Water

20 pages, 6256 KiB

Open AccessArticle

Pressures and Challenges in Use and Management of Water in Rural Schools Affected by Drought in Valparaíso, Chile

by Nina Hormazabal, Paula Guerra-Pinto, Loreine Candia, María Córdova, María Ortiz and Javiera Silva

Water 2025, 17(7), 952; https://doi.org/10.3390/w17070952 (registering DOI) - 25 Mar 2025

Abstract

Over 1350 Chilean rural schools are experiencing a lack of potable water, and 40.4% of them lack formal access to drinking water and have to resort to various alternative sources of supply, with 43% relying on wells or waterwheels, 32% using water trucks, [...] Read more.

Over 1350 Chilean rural schools are experiencing a lack of potable water, and 40.4% of them lack formal access to drinking water and have to resort to various alternative sources of supply, with 43% relying on wells or waterwheels, 32% using water trucks, and 26% relying on rivers, springs, or streams. Due to the extreme situation, most inhabitants of affected rural areas count on different means of water recycling, mainly reused from irrigation, without control or management of water quality. For this study, Los Bellotos de la Vega Elementary, a rural school, became a case study as proposed by the Municipality of Olmué. The educational program focuses on crops and plantations based on rural agricultural practices, which are irrigated by a water recycling system. Through microbiological water analysis, olfactory air quality testing, surveys, and photovoice methods, we identified serious problems with the implementation and management of the water recycling system, including a lack of resources and maintenance, which could endanger the health of the members of the community. An analysis of the treatment plant’s water revealed that the recycled water did not meet quality standards, and the water supplied by water trucks was at the limits of the standards. It was also found that all the families related to the school children recycle water in their homes without any control over the quality of the water they reuse. However, a positive aspect revealed by this study is the elevated level of awareness about water conservation, habits of use, consumption, rationing, and reuse, as well as knowledge of appropriate vegetation, and they are already part of daily life. Full article

(This article belongs to the Special Issue Sustainable Development of Water, Energy and Environment Systems (SDEWES 2024))

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19 pages, 9421 KiB

Open AccessArticle

Risk Analysis of Urban Drainage System Siltation Based on Complex Networks

by Jinping Zhang, Yao Wang, Lixin Zhang, Xi Zhang and Yirong Yang

Water 2025, 17(7), 951; https://doi.org/10.3390/w17070951 (registering DOI) - 25 Mar 2025

Abstract

The performance of urban drainage systems can be significantly compromised by siltation in pipeline networks. This study focuses on the drainage network of central Zhengzhou, analyzing operational risks under current siltation conditions. Using complex network theory, the study examines the structural characteristics and [...] Read more.

The performance of urban drainage systems can be significantly compromised by siltation in pipeline networks. This study focuses on the drainage network of central Zhengzhou, analyzing operational risks under current siltation conditions. Using complex network theory, the study examines the structural characteristics and propagation mechanisms of the siltation propagation chain, quantifying node risks through indicators such as pipeline risk factors and degree centrality. Edge vulnerability is incorporated to evaluate the risk values of siltation propagation paths. The study’s findings indicate the following: (1) Despite a relatively low overall siltation risk, regular pipeline inspection and maintenance is necessary. (2) A total of 22 critical nodes, primarily located in main pipelines or confluence manholes, exhibit high risk and require priority attention. (3) Siltation propagation shows significant chain characteristics, with main pipeline and junction node failures potentially leading to systemic crises. In the central Zhengzhou stormwater network presented in this paper, high-risk factors are concentrated in a southern downstream outlet caused by an edge identified as critical that propagates siltation risks to the downstream nodes, forming a long path with elevated risk levels. This study provides crucial insights into the risk management and prevention of sedimentation and blockages in urban drainage networks, not only offering important technical references and a solid scientific basis for pipeline maintenance and network upgrades—thereby contributing to drainage system planning and the enhancement of urban flood protection capabilities—but also serving as a valuable technical reference for improving the overall resilience and operational efficiency of drainage systems. Full article

(This article belongs to the Special Issue Urban Flood Frequency Analysis and Risk Assessment)

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25 pages, 5719 KiB

Open AccessArticle

Investigation of the Interaction of Water and Energy in Multipurpose Bio-Solar Green Roofs in Mediterranean Climatic Conditions

by Behrouz Pirouz, Seyed Navid Naghib, Karolos J. Kontoleon, Baiju S. Bibin, Hana Javadi Nejad and Patrizia Piro

Water 2025, 17(7), 950; https://doi.org/10.3390/w17070950 (registering DOI) - 25 Mar 2025

Abstract

The advantages of green roofs and solar panels are numerous, but in dry periods, green roofs can place urban water resources under pressure, and the efficiency of solar panels can be affected negatively by high temperatures. In this context, our analysis investigated the [...] Read more.

The advantages of green roofs and solar panels are numerous, but in dry periods, green roofs can place urban water resources under pressure, and the efficiency of solar panels can be affected negatively by high temperatures. In this context, our analysis investigated the advantages of bio-solar green roofs and evaluated the impact of green roofs on solar panel electricity production and solar panels on green roof water consumption. The assessment was conducted through simulation in a selected case study located in Cosenza, a city with a Mediterranean climate, with solar panels covering 10% to 60% of the green roof. Analyses were performed on the power outputs of four kinds of photovoltaic panels: polycrystalline, monocrystalline, bifacial, and Passivated Emitter and Rear Contact (PERC). The energy production and shade frequencies were simulated using PVGIS 5.3 and PVSOL 2024 R3. The impact of photovoltaic (PV) shade on the water consumption of green roofs was evaluated by image processing of a developed code in MATLAB R2024b. Moreover, water–energy interconnections in bio-solar green roof systems were assessed using the developed dynamic model in Vensim PLE 10.2.1. The results revealed that the water consumption by the green roof was reduced by 30.8% with a bio-solar coverage area of 60%. However, the electricity production by the PV panel was enhanced by about 4% with bio-solar green roofs and was at its maximum at a coverage rate of 50%. This investigation demonstrates the benefits of bio-solar green roofs, which can generate more electricity and require less irrigation. Full article

(This article belongs to the Special Issue Decision-Making Theory and Methodology for Water, Energy and Food Security, 2nd Edition)

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22 pages, 18090 KiB

Open AccessArticle

Hydrogeological Assessment and Steady-State Groundwater Flow Modeling for Groundwater Management in the Golina River Sub-Basin, Northern Ethiopia, Using MODFLOW 6

by Hindeya Gebru, Tesfamichael Gebreyohannes, Ermias Hagos and Nicola Perili

Water 2025, 17(7), 949; https://doi.org/10.3390/w17070949 (registering DOI) - 25 Mar 2025

Abstract

Unsustainable groundwater extraction for domestic and agricultural purposes, particularly crop irrigation, is leading to dramatic reductions in the quantity and quality of groundwater in many developing countries, including Ethiopia. Assessing and predicting groundwater responses to hydraulic stress caused by overexploitation related to anthropogenic [...] Read more.

Unsustainable groundwater extraction for domestic and agricultural purposes, particularly crop irrigation, is leading to dramatic reductions in the quantity and quality of groundwater in many developing countries, including Ethiopia. Assessing and predicting groundwater responses to hydraulic stress caused by overexploitation related to anthropogenic activities and climate change are crucial for informing water management decisions. The aim of this study is to develop a three-dimensional steady-state groundwater flow model for the Golina River Sub-Basin to understand the relationship between groundwater recharge and groundwater pumping and their impacts under steady-state conditions from the perspective of groundwater management. The model was created using MODFLOW 6 and discretized into 345 rows and 444 columns with a grid resolution of 100 m by 100 m. The subsurface was modeled as two layers: a clastic alluvial layer overlying a weathered and fractured bedrock. The surface-water divide of the Golina River Sub-Basin was treated as a no-flow boundary. The initial values of horizontal hydraulic conductivity ranged from 0.001 m/day for rhyolite to 27.26 m/day for alluvial deposits. The aquifer recharge rates from the WetSpass model ranged from 1.08 × 10⁻³ to 2.25 × 10⁻⁴ m/day, and the discharge rates from the springs, hand-dug wells, and boreholes were 2.79 × 10⁴ m³/day, known flux boundaries. Sensitivity analysis revealed that the model is very sensitive to hydraulic conductivity, moderately sensitive to aquifer recharge, and less sensitive to groundwater pumping. Calibration was performed to match observed and simulated hydraulic heads of selected wells and achieved a correlation coefficient of 0.998. The calibrated hydraulic conductivity ranged from 1.2 × 10⁻⁴ m/day for rhyolite to 20 m/day for gravel-dominated alluvial deposits. The groundwater flow direction is toward the southeast, and the water balance indicates a negligible difference between the total recharge (207,775.8297 m³/day, which is the water entering the aquifer system) and the total pumped volume (207,775.9373 m³/day, which is the water leaving the aquifer system). The scenario analysis showed that an increase in the pumping rate of 25%, 50%, and 75% would result in a decrease in the hydraulic head by 4.64 m, 10.18 m, and 17.38 m, respectively. A decrease in recharge of 25%, 50%, and 75% would instead result in hydraulic-head declines of 6 m, 15.29 m, and 46.97 m, respectively. Consequently, the findings of this study suggest that decision-makers should prioritize enhancing integrated groundwater management strategies to improve recharge rates within the aquifer system of the study area. Full article

(This article belongs to the Special Issue Groundwater Flow and Transport Modeling in Aquifer Systems)

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16 pages, 1657 KiB

Open AccessArticle

A Data-Driven Decision Support System for Wave Power Plant Location Selection

by Gunganist Kongklad, Nguyen Van Thanh, Apichart Pattanaporkratana, Nattaporn Chattham and Chawalit Jeenanunta

Water 2025, 17(7), 948; https://doi.org/10.3390/w17070948 (registering DOI) - 25 Mar 2025

Abstract

Vietnam has a coastline of over 3260 km and an exclusive economic zone extending 200 nautical miles, providing favorable conditions for the development of wave energy. Exploring and harnessing this endless energy source to maximize the use of the available resources is essential [...] Read more.

Vietnam has a coastline of over 3260 km and an exclusive economic zone extending 200 nautical miles, providing favorable conditions for the development of wave energy. Exploring and harnessing this endless energy source to maximize the use of the available resources is essential for sustainable economic development. According to research conducted by the Institute of Marine and Island Research, the total global exploitable wave energy capacity is 212 TWh per year, accounting for nearly 1% of the global total and 90% of Vietnam’s annual electricity consumption needs. However, selecting the optimal location to construct wave energy production plants requires the consideration of various criteria, including efficiency potential, economic and social, technological, transport and environment factors. In this research, the authors propose a hybrid MCDM model including a fuzzy analytic hierarchy process (FAHP) and Interactive Multi-Criteria Decision-Making method (TODIM) under a fuzzy environment for wave power plant location selection in Vietnam. A real-world application of the approach is given to showcase the effectiveness of the proposed method, where three potential locations are assessed based on 14 criteria. The research results propose priority locations for project implementation, while providing a scientific basis for policymakers and investors in the decision-making process. This study contributes to promoting the development of renewable energy and efficiently utilizing Vietnam’s marine resources. Full article

(This article belongs to the Special Issue Decision-Making Theory and Methodology for Water, Energy and Food Security, 2nd Edition)

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27 pages, 18176 KiB

Open AccessArticle

The Effects of Runoff and Erosion Hydrodynamics by Check Dams Under Different Precipitation Types in the Watershed of Loess Plateau

by Naichang Zhang, Yangfan Feng, Zhaohui Xia, Peng Li, Fan Yue, Yongxiang Cao, Pengfei Wang, Tian Wang, Xingyue Guo and Shixuan Zhou

Water 2025, 17(7), 947; https://doi.org/10.3390/w17070947 (registering DOI) - 25 Mar 2025

Abstract

As one of the most important soil and water conservation engineering measures, the check dam plays an important role in the process of soil erosion control on the Loess Plateau of China. Combined with the hydrodynamic model, the regulation effects of runoff and [...] Read more.

As one of the most important soil and water conservation engineering measures, the check dam plays an important role in the process of soil erosion control on the Loess Plateau of China. Combined with the hydrodynamic model, the regulation effects of runoff and erosion hydrodynamics on check dams was studied under different precipitation types in the Xiliugou watershed of Loess Plateau. The Xiliugou watershed is dominated by the four precipitation types, short duration and small total amounts (P1), long duration and small total amounts (small total amounts), short duration and larger total amounts (P3) and short duration and largest total amounts (P4). The results show that the peak flow time may lag behind in the upper and middle reaches, while it may be advanced in the downstream in the parallel layout of the dam system watershed. The check dam system plays a significant role in reducing runoff and erosion hydrodynamics. The construction of check dams results in a significant reduction in the peak flow under the P2 precipitation type, reaching 39.41%. For the average maximum velocity, runoff shear stress and runoff power along the main channel, the P2 precipitation type results in a significant reduction in hydrodynamics in the dam system watershed, reaching 16.72%, 21.44% and 33.10%, respectively. However, for peak velocity, runoff shear stress and runoff power along the main channel, the P3 precipitation type results in a significant reduction in hydrodynamics in the dam system watershed, reaching 14.34%, 19.99% and 31.42%, respectively. The regulation effect of the check dam system on erosion hydrodynamics is stronger in the middle reaches and gradually weakened in the lower reaches of the watershed. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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17 pages, 2828 KiB

Open AccessArticle

Enhanced Landslide Risk Evaluation in Hydroelectric Reservoir Zones Utilizing an Improved Random Forest Approach

by Aichen Wei, Hu Ke, Shuni He, Mingcheng Jiang, Zeying Yao and Jianbo Yi

Water 2025, 17(7), 946; https://doi.org/10.3390/w17070946 (registering DOI) - 25 Mar 2025

Abstract

Landslides on reservoir slopes are one of the key geologic hazards that threaten the safe operation of hydropower plants. The aim of our study was to reduce the limitations of the existing methods of landslide risk assessment when dealing with complex nonlinear relationships [...] Read more.

Landslides on reservoir slopes are one of the key geologic hazards that threaten the safe operation of hydropower plants. The aim of our study was to reduce the limitations of the existing methods of landslide risk assessment when dealing with complex nonlinear relationships and the difficulty of quantifying the uncertainty of predictions. We established a multidimensional system of landslide risk assessment that covers geological settings, meteorological conditions, and the ecological environment, and we proposed a model of landslide risk assessment that integrates Bayesian theory and a random forest algorithm. In addition, the model quantifies uncertainty through probability distributions and provides confidence intervals for the prediction results, thus significantly improving the usefulness and reliability of the assessment. In this study, we adopted the Gini index and SHAP (SHapley Additive exPlanations) value, an analytical methodology, to reveal the key factors affecting slope stability and their interaction. The empirical results obtained show that the model effectively identifies the key risk factors and also provides an accurate prediction of landslide risk, thus enhancing scientific and targeted decision making. This study offers strong support for managing landslide risk and providing a more solid guarantee of the safe operation of hydropower station sites. Full article

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31 pages, 4856 KiB

Open AccessArticle

Influence of Geographical Locations on Drinking Water Quality in Rural Pavlodar Region, Kazakhstan

by Raikhan Beisenova, Jiquan Chen, Maira Kussainova, Kamshat Tussupova, Rumiya Tazitdinova, Nurul Mujahid and Zhanar Rakhymzhan

Water 2025, 17(7), 945; https://doi.org/10.3390/w17070945 (registering DOI) - 24 Mar 2025

Abstract

Drinking water quality in rural areas is impacted by industrial and agricultural runoff, water treatment infrastructure, and household economic conditions. This study explores the relationship between drinking water quality, water sources, and land cover types in northeastern Kazakhstan. The Water Quality Index (WQI) [...] Read more.

Drinking water quality in rural areas is impacted by industrial and agricultural runoff, water treatment infrastructure, and household economic conditions. This study explores the relationship between drinking water quality, water sources, and land cover types in northeastern Kazakhstan. The Water Quality Index (WQI) was calculated for each household and village using the Horton Equation. Land cover was mapped using Sentinel-2 Level-2A imagery. Statistical differences among villages were analyzed through one-way ANOVA and t-tests. A Structural Equation Model (SEM) was built using Maximum Likelihood estimators, with significance set at p < 0.05. Significant variations in manganese, hydrocarbonates, and chlorides were observed based on the distance from the Irtysh River and water sources. Grasslands had the greatest influence on water parameters (−14.89), followed by croplands (5.96), urban lands (2.15), and other land types (2), with forests having the least effect. Biological indicators, such as Actinomycetes sp., were significantly correlated with forests (2.32) and other land cover types. Grasslands reduce mineral content in groundwater, while croplands and forests contribute to mineral enrichment, particularly nitrates from croplands. Urban areas increase chemical loads in groundwater, and manganese levels decrease with distance from the Irtysh River. Chlorides and hydrocarbonates are highest near the river. Rural water treatment infrastructure should be improved, stricter pollution controls should be enforced, and sustainable land use practices should be promoted to reduce agricultural and urban runoff. Additionally, economic incentives for household filtration, regular water quality monitoring, and a coordinated watershed management approach can enhance long-term water security. Full article

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

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18 pages, 667 KiB

Open AccessArticle

Stakeholders’ Perceptions on the Formulation of Climate Change Adaptation Policy and Governance: A Case of the Water Sector in the Raymond Mhlaba and Ngqushwa Local Municipalities, South Africa

by John Moyo Majahana, Ahmed Mukalazi Kalumba, Sonwabo Perez Mazinyo and Leocadia Zhou

Water 2025, 17(7), 944; https://doi.org/10.3390/w17070944 (registering DOI) - 24 Mar 2025

Abstract

Given the persistent drought disasters, the Amathole District Municipality grapples with severe water scarcity issues, particularly affecting local municipalities such as Raymond Mhlaba and Ngqushwa. Consequently, the municipalities are challenged by severe climate change and governance-related water scarcity. Thus, investigating climate change adaptation [...] Read more.

Given the persistent drought disasters, the Amathole District Municipality grapples with severe water scarcity issues, particularly affecting local municipalities such as Raymond Mhlaba and Ngqushwa. Consequently, the municipalities are challenged by severe climate change and governance-related water scarcity. Thus, investigating climate change adaptation policy formulation and governance from the perspective of local communities can provide valuable insights into effective climate change adaptation governance. Employing a mixed research approach, this study investigates stakeholders’ perceptions of the formulation process and approaches to climate change adaptation policy and governance in the water sector using narrative analysis and descriptive statistics survey data. The study revealed that policy formulation is challenged by a bureaucratic water governance system, as most of the respondents (70%) were uncertain about their roles in climate change adaptation policy formulation, compared to 30% who were able to partially articulate their roles. Thus, 66% of respondents indicated that they were not involved in climate change adaptation in water resource management. This underscores that most stakeholders are ‘locked out’ from divulging their decisions in climate change adaptation policy formulation. This study will help municipalities develop proper climate change adaptation strategies based on local knowledge to enhance their resilience against climate change disasters. Full article

(This article belongs to the Section Urban Water Management)

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21 pages, 3278 KiB

Open AccessArticle

Modeling Nitrogen Migration Characteristics in Cool-Season Turf Grass Soils via HYDRUS-2D

by Rui Li, Yueying Du, Longfei Liu, Wangxin Su, Ke Tu, Yonghua Li and Yang Liu

Water 2025, 17(7), 943; https://doi.org/10.3390/w17070943 (registering DOI) - 24 Mar 2025

Abstract

In order to study the leaching of exogenous nitrogen during green space management and maintenance, the parameters of the model were calibrated through field monitoring and grow box simulation experiments, and the Model for Studying Nitrogen Transport in Green Space Ecosystems was established [...] Read more.

In order to study the leaching of exogenous nitrogen during green space management and maintenance, the parameters of the model were calibrated through field monitoring and grow box simulation experiments, and the Model for Studying Nitrogen Transport in Green Space Ecosystems was established by using HYDRUS-2D software. Results showed that the model is highly reliable for simulating nitrogen transport in microtopography, with R² values greater than 0.9 and RMSE values below 5. Slope gradient was positively correlated with horizontal nitrogen differences (ammonium and nitrate nitrogen) and negatively correlated with vertical differences (p < 0.05), while nitrogen application was positively correlated with both horizontal and vertical differences in nitrate nitrogen and negatively correlated with ammonium nitrogen (p < 0.05). The vertical differences of soil ammonium nitrogen exhibited a significant negative correlation with slope (−0.837 to −0.851), while the horizontal differences of nitrate nitrogen showed a significant positive correlation, with correlation coefficients of 0.965 and 0.967 for surface and subsurface soils, respectively. The increasing nitrogen application rate exacerbated these discrepancies, with the highest nitrogen treatment (0.312 g) exhibiting the most pronounced differential effects. Notably, the horizontal variation in nitrate nitrogen reached 6.9-fold that of ammonium nitrogen, while the vertical discrepancy demonstrated a 7.0-fold magnitude relative to ammonium nitrogen levels. Full article

19 pages, 3683 KiB

Open AccessReview

Bibliometric and Visualization Analysis of Groundwater Heavy Metal Pollution Research Based on Web of Science

by Yizhen Xie, Wenchao Jia, Min Tan, Yu Feng, Shijun Fu and Dongdong Zhang

Water 2025, 17(7), 942; https://doi.org/10.3390/w17070942 (registering DOI) - 24 Mar 2025

Abstract

Groundwater is an important part of maintaining the balance of the ecosystem and one of the main freshwater resources of human society. It has therefore attracted much attention in the field of the environment, in order to gain an in-depth understanding of the [...] Read more.

Groundwater is an important part of maintaining the balance of the ecosystem and one of the main freshwater resources of human society. It has therefore attracted much attention in the field of the environment, in order to gain an in-depth understanding of the research hotspots, cooperation networks and development processes in the field of groundwater heavy metal pollution remediation, and objectively reflect the scientific contributions and influences of relevant countries (regions), institutions and individuals in this field. To provide researchers with a comprehensive understanding of research trends in the field of heavy metal contamination in groundwater, this study analyzes 8147 publications from 1998 to 2024 using the Web of Science Core Collection database from the ISI Web of Knowledge. Bibliometric analysis was conducted with the data visualization tools CiteSpace and HistCite Pro. The study examines key aspects such as major research institutions, and research directions, offering insights into the application and development of groundwater heavy metal pollution remediation since 1998. The bibliometric visualization analysis of the literature in this field provides valuable insights into research directions, development trends, and emerging hotspots, offering guidance for future studies on groundwater heavy metal contamination. The analysis indicates that China and India have made significant contributions to groundwater heavy metal research. Zinc, copper, lead, and cadmium are the primary water pollutants and key research targets. However, many challenges remain in heavy metal detection, including the migration and transformation pathways of heavy metals in water bodies, interference from different matrices, and the complex chemical forms in which heavy metals exist. Future research on groundwater heavy metals will continue to focus on pollution mechanisms, source identification, risk assessment and management, bioremediation, and treatment technologies. Efforts will be made to develop technologies that enable rapid, high-precision detection and efficient heavy metal recovery. Full article

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

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21 pages, 12314 KiB

Open AccessArticle

Modeling and Validating Saltwater Intrusion Dynamics by Self-Potential: A Laboratory Perspective

by Meryem Fanidi, Yi-An Cui, Jing Xie, Ahmed Abdelreheem Khalil and Syed Muzyan Shahzad

Water 2025, 17(7), 941; https://doi.org/10.3390/w17070941 (registering DOI) - 24 Mar 2025

Abstract

Saltwater intrusion (SWI) in coastal aquifers poses a significant threat to freshwater resources, exacerbated by climate change and rising sea levels. This study investigates SWI dynamics using laboratory experiments, geophysical monitoring with the self-potential (SP) method, and numerical simulations to assess the impact [...] Read more.

Saltwater intrusion (SWI) in coastal aquifers poses a significant threat to freshwater resources, exacerbated by climate change and rising sea levels. This study investigates SWI dynamics using laboratory experiments, geophysical monitoring with the self-potential (SP) method, and numerical simulations to assess the impact of varying salt concentrations (7 g/L and 35 g/L) on intrusion rates and electrochemical responses. Laboratory experiments were conducted in a custom-designed sandbox model, with SP data collected in real time using a 192-electrode system. Numerical simulations were performed to replicate experimental conditions and validate the model’s predictions. Results show that salt concentration significantly influences intrusion rates and SP responses. In low-salinity systems (7 g/L), SP values increased gradually from 0 mV to 20 mV, with a slow intrusion rate of 0.034 m/h. In contrast, moderate-salinity systems (35 g/L) exhibited rapid SP changes (0 mV to 5 mV) and a faster intrusion rate of 0.1 m/h. Sharp SP anomalies near the intrusion source, with values dropping from 10 mV to −40 mV, were observed in low-salinity systems, highlighting localized charge imbalances. The model’s performance was evaluated using relative RMSE, showing a good fit in Experiment (1) (RMSE = 5.00%) and acceptable results for Experiment (2) (RMSE = 23.45%). These findings demonstrate the potential of the SP method for real-time monitoring of SWI and provide insights for improving management strategies in coastal aquifers. Full article

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

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33 pages, 71047 KiB

Open AccessArticle

Multi-Model Assessment to Analyze Flow Alteration Under the Changing Climate in a Medium-Sized River Basin in Nepal: A Case Study of the Kankai River Basin

by Manan Sharma, Rajendra Prasad Singh and Samjhana Rawat Sharma

Water 2025, 17(7), 940; https://doi.org/10.3390/w17070940 (registering DOI) - 24 Mar 2025

Abstract

The medium river basins (MRBs) in Nepal originate from mid-hills. These medium-range rivers are typically non-snow-fed, relying on rain and other water sources. These rivers are typically small, and the sizes of medium river basins vary between 500 and 5000 km². [...] Read more.

The medium river basins (MRBs) in Nepal originate from mid-hills. These medium-range rivers are typically non-snow-fed, relying on rain and other water sources. These rivers are typically small, and the sizes of medium river basins vary between 500 and 5000 km². These MRBs are often used for irrigation and other agricultural purposes. In this analysis, we first set up, calibrated, and validated three hydrological models (i.e., HBV, HEC HMS, and SWAT) at the Kankai River Basin (one MRB in eastern Nepal). Then, the best-performing SWAT hydrological model was forced with cutting-edge climate models (CMs) using thirteen CMIP6 models under four shared socioeconomic pathways (SSPs). We employed ten bias correction (BC) methods to capture local spatial variability in precipitation and temperature. Finally, the likely streamflow alteration during two future periods, i.e., the near-term timeframe (NF), spanning from 2031 to 2060, and the long-term timeframe (FF), covering the years 2071 to 2100, were evaluated against the historical period (baseline: 1986–2014), considering the uncertainties associated with the choice of CMs, BC methods, or/and SSPs. The study results confirm that there will not be any noticeable shifts in seasonal variations in the future. However, the magnitude is projected to alter substantially. Overall, the streamflow is estimated to upsurge during upcoming periods. We observed that less deviation is expected in April, i.e., around +5 to +7% more than the baseline period. Notably, a higher percentage increment is projected during the monsoon season (June–August). During the NF (FF) period, the flow alteration will be around +20% (+40%) under lower SSPs, whereas the flow alteration will be around +30% (+60%) under higher SSPs during high flow season. Thus, the likelihoods of flooding, inundation, and higher discharge are projected to be quite high in the coming years. Full article

(This article belongs to the Special Issue Water Resources, Environment, and Ecosystems: Application of New Technology)

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24 pages, 4309 KiB

Open AccessArticle

Predicting Offshore Oil Slick Formation: A Machine Learning Approach Integrating Meteoceanographic Variables

by Simone C. Streitenberger, Estevão L. Romão, Fabrício A. Almeida, Antonio C. Zambroni de Souza, Aloisio E. Orlando, Jr. and Pedro P. Balestrassi

Water 2025, 17(7), 939; https://doi.org/10.3390/w17070939 (registering DOI) - 24 Mar 2025

Abstract

The presence of oil slicks in the ocean presents significant environmental and regulatory challenges for offshore oil processing operations. During primary oil–water separation, produced water is discharged into the ocean, carrying residual oil, which is measured using the total oil and grease (TOG) [...] Read more.

The presence of oil slicks in the ocean presents significant environmental and regulatory challenges for offshore oil processing operations. During primary oil–water separation, produced water is discharged into the ocean, carrying residual oil, which is measured using the total oil and grease (TOG) method. The formation and spread of oil slicks are influenced by metoceanographic variables, including wind direction (WD), wind speed (WS), current direction (CD), current speed (CS), wind wave direction (WWD), and peak period (PP). In Brazil, regulatory limits impose sanctions on companies when oil slicks exceed 500 m in length, making accurate prediction of their occurrence and extent crucial for offshore operators. This study follows three main stages. First, the performance of five machine learning classification algorithms is evaluated, selecting the most efficient method based on performance metrics from a Brazilian company’s oil slick database. Second, the best-performing model is used to analyze the influence of metoceanographic variables and TOG levels on oil slick occurrence and detection probability. Finally, the third stage examines the extent of detected oil slicks to identify key contributing factors. The prediction results enhance decision-support frameworks, improving monitoring and mitigation strategies for offshore oil discharges. Full article

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20 pages, 8444 KiB

Open AccessArticle

Distribution Characteristics of Spring Maize Meteorological Drought in Different Climatic Regions of Inner Mongolia Based on Standardized Precipitation Evapotranspiration Index

by Xiujuan Yang, Shuaishuai Qiao, Feng Yang, Yuyuan Huang, Congying Han, Xiao Chang, Shuiyuan Hao, Hui Qian, Xinwei Feng and Na Li

Water 2025, 17(7), 938; https://doi.org/10.3390/w17070938 (registering DOI) - 24 Mar 2025

Abstract

Drought is a major meteorological disaster that affects the growth of spring maize in Inner Mongolia. Understanding the spatiotemporal characteristics of drought is crucial for maintaining crop production. This study categorized Inner Mongolia into five climatic regions based on geography and climate characteristics: [...] Read more.

Drought is a major meteorological disaster that affects the growth of spring maize in Inner Mongolia. Understanding the spatiotemporal characteristics of drought is crucial for maintaining crop production. This study categorized Inner Mongolia into five climatic regions based on geography and climate characteristics: hyper-arid, arid, semi-arid, dry and semi-humid, and moist and semi-humid, reflecting Regions I to V, respectively. Based on data collected from 107 meteorological stations, the standardized precipitation evapotranspiration index (SPEI) was used to assess the characteristics of drought occurrence in different climatic regions during the spring maize growing season over the past 60 years, as well as the impact of drought on yield. SPEI decreased across all regions during growth periods, with mid-growth stages showing the smallest decline and a slight slowdown in drought severity. Spatially, 15 stations showed reduced drought during the early growth stage, which increased to 20 stations during the mid-growth stage. The overall drought trend of intensification was obtained across various climate regions, with Region I showing the most severe drought. The drought frequency during the growth period of spring maize ranged from 20% to 42%, and the drought frequency decreased from light drought, moderate drought, and severe drought to extreme drought. The drought range in each growth stage increased, with localized and regional drought dominating the region. The drought intensity also increased. Precipitation is the main factor affecting spring maize yield, and water replenishment during the early and middle stages of growth is crucial. These findings provide a basis for efficient water resource management in the region. Full article

(This article belongs to the Special Issue Effect of Climate Change on Water Availability in Arid and Semi-arid Regions)

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23 pages, 29128 KiB

Open AccessArticle

Flood Susceptibility Analysis with Integrated Geographic Information System and Analytical Hierarchy Process: A Multi-Criteria Framework for Risk Assessment and Mitigation

by Sujan Shrestha, Dewasis Dahal, Bishal Poudel, Mandip Banjara and Ajay Kalra

Water 2025, 17(7), 937; https://doi.org/10.3390/w17070937 (registering DOI) - 23 Mar 2025

Abstract

Flooding is among the most destructive natural disasters globally, and it inflicts severe damage on both natural environments and human-made structures. The frequency of floods has been increasing due to unplanned urbanization, climate change, and changes in land use. Flood susceptibility maps help [...] Read more.

Flooding is among the most destructive natural disasters globally, and it inflicts severe damage on both natural environments and human-made structures. The frequency of floods has been increasing due to unplanned urbanization, climate change, and changes in land use. Flood susceptibility maps help identify at-risk areas, supporting informed decisions in disaster preparedness, risk management, and mitigation. This study aims to generate a flood susceptibility map for Davidson County of Tennessee using an integrated geographic information system (GIS) and analytical hierarchical process (AHP). In this study, ten flood causative factors are employed to generate flood-prone zones. AHP, a form of weighted multi-criteria decision analysis, is applied to assess the relative impact weights of these flood causative factors. Subsequently, these factors are integrated into ArcGIS Pro (Version 3.3) to create a flood susceptibility map for the study area using a weighted overlay approach. The resulting flood susceptibility map classified the county into five susceptibility zones: very low (17.48%), low (41.89%), moderate (37.53%), high (2.93%), and very high (0.17%). The FEMA flood hazard map of Davidson County is used to validate the flood susceptibility map created from this approach. Ultimately, this comparison reinforced the accuracy and reliability of the flood susceptibility assessment for the study area using integrated GIS and AHP approach. Full article

(This article belongs to the Special Issue Advancing the Monitoring and Modelling of Freshwater Systems with New Remote Sensing Technologies)

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25 pages, 3496 KiB

Open AccessArticle

Overviewing the Machine Learning Utilization on Groundwater Research Using Bibliometric Analysis

by Kayhan Bayhan, Eyyup Ensar Başakın, Ömer Ekmekcioğlu, Quoc Bao Pham and Hone-Jay Chu

Water 2025, 17(7), 936; https://doi.org/10.3390/w17070936 (registering DOI) - 23 Mar 2025

Abstract

Groundwater, which constitutes 95% of the world’s freshwater resources, is widely used for drinking and domestic water supply, agricultural irrigation, energy production, bottled water production, and commercial use. In recent years, due to pressures from climate change and excessive urbanization, a noticeable decline [...] Read more.

Groundwater, which constitutes 95% of the world’s freshwater resources, is widely used for drinking and domestic water supply, agricultural irrigation, energy production, bottled water production, and commercial use. In recent years, due to pressures from climate change and excessive urbanization, a noticeable decline in groundwater levels has been observed, particularly in arid and semi-arid regions. The corresponding changes have been analyzed using a diverse range of methodologies, including data-driven modeling techniques. Recent evidence has shown a notable acceleration in the utilization of such advanced techniques, demonstrating significant attention by the research community. Therefore, the major aim of the present study is to conduct a bibliometric analysis to investigate the application and evolution of machine learning (ML) techniques in groundwater research. In this sense, studies published between 2000 and 2023 were examined in terms of scientific productivity, collaboration networks, research themes, and methods. The findings revealed that ML techniques offer high accuracy and predictive capacity, especially in water quality, water level estimation, and pollution modeling. The United States, China, and Iran stand out as leading countries emphasizing the strategic importance of ML in groundwater management. However, the outcomes demonstrated that a low level of international cooperation has led to deficiencies in solving transboundary water problems. The study aimed to encourage more widespread and effective use of ML techniques in water management and environmental planning processes and drew attention to the importance of transparent and interpretable algorithms, with the potential to yield rewarding opportunities in increasing the adoption of corresponding technologies by decision-makers. Full article

(This article belongs to the Topic Natural Hazards and Environmental Challenges in the Anthropocene Age, 2nd Edition)

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22 pages, 1279 KiB

Open AccessArticle

Enhancement of Tetradesmus obliquus Adsorption for Heavy Metals Through Lysine Addition: Optimization and Competitive Study

by Qun Wei, Haijian Sun, Haoqi Qi, Conghan Wang, Gairen Yang and Xiangmeng Ma

Water 2025, 17(7), 935; https://doi.org/10.3390/w17070935 (registering DOI) - 22 Mar 2025

Abstract

Heavy metal wastewater often contains multiple metal ions, and competition among them reduces the adsorption efficiency of microalgae. Enhancing this efficiency is crucial for improving heavy metal removal. This study optimized lysine addition to facilitating the formation of a ternary complex between microalgae, [...] Read more.

Heavy metal wastewater often contains multiple metal ions, and competition among them reduces the adsorption efficiency of microalgae. Enhancing this efficiency is crucial for improving heavy metal removal. This study optimized lysine addition to facilitating the formation of a ternary complex between microalgae, lysine, and heavy metals, thereby enhancing adsorption in both single- and mixed-metal systems. In a single-metal system at 64 mg/L, lysine improved the removal rates of copper, zinc, and cadmium by 13.96%, 41.21%, and 33.26%, respectively. In binary systems (Cu-Zn, Cu-Cd, and Cu-Pb) at 32 mg/L, lysine increased copper adsorption by 11.81%, 15.71%, and 25.25%, while improving zinc, cadmium, and lead adsorption by 15.41%, 12.51%, and 3.93%, respectively. Competitive adsorption analysis revealed that lead most strongly inhibited copper adsorption, while copper significantly suppressed zinc adsorption. Mechanistic investigations using 3D-EEM, FTIR, and XPS demonstrated that humic substances in the extracellular polymeric substances (EPSs) of microalgae play a key role in lysine binding. This interaction increases the number of carboxyl functional groups on the cell surface, thereby enhancing the microalgae’s capacity to adsorb heavy metals. Full article

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

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14 pages, 2961 KiB

Open AccessArticle

Research on the Features and Driving Factors of Shallow Groundwater Quality in Arid Areas, Northwest China

by Long Wang, Nan Yang, Yang Zhao and Qianqian Zhang

Water 2025, 17(7), 934; https://doi.org/10.3390/w17070934 (registering DOI) - 22 Mar 2025

Abstract

Given the increasing threat of groundwater pollution, comprehending the trends and influencing factors of groundwater quality variation is essential for effective mitigation strategies. This study addresses groundwater quality variations in the Beichuan River, a critical area in China’s arid region. Using hydrochemical analysis [...] Read more.

Given the increasing threat of groundwater pollution, comprehending the trends and influencing factors of groundwater quality variation is essential for effective mitigation strategies. This study addresses groundwater quality variations in the Beichuan River, a critical area in China’s arid region. Using hydrochemical analysis and multivariate statistics, we identified key factors influencing groundwater quality. Groundwater is mildly alkaline, with HCO₃⁻-Ca as the dominant hydrochemical type. The concentrations of major ions increase during the high-flow period due to rainfall effects. The dissolution of rock salt primarily contributes to the presence of Na⁺ and Cl⁻ ions. Meanwhile, the weathering of silicate and carbonate rocks is the main origin of Ca²⁺, Mg²⁺, and HCO₃⁻ ions. Additionally, the dissolution of evaporite rocks is identified as the principal source of SO₄²⁻. Human activities, particularly sewage discharge and fertilization, significantly contribute to nitrate contamination. Principal component analysis revealed that the weathering of rocks and industrial activities are the main controlling factors during the high-flow season, while the hydrochemistry of groundwater during the low-flow season is mainly influenced by the weathering of silicate rocks, evaporite rocks, and rock salt. Our findings provide a scientific basis for preventing groundwater quality deterioration and ecological environmental protection in arid regions. Full article

(This article belongs to the Special Issue Water Quality Assessment of River Basins)

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