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Water, Volume 17, Issue 13 (July-1 2025) – 203 articles

Cover Story (view full-size image): Early morning ice cover over Sixteen Mile Creek in Milton, Canada, is recorded on 20 February 2024. Water is flowing toward the camera and the channel width is almost 20 m at the widest point in this section. Usually, the channel is completely covered in 10+ cm of ice by mid-February. Milder winters lead to less ice cover and thus changes shear stress at the bed, which has consequences for sediment transport and aquatic habitats. View this paper
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16 pages, 5784 KiB  
Article
Enhanced Early Warning Threshold Setting for Dam Safety Monitoring Based on M-Estimation and Confidence Interval Method
by Peilin Dai, Xing Li, Guochun Hua and Yanling Li
Water 2025, 17(13), 2040; https://doi.org/10.3390/w17132040 - 7 Jul 2025
Viewed by 259
Abstract
Accurate online identification of abnormal sudden change observations is crucial for ensuring data reliability and has been a key challenge in dam safety monitoring. Traditional methods, such as those based on the Pauta criterion, often fail to effectively identify anomalies in complex data [...] Read more.
Accurate online identification of abnormal sudden change observations is crucial for ensuring data reliability and has been a key challenge in dam safety monitoring. Traditional methods, such as those based on the Pauta criterion, often fail to effectively identify anomalies in complex data sequences like step-type and oscillatory-type data, primarily due to unreasonable early warning threshold settings. To address this issue, this paper introduces a novel method for setting early warning thresholds by combining the scale estimator ST based on the location M-estimator with the confidence interval radius D derived from predicted values, thereby constructing the MZ criterion with a threshold of 3ST+D. The proposed model demonstrates strong resistance to outliers and good robustness, effectively improving the accuracy of online anomaly identification for various data sequences. The MZ standard achieves a false alarm and missed detection rate of less than 10% in the monitoring data of the XB hydropower plant, which is a significant improvement in detection accuracy compared to the traditional Pauta standard. Engineering applications have shown that the MZ criterion-based identification method achieves a low misjudgment and omission rate, high recognition accuracy, and is highly reliable for online dam safety monitoring. This method holds significant value for both theoretical research and practical engineering applications. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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21 pages, 13290 KiB  
Article
Watershed Prioritization with Respect to Flood Susceptibility in the Indian Himalayan Region (IHR) Using Geospatial Techniques for Sustainable Water Resource Management
by Ashish Mani, Ruchi Badola, Maya Kumari, Varun Narayan Mishra, Kgabo Humphrey Thamaga, Fahdah Falah Ben Hasher and Mohamed Zhran
Water 2025, 17(13), 2039; https://doi.org/10.3390/w17132039 - 7 Jul 2025
Viewed by 864
Abstract
The rising demand for freshwater, driven by population growth, economic development, and climate change, necessitates proactive watershed management. This study focuses on prioritizing the watersheds of the Doon Valley in the Indian Himalayan Region (IHR) using geospatial techniques. It involves a detailed morphometric [...] Read more.
The rising demand for freshwater, driven by population growth, economic development, and climate change, necessitates proactive watershed management. This study focuses on prioritizing the watersheds of the Doon Valley in the Indian Himalayan Region (IHR) using geospatial techniques. It involves a detailed morphometric analysis incorporating hydrological and topographical parameters, ranking the watersheds using the compound factor value (CFV), and prioritizing them based on the given CFV. The Doon Valley watersheds exhibit dendritic to parallel drainage patterns and moderate relief. The study identifies the Suswa watershed as the most susceptible, necessitating urgent conservation attempts to mitigate soil erosion and ensure sustainable land use. In contrast, the Song watershed, characterized by steep slopes and high relief, requires targeted management strategies to control rapid runoff and prevent potential flooding. The Asan watershed, with a medium priority classification, also requires intervention to prevent ecological degradation. Prioritization based on the CFV provides a strategic framework for targeted management, offering valuable insights for policymakers and planners. This research supports sustainable watershed management by guiding effective conservation practices and addressing the specific needs of each watershed. Full article
(This article belongs to the Special Issue The Interrelationship Between Climate Change, Human Activities and Hydrological Processes (3rd Edition))
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24 pages, 3815 KiB  
Article
Evaluating Natural Attenuation of Dissolved Volatile Organic Compounds in Shallow Aquifer in Industrial Complex Using Numerical Models
by Muhammad Shoaib Qamar, Nipada Santha, Sutthipong Taweelarp, Nattapol Ploymaklam, Morrakot Khebchareon, Muhammad Zakir Afridi and Schradh Saenton
Water 2025, 17(13), 2038; https://doi.org/10.3390/w17132038 - 7 Jul 2025
Viewed by 1101
Abstract
A VOC-contaminated shallow aquifer in an industrial site was investigated to evaluate its potential for natural attenuation. The shallow groundwater aquifer beneath the industrial site has been contaminated by dissolved volatile organic compounds (VOCs) such as trichloroethylene (TCE), cis-1,2-dichloroethylene (cis-DCE), [...] Read more.
A VOC-contaminated shallow aquifer in an industrial site was investigated to evaluate its potential for natural attenuation. The shallow groundwater aquifer beneath the industrial site has been contaminated by dissolved volatile organic compounds (VOCs) such as trichloroethylene (TCE), cis-1,2-dichloroethylene (cis-DCE), and vinyl chloride (VC) for more than three decades. Monitoring and investigation were implemented during 2011–2024, aiming to propose future groundwater aquifer management strategies. This study included groundwater borehole investigation, well installation monitoring, hydraulic head measurements, slug tests, groundwater samplings, and microbial analyses. Microbial investigations identified the predominant group of microorganisms of Proteobacteria, indicating biodegradation potential, as demonstrated by the presence of cis-DCE and VC. BIOSCREEN was used to evaluate the process of natural attenuation, incorporating site-specific parameters. A two-layer groundwater flow model was developed using MODFLOW with hydraulic conductivities obtained from slug tests. The site has an average hydraulic head of 259.6 m amsl with a hydraulic gradient of 0.026, resulting in an average groundwater flow velocity of 11 m/y. Hydraulic conductivities were estimated during model calibration using the PEST pilot point technique. A reactive transport model, RT3D, was used to simulate dissolved TCE transport over 30 years, which can undergo sorption as well as biodegradation. Model calibration demonstrated a satisfactory fit between observed and simulated groundwater heads with a root mean square error of 0.08 m and a correlation coefficient (r) between measured and simulated heads of 0.81, confirming the validity of the hydraulic conductivity distribution. The TCE plume continuously degraded and gradually migrated southward, generating a cis-DCE plume. The concentrations in both plumes decreased toward the end of the simulation period at Source 1 (located upstream), while BIOSCREEN results confirmed ongoing natural attenuation primarily by biodegradation. The integrated MODFLOW-RT3D-BIOSCREEN approach effectively evaluated VOC attenuation and plume migration. However, future remediation strategies should consider enhanced bioremediation to accelerate contaminant degradation at Source 2 and ensure long-term groundwater quality. Full article
(This article belongs to the Special Issue Application of Bioremediation in Groundwater and Soil Pollution)
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13 pages, 1338 KiB  
Article
Human Health Risk Assessment of Phenolic Contaminants in Lake Xingkai, China
by Liang Liu, Jinhua Gao, Yijun Sun, Yibo Sun, Handan Liu, Hongqing Sun and Guangyi Mu
Water 2025, 17(13), 2037; https://doi.org/10.3390/w17132037 - 7 Jul 2025
Viewed by 308
Abstract
Cresols are aromatic organic compounds widely used in industrial and agricultural production. They have been detected in large quantities in aquatic environments, posing health risks such as skin irritation, gastrointestinal stimulation, and chronic neurological effects. In this study, we investigated the exposure concentration [...] Read more.
Cresols are aromatic organic compounds widely used in industrial and agricultural production. They have been detected in large quantities in aquatic environments, posing health risks such as skin irritation, gastrointestinal stimulation, and chronic neurological effects. In this study, we investigated the exposure concentration of cresols in the water bodies of Lake Xingkai (i.e., Daxingkai and Xiaoxingkai Lakes) during four typical hydrological periods (30 April, 22 June, 5 September, and 1 November 2021), assessed the human health risk from phenolic contaminants using the mean value method, and determined the health risk of adult cresol exposure in the Lake Xingkai watershed based on local population exposure parameters. This study developed a water environmental pollution health risk assessment model based on the methodology proposed by the United States Environmental Protection Agency (US EPA). It further evaluated the health risks to humans posed by phenolic pollutants via the drinking water pathway. The results revealed that the concentration range of cresols in water bodies was between 5.91 × 10−1 ng·mL−1 and 6.68 ng·mL−1. The adult drinking water health risk values of cresols in the Lake Xingkai watershed were between 3.15 × 10−4 and 3.57 × 10−3, and all water samples from the 10 sites had hazard quotient (HQ) values less than 1, indicating that the non-carcinogen risk was small or negligible. The cresol HQ value in the water of Xiaoxingkai Lake was 4.6 times that found in Daxingkai Lake. Full article
(This article belongs to the Special Issue Biogeochemical Processes in Lakes, Ponds and Reservoirs of Urban Environments)
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24 pages, 14733 KiB  
Article
Disentangling the Source of Uncertainty in Monthly Streamflow Predictions: A Case Study of Riu Mannu di Narcao Basin, Sardinia Region, Italy
by Aklilu Assefa Tilahun, Ouafik Boulariah, Francesco Viola and Roberto Deidda
Water 2025, 17(13), 2036; https://doi.org/10.3390/w17132036 - 7 Jul 2025
Viewed by 403
Abstract
This study quantifies the uncertainty in monthly streamflow predictions under future climate scenarios in two periods (near and far future) for the Riu Mannu di Narcao basin in Sardinia, Italy. The sources of uncertainty include the hydrological model structure, model parameters, and variability [...] Read more.
This study quantifies the uncertainty in monthly streamflow predictions under future climate scenarios in two periods (near and far future) for the Riu Mannu di Narcao basin in Sardinia, Italy. The sources of uncertainty include the hydrological model structure, model parameters, and variability in climatic inputs derived from global and regional climate models (GCM-RCM coupling) and representative concentration pathways (RCPs). Three conceptual and lumped hydrological models (GR3M, ABCD, and IHACRES) were combined with four climate models and two RCPs (RCP 4.5 and RCP 8.5) to assess future streamflow. Monte Carlo simulations were performed to evaluate parameter uncertainty, and the analysis of variance (ANOVA) method was applied to quantify the different sources of uncertainty. The results reveal that, as a single source, GCM-RCM coupling is the largest contributor, accounting for 47.32% (54.64%) of total near (far) future monthly streamflow projection uncertainties, followed by the hydrological model structure at 16.02% (21.09%), RCP scenarios at 15.35% (8.54%), and parameter uncertainty at 0.79% (1.39%). A consistent decline in median monthly streamflow is projected, especially during winter months (December to February), raising a concern about water availability in the region. Our study quantified different sources of uncertainty in monthly streamflow predictions under climate change, disentangling the roles of the hydrological model, model parameters, climate model, and climate scenario for reliable future streamflow projections. Full article
(This article belongs to the Section Hydrology)
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21 pages, 4544 KiB  
Article
A Novel Activated Carbon-Based Composite for Enhanced Mercury Removal
by Hania Albatrni and Hazim Qiblawey
Water 2025, 17(13), 2035; https://doi.org/10.3390/w17132035 - 7 Jul 2025
Viewed by 298
Abstract
In designing an optimized activated carbon-based adsorbent, several key factors are crucial for its practical application in the industrial sector, including high BET surface area, strong adsorption capacity, selectivity, mechanical and thermal stability, regeneration potential, environmental impact, and cost-effectiveness. This study explores the [...] Read more.
In designing an optimized activated carbon-based adsorbent, several key factors are crucial for its practical application in the industrial sector, including high BET surface area, strong adsorption capacity, selectivity, mechanical and thermal stability, regeneration potential, environmental impact, and cost-effectiveness. This study explores the innovative approach of combining two chemical activating agents, potassium carbonate and sodium thiosulfate, to produce activated carbon with enhanced properties for improved mercury removal. At an activation temperature of 800 °C, the resulting adsorbent achieved a BET surface area of 2132.7 m2/g and a total pore volume of 1.08 cm3/g. Testing its mercury removal efficiency, the maximum adsorption capacity was 289 mg/g at room temperature. The Langmuir isotherm provided an excellent fit to the experimental data, indicating a monolayer adsorption process. Kinetic modeling revealed that the adsorption followed a pseudo-second-order model, consistent with chemisorption. The primary removal mechanism was found to involve complexation of mercury with oxygen and sulfur-containing functional groups, along with pore-filling physical adsorption. The adsorbent also showed a strong affinity for mercury even in the presence of other competing heavy metals. Furthermore, regeneration studies demonstrated the adsorbent’s effectiveness over five cycles. This research introduces a novel, environmentally friendly, and cost-efficient adsorbent for mercury removal. Full article
(This article belongs to the Special Issue Membrane and Other Innovative Technologies for Water Purification: Design, Development, and Application)
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17 pages, 4387 KiB  
Article
Algal Community Dynamics in Three Water Intakes of Poyang Lake: Implications for Drinking Water Safety and Management Strategies
by Bo Li, Jing Li, Yuehang Hu, Shaozhe Cheng, Shouchun Li and Xuezhi Zhang
Water 2025, 17(13), 2034; https://doi.org/10.3390/w17132034 - 7 Jul 2025
Viewed by 333
Abstract
This study aimed to investigate phytoplankton dynamics and water quality at three drinking water intakes (Duchang, Hukou, and Xingzi) in Poyang Lake through monthly monitoring from May 2023 to April 2024. The results showed that a total of 168 species of phytoplankton were [...] Read more.
This study aimed to investigate phytoplankton dynamics and water quality at three drinking water intakes (Duchang, Hukou, and Xingzi) in Poyang Lake through monthly monitoring from May 2023 to April 2024. The results showed that a total of 168 species of phytoplankton were identified in nine phyla, and there were significant spatial and temporal differences in the abundance of phytoplankton at the three waterworks intakes, with a spatial trend of annual mean values of Duchang > Xingzi > Hukou and a seasonal trend of summer and autumn > spring and winter. The dominant species of phytoplankton in the waterworks intakes of the three waterworks also showed obvious spatial and temporal differences. Cyanobacteria (particularly Pseudanabaena sp. and Microcystis sp.) dominated the phytoplankton communities during summer and autumn, demonstrating significant water degradation potential. In contrast, Cyclotella sp. prevailed in winter and spring assemblages. Based on water quality assessments at the three intake sites, the Duchang County intake exhibited year-round mild eutrophication with persistent mild cyanobacterial blooms (June–October), while the other two sites maintained no obvious bloom conditions. Further analyzing the toxic/odor-producing algal strains, the numbers of dominant species of Pseudanabaena sp. and Microcystis sp. in June–October in Duchang County both exceeded 1.0 × 107 cells·L−1. It is necessary to focus on their release of ATX-a (ichthyotoxin-a), 2MIB (2-Methylisoborneol), MCs (microcystins), etc., to ensure the safety of the water supply at the intake. Building upon these findings, we propose a generalized algal monitoring framework, encompassing three operational pillars: (1) key monitoring area identification, (2) high-risk period determination, and (3) harmful algal warnings. Each of these is substantiated by our empirical observations in Poyang Lake. Full article
(This article belongs to the Special Issue Freshwater Species: Status, Monitoring and Assessment)
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29 pages, 996 KiB  
Article
Enhancing Environmental Cognition Through Kayaking in Aquavoltaic Systems in a Lagoon Aquaculture Area: The Mediating Role of Perceived Value and Facility Management
by Yu-Chi Sung and Chun-Han Shih
Water 2025, 17(13), 2033; https://doi.org/10.3390/w17132033 - 7 Jul 2025
Viewed by 365
Abstract
Tainan’s Cigu, located on Taiwan’s southwestern coast, is a prominent aquaculture hub known for its extensive ponds, tidal flats, and lagoons. This study explored the novel integration of kayaking within aquavoltaic (APV) aquaculture ponds, creating a unique hybrid tourism landscape that merges industrial [...] Read more.
Tainan’s Cigu, located on Taiwan’s southwestern coast, is a prominent aquaculture hub known for its extensive ponds, tidal flats, and lagoons. This study explored the novel integration of kayaking within aquavoltaic (APV) aquaculture ponds, creating a unique hybrid tourism landscape that merges industrial land use (aquaculture and energy production) with nature-based recreation. We investigated the relationships among facility maintenance and safety professionalism (FM), the perceived value of kayaking training (PV), and green energy and sustainable development recognition (GS) within these APV systems in Cigu, Taiwan. While integrating recreation with renewable energy and aquaculture is an emerging approach to multifunctional land use, the mechanisms influencing visitors’ sustainability perceptions remain underexplored. Using data from 613 kayaking participants and structural equation modeling, we tested a theoretical framework encompassing direct, mediated, and moderated relationships. Our findings reveal that FM significantly influences both PV (β = 0.68, p < 0.001) and GS (β = 0.29, p < 0.001). Furthermore, PV strongly affects GS (β = 0.56, p < 0.001). Importantly, PV partially mediates the relationship between FM and GS, with the indirect effect (0.38) accounting for 57% of the total effect. We also identified significant moderating effects of APV coverage, guide expertise, and operational visibility. Complementary observational data obtained with underwater cameras confirm that non-motorized kayaking causes minimal ecological disturbance to cultured species, exhibiting significantly lower behavioral impacts than motorized alternatives. These findings advance the theoretical understanding of experiential learning in novel technological landscapes and provide evidence-based guidelines for optimizing recreational integration within production environments. Full article
(This article belongs to the Special Issue Aquaculture, Fisheries, Ecology and Environment)
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26 pages, 7033 KiB  
Article
Numerical Investigation into the Response of a Laterally Loaded Pile in Coastal and Offshore Slopes Considering Scour Effect
by Hao Zhang, Abubakarr Barrie, Fayun Liang and Chen Wang
Water 2025, 17(13), 2032; https://doi.org/10.3390/w17132032 - 7 Jul 2025
Viewed by 270
Abstract
This study investigates the response of laterally loaded pile foundations embedded in sloping beds under scour conditions, which is vital for the design and stability of coastal and offshore infrastructure like sea-crossing bridges, offshore wind turbines, and wharves. While previous studies have focused [...] Read more.
This study investigates the response of laterally loaded pile foundations embedded in sloping beds under scour conditions, which is vital for the design and stability of coastal and offshore infrastructure like sea-crossing bridges, offshore wind turbines, and wharves. While previous studies have focused on scour-affected pile performance in horizontal beds, this research expands the scope by incorporating sloped beds and corresponding scour effect, which are common in coastal and offshore environments. A three-dimensional finite element model was established to evaluate the pile foundation’s lateral load-bearing capacity under different slope and scour conditions, according to preceding flume tests on the mechanism of local scour around a pile in sloping bed. The results indicate that the lateral response of the pile is significantly influenced by the seabed slope and scour depth. A negatively inclined seabed weakens the interaction between the pile and the surrounding sediment, thereby reducing the lateral bearing capacity and bending moment. As the scour depth increases, the support provided by the soil further weakens, intensifying the reduction in lateral resistance. This effect is particularly pronounced for steep negative slopes, where the combined impact of slope and scour has a more significant detrimental effect. Full article
(This article belongs to the Special Issue Slope Stability Analyses and Landslide Risk Assessment Under Hydrodynamic Action)
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50 pages, 45416 KiB  
Article
Uncovering Anthropogenic Changes in Small- and Medium-Sized River Basins of the Southwestern Caspian Sea Watershed: Global Information System and Remote Sensing Analysis Using Satellite Imagery and Geodatabases
by Vladimir Tabunshchik, Aleksandra Nikiforova, Nastasia Lineva, Roman Gorbunov, Tatiana Gorbunova, Ibragim Kerimov, Abouzar Nasiri and Cam Nhung Pham
Water 2025, 17(13), 2031; https://doi.org/10.3390/w17132031 - 6 Jul 2025
Viewed by 522
Abstract
This study investigates the anthropogenic transformation of small- and medium-sized river basins within the Caspian Sea catchment. The basins of seven rivers—Sunzha, Sulak, Ulluchay, Karachay, Atachay, Haraz, and Gorgan—were selected as key study areas. For both the broader Caspian region, particularly its southwestern [...] Read more.
This study investigates the anthropogenic transformation of small- and medium-sized river basins within the Caspian Sea catchment. The basins of seven rivers—Sunzha, Sulak, Ulluchay, Karachay, Atachay, Haraz, and Gorgan—were selected as key study areas. For both the broader Caspian region, particularly its southwestern sector, and the selected study sites, trends in land cover types were analyzed, natural resource use practices were assessed, and population density dynamics were examined. Furthermore, a range of indices were calculated to quantify the degree of anthropogenic transformation, including the coefficient of anthropogenic transformation, the land degradation index, the urbanity index, the degree of anthropogenic transformation, coefficients of absolute and relative tension of the ecological and economic balance, and the natural protection coefficient. The study was conducted using geoinformation research methods and sets of geodata databases—the global LandScan population density database, the GHS Population Grid database, the ESRI land cover type dynamics database, and OpenStreetMap (OSM) data. The analysis was performed using the geoinformation programs QGIS and ArcGIS, and a large amount of literary and statistical data was additionally analyzed. It is shown that within the studied region, there has been a decrease in the number and density of the population, as a result of which the territories of river basins are experiencing an increasing anthropogenic impact, the woody type of land cover is decreasing, and the agricultural type is increasing. The most anthropogenically transformed river basins are Karachay, Haraz, and Gorgan. Full article
(This article belongs to the Special Issue Applications of Remote Sensing and GISs in River Basin Ecosystems)
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14 pages, 1491 KiB  
Article
A Study on Enhanced Lipid Accumulation by Cold Plasma Process in Chlorella sp.
by Mohamed Aadhil Musthak Ahamed, Navaneetha Pandiyaraj Krishnasamy, Karuppusamy Murugavel, Kannappan Arunachalam, Khamis Sulaiman AlDhafri, Arunkumar Jagadeesan, Thajuddin Nooruddin, Sang-Yul Lee and MubarakAli Davoodbasha
Water 2025, 17(13), 2030; https://doi.org/10.3390/w17132030 - 6 Jul 2025
Viewed by 413
Abstract
This study investigated the enhancement in lipid accumulation in Chlorella sp. using non-thermal atmospheric pressure plasma as a pretreatment strategy for the production of value-added products. The plasma treatment was optimized by varying discharge times (0–16 min) using argon gas at a flow [...] Read more.
This study investigated the enhancement in lipid accumulation in Chlorella sp. using non-thermal atmospheric pressure plasma as a pretreatment strategy for the production of value-added products. The plasma treatment was optimized by varying discharge times (0–16 min) using argon gas at a flow rate of 4 L/min. Lipid productivity was assessed through gravimetric analysis and profiling of fatty acid methyl ester using gas chromatography−mass spectrometry (GC-MS). The growth rate and pH of the treated cells were monitored. The findings demonstrated that the 4-min plasma exposure maximized the efficiency of lipid recovery, achieving a 35% of the dry cell weight and a 34.6% increase over untreated control. However, longer plasma treatment times resulted in a comparative decrease in lipid yield, as the decline is possibly due to oxidative degradation. The findings highlight the role of plasma treatment, which significantly boosts lipid yield and gives complementary optimization of downstream processes to improve biodiesel production. The accumulation of lipids in terms of size and volume in the algal cells was assessed by confocal laser scanning microscopy. The GC–MS results of the control revealed that lipids comprised primarily mixed esters such as 2H Pyran 2 carboxylic acid ethyl esters, accounting for 50.97% and 20.52% of the total peak area. In contrast, the 4-min treated sample shifted to saturated triacylglycerols (dodecanoic acid, 2,3 propanetriyl ester), comprising 85% of the total lipid content, which efficiently produced biodiesel. Thus, the non-thermal plasma-based enhancement of lipids in the algal cells has been achieved. Full article
(This article belongs to the Special Issue Aquatic Environment and Ecosystems)
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30 pages, 5958 KiB  
Article
Forecasting Channel Morphodynamics in the Ulken Almaty River (Ile Alatau, Kazakhstan)
by Ainur Mussina, Marzhan Tursyngali, Kassym Duskayev, Javier Rodrigo-Ilarri, María-Elena Rodrigo-Clavero and Assel Abdullayeva
Water 2025, 17(13), 2029; https://doi.org/10.3390/w17132029 - 6 Jul 2025
Viewed by 378
Abstract
This article focuses on forecasting morphological changes in small rivers, using the Ulken Almaty River, located on the northern slope of the Ile Alatau range in the Tien Shan mountain system, as a case study. One of the key components of river morphology [...] Read more.
This article focuses on forecasting morphological changes in small rivers, using the Ulken Almaty River, located on the northern slope of the Ile Alatau range in the Tien Shan mountain system, as a case study. One of the key components of river morphology is the dynamics of channel processes, including erosion, accretion, and the shifting of channel forms. Understanding these processes in rivers flowing through urbanized areas is essential for mitigating environmental and infrastructural risks. Despite their importance, studies of this nature in Kazakhstan remain at a formative stage and are largely fragmentary, underscoring the need for modern approaches to river morphology analysis. Three representative sections of the Ulken Almaty River (upstream, midstream, and downstream) were selected for analysis. Satellite imagery from 2012 to 2021 was used for manual digitisation of river channel outlines. Annual erosion and accretion areas were calculated based on these data. The DSAS 5.1 module, integrated into ArcGIS 10.8.1, was applied to determine the rates of erosion and accretion over the ten-year period. To forecast future channel changes, the Kalman filter model was employed, enabling projections for 10 and 20 years into the future. A comparative analysis of the intensity of the erosion and accretion processes was conducted for each river section. Spatial and temporal variations in bank dynamics were identified, with the most significant changes occurring in the middle and lower reaches. Forecasted scenarios indicate the possible deformation pathways of the river channel influenced by both natural and anthropogenic factors. The results provide valuable insights into the spatiotemporal dynamics of fluvial processes in small mountain rivers under the pressure of urban development and climatic variability. The methodology employed in this study offers practical applications for urban planning, river management, and the mitigation of geomorphological hazards. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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16 pages, 3808 KiB  
Article
Impact of Data Quality on CNN-Based Sewer Defect Detection
by Seokwoo Jang and Dooil Kim
Water 2025, 17(13), 2028; https://doi.org/10.3390/w17132028 - 6 Jul 2025
Viewed by 317
Abstract
Sewer pipelines are essential urban infrastructure that play a key role in sanitation and disaster prevention. Regular condition assessments are necessary to detect defects early and determine optimal maintenance timing. However, traditional visual inspection using closed-circuit television (CCTV) footage is time-consuming, labor-intensive, and [...] Read more.
Sewer pipelines are essential urban infrastructure that play a key role in sanitation and disaster prevention. Regular condition assessments are necessary to detect defects early and determine optimal maintenance timing. However, traditional visual inspection using closed-circuit television (CCTV) footage is time-consuming, labor-intensive, and dependent on subjective human judgment. To address these limitations, this study develops a convolutional neural network (CNN)-based sewer defect classification model and analyzes how data quality—such as mislabeled or redundant images—affects model accuracy. A large-scale public dataset of approximately 470,000 sewer images was used for training. The model was designed to classify non-defect and three major defect categories. Based on the ResNet50 architecture, the model incorporated dropout and L2 regularization to prevent overfitting. Experimental results showed the highest accuracy of 92.75% at a dropout rate of 0.2 and a regularization coefficient of 0.01. Further analysis revealed that mislabeled, redundant, or obscured images within the dataset negatively impacted model performance. Additional experiments quantified the impact of data quality on accuracy, emphasizing the importance of proper dataset curation. This study provides practical insights into optimizing data-driven approaches for automated sewer defect detection and high-performance model development. Full article
(This article belongs to the Special Issue Urban Sewer Systems: Monitoring, Modeling and Management)
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23 pages, 3761 KiB  
Article
Long-Term Changes in Groundwater Levels in the Białowieża Forest, Poland, Under Climate Change
by Andrzej Boczoń, Michał Wróbel and Anna Kowalska
Water 2025, 17(13), 2027; https://doi.org/10.3390/w17132027 - 5 Jul 2025
Viewed by 498
Abstract
Groundwater is the primary water source for ecosystems, and so changes in groundwater levels, if directional and constant, can cause changes in vegetation and habitat characters. In Białowieża National Park, a significant decline in the water table was observed at the beginning of [...] Read more.
Groundwater is the primary water source for ecosystems, and so changes in groundwater levels, if directional and constant, can cause changes in vegetation and habitat characters. In Białowieża National Park, a significant decline in the water table was observed at the beginning of the 20th century. The question therefore arose as to whether the changes that occurred at that time were permanent. A second question was whether the negative trend would continue so clearly in the following years. The study is based on measurements from 1985 to 2005 and 2022 to 2023 taken in the same monitoring wells. Complete data were collected from 21 monitoring wells. An analysis of groundwater levels between 1985 and 2005 showed an average decline of 0.08 m/10 years in swamp habitats, 0.11 m/10 years in moist habitats, and 0.21 m/10 years in fresh habitats. The measurements in 2022 and 2023 showed that the trend of falling water levels had slowed down in almost the entire study area, with water levels in recent years being similar to those at the beginning of the century. This was also confirmed by comparing years with similar precipitation: 2022 with 1986, and 2002, 2004, and 2023 with 1999. This was due to the higher precipitation after 2005. In the period of 2006–2023, precipitation in the hydrological years was on average 60 mm higher than in the period of 1985–2005. Despite the clear trend toward rising air temperatures, the higher precipitation compensated for the higher evapotranspiration. However, one area showed a systematic decrease in water levels. This occurred at the watershed of the two largest rivers in the Białowieża Forest. The findings indicate that watershed areas are most vulnerable to lowering the groundwater level due to climatic warming. Full article
(This article belongs to the Special Issue Impacts of Climate Change on Water Resources and Water Risks, 2nd Edition)
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22 pages, 2944 KiB  
Article
From Wastewater to Soil Amendment: A Case Study on Sewage Sludge Composting and the Agricultural Application of the Compost
by Csilla Almási, Zoltán Veres, Ibolya Demeter, Viktória Orosz, Tímea Tóth, Mostafa M. Mansour, István Henzsel, Zsolt Bogdányi, Tamás András Szegi and Marianna Makádi
Water 2025, 17(13), 2026; https://doi.org/10.3390/w17132026 - 5 Jul 2025
Viewed by 456
Abstract
The treatment of wastewater and the utilization of the by-products of these processes are an important part of the circular economy. The sewage sludge, a result of wastewater treatment, could be used as a material for plant nutrient supply and/or soil-improving products. The [...] Read more.
The treatment of wastewater and the utilization of the by-products of these processes are an important part of the circular economy. The sewage sludge, a result of wastewater treatment, could be used as a material for plant nutrient supply and/or soil-improving products. The city of Nyíregyháza, Hungary, with 120,000 citizens, has a well-planned water treatment plant operated by Nyírségvíz Ltd., which, in cooperation with the Research Institute of Nyíregyháza, developed a municipal sewage sludge compost (SSC). The closed loop of sewage water treatment and the agricultural utilization of its by-product has been developed and managed. The compost product called Nyírkomposzt was planned for acidic sandy soils. Beyond the agronomic benefits, the sustainable and environmentally sound utilization of SSC reduces sewage sludge disposal. This active involvement of a water utility company demonstrates the potential of cross-sectoral cooperation in solving environmental problems. The quality of the compost fits the Hungarian legislation. To study the effects of 0, 9, 18, and 27 t ha−1 doses of compost on acidic sandy soil, a long-term small plot experiment was started in 2003. The cumulative effects of the regular (every third year, last treatment before sampling in 2021) application of the SSC showed positive changes in basic soil properties, depending on the doses used. Increasing values were found in the case of pH from 4.5 to 6, plant available P2O5 from 240 to 690 ppm, and plant available K2O from 180 to 200 ppm. The plant-available zinc and copper content also increased. Soil organic matter and total N content stabilized at around 0.9% and 0.08%, respectively. The grain yields of winter rye also increased in both investigated years. The yields of 18 t ha−1 treatment were about two times higher compared to the control, but only in 2022 was the difference significant. Our findings underscore the potential of well-planned SSC applications to improve the fertility of ploughed, acidic sandy soil, taking into account the theory of the circular economy by utilizing wastes and decreasing landfilling. Full article
(This article belongs to the Special Issue Treatment and Resource Utilization of Urban Sewage Sludge)
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20 pages, 8465 KiB  
Article
Research on Urban Flood Risk Assessment Based on Improved Structural Equation Modeling (ISEM) and the Extensible Matter-Element Analysis Method (EMAM)
by Lin Yan, Lihong Zhang, Weichao Yang, Caixia Chen, Jianxin Lin, Zhenxian Chen, Xuefeng Jiang, Haoyang Liang, Peijiang Cong, Jinhua Gao and Tuo Xue
Water 2025, 17(13), 2025; https://doi.org/10.3390/w17132025 - 5 Jul 2025
Viewed by 305
Abstract
With the rapid development of the global economy, urban flood events are occurring more frequently. Scientific risk assessment methods are of great significance in reducing the loss of life and property. This study is devoted to developing an integrated urban flood risk assessment [...] Read more.
With the rapid development of the global economy, urban flood events are occurring more frequently. Scientific risk assessment methods are of great significance in reducing the loss of life and property. This study is devoted to developing an integrated urban flood risk assessment approach based on improved structural equation modeling and the extensible matter-element analysis method. Firstly, a flood risk assessment index system containing four dimensions (hazard, exposure, vulnerability, and regional shelter capability) is established according to a hydrological–hydrodynamic model and a literature survey. Subsequently, improved structural equation modeling (ISEM) coupled with Pearson’s correlation coefficient is introduced to determine indicator weights while eliminating correlations among indicator variables, thereby enhancing the accuracy of the weight calculation. Finally, the extensible matter-element evaluation analysis method (EMAM) is employed to conduct the urban flood risk assessment, providing a more scientific evaluation of urban flood risks through the calculation results of the correlation degree between index factors and risk levels. The integrated flood risk assessment approach was applied in the Liwan District in Guangzhou City, China, and the results demonstrated that the novel approach effectively enhances the accuracy of urban flood risk assessment by 23.69%. In conclusion, this research offers a novel and high-precision methodology for risk assessment, contributing to decision-making in disaster prevention and control. Full article
(This article belongs to the Special Issue Urban Flood Mitigation and Sustainable Stormwater Management—2nd Edition)
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20 pages, 3364 KiB  
Article
Improved Groundwater Arsenic Contamination Modeling Using 3-D Stratigraphic Mapping, Eastern Wisconsin, USA
by Eric D. Stewart, William A. Fitzpatrick and Esther K. Stewart
Water 2025, 17(13), 2024; https://doi.org/10.3390/w17132024 - 5 Jul 2025
Viewed by 229
Abstract
Dissolved arsenic in private bedrock drinking water wells is a problem in eastern Wisconsin. Previous studies have identified bedrock sources of arsenic as discrete intervals within the local Paleozoic sedimentary section and have also identified release mechanisms causing arsenic to enter well boreholes. [...] Read more.
Dissolved arsenic in private bedrock drinking water wells is a problem in eastern Wisconsin. Previous studies have identified bedrock sources of arsenic as discrete intervals within the local Paleozoic sedimentary section and have also identified release mechanisms causing arsenic to enter well boreholes. However, widespread contamination modeling is hindered by a lack of 3-D knowledge constraining the depth of the arsenic-bearing units in the subsurface. The growth and improvement of 3-D geologic mapping provides an opportunity to improve predictive models. This study in eastern Wisconsin, USA, uses a multivariate binary logistic regression analysis combined with 3-D geologic mapping to both assess various geologic and well construction factors that impact arsenic occurrence, and improve the ability to predict contamination risk. We find well construction characteristics, the stratigraphic unit within the open interval of a well, and the proximity to fold axes/fault zones are all statistically significant variables that impact the probability of a well exceeding either 2 or 10 µg/L dissolved arsenic. We apply these results by using 3-D mapping to determine the geologic unit present within the open interval of thousands of untested wells and use the logistic regression results to calculate contamination probability. This allows arsenic risk to be rapidly estimated for thousands of individual groundwater wells, and models of potential casing regulations to be assessed. Full article
(This article belongs to the Section Water Quality and Contamination)
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28 pages, 12839 KiB  
Systematic Review
A Review of Flood Mitigation Performance and Numerical Representation of Leaky Barriers
by Wuyi Zhuang, Jun Ma, Rupal Mandania and Jack Chen
Water 2025, 17(13), 2023; https://doi.org/10.3390/w17132023 - 5 Jul 2025
Viewed by 410
Abstract
Leaky barriers mimic the natural accumulation of large wood in watercourses to effectively slow and store runoff and flow. Their role in flood management has attracted increasing attention due to their potential to reduce downstream risk. Numerous field studies have demonstrated the effectiveness [...] Read more.
Leaky barriers mimic the natural accumulation of large wood in watercourses to effectively slow and store runoff and flow. Their role in flood management has attracted increasing attention due to their potential to reduce downstream risk. Numerous field studies have demonstrated the effectiveness of leaky barriers in retaining flood water in upstream catchment. However, their hydraulic behaviour remains poorly quantified due to limited empirical data and the modelling challenges. This review systematically investigates and synthesises research conducted over the past five years on the hydraulic behaviour and numerical representation of leaky barriers, while also drawing on earlier relevant studies to provide broader context. Additionally, it summarizes key hydraulic parameters, empirical equations, and modelling approaches that are used to characterise these structures. Furthermore, this review highlights the challenges of modelling individual leaky barriers in the field, which complicate their structural design and implementation. Future research should investigate the long-term performance of leaky barriers and explore optimal placement strategies to enhance flood mitigation within a catchment. Full article
(This article belongs to the Special Issue Computer Modelling Techniques in Environmental Hydraulics and Water Resource Engineering)
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22 pages, 1782 KiB  
Article
What Are the Key Factors Influencing the Water Price in Interbasin Water Transfer Projects? An Integrated Fuzzy Decision-Making Trial and Evaluation Laboratory (DEMATEL)–Interpretive Structural Model (ISM)–Grey Relational Analysis (GRA) Method
by Jiangrui Wang, Jiwei Zhu, Jiawei Shi and Siqi Wang
Water 2025, 17(13), 2022; https://doi.org/10.3390/w17132022 - 5 Jul 2025
Viewed by 344
Abstract
A reasonable water price for interbasin water transfer projects (IWTPs) is vital for solving the problem of unequal water use among different water users caused by different water source supply prices, promoting external water transfer consumption, and ensuring the stable and equitable project [...] Read more.
A reasonable water price for interbasin water transfer projects (IWTPs) is vital for solving the problem of unequal water use among different water users caused by different water source supply prices, promoting external water transfer consumption, and ensuring the stable and equitable project operation. However, the formulation of the water price is influenced by many factors, and it is necessary to identify the key factors and their interactions in the water prices formulation for IWTPs. In this study, we identified 15 factors that affect it. This paper used the fuzzy decision-making trial and evaluation laboratory (DEMATEL) to analyze the causal relationships and importance levels among the influencing factors. A four-level hierarchical structural model was established using an interpretive structural model (ISM), which intuitively displayed the hierarchical structure and pathways of each factor. The role of each influencing factor was determined by using MICMAC. Finally, the grey relational analysis method was used to identify the top five key factors: the socioeconomic development level, diversification of water resources, water demand of water users, cost of the project’s water supply, and national policies and regulations. Strategies to improve the formulation of water prices have also been proposed. The results show that the top five factors influencing the water price for IWTPs are the socio-economic development level, diversification of water resources, water demand of water users, cost of the project’s water supply, and national policies and regulations. The water price should be formulated based on the water resource cost, supply–demand relationships of water resources, and policy objectives to ensure scientific and reasonable cost allocation and differentiated pricing. For water-transfer projects with strong public welfare, the government may lower water prices through financial subsidies to alleviate the burden on water users. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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32 pages, 24319 KiB  
Article
Long-Term Water Level Projections for Lake Balkhash Using Scenario-Based Water Balance Modeling Under Climate and Socioeconomic Uncertainties
by Sayat Alimkulov, Lyazzat Makhmudova, Elmira Talipova, Gaukhar Baspakova, Akhan Myrzakhmetov, Zhanibek Smagulov and Alfiya Zagidullina
Water 2025, 17(13), 2021; https://doi.org/10.3390/w17132021 - 4 Jul 2025
Viewed by 310
Abstract
The study presents a scenario analysis of the long-term dynamics of the water level of Lake Balkhash, one of the largest closed lakes in Central Asia, taking into account climate change according to CMIP6 scenarios (SSP2-4.5 and SSP5-8.5) and socio-economic factors of water [...] Read more.
The study presents a scenario analysis of the long-term dynamics of the water level of Lake Balkhash, one of the largest closed lakes in Central Asia, taking into account climate change according to CMIP6 scenarios (SSP2-4.5 and SSP5-8.5) and socio-economic factors of water use. Based on historical data (1947–2021) and a water balance model, the contribution of surface runoff, precipitation and evaporation to the formation of the lake’s hydrological regime was assessed. It was established that the main source of water resources for the lake is the flow of the Ile River, which feeds the western part of the reservoir. The eastern part is characterized by extremely limited water inflow, while evaporation remains the main element of water consumption, having increased significantly in recent decades due to rising air temperatures. Increasing intra-seasonal and interannual fluctuations in water levels have been recorded: The amplitude of short-term fluctuations reached 0.7–0.8 m, which exceeds previously characteristic values. The results of water balance modeling up to 2050 show a trend towards a 30% reduction in surface inflow and an increase in evaporation by 25% compared to the 1981–2010 climate norm, which highlights the high sensitivity of the lake’s hydrological regime to climatic and anthropogenic influences. The results obtained justify the need for the comprehensive and adaptive management of water resources in the Balkhash Lake basin, taking into account the transboundary nature of water use and changing climatic conditions. Full article
(This article belongs to the Special Issue Advance in Hydrology and Hydraulics of the River System Research 2025)
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17 pages, 2885 KiB  
Article
Research on Construction and Application of Water Processes Based on Knowledge Graph: Analysis of Dynamic Paths and Impact Factors
by Yanhong Song, Ping Ai, Chuansheng Xiong, Jintao Li and Shicheng Gong
Water 2025, 17(13), 2020; https://doi.org/10.3390/w17132020 - 4 Jul 2025
Viewed by 213
Abstract
The water process refers to the movement and changes in water on Earth, encompassing changes among its three states and its spatial movement. This process is vital for human society as it directly influences water resources, environmental sustainability, and climate regulation. Previous studies [...] Read more.
The water process refers to the movement and changes in water on Earth, encompassing changes among its three states and its spatial movement. This process is vital for human society as it directly influences water resources, environmental sustainability, and climate regulation. Previous studies have used various related factors to analyze the water process but have not explained the rationale behind selecting these factors from the perspective of pathways. Based on this, the paper explores the construction and application of a top-down water process knowledge graph to clarify the changing process of water movement and the sources of influencing factors. Firstly, we define the concept of the water process and classify its entities based on the concept of water boundaries. Secondly, we identify key knowledge components of the water process, including water bodies, processes, and influencing factors. Finally, we construct and analyze a knowledge graph of the water process and its influencing factors. Results show that (1) the paths of water process help us understand the movement and change process of the water bodies; (2) the number of paths increases with the length of the connection between entities, reflecting the complexity of water process relationships; and (3) tracing these pathways can help identify their influencing factors, providing a data foundation for applying deep learning algorithms in water process research. Full article
(This article belongs to the Section Hydrology)
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12 pages, 2381 KiB  
Article
Correlating Parameters Evaluating Sludge Dewaterability and Morphological Characteristics of Sludge Flocs by a Commercial Smartphone and Image Analysis
by Yuyan Lin, Zijun Xu, Yizhang Jiang, Yue Jiang and Keke Xiao
Water 2025, 17(13), 2019; https://doi.org/10.3390/w17132019 - 4 Jul 2025
Viewed by 205
Abstract
Due to the lack of sophisticated instruments for monitoring sludge dewatering performance in certain wastewater treatment plants, there is an urgent need to develop cost-effective and rapidly deployable technologies for assessing sludge dewaterability. This study proposed an image-based approach to evaluate sludge dewaterability. [...] Read more.
Due to the lack of sophisticated instruments for monitoring sludge dewatering performance in certain wastewater treatment plants, there is an urgent need to develop cost-effective and rapidly deployable technologies for assessing sludge dewaterability. This study proposed an image-based approach to evaluate sludge dewaterability. Flocculation images of sludge were captured using a smartphone under controlled conditions and processed via MATLAB for grayscale adjustment, contrast enhancement, and size standardization. Fractal image analysis was employed to justify the selection of floc area (rather than floc equivalent diameter) for downstream analyses. Significant correlations were observed between the number of different sludge floc area range and key dewaterability parameters: The number of flocs in area range of 10−6–10−5 cm2 showed a negative correlation with capillary suction time (CST) (regression coefficient (R) = −0.511, probability (p) < 0.05) and a positive correlation with median particle size (R = 0.470, p < 0.05); the number of flocs in area range of 10−5–10−4 cm2 exhibited a stronger negative correlation with CST (R = −0.538, p < 0.05) and a positive correlation with median particle size (R = 0.480, p < 0.05). Further validation experiments using a laboratory-scale diaphragm filter press demonstrated that when the proportion of the number of flocs in area range of 10−5–10−4 cm2 relative to the total number of flocs for conditioned sludge fell below 70%, the dewatered sludge cake achieved a water content of less than 60%. This study highlights the feasibility of using commercially available smartphones as a practical tool for evaluating sludge dewaterability. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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23 pages, 24393 KiB  
Article
Integrating Urban Planning and Hydraulic Engineering: Nature-Based Solutions for Flood Mitigation in Tainan City
by Wei-Cheng Lo, Meng-Hsuan Wu, Jie-Ying Wu and Yao-Sheng Huang
Water 2025, 17(13), 2018; https://doi.org/10.3390/w17132018 - 4 Jul 2025
Viewed by 318
Abstract
Extreme rainfall events driven by climate change are increasing flood risks. Addressing flood mitigation solely from either a hydraulic engineering or urban planning perspective may overlook both feasibility and effectiveness. This study focuses on Tainan City and the Tainan Science Park in Taiwan, [...] Read more.
Extreme rainfall events driven by climate change are increasing flood risks. Addressing flood mitigation solely from either a hydraulic engineering or urban planning perspective may overlook both feasibility and effectiveness. This study focuses on Tainan City and the Tainan Science Park in Taiwan, applying the NbS framework to assess flood mitigation strategies. From an urban planning perspective, Agricultural Development Zone Type II (Agri-DZII), parks, green spaces, and Taiwan Sugar Corporation (TSC) land were selected as flood detention sites. Hydraulic modeling was used to evaluate their effectiveness under both current and climate-change-induced rainfall conditions. Simulation results show that under current rainfall conditions, flood mitigation measures reduced inundated areas with depths exceeding 2.0 m by up to 7.8% citywide and 20.8% within the Tainan Science Park Special District Plan Area. However, under climate change scenarios, the reduction effects declined significantly, with maximum reductions of only 1.6% and 17.8%, respectively. Results indicate that, even when utilizing all available detention areas, the overall flood reduction in Tainan City remains limited. However, TSC agri-land within the Tainan Science Park overlaps with high-flood-risk zones, demonstrating significant local flood mitigation potential. This study recommends integrating hydrological analysis into urban planning to prevent high-density residential and economic zones from being designated in flood-prone areas. Additionally, policymakers should consider reserving appropriate land for flood detention to enhance climate resilience. By combining urban planning and hydraulic engineering perspectives, this study highlights the flexibility of NbS in disaster management, advocating for the integration of Natural Water Detention Measures into flood adaptation strategies to improve urban water management and climate adaptability. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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18 pages, 5272 KiB  
Article
Twin-Peaks Streamflow Timing: Can We Use Forest and Alpine Snow Melt-Out Response to Estimate?
by Lenka G. Doskocil, Steven R. Fassnacht, David M. Barnard, Anna K. D. Pfohl, Jeffrey E. Derry and William E. Sanford
Water 2025, 17(13), 2017; https://doi.org/10.3390/w17132017 - 4 Jul 2025
Viewed by 297
Abstract
Snow-dominated watersheds experience a snowmelt-driven peak in streamflow that occurs in the spring or early summer. Some of the headwater basins in Colorado, USA have two or more peaks in streamflow, including the Uncompahgre River, a Colorado River tributary. The timing of peak [...] Read more.
Snow-dominated watersheds experience a snowmelt-driven peak in streamflow that occurs in the spring or early summer. Some of the headwater basins in Colorado, USA have two or more peaks in streamflow, including the Uncompahgre River, a Colorado River tributary. The timing of peak streamflow is important for water management and recreational planning. As such, we examined the connection between the timing of each streamflow peak and readily available snow measurement information in the forest and alpine zones. These station data are the date of the initiation of snowmelt, 50% melt-out, and complete melt-out or the snow disappearance date (SDD). When it occurs before mid-June (14 of 20 years), the timing of the first peak is well correlated with the forested snow measurement station SDD. The second streamflow peak timing is well correlated with SDD from the alpine station except for very early (3 years) and very late (2 years) SDD. We also examine the spatial variability of snow disappearance and peak snow water equivalent (SWE) across the four seasonally snow-covered headwater sub-basins using a dataset from a coupled meteorological–snowpack model. Full article
(This article belongs to the Special Issue Advance in Hydrology and Hydraulics of the River System Research 2025)
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33 pages, 25988 KiB  
Article
Erosion Resistance Assessment of Grass-Covered Embankments: Insights from In Situ Overflow Tests at the Living Lab Hedwige-Prosper Polder
by Davy Depreiter, Jeroen Vercruysse, Kristof Verelst and Patrik Peeters
Water 2025, 17(13), 2016; https://doi.org/10.3390/w17132016 - 4 Jul 2025
Viewed by 206
Abstract
Grass-covered levees commonly protect river and estuarine areas against flooding. Climate-induced water level changes may increasingly expose these levees to overflow events. This study investigates whether grass-covered levees can withstand such events, and under what conditions failure may occur. Between 2020 and 2022, [...] Read more.
Grass-covered levees commonly protect river and estuarine areas against flooding. Climate-induced water level changes may increasingly expose these levees to overflow events. This study investigates whether grass-covered levees can withstand such events, and under what conditions failure may occur. Between 2020 and 2022, full-scale overflow tests were conducted at the Living Lab Hedwige-Prosperpolder along the Dutch–Belgian Scheldt Estuary to assess erosion resistance under varying hydraulic conditions and vegetation states. A custom-built overflow generator was used, with instrumentation capturing flow velocity, water levels, and erosion progression. The results show that well-maintained levees with intact grass cover endured overflow durations up to 30 h despite high terminal flow velocities (4.9–7.7 m/s), without structural damage. In contrast, levee sections with pre-existing surface anomalies, such as animal burrows, slope irregularities, surface damage, or reed-covered soft soils, failed rapidly, often within one to two hours. Animal burrows facilitated subsurface flow and internal erosion, initiating fast, retrograde failure. These findings highlight the importance of preventive maintenance, particularly the timely detection and repair of anomalies. Once slope failure begins, the process unfolds rapidly, leaving no practical window for intervention. Full article
(This article belongs to the Special Issue Slope Stability Analyses and Landslide Risk Assessment Under Hydrodynamic Action)
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20 pages, 6528 KiB  
Article
Runoff Evolution Characteristics and Predictive Analysis of Chushandian Reservoir
by Jian Qi, Dongyang Ma, Zhikun Chen, Qingqing Tian, Yu Tian, Zhongkun He, Qianfang Ma, Yunfei Ma and Lei Guo
Water 2025, 17(13), 2015; https://doi.org/10.3390/w17132015 - 4 Jul 2025
Viewed by 262
Abstract
The Chushandian Reservoir, a key control project on the Huaihe River, is vital for flood control, water allocation, and maintaining ecological baseflow. This study analyzes runoff evolution and provides predictive insights for sustainable water management. Methods employed include Extremum Symmetric Mode Decomposition (ESMD) [...] Read more.
The Chushandian Reservoir, a key control project on the Huaihe River, is vital for flood control, water allocation, and maintaining ecological baseflow. This study analyzes runoff evolution and provides predictive insights for sustainable water management. Methods employed include Extremum Symmetric Mode Decomposition (ESMD) for decomposing complex signals, a mutation detection algorithm to identify significant changes in time-series data, and cross-wavelet transform to examine correlations and phase relationships between time series across frequencies. Additionally, the hybrid models GM-BP and CNN-LSTM were used for runoff forecasting. Results show cyclical fluctuations in annual runoff every 2.3, 5.3, and 14.5 years, with a significant decrease observed in 2010. Among climate factors, the Atlantic Multidecadal Oscillation (AMO) had the strongest correlation with runoff variability, while ENSO and PDO showed more localized impacts. Model evaluations indicated strong predictive performance, with Nash–Sutcliffe Efficiency (NSE) scores of 0.884 for GM-BP and 0.909 for CNN-LSTM. These findings clarify the climatic drivers of runoff variability and provide valuable tools for water resource management at the Chushandian Reservoir under future climate uncertainties. Full article
(This article belongs to the Section Hydrology)
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23 pages, 3316 KiB  
Article
Water–Climate Nexus: Exploring Water (In)security Risk and Climate Change Preparedness in Semi-Arid Northwestern Ghana
by Cornelius K. A. Pienaah, Mildred Naamwintome Molle, Kristonyo Blemayi-Honya, Yihan Wang and Isaac Luginaah
Water 2025, 17(13), 2014; https://doi.org/10.3390/w17132014 - 4 Jul 2025
Viewed by 401
Abstract
Water insecurity, intensified by climate change, presents a significant challenge globally, especially in arid and semi-arid regions of Africa. In northern Ghana, where agriculture heavily depends on seasonal rainfall, prolonged dry seasons exacerbate water and food insecurity. Despite efforts to improve water access, [...] Read more.
Water insecurity, intensified by climate change, presents a significant challenge globally, especially in arid and semi-arid regions of Africa. In northern Ghana, where agriculture heavily depends on seasonal rainfall, prolonged dry seasons exacerbate water and food insecurity. Despite efforts to improve water access, there is limited understanding of how climate change preparedness affects water insecurity risk in rural contexts. This study investigates the relationship between climate preparedness and water insecurity in semi-arid northwestern Ghana. Grounded in the Sustainable Livelihoods Framework, data was collected through a cross-sectional survey of 517 smallholder households. Nested ordered logistic regression was used to analyze how preparedness measures and related socio-environmental factors influence severe water insecurity. The findings reveal that higher levels of climate change preparedness significantly reduce water insecurity risk at individual [odds ratio (OR) = 0.35, p < 0.001], household (OR = 0.037, p < 0.001), and community (OR = 0.103, p < 0.01) levels. In contrast, longer round-trip water-fetching times (OR = 1.036, p < 0.001), water-fetching injuries (OR = 1.054, p < 0.01), reliance on water borrowing (OR = 1.310, p < 0.01), untreated water use (OR = 2.919, p < 0.001), and exposure to climatic stressors like droughts (OR = 1.086, p < 0.001) and floods (OR = 1.196, p < 0.01) significantly increase insecurity. Community interventions, such as early warning systems (OR = 0.218, p < 0.001) and access to climate knowledge (OR = 0.228, p < 0.001), and long-term residency further reduce water insecurity risk. These results underscore the importance of integrating climate preparedness into rural water management strategies to enhance resilience in climate-vulnerable regions. Full article
(This article belongs to the Special Issue Human–Water Interactions: Water Supply, Livelihood and Rural Society)
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24 pages, 1372 KiB  
Review
Research Overview on Isolated Wetlands
by Yingpu Wang, Mingjie Zhao, Wenhan Pei, Qiang Guan, Jiafu Liu, Yanhui Chen, Jiping Liu and Qiyue Zhang
Water 2025, 17(13), 2013; https://doi.org/10.3390/w17132013 - 4 Jul 2025
Viewed by 348
Abstract
Isolated wetlands, as a unique type of wetland, play a key ecological role in hydrological regulation, carbon storage, and biodiversity conservation. Although many studies have been conducted on the monitoring and ecological function assessment of isolated wetlands, a comprehensive and critical review is [...] Read more.
Isolated wetlands, as a unique type of wetland, play a key ecological role in hydrological regulation, carbon storage, and biodiversity conservation. Although many studies have been conducted on the monitoring and ecological function assessment of isolated wetlands, a comprehensive and critical review is still lacking. Through a systematic analysis of the literature from the past two decades, we found despite the large number of existing studies on isolated wetlands, direct comparison between them is often difficult due to differences in definitions. Second, human activities and climate change are the primary factors affecting wetland hydrology and leading to wetland isolation in the short term. Third, remote sensing and landscape models serve as basic tools for monitoring and analyzing isolated wetlands, but the low temporal and spatial accuracy of relevant data, along with the short research time spans, limit in-depth studies. Finally, isolated wetlands have multiple ecological functions that exhibit spatial heterogeneity and change over time. In summary, isolated wetlands have indispensable ecological functions that are currently underestimated. It is necessary to scientifically define the concept of isolated wetlands, improve the capability and accuracy of long-term dynamic monitoring, and conduct multi-functional coupling research in the future. Additionally, when formulating future wetland protection and management strategies, attention should be paid to isolated wetlands, and the temporal and spatial differences in their ecological benefits should be considered. Full article
(This article belongs to the Section Ecohydrology)
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20 pages, 4992 KiB  
Article
Spatial Heterogeneity and Controlling Factors of Heavy Metals in Groundwater in a Typical Industrial Area in Southern China
by Jiaxu Du, Fu Liao, Ziwen Zhang, Aoao Du and Jiale Qian
Water 2025, 17(13), 2012; https://doi.org/10.3390/w17132012 - 4 Jul 2025
Viewed by 514
Abstract
Heavy metal contamination in groundwater has emerged as a significant environmental issue, driven by rapid industrialization and intensified human activities, particularly in southern China. Heavy metal pollution in groundwater often presents complex spatial patterns and multiple sources; understanding the spatial heterogeneity and controlling [...] Read more.
Heavy metal contamination in groundwater has emerged as a significant environmental issue, driven by rapid industrialization and intensified human activities, particularly in southern China. Heavy metal pollution in groundwater often presents complex spatial patterns and multiple sources; understanding the spatial heterogeneity and controlling factors of heavy metals is crucial for pollution prevention and water resource management in industrial regions. This study applied spatial autocorrelation analysis and self-organizing maps (SOM) coupled with K-means clustering to investigate the spatial distribution and key influencing factors of nine heavy metals (Cr, Fe, Mn, Ni, Cu, Zn, As, Ba, and Pb) in a typical industrial area in southern China. Heavy metals show significant spatial heterogeneity in concentrations. Cr, Mn, Fe, and Cu form local hotspots near urban and peripheral zones; Ni and As present downstream enrichment along the river pathway with longitudinal increase trends; Zn, Ba, and Pb exhibit a fluctuating pattern from west to east in the piedmont region. Local Moran’s I analysis further revealed spatial clustering in the northwest, riverine zones, and coastal outlet areas, providing insight into potential source regions. SOM clustering identified three types of groundwater: Cluster 1 (characterized by Cr, Mn, Fe, and Ni) is primarily influenced by industrial pollution and present spatially scattered distribution; Cluster 2 (dominated by As, NO3−, Ca2+, and K+) is associated with domestic sewage and distributes following river flow; Cluster 3 (enriched in Zn, Ba, Pb, and NO3−) is shaped by agricultural activities and natural mineral dissolution, with a lateral distribution along the piedmont zone. The findings of this study provide a scientific foundation for groundwater pollution prevention and environmental management in industrialized areas. Full article
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25 pages, 3133 KiB  
Article
Wastewater Impact on Surface Water Quality and Suitability of Water Reuse in Agriculture Using a Comprehensive Methodology Based on PCA and Specific Indices
by Iulia Ajtai, Anda Anton, Carmen Roba, Camelia Botezan, Ioana Piștea, Marius Oprea and Călin Baciu
Water 2025, 17(13), 2011; https://doi.org/10.3390/w17132011 - 4 Jul 2025
Viewed by 324
Abstract
Effluents from wastewater treatment plants (WWTPs) represent a potential pollution risk to surface waters. Moreover, the growing practice of using treated wastewater for irrigation has recently received increased attention in terms of its suitability, raising concerns about its impact on soil health, agricultural [...] Read more.
Effluents from wastewater treatment plants (WWTPs) represent a potential pollution risk to surface waters. Moreover, the growing practice of using treated wastewater for irrigation has recently received increased attention in terms of its suitability, raising concerns about its impact on soil health, agricultural productivity, and human well-being. The aim of this study is to apply a comprehensive approach to assess the impact of wastewater from a Romanian WWTP on surface water quality and its suitability for irrigation practices. For this purpose, a set of physico-chemical parameters were analyzed, and a Water Quality Index (WQI) was developed based on Principal Component Analysis (PCA). The irrigation suitability of the effluent was further assessed using key parameters (electrical conductivity—EC; total dissolved solids—TDSs; turbidity; Biochemical Oxygen Demand—BOD5) and specific irrigation indices (Sodium Adsorption Ratio—SAR; Permeability Index—PI; Residual Sodium Carbonate—RSC; Sodium percentage—%Na; Kelly’s ratio—KR). The results for the surface water quality indicated high contents of Na+ (10.2–42.5 mg/L), Cl− (11.9–48.4 mg/L), and SO42− (10.7–68.5 mg/L) downstream of the wastewater discharge point. The WQI, which reflects overall water quality for environmental health, showed excellent water quality, with a mean of 34 upstream and 47 downstream, suggesting the potential impact of treated wastewater discharge downstream. However, the irrigation indices revealed elevated sodium levels in the effluent, with %Na (up to 86%) categorizing 70% of the samples as unsuitable, while KR (up to 6.2) classified all samples as unsuitable. These findings suggest that despite a low impact on the river water, elevated sodium levels in effluent may limit suitability for irrigation, highlighting the importance of monitoring effluent water reuse. Full article
(This article belongs to the Special Issue Ecological Wastewater Treatment and Resource Utilization)
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