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Particulate and Dissolved Metals in the Pearl River Estuary, China—Part 1: Spatial Distributions and Influencing Factors
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Assessing the Relationship Between Groundwater Availability, Access, and Contamination Risk in Arizona’s Drinking Water Sources
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Predicting Surface Stokes Drift with Deep Learning
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Flood Susceptibility Analysis with Integrated Geographic Information System and Analytical Hierarchy Process
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Macrophytes and Phytoplankton, Two Primary Antithetical Producers in Degraded Water Systems
Journal Description
Water
Water
is a peer-reviewed, open access journal on water science and technology, including the ecology and management of water resources, and is published semimonthly online by MDPI. Water collaborates with the Stockholm International Water Institute (SIWI). In addition, the American Institute of Hydrology (AIH), The Polish Limnological Society (PLS) and Japanese Society of Physical Hydrology (JSPH) are affiliated with Water and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Ei Compendex, GEOBASE, GeoRef, PubAg, AGRIS, CAPlus / SciFinder, Inspec, and other databases.
- Journal Rank: JCR - Q2 (Water Resources) / CiteScore - Q1 (Water Science and Technology)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 17.5 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journals for Water include: GeoHazards.
Impact Factor:
3.0 (2023);
5-Year Impact Factor:
3.3 (2023)
Latest Articles
Pollutant Monitoring Solutions in Water and Sewerage Networks: A Scoping Review
Water 2025, 17(10), 1423; https://doi.org/10.3390/w17101423 (registering DOI) - 9 May 2025
Abstract
Ensuring water quality standards in water and wastewater distribution systems is crucial to protect public health and ecosystems. Environmental monitoring technologies have evolved rapidly owing to the use of portable devices and digital platforms. The integration of digital sensors, Internet of Things (IoT)
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Ensuring water quality standards in water and wastewater distribution systems is crucial to protect public health and ecosystems. Environmental monitoring technologies have evolved rapidly owing to the use of portable devices and digital platforms. The integration of digital sensors, Internet of Things (IoT) systems, and technologies such as Arduino and Raspberry Pi enables real-time monitoring of emerging contaminants (CECs) in water and wastewater networks, overcoming the limitations of traditional methods. This review provides an overview of integrated systems based on lab-on-a-chip, Raman spectrometry, and colourimetry for pollutant detection in water and wastewater networks. Our comparative analysis highlights that lab-on-a-chip devices enhance analytical efficiency (achieving detection limits in the sub-ppb range for certain heavy metals), Raman spectrometry—especially SERS—provides ultra-trace sensitivity and molecular specificity, and colorimetric sensors offer cost-effective, rapid field deployment albeit with moderate sensitivity. The novelty of this work lies in integrating these findings to illustrate how IoT-enabled sensor platforms can complement traditional methods for real-time water quality monitoring. The PRISMA framework and Rayyan platform were used for systematic literature selection, analysing 72 recent references. These findings indicate that lab-on-a-chip systems enhance analytical efficiency but face selectivity and reagent stability challenges. Raman spectrometry offers high specificity but has high operational costs, while colorimetric sensors are practical for rapid field analysis. Future research should focus on optimising analytical protocols and validating them in real-world settings, as suggested by recent studies monitoring specific contaminants in different aquatic matrices.
Full article
(This article belongs to the Special Issue Urban Water Pollution Control: Theory and Technology)
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Open AccessArticle
Positive–Unlabeled Learning-Based Hybrid Models and Interpretability for Groundwater Potential Mapping in Karst Areas
by
Benteng Bi, Jingwen Li, Tianyu Luo, Bo Wang, Chen Yang and Lina Shen
Water 2025, 17(10), 1422; https://doi.org/10.3390/w17101422 (registering DOI) - 9 May 2025
Abstract
Despite the increasing adoption of machine learning and data-driven models for predicting regional groundwater potential (GWP), exploration geoscientists have recognized that these models still face various challenges in their predictive precision. For instance, the stochastic uncertainty associated with incomplete groundwater investigation inventories and
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Despite the increasing adoption of machine learning and data-driven models for predicting regional groundwater potential (GWP), exploration geoscientists have recognized that these models still face various challenges in their predictive precision. For instance, the stochastic uncertainty associated with incomplete groundwater investigation inventories and the inherent non-transparency characteristic of machine learning models, which lack transparency regarding how input features influence outcomes, pose significant challenges. This research constructs a bagging-based learning framework that integrates Positive–Unlabeled samples (BPUL), along with ex-post interpretability, to map the GWP of the Lijiang River Basin in China, a renowned karst region. For this purpose, we first aggregated various topographic, hydrological, geological, meteorological, and land conditional factors. The training samples were enhanced with data from the subterranean stream investigated in the study area, in addition to conventional groundwater inventories such as wells, boreholes, and karst springs. We employed the BPUL algorithm with four different base learners—Logistic Regression (LR), k-nearest neighbor (KNN), Random Forest (RF), and Light Gradient Boosting Machine (LightGBM)—and model validation was conducted to map the GWP in karst regions. The findings indicate that all models exhibit satisfactory performance in GWP mapping, with the hybrid ensemble models (RF-BPUL and LightGBM-BPUL) achieving higher validation scores. The model interpretation of the aggregated SHAP values revealed the contribution patterns of various conditional factors to groundwater distribution in karst zones, emphasizing that lithology, the multiresolution index of valley bottom flatness (MRVBF), and the geochemical element calcium oxide (CaO) have the most significant impact on groundwater enrichment in karst zones. These findings offer new approaches and methodologies for the in-depth exploration and scientific prediction of groundwater potential.
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(This article belongs to the Section Hydrogeology)
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Low-Carbon Hybrid Constructed Wetland System for Rural Domestic Sewage: Substrate–Plant–Microbe Synergy and Annual Performance
by
Jiawei Wang, Gang Zhang, Dejian Wang, Yuting Zhao, Lingyu Wu, Yunwen Zheng and Qin Liu
Water 2025, 17(10), 1421; https://doi.org/10.3390/w17101421 (registering DOI) - 9 May 2025
Abstract
An integrated hybrid system was developed, incorporating sedimentation, anaerobic digestion, biological filtration, and a two-stage hybrid subsurface flow constructed wetland, horizontal subsurface flow constructed wetland (HSSFCW) and vertical subsurface flow constructed wetland (VSSFCW), to treat rural sewage in southern Jiangsu. To optimize nitrogen
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An integrated hybrid system was developed, incorporating sedimentation, anaerobic digestion, biological filtration, and a two-stage hybrid subsurface flow constructed wetland, horizontal subsurface flow constructed wetland (HSSFCW) and vertical subsurface flow constructed wetland (VSSFCW), to treat rural sewage in southern Jiangsu. To optimize nitrogen and phosphorus removal, the potential of six readily accessible industrial and agricultural waste byproducts—including plastic fiber (PF), hollow brick crumbs (BC), blast furnace steel slag (BFS), a zeolite–blast furnace steel slag composite (ZBFS), zeolite (Zeo), and soil—was systematically evaluated individually as substrates in vertical subsurface flow constructed wetlands (VSSFCWs) under varying hydraulic retention times (HRTs, 0–120 h). The synergy among substrates, plants, and microbes, coupled with the effects of hydraulic retention time (HRT) on pollutant degradation performance, was clarified. Results showed BFS achieved optimal comprehensive pollutant removal efficiencies (97.1% NH4+-N, 76.6% TN, 89.7% TP, 71.0% COD) at HRT = 12 h, while zeolite excelled in NH4+-N/TP removal (99.5%/94.5%) and zeolite–BFS specializing in COD reduction (80.6%). System-wide microbial analysis revealed organic load (sludges from the sedimentation tank [ST] and anaerobic tanks [ATs]), substrate type, and rhizosphere effects critically shaped community structure, driving specialized pathways like sulfur autotrophic denitrification (Nitrospira) and iron-mediated phosphorus removal. Annual engineering validation demonstrated that the optimized strategy of “pretreatment unit for phosphorus control—vertical wetland for enhanced nitrogen removal” achieved stable effluent quality compliance with Grade 1-A standard for rural domestic sewage discharge after treatment facilities, without the addition of external carbon sources or exogenous microbial inoculants. This low-carbon operation and long-term stability position it as an alternative to energy-intensive activated sludge or membrane-based systems in resource-limited settings.
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(This article belongs to the Special Issue Constructed Wetlands: Enhancing Contaminant Removal and Remediation)
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Study on the Pollution Mechanism and Driving Factors of Groundwater Quality in Typical Industrial Areas of China
by
Li Wang, Qi Wang and Dechao Zheng
Water 2025, 17(10), 1420; https://doi.org/10.3390/w17101420 - 8 May 2025
Abstract
Uncovering the characteristics of groundwater pollution and its driving mechanisms are crucial for maintaining its ecological functions. This study focuses on hydrochemical changes and their driving factors in groundwater from different aquifers in industrial zones, taking Zibo City, Shandong Province, China, as the
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Uncovering the characteristics of groundwater pollution and its driving mechanisms are crucial for maintaining its ecological functions. This study focuses on hydrochemical changes and their driving factors in groundwater from different aquifers in industrial zones, taking Zibo City, Shandong Province, China, as the research area. During the dry and flood seasons of 2022, samples of phreatic water in pore media (17 sites) and karst confined water (23 sites) were collected and monitored. Piper trilinear diagrams, Gibbs diagrams, ion ratio diagrams, and a principal component analysis (PCA) were used for in-depth analyses. Pore phreatic water had higher excess rates of Na+, Cl−, and NO3− than karst confined water, which indicated a greater degree of human impact compared with karst confined water. The main hydrochemical type was HCO3·SO4-Ca, but in the dry season, pore phreatic water shifted to HCO3·SO4·Cl-Ca. The ion ratios and PCA indicated that the groundwater quality was mainly controlled by water–rock interactions and industrial activities. In the flood season, pore phreatic water was influenced by evaporite dissolution, industrial activities, and domestic sewage, while in the dry season, it was affected by halite and carbonate weathering dissolution and domestic sewage. Karst confined water was controlled by water–rock interactions and industrial activities in both seasons. The findings reveal that the key drivers of groundwater quality displayed significant differences depending on the aquifer type and seasonal variations. As such, customized approaches are essential to efficiently address and counteract the decline in groundwater quality.
Full article
(This article belongs to the Special Issue Pollution Mechanisms and Source Apportionment of Typical Pollutants in Aquatic Environments)
Open AccessArticle
Spatiotemporal Dynamics of Drought–Flood Abrupt Alternations and Their Delayed Effects on Vegetation Growth in Heilongjiang River Basin
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Haoyuan Ma, Jianyu Jing, Changlei Dai, Yijun Xu, Peng Qi and Hao Song
Water 2025, 17(10), 1419; https://doi.org/10.3390/w17101419 (registering DOI) - 8 May 2025
Abstract
Drought–flood abrupt alternations (DFAAs) have a greater impact on ecosystems and socioeconomic environments than lone droughts or floods. Despite the significant impact of DFAAs, research has paid little attention to their evolutionary characteristics, particularly in relation to vegetation growth in the Heilongjiang River
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Drought–flood abrupt alternations (DFAAs) have a greater impact on ecosystems and socioeconomic environments than lone droughts or floods. Despite the significant impact of DFAAs, research has paid little attention to their evolutionary characteristics, particularly in relation to vegetation growth in the Heilongjiang River Basin. Therefore, this study focuses on the Heilongjiang River Basin and employs the DFAA Index to identify and analyze abrupt alternation events from 1970 to 2019. It also examines the annual and interannual distributions of vegetation growth changes from 2000 to 2019, based on the Normalized Difference Vegetation Index. Lastly, it utilizes correlation analysis to investigate the responsive relationship between vegetation growth and DFAA events. The results indicate the following: (1) Within the Heilongjiang River Basin, the number of drought-to-flood events increased over time, whereas the number of flood-to-drought events decreased over time. The frequency of mutation was relatively high in the northern region, low in the eastern region, elevated in spring and summer, and reduced in winter. (2) The Normalized Difference Vegetation Index was lowest in January, highest in July, and approximately 0 during the winter. The vegetation coverage reached its peak during the summer. (3) Vegetation changes in response to DFAAs exhibited a significant time lag. Vegetation changes in spring–summer lagged behind DFAA events by 3–4 months, while in summer–autumn, the lag was approximately 3 months. These results are of great significance for the early warning and prevention of DFAAs in the Heilongjiang River Basin.
Full article
(This article belongs to the Special Issue Climate Change and Hydrological Processes, 2nd Edition)
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Transforming Water Research Through Human Rights-Based Approaches: A Framework for Implementation
by
Leonie J. Pearson, Vachararutai Boontinand and Phan Thanh Thanh
Water 2025, 17(10), 1418; https://doi.org/10.3390/w17101418 - 8 May 2025
Abstract
The integration of human rights-based approaches (HRBAs) into water resource governance has gained significant momentum, particularly in regions facing complex water security challenges. It is now recognized that to address water security, we must address the human side of insecurity, and the HRBA
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The integration of human rights-based approaches (HRBAs) into water resource governance has gained significant momentum, particularly in regions facing complex water security challenges. It is now recognized that to address water security, we must address the human side of insecurity, and the HRBA endeavors to do this. Importantly, research projects are primary drivers of water management innovation. As research methodologies directly influence subsequent water management practices, the integration of HRBA in research becomes crucial for ensuring human rights considerations in future water governance. This study examines HRBA implementation in water research programs within the Mekong sub-region, where water insecurity significantly impacts local communities dependent on the Mekong River basin. Through an analysis of six research projects under the Sustainable Mekong Research Network, we assessed HRBA implementation using five dimensions: accountability, transparency, policy engagement, participation, and empowerment. Our mixed methods approach combined document analysis with semi-structured interviews. Projects revealed a spectrum of HRBA implementations from ‘thick’ to ‘thin’ applications, with political sensitivities and varying institutional capacities influencing implementation depth. This study introduces a novel framework for evaluating HRBA in water research, offering practical guidance for researchers and policymakers working in regions with complex socio-political dynamics. The resulting frameworks provide actionable tools that can be immediately applied in research design, stakeholder engagement processes, and policy development, enabling more equitable and effective water governance practices across diverse institutional contexts.
Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
Open AccessArticle
Spatio-Temporal Changes of Terrestrial Water Storage in Five Provinces of Northwest China from 2002 to 2022 and Their Driving Factors
by
Aimin Li, Zekun Wu, Meng Yin and Zhenqiang Guo
Water 2025, 17(10), 1417; https://doi.org/10.3390/w17101417 - 8 May 2025
Abstract
This study aims to explore the spatio-temporal changes in terrestrial water storage (TWS) in the five provinces of Northwest China and to assess the influences of various driving factors on the changes in TWS. Based on the Gravity Recovery and Climate Experiment (GRACE)
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This study aims to explore the spatio-temporal changes in terrestrial water storage (TWS) in the five provinces of Northwest China and to assess the influences of various driving factors on the changes in TWS. Based on the Gravity Recovery and Climate Experiment (GRACE) satellite data of the five provinces from April 2002 to December 2022, combined with datasets of various driving factors (precipitation, evapotranspiration, runoff, and anthropogenic water use) from 1980 to 2022, a trend analysis was conducted using Sen’s slope method and Mann–Kendall (M-K) tests to characterize the spatial–temporal changes in TWS. The water balance method and quantification of contribution rates were used to analyze the spatio-temporal response of the change in TWS to driving factors and the contributions of driving factors thereto. The results showed that the eastern part of the Xinjiang Uygur Autonomous Region and the northern parts of Shaanxi Province and Ningxia Hui Autonomous Region belonged to the decreasing centers of TWS, while the northern part of the Qinghai–Tibet Plateau belonged to the enriching center of TWS, with a decreasing trend at a rate of 2.86 mm/yr. Precipitation contributed positively to the change in TWS and had a high spatio-temporal response, while the other driving factors (evapotranspiration, runoff, and anthropogenic water use) all contributed negatively to certain extents. The contribution rates of precipitation, evapotranspiration, runoff, and anthropogenic water use were 0.363, −0.265, −0.258 and −0.115, respectively. The results are helpful for the scientific planning and management of water resources in Northwest China.
Full article
(This article belongs to the Special Issue Agricultural Water and Land Resources Planning and Management: Challenges and Endeavors)
Open AccessArticle
Legal Analysis of Reclaimed Wastewater Management in Indonesia: Reference to Malaysia and Singapore
by
Maskun Maskun, Rasyikah Md. Khalid, Nurul Habaib Al Mukarramah, Rafika Nurul Hamdani Ramli, Mutiah Wenda Juniar, Josse Charmario Wara Angi, Valeria Erika Sari Paliling, Alfiyah Nur Inayah Hamzah, Amalia Kadir and Muhammad Nazrul Abd Rani
Water 2025, 17(10), 1416; https://doi.org/10.3390/w17101416 (registering DOI) - 8 May 2025
Abstract
Indonesia faces a significant challenge in wastewater management, exacerbated by environmental degradation and the changing climate. This study addresses two main questions: What is the legal framework governing reclaimed wastewater management in Indonesia? How is the implementation of reclaimed wastewater management conducted in
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Indonesia faces a significant challenge in wastewater management, exacerbated by environmental degradation and the changing climate. This study addresses two main questions: What is the legal framework governing reclaimed wastewater management in Indonesia? How is the implementation of reclaimed wastewater management conducted in Indonesia? The answers to these questions guide the objectives of analyzing national and international regulations to identify barriers and proposing improvements through a normative legal analysis method with primary legal material, focusing on international, national, and local regulations regarding wastewater reclamation. The findings reveal that although Indonesia has established a legal framework for wastewater management, it lacks a clear enforcement mechanism, and its implementation is fragmented at the local level. Due to regional disparities, such policy implementation should evaluate and adopt suitable international best practices on wastewater treatment and recycling mechanisms. This study recommends policy harmonization, increased investment in infrastructure, and the adoption of best practices in sustainable wastewater management. Public awareness and private sector engagement are also essential to ensuring effective implementation and long-term sustainability.
Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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Impact of Subsurface Drainage and Biochar Amendment on the Coastal Soil–Plant System: A Case Study in Alfalfa Cultivation on Saline–Alkaline Soil
by
Jinxiu Liu, Hong Xiong, Shunshen Huang, Yaohua Li, Chengzhu Li, Qiang Li, Xiangying Zhang, Peng Cheng, Hiba Shaghaleh, Yousef Alhaj Hamoud and Qinyuan Zhu
Water 2025, 17(10), 1415; https://doi.org/10.3390/w17101415 - 8 May 2025
Abstract
Coastal saline–alkaline soils are characterized by high salinity and poor permeability. Subsurface drainage and biochar amendment are both practical methods, and their combination may overcome the limitations of individual measures and achieve rapid desalination and soil improvement. To evaluate the impact of different
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Coastal saline–alkaline soils are characterized by high salinity and poor permeability. Subsurface drainage and biochar amendment are both practical methods, and their combination may overcome the limitations of individual measures and achieve rapid desalination and soil improvement. To evaluate the impact of different subsurface drainage spacing and biochar amendment on soil properties and crop yield, the salt-tolerant plant “alfalfa” was used as the main material. We designed four drainage spacing treatments (0 m (CK), 6 m (S1), 12 m (S2), and 18 m (S3)) and three biochar amendment rates (5 t ha−1 (C1), 10 t ha−1 (C2), 15 t ha−1 (C3)). Soil physical indicators, salinity, and alfalfa yield are measured. The results showed that smaller drainage spacing and higher biochar amendment rates were beneficial for soil improvement, including bulk density, porosity, and field capacity. The experimental treatments affected the entire soil profile (0–80 cm), with subsurface drainage showing a greater impact on reducing salinity than biochar amendment. The S1 treatment had the most significant yield-increasing effect compared to other spacings. The increase in the biochar amendment rate promoted alfalfa yield, particularly for the first harvest. Overall, the results indicated that the drainage spacing of 6 m and the biochar amendment of 15 t ha−1 were most beneficial in improving soil properties in the plow layer and promoting alfalfa yield in saline–alkaline soils.
Full article
(This article belongs to the Special Issue Soil Water Use and Irrigation Management)
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Removal of Ibuprofen via the O3/H2O2 Oxidation System: Performance, Degradation Mechanism, and Toxicity Evaluation
by
Langning Li, Lele Fang, Jimin Shen, Binyuan Wang, Lei Yuan and Yuanqing Guo
Water 2025, 17(10), 1414; https://doi.org/10.3390/w17101414 - 8 May 2025
Abstract
Ibuprofen (IBF), as a representative emerging contaminant, poses urgent environmental and ecological risks that demand efficient removal technologies. This study employed an O3/H2O2 catalytic oxidation process to degrade IBF in aqueous systems and systematically investigated the effects of
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Ibuprofen (IBF), as a representative emerging contaminant, poses urgent environmental and ecological risks that demand efficient removal technologies. This study employed an O3/H2O2 catalytic oxidation process to degrade IBF in aqueous systems and systematically investigated the effects of reactant ratios, pH, and reactive species on the degradation efficiency. The results demonstrated that O3-dominated oxidation significantly outperformed H2O2 alone in IBF removal, with an optimal dosage ratio of c(O3):c (H2O2) = 6:1 and a removal efficiency of 94.75% at pH > 7. Radical quenching experiments confirmed that •OH served as the dominant reactive species, the concentration and stability of which directly governed the degradation kinetics. Combined density functional theory (DFT) calculations and mass spectrometry analysis revealed that the benzene ring and carboxyl groups in IBF were vulnerable to radical attack, with degradation pathways involving hydroxylation, decarboxylation, and ring-opening reactions, yielding 13 intermediate products. The toxicity assessment indicated that over 70% of these intermediates exhibited low or negligible toxicity. Remarkably, IBF removal efficiencies exceeded 99.4% in real water matrices (raw, filtered, and finished water), validating the robust anti-interference capability of the O3/H2O2 system. This process, characterized by high efficiency and low ecological risk, provides a feasible solution for eliminating trace emerging contaminants in advanced drinking water treatment.
Full article
(This article belongs to the Special Issue Applications of Catalytic Ozonation in Wastewater Treatment)
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Open AccessArticle
Economic Valuation of Ancestral Artificial Aquifer Recharge Systems in High Mountain Environments of Sierra Nevada, Spain
by
Wilber Vargas, Julio Berbel, Sandra del Aguila and Esther Díaz-Cano
Water 2025, 17(10), 1413; https://doi.org/10.3390/w17101413 - 8 May 2025
Abstract
The study applies a cost–benefit analysis approach to assess the ecosystem services provided by ancestral systems of artificial recharge of high mountain aquifers, the “acequias de careo” (careo channels), in the Bérchules River basin, located in the Sierra Nevada, Spain. The methodology is
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The study applies a cost–benefit analysis approach to assess the ecosystem services provided by ancestral systems of artificial recharge of high mountain aquifers, the “acequias de careo” (careo channels), in the Bérchules River basin, located in the Sierra Nevada, Spain. The methodology is structured in three main phases: (i) the definition of scenarios and system boundaries; (ii) the selection of ecological, social, and economic indicators; and (iii) the monetary valuation of benefits in comparison with operation and maintenance costs. The findings indicate that the studied system generates social, environmental, and economic benefits exceeding €22.2 million per year, while its operation requires only €43,352 annually. This gives a benefit/cost (B/C) ratio of 512, demonstrating its extremely high social profitability. These results highlight the potential of such infrastructures as nature-based solutions that can enhance water availability both temporally and spatially, mitigate the impacts of extreme events (such as droughts and floods), and strengthen local resilience to climate change. Moreover, they contribute to cultural heritage preservation and promote community cohesion.
Full article
(This article belongs to the Special Issue Balancing Competing Demands for Sustainable Water Development)
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Fate and Removal of Oxytetracycline and Antibiotic Resistance Genes in Vertical-Flow Constructed Wetland with Different Substrates
by
Wei Yuan, Yan Liu, Yijun Shang, Meng Bai, Leicheng Li, Xunan Li, Peiyuan Deng, Luqman Riaz, Yiping Guo and Jianhong Lu
Water 2025, 17(10), 1412; https://doi.org/10.3390/w17101412 - 8 May 2025
Abstract
The presence of antibiotics and antibiotic resistance genes (ARGs) in natural habitats has recently sparked increased concern. Vertical-flow constructed wetlands (VFCWs) represent a novel approach to reducing these new contaminants. In the current work, four laboratory-scale VFCW models with various substrates were built
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The presence of antibiotics and antibiotic resistance genes (ARGs) in natural habitats has recently sparked increased concern. Vertical-flow constructed wetlands (VFCWs) represent a novel approach to reducing these new contaminants. In the current work, four laboratory-scale VFCW models with various substrates were built to decrease oxytetracycline (OTC) and ARGs. The findings showed that the combination of zeolite and activated carbon exhibited high OTC removal efficiency (up to 97%), with lesser accumulation than in other experimental groups. Furthermore, the combination of zeolite and activated carbon had the lowest absolute and relative abundance of ARGs. This was ascribed to the synergistic benefits of zeolite and activated carbon in CW-D, which exceeded other VFCWs in terms of ARGs removal efficiency. The treatment groups had a considerable but not absolute inhibitory impact on ARGs proliferation; this was attributable to the fact that many dominant bacteria in the community under antibiotic stress were antibiotic-resistant, allowing ARGs to propagate more easily. Network analysis and correlation analysis emphasized the importance of horizontal gene transfer (HGT) in ARGs dissemination, and antibiotic pressure is unlikely to have a substantial influence on ARGs propagation in the medium-term future. Furthermore, it was found that hydrophilic phages and Legionella species might serve as possible hosts for ARGs.
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(This article belongs to the Section Water Quality and Contamination)
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Hybrid Coagulation–Membrane Filtration Techniques for Sustainable Soap Wastewater Treatment
by
Leila Merabti, Ouassila Benhabiles, Zahia Tigrine, Mounir Mellal, Nadia Chekir, Sarah Mahidine, Djilali Tassalit, Merouane Bentchikou, Amira Douadi, Linda Jammeli, Imen Khouni and Seif El Islam Lebouachera
Water 2025, 17(10), 1411; https://doi.org/10.3390/w17101411 - 8 May 2025
Abstract
Wastewater from soap production often contains high levels of organic pollutants, exceeding regulatory discharge limits and posing significant environmental concerns. This study investigates a two-stage treatment approach integrating ferric chloride (FeCl3)-based coagulation–flocculation with membrane filtration to enhance wastewater purification efficiency. This
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Wastewater from soap production often contains high levels of organic pollutants, exceeding regulatory discharge limits and posing significant environmental concerns. This study investigates a two-stage treatment approach integrating ferric chloride (FeCl3)-based coagulation–flocculation with membrane filtration to enhance wastewater purification efficiency. This method is one of the appropriate treatment techniques to reduce water pollution. Thus, numerous Jar test trials have been carried out in order to determine the optimal conditions and parameters that make it possible to reduce suspended solids. Key water quality parameters, including chemical oxygen demand (COD), pH, and turbidity, were monitored to assess process performance. Optimization experiments identified optimal coagulation–flocculation conditions, achieving a substantial COD reduction from 9200 mg/L to 351 mg/L significantly improving water quality. However, the treated effluent still failed to meet reuse standards, necessitating further purification. A subsequent membrane filtration stage was implemented, achieving a significant decrease in turbidity to 0.85 Ntu and a turbidity removal efficiency of 99.97%, indicating high treatment efficiency. The final COD of the collected water was 58 mg/L, well below regulatory limits. This hybrid treatment approach offers a highly effective and sustainable solution for soap wastewater management, supporting environmental protection and resource recovery.
Full article
(This article belongs to the Special Issue Advanced Biotechnologies for Water and Wastewater Treatment, 2nd Edition)
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Hydrochemical Characteristics and Quality Assessment of Groundwater in the Yangtze River Basin: A Comparative Study of the Hexian Area, China
by
Yonghong Xiao, Lu Wei, Xianghong Liu and Dengkui Yao
Water 2025, 17(10), 1410; https://doi.org/10.3390/w17101410 - 8 May 2025
Abstract
The quality of shallow groundwater in agricultural areas is being increasingly threatened by nitrogen pollution. However, the complex interactions between natural and anthropogenic sources remain insufficiently studied. In this study, the water chemical characteristics and nitrogen pollution sources in key agricultural areas and
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The quality of shallow groundwater in agricultural areas is being increasingly threatened by nitrogen pollution. However, the complex interactions between natural and anthropogenic sources remain insufficiently studied. In this study, the water chemical characteristics and nitrogen pollution sources in key agricultural areas and counties of the Yangtze River Basin were systematically investigated. Forty-three groundwater samples were analyzed for major ions and nitrides (NH4+, NO2−, NO3−) using hydrogeochemical analysis, spatial interpolation, and positive matrix factorization (PMF) models. The shallow groundwater in the study area is weakly alkaline (pH 7.36) and is dominated by calcium ions (mean 112.67 mg/L) and bicarbonate (mean 361.95 mg/L), which reveals that the hydrogeochemical characteristics are dominated by carbonate. The total hardness has increased, and the nitrogen concentration exhibits significant spatial variability. Nitrates (NO3−) exceed safety thresholds across the entire region and are strongly correlated with Cl−. The PMF analysis identified the following four major pollution factors: Factor 1 represents a combination of anthropogenic pollution and natural processes; Factor 2 is attributed to agricultural fertilizer application and septic tank leakage; Factor 3 is sourced from the weathering of carbonates and the decomposition of organic matter in a reducing environment; and Factor 4 is due to the leakage of domestic sewage or livestock-derived wastewater. Spatial analysis revealed pollution hotspots in the vicinity of urban, agricultural, and livestock areas. This study emphasizes that human activities, such as over-fertilization and inadequate wastewater management, are the main contributors to groundwater nitrogen pollution in the study area. In addition, we compare the groundwater quality of the entire Yangtze River Basin and find that there are distinct regional variations.
Full article
(This article belongs to the Special Issue Geochemistry and Removal of Heavy Metals and Other Pollutants in Water)
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Open AccessArticle
Verification of the Manning’s Roughness Coefficient of Fish Pass Riverbeds Using Drone-Based Photogrammetry
by
Lea Čubanová, Ján Rumann, Adela Rutzká, Alexandra Vidová and Peter Dušička
Water 2025, 17(10), 1409; https://doi.org/10.3390/w17101409 - 8 May 2025
Abstract
The accurate estimation of Manning’s roughness coefficient (n) is critical for hydraulic modeling in open channels. In fish passes designed as close-to-nature structures, this coefficient has a strong influence on the overall design and operation. This study evaluates n for the
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The accurate estimation of Manning’s roughness coefficient (n) is critical for hydraulic modeling in open channels. In fish passes designed as close-to-nature structures, this coefficient has a strong influence on the overall design and operation. This study evaluates n for the Veľké Kozmálovce fish pass using high-resolution drone imagery and image analysis techniques to determine riverbed surface characteristics and extract a grain size distribution curve. Various empirical equations based on Strickler’s formula were applied to specific grain sizes, yielding average n values of 0.036 and 0.037. Cowan’s method, which considers surface material, irregularities, vegetation, obstructions, and meandering, provided an upper-bound estimate of 0.040. However, this method is known to overestimate roughness in some cases. The Step-by-Step method, applied with hydraulic field measurements, resulted in a narrower range of n from 0.027 to 0.037. Overall, estimated values across all methods ranged between 0.023 and 0.040, reflecting the structural complexity of the fish pass, which includes boulders embedded in concrete and coarse gravel infill. These findings highlight the limitations of using generalized tabulated values for artificial channels and demonstrate that drone-based photogrammetry combined with empirical and analytical approaches can effectively capture spatial variability in hydraulic roughness.
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(This article belongs to the Special Issue Fishway Design and Development: New Challenges, Tools and Applications)
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Open AccessReview
A Systematic Review on the Influence of Drainage Systems on the Environment
by
Diana Kalibatienė, Rasa Stankevičienė and Oksana Survilė
Water 2025, 17(10), 1408; https://doi.org/10.3390/w17101408 - 8 May 2025
Abstract
Environmental research has become increasingly important due to the human impact on ecosystems, with a particular need to study how different drainage systems affect water quality. Improperly functioning drainage can result in significant losses of biogenic substances, soil erosion, eutrophication, and declining biological
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Environmental research has become increasingly important due to the human impact on ecosystems, with a particular need to study how different drainage systems affect water quality. Improperly functioning drainage can result in significant losses of biogenic substances, soil erosion, eutrophication, and declining biological capacity. This study addresses the existing knowledge gap by consolidating and critically analyzing the recent scientific literature on controlled and free draining types over forty years (1986–2024) using the Web of Science and Scopus databases. The objective of this systematic review is to collect and summarize information on various drainage systems, their advantages and disadvantages, and their effect on environmental water quality. A review of 144 selected papers from the past four decades indicates that the installation, use, and upgrading of drainage systems remains a subject of extensive debate within the scientific community, particularly regarding their impact on the leaching of biogenic substances into open water bodies. The results obtained from this study indicate that nitrogen (N) (found in 54 papers) and phosphorus (P) (found in 48 papers) are the primary biogenic elements affecting aquatic ecosystems and eutrophication processes. Also, compared to mathematical tools (found in 42 articles), there is a lack of application of AI tools for modeling and predicting the impact of drainage systems on water quality and climate change. Consequently, ongoing research in this area is crucial, offering researchers, practitioners, and wild society with significant insights into the overall effect of drainage on the environment, opportunities for improvement and unexplored research directions for drainage systems.
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(This article belongs to the Section Water Quality and Contamination)
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Open AccessArticle
Microstructural Evolution and Mechanical Properties of Fly-Ash-Based Grouting Materials in Different Aqueous Environments
by
Jianwei Chen, Yan Qin, Fengdan Hu, Nengxiong Xu, Yuxi Guo, Jiayu Qin and Guangming Ren
Water 2025, 17(10), 1407; https://doi.org/10.3390/w17101407 - 8 May 2025
Abstract
Grouting is widely used in the treatment works of goaf, which can enhance the foundation bearing capacity, reduce deformation, and ensure the stability of the construction of goaf. As the goaf is located below the water table line, the mechanical properties and microscopic
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Grouting is widely used in the treatment works of goaf, which can enhance the foundation bearing capacity, reduce deformation, and ensure the stability of the construction of goaf. As the goaf is located below the water table line, the mechanical properties and microscopic changes of the stone body in the water-rich environment have not been revealed, which leads to the effect of grouting treatment in water-rich goaf being difficult to achieve in terms of the expected goal. This paper used uniaxial compression, electron microscopy (SEM), and X-ray diffraction (XRD) to study the mechanical properties and microscopic changes of the nodular body under natural, pure water, and tap water curing and revealed the deterioration mechanism of the nodular body’s mechanical properties under water curing. The research results show that under identical material proportions and curing durations, compared to naturally cured specimens, the specimens cured in purified water and tap water exhibited a significant increase in the content of unreacted fly ash, a reduction in the amount of hydration products such as C-S-H gel and ettringite, and a looser microstructure, resulting in average decreases in uniaxial compressive strength of 35.7% and 49.9%, respectively. In addition, the presence of chloride ions and Friedel’s induced decalcification of the C-S-H gel under tap water curing conditions led to a significant deterioration in the physical strength of the grouted stones.
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(This article belongs to the Special Issue Rock Mechanics and Rock Engineering Problems Caused by Water Action)
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Open AccessArticle
A Multi-Source Object-Oriented Framework for Extracting Aquaculture Ponds: A Case Study from the Chaohu Lake Basin, China
by
Lingyan Qi, Zhengxin Wang, Liuyi Dai, Fengwen Wu, Han Yin, Kejia Zhang, Mingzhu Guo, Liangtao Ye and Shanshan Zhang
Water 2025, 17(9), 1406; https://doi.org/10.3390/w17091406 - 7 May 2025
Abstract
Quantifying the extent and distribution of aquaculture ponds has become the key to management in the aquaculture industry, thereby contributing to the sustainable development of the region. However, accurate extraction of individual aquaculture pond boundaries from mesoscale remote sensing images remains a significant
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Quantifying the extent and distribution of aquaculture ponds has become the key to management in the aquaculture industry, thereby contributing to the sustainable development of the region. However, accurate extraction of individual aquaculture pond boundaries from mesoscale remote sensing images remains a significant challenge. In this work, we developed the Multi-source Object-oriented Framework for extracting Aquaculture ponds (MOFA) to address mapping challenges in the Chaohu Lake basin, China. The MOFA combined Sentinel-1 synthetic aperture radar (SAR) with Sentinel-2 data, applying an object-oriented approach with adaptive threshold segmentation for robust and automated aquaculture pond delineation. Our performance evaluation results showed that the overall accuracy is as high as 90.75%. The MOFA is thus capable of distinguishing seasonal water bodies, lakes, reservoirs, and rivers from individual (non-centralized, contiguous) aquaculture ponds. Our results showed that the central and south sections of the Chaohu Lake basin are characterized by denser aquaculture pond distributions, relative to those in the western basin. The total area of aquaculture ponds across the entire basin decreased from 19,297.86 hm2 in 2016 to 18,262.77 hm2 in 2023, which is likely attributed to local policy adjustments, resource optimization, shifting market demands, or natural environmental changes. The abandonment and unregulated expansion of aquaculture ponds threaten sustainable development. Local governments must implement adaptive governance strategies to balance ecological preservation with economic growth. Overall, the MOFA can quickly and accurately extract and map aquaculture ponds, and further support the scientific planning of sustainable aquaculture development.
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(This article belongs to the Special Issue Wetland Water Quality Monitoring and Assessment)
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Open AccessArticle
Runoff Prediction Method Based on Pangu-Weather
by
Wentao Yang, Hui Qin, Yongsheng Jie, Yuhua Qu, Taiheng Zhang, Chenghong Li and Li Tan
Water 2025, 17(9), 1405; https://doi.org/10.3390/w17091405 - 7 May 2025
Abstract
Runoff prediction is a complex hydrological, nonlinear time-series problem. Many machine learning methods have been put forth in recent years to predict runoff. A sliding window method is typically used to preprocess the data in order to rebuild the time series of runoff
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Runoff prediction is a complex hydrological, nonlinear time-series problem. Many machine learning methods have been put forth in recent years to predict runoff. A sliding window method is typically used to preprocess the data in order to rebuild the time series of runoff data into a standard machine learning dataset. The size of the window is a variable parameter that is commonly referred to as the time step. With developments in computer and AI technology, data-driven models have demonstrated tremendous potential for runoff prediction. And AI technology has opened up a new avenue for weather prediction, with Pangu-Weather demonstrating considerable improvements in both accuracy and processing efficiency. This study creates two novel prediction models, LSTM-Pangu and GRU-Pangu, by combining Pangu with Long Short-Term Memory (LSTM) and the Gate Recurrent Unit (GRU). We concentrated on the Beipanjiang River Basin in China, using Guizhou Qianyuan Power Company Limited’s daily runoff data and meteorological satellite data from the Climate Data Store platform to forecast daily runoff. These models were used to anticipate runoff on various future days (known as the lead time). The results show that regardless of time step, both LSTM-Pangu and GRU-Pangu outperform the LSTM and GRU models. Furthermore, this advantage is more evident as the advance time increases. When the time step is 7 and the lead time is 5, the Nash–Sutcliffe Efficiency (NSE) of the LSTM-Pangu model improves by 8.1% compared to the LSTM model, while the NSE of the GRU-Pangu model improves by 11.7% compared to the GRU model. Furthermore, LSTM-Pangu and GRU-Pangu outperform LSTM and GRU models in terms of the predictive accuracy under high-flow conditions, highlighting their significant advantages in flood forecasting. This integration strategy displays great transferability and may be expanded to other typical data-driven models.
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(This article belongs to the Section Hydrology)
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Open AccessArticle
Urban Flood Prediction Model Based on Transformer-LSTM-Sparrow Search Algorithm
by
Zixuan Fan, Jinping Zhang, Yanpo Chen and Hongshi Xu
Water 2025, 17(9), 1404; https://doi.org/10.3390/w17091404 - 7 May 2025
Abstract
Global climate change and accelerated urbanization have intensified extreme rainfall events, exacerbating urban flood risks. Although data-driven models have shown potential in urban flood prediction, the ability of single models to capture complex nonlinear relationships and their sensitivity to hyperparameters still limit prediction
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Global climate change and accelerated urbanization have intensified extreme rainfall events, exacerbating urban flood risks. Although data-driven models have shown potential in urban flood prediction, the ability of single models to capture complex nonlinear relationships and their sensitivity to hyperparameters still limit prediction accuracy. To address these challenges, this study proposes an urban flood prediction model by integrating Transformer, Long Short-Term Memory (LSTM), and Sparrow Search Algorithm (SSA), combining Transformer’s global feature extraction with LSTM’s temporal modeling. The SSA was adopted to optimize hyperparameters for the Transformer-LSTM model. Dropout and early stopping techniques were adopted to mitigate overfitting. Applied to Zhengzhou city of Henan province, China, the model achieves a Nash-Sutcliffe Efficiency (NSE) of 0.971, indicating that the proposed model has high prediction performance for urban flooding. The experimental results demonstrate that the Transformer-LSTM-SSA model outperforms the standalone Transformer, LSTM, and Transformer-LSTM models by 12.9%, 10.1%, and 2.9% in NSE accuracy, respectively, while reducing MAE by 62.12%, 56.9%, and 34.21%, respectively, and MAPE by 21.69%, 22.2%, and 10.89%, respectively. Furthermore, the proposed model exhibits enhanced stability and superior generalization capability. The Transformer-LSTM-SSA model exhibits superior performance among the comparative methods, thereby demonstrating the model’s viability for providing a reliable solution for real-time flood prediction and early warning.
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(This article belongs to the Special Issue Urban Flood Frequency Analysis and Risk Assessment)
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