conducted for centuries and which feature micro-tidal environments with about 0.40 m of range. For this reason, human settlements are still concentrated along a narrow coastline strip, where [...] Read more.

The coasts of the Mediterranean Sea are dynamic habitats in which human activities have been conducted for centuries and which feature micro-tidal environments with about 0.40 m of range. For this reason, human settlements are still concentrated along a narrow coastline strip, where any change in the sea level and coastal dynamics may impact anthropic activities. In the frame of the RITMARE and the Copernicus Projects, we analyzed light detection and ranging (LiDAR) and Copernicus Earth Observation data to provide estimates of potential marine submersion for 2100 for 16 small-sized coastal plains located in the Italian peninsula and four Mediterranean countries (France, Spain, Tunisia, Cyprus) all characterized by different geological, tectonic and morphological features. The objective of this multidisciplinary study is to provide the first maps of sea-level rise scenarios for 2100 for the IPCC RCP 8.5 and Rahmstorf (2007) projections for the above affected coastal zones, which are the locations of touristic resorts, railways, airports and heritage sites. On the basis of our model (eustatic projection for 2100, glaciohydrostasy values and tectonic vertical movement), we provide 16 high-definition submersion maps. We estimated a potential loss of land for the above areas of between about 148 km² (IPCC-RCP8.5 scenario) and 192 km² (Rahmstorf scenario), along a coastline length of about 400 km. Full article

(This article belongs to the Special Issue Relative Sea-Level Changes and their Impact on Coastal Zones)

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23 pages, 3206 KiB

Open AccessEditor’s ChoiceArticle

Legal Analysis and Case Study on the Choice between Setting Environmental Flows by Using Reclaimed Water in Non-Permanent Rivers and the Sustainable Management of Groundwater in Southeast Spain

by Andrés Molina-Giménez

Water 2020, 12(8), 2171; https://doi.org/10.3390/w12082171 - 31 Jul 2020

Cited by 3 | Viewed by 2991

Abstract

This article studies the interaction between two environmental objectives actively pursued in water governance. On the one hand, the convenience of establishing or raising a minimum circulating flow in surface water bodies so to improve their quantitative and qualitative status. On the other [...] Read more.

This article studies the interaction between two environmental objectives actively pursued in water governance. On the one hand, the convenience of establishing or raising a minimum circulating flow in surface water bodies so to improve their quantitative and qualitative status. On the other hand, the need to carry out an intelligent management of aquifers avoiding their overexploitation. In the case study, the proposal consisting of increasing the minimum flow rate on a non-permanent river by means of discharging reclaimed water is studied. Such strategy jeopardizes the recovery of a number of overexploited aquifers since reclaimed water is currently being used for farming under the condition to proportionally reduce groundwater withdrawals. The aim is to discuss whether it is reasonable and rational to ensure continuous flows in water courses which do not have that pattern according to their natural dynamics to the detriment of other environmental or socioeconomic goals. In order to help decision makers to make a right choice, a set of criteria based on legal principles is proposed. According to the principles of minimum intervention, rationality and reasonableness, proportionality, and water economy, it is concluded that the use of reclaimed water to set higher environmental flows in discontinuous and ephemeral streams should only have a minor role in water policies, especially whether it may jeopardize other critical environmental goals. Full article

(This article belongs to the Special Issue Water Economics and Water Distribution Management)

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14 pages, 2906 KiB

Open AccessEditor’s ChoiceArticle

Nuisance Algae in Ballast Water Facing International Conventions. Insights from DNA Metabarcoding in Ships Arriving in Bay of Biscay

by Alba Ardura, Yaisel J. Borrell, Sara Fernández, Mónica González Arenales, José L. Martínez and Eva Garcia-Vazquez

Water 2020, 12(8), 2168; https://doi.org/10.3390/w12082168 - 31 Jul 2020

Cited by 18 | Viewed by 3299

Abstract

Ballast water is one of the main vectors of transport of nuisance species among marine ports. Neither treatment nor interchange completely reduces the risk of ballast water containing DNA from harmful species, being a signal of potential threat. However, although there are some [...] Read more.

Ballast water is one of the main vectors of transport of nuisance species among marine ports. Neither treatment nor interchange completely reduces the risk of ballast water containing DNA from harmful species, being a signal of potential threat. However, although there are some efficient treatments, they are not available on all ships and there might be some technological/economical constrains for their active and routine usage. Understanding what routes lead to a higher risk of contamination is important for designing targeted surveillance. We analysed ballast water from seven ships arriving in Gijon port (south Bay of Biscay, Spain). DNA metabarcoding was employed for identification of exotic species and harmful algae. One ship carried DNA of 20 risk species in the ballast water. Three ships contained DNA of only one risk species, and three ships had none. Seventy two algae species were found, 22.2% are exotic to the Bay of Biscay and 11.1% are catalogued as harmful. The results demonstrated the importance of continuous surveillance of ballast water. Full article

(This article belongs to the Special Issue Applications of Environmental DNA and RNA in Aquatic Ecosystems)

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18 pages, 3774 KiB

Open AccessEditor’s ChoiceReview

Habitats and Diversity of Subterranean Macroscopic Freshwater Invertebrates: Main Gaps and Future Trends

by Elzbieta Dumnicka, Tanja Pipan and David C. Culver

Water 2020, 12(8), 2170; https://doi.org/10.3390/w12082170 - 31 Jul 2020

Cited by 4 | Viewed by 2653

Abstract

Caves are the best studied aquatic subterranean habitat, but there is a wide variety of these habitats, ranging in depth below the surface and size of the spaces (pore or habitat size). Both factors are important in setting limits to species composition and [...] Read more.

Caves are the best studied aquatic subterranean habitat, but there is a wide variety of these habitats, ranging in depth below the surface and size of the spaces (pore or habitat size). Both factors are important in setting limits to species composition and richness. In addition to caves, among the most important shallow aquatic subterranean habitats are the hyporheal (underflow of rivers and streams), the hypotelminorheal (very superficial drainages with water exiting in seeps), epikarst, and calcrete aquifers. Although it is little studied, both body size and species composition in the different habitats is different. Because of high levels of endemism and difficulty in access, no subterranean habitats are well sampled, even caves. However, there are enough data for robust generalizations about some geographic patterns. Individual hotspot caves are concentrated in the Dinaric region of southern Europe, and overall, tropical regions have fewer obligate aquatic cave dwellers (stygobionts). In all subterranean aquatic habitats, regional diversity is much higher than local diversity, but local diversity (especially single cave diversity) may be a useful predictor of regional species richness. In Europe there is a ridge of high aquatic subterranean species richness basically extending east from the French–Spanish border. Its cause may be either high productivity or that long-term temperature oscillations are at a minimum. With increased collecting and analysis, global and continental trends should become clearer. Full article

(This article belongs to the Special Issue Freshwater Macroinvertebrates: Main Gaps and Future Trends)

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18 pages, 4760 KiB

Open AccessEditor’s ChoiceArticle

Biodegradation of Amoxicillin, Tetracyclines and Sulfonamides in Wastewater Sludge

by Chu-Wen Yang, Chien Liu and Bea-Ven Chang

Water 2020, 12(8), 2147; https://doi.org/10.3390/w12082147 - 30 Jul 2020

Cited by 75 | Viewed by 6550

Abstract

The removal of antibiotics from the aquatic environment has received great interest. The aim of this study is to examine degradation of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), amoxicillin (AMO), sulfamethazine (SMZ), sulfamethoxazole (SMX), sulfadimethoxine (SDM) in sludge. Four antibiotic-degrading bacterial strains, SF1 [...] Read more.

The removal of antibiotics from the aquatic environment has received great interest. The aim of this study is to examine degradation of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), amoxicillin (AMO), sulfamethazine (SMZ), sulfamethoxazole (SMX), sulfadimethoxine (SDM) in sludge. Four antibiotic-degrading bacterial strains, SF1 (Pseudmonas sp.), A12 (Pseudmonas sp.), strains B (Bacillus sp.), and SANA (Clostridium sp.), were isolated, identified and tested under aerobic and anaerobic conditions in this study. Batch experiments indicated that the addition of SF1 and A12 under aerobic conditions and the addition of B and SANA under anaerobic conditions increased the biodegradation of antibiotics in sludge. Moreover, the results of repeated addition experiments indicated that the efficiency of the biodegradation of antibiotics using the isolated bacterial strains could be maintained for three degradation cycles. Two groups of potential microbial communities associated with the aerobic and anaerobic degradation of SMX, AMO and CTC in sludge were revealed. Twenty-four reported antibiotics-degrading bacterial genera (Achromobacter, Acidovorax, Acinetobacter, Alcaligenes, Bacillus, Burkholderia, Castellaniella, Comamonas, Corynebacterium, Cupriavidus, Dechloromonas, Geobacter, Gordonia, Klebsiella, Mycobacterium, Novosphingobium, Pandoraea, Pseudomonas, Rhodococcus, Sphingomonas, Thauera, Treponema, Vibrio and Xanthobacter) were found in both the aerobic and anaerobic groups, suggesting that these 24 bacterial genera may be the major antibiotic-degrading bacteria in sludge. Full article

(This article belongs to the Special Issue Ecological and Health Risk of Soils, Sediments, and Water Contamination)

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21 pages, 3747 KiB

Open AccessEditor’s ChoiceArticle

Adsorptive Behavior of an Activated Carbon for Bisphenol A Removal in Single and Binary (Bisphenol A—Heavy Metal) Solutions

by M.A. Martín-Lara, M. Calero, A. Ronda, I. Iáñez-Rodríguez and C. Escudero

Water 2020, 12(8), 2150; https://doi.org/10.3390/w12082150 - 30 Jul 2020

Cited by 53 | Viewed by 5265

Abstract

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial [...] Read more.

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial wastewater solutions, testing the reduction of bisphenol A in synthetic solutions by a commercial activated carbon, AC-40, in batch mode. Besides, mixtures of bisphenol A and different heavy metal cations were also studied. So far, no works have reported a complete study about bisphenol A removal by this activated carbon including the use of this material to remove BPA in the presence of metal cations. First, adsorption experiments were performed in batch changing pH, dose of adsorbent, initial bisphenol A concentration and contact time. Results showed greater retention of bisphenol A by increasing the acidity of the medium. Further, the percentage of bisphenol A adsorbed increased with increasing contact time. The selected conditions for the rest of the experiments were pH 5 and a contact time of 48 h. In addition, an increase in retention of bisphenol A when the dose of adsorbent increased was observed. Then, specific experiments were carried out to define the kinetics and the adsorption isotherm. Equilibrium data were adequately fitted to a Langmuir isotherm and the kinetics data fitted well to the pseudo-second-order model. The maximum adsorption capacity provided by Langmuir model was 94.34 mg/g. Finally, the effect of the presence of other heavy metals in water solution on the adsorption of bisphenol A was analyzed. Binary tests revealed competition between the adsorbates and a significant selectivity toward bisphenol A. Finally, the study of the adsorption performance in three consecutive adsorption–desorption cycles showed efficiencies higher than 90% in all cycles, indicating that the activated carbon has good reusability. Full article

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

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14 pages, 1970 KiB

Open AccessEditor’s ChoiceReview

Resilience of Primary Food Production to a Changing Climate: On-Farm Responses to Water-Related Risks

by Tim Hess, Jerry Knox, Ian Holman and Chloe Sutcliffe

Water 2020, 12(8), 2155; https://doi.org/10.3390/w12082155 - 30 Jul 2020

Cited by 14 | Viewed by 4701

Abstract

Water is a fundamental component in primary food production, whether it be rainfall, irrigation used to water crops, or for supplying drinking water for animals, while the amount of water in the soil determines it capacity to support machinery and animals. We identify [...] Read more.

Water is a fundamental component in primary food production, whether it be rainfall, irrigation used to water crops, or for supplying drinking water for animals, while the amount of water in the soil determines it capacity to support machinery and animals. We identify that UK agriculture is exposed to five main water-related risks: agricultural drought, scarcity of water resources, restrictions on the right to abstract water, excess soil water, and inundation. Projected milder, wetter winters and hotter, drier summers by the end of the century will change the frequency, persistence, or severity of each of these risks. This paper critically reviews and synthesizes the scientific literature on the impact of these risks on primary food production and the technological and managerial strategies employed to build resilience to these changing risks. At the farm scale, the emphasis has been on strategies to build robustness to reduce the impact of a water-related risk. However, collaborative partnerships allow for a more optimal allocation of water during times of scarcity. Enhancing cross-scale interactions, learning opportunities, and catchment-scale autonomy will be key to ensuring the agricultural system can build adaptive and transformational capacity. Full article

(This article belongs to the Special Issue Perspectives on River Catchment Resilience)

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22 pages, 6751 KiB

Open AccessEditor’s ChoiceArticle

Building for Nature: Preserving Threatened Bird Habitat in Port Design

by Jos R. M. Muller, Ying-Chi Chan, Theunis Piersma, Yong-ping Chen, Stefan G. J. Aarninkhof, Chris J. Hassell, Jian-feng Tao, Zheng Gong, Zheng Bing Wang and Dirk S. van Maren

Water 2020, 12(8), 2134; https://doi.org/10.3390/w12082134 - 28 Jul 2020

Cited by 6 | Viewed by 4667

Abstract

The fast economic development of the People’s Republic of China has created an increasing demand for usable land, resulting in large-scale land reclamations along the coastal zone. One of these regions is Tongzhou Bay (Jiangsu coast), a region characterized by large intertidal mudflats [...] Read more.

The fast economic development of the People’s Republic of China has created an increasing demand for usable land, resulting in large-scale land reclamations along the coastal zone. One of these regions is Tongzhou Bay (Jiangsu coast), a region characterized by large intertidal mudflats and deep tidal channels with potential for the development of agri-aquaculture and the construction of a deep-sea port. However, these intertidal mudflats also provide vital ecosystem services and support many wildlife species, including several endangered migratory shorebirds within the East Asian–Australasian Flyway. With increasing realization of the importance of maintaining such ecological values, a more integrated coastal development strategy is needed. This study aims to develop a sustainable integrated design for the Tongzhou Bay port, following a “Building with Nature” approach. We use a morphodynamic model to compute habitat suitability for two shorebird species (Great Knot Calidris tenuirostris and Bar-tailed Godwit Limosa lapponica). Several port configurations were developed on the basis of three design criteria: (1) create area for future port development, whilst (2) preserving existing high-value ecotopes for shorebirds and (3) enhance the natural accretion rate of such ecotopes. Simulation results showed a clear difference in siltation patterns, preservation and enhancement of preferred ecotopes. This work therefore demonstrates the potential and importance of morphological and habitat suitability modelling when designing large-scale reclamations and port constructions, especially in dynamic areas such as Tongzhou Bay. Full article

(This article belongs to the Special Issue Nature-Based Solutions for Coastal Engineering and Management)

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25 pages, 4896 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

River Water Quality of the Selenga-Baikal Basin: Part I—Spatio-Temporal Patterns of Dissolved and Suspended Metals

by Nikolay Kasimov, Galina Shinkareva, Mikhail Lychagin, Natalia Kosheleva, Sergey Chalov, Margarita Pashkina, Josefin Thorslund and Jerker Jarsjö

Water 2020, 12(8), 2137; https://doi.org/10.3390/w12082137 - 28 Jul 2020

Cited by 18 | Viewed by 5003

Abstract

Lake Baikal is the largest freshwater body on Earth, once famous for its pristine conditions. However, the lake and its drainage basin with their unique ecosystems have in recent decades been subject to both climate warming above the world average and severe anthropogenic [...] Read more.

Lake Baikal is the largest freshwater body on Earth, once famous for its pristine conditions. However, the lake and its drainage basin with their unique ecosystems have in recent decades been subject to both climate warming above the world average and severe anthropogenic pressures from mining and agriculture. Although previous studies have targeted various hydroclimatic, geochemical, and biological conditions of the Lake Baikal basin, the heterogeneous nature and large size of the basin leave considerable knowledge gaps regarding ongoing metal contamination of the basin’s suspended sediments and waters. To address these knowledge gaps, the main objectives of this study are to (i) determine regional background values for water and suspended sediment quality with respect to multiple metals (representing undisturbed conditions) and (ii) further evaluate spatio-temporal concentration patterns of these metals, including regions with heavy anthropogenic impacts. We synthesize data from extensive field measurements within the Selenga River basin performed between 2011 and 2016, covering over 100 sampling locations. Results show that although the background metal concentrations (of both dissolved and suspended metal forms) in the alkaline Selenga River waters were close to the world averages, metal concentrations of up to two orders of magnitude above the background values were seen for Zn, As, Cd, Cu, Mo, and Pb in regions subject to anthropogenic impacts (cities and the mining industry). Specifically, dissolved As levels within the Selenga River basin were 2–5 times higher than the world average and well above the global guideline value in several regions. Notable hotspots for anthropogenic impacts of Cd were particularly found in Zakamensk and Ulaanbaatar. Our results highlight clear anthropogenic impacts and large-scale spreading of several pollutants of concern, with risks even to downstream parts including the Selenga delta and Lake Baikal. We expect that these results will aid in increasing the understanding of large-scale metal transport processes, as well as for designing relevant measures to mitigate further spreading of metals to Lake Baikal. Full article

(This article belongs to the Special Issue Pollutant/Nutrient Transport and Fate under Changing Hydroclimatic Conditions)

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19 pages, 5484 KiB

Open AccessEditor’s ChoiceArticle

Effects of Water Stress on Photosynthesis, Yield, and Water Use Efficiency in Winter Wheat

by Wenhui Zhao, Leizhen Liu, Qiu Shen, Jianhua Yang, Xinyi Han, Feng Tian and Jianjun Wu

Water 2020, 12(8), 2127; https://doi.org/10.3390/w12082127 - 27 Jul 2020

Cited by 136 | Viewed by 14237

Abstract

Drought has become one of the major constraints to agricultural development, particularly in areas that lack water. Studying the effects of different water stresses on the photosynthesis, growth, yield, water use efficiency (WUE) and irrigation water productivity (IWP) of winter wheat will provide [...] Read more.

Drought has become one of the major constraints to agricultural development, particularly in areas that lack water. Studying the effects of different water stresses on the photosynthesis, growth, yield, water use efficiency (WUE) and irrigation water productivity (IWP) of winter wheat will provide data for the development of scientific irrigation strategies for water-saving agricultural methods. According to the size of the field water capacity, four different water stress levels were set, i.e., 30–40% (severe stress), 40–50% (moderate stress), 50–60% (mild stress) and 60–80% (well-watered) of field water capacity, controlling the amount of irrigation through an automatic irrigation system. The results showed that the seasonal changes in photosynthetic parameters, such as net photosynthetic rate (Pn), intercellular carbon concentration (Ci), stomatal conductance (Gs) and transpiration (E), significantly decreased under moderate and severe stress. As a result, the height, biomass and grain size of winter wheat decreased significantly, which led to low WUE and IWP. The Pn of the mild stress group only slightly decreased compared to that of the well-watered group, and was actually higher during the flowering and grain-filling stages, resulting in increases in dry biomass and 1000 grain weight of 2.07% and 1.95%, respectively. Higher WUE and IWP were attributed to higher yields and less water use. Thus, mild stress (60–80% field water capacity) resulted in the optimal use of water resources without a significant reduction in yield in the North China Plain (NCP). Therefore, mild stress can be considered a suitable environment for winter wheat growth in arid areas. Full article

(This article belongs to the Special Issue Irrigation Scheduling and Crop Water Relations)

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15 pages, 1274 KiB

Open AccessEditor’s ChoiceArticle

The Role of Experience and Different Sources of Knowledge in Shaping Flood Risk Awareness

by Elena Mondino, Anna Scolobig, Marco Borga and Giuliano Di Baldassarre

Water 2020, 12(8), 2130; https://doi.org/10.3390/w12082130 - 27 Jul 2020

Cited by 36 | Viewed by 6013

Abstract

Understanding what makes people vulnerable to flooding is key in informing the risk management process. Non-structural measures, such as risk communication, can reduce vulnerability by improving flood risk awareness, but they require a deep understanding of which factors influence risk awareness, and how. [...] Read more.

Understanding what makes people vulnerable to flooding is key in informing the risk management process. Non-structural measures, such as risk communication, can reduce vulnerability by improving flood risk awareness, but they require a deep understanding of which factors influence risk awareness, and how. We analysed and untangled the role of experience with, and knowledge of, floods by conducting a survey in a municipality in North-eastern Italy that was hit by a flash flood in 2018. The results show that previous experience with floods influences risk awareness not only directly, but also indirectly through the knowledge that was gained from that experience. In addition, specific (as opposed to generic) definitions of experience have been found to be better suited for exploring their effects on risk awareness. Based on the literature and on our results, we propose an experience-knowledge typology to help unravel the complex role that these two variables play in shaping flood risk awareness. Full article

(This article belongs to the Special Issue Flood Risk in the Anthropocene)

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37 pages, 2713 KiB

Open AccessEditor’s ChoiceArticle

Breaching Barriers: The Fight for Indigenous Participation in Water Governance

by Ryan E. Emanuel and David E. Wilkins

Water 2020, 12(8), 2113; https://doi.org/10.3390/w12082113 - 25 Jul 2020

Cited by 17 | Viewed by 17047

Abstract

Indigenous peoples worldwide face barriers to participation in water governance, which includes planning and permitting of infrastructure that may affect water in their territories. In the United States, the extent to which Indigenous voices are heard—let alone incorporated into decision-making—depends heavily on whether [...] Read more.

Indigenous peoples worldwide face barriers to participation in water governance, which includes planning and permitting of infrastructure that may affect water in their territories. In the United States, the extent to which Indigenous voices are heard—let alone incorporated into decision-making—depends heavily on whether or not Native nations are recognized by the federal government. In the southeastern United States, non-federally recognized Indigenous peoples continue to occupy their homelands along rivers, floodplains, and wetlands. These peoples, and the Tribal governments that represent them, rarely enter environmental decision-making spaces as sovereign nations and experts in their own right. Nevertheless, plans to construct the Atlantic Coast Pipeline prompted non-federally recognized Tribes to demand treatment as Tribal nations during permitting. Actions by the Tribes, which are recognized by the state of North Carolina, expose barriers to participation in environmental governance faced by Indigenous peoples throughout the United States, and particularly daunting challenges faced by state-recognized Tribes. After reviewing the legal and political landscapes that Native nations in the United States must navigate, we present a case study focused on Atlantic Coast Pipeline planning and permitting. We deliberately center Native voices and perspectives, often overlooked in non-Indigenous narratives, to emphasize Indigenous actions and illuminate participatory barriers. Although the Atlantic Coast Pipeline was cancelled in 2020, the case study reveals four enduring barriers to Tribal participation: adherence to minimum standards, power asymmetries, procedural narrowing, and “color-blind” planning. We conclude by highlighting opportunities for federal and state governments, developers, and Indigenous peoples to breach these barriers. Full article

(This article belongs to the Special Issue Transboundary Water Governance: New Sights and Developments)

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13 pages, 3458 KiB

Open AccessEditor’s ChoiceArticle

Features and Control of Submerged Horizontal Vortex in Stepped Dissipation Wells

by Boran Zhang, Mengshan Shi, Lvtan Yao and Wuyi Wan

Water 2020, 12(8), 2117; https://doi.org/10.3390/w12082117 - 25 Jul 2020

Viewed by 2748

Abstract

Unlike a horizontal intake vortex, a submerged horizontal vortex is not bounded by a free surface. It has an axial air core submerged in a vessel such as a dissipation well. Due to the motion of its bound point (where the vortex ends), [...] Read more.

Unlike a horizontal intake vortex, a submerged horizontal vortex is not bounded by a free surface. It has an axial air core submerged in a vessel such as a dissipation well. Due to the motion of its bound point (where the vortex ends), the front wall of the dissipation well could be damaged by cavitation. The goals of this study are to (1) summarize general features underlying the formation and collapsing of horizontal vortices in dissipation wells; (2) identify the features of submerged horizontal vortices; and (3) propose potential measures to mitigate cavitation damage. Through scaling down experiments performed in a transparent dissipation well with two optical sensors, various boundary conditions have been carried out to accomplish this investigation. It was found that a wider inlet flow falling with mixed air can facilitate the generation of submerged horizontal vortices. The optimal mappings between the inlet discharge and the water head differential for maintaining the vortices have been summarized. Depending on different applications, two configurations are proposed to mitigate the adverse effects of submerged horizontal vortices. 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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22 pages, 5275 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dune Systems’ Characterization and Evolution in the Andalusia Mediterranean Coast (Spain)

by Rosa Molina, Giorgio Manno, Carlo Lo Re and Giorgio Anfuso

Water 2020, 12(8), 2094; https://doi.org/10.3390/w12082094 - 23 Jul 2020

Cited by 12 | Viewed by 3173

Abstract

This paper deals with the characterization and evolution of dune systems along the Mediterranean coast of Andalusia, in the South of Spain, a first step to assess their relevant value in coastal flood protection and in the determination of sound management strategies to [...] Read more.

This paper deals with the characterization and evolution of dune systems along the Mediterranean coast of Andalusia, in the South of Spain, a first step to assess their relevant value in coastal flood protection and in the determination of sound management strategies to protect such valuable ecological systems. Different dune types were mapped as well as dune toe position and fragmentation, which favors dune sensitivity to storms’ impacts, and human occupation and evolution from 1977 to 2001 and from 2001 to 2016. Within a GIS (Geographic Information System) project, 53 dune systems were mapped that summed a total length of ca. 106 km in 1977, differentiating three dune environments: (i) Embryo and mobile dunes (Type I), (ii) grass-fixed dunes (Type II) and (iii) stabilized dunes (Type III). A general decrease in dunes’ surfaces was recorded in the 1977–2001 period (−7.5 × 10⁶ m²), especially in Málaga and Almería provinces, and linked to dunes’ fragmentation and the increase of anthropic occupation (+2.3 × 10⁶ m²). During the 2001–2016 period, smaller changes in the level of fragmentation and in dunes’ surfaces were observed. An increase of dunes’ surfaces was only observed on stable or accreting beaches, both in natural and anthropic areas (usually updrift of ports). Full article

(This article belongs to the Special Issue Coastal Dynamic and Evolution)

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27 pages, 3127 KiB

Open AccessEditor’s ChoiceArticle

Emulation of a Process-Based Salinity Generator for the Sacramento–San Joaquin Delta of California via Deep Learning

by Minxue He, Liheng Zhong, Prabhjot Sandhu and Yu Zhou

Water 2020, 12(8), 2088; https://doi.org/10.3390/w12082088 - 23 Jul 2020

Cited by 9 | Viewed by 2984

Abstract

Salinity management is a subject of particular interest in estuarine environments because of the underlying biological significance of salinity and its variations in time and space. The foremost step in such management practices is understanding the spatial and temporal variations of salinity and [...] Read more.

Salinity management is a subject of particular interest in estuarine environments because of the underlying biological significance of salinity and its variations in time and space. The foremost step in such management practices is understanding the spatial and temporal variations of salinity and the principal drivers of these variations. This has traditionally been achieved with the assistance of empirical or process-based models, but these can be computationally expensive for complex environmental systems. Model emulation based on data-driven methods offers a viable alternative to traditional modeling in terms of computational efficiency and improving accuracy by recognizing patterns and processes that are overlooked or underrepresented (or overrepresented) by traditional models. This paper presents a case study of emulating a process-based boundary salinity generator via deep learning for the Sacramento–San Joaquin Delta (Delta), an estuarine environment with significant economic, ecological, and social value on the Pacific coast of northern California, United States. Specifically, the study proposes a range of neural network models: (a) multilayer perceptron, (b) long short-term memory network, and (c) convolutional neural network-based models in estimating the downstream boundary salinity of the Delta on a daily time-step. These neural network models are trained and validated using half of the dataset from water year 1991 to 2002. They are then evaluated for performance in the remaining record period from water year 2003 to 2014 against the process-based boundary salinity generation model across different ranges of salinity in different types of water years. The results indicate that deep learning neural networks provide competitive or superior results compared with the process-based model, particularly when the output of the latter are incorporated as an input to the former. The improvements are generally more noticeable during extreme (i.e., wet, dry, and critical) years rather than in near-normal (i.e., above-normal and below-normal) years and during low and medium ranges of salinity rather than high range salinity. Overall, this study indicates that deep learning approaches have the potential to supplement the current practices in estimating salinity at the downstream boundary and other locations across the Delta, and thus guide real-time operations and long-term planning activities in the Delta. Full article

(This article belongs to the Special Issue Numerical and Data-Driven Modelling in Coastal, Hydrological and Hydraulic Engineering)

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23 pages, 4505 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Distributed Storage of Stormwater in Sponge-Like Porous Bodies: Modelling Water Uptake

by T. Staffan Lundström, Hans O. Åkerstedt, I. A. Sofia Larsson, Jiri Marsalek and Maria Viklander

Water 2020, 12(8), 2080; https://doi.org/10.3390/w12082080 - 22 Jul 2020

Cited by 3 | Viewed by 2597

Abstract

An innovative concept of dynamic stormwater storage in sponge-like porous bodies (SPBs) is presented and modelled using first principles, for down-flow and up-flow variants of SPBs. The rate of inflow driven by absorption and/or capillary action into various porous material structures was computed [...] Read more.

An innovative concept of dynamic stormwater storage in sponge-like porous bodies (SPBs) is presented and modelled using first principles, for down-flow and up-flow variants of SPBs. The rate of inflow driven by absorption and/or capillary action into various porous material structures was computed as a function of time and found to be critically dependent on the type of structure and the porous material used. In a case study, the rates of inflow and storage filling were modelled for various conditions and found to match, or exceed, the rates of rainwater inflow and volume accumulation associated with two types of Swedish rainfalls, of 60-min duration and a return period of 10 years. Hence, the mathematical models indicated that the SPB devices studied could capture relevant amounts of water. The theoretical study also showed that the SPB concepts could be further optimized. Such findings confirmed the potential of dynamic SPB storage to control stormwater runoff and serve as one of numerous elements contributing to restoration of pre-urban hydrology in urban catchments. Finally, the issues to be considered in bringing this theoretical concept to a higher Technological Readiness Level were discussed briefly, including operational challenges. However, it should be noted that a proper analysis of such issues requires a separate study building on the current presentation of theoretical concepts. Full article

(This article belongs to the Special Issue Industrial and Environmental Fluid Mechanics)

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21 pages, 4166 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Probabilistic Prediction of Significant Wave Height Using Dynamic Bayesian Network and Information Flow

by Ming Li and Kefeng Liu

Water 2020, 12(8), 2075; https://doi.org/10.3390/w12082075 - 22 Jul 2020

Cited by 30 | Viewed by 3184

Abstract

Short-term prediction of wave height is paramount in oceanic operation-related activities. Statistical models have advantages in short-term wave prediction as complex physical process is substantially simplified. However, previous statistical models have no consideration in selection of predictive variables and dealing with prediction uncertainty. [...] Read more.

Short-term prediction of wave height is paramount in oceanic operation-related activities. Statistical models have advantages in short-term wave prediction as complex physical process is substantially simplified. However, previous statistical models have no consideration in selection of predictive variables and dealing with prediction uncertainty. This paper develops a machine learning model by combining the dynamic Bayesian network (DBN) with the information flow (IF) designated as DBN-IF. IF is focused on selecting the best predictive variables for DBN by causal analysis instead of correlation analysis. DBN for probabilistic prediction is constructed by structure learning and parameter learning with data mining. Based on causal theory, graph theory, and probability theory, the proposed DBN-IF model could deal with the uncertainty and shows great performance in significant wave height prediction compared with the artificial neural network (ANN), random forest (RF) and support vector machine (SVM) for all lead times. The interpretable DBN-IF is proven as a promising tool for nonlinear and uncertain wave height prediction. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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16 pages, 1892 KiB

Open AccessEditor’s ChoiceArticle

Bioremediation of Aquaculture Wastewater with Algal-Bacterial Biofilm Combined with the Production of Selenium Rich Biofertilizer

by Wei Han, Yufeng Mao, Yunpeng Wei, Peng Shang and Xu Zhou

Water 2020, 12(7), 2071; https://doi.org/10.3390/w12072071 - 21 Jul 2020

Cited by 27 | Viewed by 5471

Abstract

The discharge of aquaculture wastewater and the excessive selenium in aquaculture effluent caused by selenium addition to aquatic feed are posing a serious risk for the marine environment. In this study, batch tests were carried out to investigate the feasibility of utilizing algal–bacterial [...] Read more.

The discharge of aquaculture wastewater and the excessive selenium in aquaculture effluent caused by selenium addition to aquatic feed are posing a serious risk for the marine environment. In this study, batch tests were carried out to investigate the feasibility of utilizing algal–bacterial biofilm for the treatment of selenium-rich aquaculture wastewater. The effects of four different types of commercial biofilm carriers on the attached growth of biofilms and the contaminant removal capacity were examined. The braided cotton biofilm carrier had the best performance on biofilm growth, while in an exponential growth period the dry weight density of the biofilm was above 2.0 g L⁻¹. By utilizing the braided cotton carrier with a hydraulic retention time (HRT) of 6 days, the removal rate of N and P from the raw aquaculture wastewater was 88.5 ± 6.2% and 99.8 ± 0.2%, respectively. After that, the effects of different initial wastewater load ratios (IWLR) and HRT on the effluent quality of the treatment process were studied. The decrease in IWLR and the extension of HRT could improve the treatment performance. The effluent N, P and Se concentrations in the group with 50% IWLR and 6-day HRT were 0.75 ± 0.10 mg L⁻¹, 0.015 ± 0.02 mg L⁻¹, 35.2 ± 3.2 μg L⁻¹, respectively, indicating an effective removal of the main contaminants. The algal–bacterial biofilm harvested from the batch test was rich in N, P and Se, where the Se content was 21.8 ± 3.4 mg kg⁻¹, which has the potential to be used as an Se-rich biofertilizer. Full article

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

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14 pages, 1464 KiB

Open AccessEditor’s ChoiceConcept Paper

Macroplastic Storage and Remobilization in Rivers

by Maciej Liro, Tim van Emmerik, Bartłomiej Wyżga, Justyna Liro and Paweł Mikuś

Water 2020, 12(7), 2055; https://doi.org/10.3390/w12072055 - 20 Jul 2020

Cited by 97 | Viewed by 9912

Abstract

The paper presents a conceptual model of the route of macroplastic debris (>5 mm) through a fluvial system, which can support future works on the overlooked processes of macroplastic storage and remobilization in rivers. We divided the macroplastic route into (1) input, (2) [...] Read more.

The paper presents a conceptual model of the route of macroplastic debris (>5 mm) through a fluvial system, which can support future works on the overlooked processes of macroplastic storage and remobilization in rivers. We divided the macroplastic route into (1) input, (2) transport, (3) storage, (4) remobilization and (5) output phases. Phase 1 is mainly controlled by humans, phases 2–4 by fluvial processes, and phase 5 by both types of controls. We hypothesize that the natural characteristics of fluvial systems and their modification by dam reservoirs and flood embankments construction are key controls on macroplastic storage and remobilization in rivers. The zone of macroplastic storage can be defined as a river floodplain inundated since the beginning of widespread disposal of plastic waste to the environment in the 1960s and the remobilization zone as a part of the storage zone influenced by floodwaters and bank erosion. The amount of macroplastic in both zones can be estimated using data on the abundance of surface- and subsurface-stored macroplastic and the lateral and vertical extent of the zones. Our model creates the framework for estimation of how much plastic has accumulated in rivers and will be present in future riverscapes. Full article

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16 pages, 2391 KiB

Open AccessEditor’s ChoiceArticle

Shift Detection in Hydrological Regimes and Pluriannual Low-Frequency Streamflow Forecasting Using the Hidden Markov Model

by Larissa Zaira Rafael Rolim and Francisco de Assis de Souza Filho

Water 2020, 12(7), 2058; https://doi.org/10.3390/w12072058 - 20 Jul 2020

Cited by 10 | Viewed by 2671

Abstract

Improved water resource management relies on accurate analyses of the past dynamics of hydrological variables. The presence of low-frequency structures in hydrologic time series is an important feature. It can modify the probability of extreme events occurring in different time scales, which makes [...] Read more.

Improved water resource management relies on accurate analyses of the past dynamics of hydrological variables. The presence of low-frequency structures in hydrologic time series is an important feature. It can modify the probability of extreme events occurring in different time scales, which makes the risk associated with extreme events dynamic, changing from one decade to another. This article proposes a methodology capable of dynamically detecting and predicting low-frequency streamflow (16–32 years), which presented significance in the wavelet power spectrum. The Standardized Runoff Index (SRI), the Pruned Exact Linear Time (PELT) algorithm, the breaks for additive seasonal and trend (BFAST) method, and the hidden Markov model (HMM) were used to identify the shifts in low frequency. The HMM was also used to forecast the low frequency. As part of the results, the regime shifts detected by the BFAST approach are not entirely consistent with results from the other methods. A common shift occurs in the mid-1980s and can be attributed to the construction of the reservoir. Climate variability modulates the streamflow low-frequency variability, and anthropogenic activities and climate change can modify this modulation. The identification of shifts reveals the impact of low frequency in the streamflow time series, showing that the low-frequency variability conditions the flows of a given year. Full article

(This article belongs to the Special Issue Hydrology of Rivers and Lakes under Climate Change)

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42 pages, 7352 KiB

Open AccessEditor’s ChoiceReview

State of the Art and Recent Advancements in the Modelling of Land Subsidence Induced by Groundwater Withdrawal

by Artur Guzy and Agnieszka A. Malinowska

Water 2020, 12(7), 2051; https://doi.org/10.3390/w12072051 - 19 Jul 2020

Cited by 72 | Viewed by 11734

Abstract

Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension [...] Read more.

Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension of this phenomenon is usually extensive and is often difficult to define clearly. Aquifer compaction contributes to many socio-economic effects and high infrastructure-related damage costs. Currently, many methods are used to analyze aquifer compaction. These include the fundamental relationship between groundwater head and groundwater flow direction, water pressure and aquifer matrix compressibility. Such solutions enable satisfactory modelling results. However, further research is needed to allow more efficient modelling of aquifer compaction. Recently, satellite radar interferometry (InSAR) has contributed to significant progress in monitoring and determining the spatio-temporal land subsidence distributions worldwide. Therefore, implementation of this approach can pave the way to the development of more efficient aquifer compaction models. This paper presents (1) a comprehensive review of models used to predict land surface displacements caused by aquifer drainage, as well as (2) recent advances, and (3) a summary of InSAR implementation in recent years to support the aquifer compaction modelling process. Full article

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

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14 pages, 1866 KiB

Open AccessEditor’s ChoiceArticle

Kinetic and Prediction Modeling Studies of Organic Pollutants Removal from Municipal Wastewater using Moringa oleifera Biomass as a Coagulant

by Bashir Adelodun, Matthew Segun Ogunshina, Fidelis Odedishemi Ajibade, Taofeeq Sholagberu Abdulkadir, Hashim Olalekan Bakare and Kyung Sook Choi

Water 2020, 12(7), 2052; https://doi.org/10.3390/w12072052 - 19 Jul 2020

Cited by 26 | Viewed by 4757

Abstract

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of [...] Read more.

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of 50, 100, 150, 200 mg/L, and a control (0 mg/L) treatment were performed for a settling period of 250 min at room temperature. Kinetics and prediction variables of cumulative turbidity, BOD, and COD removal were estimated using simplified first order and modified Gompertz models. Results showed that the maximum removal of turbidity, BOD, and COD were 94.44%, 68.72%, and 57.61%, respectively, using an MO dose of 150 mg/L. Various kinetic parameters, such as rate constant (r), measured (RE_m) versus predicted (RE_p) cumulative removal, and specific pollutant removal rate (µ_m), were also maximum when an MO dose of 150 mg/L was added, the standard error being below 5%. The developed models were successfully validated over multiple observations. This study suggests low cost and sustainable removal of turbidity, BOD, and COD of municipal wastewater using MO seed biomass as a coagulant. Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment)

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24 pages, 5501 KiB

Open AccessEditor’s ChoiceReview

Flood Risk Analysis and Assessment, Applications and Uncertainties: A Bibliometric Review

by Andrés Díez-Herrero and Julio Garrote

Water 2020, 12(7), 2050; https://doi.org/10.3390/w12072050 - 18 Jul 2020

Cited by 56 | Viewed by 9233

Abstract

Studies looking at flood risk analysis and assessment (FRA) reviews are not customary, and they usually approach to methodological and spatial scale issues, uncertainty, mapping or economic damage topics. However, most of these reviews provide a snapshot of the scientific state of the [...] Read more.

Studies looking at flood risk analysis and assessment (FRA) reviews are not customary, and they usually approach to methodological and spatial scale issues, uncertainty, mapping or economic damage topics. However, most of these reviews provide a snapshot of the scientific state of the art of FRA that shows only a partial view, focused on a limited number of selected methods and approaches. In this paper, we apply a bibliometric analysis using the Web of Science (WoS) database to assess the historic evolution and future prospects (emerging fields of application) of FRA. The scientific production of FRA has increased considerably in the past decade. At the beginning, US researchers dominated the field, but now they have been overtaken by the Chinese. The Netherlands and Germany may be highlighted for their more complete analyses and assessments (e.g., including an uncertainty analysis of FRA results), and this can be related to the presence of competitive research groups focused on FRA. Regarding FRA fields of application, resilience analysis shows some growth in recent years while land planning, risk perception and risk warning show a slight decrease in the number of papers published. Global warming appears to dominate part of future FRA production, which affects both fluvial and coastal floods. This, together with the improvement of economic evaluation and psycho-social analysis, appear to be the main trends for the future evolution of FRA. Finally, we cannot ignore the increase in analysis using big data analysis, machine learning techniques, and remote sensing data (particularly in the case of UAV sensors data). Full article

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

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19 pages, 2056 KiB

Open AccessEditor’s ChoiceArticle

A Comparison and Validation of Saturated Hydraulic Conductivity Models

by Kaylyn S. Gootman, Elliott Kellner and Jason A. Hubbart

Water 2020, 12(7), 2040; https://doi.org/10.3390/w12072040 - 18 Jul 2020

Cited by 23 | Viewed by 4386

Abstract

Saturated hydraulic conductivity (K_sat) is fundamental to shallow groundwater processes. There is an ongoing need for observed and model validated K_sat values. A study was initiated in a representative catchment of the Chesapeake Bay Watershed in the Northeast USA, [...] Read more.

Saturated hydraulic conductivity (K_sat) is fundamental to shallow groundwater processes. There is an ongoing need for observed and model validated K_sat values. A study was initiated in a representative catchment of the Chesapeake Bay Watershed in the Northeast USA, to collect observed K_sat and validate five K_sat pedotransfer functions. Soil physical characteristics were quantified for dry bulk density (bdry), porosity, and soil texture, while K_sat was quantified using piezometric slug tests. Average bdry and porosity ranged from 1.03 to 1.30 g/cm³ and 0.51 to 0.61, respectively. Surface soil (0–5 cm) bdry and porosity were significantly (p < 0.05) lower and higher, respectively, than deeper soils (i.e., 25–30 cm; 45–50 cm). bdry and porosity were significantly different with location (p < 0.05). Average soil composition was 92% sand. Average K_sat ranged from 0.29 to 4.76 m/day and significantly differed (p < 0.05) by location. Four models showed that spatial variability in farm-scale K_sat estimates was small (CV < 0.5) and one model performed better when K_sat was 1.5 to 2.5 m/day. The two-parameter model that relied on silt/clay fractions performed best (ME = 0.78 m/day; SSE = 20.68 m²/day²; RMSE = 1.36 m/day). Results validate the use of simple, soil-property-based models to predict K_sat, thereby increasing model applicability and transferability. Full article

(This article belongs to the Special Issue Integrated Water Resources Research: Advancements in Understanding to Improve Future Sustainability)

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13 pages, 2333 KiB

Open AccessEditor’s ChoiceArticle

The Use of Permeable Interlocking Concrete Pavement to Filter Stormwater for Non-Potable Uses in Buildings

by Enedir Ghisi, Thiago Belotto and Liseane Padilha Thives

Water 2020, 12(7), 2045; https://doi.org/10.3390/w12072045 - 18 Jul 2020

Cited by 16 | Viewed by 7140

Abstract

A reduction in potable water demand in buildings could be made by using non-potable water for certain uses, such as flushing toilets. This represents a sustainable strategy that results in potable water savings while also using an underutilised resource. This work assesses the [...] Read more.

A reduction in potable water demand in buildings could be made by using non-potable water for certain uses, such as flushing toilets. This represents a sustainable strategy that results in potable water savings while also using an underutilised resource. This work assesses the use of permeable interlocking concrete pavement to filter stormwater that could be used for non-potable purposes in buildings. Two pavement model systems were tested. One of the model systems presents a filter course layer with coarse sand and the other model system has no filter course layer. In order to evaluate the filtering capacity, the model systems were exposed to rain events. The amount of water infiltrated through the layers was measured to represent the potential quantity available for use. Stormwater runoff samples were collected from a parking lot paved with impermeable interlocked blocks and then, these were tested in both model systems. Water samples were subjected to quality tests according to the parameters recommended by the Brazilian National Water Agency. The model system with no filter course showed filtering capacity higher (88.1%) than the one with a filter course layer (78.8%). The model system with a filter course layer was able to reduce fecal coliforms (54.7%), total suspended solids (62.5%), biochemical oxygen demand (78.8%), and total phosphorus concentrations (55.6%). Biochemical oxygen demand (42.4%) and total phosphorus concentrations (44.4%) increased in the model system with no filter course layer. In conclusion, one can state that the filter course layer used in permeable interlocking concrete pavement can contribute to decreasing pollutants and can improve stormwater quality. The use of permeable interlocking concrete pavement showed to be a potential alternative for filtering stormwater prior to subsequent treatment for non-potable uses in buildings. Full article

(This article belongs to the Special Issue Permeable Pavement Systems: Advances and Challenges in Stormwater Management)

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22 pages, 2723 KiB

Open AccessEditor’s ChoiceArticle

Students’ Scientific Evaluations of Water Resources

by Josh Medrano, Joshua Jaffe, Doug Lombardi, Margaret A. Holzer and Christopher Roemmele

Water 2020, 12(7), 2048; https://doi.org/10.3390/w12072048 - 18 Jul 2020

Cited by 11 | Viewed by 4691

Abstract

Socially-relevant and controversial topics, such as water issues, are subject to differences in the explanations that scientists and the public (herein, students) find plausible. Students need to be more evaluative of the validity of explanations (e.g., explanatory models) based on evidence when addressing [...] Read more.

Socially-relevant and controversial topics, such as water issues, are subject to differences in the explanations that scientists and the public (herein, students) find plausible. Students need to be more evaluative of the validity of explanations (e.g., explanatory models) based on evidence when addressing such topics. We compared two activities where students weighed connections between lines of evidence and explanations. In one activity, students were given four evidence statements and two models (one scientific and one non-scientific alternative); in the other, students chose four out of eight evidence statements and three models (two scientific and one non-scientific). Repeated measures analysis of variance (ANOVA) showed that both activities engaged students’ evaluations and differentially shifted students’ plausibility judgments and knowledge. A structural equation model suggested that students’ evaluation may influence post-instructional plausibility and knowledge; when students chose their lines of evidence and explanatory models, their evaluations were deeper, with stronger shifts toward a scientific stance and greater levels of post-instructional knowledge. The activities may help to develop students’ critical evaluation skills, a scientific practice that is key to understanding both scientific content and science as a process. Although effect sizes were modest, the results provided critical information for the final development and testing stage of these water resource instructional activities. Full article

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

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32 pages, 1447 KiB

Open AccessEditor’s ChoiceReview

The Application of Modified Natural Polymers in Toxicant Dye Compounds Wastewater: A Review

by Siti Aisyah Ishak, Mohamad Fared Murshed, Hazizan Md Akil, Norli Ismail, Siti Zalifah Md Rasib and Adel Ali Saeed Al-Gheethi

Water 2020, 12(7), 2032; https://doi.org/10.3390/w12072032 - 17 Jul 2020

Cited by 58 | Viewed by 7225

Abstract

The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human [...] Read more.

The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human health, potentially causing skin diseases and respiratory problems. The removal of dyes from wastewaters through chemical and physical processes has been addressed by many researchers. Currently, the use of natural and modified polymers for the removal of dyes from wastewater is becoming more common. Although modified polymers are preferred for the removal of dyes, due to their biodegradability and non-toxic nature, large amounts of polymers are required, resulting in higher costs. Surface-modified polymers are more effective for the removal of dyes from the wastewater. A survey of 80 recently published papers demonstrates that modified polymers have outstanding dye removal capabilities, and thus have a high applicability in industrial wastewater treatment. Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment)

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20 pages, 9283 KiB

Open AccessEditor’s ChoiceArticle

Drought Vulnerability in the United States: An Integrated Assessment

by Johanna Engström, Keighobad Jafarzadegan and Hamid Moradkhani

Water 2020, 12(7), 2033; https://doi.org/10.3390/w12072033 - 17 Jul 2020

Cited by 39 | Viewed by 10777

Abstract

Droughts are among the costliest natural hazards in the U.S. and globally. The severity of the hazard is closely related to a region’s ability to cope and recover from the event, an ability that depends on the region’s sensitivity and adaptive capacity. Here, [...] Read more.

Droughts are among the costliest natural hazards in the U.S. and globally. The severity of the hazard is closely related to a region’s ability to cope and recover from the event, an ability that depends on the region’s sensitivity and adaptive capacity. Here, the vulnerability to drought of each state within the contiguous U.S. is assessed as a function of exposure, sensitivity, and adaptive capacity, using socio-economic, climatic, and environmental indicators. The division of vulnerability into three sub-indices allows for an assessment of the driver(s) of vulnerability of a state and as such provides a foundation for drought mitigation and planning efforts. In addition, a probabilistic approach is used to investigate the sensitivity of vulnerability to the weighting scheme of indicators. The resulting geographic distribution of relative vulnerability of the states is partially a reflection of their heterogeneous climates but also highlights the importance of sustainable adaptation of the local economy to water availability in order to reduce sensitivity and to limit the impact of drought. As such, the study at hand offers insights to local and regional planners on how to effectively distribute funds and plan accordingly in order to reduce state-level drought vulnerability today and in the future. Full article

(This article belongs to the Special Issue Global Changes in Drought Frequency and Severity)

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21 pages, 4488 KiB

Open AccessEditor’s ChoiceArticle

Experimental Study at the Reservoir Head of Run-of-River Hydropower Plants in Gravel Bed Rivers. Part I: Delta Formation at Operation Level

by Christine Sindelar, Thomas Gold, Kevin Reiterer, Christoph Hauer and Helmut Habersack

Water 2020, 12(7), 2035; https://doi.org/10.3390/w12072035 - 17 Jul 2020

Cited by 9 | Viewed by 3623

Abstract

This study concerns scaled physical model tests of the delta formation process at the head of a run-of-river hydropower plant (RoR). It forms part of a larger research project to provide a scientific base for RoR sediment management strategies in medium-sized gravel bed [...] Read more.

This study concerns scaled physical model tests of the delta formation process at the head of a run-of-river hydropower plant (RoR). It forms part of a larger research project to provide a scientific base for RoR sediment management strategies in medium-sized gravel bed rivers. The physical model consisted of an idealized river having a width of 20 m, a mean slope of 0.005, a mean flow rate of 22 m³/s and a 1-year flood flow of 104 m³/s. The model scale was 1:20. For the experiments, five different grain sizes were used, covering a range of 14 to 120 mm at 1:1 scale. Experiments were carried out under mobile-bed conditions at flow rates which correspond to 50%–80% of a 1-year flood HQ₁. Even at the head of the reservoir, which is least influenced by the backwater effect of the RoR, sediment transport practically ceases for sediment fractions >14 mm for a flow rate of 0.7 × HQ₁. The whole sediment load coming from the undisturbed upstream section accumulates at the head of the reservoir. This delta formation is accompanied by a substantial rise in water levels. A spatio-temporal scheme of the delta formation was derived from the experiments. The study proved that the delta formation increases the flood risk at the head of the reservoir. Conversely, reservoir drawdowns at flood events of high probability may be a promising strategy to enhance sediment connectivity under the specified boundary conditions. Full article

(This article belongs to the Special Issue Sediment Management: Hydropower Improvement and Habitat Evaluation)

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18 pages, 2883 KiB

Open AccessEditor’s ChoiceArticle

The Effects of Hydraulic Jumps Instability on a Natural River Confluence: The Case Study of the Chiaravagna River (Italy)

by Annalisa De Leo, Alessia Ruffini, Matteo Postacchini, Marco Colombini and Alessandro Stocchino

Water 2020, 12(7), 2027; https://doi.org/10.3390/w12072027 - 16 Jul 2020

Cited by 9 | Viewed by 2580

Abstract

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, [...] Read more.

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, a scaled physical model of the Chiaravagna River and Ruscarolo Creek confluence has been used, retaining the realistic geometry of the reaches. This reach has been subject to frequent floods in the last twenty years and the entire area of the confluence has been redesigned to decrease the flood risk. A series of experiments has been performed varying the discharge on the two reaches and the geometrical configurations. Free surface levels and two dimensional horizontal velocities have been measured in several positions along the physical model. The analysis of the water levels and velocities reveals that oscillations characterised by large amplitude and low frequency occur under particular hydraulic conditions. These oscillations have been found to be triggered by the hydraulic jump toe instability of the smallest reach of the confluence. Aiming at reducing the amplitude of the oscillations, which can be of the order of the flow depth, possible constructive solutions have been tested to control or damp the oscillations. Indeed, the insertion of a longitudinal dyke at the confluence has proven to be an effective solution to limit the amplitude of the transversal oscillations. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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20 pages, 9662 KiB

Open AccessEditor’s ChoiceArticle

Hydropower Potential in the Alps under Climate Change Scenarios. The Chavonne Plant, Val D’Aosta

by Tommaso Duratorre, Giovanni Martino Bombelli, Giovanni Menduni and Daniele Bocchiola

Water 2020, 12(7), 2011; https://doi.org/10.3390/w12072011 - 15 Jul 2020

Cited by 14 | Viewed by 5390

Abstract

Present and prospective climate change will likely affect the hydrological cycle in sensitive areas, such as the Alps, thus impacting water-based activities. A most representative example is hydropower production, i.e., exploitation of water to produce energy. In the Italian Alps hydropower is strictly [...] Read more.

Present and prospective climate change will likely affect the hydrological cycle in sensitive areas, such as the Alps, thus impacting water-based activities. A most representative example is hydropower production, i.e., exploitation of water to produce energy. In the Italian Alps hydropower is strictly dependent upon water from snow and ice melt, and both are decreasing in response to global warming. Here, we study the effects of potential climate change scenarios at 2100 upon hydropower production from the Chavonne plant, in Valle d’Aosta region of Italy, a run-of-the-river (ROR) plant taking water from two high altitude glacierized catchments of Val di Cogne, and Valsavarenche. We use Poli-Hydro, a state-of-the-art hydrological model to mimic the hydrological budget of the area, including ice and snow melt share. Projections of the hydrological budget were built until 2100 by means of selected climate change scenarios, under proper downscaling. We used runs of three General Circulation Models (GCMs), EC-Earth, CCSM4, and ECHAM6.0 under three Representative Concentration Pathways RCP 2.6, RCP 4.5, and RCP 8.5 from AR5 of IPCC, and of their updated version under four Shared Socio-Economic Pathways SSP1 2.6, SSP2 4.5, SSP3 7.0, and SSP5 8.5 from AR6. We then assessed hydropower production changes against a recent control run CR period (2005–2015). Mean annual flow is estimated at 14.33 m³ s⁻¹ during CR, with ice melt contribution ca. 2%, and snow melt contribution ca. 44%. Ice cover in 2005 was estimated as 19.2 km², reaching in 2015, 9.93 km². Mean hydropower production was estimated at 153.72 GWh during the CR. Temperature would largely increase throughout the century (+0.93 °C on average at the half century, +2.45 °C at the end of the century). The ice covered area would be largely depleted (ca. −86%, −94% respectively), with reduced contribution of ice melt (0.23%, <0.1%, respectively) and snow melt (ca. 37%, 33%, respectively). Precipitation would show uncertain patterns, and hence incoming discharge at the plant would erratically vary (−29% to +24% half century, −27% to +59% end of century). Hydropower production displays a large dependence upon monthly discharge patterns, with mostly positive variations (+2.90% on average at half century, +6.95% on average at end of century), with its change driven by exceedance of plant’s capacity. Full article

(This article belongs to the Special Issue Impact of River Hydrology on Hydraulic Engineering and Hydropower)

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22 pages, 4234 KiB

Open AccessEditor’s ChoiceArticle

Hydrochemical and Isotopic Assessment of Groundwater in the Goda Mountains Range System. Republic of Djibouti (Horn of Africa)

by Ibrahim M. Ahmed, Mohamed Jalludin and Moumtaz Razack

Water 2020, 12(7), 2004; https://doi.org/10.3390/w12072004 - 15 Jul 2020

Cited by 11 | Viewed by 3153

Abstract

The hydrogeological system of the Goda Mountains Range (GMR) in the Republic of Djibouti (Horn of Africa), hosted by volcanic and sedimentary formations, is the only water resource in the Tadjourah region for more than 85,000 inhabitants. Water needs are expected to drastically [...] Read more.

The hydrogeological system of the Goda Mountains Range (GMR) in the Republic of Djibouti (Horn of Africa), hosted by volcanic and sedimentary formations, is the only water resource in the Tadjourah region for more than 85,000 inhabitants. Water needs are expected to drastically increase in the coming years, due to fast socio-economic development of the region. Accordingly, this system is under high pressure and should sustainably be exploited. However, little is known about the hydrogeology of this system. This study aims to improve the understanding of the hydrochemistry and the recharge processes of this system. The study is based on the combined interpretation of major ions, stable isotopes (¹⁸O, ²H), and radiogenic isotopes (³H, ¹⁴C). The interpretation of major ions contents using classical hydrochemical methods and principal component analysis highlighted that alteration of volcanic rocks minerals, coastal rainfall infiltration, and evaporation are the main processes from which groundwater acquires mineralization. Stable isotopes revealed that groundwater is of meteoric origin and has undergone high evaporation during infiltration. Radiogenic isotopes showed that groundwater in the basalts is mostly submodern to old, in relation with low hydraulic conductivity of the rocks and/or longer pathways through fissures from outcrop to subsurface. Groundwater in the rhyolites is much younger compared to the basalts due to faster infiltration. The sedimentary part, in connection with the rhyolites, has younger waters compared to the basalts, but older compared to the rhyolites. The overall results show that GMR is a fairly complex hydrogeological system, containing a resource made up of a mixture of waters of different ages. This study has made significant progress in understanding this system and is an initial step towards the sustainable exploitation of resources. Full article

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

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18 pages, 7730 KiB

Open AccessEditor’s ChoiceArticle

Energy Dissipation and Hydraulics of Flow over Trapezoidal–Triangular Labyrinth Weirs

by Amir Ghaderi, Rasoul Daneshfaraz, Mehdi Dasineh and Silvia Di Francesco

Water 2020, 12(7), 1992; https://doi.org/10.3390/w12071992 - 14 Jul 2020

Cited by 57 | Viewed by 5096

Abstract

In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal–triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to [...] Read more.

In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal–triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to the reservoir discharge channel. To simulate the free flow surface, the volume of fluid (VOF) method, and the Renormalization Group (RNG) k-ε model turbulence were adopted in the FLOW-3D software. The flow over the labyrinth weir (in both orientations) is simulated as a steady-state flow, and the discharge coefficient is validated with experimental data. The results highlighted that the numerical model shows proper coordination with experimental results and also the discharge coefficient decreases by decreasing the sidewall angle due to the collision of the falling jets for the high value of H/P (H: the hydraulic head, P: the weir height). Hydraulics of flow over TTLW has free flow conditions in low discharge and submerged flow conditions in high discharge. TTLW approximately dissipates the maximum amount of energy due to the collision of nappes in the upstream apexes and to the circulating flow in the pool generated behind the nappes; moreover, an increase in sidewall angle and weir height leads to reduced energy. The energy dissipation of TTLW is largest compared to vertical drop and has the least possible value of residual energy as flow increases. 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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