Water

22 pages, 21059 KB

Open AccessArticle

Numerical Investigation of the Erosive Dynamics of Glacial Lake Outburst Floods: A Case Study of the 2020 Jinwuco Event in Southeastern Tibetan Plateau

by Shuwu Li, Changhu Li, Pu Li, Yifan Shu, Zhengzheng Li and Zhang Wang

Water 2025, 17(19), 2837; https://doi.org/10.3390/w17192837 (registering DOI) - 27 Sep 2025

Abstract

Glacial lake outburst floods (GLOFs) represent increasingly common and high-magnitude geohazards across the cryosphere of the Tibetan Plateau, particularly under ongoing climate warming and glacier retreat. This study combines multi-temporal remote sensing imagery and detailed Flo-2D hydrodynamic modeling to investigate the erosive dynamics [...] Read more.

Glacial lake outburst floods (GLOFs) represent increasingly common and high-magnitude geohazards across the cryosphere of the Tibetan Plateau, particularly under ongoing climate warming and glacier retreat. This study combines multi-temporal remote sensing imagery and detailed Flo-2D hydrodynamic modeling to investigate the erosive dynamics of the 2020 Jinwuco GLOF in Southeastern Tibetan Plateau. Key conclusions include: (1) The 2.35 km-long flood routing channel exhibits pronounced non-uniformity in horizontal curvature, channel width, and cross-sectional shape, significantly influencing flood propagation; five representative cross-sections divide the channel into six distinct segments. (2) Prominent lateral erosion occurred proximally to the dam, attributable to extreme erosive forces and high sediment transport capacity during peak discharge, with horizontal channel curvature further amplifying local impact and erosion. (3) Erosion rates were highest near the dam and in downstream narrow segments, while mid-reach sections with greater width experienced lower erosion. (4) Maximum flow depths reached 28.12 m in topographically confined reaches, whereas peak velocities occurred in upstream and downstream curved sections. (5) The apparent critical erosive shear stress of bank material is controlled not only by soil strength but also by flood dynamics and pre-existing channel morphology, indicating strong feedback between flow dynamics, channel morphology, and critical erosive shear stress of bank material. This study provides a generalized and transferable framework for analyzing GLOF-related erosion in data-scarce high-altitude regions, offering critical insights for hazard assessment, regional planning, and risk mitigation strategies. Full article

(This article belongs to the Special Issue Water-Related Landslide Hazard Process and Its Triggering Events)

► Show Figures

Figure 1

14 pages, 3670 KB

Open AccessArticle

Study on Natural Background Levels and Mechanisms of Groundwater Contamination in an Overexploited Aquifer Region: A Case Study of Xingtai City, North China Plain

by Qi Wang, Meili Wang, Yan Li, Binghao Guo, Hongchao Li, Yang Liu, Liya Zhao, Chunyang Ma and Ziting Yuan

Water 2025, 17(19), 2836; https://doi.org/10.3390/w17192836 (registering DOI) - 27 Sep 2025

Abstract

This study investigates the groundwater over-exploitation zone in Xingtai City, North China Plain, to address two critical gaps in the current understanding of groundwater chemistry: the lack of established natural background levels (NBLs) and the ambiguous mechanisms of groundwater contamination. Sixty shallow-groundwater samples [...] Read more.

This study investigates the groundwater over-exploitation zone in Xingtai City, North China Plain, to address two critical gaps in the current understanding of groundwater chemistry: the lack of established natural background levels (NBLs) and the ambiguous mechanisms of groundwater contamination. Sixty shallow-groundwater samples were collected and analyzed using a combination of Piper diagrams, cumulative-probability statistics, contamination-index methods, and multivariate statistical techniques to determine NBLs and threshold values (TVs) for major chemical constituents and to clarify the contamination mechanisms. The results indicate that the groundwater is weakly alkaline, with the most prevalent water types being HCO₃–Na and SO₄·Cl–Na. The NBLs for Na⁺, Ca²⁺, Mg²⁺, Cl⁻,

S O_{4}^{2 -}

and

N O_{3}^{-}

are 32.3 mg/L, 34.1 mg/L, 17.8 mg/L, 46.2 mg/L, 66.4 mg/L and 0.886 mg/L, respectively, and the corresponding TVs are 116 mg/L, 54.6 mg/L, 33.9 mg/L, 248 mg/L, 258 mg/L and 44.7 mg/L. Based on the TVs, 56.7% of the sampling sites are identified as anthropogenically contaminated. Principal component analysis reveals that groundwater over-extraction, industrial activities and water–rock interaction are the dominant drivers of groundwater contamination, whereas intensive abstraction, agricultural fertilization and domestic sewage discharge exert additional influence. The findings provide a scientific basis for pollution control and sustainable utilization of groundwater in over-exploited regions. Full article

(This article belongs to the Special Issue Pollution Mechanisms and Source Apportionment of Typical Pollutants in Aquatic Environments)

► Show Figures

Figure 1

30 pages, 1964 KB

Open AccessArticle

Water Demand and Conservation in Arid Urban Environments: Numerical Analysis of Evapotranspiration in Arizona

by Jaden Lu and Zbigniew J. Kabala

Water 2025, 17(19), 2835; https://doi.org/10.3390/w17192835 (registering DOI) - 27 Sep 2025

Abstract

Water management in arid regions, such as Arizona, is critical due to increasing demands from the urban, agricultural, and recreational sectors. In this study, Finite element analysis software COMSOL Multiphysics (COMSOL 6.3) is used to quantify water demands in Chandler, Arizona. Evapotranspiration from [...] Read more.

Water management in arid regions, such as Arizona, is critical due to increasing demands from the urban, agricultural, and recreational sectors. In this study, Finite element analysis software COMSOL Multiphysics (COMSOL 6.3) is used to quantify water demands in Chandler, Arizona. Evapotranspiration from vegetation and pools is studied. Factors are divided into environmental (temperature, humidity, wind speed) and soil-related properties (moisture content, hydraulic conductivity), which are modeled and used to estimate annual water losses. This study represents the first comprehensive investigation of the usage across several main categories at Arizona. Results indicate that pools contribute 61% of surface water evaporation. Annual water demand in Chandler for 2024 peaks at 425,000 m³ in June, with irrigation for vegetation dominating consumption. Validation against experimental data confirms model accuracy. This simulation work aims to provide scalable insights for water management in arid urban environments. Based on the simulation, various solutions were proposed to reduce water consumption and minimize water loss. Some active measures include the optimization of irrigation time and frequency based on dynamic and real-time environmental conditions. The proposed solution can help minimize the water consumption while maintaining the water demands for plant life sustenance. Other passive measures include the modification of localized environmental conditions to reduce water evaporation. In particular, it was found that fence installation can significantly change the water vapor flow and distribution close to the water surface and suppress the water evaporation by simply lowering the wind speed right above the water surface. A logical takeaway is that evaporation would also decrease when pools are built with deeper water surfaces. Full article

(This article belongs to the Special Issue Groundwater Flow and Transport Modeling in Aquifer Systems: 2nd Edition)

21 pages, 7401 KB

Open AccessArticle

Integrated Ecological Security Assessment: Coupling Risk, Health, and Ecosystem Services in Headwater Regions—A Case Study of the Yangtze and Yellow River Source

by Zhiyi Li, Jijun Xu, Zhe Yuan and Li Wang

Water 2025, 17(19), 2834; https://doi.org/10.3390/w17192834 (registering DOI) - 27 Sep 2025

Abstract

The Source Region of the Yangtze and Yellow Rivers (SRYY), situated on the Qinghai-Tibet Plateau, serves as a vital ecological barrier and a critical component of the global carbon cycle. However, this region faces severe ecosystem degradation driven by climate change and human [...] Read more.

The Source Region of the Yangtze and Yellow Rivers (SRYY), situated on the Qinghai-Tibet Plateau, serves as a vital ecological barrier and a critical component of the global carbon cycle. However, this region faces severe ecosystem degradation driven by climate change and human activities. This study establishes an integrated ecological security assessment framework that couples ecological risk, ecosystem health, and ecosystem services to evaluate ecological dynamics in the SRYY from 2000 to 2020. Leveraging multi-source data (vegetation, hydrological, meteorological) and advanced modeling techniques (spatial statistics, geographically weighted regression), we demonstrate that: (1) The Ecological Security Index (ESI) exhibited an initial increase followed by a significant decline after 2010, falling below its 2000 level by 2020. (2) The rising Ecological Risk Index (ERI) directly weakened both the ESI and Ecosystem Service Index (ESsI), with this negative effect intensifying markedly post-2010. (3) A distinct spatial gradient pattern emerged, shifting from high-security core areas in the east to low-security zones in the west, closely aligned with terrain and elevation; conversely, areas exhibiting abrupt ESI changes showed little correlation with permafrost degradation zones. (4) Vegetation coverage emerged as the key driver of ESI spatial heterogeneity, acting as the central hub in the synergistic regulation of ecological security by climate and topographic factors. Full article

(This article belongs to the Special Issue Wetland Conservation and Ecological Restoration, 2nd Edition)

► Show Figures

Figure 1

25 pages, 3431 KB

Open AccessReview

Heavy Metal Transport in Dammed Rivers: Damming Effects and Remediation Strategies—A Review

by Rong Huang, Sitong Liu, Qiusheng Yuan, Xun Wang, Lingxiao Ren, Linqian Rong and Yuting Pan

Water 2025, 17(19), 2833; https://doi.org/10.3390/w17192833 (registering DOI) - 27 Sep 2025

Abstract

Rivers, vital for life and civilizations, face severe threats from human activities such as hydropower development, with heavy metal pollution emerging as a critical concern due to altered biogeochemical cycles. Understanding how river damming affects heavy metal transport processes and developing targeted remediation [...] Read more.

Rivers, vital for life and civilizations, face severe threats from human activities such as hydropower development, with heavy metal pollution emerging as a critical concern due to altered biogeochemical cycles. Understanding how river damming affects heavy metal transport processes and developing targeted remediation strategies are essential for safeguarding the health of river-reservoir ecosystems and enabling the sustainable utilization of hydropower resources. Therefore, this review first summarizes the global hydropower development, details how damming disrupts hydrology, environments, and ecosystems, and analyzes heavy metal distribution and transport in reservoir water, suspended sediments, and riverbed sediments. It reveals that river damming promotes heavy metal adsorption onto suspended particles, deposition in riverbed sediments, and re-release during reservoir regulation, and anthropogenic activities are a primary driver of significant pollution in key reservoirs worldwide. Additionally, we further evaluate in situ (e.g., stabilizing agents, sediment capping, and phytoremediation) and ex situ (e.g., dredging, chemical washing, electrochemical separation, and ultrasonic extraction) remediation techniques, highlighting the challenges of phytoremediation in deep, stratified reservoir environments. Moreover, solidification/stabilization emerges as a promising in situ strategy, emphasizing the need for specific approaches to balance pollution control with hydropower functionality in dammed river systems. Full article

(This article belongs to the Special Issue Geochemistry and Removal of Heavy Metals and Other Pollutants in Water)

► Show Figures

Figure 1

19 pages, 5083 KB

Open AccessArticle

Integrating Fungal-Assisted Microalgal Harvesting for Sustainable Treatment and Resource Recovery from Wastewater

by Ayesha Algade Amadu, Daniel Oduro-Mensah, Shuang Qiu, Abdul-Wahab Abbew, Mengting Li, Xiyang Lu, Gabriel Komla Ameka, Mike Yaw Osei-Atweneboana, Mark Osa Akrong, Jacob Kwaku Donkor and Shijian Ge

Water 2025, 17(19), 2832; https://doi.org/10.3390/w17192832 (registering DOI) - 27 Sep 2025

Abstract

Microalgae cultivation is often limited by the high cost and inefficiency of harvesting, making it a major barrier to large-scale resource recovery. Traditional methods such as centrifugation or chemical flocculation are expensive and environmentally unsustainable. As a biological alternative, filamentous fungi can form [...] Read more.

Microalgae cultivation is often limited by the high cost and inefficiency of harvesting, making it a major barrier to large-scale resource recovery. Traditional methods such as centrifugation or chemical flocculation are expensive and environmentally unsustainable. As a biological alternative, filamentous fungi can form pellets or hyphal networks that entrap microalgae cells via bio-flocculation, facilitating easier separation from the culture medium. This study aimed to optimize culture conditions for fungal pellet formation and develop effective microalgae–fungal composites for improved harvesting. Fungal isolates including Aspergillus niger, A. fumigatus, A. flavus, and unidentified strains were screened for their pelleting capacity and nutrient removal efficiency. Through OVAT analysis, key factors such as pH, agitation speed, carbon source, and C:N ratio were found to significantly influence pellet formation. One isolate (FP) showed strong potential, forming pellets under stationary conditions and performing best at neutral to alkaline pH. Molecular analysis identified FP as a fungal consortium containing members of Ascomycota, Mucoromycota, Basidiomycota, and Rozellomycota. When applied to cocoa pulp wastewater, the microalgae–fungi composites outperformed monocultures in reducing NH₄⁺-N, COD, and PO₄³⁻-P. Interestingly, microalgae delayed fungal sporulation. These findings highlight the potential of fungal consortia in enhancing both microalgae harvesting and wastewater bioremediation. Full article

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

► Show Figures

Figure 1

23 pages, 5227 KB

Open AccessArticle

The Simulation of Sediment Transport and the Determination of the Total Volume of Alluvium Using MIKE 21 Software—Case Study: The Șolea Stream (Vâlsan Basin), Romania

by Ionuț-Mădălin Costinescu, Alexandru Nedelea, Daniela Sârbu, Maria Chevereșan and Laura Comănescu

Water 2025, 17(19), 2831; https://doi.org/10.3390/w17192831 - 26 Sep 2025

Abstract

This study presents a methodology for extracting precise insights on sediment transport in the minor bed of a watercourse using MIKE 21 hydrodynamic modelling software. By integrating geotechnical, geomorphological, and hydrological datasets with a good-resolution Digital Terrain Model (DTM), sediment quantities along a [...] Read more.

This study presents a methodology for extracting precise insights on sediment transport in the minor bed of a watercourse using MIKE 21 hydrodynamic modelling software. By integrating geotechnical, geomorphological, and hydrological datasets with a good-resolution Digital Terrain Model (DTM), sediment quantities along a 4.9 km stretch of the Șolea stream—spanning from its source to its confluence with the Vâlsan River (Argeș hydrographic basin)—were determined. A three-month simulation using MIKE 21’s “Mud Transport Module” enabled the comparison of pre- and post-simulation terrain models, yielding detailed information on sediment distribution across the riverbed. These results offer predictive capabilities regarding erosional dynamics and inform mitigation measures to address sedimentary erosion within the study area. The study also presents proposals for land reclamation necessary to prevent the degradation of the riverbed and slopes, such as gabion retaining walls and check dams in the riverbed. Full article

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

13 pages, 1173 KB

Open AccessArticle

Geochemical and Mineralogical Characterisation of Carbonate-Rich Lake Sediments from Lake Kolon, Hungary

by Tamás Zsolt Vári, Gábor Bozsó, Pál Sümegi and Elemér Pál-Molnár

Water 2025, 17(19), 2830; https://doi.org/10.3390/w17192830 - 26 Sep 2025

Abstract

The Danube–Tisza Interfluve in central Hungary, a key region for Quaternary paleoenvironmental reconstruction, hosts ephemeral saline lakes that serve as highly sensitive archives of past climate variability but are increasingly threatened by desertification. Carbonate-rich lacustrine deposits within these systems form through a complex [...] Read more.

The Danube–Tisza Interfluve in central Hungary, a key region for Quaternary paleoenvironmental reconstruction, hosts ephemeral saline lakes that serve as highly sensitive archives of past climate variability but are increasingly threatened by desertification. Carbonate-rich lacustrine deposits within these systems form through a complex interplay of biogenic CO₂ uptake and inorganic precipitation driven by evaporation. To refine paleoenvironmental reconstructions from these archives, a lacustrine sediment core was analysed using XRPD for mineralogy and XRF for major and trace element geochemistry. The results reveal four distinct environmental phases: a cold, siliciclastic-dominated Late Glacial period (c. 23,600–13,400 cal BP); an abrupt shift to massive autogenic carbonate production during the warmer Late Glacial Interstadial, which was also marked by intense aeolian activity (Zr enrichment); the development of a Holocene fen (from c. 11,200 cal BP) with fluctuating hydrology; and a recent interval (from c. 800 cal BP) showing extreme enrichment in phosphorus, lead, and sulphur from anthropogenic sources. Full article

(This article belongs to the Special Issue Carbon Storage in Lake Sediments Under Climate Change)

20 pages, 3590 KB

Open AccessArticle

Effect of Relative Wavelength on Excess Pore Water Pressure in Silty Seabeds with Different Initial Consolidation Degrees

by Hongyi Li, Yaqi Zhang, Aidong Ma, Mingzheng Wen, Zixi Zhao and Shaotong Zhang

Water 2025, 17(19), 2829; https://doi.org/10.3390/w17192829 - 26 Sep 2025

Abstract

Wave-induced silty seabed liquefaction is one of the key threats to offshore infrastructure stability. The excess pore pressure (EPP) response is the key parameter for judging seabed liquefaction. Many studies have examined the EPP response to surface waves in initially well-consolidated seabed; few [...] Read more.

Wave-induced silty seabed liquefaction is one of the key threats to offshore infrastructure stability. The excess pore pressure (EPP) response is the key parameter for judging seabed liquefaction. Many studies have examined the EPP response to surface waves in initially well-consolidated seabed; few works have explored initially less-consolidated seabed, which is widely distributed in estuaries due to the massive river sediment discharge and, thereafter, rapid accumulation. Here, we investigate the EPP response of silty seabed with various initial consolidation degrees using wave flume experiments. We found that (1) in initially liquefied seabed, the EPP magnitude monotonically increases with wavelength, while in initially consolidated seabed, there is a maximal response wavelength which is inversely related to consolidation degree. (2) Furthermore, we found two opposite EPP responses to cyclic surface wave loading under varying seabed conditions in initially liquefied and consolidated seabeds. That is, under the same waves, the EPP magnitude is inversely related to the consolidation degree in initially liquefied seabed, while the EPP magnitude is positively related to the consolidation degree in initially consolidated seabed. In other words, the influence of initial seabed consolidation degree on EPP magnitude behaves like a “√” shaped curve. Our findings provide some implications for further understandings of wave-induced silty seabed liquefaction. Full article

(This article belongs to the Special Issue Advanced Research on Marine Geology and Sedimentology)

► Show Figures

Figure 1

18 pages, 3861 KB

Open AccessArticle

Studies on the Migration of Metal Ions in the Aquifer and the Seepage Prevention of Intercepting Walls in Lead–Zinc Mining Areas

by Shuangcheng Tang, Xuehai Fu, Haiyue Lin, Zexuan Liao, Baolei Xie, Zhiwen Xue, Guanyu Zhao, Wei Qiao and Qiqing Wang

Water 2025, 17(19), 2828; https://doi.org/10.3390/w17192828 (registering DOI) - 26 Sep 2025

Abstract

As metal resource extraction increases, heavy metal ion pollution in the saturated zone intensifies. Hence, research on the migration of heavy metal ions in aquifers and the efficacy of protective measures is essential to inform pollution prevention and control engineering. This study focuses [...] Read more.

As metal resource extraction increases, heavy metal ion pollution in the saturated zone intensifies. Hence, research on the migration of heavy metal ions in aquifers and the efficacy of protective measures is essential to inform pollution prevention and control engineering. This study focuses on the slag pond and its surrounding area of a smelting plant. Utilizing field hydrological surveys and experiments, and data from previous studies, we employed FEFLOW7.0 simulation software to model the groundwater system of the boulder aquifer in this region. The model divides the domain based on natural topography: the eastern river serves as a constant-head boundary, while other areas are set as specified-flux boundaries. The impermeable layer at the bottom is treated as a no-flow boundary, with a maximum simulation period of 2500 days. The simulation examines the natural movement of zinc ions and how the construction of the wall impacts their migration, as well as the wall’s effectiveness in preventing seepage. Findings indicate that the movement of zinc ions is significantly influenced by the reaction coefficient. When the reaction coefficient exceeds 10⁻⁸ s⁻¹, zinc ions decrease rapidly in the area. After the construction of the cutoff wall, the maximum migration distance of zinc ions within 2500 days decreased from 220 m to 77 m, demonstrating its effectiveness in controlling zinc transport in groundwater. Full article

(This article belongs to the Section Hydrogeology)

18 pages, 5020 KB

Open AccessArticle

Assessment of Wetlands in Liaoning Province, China

by Yu Zhang, Chunqiang Wang, Cunde Zheng, Yunlong He, Zhongqing Yan and Shaohan Wang

Water 2025, 17(19), 2827; https://doi.org/10.3390/w17192827 - 26 Sep 2025

Abstract

In recent years, under the dual pressures of climate change and human activities, wetlands in Liaoning Province, China, are increasingly threatened, raising concerns about regional ecological security. To better understand these changes, we developed a vulnerability assessment framework integrating a 30 m wetland [...] Read more.

In recent years, under the dual pressures of climate change and human activities, wetlands in Liaoning Province, China, are increasingly threatened, raising concerns about regional ecological security. To better understand these changes, we developed a vulnerability assessment framework integrating a 30 m wetland dataset (2000–2020) with multi-source environmental and socio-economic data. Using the XGBoost–SHAP model, we analyzed wetland spatiotemporal evolution, driving mechanisms, and ecological vulnerability. Results show the following: (1) ecosystem service functions exhibited significant spatiotemporal differentiation; carbon storage has generally increased, water conservation capacity has significantly improved in the northern region, while wind erosion control and soil retention functions have declined due to urban expansion and agricultural development; (2) driving factors had evolved dynamically, shifting from population density in the early period to increasing influences of precipitation, vegetation index, GDP, and wetland area in later years; (3) ecologically vulnerable areas demonstrated a pattern of fragmented patches coexisting with zonal distribution, forming a three-level spatial gradient of ecological vulnerability—high in the north, moderate in the central region, and low in the southeast. These findings demonstrate the cascading effects of natural and human drivers on wetland ecosystems, and provide a sound scientific basis for targeted conservation, ecological restoration, and adaptive management in Liaoning Province. Full article

(This article belongs to the Special Issue Impacts of Climate Change & Human Activities on Wetland Ecosystems)

35 pages, 7061 KB

Open AccessArticle

Monitoring Surface Water Dynamics in Mining Areas Using Remote Sensing Indices: A Review and Cross-Case Analysis

by Aleksandra Smentek, Aleksandra Kaczmarek, Pinar Eksert and Jan Blachowski

Water 2025, 17(19), 2826; https://doi.org/10.3390/w17192826 - 26 Sep 2025

Abstract

Mining affects groundwater and surface water both during an active mining operation and after its termination. Continuous monitoring and both quantitative and qualitative assessment of water dynamics are crucial for the sustainable management of the mining and post-mining environment. This paper provides an [...] Read more.

Mining affects groundwater and surface water both during an active mining operation and after its termination. Continuous monitoring and both quantitative and qualitative assessment of water dynamics are crucial for the sustainable management of the mining and post-mining environment. This paper provides an extensive overview of water in the mining industry and of remote sensing methods for surface water monitoring. Moreover, selected spectral water indices are compared to assess their performance and usefulness in surface water monitoring. The Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and Modified Normalized Difference Water Index (MNDWI) are applied to different case study areas affected by mining-induced multitemporal surface water changes. All the selected indices were found useful as proxies for surface water identification; however, their effectiveness and accuracy varied in subsequent case studies. Full article

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

► Show Figures

Figure 1

21 pages, 5451 KB

Open AccessArticle

Digital Economic Development Benefits Water Environmental Quality in the Yellow River Basin

by Hui Zhang, Ruining Jia, Rui Xia, Yan Chen, Kai Zhang and Junde Ming

Water 2025, 17(19), 2825; https://doi.org/10.3390/w17192825 - 26 Sep 2025

Abstract

The digital economy, as an advanced economic form, exerts a profound yet unclear influence on water environmental quality within large-scale watersheds. Focusing on the Yellow River Basin (YRB), the second-largest river in China, this study investigates this complex relationship. We developed a novel [...] Read more.

The digital economy, as an advanced economic form, exerts a profound yet unclear influence on water environmental quality within large-scale watersheds. Focusing on the Yellow River Basin (YRB), the second-largest river in China, this study investigates this complex relationship. We developed a novel dual-engine coupling model integrating Support Vector Machines (SVM) and Light Gradient Boosting Machines (LightGBM) to establish comprehensive multi-input, multi-output linkages between digital economy indicators and water quality parameters. Results show that (1) There are notable spatial disparities and synergies in the basin, regions with more developed digital economy generally have better water environmental quality. (2) The SVM model effectively captures the complex spatial relationship between digital economy inputs and water quality outputs, with an average training accuracy above 0.80 and average validation accuracy above 0.70, indicating that digital economy variables are sensitive to water quality changes. (3) The LightGBM model identifies key driving factors and contributions, revealing that digital industrialization has a more significant impact on water quality improvement than industrial digitization. Thus, digital industrialization is a crucial pathway for green transformation in large—scale catchments. Full article

(This article belongs to the Special Issue Water Environment Pollution and Control, 4th Edition)

► Show Figures

Figure 1

20 pages, 15838 KB

Open AccessArticle

The Application of Baseflow Separation and Master Recession Curves Methods in the Middle Yellow River Basins

by Haoxu Tong and Li Wan

Water 2025, 17(19), 2824; https://doi.org/10.3390/w17192824 - 26 Sep 2025

Abstract

Baseflow is the part of the groundwater aquifer that replenishes surface streamflow and is one of the main components of studying the interaction between groundwater and surface water. It is a key factor in maintaining the healthy development of basin ecosystems and is [...] Read more.

Baseflow is the part of the groundwater aquifer that replenishes surface streamflow and is one of the main components of studying the interaction between groundwater and surface water. It is a key factor in maintaining the healthy development of basin ecosystems and is of great significance for promoting the sustainable utilization and scientific management of water resources. However, the understanding of runoff and baseflow in the MYRB is still unclear, and the relationship between streamflow and baseflow has not been fully grasped. At the same time, there is currently no water balance function applicable to the MYRB. In order to solve the above problems, this article uses digital filtering methods to segment the baseflow and the MRC method to construct the main recession curve. The baseflow rate of MYRB was calculated, and the water balance function applicable to MYRB was found. The results obtained are as follows: the average annual baseflow index values for different basins were 0.81, 0.76, 0.81, 0.82, 0.79, and 0.79, respectively. The fitting of the Boussinesq function, the Maillet function, and the Brutsaert and Nieber function was significantly better than the other two functions. Full article

(This article belongs to the Section Hydrogeology)

► Show Figures

Figure 1

18 pages, 3079 KB

Open AccessArticle

Optimizing Water–Sediment, Ecological, and Socioeconomic Management in Cascade Reservoirs in the Yellow River: A Multi-Target Decision Framework

by Donglin Li, Rui Li, Gang Liu and Chang Zhang

Water 2025, 17(19), 2823; https://doi.org/10.3390/w17192823 - 26 Sep 2025

Abstract

Multi-target optimization management of reservoirs plays a crucial role in balancing multiple scheduling objectives, thereby contributing to watershed sustainability. In this study, a model was developed for the multi-target optimization scheduling of water–sediment, ecological, and socioeconomic objectives of reservoirs with multi-dimensional scheduling needs, [...] Read more.

Multi-target optimization management of reservoirs plays a crucial role in balancing multiple scheduling objectives, thereby contributing to watershed sustainability. In this study, a model was developed for the multi-target optimization scheduling of water–sediment, ecological, and socioeconomic objectives of reservoirs with multi-dimensional scheduling needs, including flood control, sediment discharge, ecological protection, and socio-economic development. After obtaining the Pareto solution set by solving the optimization model, a decision model based on cumulative prospect theory (CPT) was constructed to select optimal scheduling schemes, resulting in the development of a multi-target decision framework for reservoirs. The proposed framework not only mitigates multi-target conflicts among water–sediment, ecological, and socioeconomic objectives but also quantifies the different preferences of decision-makers. The framework was then applied to six cascade reservoirs (Longyangxia, Liujiaxia, Haibowan, Wanjiazhai, Sanmenxia, and Xiaolangdi) in the Yellow River basin of China. A whole-river multi-target decision model was developed for water–sediment, ecological, and socioeconomic objectives, and the cooperation–competition dynamics among multiple objectives and decision schemes were analyzed for wet, normal, and dry years. The results demonstrated the following: (1) sediment discharge goals and ecological goals were somewhat competitive, and sediment discharge goals and power generation goals were highly competitive, while ecological goals and power generation goals were cooperative, and cooperation–competition relationships among the three objectives was particularly pronounced in dry years; (2) the decision plans for abundant, normal, and low water years were S293, S241, and S386, respectively, and all are consistent with actual dispatch conditions; (3) compared to local models, the whole-river multi-target scheduling model achieved increases of 71.01 × 10⁶ t in maximum sediment discharge, 0.72% in maximum satisfaction rate of suitable ecological flow, and 0.20 × 10⁹ kW·h in maximum power generation; and (4) compared to conventional decision methods, the CPT-based approach yielded rational results with substantially enhanced sensitivity, indicating its suitability for selecting and decision-making of various schemes. This study provides insights into the establishment of multi-target dispatching models for reservoirs and decision-making processes for scheduling schemes. Full article

(This article belongs to the Special Issue Yellow River Basin Management Under Pressure: Present State, Restoration and Protection, 4th Edition)

► Show Figures

Figure 1

22 pages, 6065 KB

Open AccessArticle

A Sustainability Evaluation of Large-Scale Water Network Projects: A Case Study of the Jiaodong Water Network Project, China

by Yue Qiu and Changshun Liu

Water 2025, 17(19), 2822; https://doi.org/10.3390/w17192822 - 26 Sep 2025

Abstract

Large-scale water network projects are a crucial approach for the rational allocation of water resources and addressing water resource crises. Reliable sustainability evaluation is essential to ensure the sustainable operation of large-scale water network projects. This study develops an improved Fuzzy Comprehensive Evaluation [...] Read more.

Large-scale water network projects are a crucial approach for the rational allocation of water resources and addressing water resource crises. Reliable sustainability evaluation is essential to ensure the sustainable operation of large-scale water network projects. This study develops an improved Fuzzy Comprehensive Evaluation (FCE) method based on Game Theory weight fusion (GWF) for the quantitative evaluation of the sustainability of water network projects. By combining the Analytic Hierarchy Process (AHP), Entropy Weight Method (EWM), and Game Theory approach, the study integrates the advantages of both subjective and objective weighting methods to achieve the allocation of indicator weights; the sustainability of the Jiaodong Water Network Project was quantitatively evaluated by employing the improved FCE method. The results indicate that the resource and management dimensions are the two most critical factors affecting the sustainability of large-scale water network projects. Indicators with high weight such as per capita water resources, the rationality of the management system, and level of management intelligence are the primary risk factors affecting the sustainable operation of large-scale water network projects. The sustainability evaluation value of the Jiaodong Water Network Project is 82.83 points, which is classified as “high” sustainability. This validates the reliability of the evaluation indicator system and the method used. Full article

(This article belongs to the Section Hydrology)

► Show Figures

Figure 1

19 pages, 5264 KB

Open AccessArticle

Integrated Allocation of Water-Sediment Resources and Its Impacts on Socio-Economic Development and Ecological Systems in the Yellow River Basin

by Lingang Hao, Enhui Jiang, Bo Qu, Chang Liu, Jia Jia, Ying Liu and Jiaqi Li

Water 2025, 17(19), 2821; https://doi.org/10.3390/w17192821 - 26 Sep 2025

Abstract

Both water and sediment resource allocation are critical for achieving sustainable development in sediment-laden river basins. However, current understanding lacks a holistic perspective and fails to capture the inseparability of water and sediment. The Yellow River Basin (YRB) is the world’s most sediment-laden [...] Read more.

Both water and sediment resource allocation are critical for achieving sustainable development in sediment-laden river basins. However, current understanding lacks a holistic perspective and fails to capture the inseparability of water and sediment. The Yellow River Basin (YRB) is the world’s most sediment-laden river, characterized by pronounced ecological fragility and uneven socio-economic development. This study introduces integrated water-sediment allocation frameworks for the YRB based on the perspective of the water-sediment nexus, aiming to regulate their impacts on socio-economic and ecological systems. The frameworks were established for both artificial units (e.g., irrigation zones and reservoirs) and geological units (e.g., the Jiziwan region, lower channels, and estuarine deltas) within the YRB. The common feature of the joint allocation of water and sediment across the five units lies in shaping a coordinated water–sediment relationship, though their focuses differ, including in-stream water-sediment processes and combinations, the utilization of water and sediment resources, and the constraints imposed by socio-economic and ecological systems on water-sediment distribution. In irrigation zones, the primary challenge lies in engineering-based control of inflow magnitude and spatiotemporal distribution for both water and sediment. In reservoir systems, effective management requires dynamic regulation through density current flushing and coordinated operations to achieve water-sediment balance. In the Jiziwan region, reconciling socio-economic development with ecological integrity requires establishing science-based thresholds for water and sediment use while ensuring a balance between utilization and protection. Along the lower channel, sustainable management depends on delineating zones for human activities and ecological preservation within floodplains. For deltaic systems, key strategies involve adjusting upstream sediment and refining depositional processes. Full article

(This article belongs to the Special Issue Resilient Rivers: Integrating Nature-Based Solutions with Hydraulic Engineering)

► Show Figures

Figure 1

58 pages, 4032 KB

Open AccessArticle

Potential Applications of Light Absorption Coefficients in Assessing Water Optical Quality: Insights from Varadero Reef, an Extreme Coral Ecosystem

by Stella Patricia Betancur-Turizo, Adán Mejía-Trejo, Eduardo Santamaria-del-Angel, Yerinelys Santos-Barrera, Gisela Mayo-Mancebo and Joaquín Pablo Rivero-Hernández

Water 2025, 17(19), 2820; https://doi.org/10.3390/w17192820 - 26 Sep 2025

Abstract

Coral reefs exposed to chronically turbid conditions challenge conventional assumptions about the optical environments required for reef persistence and productivity. This study investigates the utility of light absorption coefficients as indicators of optical water quality in Varadero Reef, an extreme coral ecosystem located [...] Read more.

Coral reefs exposed to chronically turbid conditions challenge conventional assumptions about the optical environments required for reef persistence and productivity. This study investigates the utility of light absorption coefficients as indicators of optical water quality in Varadero Reef, an extreme coral ecosystem located in Cartagena Bay, Colombia. Field campaigns were conducted across three seasons (rainy, dry, and transitional) along a transect from fluvial to marine influence. Absorption coefficients at 440 nm were derived for particulate (a_p(440)) and chromophoric dissolved organic matter (a_CDOM(440)) to assess their contribution to underwater light attenuation. Average values across seasons show that a_p(440) reached 0.466 m⁻¹ in the rainy season (September 2021), 0.285 m⁻¹ in the dry season (February 2022), and 0.944 m⁻¹ in the transitional rainy season (June 2022). Meanwhile, mean a_CDOM(440) values were 0.368, 0.111, and 0.552 m⁻¹, respectively. These coefficients reflect the dominant influence of particulate absorption under turbid conditions and increasing a_CDOM(440) relevance during lower turbidity periods. Mean Secchi Disk Depth (ZSD) ranged from 0.6 m in the rainy season to 3.0 m in the dry season, aligning with variations in Kd PAR, which averaged 2.63 m⁻¹, 1.13 m⁻¹, and 1.08 m⁻¹ for the three campaigns. Chlorophyll-a concentrations at 1 m depth also varied significantly, with average values of 2.3, 2.7, and 6.2 μg L⁻¹, indicating phytoplankton biomass peaks associated with seasonal freshwater inputs. While particulate absorption limits light penetration, CDOM plays a potentially photoprotective role by attenuating UV radiation. The observed variability in these optical constituents reflects complex hydrodynamic and environmental gradients, providing insight into the mechanisms that sustain coral functionality under suboptimal light conditions. The absorption-based approach applied here, using standardized spectrophotometric methods, proved to be a reliable and reproducible tool for characterizing the spatial and temporal variability of IOPs. We propose integrating these indicators into monitoring frameworks as cost-effective, component-resolving tool for evaluating light regimes and ecological resilience in optically dynamic coastal systems. Full article

(This article belongs to the Special Issue Study on Environmental Hydrology and Hydrodynamic Characteristics of Basins, Estuaries and Offshore)

► Show Figures

Figure 1

29 pages, 1446 KB

Open AccessReview

Review of Water Use Assessment in Livestock Production Systems and Supply Chains

by Katrin Drastig and Ranvir Singh

Water 2025, 17(19), 2819; https://doi.org/10.3390/w17192819 - 25 Sep 2025

Abstract

Improving the water productivity and sustainability of global food supplies and reducing water stress worldwide requires a comprehensive and consistent assessment of water use in global food production systems, including livestock production and supply chains. Presented here is a systematic review of relevant [...] Read more.

Improving the water productivity and sustainability of global food supplies and reducing water stress worldwide requires a comprehensive and consistent assessment of water use in global food production systems, including livestock production and supply chains. Presented here is a systematic review of relevant livestock water use studies, published over two periods: “Period 1993–2017” and “Period 2018–2024”, assessing consistency in their approaches and identifying opportunities for advancing and harmonizing the assessment of livestock water use worldwide. However, the review highlights that a comprehensive and consistent assessment of livestock water use remains a challenge. The reviewed studies (a total of 317) differ in terms of their accounting of different water flows, setting the system boundaries, and quantification of water productivity and impact metrics. This makes it difficult to compare potential water productivity and environmental impacts of livestock production systems at different scales and locations. Case studies are required to further develop and implement a robust and consistent methodological approach, based on locally calibrated models and databases, of different livestock production systems in different agroclimatic conditions. Also, further communication and training are required to help build the capability to apply a comprehensive and consistent assessment of livestock water use locally and globally. The adoption of a scientifically robust and practically applicable methodological framework will support researchers, policy managers, farmers, and business leaders in sound decision-making to improve the productivity and sustainability of water use in livestock production systems locally and globally. Full article

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

► Show Figures

Figure 1

19 pages, 4745 KB

Open AccessBrief Report

Optimizing Shrimp Culture Through Environmental Monitoring: Effects of Water Quality and Metal Ion Profile on Whiteleg Shrimp (Litopenaeus vannamei) Performance in a Semi-Intensive Culture Pond

by Muhammad Farhan Nazarudin, Mohammad Amirul Faiz Zulkiply, Muhammad Hasif Samsuri, Nurul Aina Syakirah Khairil Anwar, Nur Syamimie Afiqah Jamal, Norfarrah Mohamed Alipiah, Mohd Ihsanuddin Ahmad, Norhariani Mohd Nor, Ina Salwany Md Yasin, Natrah Ikhsan, Mohammad Noor Amal Azmai and Mohd Hafiz Rosli

Water 2025, 17(19), 2818; https://doi.org/10.3390/w17192818 (registering DOI) - 25 Sep 2025

Abstract

Water quality management is crucial for sustainable whiteleg shrimp (Litopenaeus vannamei) aquaculture, though little research has comprehensively investigated the spatiotemporal fluctuation of trace elements in tropical semi-intensive ponds. This study investigated the water quality variations and trace element concentrations in an [...] Read more.

Water quality management is crucial for sustainable whiteleg shrimp (Litopenaeus vannamei) aquaculture, though little research has comprehensively investigated the spatiotemporal fluctuation of trace elements in tropical semi-intensive ponds. This study investigated the water quality variations and trace element concentrations in an earthen pond across a 56-day culture cycle during the dry season. Physicochemical parameters (temperature, pH, salinity, dissolved oxygen, ammonia, nitrite, and nitrate) and trace elements (Cu, Zn, Mn, Fe, and Mg) were measured concurrently with shrimp growth and survival. The DO and pH readings were observed to fluctuate significantly during the mid-to-late stages of culture, with DO nearing critical thresholds (<5.0 mg L⁻¹). A sudden increase in ammonia and nitrite levels suggested the accumulation of organic matter and a microbial imbalance. Zinc concentrations (0.28–1.00 mg L⁻¹) approached stress-inducing levels, while magnesium remained low (10.44–10.72 mg L⁻¹). Pearson’s correlation revealed strong positive associations between ammonia and nitrate (r = 0.95) and between DO and pH (r = 0.94), while Mg was negatively correlated with Fe (r = −0.99) and nitrite (r = −0.88). Shrimp achieved 13.43 ± 0.73 g mean weight, with 77.8% survival and an FCR of 1.08. These results provide baseline evidence that combined water quality and trace element monitoring can become an early warning framework for pond management. Future studies integrating shrimp physiology and immune responses are needed to establish direct causal relationships. Full article

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

► Show Figures

Figure 1

25 pages, 6644 KB

Open AccessArticle

Organoclay Microparticle-Enhanced Microfiltration for the Removal of Acid Red 27 in Aqueous Systems

by Tulio A. Lerma, Andrés Felipe Chamorro, Manuel Palencia, Enrique Combatt and Hernán Valle

Water 2025, 17(19), 2817; https://doi.org/10.3390/w17192817 - 25 Sep 2025

Abstract

The microparticle-enhanced microfiltration is a technique that combines the use of microparticulate adsorbent material dispersed in aqueous solution and microfiltration membranes for the removal of ions and emerging contaminants with low energy consumption. Thus, the objective of this work was to synthesize an [...] Read more.

The microparticle-enhanced microfiltration is a technique that combines the use of microparticulate adsorbent material dispersed in aqueous solution and microfiltration membranes for the removal of ions and emerging contaminants with low energy consumption. Thus, the objective of this work was to synthesize an organoclay, BAPTES, based on bentonite and (3-aminopropyl)triethoxysilane for use as a semi-synthetic adsorbent material in the microparticle-enhanced microfiltration process for the removal of AR27 in aqueous systems. For this purpose, the obtained organoclay was structurally characterized by FTIR-ATR-FEDS, SEM-EDS, DLS, and thermal analysis. In addition, equilibrium adsorption and kinetic studies of AR27 were performed. The results showed a significant increase in the adsorption capacity of AR27 by organoclay (86.06%) compared to natural bentonite (2.10%), due to the presence of ionizable amino groups in the organoclay structure that promote electrostatic interactions with the dye. Furthermore, kinetic studies showed that the adsorption process follows a pseudo-first-order model and that the equilibrium data better fits the Temkin model, indicating a heterogeneous adsorption surface with different binding energies. The evaluation of enhanced microfiltration with BAPTES microparticles showed that the adsorption capacity obtained in continuous flow experiments (14.25–33.63 mg g⁻¹) was lower than that determined experimentally under equilibrium conditions (~39.5 mg g⁻¹), suggesting that the residence time of the analyte and the adsorbent in the filtration cell is a determining factor in the retention values obtained. In addition, desorption studies revealed that basic pH had a greater effect than the presence of salts and the use of ethanol, favoring the weakening of the AR27-BAPTES interaction. Finally, the results highlight the potential use of BAPTES microparticle-enhanced microfiltration in applications involving the treatment of contaminated industrial effluents. Full article

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

► Show Figures

Figure 1

48 pages, 12849 KB

Open AccessArticle

Analysis of the Functional Efficiency of a Prototype Filtration System Dedicated for Natural Swimming Ponds

by Wojciech Walczak, Artur Serafin, Tadeusz Siwiec, Jacek Mielniczuk and Agnieszka Szczurowska

Water 2025, 17(19), 2816; https://doi.org/10.3390/w17192816 - 25 Sep 2025

Abstract

Water treatment systems in swimming ponds support the natural self-cleaning capabilities of water based on the functions of repository macrophytes in their regeneration zone and the regulation of the internal metabolism of the reservoirs. As part of the project, a functional modular filtration [...] Read more.

Water treatment systems in swimming ponds support the natural self-cleaning capabilities of water based on the functions of repository macrophytes in their regeneration zone and the regulation of the internal metabolism of the reservoirs. As part of the project, a functional modular filtration chamber with system multiplication capabilities was designed and created. This element is dedicated to water treatment systems in natural swimming ponds. The prototype system consisted of modular filtration chambers and pump sections, as well as equipment adapted to the conditions prevailing in the eco-pool. An innovative solution for selective shutdown of the filtration chamber without closing the circulation circuit was also used, which forms the basis of a patent application. A verified high-performance adsorbent, Rockfos^® modified limestone, was used in the filtration chamber. In order to determine the effective filtration rate for three small test ponds with different flow rates (5 m/h, 10 m/h and 15 m/h), the selected physicochemical parameters of water (temperature, pH, electrolytical conductivity, oxygen saturation, total hardness, nitrites, nitrates, and total phosphorus, including adsorption efficiency and bed absorption capacity) were researched before and after filtration. Tests were also carried out on the composition of fecal bacteria and phyto- and zooplankton. Based on high effective phosphorus filtration efficiency of 32.65% during the operation of the bed, the following were determined: no exceedances of the standards for the tested parameters in relation to the German standards for eco-pools (FLL—Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e. V., 2011); lower number of fecal pathogens (on average 393—coliform bacteria; 74—Escherichia coli; 34—fecal enterococci, most probably number/100 mL); the lowest share of problematic cyanobacteria in phytoplankton (<250,000 individuals/dm³ in number and <0.05 µg/dm³—biomass); low chlorophyll a content (2.2 µg/dm³—oligotrophy) and the presence of more favorable smaller forms of zooplankton, an effective filtration speed of 5 m/h. This velocity was recommended in the FLL standards for swimming ponds, which were adopted in this study as a reference for rapid filters. In testing the functional efficiency of a dedicated filtration system for a Type II test pond (50 m²—area and 33 m³—capacity), at a filtration rate of 5 m/h, an average effective phosphorus adsorption efficiency of 18.28–53.98% was observed under the bed work-in-progress conditions. Analyses of other physicochemical water parameters, with appropriate calculations and statistical tests, indicated progressive functional efficiency of the system under bathing conditions. Full article

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

► Show Figures

Figure 1

18 pages, 3328 KB

Open AccessArticle

Hydrochemical Controlling Factors and Spatial Distribution Characteristics of Shallow Groundwater in Agricultural Regions of Central-Eastern Henan Province, China

by Peng Guo, Shaoqing Chen, Xiaosheng Luo, Kelin Hu and Baoguo Li

Water 2025, 17(19), 2815; https://doi.org/10.3390/w17192815 - 25 Sep 2025

Abstract

Groundwater serves as a vital water resource for agricultural irrigation and domestic use in farmland areas. Its chemical composition is jointly influenced by agricultural fertilization, land use practices, and natural geological processes. However, research on the controlling factors and spatial distribution characteristics of [...] Read more.

Groundwater serves as a vital water resource for agricultural irrigation and domestic use in farmland areas. Its chemical composition is jointly influenced by agricultural fertilization, land use practices, and natural geological processes. However, research on the controlling factors and spatial distribution characteristics of groundwater hydrochemistry in agricultural regions remains insufficient. In this study, 56 groundwater samples were collected from the central-eastern plain of Henan Province, China. A combination of hierarchical cluster analysis, ionic ratio methods, principal component analysis, and kriging interpolation was employed to investigate the hydrochemical characteristics, spatial patterns, and primary controlling factors of regional groundwater. The results indicate that the first group of samples is characterized by high total dissolved solids (TDS), elevated Na⁺ and Cl⁻ concentrations, predominantly controlled by evaporation and concentration processes. The second group exhibits high pH and low Ca²⁺ concentrations, mainly influenced by silicate weathering, with reverse cation exchange acting as a secondary controlling process. The third group is characterized by elevated concentrations of Ca²⁺ and NO₃⁻, primarily controlled by carbonate weathering and agricultural activities. The western part of the study area serves as the main groundwater recharge zone and has the highest NO₃⁻ and Ca²⁺ concentrations. In the central area, most ion concentrations are relatively high, forming a distinct gradient with surrounding regions. Meanwhile, the eastern area displays elevated concentrations of HCO₃⁻, TDS, Na⁺, and Cl⁻, highlighting pronounced spatial heterogeneity. Overall, the hydrochemical composition of groundwater in the study area is shaped by both natural processes and anthropogenic activities, exhibiting significant spatial heterogeneity. Notably, the spatial variation of NO₃⁻ concentrations is substantial, indicating that certain localities have already been affected by agricultural non-point source pollution. Full article

(This article belongs to the Section Hydrogeology)

► Show Figures

Figure 1

18 pages, 4277 KB

Open AccessArticle

Synthesis of Zirconium-Based MOF–Biochar Composites for Efficient Congo Red Removal from Industrial Wastewater

by Yufei Zhang and Yifeng He

Water 2025, 17(19), 2814; https://doi.org/10.3390/w17192814 - 25 Sep 2025

Abstract

Organic dye pollution in industrial wastewater is severe and difficult to degrade, posing a significant challenge to environmental management and water resource security. To meet the demand for the efficient elimination of Congo Red (CR) dye from industrial wastewater, this work prepared two [...] Read more.

Organic dye pollution in industrial wastewater is severe and difficult to degrade, posing a significant challenge to environmental management and water resource security. To meet the demand for the efficient elimination of Congo Red (CR) dye from industrial wastewater, this work prepared two zirconium-based metal–organic framework (MOF)–biochar composites, UIO-66@BY and UIO-67@BY, by in situ loading zirconium-based MOFs (UIO-66 and UIO-67) onto biochar (BY) via a solvothermal method. The composite material was comprehensively characterized using transmission electron microscopy (TEM), BET surface area analysis, and X-ray photoelectron spectroscopy (XPS). The adsorption results indicate that UIO-67@BY exhibits a significantly higher maximum adsorption capacity for CR dye compared to pristine biochar (BY), while UIO-66@BY also shows enhanced adsorption performance, but one that is slightly lower than that of UIO-67@BY. Further investigations reveal that the adsorption behavior conformed to a pseudo-second-order kinetic model and was well described by the Langmuir isotherm, suggesting that the adsorbent exhibited a homogeneous adsorption surface, and that chemical adsorption played a dominant role in the process. The primary mechanisms responsible for CR dye uptake by the composite include pore structure characteristics, coordination with functional groups, π–π stacking interactions, and electrostatic forces. The composite material developed herein provides an environmentally sustainable and economically efficient strategy for mitigating wastewater contamination. Full article

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

► Show Figures

Figure 1

28 pages, 1509 KB

Open AccessReview

Life After Adsorption: Regeneration, Management, and Sustainability of PFAS Adsorbents in Water Treatment

by Magdalena Andrunik and Marzena Smol

Water 2025, 17(19), 2813; https://doi.org/10.3390/w17192813 - 25 Sep 2025

Abstract

Per- and polyfluoroalkyl substances (PFASs) represent one of the most challenging classes of persistent organic pollutants, and adsorption is currently one of the most widely deployed method for their removal from water. However, the long-term sustainability of adsorption-based treatment depends on how adsorbents [...] Read more.

Per- and polyfluoroalkyl substances (PFASs) represent one of the most challenging classes of persistent organic pollutants, and adsorption is currently one of the most widely deployed method for their removal from water. However, the long-term sustainability of adsorption-based treatment depends on how adsorbents are regenerated, managed after exhaustion, and integrated into broader environmental and regulatory frameworks. This review synthesises recent advances in regeneration strategies for PFAS-saturated adsorbents, including thermal, solvent-based, chemical, hybrid, and emerging methods, and provides a targeted analysis of policy and regulatory frameworks governing PFAS management in water. Evidence from the literature is critically assessed with attention to regeneration efficiencies, adsorbent stability, secondary waste generation, and long-term reuse potential. Life cycle assessment (LCA) studies are also examined to evaluate the environmental and cost implications of different management options. The analysis highlights that while solvent and chemical regeneration achieve high short-term recovery, thermal processes offer partial destructive potential, and electrochemical methods are emerging as promising but unproven alternatives. Persistent challenges include incomplete PFAS desorption, performance decline over multiple cycles, energy intensity, and secondary waste burdens. Advancing sustainable PFAS treatment requires integrated evaluation frameworks linking technical performance with environmental impact and cost, supported by policy drivers that incentivize regeneration and safe end-of-life management. Full article

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

► Show Figures

Figure 1

28 pages, 6107 KB

Open AccessArticle

Transboundary Management of a Common Sea in the Gulf of Venice: Opportunities from Maritime Spatial Planning in Italy and Slovenia

by Gregor Čok, Martina Bocci, Fabio Carella, Emiliano Ramieri and Manca Plazar

Water 2025, 17(19), 2812; https://doi.org/10.3390/w17192812 - 25 Sep 2025

Abstract

Italy and Slovenia have recently adopted their first Maritime Spatial Plans (MSP). These plans belong to a new generation of spatial planning acts that introduce numerous innovations. This article presents the differences and similarities between the Italian and Slovenian MSP. The aim is [...] Read more.

Italy and Slovenia have recently adopted their first Maritime Spatial Plans (MSP). These plans belong to a new generation of spatial planning acts that introduce numerous innovations. This article presents the differences and similarities between the Italian and Slovenian MSP. The aim is to determine how a new planning approach can support joint spatial development and management in a transboundary perspective with particular reference to the cross-border area of the Gulf of Venice. Descriptive and comparative scientific methods were applied in the study. We analysed the structure of both plans and the content of the individual planning instruments and tools for three key sectors: Fisheries, Maritime Transport and Nature Conservation. We found that both plans offer new opportunities for transboundary spatial coordination and planning, while the process of preparing the plans themselves is particularly important. Both plans provide instruments to address transboundary environmental impacts, spatial development and sectoral management regimes. The implementation tools include provisions on the spatial, temporal and technical conditions for carrying out a particular activity at sea. The Italian plan adopts a strategic approach that offers possibilities for intersectoral and cross-border planning coordination. The Slovenian plan is more detailed and binding. Regardless of individual differences, the adoption of both plans represents a major step towards achieving the common goals of sustainable spatial development in the shared marine area of the Gulf of Venice. Full article

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

► Show Figures

Figure 1

19 pages, 2540 KB

Open AccessArticle

Eco-Friendly Removal of Cationic and Anionic Textile Dyes Using a Low-Cost Natural Tunisian Chert: A Promising Solution for Wastewater Treatment

by Najah Mahjoubi and Raghda Hamdi

Water 2025, 17(19), 2806; https://doi.org/10.3390/w17192806 - 25 Sep 2025

Viewed by 92

Abstract

The discharge of synthetic dyes into aquatic ecosystems stands as a pointed environmental concern, with serious consequences affecting not only biodiversity and water quality but also human health. To address this challenge, this study introduces a natural Tunisian chert, a silica-rich sedimentary rock, [...] Read more.

The discharge of synthetic dyes into aquatic ecosystems stands as a pointed environmental concern, with serious consequences affecting not only biodiversity and water quality but also human health. To address this challenge, this study introduces a natural Tunisian chert, a silica-rich sedimentary rock, as a promising, sustainable, and low-cost adsorbent for treating textile dye-polluted wastewater. For the first time, the adsorption capabilities of a Tunisian chert were systematically evaluated for both cationic (Methylene Blue; MB and Cationic Yellow 28; CY28) and anionic dyes (Eriochrome Black T; EBT). To assess the impacts of key operational parameters, such as pH (2–12), contact time (0–240 min), adsorbent dosage (0.02–0.25 g), and initial dye concentration (50–500 mg/L), batch mode adsorption trials were performed. The Langmuir isotherm model most accurately fits the adsorption data, yielding a maximum adsorption capacity of 138.88 mg/g for MB, 69.93 mg/g for CY28, and 119.04 mg/g for EBT, outperforming multiple conventional adsorbents. Kinetic modeling revealed that adsorption adhered to a pseudo-second-order model, with rapid equilibrium within 45–60 min, highlighting the efficiency of the Tunisian chert. Optimal dye removal was obtained at pH = 8 for cationic dyes and pH = 4 for EBT, driven by electrostatic interactions and surface charge dynamics. The current research work reveals that Tunisian chert is a low-cost and efficient adsorbent with a high potential serving for large-scale industrial applications in wastewater treatment. Using a locally abundant natural resource, this work provides a maintainable and economical approach for dye removal from polluted wastewater. Full article

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

► Show Figures

Figure 1

21 pages, 2064 KB

Open AccessReview

Status and Progress of Determining the Variability and Controls on Chemical Denudation Rates in Glacierized Basins Around the World

by Maya P. Bhatt, Ganesh B. Malla and Jacob C. Yde

Water 2025, 17(19), 2811; https://doi.org/10.3390/w17192811 - 24 Sep 2025

Viewed by 19

Abstract

Glaciers play a crucial role in shaping global hydrology and biogeochemical cycles, yet their climate-forced dynamic impact on chemical denudation and solute yields remain poorly understood. This study compiled data on 40 well-documented cationic denudation rates (CDR) from glaciers across Northwest America, the [...] Read more.

Glaciers play a crucial role in shaping global hydrology and biogeochemical cycles, yet their climate-forced dynamic impact on chemical denudation and solute yields remain poorly understood. This study compiled data on 40 well-documented cationic denudation rates (CDR) from glaciers across Northwest America, the Svalbard/Arctic Canada, Iceland, Greenland, Europe, China-Tibet, Antarctica, and the Himalayas, revealing substantial spatial variability. CDRs ranged from 46 to 4160 meq m⁻² yr⁻¹. Northwest American and Himalayan glaciers exhibited the highest CDRs, with the Himalayan denudation rate exceeding the global average by more than fourfold. The exceptionally high mean chemical weathering intensity (CWI) of 801 meq m⁻³ from the Himalayan glaciers indicate a wide range of geochemical and climatic conditions within the region, while Northwest American and Greenland glaciers show comparatively lower mean intensities (273 and 247 meq m⁻³, respectively) suggesting a consistent geochemical regime. Northwest American glaciers had the highest specific discharge rates, while Svalbard/Arctic Canada glaciers had the lowest, reflecting regional disparities influenced by climatic and geological factors. A Bonferroni post hoc test highlighted significant differences in specific discharge between Northwest American glaciers and two other basins, emphasizing their distinct hydrological behavior. Predictive modeling revealed a statistically significant but weak relationship between CDR and specific discharge (R² = 57%), suggesting that much of the variability in CDR cannot be explained by specific discharge alone. A regression coefficient of 382 meq m⁻² yr⁻¹ indicates that CDR increases with glacier discharge, although basin-specific analyses showed minimal variation in this relationship across regions. Svalbard/Arctic Canada, Antarctic, Greenlandic, Icelandic, and European Alpine glaciers displayed lower CDRs, which varied depending on underlying lithology, with higher rates observed in carbonate and basaltic terrains compared to other lithologies. We hypothesize that glacier retreat enhances the downward progression of the weathering reaction front, increasing CDR, particularly in rapidly retreating glaciers. Full article

(This article belongs to the Special Issue Climate Change Impacts on Water Resources and Ecosystem Dynamics in Mountainous and Cold-Region Ecosystems)

► Show Figures

Figure 1

30 pages, 10855 KB

Open AccessArticle

Hydrochemical Characteristics and Evolution Mechanisms of Shallow Groundwater in the Alluvial–Coastal Transition Zone of the Tangshan Plain, China

by Shiyin Wen, Shuang Liang, Guoxing Pang, Qiang Shan, Yingying Ye, Jianan Zhang, Mingqi Dong, Linping Fu and Meng Wen

Water 2025, 17(19), 2810; https://doi.org/10.3390/w17192810 - 24 Sep 2025

Viewed by 16

Abstract

To elucidate the hydrochemical characteristics and evolution mechanisms of shallow groundwater in the alluvial–coastal transitional zone of the Tangshan Plain, 76 groundwater samples were collected in July 2022. An integrated approach combining Piper and Gibbs diagrams, ionic ratio analysis, multivariate statistical methods (including [...] Read more.

To elucidate the hydrochemical characteristics and evolution mechanisms of shallow groundwater in the alluvial–coastal transitional zone of the Tangshan Plain, 76 groundwater samples were collected in July 2022. An integrated approach combining Piper and Gibbs diagrams, ionic ratio analysis, multivariate statistical methods (including Pearson correlation, hierarchical cluster analysis, and principal component analysis), and PHREEQC inverse modeling was employed to identify hydrochemical facies, dominant controlling factors, and geochemical reaction pathways. Results show that groundwater in the upstream alluvial plain is predominantly of the HCO₃–Ca type with low mineralization, primarily controlled by carbonate weathering, water–rock interaction, and natural recharge. In contrast, groundwater in the downstream coastal plain is characterized by high-mineralized Cl–Na type water, mainly influenced by seawater intrusion, evaporation concentration, and dissolution of evaporite minerals. The spatial distribution of groundwater follows a pattern of “freshwater in the north and inland, saline water in the south and coastal,” reflecting the transitional nature from freshwater to saline water. Ionic ratio analysis reveals a concurrent increase in Na⁺, Cl⁻, and SO₄²⁻ in the coastal zone, indicating coupled processes of saline water mixing and cation exchange. Statistical analysis identifies mineralization processes, carbonate weathering, redox conditions, and anthropogenic inputs as the main controlling factors. PHREEQC simulations demonstrate that groundwater in the alluvial zone evolves along the flow path through CO₂ degassing, dolomite precipitation, and sulfate mineral dissolution, whereas in the coastal zone, continuous dissolution of halite and gypsum leads to the formation of high-mineralized Na–Cl water. This study establishes a geochemical evolution framework from recharge to discharge zones in a typical alluvial–coastal transitional setting, providing theoretical guidance for salinization boundary identification and groundwater management. Full article

(This article belongs to the Section Hydrogeology)

► Show Figures

Figure 1

18 pages, 3715 KB

Open AccessArticle

Ecological Risk Assessment of Storm-Flood Processes in Shallow Urban Lakes Based on Resilience Theory

by Congxiang Fan, Haoran Wang, Yongcan Chen, Wenyan He and Hong Zhang

Water 2025, 17(19), 2809; https://doi.org/10.3390/w17192809 - 24 Sep 2025

Viewed by 24

Abstract

Urban shallow lakes are sentinel ecosystems whose stability is increasingly threatened by acute, sediment-laden storm floods. While chronic nutrient loading has been extensively studied, rapid risk assessment tools for short-pulse disturbances are still missing. Our aim was to develop a resilience-based, process-linked framework [...] Read more.

Urban shallow lakes are sentinel ecosystems whose stability is increasingly threatened by acute, sediment-laden storm floods. While chronic nutrient loading has been extensively studied, rapid risk assessment tools for short-pulse disturbances are still missing. Our aim was to develop a resilience-based, process-linked framework that couples depth-averaged hydrodynamics, advection-diffusion sediment transport and light-driven macrophyte habitat suitability to quantify hour-scale ecological risk and week-scale recovery. The ecological risk model integrates a depth-averaged hydrodynamic module, an advection–diffusion sediment transport routine, and species-specific light-suitability functions. We tested the model against field observations from Xinglong Lake (Chengdu, China) under 5-year and 50-year design storms. Ecological risk exhibited a clear west-to-east gradient. Under the 5-year storm, high-risk cells (complete inhibition) formed a narrow band at the eastern inlet and overlapped 82% with the SSC > 0.1 kg m⁻³ plume at 6 h; several western macrophyte beds returned to “suitable” status by 72 h. In contrast, the 50-year event pushed R > 0.9 over all macrophyte beds, with slow recovery after 192 h. Lake-scale risk peaked above 80% within 24 h for both return periods, but residual risk remained elevated in the 50-year scenario owing to the larger spatial footprint. The study provides a transferable early-warning tool for lake managers to decide when to trigger low-cost interventions and species-specific resilience rankings to guide targeted vegetation protection in shallow urban lakes worldwide. Full article

(This article belongs to the Special Issue Sustainable Research on Water Quality Monitoring and Nutrient Pollution Control)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Water, Volume 17, Issue 19 (October-1 2025) – 45 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI