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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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25 pages, 8285 KB  
Article
Predicting Inflow Rate of the Soyang River Dam Using Deep Learning Techniques
by Sangwon Lee and Jaekwang Kim
Water 2021, 13(17), 2447; https://doi.org/10.3390/w13172447 - 6 Sep 2021
Cited by 21 | Viewed by 4445
Abstract
The Soyang Dam, the largest multipurpose dam in Korea, faces water resource management challenges due to global warming. Global warming increases the duration and frequency of days with high temperatures and extreme precipitation events. Therefore, it is crucial to accurately predict the inflow [...] Read more.
The Soyang Dam, the largest multipurpose dam in Korea, faces water resource management challenges due to global warming. Global warming increases the duration and frequency of days with high temperatures and extreme precipitation events. Therefore, it is crucial to accurately predict the inflow rate for water resource management because it helps plan for flood, drought, and power generation in the Seoul metropolitan area. However, the lack of hydrological data for the Soyang River Dam causes a physical-based model to predict the inflow rate inaccurately. This study uses nearly 15 years of meteorological, dam, and weather warning data to overcome the lack of hydrological data and predict the inflow rate over two days. In addition, a sequence-to-sequence (Seq2Seq) mechanism combined with a bidirectional long short-term memory (LSTM) is developed to predict the inflow rate. The proposed model exhibits state-of-the-art prediction accuracy with root mean square error (RMSE) of 44.17 m3/s and 58.59 m3/s, mean absolute error (MAE) of 14.94 m3/s and 17.11 m3/s, and Nash–Sutcliffe efficiency (NSE) of 0.96 and 0.94, for forecasting first and second day, respectively. Full article
(This article belongs to the Section Hydrology)
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15 pages, 2123 KB  
Article
Dual Benefit of Rainwater Harvesting—High Temporal-Resolution Stochastic Modelling
by Ofer Snir and Eran Friedler
Water 2021, 13(17), 2415; https://doi.org/10.3390/w13172415 - 2 Sep 2021
Cited by 8 | Viewed by 8123
Abstract
The objective of the presented study was to develop a high-temporal-resolution stochastic rainwater harvesting (RWH) model for assessing the dual benefits of RWH: potable water savings and runoff reduction. Model inputs of rainfall and water demand are used in a stochastic manner, maintaining [...] Read more.
The objective of the presented study was to develop a high-temporal-resolution stochastic rainwater harvesting (RWH) model for assessing the dual benefits of RWH: potable water savings and runoff reduction. Model inputs of rainfall and water demand are used in a stochastic manner, maintaining their natural pattern, while generating realistic noise and temporal variability. The dynamic model solves a mass-balance equation for the rainwater tank, while logging all inflows and outflows from it for post-simulation analysis. The developed model can simulate various building sizes, roof areas, rainwater tank volumes, controlled release policies, and time periods, providing a platform for assessing short- and long-term benefits. Standard passive rainwater harvesting operation and real-time control policies (controlled release) are demonstrated for a 40-apartment building with rainfall data typical for a Mediterranean climate, showing the system’s ability to supply water for non-potable uses, while reducing runoff volumes and flows, with the latter significantly improved when water is intentionally released from the tank prior to an expected overflow. The model could be used to further investigate the effects of rainwater harvesting on the urban water cycle, by coupling it with an urban drainage model and simulating the operation of a distributed network of micro-reservoirs that supply water and mitigate floods. Full article
(This article belongs to the Section Urban Water Management)
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20 pages, 5190 KB  
Article
Hydrological Responses of Watershed to Historical and Future Land Use Land Cover Change Dynamics of Nashe Watershed, Ethiopia
by Megersa Kebede Leta, Tamene Adugna Demissie and Jens Tränckner
Water 2021, 13(17), 2372; https://doi.org/10.3390/w13172372 - 29 Aug 2021
Cited by 56 | Viewed by 7452
Abstract
Land use land cover (LULC) change is the crucial driving force that affects the hydrological processes of a watershed. The changes of LULC have an important influence and are the main factor for monitoring the water balances. The assessment of LULC change is [...] Read more.
Land use land cover (LULC) change is the crucial driving force that affects the hydrological processes of a watershed. The changes of LULC have an important influence and are the main factor for monitoring the water balances. The assessment of LULC change is indispensable for sustainable development of land and water resources. Understanding the watershed responses to environmental changes and impacts of LULC classes on hydrological components is vigorous for planning water resources, land resource utilization, and hydrological balance sustaining. In this study, LULC effects on hydrological parameters of the Nashe watershed, Blue Nile River Basin are investigated. For this, historical and future LULC change scenarios in the Nashe watershed are implemented into a calibrated Soil and Water Assessment Tool (SWAT) model. Five LULC scenarios have been developed that represent baseline, current, and future periods corresponding to the map of 1990, 2005, 2019, 2035, and 2050. The predicted increase of agricultural and urban land by decreasing mainly forest land will lead till 2035 to an increase of 2.33% in surface runoff and a decline in ground water flow, lateral flow, and evapotranspiration. Between 2035 and 2050, a gradual increase of grass land and range land could mitigate the undesired tendency. The applied combination of LULC prognosis with process-based hydrologic modeling provide valuable data about the current and future understanding of variation in hydrological parameters and assist concerned bodies to improve land and water management in formulating approaches to minimize the conceivable increment of surface runoff. Full article
(This article belongs to the Special Issue Hydrological Processes in Small Catchments—Runoff and Sediment Yield in Changing Environment)
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29 pages, 8889 KB  
Article
Evaluation of Pollutant Removal Efficiency by Small-Scale Nature-Based Solutions Focusing on Bio-Retention Cells, Vegetative Swale and Porous Pavement
by Anik Dutta, Arlex Sanchez Torres and Zoran Vojinovic
Water 2021, 13(17), 2361; https://doi.org/10.3390/w13172361 - 28 Aug 2021
Cited by 23 | Viewed by 8287
Abstract
Rapid urbanization, aging infrastructure, and changes in rainfall patterns linked to climate change have brought considerable challenges to water managers around the world. Impacts from such drivers are likely to increase even further unless the appropriate actions are put in place. Floods, landslides, [...] Read more.
Rapid urbanization, aging infrastructure, and changes in rainfall patterns linked to climate change have brought considerable challenges to water managers around the world. Impacts from such drivers are likely to increase even further unless the appropriate actions are put in place. Floods, landslides, droughts and water pollution are just a few examples of such impacts and their corresponding consequences are in many cases devastating. At the same time, it has become a well-accepted fact that traditional (i.e., grey infrastructure) measures are no longer effective in responding to such challenges. Nature-based solutions (NBS) have emerged as a new response towards hydro-meteorological risk reduction and the results obtained to date are encouraging. However, their application has been mainly in the area of water quantity management with few studies that report on their efficiency to deal with water quality aspects. These solutions are based on replicating natural phenomena and processes to solve such problems. The present paper addresses the question of three NBS systems, namely, bio-retention cells, vegetative swales and porous pavements, for the removal of total suspended solids (TSS), total nitrogen (TN) and total phosphorus (TP) when applied in different configurations (single or networked). The results presented in this paper aim to advance the understanding of their performances during varying rainfall patterns and configurations and their potential application conditions. Full article
(This article belongs to the Special Issue Hydrologic and Water Quality Performance of Stormwater Best Management Practices)
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24 pages, 3607 KB  
Article
Removal of Pharmaceuticals from Wastewater: Analysis of the Past and Present Global Research Activities
by Juan Carlos Leyva-Díaz, Ana Batlles-delaFuente, Valentín Molina-Moreno, Jorge Sánchez Molina and Luis J. Belmonte-Ureña
Water 2021, 13(17), 2353; https://doi.org/10.3390/w13172353 - 27 Aug 2021
Cited by 18 | Viewed by 6933
Abstract
Water pollution is a worldwide problem. Water consumption increases at a faster rate than population and this leads to a higher pollution rate. Sustainable Development Goals (SDG) include proposals aimed at ensuring the availability of clean water and its sustainable management (Goal 6), [...] Read more.
Water pollution is a worldwide problem. Water consumption increases at a faster rate than population and this leads to a higher pollution rate. Sustainable Development Goals (SDG) include proposals aimed at ensuring the availability of clean water and its sustainable management (Goal 6), as well as the conservation and sustainable use of oceans and seas. The current trend consists in trying to reconcile economic growth with sustainability, avoiding the negative externalities for the environment generated by human activity. More specifically, the objective of this article is to present the evolution of the research regarding the removal of polluting pharmaceuticals that are discharged into wastewater. To do that, a bibliometric analysis of 2938 articles comprising the period 1979–2020 has been carried out. This analysis includes productivity indicators in the scientific field: journals, authors, research institutions and countries. In addition, keyword analysis allows the identification of four main axes of the research regarding the removal of pharmaceutical residues found in wastewater. The first group of articles is aimed at identifying the pharmaceuticals present in polluting effluents. The second and third groups of articles focus on presenting the procedures that enable the treatment of emerging contaminants, either from a biological point of view (second group) or a physicochemical point of view (third group). The fourth group refers to water quality and its possibilities to be reused. Finally, there is a growing trend of worldwide scientific publications, which justifies the importance of polluting residues management, especially those of pharmaceutical origin, in order to achieve a more sustainable society. Full article
(This article belongs to the Special Issue Biological Treatments for the Removal of Contaminants of Emerging Concern from Wastewater)
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19 pages, 9487 KB  
Article
Future Changes in Precipitation Extremes over East Africa Based on CMIP6 Models
by Brian Ayugi, Victor Dike, Hamida Ngoma, Hassen Babaousmail, Richard Mumo and Victor Ongoma
Water 2021, 13(17), 2358; https://doi.org/10.3390/w13172358 - 27 Aug 2021
Cited by 85 | Viewed by 9454
Abstract
This paper presents an analysis of projected precipitation extremes over the East African region. The study employs six indices defined by the Expert Team on Climate Change Detection Indices to evaluate extreme precipitation. Observed datasets and Coupled Model Intercomparison Project Phase six (CMIP6) [...] Read more.
This paper presents an analysis of projected precipitation extremes over the East African region. The study employs six indices defined by the Expert Team on Climate Change Detection Indices to evaluate extreme precipitation. Observed datasets and Coupled Model Intercomparison Project Phase six (CMIP6) simulations are employed to assess the changes during the two main rainfall seasons: March to May (MAM) and October to December (OND). The results show an increase in consecutive dry days (CDD) and decrease in consecutive wet days (CWD) towards the end of the 21st century (2081–2100) relative to the baseline period (1995–2014) in both seasons. Moreover, simple daily intensity (SDII), very wet days (R95 p), very heavy precipitation >20 mm (R20 mm), and total wet-day precipitation (PRCPTOT) demonstrate significant changes during OND compared to the MAM season. The spatial variation for extreme incidences shows likely intensification over Uganda and most parts of Kenya, while a reduction is observed over the Tanzania region. The increase in projected extremes may pose a serious threat to the sustainability of societal infrastructure and ecosystem wellbeing. The results from these analyses present an opportunity to understand the emergence of extreme events and the capability of model outputs from CMIP6 in estimating the projected changes. More studies are recommended to examine the underlying physical features modulating the occurrence of extreme incidences projected for relevant policies. Full article
(This article belongs to the Special Issue Hydrological Extremes under Climate Change and Socioeconomic Developments in Developing Countries)
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18 pages, 15053 KB  
Article
Flood Disaster Risk Perception and Urban Households’ Flood Disaster Preparedness: The Case of Accra Metropolis in Ghana
by Qi Yin, Gideon Ntim-Amo, Ruiping Ran, Dingde Xu, Stephen Ansah, Jinfu Hu and Hong Tang
Water 2021, 13(17), 2328; https://doi.org/10.3390/w13172328 - 25 Aug 2021
Cited by 46 | Viewed by 11937
Abstract
Flood disaster has gained global attention due to the huge impact it has on human lives, economies, and sustainable environments. Flood disaster preparedness, which can significantly be influenced by disaster risk perception, has been highlighted as an effective way to manage flood disaster [...] Read more.
Flood disaster has gained global attention due to the huge impact it has on human lives, economies, and sustainable environments. Flood disaster preparedness, which can significantly be influenced by disaster risk perception, has been highlighted as an effective way to manage flood disaster risk, as many other means have proved futile, yet no study has attempted using multiple dimensions to analyze this relationship in Ghana. Therefore, this study, using a survey of 369 households in the most flood-prone region, Accra Metropolis, analyzed the influence of flood disaster risk perception on urban households’ flood disaster preparedness. Based on the Protective Action Decision Model, the empirical models were constructed and estimated using the Tobit and binary logistic regression models. The results show that the majority of households (60.16%) were unprepared for flood disasters, and the perception of flood disaster risk and the sustainability risk posed by floods significantly affect flood disaster preparedness behaviours of households in a positive direction. The total number of flood disaster preparedness behaviours adopted was significantly related to probability, the threat to lives, sense of worry, and sustainability risk perceptions. Finally, income, education, and house ownership, among other household and individual characteristics, had significant positive effects on preparations for flood disasters. These findings suggest that effective policies to mitigate flood disasters must incorporate risk communication to boost households’ flood disaster preparedness. Full article
(This article belongs to the Special Issue Sustainable Development and Disaster Risk Reduction)
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27 pages, 5700 KB  
Article
A New Framework for Modelling Fine Sediment Transport in Rivers Includes Flocculation to Inform Reservoir Management in Wildfire Impacted Watersheds
by Micheal Stone, Bommanna G. Krishnappan, Uldis Silins, Monica B. Emelko, Chris H. S. Williams, Adrian L. Collins and Sheena A. Spencer
Water 2021, 13(17), 2319; https://doi.org/10.3390/w13172319 - 24 Aug 2021
Cited by 15 | Viewed by 6013
Abstract
Fine-grained cohesive sediment is the primary vector for nutrient and contaminant redistribution through aquatic systems and is a critical indicator of land disturbance. A critical limitation of most existing sediment transport models is that they assume that the transport characteristics of fine sediment [...] Read more.
Fine-grained cohesive sediment is the primary vector for nutrient and contaminant redistribution through aquatic systems and is a critical indicator of land disturbance. A critical limitation of most existing sediment transport models is that they assume that the transport characteristics of fine sediment can be described using the same approaches that are used for coarse-grained non-cohesive sediment, thereby ignoring the tendency of fine sediment to flocculate. Here, a modelling framework to simulate flow and fine sediment transport in the Crowsnest River, the Castle River, the Oldman River and the Oldman Reservoir after the 2003 Lost Creek wildfire in Alberta, Canada was developed and validated. It is the first to include explicit description of fine sediment deposition/erosion processes as a function of bed shear stress and the flocculation process. This framework integrates four existing numerical models: MOBED, RIVFLOC, RMA2 and RMA4 using river geometry, flow, fine suspended sediment characteristics and bathymetry data. Sediment concentration and particle size distributions computed by RIVFLOC were used as the upstream boundary condition for the reservoir dispersion model RMA4. The predicted particle size distributions and mass of fine river sediment deposited within various sections of the reservoir indicate that most of the fine sediment generated by the upstream disturbance deposits in the reservoir. Deposition patterns of sediment from wildfire-impacted landscapes were different than those from unburned landscapes because of differences in settling behaviour. These differences may lead to zones of relatively increased internal loading of phosphorus to reservoir water columns, thereby increasing the potential for algae proliferation. In light of the growing threats to water resources globally from wildfire, the generic framework described herein can be used to model propagation of fine river sediment and associated nutrients or contaminants to reservoirs under different flow conditions and land use scenarios. The framework is thereby a valuable tool to support decision making for water resources management and catchment planning. Full article
(This article belongs to the Special Issue Modelling of River Flows, Sediment and Contaminants Transport)
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20 pages, 4309 KB  
Article
Monitoring Land Use Changes and Their Future Prospects Using GIS and ANN-CA for Perak River Basin, Malaysia
by Muhammad Talha Zeshan, Muhammad Raza Ul Mustafa and Mohammed Feras Baig
Water 2021, 13(16), 2286; https://doi.org/10.3390/w13162286 - 21 Aug 2021
Cited by 51 | Viewed by 8959
Abstract
Natural landscapes have changed significantly through anthropogenic activities, particularly in areas that are severely impacted by climate change and population expansion, such as countries in Southeast Asia. It is essential for sustainable development, particularly efficient water management practices, to know about the impact [...] Read more.
Natural landscapes have changed significantly through anthropogenic activities, particularly in areas that are severely impacted by climate change and population expansion, such as countries in Southeast Asia. It is essential for sustainable development, particularly efficient water management practices, to know about the impact of land use and land cover (LULC) changes. Geographic information systems (GIS) and remote sensing were used for monitoring land use changes, whereas artificial neural network cellular automata (ANN-CA) modeling using quantum geographic information systems (QGIS) was performed for prediction of LULC changes. This study investigated the changes in LULC in the Perak River basin for the years 2000, 2010, and 2020. The study also provides predictions of future changes for the years 2030, 2040, and 2050. Landsat satellite images were utilized to monitor the land use changes. For the classification of Landsat images, maximum-likelihood supervised classification was implemented. The broad classification defines four main classes in the study area, including (i) waterbodies, (ii) agricultural lands, (iii) barren and urban lands, and (iv) dense forests. The outcomes revealed a considerable reduction in dense forests from the year 2000 to 2020, whereas a substantial increase in barren lands (up to 547.39 km2) had occurred by the year 2020, while urban land use has seen a rapid rise. The kappa coefficient was used to assess the validity of classified images, with an overall kappa coefficient of 0.86, 0.88, and 0.91 for the years 2000, 2010, and 2020, respectively. In addition, ANN-CA simulation results predicted that barren and urban lands will expand in the future at the expense of other classes in the years 2030, 2040, and 2050. However, a considerable decrease will occur in the area of dense forests in the simulated years. The study successfully presents LULC changes and future predictions highlighting significant pattern of land use change in the Perak River basin. This information could be helpful for land use administration and future planning in the region. Full article
(This article belongs to the Section Hydrology)
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27 pages, 5870 KB  
Review
Marine Seagrasses Transplantation in Confined and Coastal Adriatic Environments: Methods and Results
by Daniele Curiel, Sandra Kraljević Pavelić, Agata Kovačev, Chiara Miotti and Andrea Rismondo
Water 2021, 13(16), 2289; https://doi.org/10.3390/w13162289 - 21 Aug 2021
Cited by 11 | Viewed by 5388
Abstract
The anthropogenic pressures of the twentieth century have seriously endangered the Mediterranean coastal zone; as a consequence, marine seagrass habitats have strongly retreated, mostly those of Posidonia oceanica. For this reason, over time, restoration programs have been put in place through transplantation [...] Read more.
The anthropogenic pressures of the twentieth century have seriously endangered the Mediterranean coastal zone; as a consequence, marine seagrass habitats have strongly retreated, mostly those of Posidonia oceanica. For this reason, over time, restoration programs have been put in place through transplantation activities, with different success. These actions have also been conducted with other Mediterranean marine seagrasses. The results of numerous transplanting operations conducted in the Northern Adriatic Sea and lagoons with Cymodocea nodosa, Zostera marina and Z. noltei and in the Central and Southern Adriatic Sea with P. oceanica (only within the project Interreg SASPAS), are herein presented and compared, taking also into account the presence of extensive meadows of C. nodosa, Z. marina and Z. noltei, along the North Adriatic coasts and lagoons. Full article
(This article belongs to the Special Issue Restore Degraded Marine Coastal Areas in the Mediterranean Sea)
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13 pages, 5136 KB  
Article
Numerical Investigation of Surge Waves Generated by Submarine Debris Flows
by Zili Dai, Jinwei Xie, Shiwei Qin and Shuyang Chen
Water 2021, 13(16), 2276; https://doi.org/10.3390/w13162276 - 20 Aug 2021
Cited by 6 | Viewed by 3355
Abstract
Submarine debris flows and their generated waves are common disasters in Nature that may destroy offshore infrastructure and cause fatalities. As the propagation of submarine debris flows is complex, involving granular material sliding and wave generation, it is difficult to simulate the process [...] Read more.
Submarine debris flows and their generated waves are common disasters in Nature that may destroy offshore infrastructure and cause fatalities. As the propagation of submarine debris flows is complex, involving granular material sliding and wave generation, it is difficult to simulate the process using conventional numerical models. In this study, a numerical model based on the smoothed particle hydrodynamics (SPH) algorithm is proposed to simulate the propagation of submarine debris flow and predict its generated waves. This model contains the Bingham fluid model for granular material, the Newtonian fluid model for the ambient water, and a multiphase granular flow algorithm. Moreover, a boundary treatment technique is applied to consider the repulsive force from the solid boundary. Underwater rigid block slide and underwater sand flow were simulated as numerical examples to verify the proposed SPH model. The computed wave profiles were compared with the observed results recorded in references. The good agreement between the numerical results and experimental data indicates the stability and accuracy of the proposed SPH model. Full article
(This article belongs to the Special Issue Mechanism and Prevention of Debris Flow Disaster)
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29 pages, 13826 KB  
Article
Can Managed Aquifer Recharge Overcome Multiple Droughts?
by Mengqi Zhao, Jan Boll, Jennifer C. Adam and Allyson Beall King
Water 2021, 13(16), 2278; https://doi.org/10.3390/w13162278 - 20 Aug 2021
Cited by 10 | Viewed by 4274
Abstract
Frequent droughts, seasonal precipitation, and growing agricultural water demand in the Yakima River Basin (YRB), located in Washington State, increase the challenges of optimizing water provision for agricultural producers. Increasing water storage through managed aquifer recharge (MAR) can potentially relief water stress from [...] Read more.
Frequent droughts, seasonal precipitation, and growing agricultural water demand in the Yakima River Basin (YRB), located in Washington State, increase the challenges of optimizing water provision for agricultural producers. Increasing water storage through managed aquifer recharge (MAR) can potentially relief water stress from single and multi-year droughts. In this study, we developed an aggregated water resources management tool using a System Dynamics (SD) framework for the YRB and evaluated the MAR implementation strategy and the effectiveness of MAR in alleviating drought impacts on irrigation reliability. The SD model allocates available water resources to meet instream target flows, hydropower demands, and irrigation demand, based on system operation rules, irrigation scheduling, water rights, and MAR adoption. Our findings suggest that the adopted infiltration area for MAR is one of the main factors that determines the amount of water withdrawn and infiltrated to the groundwater system. The implementation time frame is also critical in accumulating MAR entitlements for single-year and multi-year droughts mitigation. In addition, adoption behaviors drive a positive feedback that MAR effectiveness on drought mitigation will encourage more MAR adoptions in the long run. MAR serves as a promising option for water storage management and a long-term strategy for MAR implementation can improve system resilience to unexpected droughts. Full article
(This article belongs to the Special Issue Water Resources Systems in a Changing World: Planning and Adaptation)
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37 pages, 14478 KB  
Article
Spatial Prediction of Groundwater Potentiality in Large Semi-Arid and Karstic Mountainous Region Using Machine Learning Models
by Mustapha Namous, Mohammed Hssaisoune, Biswajeet Pradhan, Chang-Wook Lee, Abdullah Alamri, Abdenbi Elaloui, Mohamed Edahbi, Samira Krimissa, Hasna Eloudi, Mustapha Ouayah, Hicham Elhimer and Tarik Tagma
Water 2021, 13(16), 2273; https://doi.org/10.3390/w13162273 - 19 Aug 2021
Cited by 48 | Viewed by 4897
Abstract
The drinking and irrigation water scarcity is a major global issue, particularly in arid and semi-arid zones. In rural areas, groundwater could be used as an alternative and additional water supply source in order to reduce human suffering in terms of water scarcity. [...] Read more.
The drinking and irrigation water scarcity is a major global issue, particularly in arid and semi-arid zones. In rural areas, groundwater could be used as an alternative and additional water supply source in order to reduce human suffering in terms of water scarcity. In this context, the purpose of the present study is to facilitate groundwater potentiality mapping via spatial-modelling techniques, individual and ensemble machine-learning models. Random forest (RF), logistic regression (LR), decision tree (DT) and artificial neural networks (ANNs) are the main algorithms used in this study. The preparation of groundwater potentiality maps was assembled into 11 ensembles of models. Overall, about 374 groundwater springs was identified and inventoried in the mountain area. The spring inventory data was randomly divided into training (75%) and testing (25%) datasets. Twenty-four groundwater influencing factors (GIFs) were selected based on a multicollinearity test and the information gain calculation. The results of the groundwater potentiality mapping were validated using statistical measures and the receiver operating characteristic curve (ROC) method. Finally, a ranking of the 15 models was achieved with the prioritization rank method using the compound factor (CF) method. The ensembles of models are the most stable and suitable for groundwater potentiality mapping in mountainous aquifers compared to individual models based on success and prediction rate. The most efficient model using the area under the curve validation method is the RF-LR-DT-ANN ensemble of models. Moreover, the results of the prioritization rank indicate that the best models are the RF-DT and RF-LR-DT ensembles of models. Full article
(This article belongs to the Special Issue Geo-Environmental Approaches for the Analysis and Assessment of Groundwater Resources at Catchment-Scale)
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17 pages, 3439 KB  
Article
A Spatial Integrated SLR Adaptive Management Plan Framework (SISAMP) toward Sustainable Coasts
by Lida Davar, Gary Griggs, Afshin Danehkar, Abdolrassoul Salmanmahiny, Hossein Azarnivand and Babak Naimi
Water 2021, 13(16), 2263; https://doi.org/10.3390/w13162263 - 19 Aug 2021
Cited by 8 | Viewed by 4480
Abstract
Sea-level rise (SLR) is known as a central part of the Earth’s response to human-induced global warming and is projected to continue to rise over the twenty-first century and beyond. The importance of coastal areas for both human and natural systems has led [...] Read more.
Sea-level rise (SLR) is known as a central part of the Earth’s response to human-induced global warming and is projected to continue to rise over the twenty-first century and beyond. The importance of coastal areas for both human and natural systems has led researchers to conduct extensive studies on coastal vulnerability to SLR impacts and develop adaptation options to cope with rising sea level. Investigations to date have focused mostly on developed and highly populated coasts, as well as diverse ecosystems including tidal salt marshes and mangroves. As a result, there is less information on vulnerability and adaptation of less-developed and developing coasts to sea-level rise and its associated impacts. Hence, this research aimed at outlining an appropriate coastal management framework to adapt to SLR on the coasts that are in the early stage of development. A coastal area with a low level of development, located in southern Iran along the Gulf of Oman, was selected as a case study. The types of lands exposed to the high-end estimates of SLR by 2100 were identified and used as the primary criteria in determining the practical adaptation approaches for developing coasts. The result of coastal exposure assessment showed that, of five exposed land cover types, bare land, which is potentially considered for development, has the highest percentage of exposure to future sea-level rise. In order to protect the exposed coastal lands from future development and increase adaptive capacity of coastal systems, we developed a Spatial Integrated SLR Adaptive Management Plan Framework (SISAMP) based on an exposure reduction approach. Spatial land management tools and coastal exposure assessment models along with three other key components were integrated into the proposed conceptual framework to reduce coastal vulnerability through minimizing exposure of coastal communities to SLR-induced impacts. This adaptation plan provides a comprehensive approach for sustainable coastal management in a changing climate, particularly on developing coasts. Full article
(This article belongs to the Special Issue Adaptation to Coastal Climate Change and Sea-Level Rise)
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22 pages, 15332 KB  
Article
Integration of Water Quality Indices and Multivariate Modeling for Assessing Surface Water Quality in Qaroun Lake, Egypt
by Mohamed Gad, Magda M. Abou El-Safa, Mohamed Farouk, Hend Hussein, Ashwaq M. Alnemari, Salah Elsayed, Moataz M. Khalifa, Farahat S. Moghanm, Ebrahem M. Eid and Ali H. Saleh
Water 2021, 13(16), 2258; https://doi.org/10.3390/w13162258 - 18 Aug 2021
Cited by 91 | Viewed by 6093
Abstract
Water quality has deteriorated in recent years as a result of rising population and unplanned development, impacting ecosystem health. The water quality parameters of Qaroun Lake are contaminated to varying degrees, particularly for aquatic life consumption. For that, the objective of this work [...] Read more.
Water quality has deteriorated in recent years as a result of rising population and unplanned development, impacting ecosystem health. The water quality parameters of Qaroun Lake are contaminated to varying degrees, particularly for aquatic life consumption. For that, the objective of this work is to improve the assessments of surface water quality and to determine the different geo-environmental parameters affecting the lake environmental system in Qaroun Lake utilizing the weighted arithmetic water quality index (WAWQI) and four pollution indices (heavy metal pollution index (HPI), metal index (MI), contamination index (Cd), and pollution index (PI), that are enhanced by multivariate analyses as cluster analysis (CA), principal component analysis (PCA), and support vector machine regression (SVMR). Surface water samples were collected at 16 different locations from the lake during years 2018 and 2019. Thirteen physiochemical parameters were measured and used to calculate water quality indices (WQIs). The WQIs of Qaroun Lake such WAWQI, HPI, MI, Cd, PI revealed a different degree of contamination, with respect to aquatic life utilization. The WQIs result revealed that surface water in the lake is unsuitable, high polluted, and seriously affected by pollution for an aquatic environment. The PI findings revealed that surface water samples of Qaroun Lake were significantly impacted by Al, moderately affected by Cd and Cu, and while slightly affected by Zn due to uncontrolled releases of domestic and industrial wastewater. Furthermore, increasing salinity accelerates the deterioration of the lake aquatic environment. Therefore, sewage and drainage wastewater should be treated before discharging into the lake. The SVMR models based on physiochemical parameters presented the highest performance as an alternative method to predict the WQIs. For example, the calibration (Val.) and the validation (Val.) models performed best in assessing the WQIs with R2 (0.99) and with R2 (0.97–0.99), respectively. Finally, a combination of WQIs, CA, PCA, and SVMR approaches could be employed to assess surface water quality in Qaroun Lake. Full article
(This article belongs to the Section Water Quality and Contamination)
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26 pages, 5190 KB  
Article
Multi-Step Calibration Approach for SWAT Model Using Soil Moisture and Crop Yields in a Small Agricultural Catchment
by Francis Kilundu Musyoka, Peter Strauss, Guangju Zhao, Raghavan Srinivasan and Andreas Klik
Water 2021, 13(16), 2238; https://doi.org/10.3390/w13162238 - 17 Aug 2021
Cited by 33 | Viewed by 7900
Abstract
The quantitative prediction of hydrological components through hydrological models could serve as a basis for developing better land and water management policies. This study provides a comprehensive step by step modelling approach for a small agricultural watershed using the SWAT model. The watershed [...] Read more.
The quantitative prediction of hydrological components through hydrological models could serve as a basis for developing better land and water management policies. This study provides a comprehensive step by step modelling approach for a small agricultural watershed using the SWAT model. The watershed is situated in Petzenkirchen in the western part of Lower Austria and has total area of 66 hectares. At present, 87% of the catchment area is arable land, 5% is used as pasture, 6% is forested and 2% is paved. The calibration approach involves a sequential calibration of the model starting from surface runoff, and groundwater flow, followed by crop yields and then soil moisture, and finally total streamflow and sediment yields. Calibration and validation are carried out using the r-package SWATplusR. The impact of each calibration step on sediment yields and total streamflow is evaluated. The results of this approach are compared with those of the conventional model calibration approach, where all the parameters governing various hydrological processes are calibrated simultaneously. Results showed that the model was capable of successfully predicting surface runoff, groundwater flow, soil profile water content, total streamflow and sediment yields with Nash-Sutcliffe efficiency (NSE) of greater than 0.75. Crop yields were also well simulated with a percent bias (PBIAS) ranging from −17% to 14%. Surface runoff calibration had the highest impact on streamflow output, improving NSE from 0.39 to 0.77. The step-wise calibration approach performed better for streamflow prediction than the simultaneous calibration approach. The results of this study show that the step-wise calibration approach is more accurate, and provides a better representation of different hydrological components and processes than the simultaneous calibration approach. Full article
(This article belongs to the Special Issue Modelling of Soil Conservation, Soil Erosion and Sediment Transport)
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17 pages, 3987 KB  
Article
Reclaimed Water for Vineyard Irrigation in a Mediterranean Context: Life Cycle Environmental Impacts, Life Cycle Costs, and Eco-Efficiency
by Kledja Canaj, Domenico Morrone, Rocco Roma, Francesca Boari, Vito Cantore and Mladen Todorovic
Water 2021, 13(16), 2242; https://doi.org/10.3390/w13162242 - 17 Aug 2021
Cited by 32 | Viewed by 4903
Abstract
The agricultural sector in the Mediterranean region, is increasingly using reclaimed water as an additional source for irrigation. However, there is a limited number of case studies about product-based life cycle analysis to ensure that the overall benefits of reclaimed water do indeed [...] Read more.
The agricultural sector in the Mediterranean region, is increasingly using reclaimed water as an additional source for irrigation. However, there is a limited number of case studies about product-based life cycle analysis to ensure that the overall benefits of reclaimed water do indeed outweigh the impacts. The Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methods are used in this study to investigate the environmental impacts and costs of vineyard cropping systems when tertiary reclaimed water is used as a supplementary source of irrigation water (integrated system). The conventional production system utilizing 100% groundwater was used as a reference system. As a proxy for sustainability, eco-efficiency, which combines economic and environmental performance, was assessed. The LCA revealed that the integrated system could reduce the net environmental impact by 23.8% due to lower consumption of irrigation water (−50%), electricity (−27.7%), and chemical fertilizers (−22.6%). Nevertheless, trade-offs between economics and the environment occurred as an integrated system is associated with higher life cycle costs and lower economic returns due to lower crop yield (−9.1%). The combined eco-efficiency assessment (ratio of economic value added to total environmental impact) revealed that the integrated system outperformed in terms of eco-efficiency by 12.6% due to lower environmental impacts. These results confirmed that reclaimed water could help to ensure an economically profitable yield with net environmental benefits. Our results provided an up-to-date and consistent life cycle analysis contributing to the creation of a valuable knowledge base for the associated costs and benefits of vineyard cultivation with treated wastewater. Full article
(This article belongs to the Special Issue Climate Smart Irrigation Management for Sustainable Agricultural Cultivation)
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26 pages, 3421 KB  
Review
Desalination: From Ancient to Present and Future
by Andreas N. Angelakis, Mohammad Valipour, Kwang-Ho Choo, Abdelkader T. Ahmed, Alper Baba, Rohitashw Kumar, Gurpal S. Toor and Zhiwei Wang
Water 2021, 13(16), 2222; https://doi.org/10.3390/w13162222 - 16 Aug 2021
Cited by 60 | Viewed by 22662
Abstract
Water is life, and without water, there would be no civilizations and a vacant Earth. Water is considered an abundant natural resource on the earth. Water covers 3/4 of the surface. However, 97% of the available water on the earth is salty oceanic [...] Read more.
Water is life, and without water, there would be no civilizations and a vacant Earth. Water is considered an abundant natural resource on the earth. Water covers 3/4 of the surface. However, 97% of the available water on the earth is salty oceanic water, and only a tiny fraction (3%) is freshwater. This small portion of the available water supplies the needs of humans and animals. However, freshwater exists in underground, rivers, and lakes and is insufficient to cover all the world’s water demands. Thus, water saving, water reuse, rainwater harvesting, stormwater utilization, and desalination are critical for maintaining water supplies for the future of humanity. Desalination has a long history spanning centuries from ancient times to the present. In the last two decades, desalination has been rapidly expanding to meet water needs in stressed water regions of the world. Yet, there are still some problems with its implementation in several areas of the world. This review provides a comprehensive assessment of the history of desalination for wiser and smarter water extraction and uses to sustain and support the water needs of the earth’s inhabitants. Full article
(This article belongs to the Special Issue Water Scarcity: From Ancient to Modern Times and the Future)
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17 pages, 3906 KB  
Article
Laboratory Analysis of Debris Flow Characteristics and Berm Performance
by Kukhyun Ryou, Hyungjoon Chang and Hojin Lee
Water 2021, 13(16), 2223; https://doi.org/10.3390/w13162223 - 16 Aug 2021
Cited by 4 | Viewed by 4028
Abstract
In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental [...] Read more.
In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental flume 1.3 to 1.9 m long, 0.15 m wide, and 0.3 m high was employed to investigate the effects of channel slope and volumetric concentration of sediment with and without the berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities also increased with the flow velocity and flow depth. In addition, the maximum reductions in the runout distance, lateral width, and deposition area were 69.1%, 65.9%, and 93%, respectively, upon berm installation. The results of this study illustrate general debris flow characteristics according to berm installation; the reported relationship magnitudes are specific to the experimental conditions described herein. However, the results of this study contribute to the design of site-specific berms in the future by providing data describing the utility and function of berms in mitigating debris flow. Full article
(This article belongs to the Special Issue Mechanism and Prevention of Debris Flow Disaster)
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20 pages, 1152 KB  
Review
Do Freshwater Fish Eat Microplastics? A Review with A Focus on Effects on Fish Health and Predictive Traits of MPs Ingestion
by Silvia Galafassi, Claudia Campanale, Carmine Massarelli, Vito Felice Uricchio and Pietro Volta
Water 2021, 13(16), 2214; https://doi.org/10.3390/w13162214 - 14 Aug 2021
Cited by 52 | Viewed by 9456
Abstract
Microplastics (MPs) have received increasing attention in the last decade and are now considered among the most concerning emerging pollutants in natural environments. Here, the current knowledge on microplastic ingestion by wild freshwater fish is reviewed with a focus on the identification of [...] Read more.
Microplastics (MPs) have received increasing attention in the last decade and are now considered among the most concerning emerging pollutants in natural environments. Here, the current knowledge on microplastic ingestion by wild freshwater fish is reviewed with a focus on the identification of possible factors leading to the ingestion of MPs and the consequences on fish health. Within the literature, 257 species of freshwater fishes from 32 countries have been documented to ingest MPs. MPs ingestion was found to increase with rising level of urbanization, although a direct correlation with MPs concentration in the surrounding water has not been identified. MPs ingestion was detected in all the published articles, with MPs presence in more than 50% of the specimens analyzed in one study out of two. Together with the digestive tract, MPs were also found in the gills, and there is evidence that MPs can translocate to different tissues of the organism. Strong evidence, therefore, exists that MPs may represent a serious risk for ecosystems, and are a direct danger for human health. Moreover, toxicological effects have also been highlighted in wild catches, demonstrating the importance of this problem and suggesting the need for laboratory experiments more representative of the environmental situation. Full article
(This article belongs to the Special Issue Impacts of Human Activities and Climate Change on Freshwater Fish)
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14 pages, 1889 KB  
Article
Do Single-Component and Mixtures Selected Organic UV Filters Induce Embryotoxic Effects in Zebrafish (Danio rerio)?
by Jana Cahova, Jana Blahova, Lucie Plhalova, Zdenka Svobodova and Caterina Faggio
Water 2021, 13(16), 2203; https://doi.org/10.3390/w13162203 - 13 Aug 2021
Cited by 43 | Viewed by 4614
Abstract
UVs are important ingredients in common cosmetic products (e.g., sunscreens, hairsprays, soap). After their use, they can enter the aquatic ecosystem and negatively affect non-target aquatic organisms. The aim of our study was to evaluate acute embryotoxicity of selected organic UVs 2-phenylbenzimidazole-5-sulfonic acid [...] Read more.
UVs are important ingredients in common cosmetic products (e.g., sunscreens, hairsprays, soap). After their use, they can enter the aquatic ecosystem and negatively affect non-target aquatic organisms. The aim of our study was to evaluate acute embryotoxicity of selected organic UVs 2-phenylbenzimidazole-5-sulfonic acid (PBSA), ethylhexyl methoxycinnamate (EHMC), octocrylene (OC), 4-methylbenzylidene camphor (4-MBC) and benzophenone-3 (BP-3). The chemicals were tested both as a single substance and their mixtures. The types of mixtures were chosen as follows: the combination of OC and 4-MBC; the combination of PBSA, EHMC and BP-3 and the combination of all five UV filters. The embryotoxicity was evaluated using a modified method of the Fish Embryo Acute Toxicity Test-OECD guideline 236 and zebrafish (Danio rerio) was selected as a suitable fish model organism. The toxic effects were studied by assessing mortality, hatching and the occurrence of malformations at 24, 48, 72 and 96 h post fertilization. The obtained results indicate that especially the mixture of OC and 4-MBC presents a potential risk of embryotoxicity for zebrafish due to a significant increase in mortality, which was 41.7% in the experimental group exposed to 10 μg/L at 96 h post fertilization. Based on our results, the most effected sub-lethal endpoints were hatching and malformation (e.g., edema of pericard, bent spine, yolk edema), but with no statistically significant effect. These results differ within groups with single UVs and with their mixtures, suggesting the interaction of these substances when they are exposed together. Full article
(This article belongs to the Special Issue Aquatic Ecotoxicity Assessment)
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15 pages, 5188 KB  
Article
Synthesis and Characterization of Sr-Doped ZnSe Nanoparticles for Catalytic and Biological Activities
by V. Beena, S. L. Rayar, S. Ajitha, Awais Ahmad, Munirah D. Albaqami, Fatmah Ahmed Ali Alsabar and Mika Sillanpää
Water 2021, 13(16), 2189; https://doi.org/10.3390/w13162189 - 11 Aug 2021
Cited by 35 | Viewed by 5040
Abstract
The development of cost-effective and ecofriendly approaches toward water purification and antibacterial activity is a hot research topic in this era. Purposely, strontium-doped zinc selenide (Sr-doped ZnSe) nanoparticles, with different molar ratios of Sr2+ cations (0.01, 0.05, and 0.1), were prepared via [...] Read more.
The development of cost-effective and ecofriendly approaches toward water purification and antibacterial activity is a hot research topic in this era. Purposely, strontium-doped zinc selenide (Sr-doped ZnSe) nanoparticles, with different molar ratios of Sr2+ cations (0.01, 0.05, and 0.1), were prepared via the co-precipitation method, in which sodium borohydride (NaBH4) and 2-mercaptoethanol were employed as reducing and stabilizing agents, respectively. The ZnSe cubic structure expanded by Sr2+ cations was indicated by X-ray diffraction (XRD) analysis. The absorption of the chemical compounds on the surface was observed via Fourier transform infrared (FT-IR) spectroscopy. The optical orientation was measured by ultraviolet–visible diffused reflectance spectroscopy (UV-DRS) analysis. The surface area, morphology, and elemental purity were analyzed using field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive spectroscopy (EDS) analyses. The oxidation state and valency of the synthesized nanoparticles were analyzed using X-ray photoelectron spectroscopy (XPS). Sr-doped ZnSe nanoparticles were investigated for photocatalytic degradation of methyl orange (MO), and their antibacterial potential was investigated against different bacterial strains. The antibacterial activity examined against Staphylococcus aureus and Escherichia coli implied the excellent biological activity of the nanoparticles. Moreover, the Sr-doped ZnSe nanoparticles were evaluated by the successful degradation of methyl orange under visible light irradiation. Therefore, Sr-doped ZnSe nanoparticles have tremendous potential in biological and water remediation fields. Full article
(This article belongs to the Special Issue Advanced Materials and Technologies for Pollution Detection and Environmental Remediation)
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25 pages, 1732 KB  
Review
On the Way to the Fluvial Anthroposphere—Current Limitations and Perspectives of Multidisciplinary Research
by Lukas Werther, Natascha Mehler, Gerrit Jasper Schenk and Christoph Zielhofer
Water 2021, 13(16), 2188; https://doi.org/10.3390/w13162188 - 11 Aug 2021
Cited by 24 | Viewed by 8205
Abstract
Floodplains represent a global hotspot of sensitive socioenvironmental changes and early human forcing mechanisms. In this review, we focus on the environmental conditions of preindustrial floodplains in Central Europe and the fluvial societies that operated there. Due to their high land-use capacity and [...] Read more.
Floodplains represent a global hotspot of sensitive socioenvironmental changes and early human forcing mechanisms. In this review, we focus on the environmental conditions of preindustrial floodplains in Central Europe and the fluvial societies that operated there. Due to their high land-use capacity and the simultaneous necessity of land reclamation and risk minimisation, societies have radically restructured the Central European floodplains. According to the current scientific consensus, up to 95% of Central European floodplains have been extensively restructured or destroyed. Therefore, question arises as to whether or when it is justified to understand Central European floodplains as a ‘Fluvial Anthroposphere’. The case studies available to date show that human-induced impacts on floodplain morphologies and environments and the formation of specific fluvial societies reveal fundamental changes in the medieval and preindustrial modern periods. We aim to contribute to disentangling the questions of when and why humans became a significant controlling factor in Central European floodplain formation, and how humans in interaction with natural processes and other chains of effects have modified floodplains. As a conclusion, we superimpose emerging fields of research concerning the onset of the Fluvial Anthroposphere and provide 10 specific thematic objectives for future multidisciplinary work. Full article
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27 pages, 1878 KB  
Review
Recent Advances of Nanoremediation Technologies for Soil and Groundwater Remediation: A Review
by Motasem Y. D. Alazaiza, Ahmed Albahnasawi, Gomaa A. M. Ali, Mohammed J. K. Bashir, Nadim K. Copty, Salem S. Abu Amr, Mohammed F. M. Abushammala and Tahra Al Maskari
Water 2021, 13(16), 2186; https://doi.org/10.3390/w13162186 - 10 Aug 2021
Cited by 108 | Viewed by 16191
Abstract
Nanotechnology has been widely used in many fields including in soil and groundwater remediation. Nanoremediation has emerged as an effective, rapid, and efficient technology for soil and groundwater contaminated with petroleum pollutants and heavy metals. This review provides an overview of the application [...] Read more.
Nanotechnology has been widely used in many fields including in soil and groundwater remediation. Nanoremediation has emerged as an effective, rapid, and efficient technology for soil and groundwater contaminated with petroleum pollutants and heavy metals. This review provides an overview of the application of nanomaterials for environmental cleanup, such as soil and groundwater remediation. Four types of nanomaterials, namely nanoscale zero-valent iron (nZVI), carbon nanotubes (CNTs), and metallic and magnetic nanoparticles (MNPs), are presented and discussed. In addition, the potential environmental risks of the nanomaterial application in soil remediation are highlighted. Moreover, this review provides insight into the combination of nanoremediation with other remediation technologies. The study demonstrates that nZVI had been widely studied for high-efficiency environmental remediation due to its high reactivity and excellent contaminant immobilization capability. CNTs have received more attention for remediation of organic and inorganic contaminants because of their unique adsorption characteristics. Environmental remediations using metal and MNPs are also favorable due to their facile magnetic separation and unique metal-ion adsorption. The modified nZVI showed less toxicity towards soil bacteria than bare nZVI; thus, modifying or coating nZVI could reduce its ecotoxicity. The combination of nanoremediation with other remediation technology is shown to be a valuable soil remediation technique as the synergetic effects may increase the sustainability of the applied process towards green technology for soil remediation. Full article
(This article belongs to the Special Issue Wastewater Treatment: Current and Future Techniques)
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30 pages, 4992 KB  
Article
Hydrochemical Characterisation of High-Fluoride Groundwater and Development of a Conceptual Groundwater Flow Model Using a Combined Hydrogeological and Hydrochemical Approach on an Active Volcano: Mount Meru, Northern Tanzania
by George Bennett, Jill Van Reybrouck, Ceven Shemsanga, Mary Kisaka, Ines Tomašek, Karen Fontijn, Matthieu Kervyn and Kristine Walraevens
Water 2021, 13(16), 2159; https://doi.org/10.3390/w13162159 - 6 Aug 2021
Cited by 22 | Viewed by 4505
Abstract
This study characterises high-fluoride groundwater in the aquifer system on the flanks of Mount Meru, focusing on parts of the flanks that were only partially or not at all covered by previous research. Additionally, we analyse the impact of rainwater recharge on groundwater [...] Read more.
This study characterises high-fluoride groundwater in the aquifer system on the flanks of Mount Meru, focusing on parts of the flanks that were only partially or not at all covered by previous research. Additionally, we analyse the impact of rainwater recharge on groundwater chemistry by monitoring spring discharges during water sampling. The results show that the main groundwater type in the study area is NaHCO3 alkaline groundwater (average pH = 7.8). High F− values were recorded: in 175 groundwater samples, the concentrations range from 0.15 to 301 mg/L (mean: 21.89 mg/L, median: 9.67 mg/L), with 91% of the samples containing F− values above the WHO health-based guideline for drinking water (1.5 mg/L), whereas 39% of the samples have Na+ concentrations above the WHO taste-based guideline of 200 mg/L. The temporal variability in F− concentrations between different seasons is due to the impact of the local groundwater recharge. We recommend that a detailed ecohydrological study should be carried out for the low-fluoride springs from the high-altitude recharge areas on the eastern and northwestern flanks of Mount Meru inside Arusha National Park. These springs are extracted for drinking purposes. An ecohydrological study is required for the management of these springs and their potential enhanced exploitation to ensure the sustainability of this water extraction practice. Another strategy for obtaining safe drinking water could be to use a large-scale filtering system to remove F− from the groundwater. Full article
(This article belongs to the Special Issue Groundwater Resources Management: Reconciling Demand, High Quality Resources and Sustainability)
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34 pages, 3097 KB  
Article
Closing Water Cycles in the Built Environment through Nature-Based Solutions: The Contribution of Vertical Greening Systems and Green Roofs
by David Pearlmutter, Bernhard Pucher, Cristina S. C. Calheiros, Karin A. Hoffmann, Andreas Aicher, Pedro Pinho, Alessandro Stracqualursi, Alisa Korolova, Alma Pobric, Ana Galvão, Ayça Tokuç, Bilge Bas, Dimitra Theochari, Dragan Milosevic, Emanuela Giancola, Gaetano Bertino, Joana A. C. Castellar, Julia Flaszynska, Makbulenur Onur, Mari Carmen Garcia Mateo, Maria Beatrice Andreucci, Maria Milousi, Mariana Fonseca, Sara Di Lonardo, Veronika Gezik, Ulrike Pitha and Thomas Nehlsadd Show full author list remove Hide full author list
Water 2021, 13(16), 2165; https://doi.org/10.3390/w13162165 - 6 Aug 2021
Cited by 54 | Viewed by 15863
Abstract
Water in the city is typically exploited in a linear process, in which most of it is polluted, treated, and discharged; during this process, valuable nutrients are lost in the treatment process instead of being cycled back and used in urban agriculture or [...] Read more.
Water in the city is typically exploited in a linear process, in which most of it is polluted, treated, and discharged; during this process, valuable nutrients are lost in the treatment process instead of being cycled back and used in urban agriculture or green space. The purpose of this paper is to advance a new paradigm to close water cycles in cities via the implementation of nature-based solutions units (NBS_u), with a particular focus on building greening elements, such as green roofs (GRs) and vertical greening systems (VGS). The hypothesis is that such “circular systems” can provide substantial ecosystem services and minimize environmental degradation. Our method is twofold: we first examine these systems from a life-cycle point of view, assessing not only the inputs of conventional and alternative materials, but the ongoing input of water that is required for irrigation. Secondly, the evapotranspiration performance of VGS in Copenhagen, Berlin, Lisbon, Rome, Istanbul, and Tel Aviv, cities with different climatic, architectural, and sociocultural contexts have been simulated using a verticalized ET0 approach, assessing rainwater runoff and greywater as irrigation resources. The water cycling performance of VGS in the mentioned cities would be sufficient at recycling 44% (Lisbon) to 100% (Berlin, Istanbul) of all accruing rainwater roof–runoff, if water shortages in dry months are bridged by greywater. Then, 27–53% of the greywater accruing in a building could be managed on its greened surface. In conclusion, we address the gaps in the current knowledge and policies identified in the different stages of analyses, such as the lack of comprehensive life cycle assessment studies that quantify the complete “water footprint” of building greening systems. Full article
(This article belongs to the Special Issue Water and Circular Cities)
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18 pages, 3120 KB  
Article
Classification of Aquifer Vulnerability by Using the DRASTIC Index and Geo-Electrical Techniques
by Syed Hassan Iqbal Ahmad Shah, Jianguo Yan, Israr Ullah, Bilal Aslam, Aqil Tariq, Lili Zhang and Faisal Mumtaz
Water 2021, 13(16), 2144; https://doi.org/10.3390/w13162144 - 4 Aug 2021
Cited by 42 | Viewed by 6372
Abstract
Vulnerability analysis in areas vulnerable to anthropogenic pollution has become a key element of sensible resource management and land use planning. This study is intended to estimate aquifer vulnerability using the DRASTIC model and using the vertical electrical sounding (VES) and electrical conductivity [...] Read more.
Vulnerability analysis in areas vulnerable to anthropogenic pollution has become a key element of sensible resource management and land use planning. This study is intended to estimate aquifer vulnerability using the DRASTIC model and using the vertical electrical sounding (VES) and electrical conductivity (EC) outcomes. The model allows for the identification of hydrogeological environments within the scope of the research, based on a composite definition of each environment’s main geological, geoelectrical, and hydrogeological factors. The results from the DRASTIC model were divided into four equal intervals, high, medium, low, and very low drastic index values. The SW area and NE area depict drastic index values from medium to very high, making it the most vulnerable zone in the study area, while the NW and SW areas show low to very low drastic index values. In addition, the results from the VES and EC the freshwater aquifer in the NE area and brackish water in the SE area, while the rest of the area falls into the category of brackish water. Overall, it can be concluded that areas having freshwater assemblages are on the verge of becoming contaminated in the future while the rest of the NW and SW areas constitute less vulnerable zones. The validation conducted for DRASTIC and EC shows a nearly positive correlation. Wastewater treatment policies must be developed throughout the studied region to prevent contamination of the remaining groundwater. Full article
(This article belongs to the Special Issue Protection and Usage of Groundwater)
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13 pages, 2017 KB  
Article
Activated Ailanthus altissima Sawdust as Adsorbent for Removal of Acid Yellow 29 from Wastewater: Kinetics Approach
by Najeeb ur Rahman, Ihsan Ullah, Sultan Alam, Muhammad Sufaid Khan, Luqman Ali Shah, Ivar Zekker, Juris Burlakovs, Anna Kallistova, Nikolai Pimenov, Zane Vincevica-Gaile, Yahya Jani and Mohammad Zahoor
Water 2021, 13(15), 2136; https://doi.org/10.3390/w13152136 - 3 Aug 2021
Cited by 49 | Viewed by 3934
Abstract
In this study, Ailanthus altissima sawdust was chemically activated and characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X rays (EDX), and surface area analyzer. The sawdust was used as an adsorbent for the removal of azo dye; Acid [...] Read more.
In this study, Ailanthus altissima sawdust was chemically activated and characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X rays (EDX), and surface area analyzer. The sawdust was used as an adsorbent for the removal of azo dye; Acid Yellow 29 (AY 29) from wastewater. Different kinetic and equilibrium models were used to calculate the adsorption parameters. Among the applied models, the more suitable model was Freundlich with maximum adsorption capacities of 9.464, 12.798, and 11.46 mg/g at 20 °C, 30 °C, and 40 °C respectively while R2 values close to 1. Moreover, the kinetic data was best fitted in pseudo second order kinetic model with high R2 values approaching to 1. Furthermore, adsorption thermodynamics parameters such as free energy, enthalpy, and entropy were calculated and the adsorption process was found to be exothermic with a value of ∆H° = −9.981 KJ mol−1, spontaneous that was concluded from ΔG° values which were negative (−0.275, −3.422, and −6.171 KJ mol−1 at 20, 30, and 40 °C respectively). A positive entropy change ∆S° with a value of 0.0363 KJ mol−1 indicated the increase disorder during adsorption process. It was concluded that the activated sawdust could be used as a suitable adsorbent for the removal of waste material, especially dyes from polluted waters. Full article
(This article belongs to the Special Issue Efficient Catalytic and Microbial Treatment of Water Pollutants)
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33 pages, 3939 KB  
Article
Supporting Restoration Decisions through Integration of Tree-Ring and Modeling Data: Reconstructing Flow and Salinity in the San Francisco Estuary over the Past Millennium
by Paul H. Hutton, David M. Meko and Sujoy B. Roy
Water 2021, 13(15), 2139; https://doi.org/10.3390/w13152139 - 3 Aug 2021
Cited by 6 | Viewed by 3832
Abstract
This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary [...] Read more.
This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary over the past millennium and compare this characterization with contemporary conditions to better understand the magnitude and seasonality of changes over this time. This work shows that the instrumented flow record spans the range of runoff patterns over the past millennium (averaged over 5, 10, 20 and 100 years), and thus serves as a reasonable basis for planning-level evaluations of historical hydrologic conditions in the estuary. Over annual timescales we show that, although median freshwater flow to the estuary has not changed significantly, it has been more variable over the past century compared to pre-development flow conditions. We further show that the contemporary period is generally associated with greater spring salinity intrusion and lesser summer–fall salinity intrusion relative to the pre-development period. Thus, salinity intrusion in summer and fall months was a common occurrence under pre-development conditions and has been moderated in the contemporary period due to the operations of upstream reservoirs, which were designed to hold winter and spring runoff for release in summer and fall. This work also confirms a dramatic decadal-scale hydrologic shift in the watershed from very wet to very dry conditions during the late 19th and early 20th centuries; while not unprecedented, these shifts have been seen only a few times in the past millennium. This shift resulted in an increase in salinity intrusion in the first three decades of the 20th century, as documented through early records. Population growth and extensive watershed modification during this period exacerbated this underlying hydrologic shift. Putting this shift in the context of other anthropogenic drivers is important in understanding the historical response of the estuary and in setting salinity targets for estuarine restoration. By characterizing the long-term behavior of San Francisco Estuary, this work supports decision-making in the State of California related to flow and salinity management for restoration of the estuarine ecosystem. Full article
(This article belongs to the Special Issue Decision Support Tools for Water Quality Management)
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17 pages, 2812 KB  
Article
Seed Halo-Priming Improves Seedling Vigor, Grain Yield, and Water Use Efficiency of Maize under Varying Irrigation Regimes
by AbdAllah M. El-Sanatawy, Salwa M.A.I. Ash-Shormillesy, Naglaa Qabil, Mohamed F. Awad and Elsayed Mansour
Water 2021, 13(15), 2115; https://doi.org/10.3390/w13152115 - 31 Jul 2021
Cited by 47 | Viewed by 7287
Abstract
Water-deficit stress poses tremendous constraints to sustainable agriculture, particularly under abrupt climate change. Hence, it is crucial to find eco-friendly approaches to ameliorate drought tolerance, especially for sensitive crops such as maize. This study aimed at assessing the impact of seed halo-priming on [...] Read more.
Water-deficit stress poses tremendous constraints to sustainable agriculture, particularly under abrupt climate change. Hence, it is crucial to find eco-friendly approaches to ameliorate drought tolerance, especially for sensitive crops such as maize. This study aimed at assessing the impact of seed halo-priming on seedling vigor, grain yield, and water use efficiency of maize under various irrigation regimes. Laboratory trials evaluated the influence of seed halo-priming using two concentrations of sodium chloride solution, 4000 and 8000 ppm NaCl, versus unprimed seeds on seed germination and seedling vigor parameters. Field trials investigated the impact of halo-priming treatments on maize yield and water use efficiency (WUE) under four irrigation regimes comprising excessive (120% of estimated crop evapotranspiration, ETc), normal (100% ETc), and deficit (80 and 60% ETc) irrigation regimes. Over-irrigation by 20% did not produce significantly more grain yield but considerably reduced WUE. Deficit irrigation (80 and 60%ETc) gradually reduced grain yield and its attributes. Halo-priming treatments, particularly 4000 ppm NaCl, improved uniformity and germination speed, increased germination percentage and germination index, and produced more vigorous seedlings with heavier dry weight compared with unprimed seeds. Under field conditions, the plants originated from halo-primed seeds, especially with 4000 ppm NaCl, had higher grain yield and WUE compared with unprimed seeds under deficit irrigation regimes. The long-lasting stress memory induced by seed halo-priming, particularly with 4000 ppm NaCl, promoted maize seedling establishment, grain yield, and WUE and consequently mitigated the devastating impacts of drought stress. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
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23 pages, 1049 KB  
Review
Use of Electrocoagulation for Treatment of Pharmaceutical Compounds in Water/Wastewater: A Review Exploring Opportunities and Challenges
by Rahat Alam, Mohd Sheob, Bilal Saeed, Saif Ullah Khan, Maryam Shirinkar, Zacharias Frontistis, Farrukh Basheer and Izharul Haq Farooqi
Water 2021, 13(15), 2105; https://doi.org/10.3390/w13152105 - 31 Jul 2021
Cited by 50 | Viewed by 9949
Abstract
Increasing dependency on pharmaceutical compounds including antibiotics, analgesics, antidepressants, and other drugs has threatened the environment as well as human health. Their occurrence, transformation, and fate in the environment are causing significant concerns. Several existing treatment technologies are there with their pros and [...] Read more.
Increasing dependency on pharmaceutical compounds including antibiotics, analgesics, antidepressants, and other drugs has threatened the environment as well as human health. Their occurrence, transformation, and fate in the environment are causing significant concerns. Several existing treatment technologies are there with their pros and cons for the treatment of pharmaceutical wastewater (PWW). Still, electrocoagulation is considered as the modern and decisive technology for treatment. In the EC process, utilizing electricity (AC/DC) and electrodes, contaminants become coagulated with the metal hydroxide and are separated by co-precipitation. The main mechanism is charge neutralization and adsorption of contaminants on the generated flocs. The range of parameters affects the EC process and is directly related to the removal efficiency and its overall operational cost. This process only could be scaled up on the industrial level if process parameters become optimized and energy consumption is reduced. Unfortunately, the removal mechanism of particular pharmaceuticals and complex physiochemical phenomena involved in this process are not fully understood. For this reason, further research and reviews are required to fill the knowledge gap. This review discusses the use of EC for removing pharmaceuticals and focuses on removal mechanism and process parameters, the cost assessment, and the challenges involved in mitigation. Full article
(This article belongs to the Special Issue Application of Electrochemistry in Wastewater Treatment)
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16 pages, 5061 KB  
Article
Scour Features at Wood Bundles
by Simone Pagliara, Deep Roy and Michele Palermo
Water 2021, 13(15), 2118; https://doi.org/10.3390/w13152118 - 31 Jul 2021
Cited by 3 | Viewed by 2545
Abstract
Structures like blunt-nosed chevrons, log deflectors and double-winged log frames help in modifying the flow regime in the channel by concentrating the flow and increasing navigability. Moreover, they create scour pools in the downstream stilling basin, which can be used either as fish [...] Read more.
Structures like blunt-nosed chevrons, log deflectors and double-winged log frames help in modifying the flow regime in the channel by concentrating the flow and increasing navigability. Moreover, they create scour pools in the downstream stilling basin, which can be used either as fish refuge or as an in-stream storage site for previously dredged material. In this respect, the use of wood debris in the channel in the form of wood bundles has gained attention for the ability of these structures to integrate into the surrounding fluvial habitat and to divert the flow partially towards the central part of the channel when placed in curves. Considering the absence of studies dealing with wood bundles as a restoration structure, the aim of this paper is to analyse the scour mechanism and equilibrium scour morphology of wood bundles in straight and curved channels. In doing so, a wide range of hydraulic conditions, structure positions and configurations were tested. Thereafter, dimensional analysis was carried out to derive useful empirical relationships to predict the maximum scour depth and length as well as the maximum dune height based on a novel, equivalent Froude number, which accounts for the effects of channel curvature and structure position. Moreover, the various resulting scour morphology types were classified, and conditions of their existence were determined depending on the abovementioned Froude number and other key hydraulic parameters. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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25 pages, 3088 KB  
Review
MSFD In-Depth Knowledge of the Marine Environment as the Stepping Stone to Perform Marine Spatial Planning in Greece
by Theodora Paramana, Aikaterini Karditsa, Niki Milatou, Stelios Petrakis, Persefoni Megalofonou, Serafim Poulos and Manos Dassenakis
Water 2021, 13(15), 2084; https://doi.org/10.3390/w13152084 - 30 Jul 2021
Cited by 15 | Viewed by 6205
Abstract
The multiple anthropogenic activities taking place in the marine environment increase and create a high demand for maritime space. The pressures generated thereof on coastal and marine resources require an integrated planning and management approach. The MSPD (2014/89/EU) forms the legislative framework to [...] Read more.
The multiple anthropogenic activities taking place in the marine environment increase and create a high demand for maritime space. The pressures generated thereof on coastal and marine resources require an integrated planning and management approach. The MSPD (2014/89/EU) forms the legislative framework to regulate maritime activities and ensure a sustainable use of the marine environment. Based on the MSFD (2008/56/EC), the present study provides an overview of the state of the marine environment in Greece and the existing pressures while examining the potential contribution of MSFD knowledge to the MSPD implementation, identifying possible knowledge gaps for the subsequent MSP process phases. It is supported that the MSFD constitutes the best available scientific knowledge about the ecosystem and its dynamics, and provides an open access database which should be optimally used in the MSP process. The MSFD data provided concerning Greece can support the implementation of the MSP process, as the MSFD qualitative descriptors of state and pressures feed MSP sectors with environmental data essential for the MSP application, and weigh the intensity of each descriptor contribution to this interrelationship. Considering MSPD requires the adoption of an ecosystem-based approach, it can only attain its goals based on MSFD input and aspirations. Full article
(This article belongs to the Special Issue Coastal and Continental Shelf Dynamics in a Changing Climate)
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18 pages, 9733 KB  
Article
Spatiotemporal Hotspots and Decadal Evolution of Extreme Rainfall-Induced Landslides: Case Studies in Southern Taiwan
by Chunhung Wu and Chengyi Lin
Water 2021, 13(15), 2090; https://doi.org/10.3390/w13152090 - 30 Jul 2021
Cited by 12 | Viewed by 3406
Abstract
The 2009 Typhoon Morakot triggered numerous landslides in southern Taiwan, and the landslide ratios in the Ailiao and Tamali river watershed were 7.6% and 10.7%, respectively. The sediment yields from the numerous landslides that were deposited in the gullies and narrow reaches upstream [...] Read more.
The 2009 Typhoon Morakot triggered numerous landslides in southern Taiwan, and the landslide ratios in the Ailiao and Tamali river watershed were 7.6% and 10.7%, respectively. The sediment yields from the numerous landslides that were deposited in the gullies and narrow reaches upstream of Ailiao and Tamali river watersheds dominated the landslide recovery and evolution from 2010 to 2015. Rainfall records and annual landslide inventories from 2005 to 2015 were used to analyze the landslide evolution and identify the landslide hotspots. The landslide recovery time in the Ailiao and Tamali river watershed after 2009 Typhoon Morakot was estimated as 5 years after 2009 Typhoon Morakot. The landslide was easily induced, enlarged, or difficult to recover during the oscillating period, particularly in the sub-watersheds, with a landslide ratio > 4.4%. The return period threshold of rainfall-induced landslides during the landslide recovery period was <2 years, and the landslide types of the new or enlarged landslide were the bank-erosion landslide, headwater landslide, and the reoccurrence of old landslide. The landslide hotspot areas in the Ailiao and Tamali river watershed were 2.67–2.88 times larger after the 2009 Typhoon Morakot using the emerging hot spot analysis, and most of the new or enlarged landslide cases were identified into the oscillating or sporadic or consecutive landslide hotspots. The results can contribute to developing strategies of watershed management in watersheds with a dense landslide. Full article
(This article belongs to the Special Issue Soil–Water Conservation, Erosion, and Landslide)
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28 pages, 8150 KB  
Article
Impacts of Irrigation Managements on Soil CO2 Emission and Soil CH4 Uptake of Winter Wheat Field in the North China Plain
by Faisal Mehmood, Guangshuai Wang, Yang Gao, Yueping Liang, Muhammad Zain, Shafeeq Ur Rahman and Aiwang Duan
Water 2021, 13(15), 2052; https://doi.org/10.3390/w13152052 - 28 Jul 2021
Cited by 29 | Viewed by 4188
Abstract
The North China Plain is an important irrigated agricultural area in China. However, the effects of irrigation management on carbon emission are not well documented in this region. Due to the uneven seasonal distribution of rainfall, irrigation is mainly concentrated in the winter [...] Read more.
The North China Plain is an important irrigated agricultural area in China. However, the effects of irrigation management on carbon emission are not well documented in this region. Due to the uneven seasonal distribution of rainfall, irrigation is mainly concentrated in the winter wheat growing season in the North China Plain. In this study, we estimated CO2 emission and soil CH4 uptake from winter wheat fields with different irrigation methods and scheduling treatments using the static chamber-gas chromatography method from April to May 2017 and 2018. Treatments included three irrigation methods (surface drip, sprinkler, and border) and three irrigation scheduling levels that initiated as soon as the soil moisture drained to 50%, 60%, and 70% of the field capacity for a 0–100 cm soil profile were tested. The results showed that both the irrigation methods and scheduling significantly influenced (p < 0.05) the cumulative CO2 and CH4 emission, grain yield, global warming potential (GWP), GWP Intensity (GWPI), GWPI per unit irrigation applied, and water use efficiency (WUE). Compared to 60% and 70% FC, 50% FC irrigation scheduling de-creased accumulated CH4 uptake 26.8–30.3% and 17.8–25.4%, and reduced accumulated CO2 emissions 7.0–15.3% and 12.6–19.4%, respectively. Conversely, 50% FC reduced GWP 6.5–13.3% and 12.5–19.4% and lower grain yield 10.4–19.7% and 8.5–16.6% compared to 60% and 70% FC irrigation scheduling in 2017 and 2018, respectively. Compared to sprinkler irrigation and border irrigation, drip irrigation at 60% FC increased the accumulated CH4 uptake 11.3–12.1% and 1.9–5.5%, while reduced the accumulated CO2 emissions from 7.5–8.8% and 10.1–12.1% in 2017 and 2018, respectively. Moreover, drip irrigation at 60% FC increased grain yield 5.2–7.5% and 6.3–6.8%, WUE 0.9–5.4% and 5.7–7.4%, and lowered GWP 8.0–9.8% and 10.1–12.0% compared to sprinkler and border irrigation in 2017 and 2018, respectively. The interaction of irrigation scheduling and irrigation methods significantly impacted accumulated CH4 uptake, cumulative CO2 amount, and GWP in 2018 only while grain yield and WUE in the entire study. Overall, drip irrigation at 60% FC is the optimal choice in terms of higher grain yield, WUE, and mitigating GWP and GWPI from winter wheat fields in North China Plain. Full article
(This article belongs to the Special Issue Measures on Irrigation and Agronomy to Improve Crop Water Use Efficiency)
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25 pages, 7787 KB  
Article
A Spatially Explicit Crop Yield Model to Simulate Agricultural Productivity for Past Societies under Changing Environmental Conditions
by Maarten Van Loo and Gert Verstraeten
Water 2021, 13(15), 2023; https://doi.org/10.3390/w13152023 - 24 Jul 2021
Cited by 8 | Viewed by 3778
Abstract
Most contemporary crop yield models focus on a small time window, operate on a plot location, or do not include the effects of the changing environment, which makes it difficult to use these models to assess the agricultural sustainability for past societies. In [...] Read more.
Most contemporary crop yield models focus on a small time window, operate on a plot location, or do not include the effects of the changing environment, which makes it difficult to use these models to assess the agricultural sustainability for past societies. In this study, adaptions were made to the agronomic AquaCrop model. This adapted model was ran to cover the last 4000 years to simulate the impact of climate and land cover changes, as well as soil dynamics, on the productivity of winter wheat crops for a Mediterranean mountain environment in SW Turkey. AquaCrop has been made spatially explicit, which allows hydrological interactions between different landscape positions, whilst computational time is kept limited by implementing parallelisation schemes on a supercomputer. The adapted model was calibrated and validated using crop and soil information sampled during the 2015 and 2016 harvest periods. Simulated crop yields for the last 4000 years show the strong control of precipitation, while changes in soil thickness following erosion, and to lesser extent re-infiltration of runoff along a slope catena also have a significant impact on crop yield. The latter is especially important in the valleys, where soil and water accumulate. The model results also show that water export to the central valley strongly increased (up to four times) following deforestation and the resulting soil erosion on the hillslopes, turning it into a marsh and rendering it unsuitable for crop cultivation. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
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22 pages, 2086 KB  
Article
Causal Relations of Upscaled Urban Aquaponics and the Food-Water-Energy Nexus—A Berlin Case Study
by Gösta F. M. Baganz, Manfred Schrenk, Oliver Körner, Daniela Baganz, Karel J. Keesman, Simon Goddek, Zorina Siscan, Elias Baganz, Alexandra Doernberg, Hendrik Monsees, Thomas Nehls, Werner Kloas and Frank Lohrberg
Water 2021, 13(15), 2029; https://doi.org/10.3390/w13152029 - 24 Jul 2021
Cited by 18 | Viewed by 8519
Abstract
Aquaponics, the water-reusing production of fish and crops, is taken as an example to investigate the consequences of upscaling a nature-based solution in a circular city. We developed an upscaled-aquaponic scenario for the German metropolis of Berlin, analysed the impacts, and studied the [...] Read more.
Aquaponics, the water-reusing production of fish and crops, is taken as an example to investigate the consequences of upscaling a nature-based solution in a circular city. We developed an upscaled-aquaponic scenario for the German metropolis of Berlin, analysed the impacts, and studied the system dynamics. To meet the annual fish, tomato, and lettuce demand of Berlin’s 3.77 million residents would require approximately 370 aquaponic facilities covering a total area of 224 hectares and the use of different combinations of fish and crops: catfish/tomato (56%), catfish/lettuce (13%), and tilapia/tomato (31%). As a predominant effect, in terms of water, aquaponic production would save about 2.0 million m3 of water compared to the baseline. On the supply-side, we identified significant causal link chains concerning the Food-Water-Energy nexus at the aquaponic facility level as well as causal relations of a production relocation to Berlin. On the demand-side, a ‘freshwater pescatarian diet’ is discussed. The new and comprehensive findings at different system levels require further investigations on this topic. Upscaled aquaponics can produce a relevant contribution to Berlin’s sustainability and to implement it, research is needed to find suitable sites for local aquaponics in Berlin, possibly inside buildings, on urban roofscape, or in peri-urban areas. Full article
(This article belongs to the Special Issue Water and Circular Cities)
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20 pages, 1537 KB  
Article
Towards Regional Scale Stormwater Flood Management Strategies through Rapid Preliminary Intervention Screening
by James L. Webber, Mariano Balbi, David Lallemant, Michael J. Gibson, Guangtao Fu, David Butler and Perrine Hamel
Water 2021, 13(15), 2027; https://doi.org/10.3390/w13152027 - 24 Jul 2021
Cited by 9 | Viewed by 5632
Abstract
This paper presents the advantages and opportunities for rapid preliminary intervention screening to enhance inclusion of green infrastructures in regional scale stormwater management. Stormwater flooding is widely recognised as a significant and worsening natural hazard across the globe; however, current management approaches aimed [...] Read more.
This paper presents the advantages and opportunities for rapid preliminary intervention screening to enhance inclusion of green infrastructures in regional scale stormwater management. Stormwater flooding is widely recognised as a significant and worsening natural hazard across the globe; however, current management approaches aimed at the site scale do not adequately explore opportunities for integrated management at the regional scale at which decisions are made. This research addresses this gap through supporting the development of stormwater management strategies, including green infrastructure, at a regional scale. This is achieved through upscaling a modelling approach using a spatially explicit inundation model (CADDIES) coupled with an economic model of inundation loss (OpenProFIA) to support widescale evaluation of green infrastructure during the informative early-stage development of stormwater management strategies. This novel regional scale approach is demonstrated across a case study of the San Francisco Bay Area, spanning 8300 sq km. The main opportunity from this regional approach is to identify spatial and temporal trends which are used to inform regional planning and direct future detailed modelling efforts. The study highlights several limitations of the new method, suggesting it should be applied as part of a suite of landscape management approaches; however, highlights that it has the potential to complement existing stormwater management toolkits. Full article
(This article belongs to the Special Issue The Scale Effects of Green Infrastructures on Urban Stormwater Runoff)
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14 pages, 3552 KB  
Article
Hybrid Scour Depth Prediction Equations for Reliable Design of Bridge Piers
by Hossein Hamidifar, Faezeh Zanganeh-Inaloo and Iacopo Carnacina
Water 2021, 13(15), 2019; https://doi.org/10.3390/w13152019 - 23 Jul 2021
Cited by 27 | Viewed by 4409
Abstract
Numerous models have been proposed in the past to predict the maximum scour depth around bridge piers. These studies have all focused on the different parameters that could affect the maximum scour depth and the model accuracy. One of the main parameters individuated [...] Read more.
Numerous models have been proposed in the past to predict the maximum scour depth around bridge piers. These studies have all focused on the different parameters that could affect the maximum scour depth and the model accuracy. One of the main parameters individuated is the critical velocity of the approaching flow. The present study aimed at investigating the effect of different equations to determine the critical flow velocity on the accuracy of models for estimating the maximum scour depth around bridge piers. Here, 10 scour depth estimation equations, which include the critical flow velocity as one of the influencing parameters, and 8 critical velocity estimation equations were examined, for a total combination of 80 hybrid models. In addition, a sensitivity analysis of the selected scour depth equations to the critical velocity was investigated. The results of the selected models were compared with experimental data, and the best hybrid models were identified using statistical indicators. The accuracy of the best models, including YJAF-VRAD, YJAF-VARN, and YJAI-VRAD models, was also evaluated using field data available in the literature. Finally, correction factors were implied to the selected models to increase their accuracy in predicting the maximum scour depth. Full article
(This article belongs to the Special Issue Local Erosion of Hydraulic Structures and Flood Protection)
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22 pages, 9841 KB  
Article
Nature-Based Coastal Protection by Large Woody Debris as Compared to Seawalls: A Physical Model Study of Beach Morphology and Wave Reflection
by Pauline Falkenrich, Jessica Wilson, Ioan Nistor, Nils Goseberg, Andrew Cornett and Abdolmajid Mohammadian
Water 2021, 13(15), 2020; https://doi.org/10.3390/w13152020 - 23 Jul 2021
Cited by 9 | Viewed by 4619
Abstract
Anchored Large Woody Debris (LWD) is increasingly being used as one of several nature-based coastal protection strategies along the north-western coasts of Canada and the US. As an alternative to conventional hard armoring (e.g., seawalls), its usage is widely considered to be less [...] Read more.
Anchored Large Woody Debris (LWD) is increasingly being used as one of several nature-based coastal protection strategies along the north-western coasts of Canada and the US. As an alternative to conventional hard armoring (e.g., seawalls), its usage is widely considered to be less harmful to the coastal ecosystem while maintaining the ability to protect the beaches against wave attack and erosion. The effects of seawalls on beaches have been extensively studied; however, the performance and efficacy of LWD and its potential as a suitable alternative to seawalls (and other shoreline protection structures) are still understudied in current research. This paper presents and compares the effects of a conventional vertical seawall with two different LWD structures on beach morphology and wave reflection through large-scale physical modeling in a wave flume at a 1:5 scale. An assessment of techniques used to measure beach morphology and an assessment of model effects were included in the study. It was found that the wave reflection could be reduced by using a single log instead of a wall structure, while changes in the beach morphology response largely depended on the type of the LWD structure. A stacked log wall showed near-identical behavior as a conventional seawall. Visible model effects from the experiments, including the effect of the flume sidewalls on the beach morphology, were quantified and analyzed to inform future research. Full article
(This article belongs to the Special Issue Advances in Coastal and Ocean Engineering)
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19 pages, 2567 KB  
Article
Integrated Operation of Multi-Reservoir and Many-Objective System Using Fuzzified Hedging Rule and Strength Pareto Evolutionary Optimization Algorithm (SPEA2)
by Alireza B. Dariane, Mohammad M. Sabokdast, Farzane Karami, Roza Asadi, Kumaraswamy Ponnambalam and Seyed Jamshid Mousavi
Water 2021, 13(15), 1995; https://doi.org/10.3390/w13151995 - 21 Jul 2021
Cited by 6 | Viewed by 3160
Abstract
In this paper, a many-objective optimization algorithm was developed using SPEA2 for a system of four reservoirs in the Karun basin, including hydropower, municipal and industrial, agricultural, and environmental objectives. For this purpose, using 53 years of available data, hedging rules were developed [...] Read more.
In this paper, a many-objective optimization algorithm was developed using SPEA2 for a system of four reservoirs in the Karun basin, including hydropower, municipal and industrial, agricultural, and environmental objectives. For this purpose, using 53 years of available data, hedging rules were developed in two modes: with and without applying fuzzy logic. SPEA2 was used to optimize hedging coefficients using the first 43 years of data and the last 10 years of data were used to test the optimized rule curves. The results were compared with those of non-hedging methods, including the standard operating procedures (SOP) and water evaluation and planning (WEAP) model. The results indicate that the combination of fuzzy logic and hedging rules in a many-objectives system is more efficient than the discrete hedging rule alone. For instance, the reliability of the hydropower requirement in the fuzzified discrete hedging method in a drought scenario was found to be 0.68, which is substantially higher than the 0.52 from the discrete hedging method. Moreover, reduction of the maximum monthly shortage is another advantage of this rule. Fuzzy logic reduced 118 million cubic meters (MCM) of deficit in the Karun-3 reservoir alone. Moreover, as expected, the non-hedging SOP and WEAP model produced higher reliabilities, lower average storages, and less water losses through spills. Full article
(This article belongs to the Special Issue Planning and Operations of Adaptive Multi-Objective Multi-Reservoir Systems)
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18 pages, 2687 KB  
Article
Assessing Soil Loss by Water Erosion in a Typical Mediterranean Ecosystem of Northern Greece under Current and Future Rainfall Erosivity
by Stefanos Stefanidis, Vasileios Alexandridis, Chrysoula Chatzichristaki and Panagiotis Stefanidis
Water 2021, 13(15), 2002; https://doi.org/10.3390/w13152002 - 21 Jul 2021
Cited by 30 | Viewed by 4948
Abstract
Soil is a non-renewable resource essential for life existence. During the last decades it has been threatened by accelerating erosion with negative consequences for the environment and the economy. The aim of the current study was to assess soil loss changes in a [...] Read more.
Soil is a non-renewable resource essential for life existence. During the last decades it has been threatened by accelerating erosion with negative consequences for the environment and the economy. The aim of the current study was to assess soil loss changes in a typical Mediterranean ecosystem of Northern Greece, under climate change. To this end, freely available geospatial data was collected and processed using open-source software package. The widespread RUSLE empirical erosion model was applied to estimate soil loss. Current and future rainfall erosivity were derived from a national scale study considering average weather conditions and RCMs outputs for the medium Representative Concentration Pathway scenario (RCP4.5). Results showed that average rainfall erosivity (R-Factor) was 508.85 MJ mm ha h−1 y−1 while the K-factor ranged from 0.0008 to 0.05 t ha h ha−1 MJ−1 mm−1 and LS-factor reached 60.51. Respectively, C-factor ranged from 0.01 to 0.91 and P-factor ranged from 0.42 to 1. The estimated potential soil loss rates will remain stable for the near future period (2021–2050), while an increase of approximately 9% is expected by the end of the 21th century (2071–2100). The results suggest that appropriate erosion mitigation strategies should be applied to reduce erosion risk. Subsequently, appropriate mitigation measures per Land Use/Land Cover (LULC) categories are proposed. It is worth noting that the proposed methodology has a high degree of transferability as it is based on open-source data. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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24 pages, 35891 KB  
Article
A Continental Assessment of Reservoir Storage and Water Availability in South America
by Bolivar Paredes-Beltran, Alvaro Sordo-Ward, B. de-Lama and Luis Garrote
Water 2021, 13(14), 1992; https://doi.org/10.3390/w13141992 - 20 Jul 2021
Cited by 10 | Viewed by 5021
Abstract
This study presents the first continental assessment of water storage and its influence on the availability of water of the river systems of South America. Although hydraulic infrastructure has the potential to cause several impacts on river systems and the environment, their relevance [...] Read more.
This study presents the first continental assessment of water storage and its influence on the availability of water of the river systems of South America. Although hydraulic infrastructure has the potential to cause several impacts on river systems and the environment, their relevance in water resources systems is irrefutable. The human services that dams and reservoirs provide to society, e.g., hydroelectricity, water supply, irrigation, or flood control, are vital services that society requires to develop. Despite this fact, the interactions of dams and reservoirs in the river systems of South America have not been explored from a hydrological perspective. In this study, we present the first assessment of the potential effects of water storage at a basin scale in South America. For this purpose, first we present an analysis of the current conditions and the influence of water storage in the basins of the continent. Then, we estimate the potential water availability of each basin, to evaluate the role of water storage in the availability of water in the continent. Our findings indicate that the ‘Colorado’ and ‘Negro’ basins in Argentina are the most influenced by water storage in the continent. Moreover, our results suggest that reservoirs improve the potential water availability capacity, particularly in the southern basins of the continent. With this study, we expect to provide helpful insights about the current interactions of reservoirs with the river systems of the continent. Full article
(This article belongs to the Special Issue Water Resources Systems in a Changing World: Planning and Adaptation)
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16 pages, 3916 KB  
Article
Retrieving Surface Soil Moisture over Wheat-Covered Areas Using Data from Sentinel-1 and Sentinel-2
by Yan Li, Chengcai Zhang and Weidong Heng
Water 2021, 13(14), 1981; https://doi.org/10.3390/w13141981 - 19 Jul 2021
Cited by 11 | Viewed by 3352
Abstract
Surface soil moisture (SSM) is a major factor that affects crop growth. Combined microwave and optical data have been widely used to improve the accuracy of SSM retrievals. However, the influence of vegetation indices derived from the red-edge spectral bands of multi-spectral optical [...] Read more.
Surface soil moisture (SSM) is a major factor that affects crop growth. Combined microwave and optical data have been widely used to improve the accuracy of SSM retrievals. However, the influence of vegetation indices derived from the red-edge spectral bands of multi-spectral optical data on retrieval accuracy has not been sufficiently analyzed. In this study, we retrieved soil moisture from wheat-covered surfaces using Sentinel-1/2 data. First, a modified water cloud model (WCM) was proposed to remove the influence of vegetation from the backscattering coefficient of the radar data. The vegetation fraction (FV) was then introduced in this WCM, and the vegetation water content (VWC) was calculated using a multiple linear regression model. Subsequently, the support vector regression technique was used to retrieve the SSM. This approach was validated using in situ measurements of wheat fields in Hebi, located in northern Henan Province, China. The key findings of this study are: (1) Based on vegetation indices obtained from Sentinel-2 data, the proposed VWC estimation model effectively eliminated the influence of vegetation; (2) Compared with vertical transmit and horizontal receive (VH) polarization, vertical transmit and vertical receive (VV) polarization was better for detecting changes in SSM key phenological phases of wheat; (3) The validated model indicates that the proposed approach successfully retrieved SSM in the study area using Sentinel-1 and Sentinel-2 data. Full article
(This article belongs to the Section Hydrology)
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19 pages, 1926 KB  
Article
LCA-Based Environmental Performance of Olive Cultivation in Northwestern Greece: From Rainfed to Irrigated through Conventional and Smart Crop Management Practices
by Konstantina Fotia, Andi Mehmeti, Ioannis Tsirogiannis, George Nanos, Andreas P. Mamolos, Nikolaos Malamos, Pantelis Barouchas and Mladen Todorovic
Water 2021, 13(14), 1954; https://doi.org/10.3390/w13141954 - 16 Jul 2021
Cited by 34 | Viewed by 6541
Abstract
Olive cultivation is expanding rapidly in the northwestern part of Greece, under both rainfed and irrigated practices. Irrigation can result in larger yields and economic returns, but trade-offs in the water–energy–pollution nexus remain a controversial and challenging issue. This study presents an environmental [...] Read more.
Olive cultivation is expanding rapidly in the northwestern part of Greece, under both rainfed and irrigated practices. Irrigation can result in larger yields and economic returns, but trade-offs in the water–energy–pollution nexus remain a controversial and challenging issue. This study presents an environmental Life Cycle Assessment (LCA) of Greek olive orchard systems in the plain of Arta (Epirus), comparing rainfed (baseline), Decision Support System (DSS)-based (smart) irrigation practices and farmer experience-based (conventional) irrigation practices. The contributions in this paper are, first, to provide a first quantitative indication of the environmental performance of Greek olive growing systems under different management strategies, and second, to detail the advantages that can be achieved using smart irrigation in olive cultivation in the Greek and Mediterranean contexts. Eighteen midpoints (e.g., climate change, water scarcity, acidification, freshwater eutrophication, etc.), two endpoints (damages on human health and ecosystem quality), and a single score (overall environmental impact) were quantified using the IMPACT World+ life cycle impact assessment method. The LCA model was set up using the OpenLCA software v1.10.3. The functional units were 1 ton of product (mass-based) and 1 ha of cultivated area (area-based) on a cradle-to-farm gate perspective. Irrigated systems had the lowest impacts per mass unit due to higher yields, but showed the highest impacts per cultivated area. The DSS-based irrigation management could reduce water and energy use by 42.1% compared to conventional practices. This is translated into a reduction of 5.3% per 1 ton and 10.4% per 1 ha of the total environmental impact. A sensitivity analysis of impact assessment models demonstrated that the benefits could be up to 18% for 1 ton of product or 22.6% for 1 ha of cultivated land. These results outline that DSS-based irrigation is a promising option to support less resource-intensive and sustainable intensification of irrigated agriculture systems in the plain of Arta. Full article
(This article belongs to the Special Issue Climate Smart Irrigation Management for Sustainable Agricultural Cultivation)
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21 pages, 7655 KB  
Article
Visible-Light-Driven Bio-Templated Magnetic Copper Oxide Composite for Heterogeneous Photo-Fenton Degradation of Tetracycline
by Olushola Adewole Alani, Hadiza Abdullahi Ari, Susanna Olushola Alani, Nnanake-Abasi O. Offiong and Wei Feng
Water 2021, 13(14), 1918; https://doi.org/10.3390/w13141918 - 12 Jul 2021
Cited by 18 | Viewed by 4498
Abstract
The development of a visible-light-driven, reusable, and long-lasting catalyst for the heterogeneous photo-Fenton process is critical for practical application in the treatment of contaminated water. This study focuses on synthesizing a visible-light-driven heterogenous bio-templated magnetic copper oxide composite (Fe3O4/CuO/C) [...] Read more.
The development of a visible-light-driven, reusable, and long-lasting catalyst for the heterogeneous photo-Fenton process is critical for practical application in the treatment of contaminated water. This study focuses on synthesizing a visible-light-driven heterogenous bio-templated magnetic copper oxide composite (Fe3O4/CuO/C) by a two-step process of bio-templating and hydrothermal processes. The prepared composite was characterized by field emission-scanning electron microscope (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrical impedance spectroscopy (EIS), and vibrating sample magnetometer (VSM). The results reveal that the prepared composite retains the template’s (corn stalk’s) original porous morphology, and a substantial amount of CuO and Fe3O4 particles are loaded onto the surface of the template. The prepared Fe3O4/CuO/C composite was employed as a catalyst for heterogeneous photo-Fenton degradation of tetracycline (TC) irradiated by visible light. The prepared Fe3O4/CuO/C catalyst has high efficiency towards TC degradation within 60 min across a wide pH range irradiated by visible light, which is attributed to its readily available interfacial boundaries, which significantly improves the movement of photoexcited electrons across various components of the prepared composite. The influence of other parameters such as initial H2O2 concentration, initial concentration of TC, and catalyst dosages was also studied. In addition to high efficiency, the prepared catalyst’s performance was sustained after five cycles, and its recovery is aided by the use of an external magnetic field. This research paper highlights the development of a heterogeneous catalyst for the elimination of refractory organic compounds in wastewater. Full article
(This article belongs to the Special Issue Removal of Emerging Contaminants from Waters Using Nanotechnology)
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15 pages, 3264 KB  
Article
Anthropogenic Organic Pollutants in Groundwater Increase Releases of Fe and Mn from Aquifer Sediments: Impacts of Pollution Degree, Mineral Content, and pH
by Yuanzheng Zhai, Yifan Han, Xuelian Xia, Xindai Li, Hong Lu, Yanguo Teng and Jinsheng Wang
Water 2021, 13(14), 1920; https://doi.org/10.3390/w13141920 - 12 Jul 2021
Cited by 34 | Viewed by 5327
Abstract
In many aquifers around the world, there exists the issue of abnormal concentrations of Fe and Mn in groundwater. Although it has been recognized that the main source of this issue is the release of Fe and Mn from aquifer sediments into groundwater [...] Read more.
In many aquifers around the world, there exists the issue of abnormal concentrations of Fe and Mn in groundwater. Although it has been recognized that the main source of this issue is the release of Fe and Mn from aquifer sediments into groundwater under natural environmental conditions, there lacks enough reliable scientific evidence to illustrate whether the pollutants imported from anthropogenic activities, such as organics, can increase this natural release. On the basis of time series analysis and comparative analysis, the existence of an increasing effect was verified through laboratorial leaching test, and the impacts of aquatic chemical environment conditions, such as pH, on the effect were also identified. The results showed that the increase of organics in groundwater made the release of Fe and Mn more thorough, which was favorable for the increase of groundwater concentrations of Fe and Mn. The higher the contents of Fe- and Mn-bearing minerals in aquifer sediments, the higher the concentrations of Fe and Mn in groundwater after the release reaches kinetic equilibrium. Lower pH can make the leaching more thorough, but the neutral environment also increases the amount of Mn. It can be deduced that the pollutants such as organics imported by anthropogenic activities can indeed increase the releases of Fe and Mn from aquifer sediments into groundwater, thus worsening the issue of groundwater Fe and Mn pollution. The findings provide a deeper insight into the geochemical effects of Fe and Mn in the natural environment, especially in the groundwater system. Full article
(This article belongs to the Special Issue Impact of Human Activities on Groundwater Quality)
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25 pages, 4894 KB  
Article
Leakage Management and Pipe System Efficiency. Its Influence in the Improvement of the Efficiency Indexes
by Carlos Andrés Macías Ávila, Francisco-Javier Sánchez-Romero, P. Amparo López-Jiménez and Modesto Pérez-Sánchez
Water 2021, 13(14), 1909; https://doi.org/10.3390/w13141909 - 9 Jul 2021
Cited by 31 | Viewed by 10964
Abstract
Water is one of the most valuable resources for humans. Worldwide, leakage levels in water distribution systems oscillate between 10% and 55%. This causes the need for constant repairs, economic losses, and risk to the health of users due to possible pathogenic intrusion. [...] Read more.
Water is one of the most valuable resources for humans. Worldwide, leakage levels in water distribution systems oscillate between 10% and 55%. This causes the need for constant repairs, economic losses, and risk to the health of users due to possible pathogenic intrusion. There are different methods for estimating the level of leakage in a network, depending on parameters such as service pressure, orifice size, age and pipe material. Sixty-two water distribution networks were analyzed to determine the leakage method used, the calibration method, and the percentage of existing leaks. Different efficiency indicators were proposed and evaluated using this database. Several cases of installation of pumps working as turbines (PATs) in water distribution networks were analyzed in which the use of these recovery systems caused a pressure drop, reducing the level of leaks and recovering energy. Full article
(This article belongs to the Special Issue Integrated Management of Water Systems: Energy Recovery, Pressure Control, and Smart Solutions)
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16 pages, 4416 KB  
Article
Analysis of the Water–Energy Nexus of Treated Wastewater Reuse at a Municipal Scale
by Cristina Santos, Francisco Taveira-Pinto, David Pereira and Cristina Matos
Water 2021, 13(14), 1911; https://doi.org/10.3390/w13141911 - 9 Jul 2021
Cited by 7 | Viewed by 3898
Abstract
Treated wastewater has the potential to be a feasible alternative to supply non-potable uses and avoid water scarcity in urban areas, but it is important to understand and compare the associated energy consumption and CO2 emissions. This study presents a comparative analysis [...] Read more.
Treated wastewater has the potential to be a feasible alternative to supply non-potable uses and avoid water scarcity in urban areas, but it is important to understand and compare the associated energy consumption and CO2 emissions. This study presents a comparative analysis of the water–energy nexus associated with the traditional water supply and to the alternative reuse of treated wastewater, both for non-potable purposes. A case study of a Portuguese municipality was considered, regarding golf course irrigation and municipal gardens irrigation. A balance between production and demand was established, and the energy consumption and CO2 emissions were calculated considering the supply with drinking water and with treated wastewater. Three scenarios were defined to analyze the water–energy nexus for different configurations of the potential end-uses: (1) golf course supply, (2) municipal irrigation supply and (3) simultaneous supply to the golf course and to municipal irrigation. A quality analysis was also carried out by comparing the records from discharged wastewater quality parameters with the limits presented in the legislation for each proposed non-potable use. The results show that all scenarios present significant annual savings from using treated wastewater instead of drinking water from the public network, especially scenarios 1 and 3, that consider the golf course irrigation (water costs decrease by about 60,000.00 EUR/year). Regarding the water–energy nexus, this study reveals that treated wastewater spends less energy on its production and supply and produces fewer CO2 emissions. The energy savings can reach an average value of about kWh/year, with 5300 fewer kg of CO2 emitted in the best scenario. Full article
(This article belongs to the Special Issue Urban Wastewater Reuse – Challenges, Risks and Opportunities)
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22 pages, 5902 KB  
Article
Comparison of In-Situ Chlorophyll-a Time Series and Sentinel-3 Ocean and Land Color Instrument Data in Slovenian National Waters (Gulf of Trieste, Adriatic Sea)
by El Khalil Cherif, Patricija Mozetič, Janja Francé, Vesna Flander-Putrle, Jana Faganeli-Pucer and Martin Vodopivec
Water 2021, 13(14), 1903; https://doi.org/10.3390/w13141903 - 9 Jul 2021
Cited by 18 | Viewed by 5269
Abstract
While satellite remote sensing of ocean color is a viable tool for estimating large-scale patterns of chlorophyll-a (Chl-a) and global ocean primary production, its application in coastal waters is limited by the complex optical properties. An exploratory study was conducted in [...] Read more.
While satellite remote sensing of ocean color is a viable tool for estimating large-scale patterns of chlorophyll-a (Chl-a) and global ocean primary production, its application in coastal waters is limited by the complex optical properties. An exploratory study was conducted in the Gulf of Trieste (Adriatic Sea) to assess the usefulness of Sentinel-3 satellite data in the Slovenian national waters. OLCI (Ocean and Land Colour Instrument) Chl-a level 2 products (OC4Me and NN) were compared to monthly Chl-a in-situ measurements at fixed sites from 2017 to 2019. In addition, eight other methods for estimating Chl-a concentration based on reflectance in different spectral bands were tested (OC3M, OC4E, MedOC4, ADOC4, AD4, 3B-OLCI, 2B-OLCI and G2B). For some of these methods, calibration was performed on in-situ data to achieve a better agreement. Finally, L1-regularized regression and random forest were trained on the available dataset to test the capabilities of the machine learning approach. The results show rather poor performance of the two originally available products. The same is true for the other eight methods and the fits to the measured values also show only marginal improvement. The best results are obtained with the blue-green methods (OC3, OC4 and AD4), especially the AD4SI (a designated fit of AD4) with R = 0.56 and RMSE = 0.4 mg/m³, while the near infrared (NIR) methods show underwhelming performance. The machine learning approach can only explain 30% of the variability and the RMSE is of the same order as for the blue-green methods. We conclude that due to the low Chl-a concentration and the moderate turbidity of the seawater, the reflectance provided by the Sentinel-3 OLCI spectrometer carries little information about Chl-a in the Slovenian national waters within the Gulf of Trieste and is therefore of limited use for our purposes. This requires that we continue to improve satellite products for use in those marine waters that have not yet proven suitable. In this way, satellite data could be effectively integrated into a comprehensive network that would allow a reliable assessment of ecological status, taking into account environmental regulations. Full article
(This article belongs to the Special Issue Phytoplankton Ecology and Physiology of Coastal Seas)
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