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The Reliability of SBR System During COVID-19 and Its Impact on Water Quality of a Small Flysch River in Protected Areas -
Scales and Sustainability: The Politics of Riverine Landscape Governance in Chiang Mai, Thailand -
Low-Cost, Sustainable Materials and 3D-Printed Systems for Wastewater Treatment and Reuse in Rural Communities: A Critical Review
Journal Description
Water
Water
is a peer-reviewed, open access journal on water science and technology, including the ecology and management of water resources, published semimonthly online by MDPI. Water collaborates with the Stockholm International Water Institute (SIWI). In addition, the American Institute of Hydrology (AIH), 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 (Aquatic Science)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 17.7 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the first half of 2026).
- 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: Hydropower and Freshwater.
- Journal Clusters of Water Resources: Water, Journal of Marine Science and Engineering, Hydrology, Resources, Oceans, Limnological Review, Coasts and Hydropower.
Impact Factor:
3.5 (2025);
5-Year Impact Factor:
3.6 (2025)
Latest Articles
Hydrodynamic Mechanisms of Regulated Lake–Aquifer Exchange and Near-Shore Groundwater Salinization in an Arid Wetland
Water 2026, 18(16), 1934; https://doi.org/10.3390/w18161934 - 7 Aug 2026
Abstract
At Yuehai Lake, China, managed Yellow River diversion maintains open water while imposing a persistent hydraulic boundary on the shallow aquifer. We combined water balance, zonal Darcy estimation, a calibrated regulated-stage groundwater model, particle tracking, major ions, and stable isotopes. Yellow River diversion
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At Yuehai Lake, China, managed Yellow River diversion maintains open water while imposing a persistent hydraulic boundary on the shallow aquifer. We combined water balance, zonal Darcy estimation, a calibrated regulated-stage groundwater model, particle tracking, major ions, and stable isotopes. Yellow River diversion supplied 93.7% of quantified external inflows. Zonal Darcy and model leakage were 2.39 and 2.47 × 106 m3 a−1. Across the monitored stage range (1105.96–1106.42 m), modeled leakage was 2.41–2.53 × 106 m3 a−1; alternative upper-aquifer structures produced 1.91–3.02 × 106 m3 a−1 without reversing exchange or eliminating the mound. Particles from 441 lakebed cells moved a median 24.5 m over 1065 d, indicating slow near-shore advection. Selected-screen isotopes were consistent with evaporatively enriched lake-water influence, whereas major ions showed a distinct west–east shift from Ca–Mg–HCO3 toward Na–SO4 and Na–Cl facies. Yuehai Lake therefore functions as a regulated losing lake. Its salinity pattern likely reflects lake leakage, agricultural return flow, soil-salt mobilization, background saline groundwater, and restricted drainage. Management should integrate lake-stage, groundwater-flow, and salinity monitoring.
Full article
(This article belongs to the Section Hydrogeology)
Open AccessArticle
Water Transport Characteristics and Their Impaction on Stability of Unsaturated Xiashu Loess Slopes During the Entire Process of Rainfall Infiltration
by
Zhiyao Kuai, Xuan Zhang, Lian Liu, Juncheng Dai, Xue Gao, Yi Wang, Pan Xiao and Faming Zhang
Water 2026, 18(16), 1933; https://doi.org/10.3390/w18161933 - 7 Aug 2026
Abstract
The Xiashu loess in the middle and lower reaches of the Yangtze River with typical aeolian characteristics is widely distributed in the hilly areas and is the main kind of landslides in this area. The paper reveals the infiltration process of the Xiashu
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The Xiashu loess in the middle and lower reaches of the Yangtze River with typical aeolian characteristics is widely distributed in the hilly areas and is the main kind of landslides in this area. The paper reveals the infiltration process of the Xiashu loess slope under different rainfall intensity conditions on the basis of on-site artificial rainfall simulation tests and laboratory experiments. The distribution of pore water pressure inside the Xiashu loess slope under different rainfall intensity conditions were compared and analyzed. The relationship between rainfall intensity and water content at different depths was clarified, and the relation function among rainfall intensity conditions, slopes, and the ultimate depth and critical rainfall intensity of the Xiashu soil slope landslide is proposed. The research results indicate that: (1) the infiltration rate and depth of the soil at the foot of the slope are greater than those at the top and middle of the slope; (2) an increase in the rainfall duration is found to cause an increase in slope infiltration depth; (3) an increase in the rainfall duration can lead to a more significant influence of the infiltration depth under the slope angle; (4) the infiltration depth of rainfall with low intensities and long durations is larger than that of high intensities and short durations. Finally, the ultimate rainfall infiltration depth under different slope angles and rainfall conditions was determined. The research results can be used to forecast the Xiashu loses soil landslide scale, providing theoretical basis for early warning of instability of Xiashu loess slope under different unfavorable conditions.
Full article
(This article belongs to the Special Issue Landslide and Slope Stability Risk Assessment: Study of Rainfall-Induced Shallow Landslide)
Open AccessArticle
Time Series Prediction of Key Indicators of Aquatic Ecological Health in the Xiaoqing River Based on Differential Attention Mechanism
by
Yonggang Li, Yan Wang, Zhiyuan Wang, Ke Li, Zhongzhu Zhu, Shuaishuai Wang, Ning Li and Jinfeng Ma
Water 2026, 18(16), 1932; https://doi.org/10.3390/w18161932 - 7 Aug 2026
Abstract
Accurate assessment of aquatic ecological health relies on the effective characterization of the temporal dynamics of key water quality and algal indicators. To address challenges such as strong non-stationarity, significant noise interference, and complex multivariate coupling in water environment monitoring time series, this
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Accurate assessment of aquatic ecological health relies on the effective characterization of the temporal dynamics of key water quality and algal indicators. To address challenges such as strong non-stationarity, significant noise interference, and complex multivariate coupling in water environment monitoring time series, this paper introduces a differential attention mechanism (DIFF Transformer) and constructs a time series prediction model for key indicators of aquatic ecological health. Taking the Huangtaiqiao monitoring section of the Xiaoqing River in Jinan, China, as the study area, multivariate time series prediction research was conducted for key proxy indicators of aquatic ecological health, including blue-green algae, chlorophyll, dissolved oxygen, turbidity, total phosphorus, ammonia nitrogen, permanganate index, and TOC, based on hourly measured data from 2017 to 2024. The results show that the differential attention mechanism improves balanced forecasting across multiple water quality and algal indicators by reducing isolated and unstable high-frequency residual fluctuations and enhancing the reconstruction of dominant temporal patterns. Compared with LSTM, GRU, and the standard Transformer, DIFF Transformer achieved the highest macro-averaged Nash-Sutcliffe efficiency coefficient among the learning-based models, with a macro-averaged NSE of 0.93. Per-indicator evaluation further showed that DIFF Transformer achieved NSE values above 0.95 for 11 of the 12 water quality indicators. In addition, DIFF Transformer obtained lower MSE, MAE, and RMSE than LSTM, GRU, and the standard Transformer. These results indicate that DIFF Transformer can provide continuous, stable, and high-temporal-resolution predictions of key aquatic ecological proxy indicators, supporting routine water quality trend tracking and dynamic aquatic ecological assessment.
Full article
(This article belongs to the Special Issue Water Pollution Assessment, Control, and Resource Recovery)
Open AccessEditorial
Remote Sensing in Coastal Water Environment Monitoring: Advancements, Challenges, and Future Perspectives
by
Peng Li, Fengqin Yan and Xiuling Zuo
Water 2026, 18(16), 1931; https://doi.org/10.3390/w18161931 - 7 Aug 2026
Abstract
Coastal zones and major river deltas represent Earth’s most socio-economically vital and ecologically dynamic domains, responsible for indispensable ecosystem functions, such as blue carbon sequestration and shoreline stabilization [...]
Full article
(This article belongs to the Special Issue Remote Sensing in Coastal Water Environment Monitoring)
Open AccessArticle
Sensitivity of Reservoir Performance to Hydroclimatic Forcing Pathways: A Coupled SWAT+–MSPA-2024 Framework
by
Issa Saket Oskoui, Maria Manuela Portela and Carina Almeida
Water 2026, 18(16), 1930; https://doi.org/10.3390/w18161930 - 7 Aug 2026
Abstract
Accurate reservoir performance assessment increasingly relies on hydrological model-derived inflow series; however, the effects of hydroclimatic forcing pathways on reservoir design outcomes remain insufficiently understood. This study evaluates the sensitivity of reservoir performance to alternative forcing pathways by comparing observed inflows with SWAT+-simulated
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Accurate reservoir performance assessment increasingly relies on hydrological model-derived inflow series; however, the effects of hydroclimatic forcing pathways on reservoir design outcomes remain insufficiently understood. This study evaluates the sensitivity of reservoir performance to alternative forcing pathways by comparing observed inflows with SWAT+-simulated streamflow driven by ERA5-Land reanalysis data in the Cidadelhe catchment, Portugal. An integrated hydrology–reservoir modeling framework couples SWAT+ simulations with three analytical approaches: Behavior Analysis, the Modified Sequent Peak Algorithm (MSPA), and the Resilience-Regulated MSPA-2024. Results show that, despite strong hydrological model performance (NSE up to 0.83), SWAT+-simulated inflows exhibit systematic attenuation of variability, approximately 20–25%, leading to substantially lower storage capacity (up to 60–65%) and evaporation estimates relative to those derived from observed data. While volumetric reliability remains largely insensitive to forcing pathways, resilience, sustainability, and drought risk indices display pronounced method-dependent behavior. MSPA-2024 demonstrates strong robustness by maintaining near-invariant performance metrics across forcing conditions through embedded resilience constraints. These findings show that inflow statistical structure, rather than mean flow alone, controls reservoir design outcomes and that forcing-pathway consistency is critical for reliable performance assessment. The proposed SWAT+–MSPA-2024 framework supports more reliable model-based reservoir planning, particularly in data-scarce basins and climate-scenario applications.
Full article
(This article belongs to the Special Issue Managing Water Under a New Hydrological Normal: Innovations for Resilience in the Face of Climate Change)
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Open AccessArticle
Dependence of Simulated High Flows and Flood Events on Meteorological Forcing Products in the Songhua River Basin: A CLM5–CaMa-Flood Assessment
by
Mingshuo Li, Heng Li, Wenwu Ni, Jing Wang and Yuhang Jiang
Water 2026, 18(16), 1929; https://doi.org/10.3390/w18161929 - 7 Aug 2026
Abstract
Reliable flood simulation in large cold-region basins requires understanding how meteorological forcing differences propagate through runoff generation and river routing. We compared CMFD, GSWP3v1, and CRUNCEPv7 using a controlled, uncalibrated offline CLM5–CaMa-Flood framework for the Songhua River Basin during 1996–2014, with all non-forcing
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Reliable flood simulation in large cold-region basins requires understanding how meteorological forcing differences propagate through runoff generation and river routing. We compared CMFD, GSWP3v1, and CRUNCEPv7 using a controlled, uncalibrated offline CLM5–CaMa-Flood framework for the Songhua River Basin during 1996–2014, with all non-forcing settings fixed. Evaluation included daily and monthly discharge, seasonal hydrographs, annual maximum daily discharge (AMAX), observed Q95/Q99 thresholds, selected 1998 and 2013 warm-season high-flow cases, runoff-process diagnostics, event-window sensitivity tests, 5000 paired year-wise bootstrap resamples, and auxiliary water-level anomalies. CMFD generally produced the highest r, KGE, and daily NSE, but also the largest positive long-term Bias. CRUNCEPv7 systematically underestimated discharge, whereas GSWP3v1 more often yielded the smallest absolute Bias. For both selected events, CMFD reduced peak and volume underestimation, although peaks remained smoothed and delayed. Event-window precipitation differences did not translate proportionally into CLM5 runoff, and the larger CMFD response involved increases in both surface runoff and subsurface drainage. The event-magnitude ordering remained stable across ±30-, ±45-, and ±60-day windows. Bootstrap results showed a robust CMFD advantage over GSWP3v1 for temporal agreement and efficiency, while several CMFD–CRUNCEPv7 comparisons remained sample-dependent. Forcing-product performance was therefore scale-, metric-, and target-dependent and conditional on the fixed model configuration.
Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle
Nitrogen-Doped Carbon-Encapsulated Co–Fe Catalyst for Efficient Peroxymonosulfate Activation Toward Rhodamine B Degradation
by
Yixin Pan, Yajun Chen, Wenshuo Zhang and Xiaofan Lv
Water 2026, 18(16), 1928; https://doi.org/10.3390/w18161928 - 7 Aug 2026
Abstract
A nitrogen-doped carbon-confined cobalt–iron bimetallic catalyst (CFNC) was fabricated through high-temperature pyrolysis of a ZIF-67-modified CoFe2O4 precursor and employed as a heterogeneous activator for peroxymonosulfate (PMS)-mediated Rhodamine B (RhB) degradation. The physicochemical properties of the as-prepared catalyst were investigated by
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A nitrogen-doped carbon-confined cobalt–iron bimetallic catalyst (CFNC) was fabricated through high-temperature pyrolysis of a ZIF-67-modified CoFe2O4 precursor and employed as a heterogeneous activator for peroxymonosulfate (PMS)-mediated Rhodamine B (RhB) degradation. The physicochemical properties of the as-prepared catalyst were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. These analyses demonstrated that Co–Fe bimetallic species were successfully embedded within the nitrogen-doped carbon framework, forming a confined carbon-supported catalytic structure. Under optimized conditions (CFNC dosage of 20 mg L−1, PMS concentration of 150 mg L−1, and initial pH of 7), the CFNC/PMS system achieved 99.45% RhB removal within 10 min. Moreover, the catalyst retained 78.91% degradation efficiency after five successive cycles, indicating its satisfactory reusability and structural stability. Mechanistic investigations based on radical scavenging experiments and electron paramagnetic resonance (EPR) analysis revealed that PMS activation over CFNC involved the coexistence of radical and non-radical oxidation pathways, in which singlet oxygen (1O2) played a predominant role. The defect-rich nitrogen-doped carbon matrix facilitated PMS adsorption and activation, promoting the selective formation of 1O2, while the confined Co–Fe bimetallic sites contributed to efficient electron transfer during the catalytic process. The synergistic coupling between the Co–Fe active centers and conductive carbon framework accounted for the enhanced catalytic performance, suppressed metal leaching, and long-term stability of CFNC. This work presents a promising approach for constructing robust bimetallic carbon-based catalysts and advances the application of PMS-driven advanced oxidation processes for wastewater remediation.
Full article
(This article belongs to the Special Issue Monitor and Degradation of Emerging Pollutants in Water)
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Open AccessArticle
OSL Dating and Documentary Constraints on the Disappearance of Paleolakes Around Tongwan City and Its Implications for the Abandonment of Tongwan City
by
Yanfang Yang, Rihui Huang, Baosheng Li, Ranming Guo, Yuejun Si and Long Huang
Water 2026, 18(16), 1927; https://doi.org/10.3390/w18161927 - 7 Aug 2026
Abstract
The formation and disappearance of paleolakes are sensitive indicators of environmental evolution in arid and semi-arid regions. Their disappearance records comprehensive information on regional hydrological conditions, climatic changes, and tectonic activities, thereby offering unique research value for elucidating the environmental driving mechanisms behind
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The formation and disappearance of paleolakes are sensitive indicators of environmental evolution in arid and semi-arid regions. Their disappearance records comprehensive information on regional hydrological conditions, climatic changes, and tectonic activities, thereby offering unique research value for elucidating the environmental driving mechanisms behind water resource changes in historical human settlements and the concomitant rise and fall of civilizations. This study analyzed the contact interface between extensively distributed lacustrine deposits and the overlying aeolian dune sands around Tongwan City using optically stimulated luminescence (OSL), and combined with relevant documentary evidence to elucidate the relationship between paleolake disappearance and the abandonment of the ancient city. The OSL dating results demonstrated that the disappearance of paleolakes and the initiation of desertification around Tongwan City were mainly concentrated between about 1200 and 900 years before present, closely corresponding to the abandonment of Tongwan City in AD 994. Field investigations additionally revealed that well-developed fluvial erosion surfaces are pervasively present at the top of lacustrine deposits around Tongwan City, while multiple fluvial terraces are exposed along the Wuding River. These features collectively indicate that regional crustal uplift event led to fluvial incision. The results indicated that the abandonment of Tongwan City was not attributable solely to climatic aridification, but instead resulted from the combined influences of favorable hydrothermal conditions during the High-Temperature Period of the Northern Song (HTNS, AD 994–1094) and regional tectonic uplift. Tectonic uplift facilitated deep incision of the Wuding River valley, while increased precipitation during the warm period enhanced surface water infiltration and drainage, resulting in a significant decline in groundwater levels, the disappearance of paleolakes, and ultimately the depletion of water resources upon which the ancient city relied. These findings provide new evidence from an environmental geological perspective and present a key scientific explanation for the paradox that Tongwan City was abandoned during a relatively warm climatic interval. Furthermore, the coupled mechanism of tectonic uplift, fluvial incision, sharp groundwater decline, and societal collapse revealed in this study not only provides a valuable reference for investigating the abandonment of ancient cities in arid and semi-arid regions during historical periods, but also offers important implications for assessing water resource vulnerability of ancient settlements on analogous geomorphic units under global climate change, and may serve as a geological–historical warning and reference for water security management in human habitations under current and future warm-climate conditions.
Full article
(This article belongs to the Special Issue Climate Change and Hydrological Processes, 3rd Edition)
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Open AccessArticle
A Comparative Study of Deep Learning-Based Models for Mine Water Inflow Prediction
by
Lujun Chai, Zhuolin Li, Fanjun Wang, Xin Huang and Kun Wu
Water 2026, 18(16), 1926; https://doi.org/10.3390/w18161926 - 7 Aug 2026
Abstract
To address the need for high-precision prediction of mine water inflow under complex geological conditions, this study proposes a hybrid deep learning framework for accurate water inrush forecasting. Using daily water inrush records and nine meteorological and hydrological variables collected from the Maoping
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To address the need for high-precision prediction of mine water inflow under complex geological conditions, this study proposes a hybrid deep learning framework for accurate water inrush forecasting. Using daily water inrush records and nine meteorological and hydrological variables collected from the Maoping mining area in northeastern Yunnan Province, China, in 2023, five deep learning models, namely, CNN, LSTM, Transformer, CNN-LSTM, and LSTM-Transformer, were systematically developed and comparatively evaluated. The results demonstrate that the LSTM-Transformer hybrid model achieved the best predictive performance, with an MAE of 0.196, an RMSE of 0.243, and an R2 of 0.882 outperforming both the individual deep learning models and other hybrid architectures. By combining the temporal memory capability of LSTM with the global attention mechanism of Transformer, the proposed model effectively captures the nonlinear, non-stationary, and multi-scale temporal dependencies embedded in mine water inflow series, thereby substantially enhancing prediction accuracy. These findings indicate that hybrid deep learning architectures integrating local temporal memory with global attention mechanisms provide a robust and effective approach for complex engineering time-series forecasting, offering valuable support for high-precision early warning and intelligent prevention of mine water inflow hazards.
Full article
(This article belongs to the Section Hydrogeology)
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Open AccessArticle
Draft Tube Wake Vortex Evolution and Suppression in a Pump as Turbine with Splitter Blades Based on a Modified Burgers Vortex Model
by
Chenguang Wang, Wang Zheng, Yingxiao Shi, Hua Liu, Dazhuan Wu and Qiaorui Si
Water 2026, 18(16), 1925; https://doi.org/10.3390/w18161925 - 7 Aug 2026
Abstract
Owing to its efficient energy recovery capability, the pump as turbine (PAT) has attracted considerable attention and has been widely applied in micro hydropower systems. However, under off-design conditions, large-scale helical vortex ropes are readily induced in the draft tube, causing severe hydraulic
[...] Read more.
Owing to its efficient energy recovery capability, the pump as turbine (PAT) has attracted considerable attention and has been widely applied in micro hydropower systems. However, under off-design conditions, large-scale helical vortex ropes are readily induced in the draft tube, causing severe hydraulic losses and flow instability. Because existing theoretical models do not account for the slip effect at the impeller outlet, this study combines vortex dynamics theory with numerical simulation and introduces a correction coefficient to develop a Burgers vortex-based analytical wake vortex model for a PAT with splitter blades. The model is verified by its ability to predict the peak tangential velocity and radial decay trend of the vortex core. In addition, the influence of draft tube configuration on vortex rope evolution is revealed using the Liutex vortex identification method and enstrophy analysis. The results show that the geometric curvature of the elbow draft tube induces vortex rope breakup and high energy dissipation. Finally, entropy production theory is used to quantitatively evaluate the vortex suppression benefit and hydraulic loss caused by deflector plates. The results indicate that the transverse deflector plate (TDP) provides a significantly better suppression effect than the longitudinal deflector plate (LDP) by disrupting the circumferential continuity of the vortex rope. Although increasing the insertion depth of the deflector plate improves vortex suppression, it induces non-negligible local high-entropy production on the upstream-facing surface (US). This study clarifies the physical mechanism of wake vortices in a PAT with splitter blades and provides theoretical guidance for efficient PAT operation and wake vortex control.
Full article
(This article belongs to the Special Issue Advances in Hydrodynamics for Pumping Systems: Modeling, Optimization, and Applications, 2nd Edition)
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Open AccessArticle
On Reduced Observer-Bank Synthesis and Edge Implementation for Residual Chlorine Concentration Soft Sensors in Water Distribution Networks
by
Nikolaos D. Kouvakas, Fotis N. Koumboulis, Antonios N. Menexis, Dimitrios G. Fragkoulis and Maria P. Tzamtzi
Water 2026, 18(15), 1924; https://doi.org/10.3390/w18151924 - 6 Aug 2026
Abstract
In the present paper, a reduced observer-bank synthesis and edge-oriented implementation framework for a model-based residual chlorine concentration soft sensor in water distribution networks is presented. For a benchmark network described through nonlinear hydraulic and chlorine transport–reaction dynamics, local discrete-time linear approximants are
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In the present paper, a reduced observer-bank synthesis and edge-oriented implementation framework for a model-based residual chlorine concentration soft sensor in water distribution networks is presented. For a benchmark network described through nonlinear hydraulic and chlorine transport–reaction dynamics, local discrete-time linear approximants are derived around admissible operating points. Based on these approximants, a finite bank of full-order Luenberger-type observers is designed for the estimation of nonmeasurable chlorine concentration variables. The observer parameters are selected through a metaheuristic multicriterion tuning procedure that combines discrete-time pole-placement requirements with estimation-performance objectives. A central contribution of the paper is an observer-bank construction algorithm that eliminates redundant target operating areas. The algorithm adaptively covers the normalized input domain by generating each observer operating area after nonlinear steady-state computation, local linearization, observer tuning, and validation for each operating point. The resulting observer bank is combined with a switching supervisor based on target-area overlap and measurable-output convergence. The resulting scheme is implemented in a Node-RED edge runtime, where multiple observers execute in parallel and the supervisor/switching mechanism selects the active observer that provides the appropriate estimate. Deterministic telemetry generated by a MATLAB R2025b simulation of the water distribution network is fed to the Node-RED instance, enabling repeatable evaluation of acquisition, estimation, switching, single-stream telemetry arbitration, and runtime adaptation. Computational and edge runtime experiments demonstrate the feasibility of deploying the proposed switching-observer soft sensor for real-time chlorine monitoring in water distribution networks.
Full article
(This article belongs to the Special Issue Sustainable Management of Water Distribution Networks)
Open AccessReview
Surfactants for Electrokinetic Remediation of Hydrophobic Organic Contaminants in Soil–Water Systems
by
Yang Wu, Xingbo Duan, Xiaoshan Zhao, Mingyue Li, Yumiao Ran, Yunlong Li and Xuekai Dou
Water 2026, 18(15), 1923; https://doi.org/10.3390/w18151923 - 6 Aug 2026
Abstract
Hydrophobic organic compounds (HOCs) in water–soil systems pose persistent risks to pore water quality and groundwater safety because of their low aqueous solubility and strong soil sorption affinity. Electrokinetic remediation has emerged as a promising technology for controlling HOCs in contaminated water–soil systems,
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Hydrophobic organic compounds (HOCs) in water–soil systems pose persistent risks to pore water quality and groundwater safety because of their low aqueous solubility and strong soil sorption affinity. Electrokinetic remediation has emerged as a promising technology for controlling HOCs in contaminated water–soil systems, as it can regulate pore water movement, ionic migration, and contaminant transport under an applied electric field. However, the limited transfer of HOCs from soil into the aqueous phase restricts their electrokinetic removal efficiency, necessitating the use of surfactants to overcome these technical bottlenecks. This review elucidates the mechanistic basis of surfactant-enhanced electrokinetic remediation, with particular emphasis on micellar solubilization in pore water, contaminant desorption from soil matrices, and electrically driven transport across water–soil interfaces. Building on this mechanistic framework, the applications and performance of nonionic, anionic, cationic, biosurfactant, and mixed surfactants are summarized. Furthermore, the key factors governing surfactant efficacy are analyzed, including soil properties, contaminant characteristics, remediation objectives, operational parameters, environmental safety, and economic feasibility. By integrating mechanistic insights with environmental considerations, this review establishes a science-based framework for surfactant selection in electrokinetic remediation. This work provides a reference for enhancing contaminant transfer from soil matrices to the aqueous phase, reducing secondary risks to pore water and groundwater, and advancing the theoretical development and implementation of surfactant-enhanced electrokinetic remediation in environmental management.
Full article
(This article belongs to the Special Issue Water Environment Pollution and Control, 5th Edition)
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Open AccessArticle
Long-Term Evaluation of Satellite Precipitation Products for Extreme Rainfall and Water-Related Hazard Assessment Along a Mountainous Corridor in Northern Vietnam
by
Doan Thi Noi, Nguyen Hoang Son, Dang Thu Thuy, Nguyen Thanh Nga and Tran Thu Phuong
Water 2026, 18(15), 1922; https://doi.org/10.3390/w18151922 - 6 Aug 2026
Abstract
Accurate rainfall information is essential for water-related hazard assessment in mountainous regions, where complex terrain and sparse gauge networks limit monitoring reliability. This study evaluated long-term rainfall characteristics and the performance of three satellite precipitation products—CHIRPS, GPM IMERG, and GSMaP—along the National Highway
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Accurate rainfall information is essential for water-related hazard assessment in mountainous regions, where complex terrain and sparse gauge networks limit monitoring reliability. This study evaluated long-term rainfall characteristics and the performance of three satellite precipitation products—CHIRPS, GPM IMERG, and GSMaP—along the National Highway 6 corridor in northern Vietnam. Daily gauge observations from 11 meteorological stations with station-dependent records between 1961 and 2024 were used to characterize rainfall variability and heavy-rainfall frequency. Matched gauge–satellite records from 2001 to 2024 were evaluated using continuous statistical indicators, contingency-table metrics, empirical cumulative distribution functions, and percentile-based analysis. Data from 2025 were additionally examined as an extreme-rainfall case study, supplemented by visual gauge–satellite comparisons; however, these data were not used as an independent satellite-validation period. The long-term gauge records showed marked spatial variability in rainfall magnitude and threshold-exceedance frequency. In 2025, all 11 stations recorded daily rainfall exceeding 50 mm, while eight stations recorded events exceeding 100 mm. Satellite-product performance varied substantially among stations, rainfall thresholds, and evaluation metrics, and no product was uniformly superior. At the 100 mm/day threshold, the probability of detection ranged from 0.024 to 0.276, whereas the false alarm ratio ranged from 0.781 to 0.916. Upper-tail analysis showed contrasting product-specific behavior: at the 99th percentile, CHIRPS and GPM IMERG underestimated gauge rainfall by 20.95 and 8.95 mm, respectively, whereas GSMaP overestimated it by 35.57 mm. These findings demonstrate that local validation, uncertainty assessment, and application-specific adjustment are necessary before satellite precipitation products are used for flash-flood, rainfall-induced landslide, drainage-risk, and transportation-infrastructure assessments in mountainous regions.
Full article
(This article belongs to the Section Hydrology)
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Open AccessEditorial
Water-Induced Geo-Disaster Reduction in the Context of Climate Change: Hydrology, Management Strategies, and Ecological Geological Engineering
by
Chang Zhou
Water 2026, 18(15), 1921; https://doi.org/10.3390/w18151921 - 6 Aug 2026
Abstract
Extreme climate events are fundamentally altering the hydrological cycle at regional and global scales, intensifying the frequency and magnitude of geological hazards driven by water–rock interactions [...]
Full article
(This article belongs to the Special Issue Water-Induced Geo-Disaster Reduction in the Context of Climate Change: Hydrology, Management Strategies, and Ecological Geological Engineering)
Open AccessReview
Deep Learning for Remote Sensing-Based Surface Soil Moisture Monitoring and Prediction: A Review
by
Shengtao Yang, Wenbin Shao, Jing Wang and Dongying Zhang
Water 2026, 18(15), 1920; https://doi.org/10.3390/w18151920 - 6 Aug 2026
Abstract
Surface soil moisture (SM) is the keystone variable of terrestrial ecohydrology. Yet, the rapid diversification and development of deep learning architectures for satellite SM estimation have outpaced practitioners’ capacity to select among them. This review synthesizes 37 deep learning studies from the SMAP
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Surface soil moisture (SM) is the keystone variable of terrestrial ecohydrology. Yet, the rapid diversification and development of deep learning architectures for satellite SM estimation have outpaced practitioners’ capacity to select among them. This review synthesizes 37 deep learning studies from the SMAP era (2015–2026) across five architecture families (MLP and physics-informed neural networks [MLP/PINN], long short-term memory [LSTM] and gated recurrent unit [GRU] networks, convolutional neural networks [CNN], convolutional LSTM and graph neural networks [GNN], and Transformer-based models) to establish an architecture–task-matching framework that links each family to its dominant estimation niche. The analysis reveals consistent specializations: MLP/PINN models achieve competitive surface SM retrieval from satellite inputs; recurrent networks extend SMAP temporally (RMSE ≤ 0.035 ); CNN disaggregates SMAP to 1 km (reported unbiased root-mean-square error (ubRMSE) approaching 0.04 ); ConvLSTM and GNN address spatiotemporal gap-filling (low reported ubRMSE 0.022 ); and Transformers enable global multi-source fusion and decadal climate-scenario projection. Across all families, four physics-DL integration modes (hard architectural constraints, soft loss-function penalties, physics-as-input feature engineering, and physics-ML hybrid output fusion) consistently yield RMSE reductions of 8–50% relative to data-driven baselines. These findings provide a practitioner-oriented framework that is applicable to ecohydrological monitoring of plant water stress, agricultural drought, early flood warnings, and land–atmosphere coupling.
Full article
(This article belongs to the Special Issue Remote Sensing for Eco-Environmental Monitoring and Assessment in Agricultural Watersheds)
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Open AccessArticle
Preparation of Ho-Doped ZnO Powders by Sol–Gel and Hydrothermal Routes and Their Tribocatalytic Performance in Paracetamol Degradation
by
Stefani Petrova, Albena Bachvarova-Nedelcheva, Ralitsa Mladenova, Simona Delibaltova, Hristo Kolev and Nina Kaneva
Water 2026, 18(15), 1919; https://doi.org/10.3390/w18151919 - 6 Aug 2026
Abstract
In this study, pure ZnO and Ho-doped ZnO powders (1 and 2 mol % Ho) were synthesized via hydrothermal and sol–gel methods and evaluated for their tribocatalytic activity toward the degradation of paracetamol, an emerging pharmaceutical contaminant in aquatic environments. Structural, morphological, and
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In this study, pure ZnO and Ho-doped ZnO powders (1 and 2 mol % Ho) were synthesized via hydrothermal and sol–gel methods and evaluated for their tribocatalytic activity toward the degradation of paracetamol, an emerging pharmaceutical contaminant in aquatic environments. Structural, morphological, and optical properties of the obtained materials were investigated by X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. SEM observations revealed pronounced morphology differences between the synthesis routes, with hydrothermally prepared samples exhibiting well-defined rod-like structures. XPS and EPR analyses provided evidence for successful Ho modification of ZnO and the presence of defect-related electronic states associated with Ho doping. The tribocatalytic performance was examined in distilled, tap, and mineral water using friction rods with different geometries in order to assess the influence of synthesis route, Ho concentration, and water composition. Among all the investigated materials, hydrothermally synthesized ZnO doped with 2 mol % Ho exhibited the highest tribocatalytic activity, achieving 96.91% degradation of paracetamol at an initial concentration of 15 mg/L within 24 h. The enhanced performance was attributed to improved charge separation induced by Ho modification, combined with the favorable rod-like morphology of the particles. Higher degradation efficiencies were observed in distilled water compared to tap and mineral water, indicating the important role of dissolved ions during the tribocatalytic process. These findings demonstrate that the synthesis route, Ho doping, and water composition collectively govern the tribocatalytic performance of ZnO-based materials, highlighting their potential for water purification.
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(This article belongs to the Special Issue Data-Driven Optimization of Advanced Oxidation Processes for Water Harvesting Applications)
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Open AccessArticle
Integrating Multi-Temporal Land Use/Land Cover Dynamics into GALDIT-Based Seawater Intrusion Vulnerability Assessment for Sustainable Groundwater Management Along the Indian Coastline
by
Saravanan Subbarayan, Deepack Ezhilarasu, Sivaranjani Sivalingam, Bojan Đurin, Kaliraj Seenipandi, Ehab Gomaa, Youssef M. Youssef and Mahmoud E. Abd-Elmaboud
Water 2026, 18(15), 1918; https://doi.org/10.3390/w18151918 - 6 Aug 2026
Abstract
Seawater intrusion (SWI) represents an increasingly critical challenge for coastal groundwater systems, with particularly pronounced impacts observed along the Indian coastline. Coastal aquifers constitute a vital freshwater resource supporting domestic, agricultural, and industrial demands. This study evaluates SWI vulnerability along the entire Indian
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Seawater intrusion (SWI) represents an increasingly critical challenge for coastal groundwater systems, with particularly pronounced impacts observed along the Indian coastline. Coastal aquifers constitute a vital freshwater resource supporting domestic, agricultural, and industrial demands. This study evaluates SWI vulnerability along the entire Indian coast, extending from Gujarat to West Bengal, covering approximately 7517 km of shoreline and up to 100 km inland. The assessment applies the GALDIT vulnerability framework that combines several hydrogeological and hydrochemical criteria such as groundwater occurrence, aquifer hydraulic conductivity, depth to groundwater, distance from shoreline, hydrochemical data, and groundwater quality data. We also assessed the intrusion of existing seawater, shoreline location, and aquifer thickness. However, conventional vulnerability assessments are inherently static and often fail to capture anthropogenic influences. To address this limitation, the present study integrates multi-temporal land use and land cover (LULC) datasets derived from ESA WorldCover remote sensing data for the period 2017–2024. Incorporating LULC dynamics enables a more comprehensive evaluation of the impacts of urban expansion and agricultural intensification on coastal susceptibility to SWI. Accordingly, a modified GALDIT-LU framework is developed to assess the spatiotemporal evolution of coastal vulnerability. The outcomes suggest that huge parts of the Indian coastline are vulnerable to moderate or very high classes, with the very high vulnerability class growing from 13,295 km2 in 2017 to 38,257 km2 in 2024, a 188% increase in vulnerability over the course of seven years. Groundwater chloride concentrations from Central Ground Water Board (CGWB) monitoring well locations have been used for validation over the proposed assessment, and show good spatial agreement between areas identified as high vulnerability and the spatial distribution of groundwater salinity for all three assessment periods, lending support to the robustness and predictive power of the proposed groundwater salinity assessment. The findings carry direct implications for the United Nations 2030 Agenda, demonstrating that the identified vulnerability patterns intersect with critical targets related to clean water and sanitation, food security, public health, climate action, and poverty reduction along one of the world’s most densely populated coastlines.
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(This article belongs to the Special Issue Advances in Hydrogeological Investigations: Field Monitoring, GIS, AI, Remote Sensing, Geophysical Techniques, and Hydrochemical Analysis)
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Open AccessArticle
Satellite-Derived Chlorophyll-a Phenology and Recurrent High-Chl-a Exceedance Screening in Fujian Coastal Bays, China
by
Dongren Li, Boming Zhou, Jiayuan Fu, Guoye Zhao, Xiaohe Lai, Yan Su, Chuan Lin and Xiudong Xie
Water 2026, 18(15), 1917; https://doi.org/10.3390/w18151917 - 5 Aug 2026
Abstract
Long-term chlorophyll-a (Chl-a) phenology and recurrent high-Chl-a conditions provide important evidence for identifying spatially persistent water-quality concerns in coastal bays. However, seasonally normalized screening of high-Chl-a recurrence at the sampling-cell scale remains limited for subtropical multi-bay coastlines, where
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Long-term chlorophyll-a (Chl-a) phenology and recurrent high-Chl-a conditions provide important evidence for identifying spatially persistent water-quality concerns in coastal bays. However, seasonally normalized screening of high-Chl-a recurrence at the sampling-cell scale remains limited for subtropical multi-bay coastlines, where regional monsoon forcing, hydrodynamic retention, riverine inputs, aquaculture, and coastal development jointly shape phytoplankton variability. Based on Copernicus Marine ocean-colour records from 2003 to 2024, this study developed a reproducible ~4 km sampling-cell framework for seven coastal bays in Fujian, China. Monthly geometric-mean climatologies, phenological metrics, P90-based high-Chl-a exceedance frequencies, monitoring-priority classes, and exploratory machine-learning diagnostics were derived. Bay-scale phenology showed clear divergence: Sansha and Xinghua Bays exhibited winter or year-end Chl-a enhancement, Xiamen Bay peaked in summer, and Quanzhou Bay reached an early-autumn maximum. Four seasonal phenological regimes further revealed cell-scale heterogeneity, with C2 representing winter-enhanced, high-amplitude cycles and C3 identifying cells with the most frequent seasonally normalized high-Chl-a exceedances. High- and moderate-priority cells were concentrated mainly in Sansha and Xinghua Bays, whereas Dongshan and Quanzhou Bays showed only localized priority cells. Exploratory diagnostics indicated that distance to the bay mouth was the most important correlate of recurrent high-Chl-a susceptibility, suggesting the role of bay-scale exchange and retention gradients. This framework converts long-term ocean-colour archives into spatially explicit phenological and anomaly-screening evidence to support targeted coastal water-quality monitoring and ecosystem management.
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(This article belongs to the Special Issue Pollution Process and Microbial Responses in Aquatic Environment)
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Open AccessArticle
A Portable Hand-Operated Reverse Osmosis Desalination Device with Integrated Hydraulic Brine Energy Recovery
by
Zhenxiang Su, Fanglong Yin and Yongmao Hao
Water 2026, 18(15), 1916; https://doi.org/10.3390/w18151916 - 5 Aug 2026
Abstract
Securing a freshwater supply for personnel engaged in remote maritime operations remains a persistent logistical challenge. This paper presents the design, hydraulic simulation, and experimental validation of a compact, manually operated seawater desalination device based on reverse osmosis (RO) coupled with an integrated
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Securing a freshwater supply for personnel engaged in remote maritime operations remains a persistent logistical challenge. This paper presents the design, hydraulic simulation, and experimental validation of a compact, manually operated seawater desalination device based on reverse osmosis (RO) coupled with an integrated hydraulic energy recovery system. The device employs a valve-commutated piston pump (cylinder bore 6 mm, rod diameter 3.7 mm, stroke 70 mm) driven by a lever-type handle mechanism. High-pressure brine rejected by the RO membrane is redirected via a two-position, three-way directional valve into the rod-end cavity of the pump cylinder, partially offsetting the filtration resistance and achieving an energy recovery ratio of 49.5%. Hydraulic circuit dynamics were analyzed using AMESim software, yielding a simulated freshwater output of approximately 0.02 L/min (1.2 L/h). A functional prototype with overall dimensions of 200 × 128 × 63 mm was fabricated and tested under 3.57% salinity conditions. Five consecutive trials produced a mean freshwater flow rate of approximately 1.15 L/h (desalination rate exceeding 95%), confirming consistency with the simulation predictions and satisfying the design requirements for individual field use in remote maritime settings.
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(This article belongs to the Special Issue Advances in Sustainable Water Resources Management and Water–Energy Nexus)
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Open AccessArticle
Transforming Water Supplies in the Midwest: Two CBAT Pilots Demonstrate the Potential for Water Reuse
by
Josh Fuchs, Shannon Thayer, Philip MacClellan, Gayathri Ram Mohan and Kati Bell
Water 2026, 18(15), 1915; https://doi.org/10.3390/w18151915 - 5 Aug 2026
Abstract
Population growth, increasing water demands for data centers, and the need for more sustainable water practices are prompting advancement of next-generation water resource management strategies including water reuse. In the Midwestern United States (U.S.), where non-traditional approaches to augmenting water supply, including water
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Population growth, increasing water demands for data centers, and the need for more sustainable water practices are prompting advancement of next-generation water resource management strategies including water reuse. In the Midwestern United States (U.S.), where non-traditional approaches to augmenting water supply, including water reuse, are relatively new, full advanced water treatment (AWT), which includes microfiltration/ultrafiltration (MF/UF) and reverse osmosis (RO), produces a concentrate stream that is expensive to address (i.e., brine disposal). Carbon-based advanced treatment (CBAT), which combines ozonation, biofiltration, and granular activated carbon, has been shown to be a viable alternative with select advantages over the traditional RO approach, including the lack of brine generation. Two novel pilots were conducted in the Midwestern U.S., one at a large (>100 MGD) and one at a small (~10 MGD) wastewater reclamation facility (WRF), to provide proof of concept that CBAT could meet distinct regional needs. While additional demonstration data are ultimately needed for future regulatory approvals, results from the pilots showed that water quality objectives were met with treated water quality of <0.5 mg/L total Kjeldal nitrogen (TKN), <2 mg/L total organic carbon (TOC), and substantial reduction in constituents of emerging concern (CECs). If nitrate removal is required to meet drinking water standards (10 mg/L), additional treatment optimization at the source WRFs would be required. Areas for further research identified by this effort include mitigating the potential for ozonation to contribute to the formation of disinfection byproducts such as bromate and N-nitrosodimethylamine (NDMA). Along with the treatment performance demonstrated at these pilots, the study provided an opportunity to engage with key stakeholders to build trust in the AWT approach, which is critically important for regulatory and public acceptance. Based on two field-scale pilot studies in the U.S. Midwest, this paper analyzes CBAT application advantages and challenges in municipal water reuse and identifies research directions for the industry.
Full article
(This article belongs to the Special Issue Drawbacks, Limitations, Solutions and Perspectives of Water Reuse)
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