Water

14 pages, 1010 KiB

Open AccessArticle

Hydropower Microgeneration in Detention Basins: A Case Study of Santa Lúcia Basin in Brazil

by Azuri Sofia Gally Koroll, Rodrigo Perdigão Gomes Bezerra, André Ferreira Rodrigues, Bruno Melo Brentan, Joaquín Izquierdo and Gustavo Meirelles

Water 2025, 17(15), 2219; https://doi.org/10.3390/w17152219 - 24 Jul 2025

Abstract

Flood control infrastructure is essential for the development of cities and the population’s well-being. The goal is to protect human and economic resources by reducing the inundation area and controlling the flood level and peak discharges. Detention basins can do this by storing [...] Read more.

Flood control infrastructure is essential for the development of cities and the population’s well-being. The goal is to protect human and economic resources by reducing the inundation area and controlling the flood level and peak discharges. Detention basins can do this by storing a large volume of water to be released after the peak discharge. By doing this, a large amount of energy is stored, which can be recovered via micro-hydropower. In addition, as the release flow is controlled and almost constant, Pumps as Turbines (PAT) could be a feasible and economic option in these cases. Thus, this study investigates the feasibility of micro-hydropower (MHP) in urban detention basins, using the Santa Lúcia detention basin in Belo Horizonte as a case study. The methodology involved hydrological modeling, hydraulic analysis, and economic and environmental assessment. The results demonstrated that PAT selection has a crucial role in the feasibility of the MHP, and exploiting rainfall with lower intensities but higher frequencies is more attractive. Using multiple PATs with different operating points also showed promising results in improving energy production. In addition to the economic benefits, the MHP in the detention basin produces minimal environmental impact and, as it exploits a wasted energy source, it also reduces the carbon footprint in the urban water cycle. Full article

(This article belongs to the Special Issue Research Status of Operation and Management of Hydropower Station)

17 pages, 467 KiB

Open AccessArticle

Comparative Account of Tolerance of Different Submerged Macrophytes to Ammonia Nitrogen in the Water Column: Implications for Remediation and Ecological Rehabilitation of Nutrient-Enriched Aquatic Environments

by Shijiang Zhu, Tao Zhao, Shubiao Gui, Wen Xu, Kun Hao and Yun Zhong

Water 2025, 17(15), 2218; https://doi.org/10.3390/w17152218 - 24 Jul 2025

Abstract

This study aims to select the most suitable submerged plants for the remediation and ecological rehabilitation of nutrient-enriched aquatic environments. The experiment selected Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii as research objects. An artificial outdoor pot experiment was conducted with six different [...] Read more.

This study aims to select the most suitable submerged plants for the remediation and ecological rehabilitation of nutrient-enriched aquatic environments. The experiment selected Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii as research objects. An artificial outdoor pot experiment was conducted with six different levels of ammonia nitrogen: 2, 4, 6, 8, 12, and 16 mg/L. The present study measured the physiological and growth parameters of submerged macrophytes under varying ammonia nitrogen concentrations. The response characteristics of plants to ammonia nitrogen stress were analyzed, and the tolerance thresholds of different submerged macrophyte species to ammonia nitrogen were determined. This enabled us to screen for ammonia nitrogen-tolerant pioneer species suitable for water ecological restoration in eutrophic water bodies. The experiment spanned 28 days. The results showed that the maximum suitable concentration and maximum tolerance concentration of ammonia nitrogen for Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii were 2, 4, and 4 mg/L and 4, 12, and 8 mg/L. Submerged plants can grow normally within their maximum ammonia nitrogen tolerance concentration. When the concentration exceeds the maximum tolerance level, the growth of submerged plants is severely stressed by ammonia nitrogen. Low ammonia nitrogen concentrations promote the growth of submerged macrophyte biomass and chlorophyll content as well as the accumulation of dry matter in plants, while high ammonia nitrogen concentrations damage the antioxidant enzyme system and inhibit the growth of submerged plants. The tolerance of the three submerged macrophytes to ammonia nitrogen is as follows: Myriophyllum verticillatum > Elodea nuttallii > Vallisneria natans. Therefore, Myriophyllum verticillatum should be chosen as the ammonia nitrogen-tolerant pioneer species in the ecological restoration of eutrophic water bodies. The research results can provide a theoretical basis for the application of aquatic macrophytes in the treatment of eutrophic water bodies and ecological restoration. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

17 pages, 1066 KiB

Open AccessArticle

Comparative Study of the Microalgae-Based Wastewater Treatment, in an Oil Refining Industry Cogeneration Concept

by Ena Pritišanac, Maja Fafanđel, Ines Haberle, Sunčana Geček, Marinko Markić, Nenad Bolf, Jela Vukadin, Goranka Crnković, Tin Klanjšček, Luka Žilić and Maria Blažina

Water 2025, 17(15), 2217; https://doi.org/10.3390/w17152217 - 24 Jul 2025

Abstract

Microalage are broadly recognized as promising agents for sustainable wastewater treatment and biomass generation. However, industrial effluents such as petroleum refinery wastewater (WW) present challenges due to toxic growth inhibiting substances. Three marine microalgae species: Pseudochloris wilhelmii, Nannochloropsis gaditana and Synechococcus sp. [...] Read more.

Microalage are broadly recognized as promising agents for sustainable wastewater treatment and biomass generation. However, industrial effluents such as petroleum refinery wastewater (WW) present challenges due to toxic growth inhibiting substances. Three marine microalgae species: Pseudochloris wilhelmii, Nannochloropsis gaditana and Synechococcus sp. MK568070 were examined for cultivation potential in oil refinery WW. Their performance was evaluated in terms of growth dynamics, lipid productivity, and toxicity reduction, with a focus on their suitability for largescale industrial use. N. gaditana demonstrated the highest growth rate and lipid content (37% d.w.) as well as lipid productivity (29.45 mg/(Lday)) with the N-uptake rate of 0.698 mmol/(gday). The highest specific DIN uptake rate was observed inn P. wilhelmii (0.895 mmol/(gday) along with the highest volumetric productivity (93.9 mg/L/day) and WW toxicity removal (76.5%), while Synechococcus sp. MK568070 demonstrated lower performance metrics. A simple numerical model was applied to calculate continuous operation based on empirical results of batch experiments. Sustainability of the microalgae-based WW remediation under the conditions of optimized lipid biomass production was estimated, regarding 2019–2022–2025 cost dynamics. Parameters for optimum open raceway pond cultivation were calculated, and the biomass production accumulation was estimated, with the highest biomass production noted in P. wilhelmii (171.38 t/year). Comparison of treatment costs, production costs and revenue showed that the best candidate for WW remediation is N. gaditana. Full article

(This article belongs to the Special Issue Environmental Biotechnology Applied to Water and Wastewater Treatment Processes)

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22 pages, 4836 KiB

Open AccessArticle

Time-Variant Instantaneous Unit Hydrograph Based on Machine Learning Pretraining and Rainfall Spatiotemporal Patterns

by Wenyuan Dong, Guoli Wang, Guohua Liang and Bin He

Water 2025, 17(15), 2216; https://doi.org/10.3390/w17152216 - 24 Jul 2025

Abstract

The hydrological response of a watershed is strongly influenced by the spatiotemporal dynamics of rainfall. Rainfall events of similar magnitude can produce markedly different flood processes due to variations in the spatiotemporal patterns of rainfall, posing significant challenges for flood forecasting under complex [...] Read more.

The hydrological response of a watershed is strongly influenced by the spatiotemporal dynamics of rainfall. Rainfall events of similar magnitude can produce markedly different flood processes due to variations in the spatiotemporal patterns of rainfall, posing significant challenges for flood forecasting under complex rainfall scenarios. Traditional methods typically rely on high-resolution or synthetic rainfall data to characterize the scale, direction and velocity of rainstorms, in order to analyze their impact on the flood process. These studies have shown that storms traveling along the main river channel tend to exert the greatest impact on flood processes. Therefore, tracking the movement of the rainfall center along the flow direction, especially when only rain gauge data are available, can reduce model complexity while maintaining forecast accuracy and improving model applicability. This study proposes a machine learning-based time-variable instantaneous unit hydrograph that integrates rainfall spatiotemporal dynamics using quantitative spatial indicators. To overcome limitations of traditional variable unit hydrograph methods, a pre-training and fine-tuning strategy is employed to link the unit hydrograph S-curve with rainfall spatial distribution. First, synthetic pre-training data were used to enable the machine learning model to learn the shape of the S-curve and its general pattern of variation with rainfall spatial distribution. Then, real flood data were employed to learn the actual runoff routing characteristics of the study area. The improved model allows the unit hydrograph to adapt dynamically to rainfall evolution during the flood event, effectively capturing hydrological responses under varying spatiotemporal patterns. The case study shows that the improved model exhibits superior performance across all runoff routing metrics under spatiotemporal rainfall variability. The improved model increased the simulation qualified rate for historical flood events, with significant rainfall center movement during the event from 63% to 90%. This study deepens the understanding of how rainfall dynamics influence watershed response and enhances hourly-scale flood forecasting, providing support for disaster early warning with strong theoretical and practical significance. Full article

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20 pages, 1587 KiB

Open AccessArticle

Sustainability Synergies Between Water Governance and Agrotourism Development in the Semi-Arid Climate: A Case Study of Esmeraldas Province, Ecuador

by Eliana Ivanova Cuero Espinoza, Qudus Adeyi, Mirza Junaid Ahmad, Hwa-Seok Hwang and Kyung-Sook Choi

Water 2025, 17(15), 2215; https://doi.org/10.3390/w17152215 - 24 Jul 2025

Abstract

Effective water governance is essential for sustainable development amidst water scarcity challenges in semi-arid regions like Esmeraldas Province, which has substantial agrotourism potential. Yet, fragmented governance and chronic water shortages threaten its viability. Using a mixed-method approach, this study analyzed how sustainable water [...] Read more.

Effective water governance is essential for sustainable development amidst water scarcity challenges in semi-arid regions like Esmeraldas Province, which has substantial agrotourism potential. Yet, fragmented governance and chronic water shortages threaten its viability. Using a mixed-method approach, this study analyzed how sustainable water governance can support agrotourism development in Esmeraldas Province, Ecuador. This study combined policy gaps analysis, stakeholder surveys (policymakers, farmers, community leaders, and tourism operators), and water availability using the Standardized Precipitation Evapotranspiration Index (SPEI) from 1980 to 2022. The results revealed a lack of policy regulation and water infrastructure as the major governance gaps that need more intervention. The survey respondents indicated that water is mainly used for domestic and economic activities and the conservation of natural ecosystems. The SPEI revealed a significant drought trend falling below −3, with severe drought years coinciding with many crop losses and a fall in tourism. This study highlights the interconnection between water governance and agrotourism in Esmeraldas, Ecuador, proposing a strategic framework that incorporates adaptive governance principles and inclusive participation mechanisms, emphasizing targeted capacity building to strengthen water management practices and enhance the Sustainable Development Goals for agrotourism resilience. Full article

(This article belongs to the Special Issue Water: Economic, Social and Environmental Analysis)

19 pages, 7033 KiB

Open AccessArticle

The Influence of Combined Energy Dissipators on Navigable Flow Characteristics at Main Channel—Tributary Confluences in Trans-Basin Canals: A Case Study of the Jiuzhou River Section, Pinglu Canal

by Linfeng Han, Kaixian Deng, Tao Yu and Junhui He

Water 2025, 17(15), 2214; https://doi.org/10.3390/w17152214 - 24 Jul 2025

Abstract

The flow characteristics at the tributary entrance are crucial for ensuring safe navigation where the main channel and tributary converge. Along the inter-basin canal, numerous tributaries feature large confluence angles and significant flow discharge ratios. An experimental study investigated how these factors influence [...] Read more.

The flow characteristics at the tributary entrance are crucial for ensuring safe navigation where the main channel and tributary converge. Along the inter-basin canal, numerous tributaries feature large confluence angles and significant flow discharge ratios. An experimental study investigated how these factors influence flow patterns, leading to proposed mitigation measures. This research employed a 1:50-scale physical river model and a sediment deposition model. It analyzed navigable flow conditions including velocity, flow patterns, the confluence ratio, the bottom elevation difference, and the confluence angle at the main channel–tributary junction. Focusing on the Jiuzhou River tributary entrance (Pinglu Canal), which has a large confluence ratio, significant bottom elevation difference, and wide confluence angle, this study tested two solutions: a single energy dissipator and a combined energy dissipator system. Sediment deposition modeling compared the effectiveness of these approaches. The results showed that implementing a steep slope with a three-stage stilling pool in the Jiuzhou River entrance section effectively manages confluences with large elevation differences, wide angles, and high flow discharge ratios. This configuration significantly improves entrance flow characteristics. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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29 pages, 6950 KiB

Open AccessArticle

At-Site Versus Regional Frequency Analysis of Sub-Hourly Rainfall for Urban Hydrology Applications During Recent Extreme Events

by Sunghun Kim, Kyungmin Sung, Ju-Young Shin and Jun-Haeng Heo

Water 2025, 17(15), 2213; https://doi.org/10.3390/w17152213 - 24 Jul 2025

Abstract

Accurate rainfall quantile estimation is critical for urban flood management, particularly given the escalating climate change impacts. This study comprehensively compared at-site frequency analysis and regional frequency analysis for sub-hourly rainfall quantile estimation, using data from 27 sites across Seoul. The analysis focused [...] Read more.

Accurate rainfall quantile estimation is critical for urban flood management, particularly given the escalating climate change impacts. This study comprehensively compared at-site frequency analysis and regional frequency analysis for sub-hourly rainfall quantile estimation, using data from 27 sites across Seoul. The analysis focused on Seoul’s disaster prevention framework (30-year and 100-year return periods). Employing L-moment statistics and Monte Carlo simulations, the rainfall quantiles were estimated, the methodological performance was evaluated, and Seoul’s current disaster prevention standards were assessed. The analysis revealed significant spatio-temporal variability in Seoul’s precipitation, causing considerable uncertainty in individual site estimates. A performance evaluation, including the relative root mean square error and confidence interval, consistently showed regional frequency analysis superiority over at-site frequency analysis. While at-site frequency analysis demonstrated better performance only for short return periods (e.g., 2 years), regional frequency analysis exhibited a substantially lower relative root mean square error and significantly narrower confidence intervals for larger return periods (e.g., 10, 30, 100 years). This methodology reduced the average 95% confidence interval width by a factor of approximately 2.7 (26.98 mm versus 73.99 mm). This enhanced reliability stems from the information-pooling capabilities of regional frequency analysis, mitigating uncertainties due to limited record lengths and localized variabilities. Critically, regionally derived 100-year rainfall estimates consistently exceeded Seoul’s 100 mm disaster prevention threshold across most areas, suggesting that the current infrastructure may be substantially under-designed. The use of minute-scale data underscored its necessity for urban hydrological modeling, highlighting the inadequacy of conventional daily rainfall analyses. Full article

(This article belongs to the Special Issue Urban Flood Frequency Analysis and Risk Assessment)

21 pages, 2134 KiB

Open AccessArticle

From Silos to Synergy: Improving Coordination in Local Flood Management

by Wibke de Boer, Lucas Flath, Michèle Knodt and Britta Schmalz

Water 2025, 17(15), 2212; https://doi.org/10.3390/w17152212 - 24 Jul 2025

Abstract

Flood risk governance has gained increasing attention as climate change and urbanization amplify flood risks. While much of the literature has focused on national and supranational governance frameworks, sectoral integration, and public participation, there remains a critical gap in understanding horizontal coordination within [...] Read more.

Flood risk governance has gained increasing attention as climate change and urbanization amplify flood risks. While much of the literature has focused on national and supranational governance frameworks, sectoral integration, and public participation, there remains a critical gap in understanding horizontal coordination within municipal administrations—particularly in medium-sized cities. This study examines how local governments coordinate flood risk management across different departments and administrative units, identifying key challenges and enabling factors. Using a case study of Mörfelden-Walldorf, a medium-sized city in southern Hesse, Germany, we analyze the internal governance dynamics shaping flood resilience. The research highlights institutional fragmentation, sectoral silos, and resource constraints as key barriers to effective coordination while also identifying mechanisms that facilitate cross-departmental collaboration. By integrating insights from the public administration literature with flood governance scholarship, this study contributes to a more nuanced understanding of local-level flood risk governance. The findings provide practical implications for enhancing municipal flood resilience through improved governance structures and coordination mechanisms. Full article

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

25 pages, 1394 KiB

Open AccessArticle

Peculiarities of ²²²Radon and ²³⁸Uranium Behavior in Mineral Waters of Highland Terrains

by George Chelnokov, Vasilii Lavrushin, Natalya Kharitonova, Andrey Pavlov and Farid Salikhov

Water 2025, 17(15), 2211; https://doi.org/10.3390/w17152211 - 24 Jul 2025

Abstract

Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for ²²²Rn activity and ²³⁸U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to [...] Read more.

Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for ²²²Rn activity and ²³⁸U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to assess the potential health risk associated with ²³⁸U and ²²²Rn. It was found that in mineral waters of the Pamir, the concentrations of ²³⁸U (0.004–13.3 µg/L) and activity of ²²²Rn (8–130 Bq/L) are higher than in the Elbrus area: 0.04–3.74 µg/L and 6–33 Bq/L, respectively. Results indicate that uranium mobility in water is strongly influenced by T, pH, and Eh, but is less affected by the age of host rocks or springs' elevation, whereas radon activity in waters depends on the age of rocks, spring elevation, ²³⁸U content, and values of δ¹⁸O and δ²H in water. This study reveals fundamental geological distinctions governing uranium and radon sources in the mineral waters of these regions. Isotopic evidence (²²²Rn and ³He/⁴He) demonstrates crustal radon sources prevail in Pamir, whereas the Elbrus system suggests mantle-derived components. The U concentrations do not exceed 30 µg/L, and most water samples (94%) showed ²²²Rn activities below 100 Bq/L, complying with the drinking water exposure limits recommended by the World Health Organization and European Union Directive. However, in intermountain depressions of the Pamirs, at low absolute elevations (~2300 m), radon concentrations in water can increase significantly, which requires special attention and study. Full article

17 pages, 1171 KiB

Open AccessArticle

ABAQUS-Based Numerical Analysis of Land Subsidence Induced by Pit Pumping in Multi-Aquifer Systems

by Jiao Chen, Chaofeng Zeng, Xiuli Xue, Shuo Wang, Youwu Zhao and Zirui Zhang

Water 2025, 17(15), 2210; https://doi.org/10.3390/w17152210 - 24 Jul 2025

Abstract

Foundation pit pumping induces groundwater drawdown both inside and outside the pit, consequently causing surrounding land subsidence. Based on actual engineering cases, this study established a three-dimensional numerical model using ABAQUS software (version 6.14-4) to systematically investigate the temporal evolution of groundwater drawdown [...] Read more.

Foundation pit pumping induces groundwater drawdown both inside and outside the pit, consequently causing surrounding land subsidence. Based on actual engineering cases, this study established a three-dimensional numerical model using ABAQUS software (version 6.14-4) to systematically investigate the temporal evolution of groundwater drawdown and land subsidence during pit pumping, while quantifying the relationship between drawdown and subsidence stabilization time under different parameters. The key findings are as follows: (1) land subsidence stabilization time (50 days) is governed by external phreatic layer response, reaching 2.3 times longer than isolated aquifer conditions (22 days); (2) medium-permeability strata (0.01–10 K_0,Ad_Ⅱ) showed peak sensitivity to drawdown–subsidence coupling; (3) pumping from a confined aquifer extends the subsidence stabilization time by a factor of 1.1 compared to phreatic aquifer conditions. These findings provide valuable insights for the design and risk assessment of dewatering strategies in foundation pits within multi-aquifer systems. Full article

(This article belongs to the Special Issue Advances in Water Related Geotechnical Engineering)

20 pages, 4961 KiB

Open AccessArticle

Modelling of Water Level Fluctuations and Sediment Fluxes in Nokoué Lake (Southern Benin)

by Tètchodiwèï Julie-Billard Yonouwinhi, Jérôme Thiébot, Sylvain S. Guillou, Gérard Alfred Franck Assiom d’Almeida and Felix Kofi Abagale

Water 2025, 17(15), 2209; https://doi.org/10.3390/w17152209 - 24 Jul 2025

Abstract

Nokoué Lake is located in the south of Benin and is fed by the Ouémé and Sô Rivers. Its hydrosedimentary dynamics were modelled using Telemac2D, incorporating the main environmental factors of this complex ecosystem. The simulations accounted for flow rates and suspended solids [...] Read more.

Nokoué Lake is located in the south of Benin and is fed by the Ouémé and Sô Rivers. Its hydrosedimentary dynamics were modelled using Telemac2D, incorporating the main environmental factors of this complex ecosystem. The simulations accounted for flow rates and suspended solids concentrations during periods of high and low water. The main factors controlling sediment transport were identified. The model was validated using field measurements of water levels and suspended solids. The results show that the north–south current velocity ranges from 0.5 to 1 m/s during periods of high water and 0.1 to 0.5 m/s during low-water periods. Residual currents are influenced by rainfall, river discharge, and tides. Complex circulation patterns are caused by increased river flow during high water, while tides dominate during low water and transitional periods. The northern, western, and south-eastern parts of the lake have weak residual currents and are, therefore, deposition zones for fine sediments. The estimated average annual suspended solids load for 2022–2023 is 17 Mt. The model performance shows a strong agreement between the observed and simulated values: R² = 0.91 and NSE = 0.93 for water levels and R² = 0.86 and NSE = 0.78 for sediment transport. Full article

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18 pages, 1137 KiB

Open AccessArticle

Exploring Social Water Research: Quantitative Network Analysis as Assistance for Qualitative Social Research

by Magdalena Riedl and Peter Schulz

Water 2025, 17(15), 2208; https://doi.org/10.3390/w17152208 - 24 Jul 2025

Abstract

This paper presents a meta-analysis of social research on water, offering a novel methodological contribution to the study of emerging interdisciplinary research fields. We propose and implement a mixed methods framework that integrates quantitative network analysis with qualitative research, aiming to enhance both [...] Read more.

This paper presents a meta-analysis of social research on water, offering a novel methodological contribution to the study of emerging interdisciplinary research fields. We propose and implement a mixed methods framework that integrates quantitative network analysis with qualitative research, aiming to enhance both to give access to new emerging empirical fields and enhance the analytical depth of empirical social research. Drawing on a dataset of publications from the Web of Science over four distinct time intervals, we identify thematic clusters through keyword co-occurrence networks that reveal the evolving structure and internal dynamics of the field. Our findings show a clear trend toward increasing interdisciplinarity, responsiveness to global events, and contemporary challenges such as the emergence of COVID-19 and the continued centrality of topics related to water management and evaluation. By uncovering latent structures, our approach not only maps the field’s development but also lays the foundation for targeted qualitative analysis of articles representative of identified clusters. This methodological design contributes to the broader discourse on mixed methods research in the social sciences by demonstrating how computational tools can enhance the transparency and reliability of qualitative inquiry without sacrificing its interpretive richness. Furthermore, this study opens new avenues for critically reflecting on the epistemic culture of social water research, particularly in relation to its proximity to applied science and governance-oriented perspectives. The proposed method holds potential relevance for both academic researchers and decision makers in the water sector, offering a means to systematically access dispersed knowledge and identify underrepresented subfields. Overall, the study showcases the potential of mixed methods designs for navigating and structuring complex interdisciplinary research landscapes. Full article

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18 pages, 15284 KiB

Open AccessArticle

Two-Dimensional Flood Modeling of a Piping-Induced Dam Failure Triggered by Seismic Deformation: A Case Study of the Doğantepe Dam

by Fatma Demir, Suleyman Sarayli, Osman Sonmez, Melisa Ergun, Abdulkadir Baycan and Gamze Tuncer Evcil

Water 2025, 17(15), 2207; https://doi.org/10.3390/w17152207 - 24 Jul 2025

Abstract

This study presents a scenario-based, two-dimensional flood modeling approach to assess the potential downstream impacts of a piping-induced dam failure triggered by seismic activity. The case study focuses on the Doğantepe Dam in northwestern Türkiye, located near an active branch of the North [...] Read more.

This study presents a scenario-based, two-dimensional flood modeling approach to assess the potential downstream impacts of a piping-induced dam failure triggered by seismic activity. The case study focuses on the Doğantepe Dam in northwestern Türkiye, located near an active branch of the North Anatolian Fault. Critical deformation zones were previously identified through PLAXIS 2D seismic analyses, which served as the physical basis for a dam break scenario. This scenario was modeled using the HEC-RAS 2D platform, incorporating high-resolution topographic data, reservoir capacity, and spatially varying Manning’s roughness coefficients. The simulation results show that the flood wave reaches downstream settlements within the first 30 min, with water depths exceeding 3.0 m in low-lying areas and flow velocities surpassing 6.0 m/s, reaching up to 7.0 m/s in narrow sections. Inundation extents and hydraulic parameters such as water depth and duration were spatially mapped to assess flood hazards. The study demonstrates that integrating physically based seismic deformation data with hydrodynamic modeling provides a realistic and applicable framework for evaluating flood risks and informing emergency response planning. Full article

(This article belongs to the Special Issue Disaster Analysis and Prevention of Dam and Slope Engineering)

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1 pages, 120 KiB

Open AccessCorrection

Correction: Mostafa et al. Groundwater Potential Mapping in Semi-Arid Areas Using Integrated Remote Sensing, GIS, and Geostatistics Techniques. Water 2025, 17, 1909

by Ahmed El-sayed Mostafa, Mahrous A. M. Ali, Faissal A. Ali, Ragab Rabeiy, Hussein A. Saleem, Mosaad Ali Hussein Ali and Ali Shebl

Water 2025, 17(15), 2206; https://doi.org/10.3390/w17152206 - 24 Jul 2025

Abstract

In the original publication [...] Full article

16 pages, 2159 KiB

Open AccessArticle

A New Depth-Averaged Eulerian SPH Model for Passive Pollutant Transport in Open Channel Flows

by Kao-Hua Chang, Kai-Hsin Shih and Yung-Chieh Wang

Water 2025, 17(15), 2205; https://doi.org/10.3390/w17152205 - 24 Jul 2025

Abstract

Various nature-based solutions (NbS)—such as constructed wetlands, drainage ditches, and vegetated buffer strips—have recently demonstrated strong potential for mitigating pollutant transport in open channels and river systems. Numerical modeling is a widely adopted and effective approach for assessing the performance of these interventions. [...] Read more.

Various nature-based solutions (NbS)—such as constructed wetlands, drainage ditches, and vegetated buffer strips—have recently demonstrated strong potential for mitigating pollutant transport in open channels and river systems. Numerical modeling is a widely adopted and effective approach for assessing the performance of these interventions. This study presents the first development of a two-dimensional (2D) meshless advection–diffusion model based on an Eulerian smoothed particle hydrodynamics (SPH) framework, specifically designed to simulate passive pollutant transport in open channel flows. The proposed model marks a pioneering application of the ESPH technique to environmental pollutant transport problems. It couples the 2D depth-averaged shallow water equations with an advection–diffusion equation to represent both fluid motion and pollutant concentration dynamics. A uniform particle arrangement ensures that each fluid particle interacts symmetrically with eight neighboring particles for flux computation. To represent the pollutant transport process, the dispersion coefficient is defined as the sum of molecular and turbulent diffusion components. The turbulent diffusion coefficient is calculated using a prescribed turbulent Schmidt number and the eddy viscosity obtained from a Smagorinsky-type mixing-length turbulence model. Three analytical case studies, including one-dimensional transcritical open channel flow, 2D isotropic and anisotropic diffusion in still water, and advection–diffusion in a 2D uniform flow, are employed to verify the model’s accuracy and convergence. The model demonstrates first-order convergence, with relative root mean square errors (RRMSEs) of approximately 0.2% for water depth and velocity, and 0.1–0.5% for concentration. Additionally, the model is applied to a laboratory experiment involving 2D pollutant dispersion in a 90° junction channel. The simulated results show good agreement with measured velocity and concentration distributions. These findings indicate that the developed model is a reliable and effective tool for evaluating the performance of NbS in mitigating pollutant transport in open channels and river systems. Full article

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

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19 pages, 5495 KiB

Open AccessArticle

Application of Empirical Mode Decomposition to Land Surface Temperature Projection Under a Changing Climate

by Che-Wei Chang and Wen-Cheng Huang

Water 2025, 17(15), 2204; https://doi.org/10.3390/w17152204 - 23 Jul 2025

Abstract

This study takes the daily temperature series of Taipei City as an example and proposes a data projection method based on Empirical Mode Decomposition (EMD), which effectively resolves the challenge of modeling non-stationary sequences. According to the daily mean temperature records from 1971 [...] Read more.

This study takes the daily temperature series of Taipei City as an example and proposes a data projection method based on Empirical Mode Decomposition (EMD), which effectively resolves the challenge of modeling non-stationary sequences. According to the daily mean temperature records from 1971 to 2023, Taipei has experienced an average warming rate of 0.02 °C per year. After applying EMD, the data were decomposed into 12 intrinsic mode functions (IMFs) and one residual trend. Among them, IMF5, with a period of 352 days (approximately one year), contributes 78% of the total energy, representing the dominant climatic cycle component. In this study, daily temperatures were categorized into five thermal levels: Cold (<12 °C), Cool (12–18 °C), Moderate (18–27 °C), Warm (27–32 °C), and Hot (>32 °C). In addition, using a 5-year moving process based on the annual EMD results, the IMFs and residuals were recombined to generate 390,625 synthetic sequences per year. Results show that the monthly mean temperatures of each year’s simulations closely match the observations, capturing the non-stationary characteristics of temperature variations. The overall classification accuracy of simulated versus observed daily temperature categories ranges from 60% to 71%, with an average of 65.1%. In summary, the EMD combined with the 5-year moving process developed in this study demonstrates a helpful data projection approach with effective reconstruction of periodic structures and stable simulation accuracy. It offers practical value for reconstructing urban climate variability, conducting risk assessments, and analyzing long-term warming trends. Moreover, it serves as a vital tool for modeling non-stationary climate data and supporting future projections. Full article

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

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18 pages, 4162 KiB

Open AccessArticle

Evaluation of Wake Structure Induced by Helical Hydrokinetic Turbine

by Erkan Alkan, Mehmet Ishak Yuce and Gökmen Öztürkmen

Water 2025, 17(15), 2203; https://doi.org/10.3390/w17152203 - 23 Jul 2025

Abstract

This study investigates the downstream wake characteristics of a helical hydrokinetic turbine through combined experimental and numerical analyses. A four-bladed helical turbine with a 20 cm rotor diameter and blockage ratio of 53.57% was tested in an open water channel under a flow [...] Read more.

This study investigates the downstream wake characteristics of a helical hydrokinetic turbine through combined experimental and numerical analyses. A four-bladed helical turbine with a 20 cm rotor diameter and blockage ratio of 53.57% was tested in an open water channel under a flow rate of 180 m³/h, corresponding to a Reynolds number of approximately 90 × 10³. Velocity measurements were collected at 13 downstream cross-sections using an Acoustic Doppler Velocimeter, with each point sampled repeatedly. Standard error analysis was applied to quantify measurement uncertainty. Complementary numerical simulations were conducted in ANSYS Fluent using a steady-state k-ω Shear Stress Transport (SST) turbulence model, with a mesh of 4.7 million elements and mesh independence confirmed. Velocity deficit and turbulence intensity were employed as primary parameters to characterize the wake structure, while the analysis also focused on the recovery of cross-sectional velocity profiles to validate the extent of wake influence. Experimental results revealed a maximum velocity deficit of over 40% in the near-wake region, which gradually decreased with downstream distance, while turbulence intensity exceeded 50% near the rotor and dropped below 10% beyond 4 m. In comparison, numerical findings showed a similar trend but with lower peak velocity deficits of 16.6%. The root mean square error (RMSE) and mean absolute error (MAE) between experimental and numerical mean velocity profiles were calculated as 0.04486 and 0.03241, respectively, demonstrating reasonable agreement between the datasets. Extended simulations up to 30 m indicated that flow profiles began to resemble ambient conditions around 18–20 m. The findings highlight the importance of accurately identifying the downstream distance at which the wake effect fully dissipates, as this is crucial for determining appropriate inter-turbine spacing. The study also discusses potential sources of discrepancies between experimental and numerical results, as well as the limitations of the modeling approach. Full article

(This article belongs to the Special Issue Optimization-Simulation Modeling of Sustainable Water Resource)

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28 pages, 48299 KiB

Open AccessArticle

An Extensive Italian Database of River Embankment Breaches and Damages

by Michela Marchi, Ilaria Bertolini, Laura Tonni, Luca Morreale, Andrea Colombo, Tommaso Simonelli and Guido Gottardi

Water 2025, 17(15), 2202; https://doi.org/10.3390/w17152202 - 23 Jul 2025

Abstract

River embankments are critical flood defense structures, stretching for thousands of kilometers across alluvial plains. They often originated as natural levees resulting from overbank flows and were later enlarged using locally available soils yet rarely designed according to modern engineering standards. Substantially under-characterized, [...] Read more.

River embankments are critical flood defense structures, stretching for thousands of kilometers across alluvial plains. They often originated as natural levees resulting from overbank flows and were later enlarged using locally available soils yet rarely designed according to modern engineering standards. Substantially under-characterized, their performance to extreme events provides an invaluable opportunity to highlight their vulnerability and then to improve monitoring, management, and reinforcement strategies. In May 2023, two extreme meteorological events hit the Emilia-Romagna region in rapid succession, causing numerous breaches along river embankments and therefore widespread flooding of cities and territories. These were followed by two additional intense events in September and October 2024, marking an unprecedented frequency of extreme precipitation episodes in the history of the region. This study presents the methodology adopted to create a regional database of 66 major breaches and damages that occurred during May 2023 extensive floods. The database integrates multi-source information, including field surveys; remote sensing data; and eyewitness documentation collected before, during, and after the events. Preliminary interpretation enabled the identification of the most likely failure mechanisms—primarily external erosion, internal erosion, and slope instability—often acting in combination. The database, unprecedented in Italy and with few parallels worldwide, also supported a statistical analysis of breach widths in relation to failure mechanisms, crucial for improving flood hazard models, which often rely on generalized assumptions about breach development. By offering insights into the real-scale behavior of a regional river defense system, the dataset provides an important tool to support river embankments risk assessment and future resilience strategies. Full article

(This article belongs to the Special Issue Recent Advances in Flood Risk Assessment and Management)

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16 pages, 4204 KiB

Open AccessArticle

Assessment of the Source and Dynamics of Water Inrush Based on Hydrochemical Mixing Model in Zhaxikang Mining Area, Tibet, China

by Hongyu Gu, Yujie Liu, Huizhong Liu, Xinyu Cen, Jinxian Zhong, Dewei Wang and Lei Yi

Water 2025, 17(15), 2201; https://doi.org/10.3390/w17152201 - 23 Jul 2025

Abstract

Water source identification and dynamic assessment are critical for mining safety, particularly in mines governed by complex geological structures. The hydrochemical mixing model demonstrates a natural advantage for early warning of water intrusion compared to geophysical monitoring techniques. This study discusses core issues [...] Read more.

Water source identification and dynamic assessment are critical for mining safety, particularly in mines governed by complex geological structures. The hydrochemical mixing model demonstrates a natural advantage for early warning of water intrusion compared to geophysical monitoring techniques. This study discusses core issues related to the mixing model, including the conceptual framework, selection of end-members, and choice of tracers, and formulates principles for general applicability. In this study, three sources were identified using the conceptual model and hydrochemical analysis: water in F7 (main fault), shallow fracture water, and river water. A correlation analysis and variability analysis were applied to determine the tracers, and the ¹⁸O, D, Cl, B, and Li were determined. The end-members of the three sources are time-dependent in July and September, especially the shallow fracture water’s end-members. The dynamics of the mixing ratios of the three sources suggest that river water contributes only to the inrush (1–4%), with this being especially low in September, as the increasing hydraulic gradient from south to north prevents recharge. The water in F7 accounts for at least 70% of the inrush water. Shallow fracture water accounts for the rest and increases slightly in September as the precipitation increases in mining-disturbed areas. Finally, this work makes the later water control work more targeted. Full article

(This article belongs to the Section Hydrogeology)

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15 pages, 1787 KiB

Open AccessArticle

Flow Regime Impacts on Chemical Pollution in the Water and Sediments of the Moopetsi River and Human Health Risk in South Africa

by Abraham Addo-Bediako, Thato Matita and Wilmien Luus-Powell

Water 2025, 17(15), 2200; https://doi.org/10.3390/w17152200 - 23 Jul 2025

Abstract

Many effluents from human activities discharged into freshwater ecosystems cause chemical pollution. Chemical pollution in rivers is a serious threat to freshwater ecosystems due to the associated potential human health risks. This study determined the extent of chemical pollution, identified potential sources of [...] Read more.

Many effluents from human activities discharged into freshwater ecosystems cause chemical pollution. Chemical pollution in rivers is a serious threat to freshwater ecosystems due to the associated potential human health risks. This study determined the extent of chemical pollution, identified potential sources of pollution and assessed human health risk in the Moopetsi River, an intermittent river in the Limpopo Province of South Africa. Chemical analyses were conducted on water and sediment samples collected during high-flow, low-flow and intermittent-flow regimes. The findings showed seasonal variations in the chemical pollution levels in the sediments and the highest contamination was measured during intermittent flow. The enrichment factor and geoaccumulation index values identified chromium and nickel as major contributors to sediment contamination. The mean arsenic, chromium and nickel levels exceeded the established guideline values. An evaluation of human health risk was conducted using ingestion and dermal absorption pathways. The results showed that ingestion has greater non-carcinogenic and carcinogenic risks than dermal exposure, especially for children during intermittent flow. The elements of great concern for non-carcinogenic risk were chromium, manganese and nickel and for carcinogenic risk, they were arsenic, chromium, nickel and lead. The outcome of this study is useful for waste management and conservation to reduce environmental degradation and human health risk. Full article

(This article belongs to the Special Issue Advances in Metal Removal and Recovery from Water)

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35 pages, 3950 KiB

Open AccessArticle

Macrozoobenthos Response to Sediment Contamination near the S/s Stuttgart Wreck: A Biological and Chemical Assessment in the Gulf of Gdańsk, Southern Baltic Sea

by Anna Tarała, Diana Dziaduch, Katarzyna Galer-Tatarowicz, Aleksandra Bojke, Maria Kubacka and Marcin Kalarus

Water 2025, 17(15), 2199; https://doi.org/10.3390/w17152199 - 23 Jul 2025

Abstract

This study provides an up-to-date assessment of the environmental status in the area of the S/s Stuttgart wreck in the southern Baltic Sea, focusing on macrozoobenthos, sediment chemistry, and contamination in Mytilus trossulus soft tissues. Comparative analyses from 2016 and 2023 revealed increased [...] Read more.

This study provides an up-to-date assessment of the environmental status in the area of the S/s Stuttgart wreck in the southern Baltic Sea, focusing on macrozoobenthos, sediment chemistry, and contamination in Mytilus trossulus soft tissues. Comparative analyses from 2016 and 2023 revealed increased species richness and distinct benthic assemblages, shaped primarily by depth and distance from the wreck. Among macrozoobenthos, there dominated opportunistic species, characterized by a high degree of resistance to the unfavorable state of the environment, suggesting adaptation to local conditions. Elevated concentrations of heavy metals were detected in sediments, with maximum values of Cd—0.85 mg·kg⁻¹, Cu—34 mg·kg⁻¹, Zn—119 mg·kg⁻¹, and Ni—32.3 mg·kg⁻¹. However, no significant correlations between sediment contamination and macrozoobenthos composition were found. In Mytilus trossulus, contaminant levels were mostly within regulatory limits; however, mercury concentrations reached 0.069 mg·kg⁻¹ wet weight near the wreck and 0.493 mg·kg⁻¹ at the reference station, both exceeding the threshold defined in national legislation (0.02 mg·kg⁻¹) (Journal of Laws of 2021, item 568). Condition indices for Macoma balthica were lower in the wreck area, suggesting sublethal stress. Ecotoxicological tests showed no acute toxicity in most sediment samples, emphasizing the complexity of pollutant effects. The data presented here not only enrich the existing literature on marine pollution but also contribute to the development of more effective environmental protection strategies for marine ecosystems under international protection. Full article

(This article belongs to the Special Issue Emerging Contaminants in Natural and Engineered Water Environments: Environmental Behavior, Ecological Effects and Control Strategies, 2nd Edition)

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14 pages, 4489 KiB

Open AccessArticle

Modifying Design Standards: The 2023 Extreme Flood’s Impact on Design Discharges in Slovenia

by Mojca Šraj and Nejc Bezak

Water 2025, 17(15), 2198; https://doi.org/10.3390/w17152198 - 23 Jul 2025

Abstract

An extreme flood event occurred in Slovenia in August 2023. This study evaluated the influence of this extreme flood on the design discharges in Slovenia. This evaluation was based on flood frequency analysis for the data from 33 gauging stations. Analyses were conducted [...] Read more.

An extreme flood event occurred in Slovenia in August 2023. This study evaluated the influence of this extreme flood on the design discharges in Slovenia. This evaluation was based on flood frequency analysis for the data from 33 gauging stations. Analyses were conducted with and without the 2023 peak discharge, i.e., for the periods 1961–2022 and 1961–2023, using eight different theoretical distribution functions. In addition, specific discharge values for the 2023 flood event were analyzed and compared with regional envelope curves for Europe. The findings of the study indicate that the impact of a single flood event on the design discharge values can be substantial. Moreover, an analysis of the specific discharges resulting from the 2023 flood event in Slovenia reveals that the values for all gauging stations considered are below the regional envelopes. Concurrently, the analysis indicates that a flood event larger than the 2023 event may occur in the future. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: The Impact of Climate Change on Water Resources)

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20 pages, 2336 KiB

Open AccessArticle

Microbial DNA-Based Monitoring of Underground Crude Oil Storage Bases Using Water-Sealed Rock-Cavern Tanks

by Ayae Goto, Shunichi Watanabe, Katsumasa Uruma, Yuki Momoi, Takuji Oomukai and Hajime Kobayashi

Water 2025, 17(15), 2197; https://doi.org/10.3390/w17152197 - 23 Jul 2025

Abstract

Strategic petroleum reserves are critical for energy security. In Japan, 0.5 million kiloliters of crude oil (12% of the state-owned reserves) is stored using underground rock-cavern tanks, which comprise unlined horizontal tunnels bored into bedrock. Crude oil is held within the tank by [...] Read more.

Strategic petroleum reserves are critical for energy security. In Japan, 0.5 million kiloliters of crude oil (12% of the state-owned reserves) is stored using underground rock-cavern tanks, which comprise unlined horizontal tunnels bored into bedrock. Crude oil is held within the tank by water inside the tank, the pressure of which is kept higher than that of the crude oil by natural groundwater and irrigation water. This study applied microbial DNA-based monitoring to assess the water environments in and around national petroleum-stockpiling bases (the Kuji, Kikuma, and Kushikino bases) using the rock-cavern tanks. Forty-five water samples were collected from the rock-cavern tanks, water-supply tunnels, and observation wells. Principal-component analysis and hierarchical clustering indicated that microbial profiles of the water samples reflect the local environments of their origins. Particularly, the microbial profiles of water inside the rock-cavern tanks were distinct from other samples, revealing biological conditions and hence environmental characteristics within the tanks. Moreover, the clustering analysis indicated distinct features of water samples that have not been detected by other monitoring methods. Thus, microbial DNA-based monitoring provides valuable information on the in situ environments of rock-cavern tanks and can serve as an extremely sensitive measurement to monitor the underground oil storage. Full article

(This article belongs to the Section Hydrogeology)

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15 pages, 2209 KiB

Open AccessArticle

Exploration of Phosphorus Release Characteristics in Sediments from the Plains River Network: Vertical Distribution and the Response of Phosphorus and Microorganisms

by Xiaoshuang Dong, Haojie Chen, Yongsheng Chang, Xixi Yang, Haoran Yang and Wei Huang

Water 2025, 17(15), 2196; https://doi.org/10.3390/w17152196 - 23 Jul 2025

Abstract

Plains River networks are important natural ecosystems that play a vital role in storing, draining, conserving, and purifying water. This study selected the river network in the northern plain of Jiaxing as the research area. Samples were collected in October 2023. Sediments were [...] Read more.

Plains River networks are important natural ecosystems that play a vital role in storing, draining, conserving, and purifying water. This study selected the river network in the northern plain of Jiaxing as the research area. Samples were collected in October 2023. Sediments were collected using a sampler and divided into five layers according to the collection depth, namely the surface layer (5 cm), the second layer (15 cm), the third layer (25 cm), the fourth layer (35 cm), and the bottom layer (45 cm). This study analyzed the vertical distribution of each form of phosphorus, the vertical distribution of the microbial community, and the response between the two in the sediments of this plain river network. The results showed high sediment TP concentrations (633.9–2534.7 mg/kg) in this plain river network. The vertical distribution trend of Fe-P was almost the same as that of TP and had the highest concentration (134.9–1860.1 mg/kg). Ca-P is the second highest phosphorus content, which is also an inert phosphorus component, as well as Al-P, and both exhibit a relatively low percentage of surface layers. Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria showed heterogeneity in the vertical distribution of sediments. The river network sediments in the Plains River have a high potential for phosphorus release, with most sites acting as phosphorus “sources”. The sediments in the second of these layers show a strong tendency to release phosphorus. Bottom sediments have a low capacity to both adsorb and release phosphorus. The findings of this study will provide a theoretical foundation for the prevention and management of river networks in this plain. Full article

(This article belongs to the Special Issue Sediment Pollution Process and Microbial Responses in Aquatic Environment)

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36 pages, 10270 KiB

Open AccessArticle

Spatiotemporal Analysis of Water Quality and Optical Changes Induced by Contaminants in Lake Chinchaycocha Using Sentinel-2 and in Situ Data

by Emerson Espinoza, Analy Baltodano and Norvin Requena

Water 2025, 17(15), 2195; https://doi.org/10.3390/w17152195 - 23 Jul 2025

Abstract

Lake Chinchaycocha, Peru’s second-largest high-altitude lake and a Ramsar-designated wetland of international importance, is increasingly threatened by anthropogenic pollution and hydroclimatic shifts. This study integrates Sentinel-2 multispectral imagery with in situ water quality data from Peru’s National Water Observatory to assess spatiotemporal dynamics [...] Read more.

Lake Chinchaycocha, Peru’s second-largest high-altitude lake and a Ramsar-designated wetland of international importance, is increasingly threatened by anthropogenic pollution and hydroclimatic shifts. This study integrates Sentinel-2 multispectral imagery with in situ water quality data from Peru’s National Water Observatory to assess spatiotemporal dynamics in 31 physicochemical parameters between 2018 and 2024. We evaluated 40 empirical algorithms developed globally for Sentinel-2 and tested their transferability to this ultraoligotrophic Andean system. The results revealed limited predictive accuracy, underscoring the need for localized calibration. Subsequently, we developed and validated site-specific models for ammoniacal nitrogen, electrical conductivity, major ions, and trace metals, achieving high predictive performance during the rainy season (R² up to 0.95). Notably, the study identifies consistent seasonal correlations—such as between total copper and ammoniacal nitrogen—and strong spectral responses in Band 1, linked to runoff dynamics. These findings highlight the potential of combining public monitoring data with remote sensing to enable scalable, cost-effective assessment of water quality in optically complex, high-Andean lakes. The study provides a replicable framework for integrating national datasets into operational monitoring and environmental policy. Full article

(This article belongs to the Special Issue Water Pollution Monitoring, Modelling and Management)

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21 pages, 3469 KiB

Open AccessArticle

Monitoring Phosphorus During High Flows: Critical for Implementing Surrogacy Models

by Elliot S. Anderson, Keith E. Schilling and Larry J. Weber

Water 2025, 17(15), 2194; https://doi.org/10.3390/w17152194 - 23 Jul 2025

Abstract

Phosphorus (P) is a problematic waterborne pollutant, and considerable efforts have been taken to monitor its presence and transport in locales struggling with eutrophication. Most historical P datasets consist of intermittent grab samples, necessitating the construction of surrogacy models to explore P at [...] Read more.

Phosphorus (P) is a problematic waterborne pollutant, and considerable efforts have been taken to monitor its presence and transport in locales struggling with eutrophication. Most historical P datasets consist of intermittent grab samples, necessitating the construction of surrogacy models to explore P at high resolutions. In Iowa, models using historical data to relate turbidity to particulate P (PartP) have successfully been created. However, it is unknown how comprehensively historical datasets reflect Iowa’s hydrologic conditions and how well these models perform during flows not well represented within the existing data. In this study, we analyzed historical P datasets from 16 major Iowa rivers to determine how well they captured the rivers’ full range of streamflow conditions. While these datasets contained sufficient samples during low and average flows, they typically under-sampled high flows—containing few values above the 85–95th percentiles. Therefore, we collected new data in each river during wet conditions, with ~300 samples taken from 2021 to 2024. These new sampling results largely aligned with the existing surrogacy models and slightly improved model performance, suggesting that utilizing turbidity to predict PartP is appropriate in nearly all streamflow conditions. These findings may prove consequential for robustly modeling PartP due to its dynamic nature and disproportionately high transport during wet weather events. Full article

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23 pages, 2274 KiB

Open AccessReview

Nature-Based Solutions for Water Management in Europe: What Works, What Does Not, and What’s Next?

by Eleonora Santos

Water 2025, 17(15), 2193; https://doi.org/10.3390/w17152193 - 23 Jul 2025

Abstract

Nature-based solutions (NbS) are increasingly recognized as strategic alternatives and complements to grey infrastructure for addressing water-related challenges in the context of climate change, urbanization, and biodiversity decline. This article presents a critical, theory-informed review of the state of NbS implementation in European [...] Read more.

Nature-based solutions (NbS) are increasingly recognized as strategic alternatives and complements to grey infrastructure for addressing water-related challenges in the context of climate change, urbanization, and biodiversity decline. This article presents a critical, theory-informed review of the state of NbS implementation in European water management, drawing on a structured synthesis of empirical evidence from regional case studies and policy frameworks. The analysis found that while NbS are effective in reducing surface runoff, mitigating floods, and improving water quality under low- to moderate-intensity events, their performance remains uncertain under extreme climate scenarios. Key gaps identified include the lack of long-term monitoring data, limited assessment of NbS under future climate conditions, and weak integration into mainstream planning and financing systems. Existing evaluation frameworks are critiqued for treating NbS as static interventions, overlooking their ecological dynamics and temporal variability. In response, a dynamic, climate-resilient assessment model is proposed—grounded in systems thinking, backcasting, and participatory scenario planning—to evaluate NbS adaptively. Emerging innovations, such as hybrid green–grey infrastructure, adaptive governance models, and novel financing mechanisms, are highlighted as key enablers for scaling NbS. The article contributes to the scientific literature by bridging theoretical and empirical insights, offering region-specific findings and recommendations based on a comparative analysis across diverse European contexts. These findings provide conceptual and methodological tools to better design, evaluate, and scale NbS for transformative, equitable, and climate-resilient water governance. Full article

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18 pages, 6088 KiB

Open AccessArticle

Hydrochemical Characteristics and Evolution of Underground Brine During Mining Process in Luobei Mining Area of Lop Nur, Northwestern China

by Xu Han, Yufei Deng, Hao Geng, Liangliang Zhao, Ji Zhang, Lingfen Wang, Lei Wang, Xiaohong Sun, Zihao Zhou, Meng Wang and Zhongjian Liu

Water 2025, 17(15), 2192; https://doi.org/10.3390/w17152192 - 23 Jul 2025

Abstract

Underground brine as a liquid mineral resource available for development and utilization has attracted widespread attention. However, how the mining process affects the hydrochemical characteristics and evolution of underground brine has yet to be fully understood. Herein, 207 underground brine samples were collected [...] Read more.

Underground brine as a liquid mineral resource available for development and utilization has attracted widespread attention. However, how the mining process affects the hydrochemical characteristics and evolution of underground brine has yet to be fully understood. Herein, 207 underground brine samples were collected from the Luobei mining area of the Lop Nur region during pre-exploitation (2006), exploitation (2019), and late exploitation (2023) to explore the dynamic change characteristics and evolution mechanisms of the underground brine hydrochemistry using the combination of statistical analysis, spatial interpolation, correlation analysis, and ion ratio analysis. The results indicated that Na⁺ and Cl⁻ were the dominant ionic components in the brine, and their concentrations remained relatively stable throughout the mining process. However, the content of Mg²⁺ increased gradually during the mining process (increased by 45.08% in the middle stage and 3.09% in the later stage). The elevation in Mg²⁺ concentration during the mining process could be attributed to the dissolution of Mg-bearing minerals, reverse cation exchange, and mixed recharge. This research furnishes a scientific foundation for a more in-depth comprehension of the disturbance mechanism of brine-mining activities on the groundwater chemical system in the mining area and for the sustainable exploitation of brine resources. Full article

(This article belongs to the Topic The Hydrosphere in Crisis: Human Impact, Climate Change, and Pathways to Resilience, 2nd Edition)

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25 pages, 1882 KiB

Open AccessArticle

An Assessment of Collector-Drainage Water and Groundwater—An Application of CCME WQI Model

by Nilufar Rajabova, Vafabay Sherimbetov, Rehan Sadiq and Alaa Farouk Aboukila

Water 2025, 17(15), 2191; https://doi.org/10.3390/w17152191 - 23 Jul 2025

Abstract

According to Victor Ernest Shelford’s ‘Law of Tolerance,’ organisms within ecosystems thrive optimally when environmental conditions are favorable. Applying this principle to ecosystems and agro-ecosystems facing water scarcity or environmental challenges can significantly enhance their productivity. In these ecosystems, phytocenosis adjusts its conditions [...] Read more.

According to Victor Ernest Shelford’s ‘Law of Tolerance,’ organisms within ecosystems thrive optimally when environmental conditions are favorable. Applying this principle to ecosystems and agro-ecosystems facing water scarcity or environmental challenges can significantly enhance their productivity. In these ecosystems, phytocenosis adjusts its conditions by utilizing water with varying salinity levels. Moreover, establishing optimal drinking water conditions for human populations within an ecosystem can help mitigate future negative succession processes. The purpose of this study is to evaluate the quality of two distinct water sources in the Amudarya district of the Republic of Karakalpakstan, Uzbekistan: collector-drainage water and groundwater at depths of 10 to 25 m. This research is highly relevant in the context of climate change, as improper management of water salinity, particularly in collector-drainage water, may exacerbate soil salinization and degrade drinking water quality. The primary methodology of this study is as follows: The Food and Agriculture Organization of the United Nations (FAO) standard for collector-drainage water is applied, and the water quality index is assessed using the CCME WQI model. The Canadian Council of Ministers of the Environment (CCME) model is adapted to assess groundwater quality using Uzbekistan’s national drinking water quality standards. The results of two years of collected data, i.e., 2021 and 2023, show that the water quality index of collector-drainage water indicates that it has limited potential for use as secondary water for the irrigation of sensitive crops and has been classified as ‘Poor’. As a result, salinity increased by 8.33% by 2023. In contrast, groundwater quality was rated as ‘Fair’ in 2021, showing a slight deterioration by 2023. Moreover, a comparative analysis of CCME WQI values for collector-drainage and groundwater in the region, in conjunction with findings from Ethiopia, India, Iraq, and Turkey, indicates a consistent decline in water quality, primarily due to agriculture and various other anthropogenic pollution sources, underscoring the critical need for sustainable water resource management. This study highlights the need to use organic fertilizers in agriculture to protect drinking water quality, improve crop yields, and promote soil health, while reducing reliance on chemical inputs. Furthermore, adopting WQI models under changing climatic conditions can improve agricultural productivity, enhance groundwater quality, and provide better environmental monitoring systems. Full article

(This article belongs to the Topic Hydrology and Water Resources in Agriculture and Ecology—2nd Edition)

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15 pages, 12546 KiB

Open AccessArticle

Retrieval of Chlorophyll-a Concentration in Nanyi Lake Using the AutoGluon Framework

by Weibin Gu, Ji Liang, Lian Yang, Shanshan Guo and Ruixin Jia

Water 2025, 17(15), 2190; https://doi.org/10.3390/w17152190 - 23 Jul 2025

Abstract

The chlorophyll-a (Chl-a) concentration in lakes is a crucial parameter for monitoring water quality and assessing phytoplankton abundance. However, accurately retrieving Chl-a concentrations remains a significant challenge in remote sensing. To address the limitations of existing methods in terms of modeling efficiency and [...] Read more.

The chlorophyll-a (Chl-a) concentration in lakes is a crucial parameter for monitoring water quality and assessing phytoplankton abundance. However, accurately retrieving Chl-a concentrations remains a significant challenge in remote sensing. To address the limitations of existing methods in terms of modeling efficiency and adaptability, this study focuses on Lake Nanyi in Anhui Province. By integrating Sentinel-2 satellite imagery with in situ water quality measurements and employing the AutoML framework AutoGluon, a Chl-a inversion model based on narrow-band spectral features is developed. Feature selection and model ensembling identify bands B6 (740 nm) and B7 (783 nm) as the optimal combination, which are then applied to multi-temporal imagery from October 2022 to generate spatial mean distributions of Chl-a in Lake Nanyi. The results demonstrate that the AutoGluon framework significantly outperforms traditional methods in both model accuracy (R²: 0.94, RMSE: 1.67

μ

g/L) and development efficiency. The retrieval results reveal spatial heterogeneity in Chl-a concentration, with higher concentrations observed in the southern part of the western lake and the western side of the eastern lake, while the central lake area exhibits relatively lower concentrations, ranging from 3.66 to 21.39

μ

g/L. This study presents an efficient and reliable approach for lake ecological monitoring and underscores the potential of AutoML in water color remote sensing applications. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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