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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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22 pages, 2607 KiB  
Review
Diffuse Water Pollution from Agriculture: A Review of Nature-Based Solutions for Nitrogen Removal and Recovery
by Giuseppe Mancuso, Grazia Federica Bencresciuto, Stevo Lavrnić and Attilio Toscano
Water 2021, 13(14), 1893; https://doi.org/10.3390/w13141893 - 8 Jul 2021
Cited by 54 | Viewed by 15302
Abstract
The implementation of nature-based solutions (NBSs) can be a suitable and sustainable approach to coping with environmental issues related to diffuse water pollution from agriculture. NBSs exploit natural mitigation processes that can promote the removal of different contaminants from agricultural wastewater, and they [...] Read more.
The implementation of nature-based solutions (NBSs) can be a suitable and sustainable approach to coping with environmental issues related to diffuse water pollution from agriculture. NBSs exploit natural mitigation processes that can promote the removal of different contaminants from agricultural wastewater, and they can also enable the recovery of otherwise lost resources (i.e., nutrients). Among these, nitrogen impacts different ecosystems, resulting in serious environmental and human health issues. Recent research activities have investigated the capability of NBS to remove nitrogen from polluted water. However, the regulating mechanisms for nitrogen removal can be complex, since a wide range of decontamination pathways, such as plant uptake, microbial degradation, substrate adsorption and filtration, precipitation, sedimentation, and volatilization, can be involved. Investigating these processes is beneficial for the enhancement of the performance of NBSs. The present study provides a comprehensive review of factors that can influence nitrogen removal in different types of NBSs, and the possible strategies for nitrogen recovery that have been reported in the literature. Full article
(This article belongs to the Special Issue Advances in Processes Understanding and Designs of Constructed Wetlands Applied for Treatment of Various Wastewater Sources)
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33 pages, 2591 KiB  
Review
Benthic Foraminiferal Indices and Environmental Quality Assessment of Transitional Waters: A Review of Current Challenges and Future Research Perspectives
by Phoebe A. J. O’Brien, Irina Polovodova Asteman and Vincent M. P. Bouchet
Water 2021, 13(14), 1898; https://doi.org/10.3390/w13141898 - 8 Jul 2021
Cited by 31 | Viewed by 7536
Abstract
Transitional waters straddle the interface between marine and terrestrial biomes and, among others, include fjords, bays, lagoons, and estuaries. These coastal systems are essential for transport and manufacturing industries and suffer extensive anthropogenic exploitation of their ecosystem services for aquaculture and recreational activities. [...] Read more.
Transitional waters straddle the interface between marine and terrestrial biomes and, among others, include fjords, bays, lagoons, and estuaries. These coastal systems are essential for transport and manufacturing industries and suffer extensive anthropogenic exploitation of their ecosystem services for aquaculture and recreational activities. These activities can have negative effects on the local biota, necessitating investigation and regulation. As a result of this, EcoQS (ecological quality status) assessment has garnered great attention as an essential aspect of governmental bodies’ legislative decision-making process. Assessing EcoQS in transitional water ecosystems is problematic because these systems experience high natural variability and organic enrichment and often lack information about their pre-human impact, baseline, or “pristine” reference conditions, knowledge of which is essential to many commonly used assessment methods. Here, foraminifera can be used as environmental sentinels, providing ecological data such as diversity and sensitivity, which can be used as the basis for EcoQS assessment indices. Fossil shells of foraminifera can also provide a temporal aspect to ecosystem assessment, making it possible to obtain reference conditions from the study site itself. These foraminifera-based indices have been shown to correlate not only with various environmental stressors but also with the most common macrofaunal-based indices currently employed by bodies such as the Water Framework Directive (WFD). In this review, we firstly discuss the development of various foraminifera-based indices and address the challenge of how best to implement these synergistically to understand and regulate human environmental impact, particularly in transitional waters, which have historically suffered disproportionate levels of human impact or are difficult to assess with standard EcoQS methods. Further, we present some case studies to exemplify key issues and discuss potential solutions for those. Such key issues include, for example, the disparate performance of multiple indices applied to the same site and a proper assignment of EcoQS class boundaries (threshold values) for each index. Disparate aptitudes of indices to specific geomorphologic and hydrological regimes can be leveraged via the development of a site characteristics catalogue, which would enable the identification of the most appropriate index to apply, and the integration of multiple indices resulting in more representative EcoQS assessment in heterogenous transitional environments. In addition, the difficulty in assigning threshold values to systems without analogous unimpacted reference sites (a common issue among many transitional waters) can be overcome by recording EcoQS as an ecological quality ratio (EQR). Lastly, we evaluate the current status and future potential of an emerging field, genetic biomonitoring, focusing on how these new techniques can be used to increase the accuracy of EcoQS assessment in transitional systems by supplementing more established morphology-based methods. Full article
(This article belongs to the Special Issue Ecological Quality Status Assessment of Aquatic Ecosystems: New Methods and Perspectives for the Future)
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17 pages, 17428 KiB  
Article
Definition of the Operational Curves by Modification of the Affinity Laws to Improve the Simulation of PATs
by Carlos Andrés Macías Ávila, Francisco-Javier Sánchez-Romero, P. Amparo López-Jiménez and Modesto Pérez-Sánchez
Water 2021, 13(14), 1880; https://doi.org/10.3390/w13141880 - 6 Jul 2021
Cited by 20 | Viewed by 3333
Abstract
New technologies for water pressurized systems try to implement the introduction of strategies for the improvement of the sustainable indicators. One of these technologies is the implementation of pumps working as turbines. The use of these recovery machines was proposed some years ago, [...] Read more.
New technologies for water pressurized systems try to implement the introduction of strategies for the improvement of the sustainable indicators. One of these technologies is the implementation of pumps working as turbines. The use of these recovery machines was proposed some years ago, and the interest in this technology has increased over the last years. The simulation of these machines is necessary when analyzing pressurized water systems, or when optimization procedures are proposed for their management, great care must be taken. In these cases, the knowledge of the operation curves is crucial to reach accurate results. This study proposes different regression expressions to define three operational curves when the machines operate under variable rotational speed. These curves are the best efficiency head, the best power-head and the best power flow. The here proposed methods were compared with other five published methods. The comparison shows the proposed method was the best when it is compared with the rest of the published procedures, reducing the error values between 8 and 20%. Full article
(This article belongs to the Special Issue Hydraulic Dynamic Calculation and Simulation Ⅱ)
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24 pages, 2141 KiB  
Article
Advances in Egyptian Mediterranean Coast Climate Change Monitoring
by Matteo Gentilucci, Abdelraouf A. Moustafa, Fagr Kh. Abdel-Gawad, Samira R. Mansour, Maria Rosaria Coppola, Lidia Caserta, Sara Inglese, Gilberto Pambianchi and Giulia Guerriero
Water 2021, 13(13), 1870; https://doi.org/10.3390/w13131870 - 5 Jul 2021
Cited by 18 | Viewed by 5811
Abstract
This paper characterizes non-indigenous fish species (NIS) and analyses both atmospheric and sea surface temperatures for the Mediterranean coast of Egypt from 1991 to 2020, in relation to previous reports in the same areas. Taxonomical characterization depicts 47 NIS from the Suez Canal [...] Read more.
This paper characterizes non-indigenous fish species (NIS) and analyses both atmospheric and sea surface temperatures for the Mediterranean coast of Egypt from 1991 to 2020, in relation to previous reports in the same areas. Taxonomical characterization depicts 47 NIS from the Suez Canal (Lessepsian/alien) and 5 from the Atlantic provenance. GenBank accession number of the NIS mitochondrial gene, cytochrome oxidase 1, reproductive and commercial biodata, and a schematic Inkscape drawing for the most harmful Lessepsian species were reported. For sea surface temperatures (SST), an increase of 1.2 °C to 1.6 °C was observed using GIS software. The lack of linear correlation between annual air temperature and annual SST at the same detection points (Pearson r) could suggest a difference in submarine currents, whereas the Pettitt homogeneity test highlights a temperature breakpoint in 2005–2006 that may have favoured the settlement of non-indigenous fauna in the coastal sites of Damiette, El Arish, El Hammam, Alexandria, El Alamain, and Mersa Matruh, while there seems to be a breakpoint present in 2001 for El Sallum. This assessment of climate trends is in good agreement with the previous sightings of non-native fish species. New insights into the assessment of Egyptian coastal climate change are discussed. Full article
(This article belongs to the Special Issue Climate Impact on Sustainability of Aquatic Organisms)
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20 pages, 3036 KiB  
Article
Anomaly Detection Using a Sliding Window Technique and Data Imputation with Machine Learning for Hydrological Time Series
by Lattawit Kulanuwat, Chantana Chantrapornchai, Montri Maleewong, Papis Wongchaisuwat, Supaluk Wimala, Kanoksri Sarinnapakorn and Surajate Boonya-aroonnet
Water 2021, 13(13), 1862; https://doi.org/10.3390/w13131862 - 3 Jul 2021
Cited by 52 | Viewed by 15232
Abstract
Water level data obtained from telemetry stations typically contains large number of outliers. Anomaly detection and a data imputation are necessary steps in a data monitoring system. Anomaly data can be detected if its values lie outside of a normal pattern distribution. We [...] Read more.
Water level data obtained from telemetry stations typically contains large number of outliers. Anomaly detection and a data imputation are necessary steps in a data monitoring system. Anomaly data can be detected if its values lie outside of a normal pattern distribution. We developed a median-based statistical outlier detection approach using a sliding window technique. In order to fill anomalies, various interpolation techniques were considered. Our proposed framework exhibited promising results after evaluating with F1-score and root mean square error (RMSE) based on our artificially induced data points. The present system can also be easily applied to various patterns of hydrological time series with diverse choices of internal methods and fine-tuned parameters. Specifically, the Spline interpolation method yielded a superior performance on non-cyclical data while the long short-term memory (LSTM) outperformed other interpolation methods on a distinct tidal data pattern. Full article
(This article belongs to the Section Hydrology)
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16 pages, 460 KiB  
Review
Pollution Biomarkers in the Framework of Marine Biodiversity Conservation: State of Art and Perspectives
by Maria Giulia Lionetto, Roberto Caricato and Maria Elena Giordano
Water 2021, 13(13), 1847; https://doi.org/10.3390/w13131847 - 2 Jul 2021
Cited by 39 | Viewed by 7630
Abstract
Marine biodiversity is threatened by several anthropogenic pressures. Pollution deriving from the discharge of chemical contaminants in the sea represents one of the main threats to the marine environment, influencing the health of organisms, their ability to recover their homeostatic status, and in [...] Read more.
Marine biodiversity is threatened by several anthropogenic pressures. Pollution deriving from the discharge of chemical contaminants in the sea represents one of the main threats to the marine environment, influencing the health of organisms, their ability to recover their homeostatic status, and in turn endangering biodiversity. Molecular and cellular responses to chemical pollutants, known as biomarkers, are effect-based methodologies useful for detecting exposure and for assessing the effects of pollutants on biota in environmental monitoring. The present review analyzes and discusses the recent literature on the use of biomarkers in the framework of biodiversity conservation. The study shows that pollution biomarkers can be useful tools for monitoring and assessment of pollution threat to marine biodiversity, both in the environmental quality monitoring of protected areas and the assessment of the health status of species at risk. Moreover, key areas of the research that need further development are suggested, such as the development of omics-based biomarkers specifically addressed to conservation purposes and their validation in the field, the extension of the biomarker study to a wider number of endangered species, and the development of organic guidelines for the application of the biomarker approach in support to conservation policies and management. Full article
(This article belongs to the Special Issue Implementation of Biodiversity and Ecosystem Services in Marine Ecosystem Management)
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14 pages, 17557 KiB  
Article
Analysis of Characteristics of Hydrological and Meteorological Drought Evolution in Southwest China
by Han Tang, Tong Wen, Peng Shi, Simin Qu, Lanlan Zhao and Qiongfang Li
Water 2021, 13(13), 1846; https://doi.org/10.3390/w13131846 - 1 Jul 2021
Cited by 25 | Viewed by 4655
Abstract
Based on the data of 82 meteorological stations and six representative hydrological stations in four provinces in Southwest China (Guizhou, Sichuan, Yunnan, Chongqing), this paper uses standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) to analyze the spatial and temporal evolution [...] Read more.
Based on the data of 82 meteorological stations and six representative hydrological stations in four provinces in Southwest China (Guizhou, Sichuan, Yunnan, Chongqing), this paper uses standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) to analyze the spatial and temporal evolution characteristics of drought in the study area from 1968 to 2018. Combined with the Southwest monsoon index and historical drought data, the correlation of drought and the applicability of different drought indices were verified. The results show that: (1) SPEI-12 in Southwest China shows a downward trend from 1968 to 2018, with a linear trend rate of −0.074/10a, and SPEI-3 has a downward trend in four seasons, the maximum linear trend rate being −0.106/10a in autumn;(2) The change in SRI-12 and SRI-24 value directly reflected the decrease in SRI value, indicating that drought events are increasing in recent times, especially in the 21st century (3). Severe drought occurred in the south of Southwest China, as indicated by the increase of drought frequency in this area. The main reason for the variations in the frequency distribution of drought in Southwest China is the combined effect of the change of precipitation and evapotranspiration. (4) The correlation between hydrological drought index and disaster areas is stronger than the correlation between meteorological drought and disaster areas. Full article
(This article belongs to the Special Issue Human and Climate Impacts on Drought Dynamics and Vulnerability)
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15 pages, 4414 KiB  
Article
Assessment of Heavy Metal Pollution Levels in Sediments and of Ecological Risk by Quality Indices, Applying a Case Study: The Lower Danube River, Romania
by Valentina Andreea Calmuc, Madalina Calmuc, Maxim Arseni, Catalina Maria Topa, Mihaela Timofti, Adrian Burada, Catalina Iticescu and Lucian P. Georgescu
Water 2021, 13(13), 1801; https://doi.org/10.3390/w13131801 - 29 Jun 2021
Cited by 63 | Viewed by 5662
Abstract
It is a well–known fact that heavy metal pollution in sediments causes serious problems not only in the Danube basin, but also in the large and small adjacent river streams. A suitable method for assessing the level of heavy metals and their toxicity [...] Read more.
It is a well–known fact that heavy metal pollution in sediments causes serious problems not only in the Danube basin, but also in the large and small adjacent river streams. A suitable method for assessing the level of heavy metals and their toxicity in sediments is the calculation of pollution indices. The present research aims to assess heavy metal pollution in the Lower Danube surface sediments collected along the Danube course (between 180 and 60 km) up to the point where the Danube River flows into the Danube Delta Biosphere Reserve (a United Nations Educational, Scientific and Cultural Organization—UNESCO, protected area). In addition, this monitored area is one of the largest European hydrographic basins. Five heavy metals (Cd, Ni, Zn, Pb, Cu) were analyzed in two different seasons, i.e., the autumn of 2018 and the spring of 2019, using the Inductively Coupled Plasma Mass Spectrometry (ICP– MS) technique. Our assessment of heavy metal pollution revealed two correlated aspects: 1. a determination of the potential risks of heavy metals in sediments by calculating the Potential Ecological Risk Index (RI), and 2. an evaluation of the influence of anthropogenic activities on the level of heavy metal contamination in the surface sediments, using three specific pollution indices, namely, the Geo–Accumulation Index (Igeo), the Contamination Factor (CF), and the Pollution Load Index (PLI). The results of this pioneering research activity in the region highlighted the presence of moderate metal (Ni and Cd) pollution and a low potential ecological risk for the aquatic environment. Full article
(This article belongs to the Section Water Quality and Contamination)
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19 pages, 4142 KiB  
Article
Performance Assessment System for Energy Efficiency in Wastewater Systems
by Catarina Jorge, Maria do Céu Almeida and Dídia Covas
Water 2021, 13(13), 1807; https://doi.org/10.3390/w13131807 - 29 Jun 2021
Cited by 8 | Viewed by 3038
Abstract
Performance assessment is essential to effectively evaluate and monitor the activity of water utilities, support decision making, and encourage continuous improvement. Performance assessment systems (PAS), covering several service objectives and criteria, have been successfully applied in water supply and wastewater systems. Tailored approaches [...] Read more.
Performance assessment is essential to effectively evaluate and monitor the activity of water utilities, support decision making, and encourage continuous improvement. Performance assessment systems (PAS), covering several service objectives and criteria, have been successfully applied in water supply and wastewater systems. Tailored approaches focusing on the assessment of the energy use and efficiency in wastewater systems are still limited. This paper aims at the development and demonstration of a comprehensive PAS for energy efficiency, tailored for wastewater systems, incorporating criteria related to energy consumption, operation and maintenance (O&M) costs, and environmental impacts, such as untreated discharges and greenhouse gases emissions, among others. Management and control of excessive or undue inflows to these systems is specifically addressed by several novel criteria and metrics. The proposed PAS should be adapted by each utility to be aligned with the objectives of the organisation and with the implemented asset management strategy. The proposed approach and the resulting consolidated PAS are thoroughly described. Results from the application of the PAS to several Portuguese utilities are discussed. This PAS aims at contributing to a reliable and replicable process to assess energy efficiency in wastewater systems and to encourage a more rational energy management. Full article
(This article belongs to the Special Issue Infrastructure Asset Management of Urban Water Systems)
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21 pages, 6318 KiB  
Article
Exploring the Spatial Impact of Green Infrastructure on Urban Drainage Resilience
by Mayra Rodriguez, Guangtao Fu, David Butler, Zhiguo Yuan and Keshab Sharma
Water 2021, 13(13), 1789; https://doi.org/10.3390/w13131789 - 28 Jun 2021
Cited by 24 | Viewed by 5665
Abstract
This paper explores the spatial impact of green infrastructure (GI) location on the resilience of urban drainage systems by the application of exploratory spatial data analysis (ESDA). A framework that integrates resilience assessment, location sensitivity analysis and ESDA is presented and applied to [...] Read more.
This paper explores the spatial impact of green infrastructure (GI) location on the resilience of urban drainage systems by the application of exploratory spatial data analysis (ESDA). A framework that integrates resilience assessment, location sensitivity analysis and ESDA is presented and applied to an urban catchment in the United Kingdom. Three types of GI, namely a bioretention cell, permeable pavement, and green roof, are evaluated separately and simultaneously. Resilience is assessed using stress-strain tests, which measure the system performance based on the magnitude and duration of sewer flooding and combined sewer overflows. Based on the results of a location sensitivity analysis, ESDA is applied to determine if there is spatial autocorrelation, spatial clusters, and spatial outliers. Results show a stronger spatial dependency using sewer flooding indicators. Different GI measures present differences in spatial autocorrelation and spatial cluster results, highlighting the differences in their underlying mechanisms. The finding of conflicting spatial clusters indicates that there are trade-offs in the placement of GI in certain locations. The proposed framework can be used as a tool for GI spatial planning, helping in the development of a systematic approach for resilience-performance orientated GI design and planning. Full article
(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)
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14 pages, 4632 KiB  
Article
3D-CNN-Based Sky Image Feature Extraction for Short-Term Global Horizontal Irradiance Forecasting
by Hao Yang, Long Wang, Chao Huang and Xiong Luo
Water 2021, 13(13), 1773; https://doi.org/10.3390/w13131773 - 27 Jun 2021
Cited by 18 | Viewed by 3969
Abstract
The instability and variability of solar irradiance induces great challenges for the management of photovoltaic water pumping systems. Accurate global horizontal irradiance (GHI) forecasting is a promising technique to solve this problem. To improve short-term GHI forecasting accuracy, ground-based sky image is valuable [...] Read more.
The instability and variability of solar irradiance induces great challenges for the management of photovoltaic water pumping systems. Accurate global horizontal irradiance (GHI) forecasting is a promising technique to solve this problem. To improve short-term GHI forecasting accuracy, ground-based sky image is valuable due to its correlation with solar generation. In previous studies, great efforts have been made to extract numerical features from sky image for data-driven solar irradiance forecasting methods, e.g., based on pixel-value color information, and based on the cloud motion detection method. In this work, we propose a novel feature extracting method for GHI forecasting that a three-dimensional (3D) convolutional neural network (CNN) is developed to extract features from sky images with efficient training strategies. Popular machine learning algorithms are introduced as GHI forecasting models and corresponding forecasting accuracy is fully explored with different input features on a large dataset. The numerical experiment illustrates that the minimum average root mean square error (RMSE) of 62 W/m2 is achieved by the proposed method with 15.2% improvement in Skill score against baseline forecasting method. Full article
(This article belongs to the Special Issue New Perspectives in Agricultural Water Management)
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16 pages, 3102 KiB  
Article
Water Footprint and Virtual Water Trade of Maize in the Province of Buenos Aires, Argentina
by Maria Macarena Arrien, Maite M. Aldaya and Corina Iris Rodriguez
Water 2021, 13(13), 1769; https://doi.org/10.3390/w13131769 - 26 Jun 2021
Cited by 17 | Viewed by 5776
Abstract
Agriculture is the largest fresh water consuming sector, and maize is the most produced and consumed crop worldwide. The water footprint (WF) methodology quantifies and evaluates the water volumes consumed and polluted by a given crop, as well as its impacts. In this [...] Read more.
Agriculture is the largest fresh water consuming sector, and maize is the most produced and consumed crop worldwide. The water footprint (WF) methodology quantifies and evaluates the water volumes consumed and polluted by a given crop, as well as its impacts. In this work, we quantified for the first time the green WF (soil water from precipitation that is evapotranspired) and the green virtual water exports of maize from Buenos Aires province, Argentina, during 2016–2017, due to the relevance of this region in the world maize trade. Furthermore, at local level, we quantified the green, blue (evapotranspired irrigation), and grey (volume of water needed to assimilate a pollution load) WF of maize in a pilot basin. The green WF of maize in the province of Buenos Aires ranged between 170 and 730 m3/ton, with the highest values in the south following a pattern of yields. The contribution of this province in terms of green virtual water to the international maize trade reached 2213 hm3/year, allowing some water-scarce nations to ensure water and water-dependent food security and avoid further environmental impacts related to water. At the Napaleofú basin scale, the total WF of rainfed maize was 358 m3/ton (89% green and 11% grey) and 388 m3/ton (58% green, 25% blue, and 17% grey) for the irrigated crop, showing that there is not only a green WF behind the exported maize, but also a Nitrogen-related grey WF. Full article
(This article belongs to the Special Issue Water Footprint and Virtual Water Trade Approaches: Applications to the Water-Energy-Food-Land Nexus in a Context of Climate Change)
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13 pages, 4295 KiB  
Article
Analysis of Virtual Water Trade Flow and Driving Factors in the European Union
by Tianbo Fu, Changxin Xu and Xinyi Huang
Water 2021, 13(13), 1771; https://doi.org/10.3390/w13131771 - 26 Jun 2021
Cited by 14 | Viewed by 5188
Abstract
The inefficient application of water resources has become an urgent problem restricting the world’s sustainable development. Virtual Water Trade opens a new perspective on improving water resource utilization efficiency. Based on a multi-regional input–output model and the logarithmic mean Divisia index, the virtual [...] Read more.
The inefficient application of water resources has become an urgent problem restricting the world’s sustainable development. Virtual Water Trade opens a new perspective on improving water resource utilization efficiency. Based on a multi-regional input–output model and the logarithmic mean Divisia index, the virtual water flows between 2000–2014 in 43 countries and regions have been evaluated, and the driving forces of changes in virtual water flows for the European Union were revealed. During the study period, the total amount of virtual water flow continued to increase. The United Kingdom is a net virtual water importer that depends on the European Union significantly. There was a large amount of virtual water flow from the European Union to the United States during 2000–2012. However, China gradually seized the share of virtual water from European Union exports after 2012. Economic effects and virtual water intensity effects are the most significant drivers of virtual water flows. The difference is that the economic effect positively drives virtual water flows, while the virtual water intensity effect negatively influences. The results reveal the nature of the United Kingdom in the virtual water trade and can provide post-Brexit recommendations. Full article
(This article belongs to the Section Water Use and Scarcity)
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24 pages, 6453 KiB  
Article
Imaging the Structure and the Saltwater Intrusion Extent of the Luy River Coastal Aquifer (Binh Thuan, Vietnam) Using Electrical Resistivity Tomography
by Diep Cong-Thi, Linh Pham Dieu, Robin Thibaut, Marieke Paepen, Huu Hieu Ho, Frédéric Nguyen and Thomas Hermans
Water 2021, 13(13), 1743; https://doi.org/10.3390/w13131743 - 24 Jun 2021
Cited by 20 | Viewed by 5264
Abstract
With the growing population and the adverse effects of climate change, the pressure on coastal aquifers is increasing, leading to a larger risk of saltwater intrusion (SI). SI is often complex and difficult to characterize from well data only. In this context, electrical [...] Read more.
With the growing population and the adverse effects of climate change, the pressure on coastal aquifers is increasing, leading to a larger risk of saltwater intrusion (SI). SI is often complex and difficult to characterize from well data only. In this context, electrical resistivity tomography (ERT) can provide high-resolution qualitative information on the lateral and vertical distribution of salinity. However, the quantitative interpretation of ERT remains difficult because of the uncertainty of petrophysical relationships, the limitations of inversion, and the heterogeneity of aquifers. In this contribution, we propose a methodology for the semiquantitative interpretation of ERT when colocated well data are not available. We first use existing wells to identify freshwater zones and characterize the resistivity response of clayey deposits. Then, we approximate the formation factor from water samples collected in the vicinity of ERT data to derive a resistivity threshold to interpret the saline boundary. We applied the methodology in the shallow aquifers of the Luy River in the Binh Thuan province, Vietnam, where water resources are under pressure due to agricultural, aquacultural, and industrial production. Twenty-one ERT profiles were collected and revealed a much larger intrusion zone, compared to the previous study. Saltwater is present in lowland areas of the left bank over almost the whole thickness of the aquifer, while the right bank is constituted of sand dunes that are filled with freshwater. At a larger distance from the sea, a complex distribution between fresh and saltwater is observed. Our methodology could be applied to other heterogeneous aquifers in the absence of a dense monitoring network. Full article
(This article belongs to the Special Issue Seawater Intrusion into Coastal Aquifers)
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34 pages, 17622 KiB  
Review
Coastal Structures as Beach Erosion Control and Sea Level Rise Adaptation in Malaysia: A Review
by Ahmad Hadi Mohamed Rashidi, Mohamad Hidayat Jamal, Mohamad Zaki Hassan, Siti Salihah Mohd Sendek, Syazana Lyana Mohd Sopie and Mohd Radzi Abd Hamid
Water 2021, 13(13), 1741; https://doi.org/10.3390/w13131741 - 23 Jun 2021
Cited by 59 | Viewed by 35475
Abstract
The shoreline of Malaysia is exposed to threats of coastal erosion and a rise of sea level. The National Coastal Erosion Study, 2015 reported that 15% of an 8840 km shoreline is currently eroding, where one-third of those falls under the critical and [...] Read more.
The shoreline of Malaysia is exposed to threats of coastal erosion and a rise of sea level. The National Coastal Erosion Study, 2015 reported that 15% of an 8840 km shoreline is currently eroding, where one-third of those falls under the critical and significant categories that require structural protection. The Study of Sea Level Rise in Malaysia, 2017 presented a sea-level increase of 0.67–0.74 mm on average yearly. This study reviewed selected coastal protection structures along the shoreline of Malaysia as an erosion control and sea-level rise adaptation based on coastal management strategies. Hard structures such as rock revetment and breakwater are commonly used as erosion protection systems in the “hold the line” strategy. Increased platform level of seawalls and earth bunds, considered as an “adaptation” approach, are effective in erosion protection and are adaptive to sea-level rise. Mangrove replanting is suitable as a “limited intervention” approach in minimizing the long-term impact of both threats. However, offshore breakwater, groyne, and geotextile tubes are solely for protection purposes and are not as effective for sea-level rise adaptation. As the sea level is continuously increasing, their function as coastal protection will also become less effective. In summary, this comprehensive review on coastal protection in Malaysia will benefit the related agencies on the future assessment. Full article
(This article belongs to the Special Issue Impact of Climate Change on Coasts and Coastal Structures)
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37 pages, 6224 KiB  
Review
IoT Based Smart Water Quality Monitoring: Recent Techniques, Trends and Challenges for Domestic Applications
by Farmanullah Jan, Nasro Min-Allah and Dilek Düştegör
Water 2021, 13(13), 1729; https://doi.org/10.3390/w13131729 - 22 Jun 2021
Cited by 177 | Viewed by 58325
Abstract
Safe water is becoming a scarce resource, due to the combined effects of increased population, pollution, and climate changes. Water quality monitoring is thus paramount, especially for domestic water. Traditionally used laboratory-based testing approaches are manual, costly, time consuming, and lack real-time feedback. [...] Read more.
Safe water is becoming a scarce resource, due to the combined effects of increased population, pollution, and climate changes. Water quality monitoring is thus paramount, especially for domestic water. Traditionally used laboratory-based testing approaches are manual, costly, time consuming, and lack real-time feedback. Recently developed systems utilizing wireless sensor network (WSN) technology have reported weaknesses in energy management, data security, and communication coverage. Due to the recent advances in Internet-of-Things (IoT) that can be applied in the development of more efficient, secure, and cheaper systems with real-time capabilities, we present here a survey aimed at summarizing the current state of the art regarding IoT based smart water quality monitoring systems (IoT-WQMS) especially dedicated for domestic applications. In brief, this study probes into common water-quality monitoring (WQM) parameters, their safe-limits for drinking water, related smart sensors, critical review, and ratification of contemporary IoT-WQMS via a proposed empirical metric, analysis, and discussion and, finally, design recommendations for an efficient system. No doubt, this study will benefit the developing field of smart homes, offices, and cities. Full article
(This article belongs to the Special Issue Water Quality Management in Water Distribution Networks)
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20 pages, 4062 KiB  
Article
Identifying Storm Hotspots and the Most Unsettled Areas in Barcelona by Analysing Significant Rainfall Episodes from 2013 to 2018
by Laura Esbrí, Tomeu Rigo, María Carmen Llasat and Blanca Aznar
Water 2021, 13(13), 1730; https://doi.org/10.3390/w13131730 - 22 Jun 2021
Cited by 5 | Viewed by 3343
Abstract
Urban floods repeatedly threaten Barcelona, damaging the city infrastructure and endangering the safety of the population. The urban planning of the city, the socioeconomic distribution, its topography, and the characteristics of precipitation systems translate into these flood events having a heterogeneous effect across [...] Read more.
Urban floods repeatedly threaten Barcelona, damaging the city infrastructure and endangering the safety of the population. The urban planning of the city, the socioeconomic distribution, its topography, and the characteristics of precipitation systems translate into these flood events having a heterogeneous effect across the city. It means that the coping capacity has a strong dependence on local factors that must be considered when management plans are developed by the municipality. This work aims to contribute to the better knowledge of precipitation structures associated with heavy rainfall events and floods in Barcelona based on radar data and an urban rain gauge network. Radar data have been provided by the Meteorological Service of Catalonia (SMC), while precipitation data, impact data, and early warnings, have been provided by Barcelona Cicle de l’Aigua S.A. (BCASA), for the period 2013–2018. A new radar-based methodology has been developed to identify convective rainfall structures from radar reflectivity volumes (CAPPI and TOP products) to make the analysis easier. The high computing speed of the procedure allows efficient analysis of a large set of convective cells without scarifying temporal resolution of radar data. Both rainfall fields (radar and rain gauge, respectively) have been compared. Then through the identified rainfall convective structures, thunderstorm hotspots have been identified. Considering an alert indicator from BCASA and the reported incidents, episodes with the highest impact have been analysed in depth. Results show 207 significant rainfall episodes in the ROI for the six years, which are mainly concentrated between September and November. The fact that significant episodes are usually produced by highly convective rain corroborates the advantage of using radar images as a tool to detect any maxima even when no rain gauge is there. In 64 of the episodes, the level of pre-alert was achieved with a maximum frequency between August and September. The proposed algorithm shows more than 8000 centroids of convective cells from 189 cases. Whilst maximum surface reflectivity over 45 dBZ is more prone to occur near the coastline, the centroids of storm cells tend to concentrate more inland. The final objective is to improve the actions taken by the organisation responsible for managing urban floods, which have seen Barcelona recognised as a model city for flood resilience by the United Nations. Full article
(This article belongs to the Special Issue Management of Hydro-Meteorological Hazards)
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27 pages, 1570 KiB  
Review
Current Progress on Marine Microplastics Pollution Research: A Review on Pollution Occurrence, Detection, and Environmental Effects
by Fei-Fei Liu, Su-Chun Wang, Zhi-Lin Zhu and Guang-Zhou Liu
Water 2021, 13(12), 1713; https://doi.org/10.3390/w13121713 - 21 Jun 2021
Cited by 22 | Viewed by 10582
Abstract
Recently, microplastics pollution has attracted much attention in the environmental field, as researchers have found traces of microplastics in both marine and terrestrial ecological environments. Here, we reviewed and discussed the current progress on microplastics pollution in the marine environment from three main [...] Read more.
Recently, microplastics pollution has attracted much attention in the environmental field, as researchers have found traces of microplastics in both marine and terrestrial ecological environments. Here, we reviewed and discussed the current progress on microplastics pollution in the marine environment from three main aspects including their identification and qualification methods, source and distribution, and fate and toxicity in a marine ecosystem. Microplastics in the marine environment originate from a variety of sources and distribute broadly all around the world, but their quantitative information is still lacking. Up to now, there have been no adequate and standard methods to identify and quantify the various types of microplastics, which need to be developed and unified. The fate of microplastics in the environment is particularly important as they may be transferred or accumulated in the biological chain. Meanwhile, microplastics may have a high adsorption capacity to pollutants, which is the basic research to further study their fate and joint toxicity in the environment. Therefore, all the findings are expected to fill the knowledge gaps in microplastics pollution and promote the development of relative regulations. Full article
(This article belongs to the Special Issue Microplastics Pollution in Marine Environment)
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21 pages, 2718 KiB  
Article
Note on the Application of Transient Wave Packets for Wave–Ice Interaction Experiments
by Marco Klein, Moritz Hartmann and Franz von Bock und Polach
Water 2021, 13(12), 1699; https://doi.org/10.3390/w13121699 - 19 Jun 2021
Cited by 9 | Viewed by 3316
Abstract
This paper presents the transient wave packet (TWP) technique as an efficient method for wave–ice interaction experiments. TWPs are deterministic wave groups, where both the amplitude spectrum and the associated phases are tailor-made and manipulated, being well established for efficient wave–structure interaction experiments. [...] Read more.
This paper presents the transient wave packet (TWP) technique as an efficient method for wave–ice interaction experiments. TWPs are deterministic wave groups, where both the amplitude spectrum and the associated phases are tailor-made and manipulated, being well established for efficient wave–structure interaction experiments. One major benefit of TWPs is the possibility to determine the response amplitude operator (RAO) of a structure in a single test run compared to the classical approach by investigating regular waves of different wave lengths. Thus, applying TWPs for wave–ice interaction offers the determination of the RAO of the ice at specific locations. In this context, the determination of RAO means that the ice characteristics in terms of wave damping over a wide frequency range are obtained. Besides this, the wave dispersion of the underlying wave components of the TWP can be additionally investigated between the specific locations with the same single test run. For the purpose of this study, experiments in an ice tank, capable of generating tailored waves, were performed with a solid ice sheet. Besides the generation of one TWP, regular waves of different wave lengths were generated as a reference to validate the TWP results for specific wave periods. It is shown that the TWP technique is not only applicable for wave–ice interaction investigations, but is also an efficient alternative to investigations with regular waves. Full article
(This article belongs to the Special Issue The Occurrence, Physics and Impact of Wave–Ice Interaction)
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18 pages, 9544 KiB  
Article
The Story of a Steep River: Causes and Effects of the Flash Flood on 24 July 2017 in Western Norway
by Adina Moraru, Michal Pavlíček, Oddbjørn Bruland and Nils Rüther
Water 2021, 13(12), 1688; https://doi.org/10.3390/w13121688 - 18 Jun 2021
Cited by 8 | Viewed by 5305
Abstract
Flash floods can cause great geomorphological changes in ephemeral fluvial systems and result in particularly severe damages for the unprepared population exposed to it. The flash flood in the Storelva river in Utvik (western Norway) on 24 July 2017 was witnessed and documented. [...] Read more.
Flash floods can cause great geomorphological changes in ephemeral fluvial systems and result in particularly severe damages for the unprepared population exposed to it. The flash flood in the Storelva river in Utvik (western Norway) on 24 July 2017 was witnessed and documented. This study assessed the causes and effects of the 2017 flood and provides valuable information for the calibration and validation of future modelling studies. The flooded area at peak discharge, maximum wetted and dry areas during the entire event, critical points and main flow paths were reconstructed using on-site and post-event (i) visual documentation, such as photographs and videos, and (ii) aerial surveying, such as orthophotographs and laser scanning, of the lowermost reach. The steep longitudinal slope together with the loose material forming the valley and riverbed contributed to a large amount of sediment transport during this extreme event. Steep rivers such as the Storelva river have very short response times to extreme hydrologic conditions, which calls for exhaustive monitoring and data collection in case of future events, as well as modelling tools that can emulate the hydro-morphodynamics observed during events such as the 2017 flash flood. Full article
(This article belongs to the Special Issue Recent Advances in Flood Hazard and Risk Science)
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51 pages, 4503 KiB  
Article
An In-Depth Analysis of Physical Blue and Green Water Scarcity in Agriculture in Terms of Causes and Events and Perceived Amenability to Economic Interpretation
by Kalomoira Zisopoulou and Dionysia Panagoulia
Water 2021, 13(12), 1693; https://doi.org/10.3390/w13121693 - 18 Jun 2021
Cited by 23 | Viewed by 14377
Abstract
An analytical review of physical blue and green water scarcity in terms of agricultural use, and its amenability to economic interpretation, is presented, employing more than 600 references. The main definitions and classifications involved and information about reserves and resources are critically analyzed, [...] Read more.
An analytical review of physical blue and green water scarcity in terms of agricultural use, and its amenability to economic interpretation, is presented, employing more than 600 references. The main definitions and classifications involved and information about reserves and resources are critically analyzed, blue and green water scarcity are examined along with their interchange, while their causal connection with climate in general is analyzed along with the particular instances of Europe, Africa, Asia and the WANA region. The role of teleconnections and evaporation/moisture import-export is examined as forms of action at a distance. The human intervention scarcity driver is examined extensively in terms of land use land cover change (LULCC), as well as population increase. The discussion deals with following critical problems: green and blue water availability, inadequate accessibility, blue water loss, unevenly distributed precipitation, climate uncertainty and country level over global level precedence. The conclusion singles out, among others, problems emerging from the inter-relationship of physical variables and the difficulty to translate them into economic instrumental variables, as well as the lack of imbedding uncertainty in the underlying physical theory due to the fact that country level measurements are not methodically assumed to be the basic building block of regional and global water scarcity. Full article
(This article belongs to the Special Issue The Economic Role of Water under Scarcity and Sustainability Constraints)
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25 pages, 4147 KiB  
Article
Land Use Change Influences Ecosystem Function in Headwater Streams of the Lowland Amazon Basin
by Kathi Jo Jankowski, Linda A. Deegan, Christopher Neill, Hillary L. Sullivan, Paulo Ilha, Leonardo Maracahipes-Santos, Nubia Marques and Marcia N. Macedo
Water 2021, 13(12), 1667; https://doi.org/10.3390/w13121667 - 15 Jun 2021
Cited by 10 | Viewed by 5386
Abstract
Intensive agriculture alters headwater streams, but our understanding of its effects is limited in tropical regions where rates of agricultural expansion and intensification are currently greatest. Riparian forest protections are an important conservation tool, but whether they provide adequate protection of stream function [...] Read more.
Intensive agriculture alters headwater streams, but our understanding of its effects is limited in tropical regions where rates of agricultural expansion and intensification are currently greatest. Riparian forest protections are an important conservation tool, but whether they provide adequate protection of stream function in these areas of rapid tropical agricultural development has not been well studied. To address these gaps, we conducted a study in the lowland Brazilian Amazon, an area undergoing rapid cropland expansion, to assess the effects of land use change on organic matter dynamics (OM), ecosystem metabolism, and nutrient concentrations and uptake (nitrate and phosphate) in 11 first order streams draining forested (n = 4) or cropland (n = 7) watersheds with intact riparian forests. We found that streams had similar terrestrial litter inputs, but OM biomass was lower in cropland streams. Gross primary productivity was low and not different between land uses, but ecosystem respiration and net ecosystem production showed greater seasonality in cropland streams. Although we found no difference in stream concentrations of dissolved nutrients, phosphate uptake exceeded nitrate uptake in all streams and was higher in cropland than forested streams. This indicates that streams will be more retentive of phosphorus than nitrogen and that if fertilizer nitrogen reaches streams, it will be exported in stream networks. Overall, we found relatively subtle differences in stream function, indicating that riparian buffers have thus far provided protection against major functional shifts seen in other systems. However, the changes we did observe were linked to watershed scale shifts in hydrology, water temperature, and light availability resulting from watershed deforestation. This has implications for the conservation of tens of thousands of stream kilometers across the expanding Amazon cropland region. Full article
(This article belongs to the Special Issue Tradeoffs among Food Production, Forests, and Water Resources in Tropical Agricultural Frontiers)
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24 pages, 4322 KiB  
Article
Development of a Multi-Methodological Approach to Support the Management of Water Supply Systems
by Wanderbeg C. de Araujo, Karla P. Oliveira-Esquerre and Oz Sahin
Water 2021, 13(12), 1655; https://doi.org/10.3390/w13121655 - 13 Jun 2021
Cited by 2 | Viewed by 3793
Abstract
The benefits provided by a model of system dynamics are directly related to its correct construction. One of the main challenges in the process of building such models is that they must be able to effectively represent a specific problematic situation. Thus, the [...] Read more.
The benefits provided by a model of system dynamics are directly related to its correct construction. One of the main challenges in the process of building such models is that they must be able to effectively represent a specific problematic situation. Thus, the main objective of this study is to develop a multi-methodological approach, adapting the problem structuring method of strategic options development and analysis (SODA) in the initial stage of the system dynamics (SD) model. The role of each of them clearly represents the contribution of this study: the SODA in the structuring (representation) phase of the problem and proposition of alternatives and the SD in the evaluation phase of these alternatives. To illustrate its application, the multimethodological approach developed was used to simulate scenarios considering management strategies, and the various variables affecting a water supply system, including population growth, in order to evaluate more “assertive” water management strategy(s) that could have been adopted to address the water crisis (2012–2017) and analysis future scenarios. The results show that, based on the vision of specialists with enough experience for the case studied, it was possible to structure the problem, and therefore propose a set of strategies (alternatives), which were: water loss control, wastewater reuse, application of more efficient tariffs to reduce water waste, inter-basin water transfer, and awareness regarding the use of water resources. After the survey of alternatives, scenarios were simulated considering these water management strategies. Simulation results showed that actions taken on the demand side would only be effective for a short period of water scarcity, (for example, the impact of the scarcity-based tariff on water consumption reduction). For severe drought scenarios and with a water producing system heavily dependent on rainfall, such action would no longer be efficient. However, water supply management-oriented strategies, e.g., inter-basin water transfers (PISF) and wastewater reuse, are highly effective in securing water supply and preventing water supply collapse in the region. The development of this multi-methodological approach is expected to be useful to support managers in the decision-making and implementation of water management strategies. Full article
(This article belongs to the Special Issue System Dynamics Modelling for Water–Energy–Climate Nexus)
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17 pages, 4968 KiB  
Article
An Effective Water Body Extraction Method with New Water Index for Sentinel-2 Imagery
by Wei Jiang, Yuan Ni, Zhiguo Pang, Xiaotao Li, Hongrun Ju, Guojin He, Juan Lv, Kun Yang, June Fu and Xiangdong Qin
Water 2021, 13(12), 1647; https://doi.org/10.3390/w13121647 - 11 Jun 2021
Cited by 80 | Viewed by 17875
Abstract
Surface water bodies, such as rivers, lakes, and reservoirs, play an irreplaceable role in global ecosystems and climate systems. Sentinel-2 imagery provides new high-resolution satellite remote sensing data. Based on the analysis of the spectral characteristics of the Sentinel-2 satellite, a novel water [...] Read more.
Surface water bodies, such as rivers, lakes, and reservoirs, play an irreplaceable role in global ecosystems and climate systems. Sentinel-2 imagery provides new high-resolution satellite remote sensing data. Based on the analysis of the spectral characteristics of the Sentinel-2 satellite, a novel water index called the Sentinel-2 water index (SWI) that is based on the vegetation-sensitive red-edge band (Band 5) and shortwave infrared (Band 11) bands was developed. Four representative water body types, namely, Taihu Lake, Yangtze River, Chaka Salt Lake, and Chain Lake, were selected as study areas to conduct a water body extraction performance comparison with the normalized difference water index (NDWI). We found that (1) the contrast value of the SWI was larger than that of the NDWI in terms of various water body types, including purer water, turbid water, salt water, and floating ice, which suggested that the SWI could achieve better enhancement performance for water bodies. (2) An effective water body extraction method was proposed by integrating the SWI and Otsu algorithm, which could accurately extract various water body types with high overall accuracy. (3) The method effectively extracted large water bodies and wide river channels by suppressing shadow noise in urban areas. Our results suggested that the novel method can achieve efficient water body extraction for rapidly and accurately extracting various water bodies from Sentinel-2 data and the novel method has application potential for larger-scale surface water mapping. Full article
(This article belongs to the Special Issue Understanding Surface Water Dynamics Based on Multisource Remote Sensing Data)
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15 pages, 3383 KiB  
Article
Fluoride Polluted Groundwaters in Calabria Region (Southern Italy): Natural Source and Remediation
by Ilaria Fuoco, Carmine Apollaro, Alessandra Criscuoli, Rosanna De Rosa, Svetlozar Velizarov and Alberto Figoli
Water 2021, 13(12), 1626; https://doi.org/10.3390/w13121626 - 9 Jun 2021
Cited by 16 | Viewed by 4022
Abstract
Excessive ingestion of fluoride through the consumption of F−-rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical [...] Read more.
Excessive ingestion of fluoride through the consumption of F−-rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical characterization was performed to define the source of natural pollution of two groundwaters (samples Pc and Bg) coming from deep crystalline aquifers located in the Calabria region (southern Italy) and to define and optimize the most appropriate water treatment strategy. The samples were classified as a F− enriched NaHCO3 type of water. In particular, the F− concentrations observed were 30 mg/L and 8.9 mg/L for the Pc and Bg samples, respectively. Based on the acquired geochemical characterization knowledge, the groundwaters were treated by two thin-film composite NF membranes, namely SPR 10113 and SPR 10114 which have so far not been used for water defluoridation. It was found that the SPR 10114 membrane was able to guarantee water permeates with F− contents lower than the threshold value of 1.5 mg/L for both treated waters, whereas the fluoride content remained above the threshold value when the Pc sample was treated using the SPR 10113 membrane. The obtained permeates were characterized by a low ionic load and were not suitable for long-term consumption as drinking water. However, all of the produced waters did not need any further re-mineralizing processes for agricultural irrigation or other purposes. Full article
(This article belongs to the Special Issue Emerging Integrated Processes for Sustainable Water-Energy-Materials-Food Nexus)
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22 pages, 4345 KiB  
Article
Flood Stage Forecasting Using Machine-Learning Methods: A Case Study on the Parma River (Italy)
by Susanna Dazzi, Renato Vacondio and Paolo Mignosa
Water 2021, 13(12), 1612; https://doi.org/10.3390/w13121612 - 8 Jun 2021
Cited by 65 | Viewed by 5448
Abstract
Real-time river flood forecasting models can be useful for issuing flood alerts and reducing or preventing inundations. To this end, machine-learning (ML) methods are becoming increasingly popular thanks to their low computational requirements and to their reliance on observed data only. This work [...] Read more.
Real-time river flood forecasting models can be useful for issuing flood alerts and reducing or preventing inundations. To this end, machine-learning (ML) methods are becoming increasingly popular thanks to their low computational requirements and to their reliance on observed data only. This work aimed to evaluate the ML models’ capability of predicting flood stages at a critical gauge station, using mainly upstream stage observations, though downstream levels should also be included to consider backwater, if present. The case study selected for this analysis was the lower stretch of the Parma River (Italy), and the forecast horizon was extended up to 9 h. The performances of three ML algorithms, namely Support Vector Regression (SVR), MultiLayer Perceptron (MLP), and Long Short-term Memory (LSTM), were compared herein in terms of accuracy and computational time. Up to 6 h ahead, all models provided sufficiently accurate predictions for practical purposes (e.g., Root Mean Square Error < 15 cm, and Nash-Sutcliffe Efficiency coefficient > 0.99), while peak levels were poorly predicted for longer lead times. Moreover, the results suggest that the LSTM model, despite requiring the longest training time, is the most robust and accurate in predicting peak values, and it should be preferred for setting up an operational forecasting system. Full article
(This article belongs to the Special Issue The Application of Artificial Intelligence in Hydrology)
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22 pages, 9329 KiB  
Article
Enhancing the Resilience of the Management of Water Resources in the Agricultural Supply Chain
by Wenping Xu, Zhi Zhong, David Proverbs, Shu Xiong and Yuan Zhang
Water 2021, 13(12), 1619; https://doi.org/10.3390/w13121619 - 8 Jun 2021
Cited by 19 | Viewed by 5505
Abstract
Due to population growth and human activities, water shortages have become an increasingly serious concern in recent years. The agri-food industry is the largest water-consuming industry among all industries, and various efforts have been made to reduce the loss of water in the [...] Read more.
Due to population growth and human activities, water shortages have become an increasingly serious concern in recent years. The agri-food industry is the largest water-consuming industry among all industries, and various efforts have been made to reduce the loss of water in the agricultural supply chain. Improving the resilience of water resource management is a key measure to reduce the risks in the agricultural supply chain. This study aims to identify the factors affecting the resilience of water management in the agricultural supply chain and to help manage the risks related to water resources use. A total of 14 factors are selected from five dimensions of society, economy, environment, institution, and crop characteristics, and an index institution is constructed. This was used to determine the level and importance of each factor. Data were collected through a questionnaire survey involving 28 experts from the agricultural industry in Northwest China, as well as a thorough literature analysis and interactions with experts. Using a combination of an interpretative structural model (ISM) and an analytical network process (ANP), a hierarchical structure model was developed, composed of direct factors, indirect factors, and basic factors. The results show that the selection of agricultural products, the establishment of a water audit control institution, the recycling of wastewater, and the investment in water-saving technologies are the main factors affecting the resilience of water resources management in the agricultural supply chain. These findings provide useful guidance for practitioners involved in the management of water resources in agricultural supply chains. These results are expected to contribute to the sustainable management and strategic deployment of water by agricultural supply chain stakeholders. Full article
(This article belongs to the Special Issue Water Allocation in Rural Area: Economic Influences and Better Management II)
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26 pages, 8569 KiB  
Article
Assessment of Complex Terminal Groundwater Aquifer for Different Use of Oued Souf Valley (Algeria) Using Multivariate Statistical Methods, Geostatistical Modeling, and Water Quality Index
by Ayoub Barkat, Foued Bouaicha, Oualid Bouteraa, Tamás Mester, Behnam Ata, Dániel Balla, Zakaria Rahal and György Szabó
Water 2021, 13(11), 1609; https://doi.org/10.3390/w13111609 - 7 Jun 2021
Cited by 40 | Viewed by 5342
Abstract
This research aims to assess the hydrogeochemical evolution of the groundwater in Oued souf valley for drinking and irrigation purposes. To achieve this, 49 groundwater samples from the complex terminal were examined and treated concurrently with multivariate statistical methods, geostatistical modeling and the [...] Read more.
This research aims to assess the hydrogeochemical evolution of the groundwater in Oued souf valley for drinking and irrigation purposes. To achieve this, 49 groundwater samples from the complex terminal were examined and treated concurrently with multivariate statistical methods, geostatistical modeling and the WQI (water quality index). Focusing on the physico-chemical parameters, Q mode clustering analysis detected four major water groups, where the mineralization augmented from group 1 to group 4. The hydro-chemical type was the same, Ca-Mg-Cl-SO4 for all the groups. Calcite, dolomite, anhydrite, and gypsum would be the dominant reactions with the undersaturation of evaporates minerals, based on geochemical modeling, while the carbonate minerals are precipitating. Geostatistical analysis using ordinary Kriging demonstrated the exponential semi-variogram model fitted for EC (electrical conductivity), Ca2+ (calcium), Mg2+ (magnesium), K+ (potassium), HCO3− (bicarbonate), Cl− (chloride), and SO42− (sulfate). At the same time, the rational quadratic model was the best-fitted semi-variogram model for Na+ (sodium) and NO3− (nitrate). EC, SO42−, and NO3− have a strong spatial structure, while Ca2+, Na+, K+, and HCO3− have a moderate spatial structure. Moreover, there was a weak spatial structure for Mg2+ and Cl−. The WQI shows that CT (complex terminal groundwater aquifers) are not suitable for drinking and their quality for irrigation fluctuates from excellent to moderate quality. Full article
(This article belongs to the Special Issue Advanced Research in Groundwater Geochemistry)
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39 pages, 3658 KiB  
Review
An Overview of the Numerical Approaches to Water Hammer Modelling: The Ongoing Quest for Practical and Accurate Numerical Approaches
by Susovan Pal, Prashanth Reddy Hanmaiahgari and Bryan W. Karney
Water 2021, 13(11), 1597; https://doi.org/10.3390/w13111597 - 5 Jun 2021
Cited by 32 | Viewed by 8527
Abstract
Here, recent developments in the key numerical approaches to water hammer modelling are summarized and critiqued. This paper summarizes one-dimensional modelling using the finite difference method (FDM), the method of characteristics (MOC), and especially the more recent finite volume method (FVM). The discussion [...] Read more.
Here, recent developments in the key numerical approaches to water hammer modelling are summarized and critiqued. This paper summarizes one-dimensional modelling using the finite difference method (FDM), the method of characteristics (MOC), and especially the more recent finite volume method (FVM). The discussion is briefly extended to two-dimensional modelling, as well as to computational fluid dynamics (CFD) approaches. Finite volume methods are of particular note, since they approximate the governing partial differential equations (PDEs) in a volume integral form, thus intrinsically conserving mass and momentum fluxes. Accuracy in transient modelling is particularly important in certain (typically more nuanced) applications, including fault (leakage and blockage) detection. The FVM, first advanced using Godunov’s scheme, is preferred in cases where wave celerity evolves over time (e.g., due to the release of air) or due to spatial changes (e.g., due to changes in wall thickness). Both numerical and experimental studies demonstrate that the first-order Godunov’s scheme compares favourably with the MOC in terms of accuracy and computational speed; with further advances in the FVM schemes, it progressively achieves faster and more accurate codes. The current range of numerical methods is discussed and illustrated, including highlighting both their limitations and their advantages. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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14 pages, 4814 KiB  
Article
The Effect of Wall Shear Stress on Two Phase Fluctuating Flow of Dusty Fluids by Using Light Hill Technique
by Dolat Khan, Ata ur Rahman, Gohar Ali, Poom Kumam, Attapol Kaewkhao and Ilyas Khan
Water 2021, 13(11), 1587; https://doi.org/10.3390/w13111587 - 4 Jun 2021
Cited by 21 | Viewed by 4281
Abstract
Due to the importance of wall shear stress effect and dust fluid in daily life fluid problems. This paper aims to discover the influence of wall shear stress on dust fluids of fluctuating flow. The flow is considered between two parallel plates that [...] Read more.
Due to the importance of wall shear stress effect and dust fluid in daily life fluid problems. This paper aims to discover the influence of wall shear stress on dust fluids of fluctuating flow. The flow is considered between two parallel plates that are non-conducting. Due to the transformation of heat, the fluid flow is generated. We consider every dust particle having spherical uniformly disperse in the base fluid. The perturb solution is obtained by applying the Poincare-Lighthill perturbation technique (PLPT). The fluid velocity and shear stress are discussed for the different parameters like Grashof number, magnetic parameter, radiation parameter, and dusty fluid parameter. Graphical results for fluid and dust particles are plotted through Mathcad-15. The behavior of base fluid and dusty fluid is matching for different embedded parameters. Full article
(This article belongs to the Special Issue Gas-Liquid Two-Phase Flow in the Pipe or Channel)
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17 pages, 750 KiB  
Review
Sustainable, Decentralized Sanitation and Reuse with Hybrid Nature-Based Systems
by Andrea G. Capodaglio, Silvia Bolognesi and Daniele Cecconet
Water 2021, 13(11), 1583; https://doi.org/10.3390/w13111583 - 3 Jun 2021
Cited by 38 | Viewed by 5504
Abstract
Nature (ecosystem) based processes for wastewater treatment include constructed wetlands (CWs), waste stabilization ponds, vegetated drainage ditches, buffer zones, instream or bankside river techniques, and mixotrophic systems, where light and CO2 are utilized, in addition to organic carbon compounds, by algal cultures. [...] Read more.
Nature (ecosystem) based processes for wastewater treatment include constructed wetlands (CWs), waste stabilization ponds, vegetated drainage ditches, buffer zones, instream or bankside river techniques, and mixotrophic systems, where light and CO2 are utilized, in addition to organic carbon compounds, by algal cultures. Algae-based systems can simultaneously remove organic matter, N, and P and may offer substantial energetic advantages compared to traditional biological treatment systems, require small spatial footprint, and contribute to biofuels production and CO2 emissions mitigation. Bioelectrochemical systems (BES) such as microbial fuel cells (MFCs) present characteristics compatible with the use in isolated realities for water and wastewater treatment with contextual energy recovery and may be combined with other nature-based process technologies to achieve good treatment and energy efficiencies. Despite that their application in real-scale plants has not been assessed yet, the most probable outcome will be the in situ/on site treatment (or pretreatment) of wastes for small “in house” plants not connected to the sewerage network. This paper focuses on the current practices and perspectives of hybrid nature-based systems, such as constructed wetlands and microalgae integrated phytoremediation plants, and their possible integration with microbial electrochemical technologies to increase recovery possibilities from wastes and positively contribute to a green economy approach. Full article
(This article belongs to the Special Issue Hybrid Systems Using Different Technologies for Wastewater Treatment and Reuse)
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23 pages, 8240 KiB  
Article
Improving Urban Flood Mapping by Merging Synthetic Aperture Radar-Derived Flood Footprints with Flood Hazard Maps
by David C. Mason, John Bevington, Sarah L. Dance, Beatriz Revilla-Romero, Richard Smith, Sanita Vetra-Carvalho and Hannah L. Cloke
Water 2021, 13(11), 1577; https://doi.org/10.3390/w13111577 - 2 Jun 2021
Cited by 22 | Viewed by 6763
Abstract
Remotely sensed flood extents obtained in near real-time can be used for emergency flood incident management and as observations for assimilation into flood forecasting models. High-resolution synthetic aperture radar (SAR) sensors have the potential to detect flood extents in urban areas through clouds [...] Read more.
Remotely sensed flood extents obtained in near real-time can be used for emergency flood incident management and as observations for assimilation into flood forecasting models. High-resolution synthetic aperture radar (SAR) sensors have the potential to detect flood extents in urban areas through clouds during both day- and night-time. This paper considers a method for detecting flooding in urban areas by merging near real-time SAR flood extents with model-derived flood hazard maps. This allows a two-way symbiosis, whereby currently available SAR urban flood extent improves future model flood predictions, while flood hazard maps obtained after the SAR overpasses improve the SAR estimate of urban flood extents. The method estimates urban flooding using SAR backscatter only in rural areas adjacent to urban ones. It was compared to an existing method using SAR returns in both rural and urban areas. The method using SAR solely in rural areas gave an average flood detection accuracy of 94% and a false positive rate of 9% in the urban areas and was more accurate than the existing method. Full article
(This article belongs to the Special Issue Improving Flood Detection and Monitoring through Remote Sensing)
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20 pages, 4719 KiB  
Article
Observations of Tidal Flat Sedimentation within a Native and an Exotic Spartina Species
by Barbara Proença, Florian Ganthy, Richard Michalet and Aldo Sottolichio
Water 2021, 13(11), 1566; https://doi.org/10.3390/w13111566 - 1 Jun 2021
Cited by 2 | Viewed by 3744
Abstract
Field measurements of bed elevation and related wave events were performed within a tidal marsh, on two cordgrass species, Spartina anglica (exotic) and Spartina maritima (native), in the Bay of Arcachon (SW France). Bed- and water-level time series were used to infer on [...] Read more.
Field measurements of bed elevation and related wave events were performed within a tidal marsh, on two cordgrass species, Spartina anglica (exotic) and Spartina maritima (native), in the Bay of Arcachon (SW France). Bed- and water-level time series were used to infer on the sediment behavior patterns from short to long term. A consistent response was found between the bed-level variation and the wave forcing, with erosion occurring during storms and accretion during low energy periods. Such behavior was observed within the two species, but the magnitude of bed-level variation was higher within the native than the exotic Spartina. These differences, in the order of millimeters, were explained by the opposite allocation of biomass of the two species. On the long term, the sedimentation/erosion patterns were dominated by episodic storm events. A general sediment deficit was observed on the site, suggested by an overall bed-level decrease registered within both species. However, further verification of within species variation needs to be considered when drawing conclusions. Despite possible qualitative limitations of the experimental design, due to single point survey, this work provides original and considerable field data to the understanding the different species ability to influence bed sediment stabilization and their potential to build marsh from the mudflat pioneer stage. Such information is valuable for coastal management in the context of global change. Full article
(This article belongs to the Special Issue Hydro-Sedimentary Processes and Methods in Estuarine and Coastal Environments)
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12 pages, 2665 KiB  
Article
Interactive Visualisation of Sustainability Indicators for Water, Energy and Food Innovations
by Paula J. Forbes, Ruth E. Falconer, Daniel Gilmour and Nikolay Panayotov
Water 2021, 13(11), 1571; https://doi.org/10.3390/w13111571 - 1 Jun 2021
Cited by 1 | Viewed by 3532
Abstract
The Water-Energy-Food (WEF) nexus describes the synergies and trade-offs between water, energy and food. Despite the significant attention that the WEF nexus has received in recent years, challenges remain, primarily related to gaps in integrated data, information and knowledge related to the most [...] Read more.
The Water-Energy-Food (WEF) nexus describes the synergies and trade-offs between water, energy and food. Despite the significant attention that the WEF nexus has received in recent years, challenges remain, primarily related to gaps in integrated data, information and knowledge related to the most critical inter-linkages and their dynamics. These WEF nexus complexities and uncertainty make decision-making and future forecasting extremely difficult. Policy makers and other stakeholders are currently faced with the task of understanding longer term environmental impacts and tJhe benefits and limitations of innovations that could be potentially beneficial, such as Anaerobic Digestion as a waste solution or insect protein production. This paper describes an approach to support decision making for local-level innovations within the WEF nexus by creating a set of sustainability indicators and an accompanying interactive visualisation. The indicators were derived from stakeholder consultation processes and workshops, and they were selected to include a much broader assessment than just financial aspects when considering the viability of such innovations. By taking this bottom-up approach and placing stakeholders at the heart of the project, we produced a visualisation tool to support sustainable decision making when considering the implementation of WEF innovations. Considering other, often overlooked factors and giving greater priority to these deepens knowledge and the recognition of influential issues that in conventional processes may be overlooked. This visualisation tool is designed to support decision makers to engage in a exploration of the different interlinkages, and to be the basis of stakeholder dialogue around sustainability. The visualisation tool developed was designed to be easily modifiable in order to be updated with new insights and to include other future innovations. Full article
(This article belongs to the Special Issue The Water-Energy-Food Nexus: Sustainable Development)
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21 pages, 5461 KiB  
Article
Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation
by Vando J. C. Gomes, Nils E. Asp, Eduardo Siegle, José Diego Gomes, Ariane M. M. Silva, Andrea S. Ogston and Charles A. Nittrouer
Water 2021, 13(11), 1568; https://doi.org/10.3390/w13111568 - 1 Jun 2021
Cited by 14 | Viewed by 4285
Abstract
In tide-dominated estuaries, maximum-turbidity zones (MTZs) are common and prominent features, characterized by a peak in suspended-sediment concentration (SSC) associated with estuarine processes. The Brazilian Amazon coast includes many estuaries, experiencing macrotidal conditions. MTZs are expected to occur and are crucial for sediment [...] Read more.
In tide-dominated estuaries, maximum-turbidity zones (MTZs) are common and prominent features, characterized by a peak in suspended-sediment concentration (SSC) associated with estuarine processes. The Brazilian Amazon coast includes many estuaries, experiencing macrotidal conditions. MTZs are expected to occur and are crucial for sediment delivery to the longest continuous mangrove belt of the world. The area is under influence of the Amazon River plume (ARP), the main SSC source, as local rivers do not deliver substantial sediment supply. To assess the processes that allow the ARP to supply sediment to the estuaries and mangrove belt along the Amazon coast, the results from previous individual studies within five Amazon estuaries (Mocajuba, Taperaçu, Caeté, Urumajó and Gurupi) were compared with regards to SSC, salinity, morphology and tidal propagation. This comparison reinforces that these estuaries are subject to similar regional climate and tidal variations, but that their dynamics differ in terms of distance from the Amazon River mouth, importance of the local river sediment source, and morphology of the estuarine setting. The Urumajó, Caeté and Gurupi are hypersynchronous estuaries where perennial, classic MTZs are observed with SSC > 1 g·L−1. This type of estuary results in transport convergence and MTZ formation, which are suggested to be the main processes promoting mud accumulation in the Amazonian estuaries and therefore the main means of mud entrapment in the mangrove belt. The Mocajuba and the Taperaçu estuaries showed synchronous and hyposynchronous processes, respectively, and do not present classic MTZs. In these cases, the proximity to the ARP for the Mocajuba and highly connected tidal channels for the Taperaçu estuary, assure substantial mud supply into these estuaries. This study shows the strong dependence of the estuaries and mangrove belt on sediment supply from the ARP, helping to understand the fate of Amazon River sediments and providing insights into the mechanisms providing sediment to estuaries and mangroves around the world, especially under the influence of big rivers. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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13 pages, 8177 KiB  
Article
Palladium-Supported Zirconia-Based Catalytic Degradation of Rhodamine-B Dye from Wastewater
by Salma Jabeen, Muhammad Sufaid Khan, Rozina Khattak, Ivar Zekker, Juris Burlakovs, Sergio S. dC Rubin, Makarand Madhao Ghangrekar, Anna Kallistova, Nikolai Pimenov, Muhammad Zahoor and Gul Shahzada Khan
Water 2021, 13(11), 1522; https://doi.org/10.3390/w13111522 - 28 May 2021
Cited by 52 | Viewed by 4081
Abstract
The catalytic activity of Pd/ZrO2 was studied in terms of the degradation of rhodamine-B dye in the presence of hydrogen peroxide. Pd/ZrO2 was prepared by impregnation method, calcined at 750 °C and characterized by XRD, SEM and EDX. The catalyst showed [...] Read more.
The catalytic activity of Pd/ZrO2 was studied in terms of the degradation of rhodamine-B dye in the presence of hydrogen peroxide. Pd/ZrO2 was prepared by impregnation method, calcined at 750 °C and characterized by XRD, SEM and EDX. The catalyst showed good catalytic activity for dye degradation at 333 K, using 0.05 g of the catalyst during 5 h. The reaction kinetics followed the pseudo-first order kinetics. The Freundlich, Langmuir and Temkin isotherms were applied to the data and the best fit was obtained with Freundlich isotherm. Thermodynamic parameters, like ΔH, ΔG and ΔS were also calculated. The negative values of ΔH (−291.406 KJ/mol) and Gibbs free energy (ΔG) showed the exothermic and spontaneous nature of the process. The positive ΔS (0.04832 KJ/mol K) value showed suitable affinity of catalyst for dye degradation. The catalyst was very stable, active and was easily separated from the reaction mixture by filtration. It can be concluded from the results that the prepared catalyst could be effectively used in dyes degradation/removal from water subjected to further validation and use for various dyes. Full article
(This article belongs to the Special Issue Recent Advances in Bioreactors and Heavy Metals Removal/Recovery during Waste Post-treatment)
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13 pages, 5122 KiB  
Article
Research on the Measurement and Influencing Factors of Implicit Water Resources in Import and Export Trade from the Perspective of Global Value Chains
by Min Huang, Chengying Xu, Fengting Wang, Lichun Xiong and Kai Zhou
Water 2021, 13(11), 1498; https://doi.org/10.3390/w13111498 - 27 May 2021
Cited by 3 | Viewed by 3395
Abstract
In this study, China’s virtual water trade was measured on the basis of multi-region input/output tables, and its influencing factors of change were decomposed. The results revealed that virtual water export and import increased from 161.5 billion tons and 114.07 billion tons in [...] Read more.
In this study, China’s virtual water trade was measured on the basis of multi-region input/output tables, and its influencing factors of change were decomposed. The results revealed that virtual water export and import increased from 161.5 billion tons and 114.07 billion tons in 2007 to 193.31 billion tons and 157.1 billion tons in 2014, respectively. Eight economies accounted for more than 50% of China’s total virtual water export and import, whereby the total of the United States, Japan, and Europe reached 44% (export) and 31.3% (import). The export scale, export of intermediate products, export industry structure, domestic water consumption coefficient, and domestic intermediate input structure were the main factors of the change in virtual water export. The growth of export scale was the primary reason for the growth of virtual water export. A decline in the domestic water consumption coefficient was the primary reason for the restrained growth of virtual water export. The import scale, import of intermediate products, import industry structure, water consumption coefficient of foreign countries, and the correlation among domestic industries were the main factors affecting the change in virtual water import. The growth of import scale was the primary reason for the growth of virtual water import in most sectors. A decline in the water consumption coefficient abroad was the primary reason for the restrained growth of virtual water import. Full article
(This article belongs to the Special Issue Research on the Economic Value of Virtual Water)
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18 pages, 3264 KiB  
Article
Hydroxyapatite Coatings on Calcite Powder for the Removal of Heavy Metals from Contaminated Water
by Oriol Gibert, César Valderrama, María M. Martínez, Rosa Mari Darbra, Josep Oliva Moncunill and Vicenç Martí
Water 2021, 13(11), 1493; https://doi.org/10.3390/w13111493 - 27 May 2021
Cited by 19 | Viewed by 3923
Abstract
An approach for the remediation of heavy metal-contaminated wastewater that is gaining increasing attention is the application of hydroxyapatite (HAP)-based particles. HAP is conventionally synthesized through wet chemical precipitation of calcium and phosphate ions, although later studies have focused on HAP synthesis from [...] Read more.
An approach for the remediation of heavy metal-contaminated wastewater that is gaining increasing attention is the application of hydroxyapatite (HAP)-based particles. HAP is conventionally synthesized through wet chemical precipitation of calcium and phosphate ions, although later studies have focused on HAP synthesis from solid calcite contacted with a phosphate solution under ambient conditions. This synthesis route can allow saving soluble Ca-chemicals and, thus, make the process more cost-efficient. The aim of this study was to coat natural calcite powder with a layer of HAP for the removal of Zn and Cu from contaminated water. For this purpose, a HAP layer was synthesized on calcite particles, characterized using several complementary techniques and evaluated for the removal of Zn and Cu from synthetic solutions. Sorption kinetics and equilibrium isotherms, as well as the effect of sonication of the synthesized sample on its sorption performance, were determined. The results showed that calcite particles were efficiently coated with a HAP layer with high capacity in removing Zn and Cu from acidic solutions, with a qmax of 34.97 mg/g for Zn (increased to 37.88 g/mg after sonication of the sample) and 60.24 mg/g for Cu (which hardly varied with sonication). The mechanisms behind the sorption of Zn and Cu onto HAP, inferred from pH changes, the relation between metal uptake and Ca2+ release and XRD analysis, included surface complexation, ion exchange and precipitation of new Zn- and Cu-containing phases. Full article
(This article belongs to the Special Issue Wastewater Treatment by Adsorption and/or Ion-Exchange Processes for Resource Recovery)
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21 pages, 1186 KiB  
Article
Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events
by Rachel M. Chalmers, Lester P. Simmonds, Martin Wood, Megan Luxford, Rob Miller and Rob Johnston
Water 2021, 13(11), 1503; https://doi.org/10.3390/w13111503 - 27 May 2021
Cited by 4 | Viewed by 3769
Abstract
Cryptosporidium is a major cause of diarrhoea outbreaks linked to swimming pools, but little is known about the frequency of contamination. The primary aim was to investigate the occurrence and concentration, through sampling and modelling, of Cryptosporidium oocysts in leisure pools. Secondary aims [...] Read more.
Cryptosporidium is a major cause of diarrhoea outbreaks linked to swimming pools, but little is known about the frequency of contamination. The primary aim was to investigate the occurrence and concentration, through sampling and modelling, of Cryptosporidium oocysts in leisure pools. Secondary aims were to compare detections with operational parameters, provide the evidence-base for guidance, and improve sampling capacity and interpretation for public health investigations. Up to 1000 L pool water was sampled during swim sessions once weekly for 10 weeks from 8 August 2017 at six volunteer pools. Oocysts were detected by microscopy in 12/59 (20%) pool water samples, at least once in each pool; 8/12 (66%) detections were in August when bather loads were highest. At three pools, 1 L filter backwash was sampled weekly and oocysts were detected in 2/29 (7%) samples, following detections in pool water. The probabilities of a bather contaminating the pool ranged from 1 in 1000 to over 1 in 10,000. Monte Carlo analysis showed that when high bather numbers caused contamination on over 70% of days, multiple events per day were more likely than single events. In these generally well-managed leisure pools, Cryptosporidium risk related to high bather loads. We conclude that public awareness campaigns for bather hygiene, and reminding pool operators of current guidance for managing faecal accidents, should be ahead of peak swim season. Full article
(This article belongs to the Special Issue Healthy Recreational Waters: Sanitation and Safety Issues)
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21 pages, 7251 KiB  
Article
The Role of Faults in Groundwater Circulation before and after Seismic Events: Insights from Tracers, Water Isotopes and Geochemistry
by Davide Fronzi, Francesco Mirabella, Carlo Cardellini, Stefano Caliro, Stefano Palpacelli, Costanza Cambi, Daniela Valigi and Alberto Tazioli
Water 2021, 13(11), 1499; https://doi.org/10.3390/w13111499 - 27 May 2021
Cited by 32 | Viewed by 6611
Abstract
The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, [...] Read more.
The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, the lower crustal portion and the upraising of gasses carried by liquids. Many other scientific works try to explore the interaction between the recharge processes, i.e., precipitation, and the fault zones, aiming to recognize the function of the abovementioned structures and their capability to direct groundwater flow towards preferential drainage areas. Understanding the role of faults in the recharge processes of punctual and linear springs, meant as gaining streams, is a key point in hydrogeology, as it is known that faults can act either as flow barriers or as preferential flow paths. In this work an investigation of a fault system located in the Nera River catchment (Italy), based on geo-structural investigations, tracer tests, geochemical and isotopic recharge modelling, allows to identify the role of the normal fault system before and after the 2016–2017 central Italy seismic sequence (Mmax = 6.5). The outcome was achieved by an integrated approach consisting of a structural geology field work, combined with GIS-based analysis, and of a hydrogeological investigation based on artificial tracer tests and geochemical and isotopic analyses. Full article
(This article belongs to the Special Issue Applying Artificial and Environmental Tracing Techniques in Hydrogeology)
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14 pages, 577 KiB  
Article
Removal of Fluorides from Aqueous Solutions Using Exhausted Coffee Grounds and Iron Sludge
by Irma Siaurusevičiūtė and Ramunė Albrektienė
Water 2021, 13(11), 1512; https://doi.org/10.3390/w13111512 - 27 May 2021
Cited by 10 | Viewed by 4689
Abstract
Many countries are confronted with a striking problem of morbidity of fluorosis that appears because of an increased concentration of fluorides in drinking water. The objective of this study is to explore opportunities for removal of fluoride from aqueous solutions using cheap and [...] Read more.
Many countries are confronted with a striking problem of morbidity of fluorosis that appears because of an increased concentration of fluorides in drinking water. The objective of this study is to explore opportunities for removal of fluoride from aqueous solutions using cheap and easily accessible adsorbents, such as exhaustive coffee grounds and iron sludge and to establish the efficiency of fluoride removal. Twelve doses (1, 2, 3, 4, 5, 6, 10, 20, 30, 40, 50 and 60 g/L) of adsorbents were used and five durations of the sorption process (30, 60, 90, 120 and 150 min). The results showed that the most optimum dose of iron sludge for 3 mg/L of fluoride removal was 30 g/L and the contact time was 30 min, the efficiency of fluoride removal achieved 62.92%; the most optimum dose of exhausted coffee grounds was 60 g/L with the most optimum contact time of 60 min; at a dose of 50 g/L with contact time of 90 min, the efficiency of fluoride removal achieved 56.67%. Findings demonstrate that adsorbents have potential applicability in fluoride removal up to the permissible norms. Full article
(This article belongs to the Section Water and One Health)
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9 pages, 2650 KiB  
Article
Analysis of the Spatiotemporal Annual Rainfall Variability in the Wadi Cheliff Basin (Algeria) over the Period 1970 to 2018
by Mohammed Achite, Tommaso Caloiero, Andrzej Wałęga, Nir Krakauer and Tarek Hartani
Water 2021, 13(11), 1477; https://doi.org/10.3390/w13111477 - 25 May 2021
Cited by 19 | Viewed by 4621
Abstract
In the context of climate variability and hydrological extremes, especially in arid and semi-arid zones, the issue of natural risks and more particularly the risks related to rainfall is a topical subject in Algeria and worldwide. In this direction, the spatiotemporal variability of [...] Read more.
In the context of climate variability and hydrological extremes, especially in arid and semi-arid zones, the issue of natural risks and more particularly the risks related to rainfall is a topical subject in Algeria and worldwide. In this direction, the spatiotemporal variability of precipitation in the Wadi Cheliff basin (Algeria) has been evaluated by means of annual time series of precipitation observed on 150 rain gauges in the period 1970–2018. First, in order to identify the natural year-to-year variability of precipitation, for each series, the coefficient of variation (CV) has been evaluated and spatially distributed. Then, the precipitation trend at annual scale has been analyzed using two nonparametric tests. Finally, the presence of possible change points in the data has been investigated. The results showed an inverse spatial pattern between CV and the annual rainfall, with a spatial gradient between the southern and the northern sides of the basin. Results of the trend analysis evidenced a marked negative trend of the annual rainfall (22% of the rain gauges for a significant level equal to 95%) involving mainly the northern and the western-central area of the basin. Finally, possible change points have been identified between 1980 and 1985. Full article
(This article belongs to the Special Issue Hydrology in Water Resources Management)
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20 pages, 3466 KiB  
Article
Hydrological Extremes and Responses to Climate Change in the Kelantan River Basin, Malaysia, Based on the CMIP6 HighResMIP Experiments
by Mou Leong Tan, Ju Liang, Narimah Samat, Ngai Weng Chan, James M. Haywood and Kevin Hodges
Water 2021, 13(11), 1472; https://doi.org/10.3390/w13111472 - 24 May 2021
Cited by 37 | Viewed by 8052
Abstract
This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six [...] Read more.
This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were computed to assess future extreme flows in the Kelantan River Basin (KRB), Malaysia, which is particularly vulnerable to flooding. Results show that the annual precipitation, streamflow, maximum and minimum temperatures are projected to increase by 6.9%, 9.9%, 0.8 °C and 0.9 °C, respectively, by the 2021–2050 period relative to the 1985–2014 baseline. Monthly precipitation and streamflow are projected to increase especially for the Southwest Monsoon (June–September) and the early phase of the Northeast Monsoon (December) periods. The magnitudes of the 1-, 3-, 7-, 30- and 90-day minima flows are projected to increase by 7.2% to 8.2% and the maxima flows by 10.4% to 28.4%, respectively. Lastly, changes in future hydro-climatic extremes are frequently quite different between the high-resolution and low-resolution models, e.g., the high-resolution models projected an increase of 11.8% in mean monthly flow in November-December-January compared to 3.2% for the low-resolution models. Full article
(This article belongs to the Special Issue Hydrological Extremes in a Warming Climate: Nonstationarity, Uncertainties and Impacts)
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16 pages, 34920 KiB  
Article
Detecting Groundwater Temperature Shifts of a Subsurface Urban Heat Island in SE Germany
by Julian A. V. Schweighofer, Michael Wehrl, Sebastian Baumgärtel and Joachim Rohn
Water 2021, 13(10), 1417; https://doi.org/10.3390/w13101417 - 19 May 2021
Cited by 10 | Viewed by 4183
Abstract
The subsurface beneath cities commonly shows a temperature anomaly, a so-called Subsurface Urban Heat Island (SUHI), due to anthropogenic heat input. This excess heat has multiple effects on groundwater and energy resources, such as groundwater chemistry or the efficiency of geothermal systems, which [...] Read more.
The subsurface beneath cities commonly shows a temperature anomaly, a so-called Subsurface Urban Heat Island (SUHI), due to anthropogenic heat input. This excess heat has multiple effects on groundwater and energy resources, such as groundwater chemistry or the efficiency of geothermal systems, which makes it necessary to investigate the temporal development of a SUHI. For this purpose, temperature profiles of 38 observation wells in the German city of Nuremberg were evaluated from 2015 to 2020 and the measured temperature changes were linked to the surface sealing. The results show that the groundwater temperatures changed between −0.02 K/a and +0.21 K/a, on average by +0.07 K/a during this period. A dependence between the temperature increase and the degree of sealing of the land surface was also observed. In areas with low surface sealing of up to 30% the warming amounts were 0.03 K/a on average, whereas in areas with high sealing of over 60% significantly higher temperature increases of 0.08 K/a on average were found. The results clearly emphasize that the subsurface urban heat island in its current state does not represent a completed process, but that more heat energy continues to enter the subsoil within the city than is the case with near-natural land surfaces. Full article
(This article belongs to the Section Hydrology)
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15 pages, 2720 KiB  
Article
A Geographical Information Approach for Forest Maintenance Operations with Emphasis on the Drainage Infrastructure and Culverts
by Apostolos Kantartzis, Chrisovalantis Malesios, Anastasia Stergiadou, Nikolas Theofanous, Stergios Tampekis and Garyfallos Arabatzis
Water 2021, 13(10), 1408; https://doi.org/10.3390/w13101408 - 18 May 2021
Cited by 10 | Viewed by 3453
Abstract
Forest operations engineering deals with all the essential infrastructure operations aiming at the efficient management of forested areas, which constitutes a prerequisite for the development of mountainous economies. Thus, the need for addressing this objective in an effective way, in conjunction with other [...] Read more.
Forest operations engineering deals with all the essential infrastructure operations aiming at the efficient management of forested areas, which constitutes a prerequisite for the development of mountainous economies. Thus, the need for addressing this objective in an effective way, in conjunction with other issues associated with the protection and preservation of forest wealth, is of utmost importance. There are a whole range of forest operations for which a decision-making web-tool can potentially be utilized. This paper introduces an online decision-making tool for managing forest roads, which uses information derived from rainfall-runoff simulation. The proposed tool can be used to provide information about forest works maintenance and damage prevention in a forest environment. Furthermore, the tool assists in visualizing forest operations and achieves the optimization of their management. The development of the decision-making tool is also described, and a real case study (the Koupa watershed) is presented in detail to demonstrate its application and resulting advantages. The rainfall-runoff simulation was conducted for ten sub-basins in order to evaluate the efficiency of the corresponding culverts in the Koupa watershed. Full article
(This article belongs to the Special Issue Natural Ecosystems Management and Mountain Engineering Works as Tools for Runoff and Sediment Yield Control)
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20 pages, 7729 KiB  
Article
Identification of Extreme Weather Events Using Meteorological and Hydrological Indicators in the Laborec River Catchment, Slovakia
by Katarzyna Kubiak-Wójcicka, Patrik Nagy, Martina Zeleňáková, Helena Hlavatá and Hany F. Abd-Elhamid
Water 2021, 13(10), 1413; https://doi.org/10.3390/w13101413 - 18 May 2021
Cited by 17 | Viewed by 3613
Abstract
This study used the standardized precipitation index (SPI) and the standardized runoff index (SRI) to analyze dry and humid conditions in the hill-country catchment area of the Laborec River (Slovakia) over a period of 50 years (1970–2019). Analysis of the SPI and SRI [...] Read more.
This study used the standardized precipitation index (SPI) and the standardized runoff index (SRI) to analyze dry and humid conditions in the hill-country catchment area of the Laborec River (Slovakia) over a period of 50 years (1970–2019). Analysis of the SPI and SRI over various time scales showed the occurrence of wet periods (index > 1.0) that were associated with precipitation exceeding the long-term norm, and dry periods (index below −1.0), which were the result of small amounts of precipitation. Analysis of the correlation between the SPI and SRI on different time scales revealed that the catchment showed a weaker response to precipitation over short time scales (1 and 3 months) and a stronger response over longer accumulation periods (6, 9, and 12 months). The highest annual correlation coefficient (r = 0.72) was recorded between SRI-6 at the Humenne hydrometric station and SPI-9 at the Medzilaborce meteorological station in the upper part of the catchment area. The strongest annual correlation (r = 0.69) was obtained between the Izkovce and Kamenica stations in the lower part of the catchment area. As shown by the cross-relationships examined over different periods of accumulation of flows and precipitation, hydrological droughts appeared as a result of the occurrence of meteorological droughts with a three-month delay. The conducted analysis showed that in the case of the Laborec river catchment area, there was a strong correlation between the occurrence of meteorological drought and hydrological drought. Full article
(This article belongs to the Special Issue Assessment and Management of Flood Risk in Urban Areas)
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19 pages, 1241 KiB  
Article
The Influence of Hydropower and Coal Consumption on Greenhouse Gas Emissions: A Comparison between China and India
by Ugur Korkut Pata and Amit Kumar
Water 2021, 13(10), 1387; https://doi.org/10.3390/w13101387 - 16 May 2021
Cited by 92 | Viewed by 6387
Abstract
This study mainly aims to investigate carbon status according to the Pollution Haven Hypothesis (PHH) in developing countries such as India and China based on annual time series data from 1980 to 2016. The recently developed bootstrap autoregressive distributed lag procedure is applied [...] Read more.
This study mainly aims to investigate carbon status according to the Pollution Haven Hypothesis (PHH) in developing countries such as India and China based on annual time series data from 1980 to 2016. The recently developed bootstrap autoregressive distributed lag procedure is applied to observe the long-run effect of FDI, hydropower, and coal-based fossil fuel consumption on three repressive measures of carbon emissions. The empirical results of the analysis show that hydropower and coal consumption lead to an upsurge in carbon emissions and the size of the carbon footprint in China. Similarly, Chinese FDI increases the carbon footprint. Moreover, Indian FDI and coal consumption accelerate carbon emissions while hydropower has no impact on environmental degradation. These results suggest that the PHH exists in China and India and that the validity of the PHH varies according to differing carbon indicators. Based on the empirical results, effective policy practices can be implemented by replacing coal and hydropower with more effective renewable energy sources and allowing foreign investors to pursue environmental concerns in the fight against environmental degradation. Full article
(This article belongs to the Special Issue Greenhouse Gas Emission from Freshwater Ecosystem)
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31 pages, 3703 KiB  
Article
Sediment Balance Estimation of the ‘Cuvette Centrale’ of the Congo River Basin Using the SWAT Hydrological Model
by Pankyes Datok, Sabine Sauvage, Clément Fabre, Alain Laraque, Sylvain Ouillon, Guy Moukandi N’kaya and José-Miguel Sanchez-Perez
Water 2021, 13(10), 1388; https://doi.org/10.3390/w13101388 - 16 May 2021
Cited by 7 | Viewed by 4943
Abstract
In this study, the SWAT hydrological model was used to estimate the sediment yields in the principal drainage basins of the Congo River Basin. The model was run for the 2000–2012 period and calibrated using measured values obtained at the basins principal gauging [...] Read more.
In this study, the SWAT hydrological model was used to estimate the sediment yields in the principal drainage basins of the Congo River Basin. The model was run for the 2000–2012 period and calibrated using measured values obtained at the basins principal gauging station that controls 98% of the basin area. Sediment yield rates of 4.01, 5.91, 7.88 and 8.68 t km−2 yr−1 were estimated for the areas upstream of the Ubangi at Bangui, Sangha at Ouesso, Lualaba at Kisangani, and Kasai at Kuto-Moke, respectively—the first three of which supply the Cuvette Centrale. The loads contributed into the Cuvette Centrale by eight tributaries were estimated to be worth 0.04, 0.07, 0.09, 0.18, 0.94, 1.50, 1.60, and 26.98 × 106 t yr−1 from the Likouala Mossaka at Makoua, Likouala aux Herbes at Botouali, Kouyou at Linnegue, Alima at Tchikapika, Sangha at Ouesso, Ubangi at Mongoumba, Ruki at Bokuma and Congo at Mbandaka, respectively. The upper Congo supplies up to 85% of the fluxes in the Cuvette Centrale, with the Ubangi and the Ruki contributing approximately 5% each. The Cuvette Centrale acts like a big sink trapping up to 23 megatons of sediment produced upstream (75%) annually. Full article
(This article belongs to the Special Issue Modelling of River Flows, Sediment and Contaminants Transport)
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20 pages, 3625 KiB  
Article
Adsorption of Azo-Anionic Dyes in a Solution Using Modified Coconut (Cocos nucifera) Mesocarp: Kinetic and Equilibrium Study
by Candelaria Tejada-Tovar, Ángel Villabona-Ortíz and Ángel Darío Gonzalez-Delgado
Water 2021, 13(10), 1382; https://doi.org/10.3390/w13101382 - 15 May 2021
Cited by 44 | Viewed by 4192
Abstract
The effect of adsorbent dose and initial concentration on removing the azo-anionic dyes Congo Red andtartrazine present in a synthetic aqueous solution was studied using natural cellulose (CC) and modified cationic cellulose (MCC) from coconut mesocarp. Three levels of adsorbent dosage (5, 8 [...] Read more.
The effect of adsorbent dose and initial concentration on removing the azo-anionic dyes Congo Red andtartrazine present in a synthetic aqueous solution was studied using natural cellulose (CC) and modified cationic cellulose (MCC) from coconut mesocarp. Three levels of adsorbent dosage (5, 8 and 12 mg/L) and initial concentration (40, 70 and 100 mg/L) were used. Cetyl trimethyl ammonium chloride (CTAC) was used as a modifying agent. TGA and DSC showed that the extracted cellulose was of good quality, composed mostly of cellulose with lignin and hemicellulose traces, and 8% moisture. The FTIR spectrum showed the effectiveness of the modification in the structure of the material with symmetric deformation of the C6H6-Cl group in 1472 cm−1 present in the CTAC. It was found that decreasing the adsorbent dosage and increasing the initial concentration favored the dyes’ adsorption capacity on the two bioadsorbents. Tartrazine removals of 5.67 mg/g on CC and 19.61 mg/g on MCC were achieved, and for CR of 15.52 mg/g on CC and 19.99 with MCC with removal percentages over 97% with the quaternized biomass in all cases. The kinetic and equilibrium study was carried out to identify the mechanisms involved in the adsorption process. The Freundlich model can describe the equilibrium isotherm data of tartrazine on CC and MCC. In contrast, those of CR is defined by the Langmuir and Dubinin–Radushkevic models for CC and MCC, respectively Adsorption kinetics showed that equilibrium was reached at 30 min, with rapid adsorption in the initial minutes with the removal of about 97% of the contaminant in the first 5 min; fitting to kinetic models showed that the kinetics of tartrazine on CC was fitted by Elovich (R2 = 0.756), and on MCC the Elovich (R2 = 0.887) and pseudo-second-order (R2 = 0.999) models. Removing CR on CC was fitted by pseudo-first-order, pseudo-second-order and Elovich models (R2 > 0.98), and when using MCC, all models show a good fitting with R2 = 0.99 in all cases. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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40 pages, 5304 KiB  
Review
Recent Desalination Technologies by Hybridization and Integration with Reverse Osmosis: A Review
by Jhon Jairo Feria-Díaz, Felipe Correa-Mahecha, María Cristina López-Méndez, Juan Pablo Rodríguez-Miranda and Jesús Barrera-Rojas
Water 2021, 13(10), 1369; https://doi.org/10.3390/w13101369 - 14 May 2021
Cited by 105 | Viewed by 20020
Abstract
Reverse osmosis is the leading technology for desalination of brackish water and seawater, important for solving the growing problems of fresh water supply. Thermal technologies such as multi-effect distillation and multi-stage flash distillation still comprise an important portion of the world’s desalination capacity. [...] Read more.
Reverse osmosis is the leading technology for desalination of brackish water and seawater, important for solving the growing problems of fresh water supply. Thermal technologies such as multi-effect distillation and multi-stage flash distillation still comprise an important portion of the world’s desalination capacity. They consume substantial amounts of energy, generally obtained from fossil fuels, due to their low efficiency. Hybridization is a strategy that seeks to reduce the weaknesses and enhance the advantages of each element that makes it up. This paper introduces a review of the most recent publications on hybridizations between reverse osmosis and thermal desalination technologies, as well as their integration with renewable energies as a requirement to decarbonize desalination processes. Different configurations provide improvements in key elements of the system to reduce energy consumption, brine production, and contamination, while improving product quality and production rate. A combination of renewable sources and use of energy and water storage systems allow for improving the reliability of hybrid systems. Full article
(This article belongs to the Special Issue Innovative Technologies for Lower Energy Consumption in Desalination and Water Reuse)
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