Water

14 pages, 3304 KB

Open AccessArticle

Influence of Blade Tip Clearance on External Characteristics and Internal Flow Pattern of Axial Flow Pumps

by Ling Bai, Jie Zhang, Lei Jiang, Hong Xu and Ling Zhou

Water 2026, 18(3), 437; https://doi.org/10.3390/w18030437 - 6 Feb 2026

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Axial flow pumps, widely utilized in critical fields such as agricultural irrigation, urban water diversion and flood control, play an indispensable role in large-scale water transport and drainage projects due to their high-flow and low-head characteristics. This study systematically investigates the influence of [...] Read more.

Axial flow pumps, widely utilized in critical fields such as agricultural irrigation, urban water diversion and flood control, play an indispensable role in large-scale water transport and drainage projects due to their high-flow and low-head characteristics. This study systematically investigates the influence of tip clearance on the external characteristics and internal flow field of a large-scale axial flow pump (model 1800GZX-125). By combining numerical simulations with experimental validation, a comparative analysis was conducted under four tip clearance sizes (3 mm, 12 mm, 17.5 mm, 24 mm) and various flow conditions. The results indicate that increasing the tip clearance generally reduces the pump head and peak efficiency. It also alters the blade pressure distribution, expands the low-pressure region, and intensifies tip leakage flow. While vorticity overall increases, it weakens locally under certain conditions due to changes in leakage flow patterns. Entropy generation analysis further reveals that larger clearances lead to significantly increased energy losses, thereby degrading external performance. These findings provide a theoretical basis for improving the performance and operational stability of axial flow pumps. Full article

(This article belongs to the Special Issue Hydrodynamics in Pumping and Hydropower Systems, 2nd Edition)

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21 pages, 4464 KB

Open AccessArticle

Future Climate Change Increases Streamflow and Risks of Hydrological Hazards in the Pearl River Basin

by Haoyuan Yu, Qichun Yang, Liuqian Yu, Xia Li, Minyang Li and Yingxian Yang

Water 2026, 18(3), 436; https://doi.org/10.3390/w18030436 - 6 Feb 2026

Viewed by 1372

Abstract

Understanding and predicting climate change impacts on the terrestrial water cycle is essential for water resources management and hazard prevention. This study aims to project future runoff of a densely-populated river basin, the Pearl River Basin (PRB), under different Shared Socioeconomic Pahway (SSP) [...] Read more.

Understanding and predicting climate change impacts on the terrestrial water cycle is essential for water resources management and hazard prevention. This study aims to project future runoff of a densely-populated river basin, the Pearl River Basin (PRB), under different Shared Socioeconomic Pahway (SSP) scenarios, by combining the Soil and Water Assessment Tool (SWAT) model and the CMIP6 climate projections. Results show that climate change will significantly increase the runoff of the PRB, with changing rates of 0.21, 0.20, 0.11, and 0.17 mm/month/year for low- to high-emission scenarios SSP126, SSP245, SSP370, and SSP585, respectively. Future runoff exhibits strong seasonal and spatial variability due to complex changes in precipitation and potential evapotranspiration across the basin. The PRB may experience higher flood risks during the wet season under all SSP scenarios, driven by a ~15% increase in runoff during the wettest month during 2061–2100 relative to that of 2021–2060. Conversely, drought risks may escalate in the East River Sub-basin of the PRB during the dry season under the high-emission scenarios (SSP370 and SSP585), with a ~20% reduction in runoff during the driest month during 2061–2100 relative to that of 2021–2060. The highest-emission scenario (SSP585) may lead to the most drastic hydrological changes, including increased risks of flooding and drought across different parts of the PRB. Our findings suggest intensified water cycling and increased hydrological risks in the PRB under a changing climate, highlighting the necessity of future water resource management to consider potential climate change impacts to mitigate the risks of floods and droughts effectively. Full article

(This article belongs to the Special Issue Using Hydrological Modeling for Spatio-Temporal Analysis of Rainfall Signatures)

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12 pages, 1821 KB

Open AccessArticle

Impact of Food Processing Industry Wastewater on Root Growth and DNA Damage in Allium cepa L. as Assessed by the Comet Assay

by Matiba Tufail, Muhammad Luqman, Zahid Mehmood, Wasim Abbas, Maryam Iqbal, Harma Shah, Imran Farooq Awan, Noor Sana, Arooba John, Samra Rafiq, Awais Riaz, Adeel Ahmad, Anum Tahir and Muhammad Umer Farooq Awan

Water 2026, 18(3), 435; https://doi.org/10.3390/w18030435 - 6 Feb 2026

Cited by 1 | Viewed by 780

Abstract

Wastewater from food processing industries contains synthetic dyes and preservatives that may pose phytotoxic and genotoxic risks. The present work represents an exploratory study based on a wastewater source and sampling period. Wastewater was characterized by physicochemical analysis and high-performance liquid chromatography (HPLC). [...] Read more.

Wastewater from food processing industries contains synthetic dyes and preservatives that may pose phytotoxic and genotoxic risks. The present work represents an exploratory study based on a wastewater source and sampling period. Wastewater was characterized by physicochemical analysis and high-performance liquid chromatography (HPLC). Onion seeds and bulbs were exposed to 0% (control), 20%, 40%, 60%, 80%, and 100% wastewater dilution. DNA was extracted from root cells using the cetyltrimethylammonium bromide (CTAB) method. The DNA damage was analyzed by the comet assay. HPLC analysis confirmed the presence of sorbic acid, citric acid, benzoic acid, butylated hydroxyanisole (BHA), and butylated Hydroxytoluene (BHT) by showing corresponding peaks. The mean root length in wastewater was significantly reduced by 55%, 50%, and 65% on days 3, 5, and 7, respectively, relative to the control. On day 3, the highest genotoxicity at 100% wastewater was indicated by 96.69% tail DNA, a tail moment of 108.3 a.u., an Olive tail moment of 58.01 a.u., and a comet length of 136 µm. Enhanced DNA damage persisted on days 5 and 7, with comet lengths reaching 127–149 µm and 111–182 µm, respectively. Although the observed effects may reflect general cytotoxicity arising from a complex wastewater mixture and showed that untreated food processing wastewater presents a significant genotoxic risk and requires effective treatment prior to reuse. Full article

(This article belongs to the Special Issue Advances and Innovations in Technologies for Treatment and Toxicity Assessment of Conventional and Emerging Contaminant in Industrial Wastewater)

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20 pages, 1330 KB

Open AccessArticle

Constraint-Aware and Economic Optimization of Riverbank Retaining Walls Using Metaheuristic Algorithms

by Shaymaa Alsamia, Edina Koch and Mais Mayassah

Water 2026, 18(3), 434; https://doi.org/10.3390/w18030434 - 6 Feb 2026

Viewed by 478

Abstract

The optimal design of riverbank retaining walls requires a careful balance between structural safety, constructability, and economic efficiency. In this study, a constraint-aware optimization framework is developed for the design of concrete gravity retaining walls by explicitly incorporating stability, serviceability, and geometric feasibility [...] Read more.

The optimal design of riverbank retaining walls requires a careful balance between structural safety, constructability, and economic efficiency. In this study, a constraint-aware optimization framework is developed for the design of concrete gravity retaining walls by explicitly incorporating stability, serviceability, and geometric feasibility constraints. Several metaheuristic algorithms are comparatively evaluated under identical computational conditions using 30 independent runs, a population size of 50, and 1000 iterations. The results demonstrate that enforcing geometric constraints is essential to prevent non-physical designs and to ensure engineering realism. Quantitative analysis shows that the Flower Fertilization Optimization (FFO) algorithm yields the minimum wall weight, reducing material usage by approximately 19% compared to more conservative solutions. In contrast, the adaptive exploration artificial bee colony (AEABC) algorithm exhibits the most robust and repeatable convergence behavior with low statistical dispersion across independent runs. An economic assessment based on concrete volume further confirms the direct impact of material efficiency on construction cost. The proposed framework highlights the importance of constraint-aware optimization for achieving reliable and economically efficient retaining wall designs. Full article

(This article belongs to the Section New Sensors, New Technologies and Machine Learning in Water Sciences)

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20 pages, 1239 KB

Open AccessArticle

Sustainable Selection Criteria for Small Wastewater Treatment Plants Ensuring Biodegradation

by Zbigniew Mucha, Agnieszka Generowicz, Kamil Zieliński, Iga Pietrucha, Anna Kochanek, Piotr Herbut, Paweł Kwaśnicki, Anna Gronba-Chyła and Elżbieta Sobiecka

Water 2026, 18(3), 433; https://doi.org/10.3390/w18030433 - 6 Feb 2026

Viewed by 1024

Abstract

The rapid development of rural and peri-urban areas increases the demand for decentralized wastewater treatment systems. Small wastewater treatment plants (SWTPs) with a capacity below 2000 PE are becoming an important element of local water protection and circular-economy strategies, yet clear guidelines for [...] Read more.

The rapid development of rural and peri-urban areas increases the demand for decentralized wastewater treatment systems. Small wastewater treatment plants (SWTPs) with a capacity below 2000 PE are becoming an important element of local water protection and circular-economy strategies, yet clear guidelines for selecting appropriate technologies are still lacking. This study analyzes the criteria used in decision-making for SWTPs from a multi-stakeholder perspective and evaluates the relative importance of technical, economic, environmental and social factors. The research was conducted in Poland and included a survey of 130 respondents representing six stakeholder groups (officials, operators, designers, contractors, scientists and residents). Respondents allocated weights to four main groups of criteria and assessed eleven detailed parameters on a 1–10 scale. The data were analyzed using descriptive statistics, the Kolmogorov–Smirnov test with the Lilliefors correction to verify distribution assumptions, and the Kruskal–Wallis test to examine differences between stakeholder groups. The results show a consistent hierarchy of criteria, with technical reliability, treatment efficiency and operating costs ranked as the most important factors. Social and environmental aspects were assessed as relevant but secondary. Only minor differences between stakeholder groups were observed. The study highlights the need for integrated, multicriteria approaches in SWTP planning, particularly in dispersed rural areas. The findings may support local authorities, designers and investors in technology selection. The research is limited by the non-probability sampling strategy, the national scope of the dataset and the cross-sectional character of the survey. Full article

(This article belongs to the Special Issue Sustainable Biodegradation and Bioremediation of Organic Contaminants in Aquatic and Terrestrial Environments)

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19 pages, 38597 KB

Open AccessArticle

Hydraulic Characteristics and the Adaptability to Water-Level Fluctuation of the Vertical-Slot Fishway

by Xianglong Huang, Junjun Tan, Yuanyang Wang, Junjian Sun, Sicheng Zeng, Shuaijie Wu and Xiaotao Shi

Water 2026, 18(3), 432; https://doi.org/10.3390/w18030432 - 6 Feb 2026

Viewed by 714

Abstract

This study explored the hydraulic characteristics and the adaptability to water-level fluctuations of the vertical-slot fishway. The maximum allowable water depth difference between the entrance and exit was calculated for a one-entrance fishway and two-entrance fishways with different entrance distances (100 m, 200 [...] Read more.

This study explored the hydraulic characteristics and the adaptability to water-level fluctuations of the vertical-slot fishway. The maximum allowable water depth difference between the entrance and exit was calculated for a one-entrance fishway and two-entrance fishways with different entrance distances (100 m, 200 m, 300 m) under insufficient entrance water depth, with a fishway slope of 2% and an exit water depth of 2.5 m. It was found that the maximum allowable water depth difference between the 1# entrance and exit of the two-entrance fishways (0.71 m, 0.85 m, 0.93 m) was greatly larger than that of the one-entrance fishway (0.48 m). Additionally, the maximum allowable water depth difference in the two-entrance fishway increased with the increased distance between the two entrances. The relationship between the maximum allowable water depth difference and the distance of the two entrances followed a logarithmic function. We suggested that the 2# entrance should be at least 1.6 m when the water depth of 1# entrance was decreased to 1.8 m. When the water depth of the 1# entrance was gradually decreased to 1.6 m, the water depth of the 2# entrance also gradually decreased to 1.2 m. The distance between the 1# entrance and 2# entrance subsequently changed. It was noteworthy that the conclusions proposed in this study were strictly limited to vertical-slot fishways with a slope of 2%, exit water depth of 2.5 m, similar geometric parameters, and target cyprinid species. Furthermore, different slopes or exit water depths should be studied to extend the relationship by introducing correction coefficients from subsequent studies. This study can provide references for the design and optimization of future fishway projects. Full article

(This article belongs to the Special Issue Ecohydraulics and Fish Behavior Simulation)

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14 pages, 2037 KB

Open AccessArticle

Turbulence in a Bend in the Presence of Emergent Vegetation and a 3D Pool Bedform

by Alirahm Rahimpour, Hossein Afzalimehr, Saeid Okhravi, Mohammad Nazari-Sharabian and Moses Karakouzian

Water 2026, 18(3), 431; https://doi.org/10.3390/w18030431 - 6 Feb 2026

Cited by 1 | Viewed by 599

Abstract

The interaction of emergent vegetation and three-dimensional (3D) bedforms is essential for understanding turbulent flow dynamics in curved channels. A laboratory investigation can help to collect required data under controlled conditions. Experiments were conducted in a 9.5 m-long, 0.9 m-wide recirculating flume incorporating [...] Read more.

The interaction of emergent vegetation and three-dimensional (3D) bedforms is essential for understanding turbulent flow dynamics in curved channels. A laboratory investigation can help to collect required data under controlled conditions. Experiments were conducted in a 9.5 m-long, 0.9 m-wide recirculating flume incorporating a 90° bend and a sculpted 3D pool bedform. Artificial rigid vegetation, designed to replicate the hydraulic behavior of natural emergent plants, was installed along both sidewalls. Instantaneous three-dimensional velocities were recorded using an acoustic Doppler velocimeter (ADV) across multiple cross-sections under both bare-bed and vegetated conditions. The results reveal that emergent vegetation markedly increases flow resistance, distorts mean velocity distributions, and suppresses the classical logarithmic velocity profile, particularly within the bend and pool regions. The combined presence of vegetation and the 3D pool bedform amplified turbulence intensity, elevated Reynolds shear stresses, and redistributed turbulent kinetic energy (TKE), which increased by up to sevenfold from the bend entrance to its exit. In vegetated pool sections, Reynolds stresses were approximately 12% greater than under bare-bed conditions, underscoring the synergistic effects of vegetation drag, secondary circulation, and flow separation in producing anisotropic turbulence. These findings highlight the importance of incorporating vegetation–bedform interactions in fluvial modeling frameworks, with significant implications for sediment transport prediction, channel stability evaluation, river restoration, and aquatic habitat design. Full article

(This article belongs to the Special Issue Advancing Hydro-Environmental Research and Practice: Integrating Ecohydrology, Remote Sensing and Hydroinformatics)

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19 pages, 14930 KB

Open AccessArticle

Understanding Spatiotemporal Inundation Dynamics in the Sundarbans Mangroves Through Hydrodynamic Modelling

by Fazlul Karim, Shaikh Nahiduzzaman, Raju Ahmmad, Mohammed Mainuddin, Shahriar Wahid and Rubayat Alam

Water 2026, 18(3), 430; https://doi.org/10.3390/w18030430 - 6 Feb 2026

Viewed by 805

Abstract

Tidal inundation plays a critical role in maintaining the ecosystem services of the Sundarbans mangrove forest. In this study, we configured and calibrated a coupled one-dimensional (1D) river network and two-dimensional (2D) floodplain hydrodynamic model for the Sundarbans in Bangladesh. Model calibration was [...] Read more.

Tidal inundation plays a critical role in maintaining the ecosystem services of the Sundarbans mangrove forest. In this study, we configured and calibrated a coupled one-dimensional (1D) river network and two-dimensional (2D) floodplain hydrodynamic model for the Sundarbans in Bangladesh. Model calibration was performed using gauged water levels, inundation maps, and Google Earth (Version 7.3.6) imagery. Using the calibrated model, we assessed potential changes in inundation extent, depth, and duration across the Sundarbans for varying freshwater inflow and tidal height scenarios. Results show variation in inundation extent, depth, and duration spatially and temporarily across the Sundarbans. Inundation is relatively less during February-March (end of the dry season) and high in July-August (mid-wet season). Approximately 3158 km² (85.1%) of the Sundarbans experiences at least one inundation in March, increasing to about 3658 km² (98.6%) in July. Although a large proportion of the Sundarbans inundate during daily tidal cycles, the mean inundation depth remains shallow (0.24 to 0.33 m) due to flat topography. The influence of freshwater inflow on inundations is small (<2%). In contrast, the impacts of tidal magnitude are substantial on both inundation extent and depth. These findings provide valuable insights on inundation dynamics for understanding the hydrological and ecological functioning of the Sundarbans. Full article

(This article belongs to the Special Issue Flood Inundation Modeling and Mapping: Application of Hydrodynamic Models, Remote Sensing and Machine Learning Tools)

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20 pages, 4107 KB

Open AccessArticle

Analysis of Contaminant Behavior in Loop Pipe System for Ultrapure Water Distribution Using Computational Fluid Dynamics and Autopsy

by Juyoung Andrea Lee, Jinsu Park, Song Lee, Kyunghyun Son and Sangho Lee

Water 2026, 18(3), 429; https://doi.org/10.3390/w18030429 - 6 Feb 2026

Viewed by 878

Abstract

Ultrapure water (UPW) distribution loops must deliver stable hydraulics while limiting contamination from polymer piping. This study integrates computational fluid dynamics (CFD) with systematic pipe autopsy to examine contaminant behavior in a pilot-scale UPW loop constructed using chlorinated polyvinyl chloride (CPVC) and polyvinylidene [...] Read more.

Ultrapure water (UPW) distribution loops must deliver stable hydraulics while limiting contamination from polymer piping. This study integrates computational fluid dynamics (CFD) with systematic pipe autopsy to examine contaminant behavior in a pilot-scale UPW loop constructed using chlorinated polyvinyl chloride (CPVC) and polyvinylidene fluoride (PVDF) and operated under identical conditions. CFD predicted nearly identical loop-scale velocity, pressure, and temperature fields for both materials, and identified low-shear recirculation at elbows and downstream tees as zones of elevated particle residence. Lagrangian particle tracking (0.05 μm, no-sticking) showed rapid breakthrough and complete flushing within 13 min, providing a hydraulic susceptibility map for transient retention. After eight months of operation, 17 sections were inspected endoscopically and leached at 60 °C. CPVC exhibited yellow–brown discoloration and highly heterogeneous total organic carbon (TOC) release with hot spots of 16–18 mg·L⁻¹, whereas PVDF showed low, spatially uniform TOC (0.4–2.3 mg·L⁻¹) and minimal fouling; inorganic ions remained at sub-mg·L⁻¹ levels for both materials. Overall, geometry governs where contamination can accumulate, while material properties control its magnitude and persistence, with PVDF providing greater resistance to long-term organic contamination than CPVC. Full article

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

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5 pages, 151 KB

Open AccessEditorial

Integrated Approaches to Water Resources and Environmental Management: Innovations in Simulation and Impact Assessment

by Yuntao Wang

Water 2026, 18(3), 428; https://doi.org/10.3390/w18030428 - 6 Feb 2026

Viewed by 389

Abstract

Water resources and environmental systems face unprecedented pressure from the combined effects of climate change, rapid urbanization, population growth, land-use transformation, and intensifying economic activities [...] Full article

(This article belongs to the Special Issue Integrated Approaches to Water Resources and Environmental Management: Innovations in Simulation and Impact Assessment)

19 pages, 4029 KB

Open AccessArticle

Smart Technological Urban Flood Management Strategies Are “Must-Do” Approaches: The Case of Chinese Coastal Megacity, Ningbo, East Coast of China

by Faith Ka Shun Chan, Weiwei Gu, Fang Zhang, Xiaolei Pei, Zilin Wang, Lingwen Lu, Ming Cheng, Yuhe Wang, Weiguo Zhang and Yutian Jiang

Water 2026, 18(3), 427; https://doi.org/10.3390/w18030427 - 6 Feb 2026

Viewed by 1350

Abstract

Ningbo (NGB), a major port city on China’s east coast, is defined by a network of over 100 rivers across three major catchments. From the 1970s to the 2000s, extensive engineering, including channelisation and embankment construction, was used to manage flood risk during [...] Read more.

Ningbo (NGB), a major port city on China’s east coast, is defined by a network of over 100 rivers across three major catchments. From the 1970s to the 2000s, extensive engineering, including channelisation and embankment construction, was used to manage flood risk during rapid urbanisation. Since the 2010s, however, the city has shifted towards smart flood management. The Ningbo government and Water Bureau have deployed digital twins and technologies like 3D flood mapping and real-time monitoring, significantly improving precision. Our study demonstrated that this smart technology performed effectively during recent extreme events, namely typhoons In-Fa (2021) and Muifa (2022), helping the Municipal Bureau to safeguard public safety. This success strengthens municipal and national commitments to climate resilience. Nevertheless, further advancement of the digital twin platform is required. Key priorities include boosting computational capacity, improving cross-departmental coordination, establishing open data sharing, and integrating artificial intelligence (AI) to enhance decision-making during future climate extremes. Full article

(This article belongs to the Special Issue Water Reuse and Land Management: Strategies, Policies, and Integrated Land-Use Approaches)

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13 pages, 925 KB

Open AccessReview

Marine Pollution in Panama: A Bibliometric Approach to Knowledge Gaps and Institutional Influence

by Nelva E. Alvarado-González, Yulissa De Gracia, Jenifer Ortega, Maricselis Díaz, Yostin Añino, Xabier Lekube, Maren Ortiz-Zarragoitia and Beñat Zaldibar

Water 2026, 18(3), 426; https://doi.org/10.3390/w18030426 - 6 Feb 2026

Viewed by 1017

Abstract

Human activities in Panama, such as agriculture, industry, and transport, have led to the release of pollutants that affect the health of marine and coastal ecosystems. However, there is a lack of bibliographic compilation studies to understand the current state of research on [...] Read more.

Human activities in Panama, such as agriculture, industry, and transport, have led to the release of pollutants that affect the health of marine and coastal ecosystems. However, there is a lack of bibliographic compilation studies to understand the current state of research on marine pollution in Panama. In recent years, bibliometric studies have attracted attention due to the development of new analytical and integrative online tools. This study conducts a bibliometric analysis of marine pollution and its environmental effects on Panama’s coastal areas. The results show consistent growth in scientific production, with increased collaboration among researchers. However, the involvement of national institutions is limited, highlighting the need to strengthen local research. Most publications focus on environmental sciences, with a recent shift towards studying a broader range of pollutants. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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12 pages, 1789 KB

Open AccessArticle

Tritium and Plutonium Time Series from the Puruogangri Ice Field, Tibetan Plateau, China

by László Palcsu, Miruna Cotan, Lide Tian, Cheng Wang, Liu Feng, Xu Chenhao, Yu Songlin, Magdolna Szilágyi, Loránd Zákány, Zoltán Dezső, Danny Vargas and Marjan Temovski

Water 2026, 18(3), 425; https://doi.org/10.3390/w18030425 - 5 Feb 2026

Viewed by 895

Abstract

Ice cores retrieved from the Third Pole provide invaluable information about past and present environmental changes. Here we present, for the first time, a continuous tritium and plutonium isotope profile of the Puruogangri ice field, Tibetan Plateau, China, for the last 70 years. [...] Read more.

Ice cores retrieved from the Third Pole provide invaluable information about past and present environmental changes. Here we present, for the first time, a continuous tritium and plutonium isotope profile of the Puruogangri ice field, Tibetan Plateau, China, for the last 70 years. The age-depth profile has been composed by different time anchors such as the onset of thermonuclear weapon tests, the so-called bomb peak of tritium, the Chernobyl event, and the time of ice coring. The accumulation rate of ice calculated from the age-depth relation shows a decrease after 1963. It was 57, 15, and 22 cm/year in the periods of 1954–1963, 1963–1986, and 1986–2023, respectively. The concentrations of plutonium isotopes (²³⁹Pu: up to 2.7 fg/g) are slightly lower than those of the Belukha ice core, Siberian Altai, Russia, and almost the same as the Miaoergou glacier, eastern Tien Shan, China. Contrary to this latter ice core profile, the Puruogangri plutonium profile reflects that the Chinese weapon test started in 1966. This is confirmed by the tritium time series as well. ²⁴⁰Pu/²³⁹Pu atomic ratios vary between 0.14 and 0.23, with an average of 0.177 ± 0.024. The overall obtained local fallout of ²³⁹Pu and ²⁴⁰Pu is 13.2 and 9.0 Bq/m² (4.0 and 1.1 ng/m²), respectively. Full article

(This article belongs to the Section Water and Climate Change)

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27 pages, 3345 KB

Open AccessArticle

Distributive Disturbances: Examining Community Exposure to Drinking Water Contaminants Amidst the Jackson, Mississippi (USA) Water Crisis

by Ambria N. McDonald, Yolanda J. McDonald, Andrea Chow, Julia Kosinski and Dorceta E. Taylor

Water 2026, 18(3), 424; https://doi.org/10.3390/w18030424 - 5 Feb 2026

Viewed by 1723

Abstract

Community water systems in the United States provide drinking water to more than 300 million people annually, making their reliability fundamental to public health. In regions with long histories of racial segregation and unequal infrastructure maintenance, water system failures can deepen existing environmental [...] Read more.

Community water systems in the United States provide drinking water to more than 300 million people annually, making their reliability fundamental to public health. In regions with long histories of racial segregation and unequal infrastructure maintenance, water system failures can deepen existing environmental injustices. This study examines water quality conditions in the Jackson, Mississippi, metropolitan area following the 2022 distribution system collapse and a decade of repeated noncompliance with the Safe Drinking Water Act’s Lead and Copper Rule (LCR). Using the U.S. Environmental Protection Agency’s 2024 updated LCR tap sampling protocol, water samples from 29 sites were collected. Samples were analyzed for lead, copper, iron, zinc, chlorine, sulfate, pH, and total dissolved solids concentrations. Chlorine-to-sulfate mass ratios (CSMR) were also calculated to evaluate corrosion potential. Demographic surveys, statistical analyses, and geospatial visualizations were used to interpret neighborhood-level patterns. Our findings show that all sites met primary drinking water standards and complied with LCR action levels but exceeded secondary drinking water standards at 100% of study sites. Seven sites exhibited CSMR values above the threshold, indicating increased susceptibility to corrosion. These results highlight the need for targeted corrosion control, treatment optimization, and ongoing monitoring, particularly in historically marginalized communities. Full article

(This article belongs to the Special Issue Spatial Linkages Between Geographical Environments and Health Indicators: From Water Quality Parameters to Regional Health Status)

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18 pages, 5522 KB

Open AccessArticle

A Study on the Hydrogen and Oxygen Stable Isotope Characteristics of Water in Small Watersheds on the Southern Slope of the Qilian Mountains

by Qixin He, Guangchao Cao, Guangzhao Han, Meiliang Zhao, Jiaqi Bai and Wenqian Ye

Water 2026, 18(3), 423; https://doi.org/10.3390/w18030423 - 5 Feb 2026

Cited by 1 | Viewed by 782

Abstract

This study, based on stable hydrogen and oxygen isotope observations of multiple water bodies (precipitation, river water, soil water, and groundwater) in the Ami Dongsou alpine arid watershed on the southern slope of the Qilian Mountains during 2023–2024, reveals significant seasonal fluctuations in [...] Read more.

This study, based on stable hydrogen and oxygen isotope observations of multiple water bodies (precipitation, river water, soil water, and groundwater) in the Ami Dongsou alpine arid watershed on the southern slope of the Qilian Mountains during 2023–2024, reveals significant seasonal fluctuations in water isotope characteristics and water source renewal mechanisms. The results show that precipitation and soil water exhibit notable enrichment during the dry season, primarily due to enhanced evaporation causing light isotopes to evaporate and heavy isotopes to accumulate. River water, influenced by both precipitation recharge and evaporation, shows smaller seasonal fluctuations. Groundwater isotopes remain stable, reflecting a slower water source renewal process with minimal seasonal influence. Through quantitative comparisons of the evaporation line’s slope and intercept, this study finds that precipitation is most significantly affected by evaporation, while groundwater is least influenced, showing more stable isotope characteristics. Climate and topography in high-altitude areas significantly regulate water isotope characteristics, especially during the dry season, where evaporation plays a dominant role in the enrichment of precipitation and river water isotopes. This study innovatively establishes an evidence framework for the linkage of multiple water body isotopes, revealing the “seasonal strong fluctuations + differential water body responses + high-altitude regulation” mechanism of water isotopes in alpine arid regions. It provides new data support for water resource management, particularly in aspects such as water source allocation during the dry season, groundwater protection, and evaporation enrichment effect prediction. Future research could expand the sample size and integrate multi-source data and hydrological models to further improve the accuracy of hydrological process predictions, offering more precise support for watershed water resource management and ecological protection. Full article

(This article belongs to the Special Issue Applications of Stable Isotopes in Understanding Hydrological and Hydrochemical Processes)

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20 pages, 3156 KB

Open AccessArticle

Environmental Impact of a Portable Nature-Based Solution (NBS) Coupled with Solar Photocatalytic Oxidation for Decentralized Wastewater Treatment

by Lobna Mansouri, Sabrine Saadellaoui, Riccardo Bresciani, Khaoula Masmoudi, Hanen Jarray, Thuraya Mellah, Ahmed Ghrabi, Hanene Akrout, Latifa Bousselmi and Fabio Masi

Water 2026, 18(3), 422; https://doi.org/10.3390/w18030422 - 5 Feb 2026

Viewed by 906

Abstract

This study presents a life cycle assessment of a low-cost pilot-scale wastewater treatment system that combines solar photocatalytic oxidation with Nature-based Solutions (NBSs) for a specially constructed wetland (CW). The prototype was designed and assessed for its efficiency in treating urban wastewater and [...] Read more.

This study presents a life cycle assessment of a low-cost pilot-scale wastewater treatment system that combines solar photocatalytic oxidation with Nature-based Solutions (NBSs) for a specially constructed wetland (CW). The prototype was designed and assessed for its efficiency in treating urban wastewater and its environmental impact on agricultural irrigation reuse. Evaluations were performed with the SimaPro software, applying the Impact ReCiPe Medpoint methodology, which includes characterization and selection of the relevant environmental issues steps. The results demonstrate the potential of this hybrid system for providing high-quality treated wastewater suitable for agricultural reuse in water-scarce regions. The analysis reveals that the operational phase, mainly driven by energy consumption for pumping, aeration, and photocatalytic processes, accounts for over 85–98% of the total global warming potential (GWP), primarily due to reliance on fossil-based electricity. Conversely, the construction phase significantly impacts land use and toxicity categories, with concrete and substrate production contributing around 95% to land occupation and 97% to human toxicity. The photocatalytic subsystem also contributes notably to embodied carbon at 42.4%, owing to energy-intensive manufacturing. The results underscore the importance of optimizing operational energy efficiency and selecting sustainable materials to mitigate environmental burdens. The integrated system demonstrates promising potential for producing high-quality treated effluent suitable for agricultural reuse in water-scarce regions, supporting sustainable water management. These findings provide important insights for reducing ecological impacts and advancing environmentally sustainable wastewater treatment solutions. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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21 pages, 4011 KB

Open AccessArticle

Projected Future Trends in Runoff and Sediment Transport in Typical Rivers of the Yellow River Basin, China

by Beilei Liu, Yongbin Wei, Chuanming Wang, Xiaorong Chen, Pan Wang, Jianye Ma and Peng Li

Water 2026, 18(3), 421; https://doi.org/10.3390/w18030421 - 5 Feb 2026

Viewed by 553

Abstract

This study systematically evaluated the response mechanisms of water and sediment processes in the Kuye River Basin to climate change and human activities from 2023 to 2053 by integrating multi-source climate scenarios (CMIP5 models), land-use change projections (based on the Markov chain model), [...] Read more.

This study systematically evaluated the response mechanisms of water and sediment processes in the Kuye River Basin to climate change and human activities from 2023 to 2053 by integrating multi-source climate scenarios (CMIP5 models), land-use change projections (based on the Markov chain model), and a distributed hydrological model (SWAT model). The results indicate that under the RCP8.5 high-emission scenario, annual precipitation in the basin shows a non-significant increasing trend but with intensified interannual variability. Spatially, precipitation exhibits a pattern of increasing from northwest to southeast, with a marked decadal transition occurring around 2043. Land-use structure undergoes significant transformation, with construction land projected to account for 30.54% of the total basin area by 2050, while grassland and cropland continue to decline. Water and sediment processes display distinct phased characteristics: a fluctuating adjustment phase (2023–2033), a relatively stable phase (2034–2043), and a sharp growth phase (2044–2053). Parameter sensitivity analysis identifies the curve number (CN2) and soil bulk density (SOL_BD) as key regulatory parameters, revealing the synergistic mechanism by which land-use changes amplify climatic effects through alterations in surface properties. Based on the findings, an adaptive watershed management framework is proposed, encompassing dynamic water resource regulation, spatial zoning, targeted erosion control, and iterative scientific management. Particular emphasis is placed on addressing hydrological transition risks around 2043 and promoting low-impact development practices in high-erosion areas. This study provides a scientific basis for the integrated management of water and soil resources in the context of ecological conservation and high-quality development in the Yellow River Basin. The methodology developed herein offers a valuable reference for predicting water and sediment processes and implementing adaptive management in similar semi-arid basins. Full article

(This article belongs to the Special Issue Soil Erosion and Soil and Water Conservation, 2nd Edition)

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27 pages, 6053 KB

Open AccessArticle

Riverbed Evolution Trends Based on the Channel-Forming Discharge Concept: A Climate Change Scenario Analysis to 2100 for the Ialomița River, Romania

by Andrei Radu, Laura Comănescu, Nicu Ciobotaru and Romulus Costache

Water 2026, 18(3), 420; https://doi.org/10.3390/w18030420 - 5 Feb 2026

Viewed by 1202

Abstract

Nowadays, river systems exhibit significant geomorphic changes that primarily reflect their response to the climate signal, driven by ongoing climate change. In this context, detecting future trends in riverbed dynamics is crucial, especially from a river management perspective. The purpose of the study [...] Read more.

Nowadays, river systems exhibit significant geomorphic changes that primarily reflect their response to the climate signal, driven by ongoing climate change. In this context, detecting future trends in riverbed dynamics is crucial, especially from a river management perspective. The purpose of the study is to identify long-term trends in riverbed evolution at the Băleni gauging station on the Ialomița River, based on the channel-forming discharge concept, through the end of the 21st century. To achieve this, a comprehensive methodology was developed that primarily focuses on calculating the effective discharge (Qe) as a key driver of riverbed dynamics, using discharges simulated by the E–HYPE hydrological model forced by eight EURO–CORDEX EUR–11 ensemble climate projections under the RCP 4.5 and RCP 8.5 scenarios up to 2100. The results of the study indicate Qe values ranging between 7.49 m³/s and 12.79 m³/s for RCP 4.5, and between 5.66 m³/s and 13.94 m³/s for RCP 8.5. Based on the ensemble mean of Qe, different riverbed evolution trends and are identified: a state of dynamic equilibrium under RCP 4.5, suggesting that the riverbed is probable to maintain its geomorphological state similar to the present; and pronounced variability under RCP 8.5, indicating intense erosion processes until mid-century, followed by a slight aggradation trend that may intensify at the end of the century, with Qe being 23.27% lower than the reference period. Overall, the Qe_8.5 evolution suggests a potential future alteration of the Ialomița riverbed. Beyond its main findings, this study provides a methodological framework for assessing future effective discharge and may support river management and restoration planning in the study area. Full article

(This article belongs to the Section Water Erosion and Sediment Transport)

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25 pages, 7021 KB

Open AccessArticle

Decadal Runoff Variability Under Moderate and Extreme Climate Scenarios: A SWAT Modeling Study for a Postglacial Lowland Catchment (NW Poland)

by Mikołaj Majewski, Witold Bochenek and Joanna Gudowicz

Water 2026, 18(3), 419; https://doi.org/10.3390/w18030419 - 5 Feb 2026

Viewed by 552

Abstract

The study investigates the projected impact of climate change on water runoff in the upper Parsęta catchment, a postglacial lowland basin located in northwestern Poland. In the first step of the analysis, hydrological simulations for the period 2005–2022 were conducted using the Soil [...] Read more.

The study investigates the projected impact of climate change on water runoff in the upper Parsęta catchment, a postglacial lowland basin located in northwestern Poland. In the first step of the analysis, hydrological simulations for the period 2005–2022 were conducted using the Soil and Water Assessment Tool (SWAT). Model calibration and validation, performed in SWAT-CUP with the SUFI2 algorithm, yielded satisfactory performance (R² = 0.66–0.80; PBIAS = 0.43–13.87). Based on the calibrated model, projected simulations were performed for three future decades (2021–2030, 2031–2040, and 2041–2050) under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Climate input data were derived from the KLIMADA 2.0 national database, which was developed using down-scaled regional climate model output from the EURO-CORDEX ensemble and statistical bias-correction methods to generate high-resolution projections. Under RCP4.5, mean annual runoff increased by approximately 13–26%, while under RCP8.5, the changes were more variable, ranging from 2% to 28% relative to the 2011–2020 baseline. Seasonal analyses revealed enhanced autumn–winter runoff and lower spring–summer flows. The findings highlight that moderate climate forcing can lead to substantial alterations in hydrological regimes in postglacial lowland catchments, in certain decades comparable in magnitude to those projected under extreme forcing, underscoring the need for adaptive water management in northern Poland. Full article

(This article belongs to the Section Water and Climate Change)

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19 pages, 7804 KB

Open AccessArticle

Wetland Landscape Response to Partially Treated Sewage in Unconstrained Systems

by R. Eugene Turner, James E. Bodker and Christopher Schulz

Water 2026, 18(3), 418; https://doi.org/10.3390/w18030418 - 5 Feb 2026

Viewed by 560

Abstract

We conducted a long-term assessment of how natural free-water surface (FWS) wetlands respond to sustained loads of partially treated municipal effluent. We quantified the effects on vegetative cover, ammonium concentration, and fecal coliform bacteria densities and compared them to constructed wetlands with hydrologically [...] Read more.

We conducted a long-term assessment of how natural free-water surface (FWS) wetlands respond to sustained loads of partially treated municipal effluent. We quantified the effects on vegetative cover, ammonium concentration, and fecal coliform bacteria densities and compared them to constructed wetlands with hydrologically defined flows. Variations in the area of open water and floating vegetation converted from emergent marsh, shrub or bottomland hardwood forest (0 to 124.6 ha) were directly proportional to the nitrogen loading at all eight sites (range 5.4 to 24.6 thousand Kg N yr⁻¹). Trees exposed to effluent at five locations sometimes died in the first year, or they took decades to die. At the one location with fecal coliform data, their densities were directly related to ammonium concentrations, which were within the concentration range of untreated municipal sewage water. Ammonium levels exceeded US EPA chronic toxicity standards at three locations and aquatic toxicity levels developed by independent scientists at all eight locations. The loss of organic peat and habitat has multiple consequential effects that may be quick to happen or subtle, and be slow to restore, if at all. Compared to constructed wetland treatment systems, FWS systems are more difficult to constrain, have much reduced predictabilities and bring unwelcome consequences. Full article

(This article belongs to the Special Issue Water Quality, Wastewater Treatment and Water Recycling, 2nd Edition)

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23 pages, 14508 KB

Open AccessArticle

Evaluating the Applicability of the wflow_sbm Model with Seamless Parameter Maps for Flood Simulation in Small- and Medium-Sized Catchments

by Shuaihong Zang, Xiuguang Wu, Jinbin Mu and Mingkun Sun

Water 2026, 18(3), 417; https://doi.org/10.3390/w18030417 - 5 Feb 2026

Viewed by 522

Abstract

Flood simulation in small- and medium-sized catchments is hindered by data scarcity and strong hydroclimatic heterogeneity. Distributed models with pedotransfer functions offer new opportunities, yet their parameter sensitivity and regional applicability remain insufficiently understood. In this study, the wflow_sbm model was applied to [...] Read more.

Flood simulation in small- and medium-sized catchments is hindered by data scarcity and strong hydroclimatic heterogeneity. Distributed models with pedotransfer functions offer new opportunities, yet their parameter sensitivity and regional applicability remain insufficiently understood. In this study, the wflow_sbm model was applied to two catchments: the humid Tunxi basin and the semi-humid Chenhe basin, China. Model seamless parameters, defined as spatially continuous fields derived directly from global datasets using pedotransfer functions without local calibration, were generated using the HydroMT system. The parameter sensitivity, applicability of pedotransfer function derived parameters, and model performance were systematically evaluated and benchmarked against the well-established Xin’anjiang (XAJ) model, which is a conceptual lumped hydrological model widely used for flood simulation in humid and semi-humid regions of China. Sensitivity analysis identified KsatHorFrac and InfiltCapSoil as dominant in Tunxi, and KsatHorFrac and SoilThickness in Chenhe. SoilThickness derived by HydroMT underestimated flood volumes in the Chenhe basin but was substantially improved after applying a uniform scaling factor of 0.1, resulting in an effective SoilThickness of approximately 0.2 m. The wflow_sbm model achieved performance comparable to the XAJ model. Optimal calibration achieved N_SE = 0.85 in Tunxi with good performance at internal sub-catchments (Yuetan and Chengcun, N_SE > 0.70), and generally above 0.7 in Chenhe. These findings highlight the region-dependent validity of parameterization and provide guidance for distributed flood modeling in data-scarce basins. Full article

(This article belongs to the Special Issue Application of Various Hydrological Modeling Techniques and Methods in River Basin Management, 2nd Edition)

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15 pages, 3301 KB

Open AccessArticle

Environmental Evolution Recorded by Tamarix Nebkhas in the Qaidam Basin

by Yongxin Zeng, Chongyi E, Jiawei Wang, Qiuming Tong, Kejia Li and Ming Tang

Water 2026, 18(3), 416; https://doi.org/10.3390/w18030416 - 5 Feb 2026

Viewed by 596

Abstract

A typical Tamarix nebkha was studied in the southern Qaidam Basin, China. K-feldspar pIRIR dating was applied to establish a reliable chronological framework, and an Undatable age–depth model was constructed. Accumulation rates (AR) declined in stages: rapid (~1.33 cm/a; ~370–260 yr BP), slower [...] Read more.

A typical Tamarix nebkha was studied in the southern Qaidam Basin, China. K-feldspar pIRIR dating was applied to establish a reliable chronological framework, and an Undatable age–depth model was constructed. Accumulation rates (AR) declined in stages: rapid (~1.33 cm/a; ~370–260 yr BP), slower (~0.75 cm/a; ~260–130 yr BP), and slowest (~0.31 cm/a; ~130 yr BP-present). This dynamic pattern is likely influenced by a combination of regional aeolian activity variations, geomorphological evolution, and the intrinsic growth dynamics of the nebkha itself. To further understand the relationship between nebkha development and climatic conditions, a δ¹³C sequence was reconstructed using Tamarix plant remains preserved within the sediments. Based on shifts in leaf-level δ¹³C values, which indicate changes in water use efficiency, water availability over the past 370 years was inferred and divided into three main phases: relatively sufficient from 1650 to 1690, gradually decreasing during 1690–1870, and increasing again after 1870. The δ¹³C trend closely correlates with temperature variations derived from δ¹⁸O records of the Malan ice core. This suggests that in this hyper-arid region, the development of Tamarix nebkhas is primarily controlled by glacial meltwater and snowmelt runoff from the Kunlun Mountains, rather than by local precipitation. Full article

(This article belongs to the Topic Past, Current and Future Processes in the Earth Critical Zone)

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13 pages, 935 KB

Open AccessReview

Diel Variability of CO₂ and CH₄ from Inland Waters: Patterns, Drivers, and Implications

by Lingling Li, Jiale Zhu, Yunqiao Shao, Yuwen Qian and Renhua Yan

Water 2026, 18(3), 415; https://doi.org/10.3390/w18030415 - 5 Feb 2026

Viewed by 732

Abstract

Inland waters exhibit pronounced temporal variability in CO₂ and CH₄ emissions. However, existing research has predominantly focused on seasonal to interannual scales, with most field measurements conducted during daytime hours. Consequently, diel (24 h) emission dynamics remain poorly characterized. This study [...] Read more.

Inland waters exhibit pronounced temporal variability in CO₂ and CH₄ emissions. However, existing research has predominantly focused on seasonal to interannual scales, with most field measurements conducted during daytime hours. Consequently, diel (24 h) emission dynamics remain poorly characterized. This study synthesizes current knowledge on diel variations in CO₂ and CH₄ fluxes across inland water bodies—including rivers, lakes, reservoirs, and ponds—with particular attention to day–night contrasts. Based on the limited available data, the average day-to-night flux ratios are 0.87 for CO₂ and 1.44 for CH₄. Exclusive reliance on daytime sampling may therefore underestimate daily CO₂ emissions by approximately 13% while overestimating CH₄ emissions by a similar magnitude. Diel fluctuations in water temperature and wind speed—driving corresponding changes in surface water gas concentrations and air–water gas transfer velocity—represent primary controls on these emission patterns. Secondary influences include solar radiation, dissolved oxygen, pH, and nutrient availability. Future efforts should prioritize high-frequency monitoring of diel carbon emission cycles and mechanistic analysis of their drivers, ultimately enabling the development of large-scale models that explicitly incorporate diel dynamics. Such advances are essential for accurate quantification and correction of carbon emissions from inland waters at regional to global scales. Full article

(This article belongs to the Topic Climate Change and Human Impact on Freshwater Water Resources: Rivers and Lakes, 2nd Edition)

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5 pages, 150 KB

Open AccessEditorial

Mathematical, Physical, Chemical and Biological Methods for Ice and Water Problems

by Zhijun Li and Fang Li

Water 2026, 18(3), 414; https://doi.org/10.3390/w18030414 - 5 Feb 2026

Viewed by 460

Abstract

High-latitude and cold-region environments feature tightly coupled hydrological, cryospheric, and ecological subsystems, where seasonal freeze–thaw cycles, snow cover, permafrost, and river and lake ice fundamentally shape water flows and ecosystem processes [...] Full article

(This article belongs to the Special Issue Mathematical, Physical, Chemical, and Biological Methods for Ice and Water Problems)

21 pages, 4007 KB

Open AccessArticle

Contrasting Water Quality Responses During Drought Development Versus Recovery in Poyang Lake

by Shan He, Jijun Xu and Kuibing Zhao

Water 2026, 18(3), 413; https://doi.org/10.3390/w18030413 - 4 Feb 2026

Viewed by 586

Abstract

Drought leads to declining water levels and reduced water volume in lakes, significantly altering their water quality. Current research has primarily examined water quality during drought episodes or compared conditions before and after such events. However, the variations in water quality indicators and [...] Read more.

Drought leads to declining water levels and reduced water volume in lakes, significantly altering their water quality. Current research has primarily examined water quality during drought episodes or compared conditions before and after such events. However, the variations in water quality indicators and their relationships with hydrological factors across different drought stages, particularly during development and recovery periods, remain poorly understood. To address this gap, we investigated the stage-specific impacts of hydrological drought on lake water quality. Hydrological drought events were identified and segmented into development and recovery stages using the Standardized Water Level Index. Eight water quality indicators, including total nitrogen (TN) and total phosphorus (TP), were analyzed together with hydrological variables using Grey Relational Analysis (GRA). Poyang Lake, the largest freshwater lake in China, served as the case study. The results revealed significant spatio-temporal heterogeneity in both drought characteristics and water quality responses. Development periods were generally longer than recovery periods. Dissolved oxygen (DO) was consistently lower during drought development, whereas TP increased during recovery. GRA indicated that the main drivers of TN and TP shifted across drought stages. During the development period, TN and TP were more closely coupled, and permanganate index and turbidity exerted strong influences. In contrast, during the recovery period, TN was primarily associated with conductivity, while TP became mainly dominated by turbidity. This paper not only supplements the theoretical understanding of the interaction between hydrological drought and water quality, but also provides scientific support for water quality early warning, and the water resource management of large freshwater lakes under drought scenarios. Full article

(This article belongs to the Special Issue Climate Change Adaptation in Water Resource Management)

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32 pages, 1418 KB

Open AccessReview

Advances in Phytoremediation-Based Strategies for Co-Contaminated Riparian Soils: A Review

by Jian Wang, Na Luo and Bin Ji

Water 2026, 18(3), 412; https://doi.org/10.3390/w18030412 - 4 Feb 2026

Cited by 1 | Viewed by 1688

Abstract

Riparian soils co-contaminated with heavy metals and organic pollutants present a formidable environmental challenge; conventional single-target remediation strategies are frequently insufficient due to the synergistic interactions between contaminant classes. This review offers a systematic synthesis of phytoremediation as an integrative and ecologically sustainable [...] Read more.

Riparian soils co-contaminated with heavy metals and organic pollutants present a formidable environmental challenge; conventional single-target remediation strategies are frequently insufficient due to the synergistic interactions between contaminant classes. This review offers a systematic synthesis of phytoremediation as an integrative and ecologically sustainable paradigm for addressing these complex multi-pollutant scenarios. Through a critical examination of underlying mechanisms—namely phytoextraction, rhizodegradation, phytostabilization, and phytovolatilization—we evaluate the efficacy of selected hyperaccumulator and pollution-tolerant species in simultaneously mitigating inorganic (e.g., Pb, Cd, As) and organic (e.g., PAHs, pesticides) contaminants. Furthermore, the discussion highlights emerging strategic integrations, including genetic engineering for enhanced metal accumulation, the application of engineered nanomaterials to modulate pollutant bioavailability and plant stress tolerance, rhizosphere amendment with low-molecular-weight organic acids, and biochar-mediated immobilization coupled with microbial stimulation. The analysis posits that phytoremediation, particularly when augmented by these advanced synergies, constitutes a viable, multifunctional, and environmentally benign strategy for the holistic restoration of riparian ecosystems. Future inquiries should prioritize the mechanistic elucidation of combined technologies, the development of predictive performance models, and rigorous long-term field validation to guarantee operational efficacy and environmental safety. Full article

(This article belongs to the Section Water and One Health)

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16 pages, 1142 KB

Open AccessArticle

Impacts of Extreme Temperature and Drought on Water Quality and Phytoplankton Biomass in Nanwan Reservoir (China)

by Kunjie Wu, Zhiguo Hu, Yuan Tian, Xin Liu, Chenxi Ju, Chaoqun Su, Yuanye Ma, Huanan Gao, Liangjie Zhao and Xusheng Guo

Water 2026, 18(3), 411; https://doi.org/10.3390/w18030411 - 4 Feb 2026

Viewed by 937

Abstract

Climate change has led to increasingly frequent and unpredictable droughts and high-temperature events, creating extreme conditions that profoundly impact the productivity of freshwater ecosystems. In this study, we evaluated the effects of extreme temperature and drought events on Nanwan Reservoir, a large, deep [...] Read more.

Climate change has led to increasingly frequent and unpredictable droughts and high-temperature events, creating extreme conditions that profoundly impact the productivity of freshwater ecosystems. In this study, we evaluated the effects of extreme temperature and drought events on Nanwan Reservoir, a large, deep body of water in Xinyang, China, by assessing water quality and phytoplankton biomass. Field investigations were conducted during both high-temperature and drought (HTD) conditions in 2019 and normal-temperature and non-drought (NTND) conditions in 2020. HTD conditions significantly disrupted the thermocline and oxycline structures, leading to prolonged stratification during this period. Although phosphorus concentrations remained relatively stable across both periods, nitrogen levels were markedly lower during HTD events, indicating a possible shift in nutrient limitation from phosphorus to nitrogen. Additionally, a complex relationship between environmental variables and phytoplankton biomass was observed under HTD conditions. These findings advance our understanding of primary production responses to extreme weather events in Nanwan Reservoir, highlighting the importance of incorporating this knowledge into water resource management and ecological conservation strategies. Full article

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

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16 pages, 2368 KB

Open AccessArticle

Mechanical Properties, Acoustic Emission (AE), and Electromagnetic Radiation (EMR) Characteristics of Sandstone with Different Water Contents Under Impact Loading

by Yonghong Liu, Fujun Zhao, Qiuhong Wu and Zhouyuan Ye

Water 2026, 18(3), 410; https://doi.org/10.3390/w18030410 - 4 Feb 2026

Viewed by 542

Abstract

To analyze the characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals in specimens with different water contents during impact loading, impact tests were conducted on sandstone under dry, natural, and saturated conditions using the split Hopkinson pressure bar (SHPB) system. The [...] Read more.

To analyze the characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals in specimens with different water contents during impact loading, impact tests were conducted on sandstone under dry, natural, and saturated conditions using the split Hopkinson pressure bar (SHPB) system. The results show that water reduces the dynamic compressive strength and elastic modulus of sandstone, changes the failure mode from tensile failure to tensile-shear failure, and increases the amount of small-sized fragments after failure. AE and EMR signals effectively reflect the entire deformation process of specimens with different water contents under impact loading. In the elastic stage, only EMR signals appear, indicating that EMR is more sensitive to crack generation. In the yield stage, the AE signal count and energy increase sharply, indicating that the response to specimen failure is better. By comparing AE and EMR signals at different stages, it was found that water inhibits both the propagation and energy of AE and EMR signals. The damage factor D, quantified by AE and EMR counts, accurately represents the damage suffered by specimens with different water contents during impact loading. This study significantly advances the understanding of failure mechanisms in specimens with varying water contents and contributes to practical engineering monitoring of water-bearing rock mass stability. Full article

(This article belongs to the Special Issue Water-Triggered Geo-Hazards in Underground and Geotechnical Engineering: Mechanisms, Early Warning and Sustainable Mitigation)

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21 pages, 3387 KB

Open AccessArticle

Ecotoxicity of Antivirals Used to Treat COVID-19 Patients: Analysis of Related Structural Features

by Matija Cvetnić, Viktorija Martinjak, Martina Miloloža Nikolić, Luka Večenaj, Dora Lastovčić, Lidija Furač, Dajana Kučić Grgić, Tomislav Bolanča and Šime Ukić

Water 2026, 18(3), 409; https://doi.org/10.3390/w18030409 - 4 Feb 2026

Viewed by 566

Abstract

Antiviral substances are considered emerging contaminants. Once released into the environment, they may affect organisms through complex and often still-unknown mechanisms. This study focuses on a class of antiviral substances with potential use in treating COVID-19 patients, aiming to identify specific structural characteristics [...] Read more.

Antiviral substances are considered emerging contaminants. Once released into the environment, they may affect organisms through complex and often still-unknown mechanisms. This study focuses on a class of antiviral substances with potential use in treating COVID-19 patients, aiming to identify specific structural characteristics that significantly contribute to their ecotoxicity. An empirical approach called quantitative structure–activity relationship (QSAR) was used for this purpose. The study examined 13 antiviral substances: atazanavir, daclatasvir, darunavir, emtricitabine, favipiravir, lopinavir, nirmatrelvir, oseltamivir, remdesivir, ribavirin, ritonavir, and sofosbuvir. The ecotoxicity of these antivirals was assessed using three tests: the Aliivibrio fischeri test, the Chlorella sp. test, and the Pseudomonas putida test. These three microorganisms represent different trophic levels in aquatic and soil ecosystems. Ecotoxicity was expressed as EC₂₀ and EC₅₀, and these values served as the dependent variables in the QSAR models. A large set of numerical descriptors calculated from the molecular structures of the antivirals was used as an independent variable. EC₂₀-based QSAR models offer insight into the effects of antivirals under sub-lethal exposure conditions. The results indicated that sub-lethal exposure in Aliivibrio fischeri was associated with favorable electronic properties and compact structures that promote cellular accumulation, while long-range fragments reduced toxicity. In Chlorella sp., sub-lethal exposure was driven by optimal molecular size, chain length, and specific electronic groups enabling cell penetration and biochemical inhibition. For sub-lethal exposure in P. putida, lipophilicity and reactive group geometry enhanced toxicity, while high short-range polarity mitigated it by limiting membrane permeability. Acute toxicity patterns showed similar trade-offs: strong electronic reactivity increased potency, but steric bulk, long-range polarity, or unfavorable mass distribution frequently restricted bioavailability and reduced toxic effects. Overall, the models demonstrated that antiviral toxicity results from a balance of electronic activity, structural accessibility, and physicochemical constraints, providing a mechanistic basis for predicting the environmental risk of selected antiviral substances. Full article

(This article belongs to the Section Water and One Health)

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25 pages, 4996 KB

Open AccessArticle

Spatiotemporal Analysis of the Groundwater Level in Meoqui, Chihuahua, Mexico—Water for the Future in a Growing Area in the North Central Desert of Mexico

by Martín Alfredo Legarreta-González, Cesar A. Meza-Herrera, Rafael Rodríguez-Martínez, Darithsa Loya-González, Carlos Servando Chávez-Tiznado, Pedro Antonio Robles-Trillo, Fernando Arellano-Rodríguez, Angeles De Santiago-Miramontes and Francisco Gerardo Véliz-Deras

Water 2026, 18(3), 408; https://doi.org/10.3390/w18030408 - 4 Feb 2026

Viewed by 1523

Abstract

A variety of statistical techniques were assessed for their usefulness for analysing the pattern of geographical and temporal changes in groundwater levels in order to diagnose the water supply in Meoqui, Chihuahua, which is situated in dry North-Central Mexico. These included Facebook Prophet, [...] Read more.

A variety of statistical techniques were assessed for their usefulness for analysing the pattern of geographical and temporal changes in groundwater levels in order to diagnose the water supply in Meoqui, Chihuahua, which is situated in dry North-Central Mexico. These included Facebook Prophet, Lasso, generalized linear regularized models (GLMNET), autoregressive-integrated moving average (ARIMA), and a hybrid approach that merged Prophet and XGBoost. This was conducted on the assumption that the levels varied during the year and that it was possible to perform statistical analyses that derived a model explaining the changes and allowing for spatiotemporal prediction. The data set encompassed the period between 2020 and 2025 and was obtained from the Junta Municipal de Aguas y Saneamiento (JMAS) in Meoqui. The data set consisted of eight wells from which water was extracted for human consumption. The ARIMA model was identified as the optimal method for generating predictions on a monthly and annual basis. Furthermore, an inverse distance weighted (IDW) interpolation approach was utilised to conduct a spatial analysis. This enabled the visualisation of the predicted spatiotemporal changes in groundwater levels. The mean overall level was determined to be 26 m ± 16, with a minimum of 3 m and a lower level of 64 m. Models were estimated, comprising a general model and models specific to each well type. The best model for general level was Facebook Prophet (MAE 6.31, MAPE 16.28, MASE 1.23, SMAPE 16.79, RMSE 7.25, R-sq 0.29). The Sen’s slope of the historic level was found to be 0.38 (p < 0.001), thus indicating a decline in the groundwater level. The spatiotemporal analysis indicated a monthly decline in water levels from February to August, followed by an improvement in levels until November, which were then maintained until January. The lowest levels were observed in the area associated with Well 5. The findings of this study offer valuable insights into the spatiotemporal patterns of groundwater in the region, which could inform the development of sustainable groundwater management policies. Full article

(This article belongs to the Section Hydrogeology)

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