Water

13 pages, 1663 KB

Open AccessArticle

L-Lysine-Modified Lignin for Polishing Alkaline Road-Marking Wash Water: High Uptake of Cationic Dyes with Acid-Enabled Regeneration

by Zeyu Xiong and Peng Jing

Water 2025, 17(22), 3234; https://doi.org/10.3390/w17223234 (registering DOI) - 12 Nov 2025

Abstract

Road-marking operations generate alkaline wash water with intense color and soluble cationic additives. A new biomass adsorption material (LML) was developed to address dye pollution in road-marking wash water effectively. Enzymatically hydrolyzed lignin was used as the raw material for the first time. [...] Read more.

Road-marking operations generate alkaline wash water with intense color and soluble cationic additives. A new biomass adsorption material (LML) was developed to address dye pollution in road-marking wash water effectively. Enzymatically hydrolyzed lignin was used as the raw material for the first time. L-lysine was modified to the structure of the lignin benzene ring using a simple one-step synthesis method, which endowed lignin with a large number of active carboxyl and amino functional groups to improve its adsorption capacity. The adsorption performance of LML for methylene blue in water was also investigated. The experimental results show that the LML has a high dye removal rate under alkaline conditions. The fitted adsorption model shows that the saturated adsorption capacity of LML for methylene blue (MB) is

129.4

m

g

/

g

and malachite green (MG) is

244.9

m

g

/

g

, which is in line with the Langmuir isotherm adsorption model. The adsorption process is endothermic, which means that the adsorption capacity increases with increasing temperature. Kinetic studies showed that the adsorption process reached equilibrium within 120

\min

following a pseudo-second-order kinetic model. The cycle experiment shows that the removal efficiency of the adsorbent for dyes can still reach 90 after five cycles, indicating a good practical application value for the polishing of road-marking wash water. Full article

18 pages, 2833 KB

Open AccessArticle

Empirical Recalibration of Hunter’s Method for Peak Flow Estimation in Institutional Buildings: A Pilot Study in Data-Scarce Contexts

by Christian Mera-Parra and Holger Manuel Benavides-Muñoz

Water 2025, 17(22), 3233; https://doi.org/10.3390/w17223233 (registering DOI) - 12 Nov 2025

Abstract

Accurate estimation of peak water demand remains a challenge in institutional settings with floating populations, particularly in regions where design standards may require revision and validation to accommodate evolving consumption patterns. This pilot study assesses the potential of a probabilistic adaptation of Hunter’s [...] Read more.

Accurate estimation of peak water demand remains a challenge in institutional settings with floating populations, particularly in regions where design standards may require revision and validation to accommodate evolving consumption patterns. This pilot study assesses the potential of a probabilistic adaptation of Hunter’s method, calibrated through high-resolution flow and pressure monitoring, for peak flow estimation in five academic buildings in Loja, Ecuador. Over 62 days, usage parameters, duration (t), frequency (i), and peak period (h), were disaggregated from 1 min interval data to derive building-specific binomial probability distributions. The adapted model was compared against three benchmarks: the Neyman–Scott Rectangular Pulse Model (NSRPM), the Water Demand Calculator (WDC), and Ecuador’s Hydro-Sanitary Standard (NHE 2011). Results indicate the proposed approach estimates peak flows within −11.6% to +20.0% of observed values, outperforming WDC (systematic underestimation up to −81.5%) and NHE 2011 (average underestimation of −31.3%), though NSRPM achieved high accuracy for one site (−1.1%) with high inter-building variability (average −38.4%). While limited to a small sample in a single climatic context, this pilot demonstrates that temporal disaggregation of stochastic demand enables a context-sensitive recalibration of Hunter’s method, offering a methodologically sound basis for future validation across diverse institutional settings in the Global South. Full article

(This article belongs to the Section Urban Water Management)

► Show Figures

Figure 1

22 pages, 19130 KB

Open AccessArticle

Numerical Simulation of Groundwater Regulation in Arid Oasis Regions: A Case Study of the Shihezi Irrigation District, Xinjiang

by Jun Zhang, Yingli Xia, Xiaolong Li, Yongwei Zhang, Qinglin Li, Wenzan Wang and Guang Yang

Water 2025, 17(22), 3232; https://doi.org/10.3390/w17223232 (registering DOI) - 12 Nov 2025

Abstract

The optimal groundwater level is critical for maintaining the coordinated and healthy development of the ecological–agricultural production system in arid oasis regions. This study comprehensively considered factors such as ecological safety, soil salinization prevention and control, and ground subsidence constraints to determine the [...] Read more.

The optimal groundwater level is critical for maintaining the coordinated and healthy development of the ecological–agricultural production system in arid oasis regions. This study comprehensively considered factors such as ecological safety, soil salinization prevention and control, and ground subsidence constraints to determine the optimal groundwater level in a region. GIS technology and Visual MODFLOW Flex 6.1 software were used to construct a three-dimensional groundwater numerical model, and regional comprehensive evaluation values were applied to simulate and predict the spatiotemporal evolution of groundwater levels under different regulation schemes. Results indicated the following: (1) There were significant spatial differences in the study area. The optimal groundwater depths in agricultural and engineering/living areas were 2–4 and 3–4 m, respectively, as determined using methods such as capillary rise height and total sum of middle layers. (2) In long-term (≥10a) regulation, areas with a reduced regional comprehensive evaluation value > 0.20 exhibited the highest groundwater recharge rate (17.10%), while those with a reduced regional comprehensive evaluation value > 0.32 showed the best coverage of optimal groundwater levels. The opposite trend was observed in short-term regulation. (3) Considering both groundwater recharge and optimal groundwater level regulation, the Y₂ scheme demonstrated the best regulation effect. The findings of this study can provide theoretical references for the multi-objective optimization management of water resources in arid oasis regions. Full article

(This article belongs to the Special Issue Advances in Ecohydrology in Arid Inland River Basins, 2nd Edition)

25 pages, 2046 KB

Open AccessArticle

Evaluation of the Impact of Sustainable Drainage Systems (SuDSs) on Stormwater Drainage Network Using Giswater: A Case Study in the Metropolitan Area of Barcelona, Spain

by Suelen Ferreira de Araújo, Rui Lança, Carlos Otero Silva, Xavier Torret, Fernando Miguel Granja-Martins and Helena Maria Fernandez

Water 2025, 17(22), 3231; https://doi.org/10.3390/w17223231 (registering DOI) - 12 Nov 2025

Abstract

To mitigate the impacts of urbanisation and the attendant surface sealing, appropriate measures are required when adapting urban spaces and drainage infrastructure. In this context, the deployment of Sustainable Drainage Systems (SuDSs) has emerged as a viable alternative, delivering highly positive outcomes by [...] Read more.

To mitigate the impacts of urbanisation and the attendant surface sealing, appropriate measures are required when adapting urban spaces and drainage infrastructure. In this context, the deployment of Sustainable Drainage Systems (SuDSs) has emerged as a viable alternative, delivering highly positive outcomes by enhancing hydrological, hydraulic and landscape performance while restoring ecosystem services to the community. This study evaluates the relative performance of five SuDS typologies, green roofs, bioretention cells, infiltration trenches, permeable pavements, and rain barrels, implemented in a 64 ha subbasin of the metropolitan area of Barcelona, Spain. Using Giswater integrated with the SWMM, the stormwater drainage network was modelled under multiple rainfall scenarios. Performance was assessed using two qualitative indicators, the junction index (I_j) and the conduit index (I_c), which measure surcharge levels in manholes and pipes, respectively. The results show that SuDS implementation affecting 42.8% of the drained area can enhance network performance by 35.6% and reduce flooded junctions by 67%. Among the typologies, rain barrels and bioretention cells were the most effective. The study concludes that SuDS construction, supported by open-source tools and performance-based indicators, constitutes a replicable and technically robust strategy for mitigating the effects of surface sealing and increasing urban resilience. Full article

(This article belongs to the Section Urban Water Management)

18 pages, 2290 KB

Open AccessArticle

Effect of Microwave Treatment on Physicochemical Properties and Subsequent Anaerobic Digestion of Fecal Sludge

by Principal Mdolo, Jon Pocock and Konstantina Velkushanova

Water 2025, 17(22), 3230; https://doi.org/10.3390/w17223230 - 12 Nov 2025

Abstract

Fecal sludge (FS) requires effective management to mitigate environmental and public health risks and enable resource recovery. This study evaluated the effects of microwave (MW) treatment on FS characteristics and subsequent anaerobic digestion (AD) performance. MW treatment raised FS temperatures to ~96 °C, [...] Read more.

Fecal sludge (FS) requires effective management to mitigate environmental and public health risks and enable resource recovery. This study evaluated the effects of microwave (MW) treatment on FS characteristics and subsequent anaerobic digestion (AD) performance. MW treatment raised FS temperatures to ~96 °C, reducing FS volume by 50% and inducing three thermal phases. Soluble chemical oxygen demand (sCOD) showed a multi-phase pattern, with a maximum solubilization of 29.8% during initial heating due to the solubilization of proteins and carbohydrates. Scanning electron microscopy (SEM) revealed morphological changes, while Fourier transform infrared (FTIR) spectroscopy confirmed that core functional groups remained unchanged. MW-pretreated FS enhanced AD performance, achieving a 17% increase in cumulative methane yield, alongside 18% and 33% improvements in organic loading and methane production rates, respectively. MW treatment influenced the phase distribution of digestate components, showing a shift in nutrient portioning towards the liquid fraction. These results suggest that integrating MW pretreatment into FS management systems can improve energy recovery, reduce treatment costs, and support resource-efficient sanitation solutions. Full article

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

► Show Figures

Figure 1

27 pages, 2553 KB

Open AccessArticle

Sustainable Dye Removal Using Date Stones and Adsorption Process Optimization: Factorial Design, Kinetics, and Isotherm Analysis

by Lassaad Mechi, Souad Rezma, Malak Kahloul, Jalila Chékir, Hajer Chemingui, Hanen Azaza, Abdulmohsen K. D. AlSukaibi and Neila Saidi

Water 2025, 17(22), 3229; https://doi.org/10.3390/w17223229 - 12 Nov 2025

Abstract

This study aims to present the preparation of date stone activated carbon (DSAC) through physical activation with carbon dioxide. The Brunauer–Emmett–Teller (BET) technique, Boehm titrations, elemental analysis, Raman and Fourier-transform infrared (FTIR) spectroscopy have been used to characterize the raw material (date stone), [...] Read more.

This study aims to present the preparation of date stone activated carbon (DSAC) through physical activation with carbon dioxide. The Brunauer–Emmett–Teller (BET) technique, Boehm titrations, elemental analysis, Raman and Fourier-transform infrared (FTIR) spectroscopy have been used to characterize the raw material (date stone), date stone activated carbon (DSAC) produced, Congo Red (CR) and to investigate the adsorption phenomena. The study of the DSAC porous material revealed the dominance of micropores with a specific surface area greater than 535.9 m² g⁻¹ and an approximate volume value equal to 0.208 cm³ g⁻¹. The Langmuir model predicted an adsorption capacity of approximately 27.77 mg g⁻¹, while a 90% removal efficiency for CR dye was achieved under neutral pH conditions. Thermodynamic analysis confirmed that the adsorption of CR on DSAC has a spontaneous (ΔG° < 0) and exothermic (ΔH° < 0) character. The adsorption mechanism of CR on DSAC was proposed and discussed, based on the determination of electrostatic interactions being identified as a critical factor that controls the adsorption phenomenon of CR on DSAC. A 2³ full factorial design was implemented to systematically investigate the effects of three critical parameters (temperature, adsorbent dosage, and pH) on the adsorption performance. Statistical analysis indicated that all three primary factors significantly influenced the results. The square correlation coefficient of the model (R²-sq of 97.26%) was in good agreement with the statistical model. The variable is considered statistically significant when the p-value is lower than 0.05. These findings, supported by experimental data, strongly indicate that DSAC possesses remarkable potential as a sustainable and effective bio-adsorbent for wastewater remediation applications capable of removing diverse contaminants with high efficiency. Full article

(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment (2nd Edition))

► Show Figures

Figure 1

18 pages, 1952 KB

Open AccessReview

Comprehensive Review on the Distribution, Environmental Fate, and Risks of Antibiotic Resistance Genes in Rivers and Lakes of China

by Jingjie Sun, Cancan Xu, Dongmei Wang, Dongsheng Liu, Guomin Chen, Shiwen Zhao, Jinshan Gao, Yifan Shi, Keyang Jiang, Jiaxin Xu, Zixuan Ma, Yang Chen and Zhiyuan Wang

Water 2025, 17(22), 3228; https://doi.org/10.3390/w17223228 - 12 Nov 2025

Abstract

Antibiotic resistance genes (ARGs) have emerged as globally concerning environmental contaminants, posing serious threats to ecosystem health and public safety. This systematic review summarizes global research trends on ARGs across three key aspects: (i) identification and distribution in river and lake ecosystems, (ii) [...] Read more.

Antibiotic resistance genes (ARGs) have emerged as globally concerning environmental contaminants, posing serious threats to ecosystem health and public safety. This systematic review summarizes global research trends on ARGs across three key aspects: (i) identification and distribution in river and lake ecosystems, (ii) sources and environmental behaviors, and (iii) ecological and human health risks. Concentration data of ARGs in various rivers and lakes across China were compiled to reveal their spatial distribution patterns. The analysis of ARGs sources and environmental behaviors provides essential insights for designing effective mitigation strategies. Furthermore, this review highlights the potential ecological and human health hazards of ARGs and discusses limitations and improvement directions of current risk assessment methodologies. The main findings indicate that ARGs are widely present in rivers and lakes across China; higher abundances occur in eastern and southern regions compared with central–western and northern areas, such as 4.93 × 10²–8.10 × 10³ copies/mL in Qinghai Lake and 6.7 × 10⁷–1.76 × 10⁸ copies/mL in Taihu Lake. The environmental behaviors of ARGs are highly complex, involving multiple mechanisms and influenced by climatic conditions, nutrient levels, and additional environmental factors. Based on these findings, future efforts should prioritize long-term site-specific monitoring, evaluate their prolonged impacts on aquatic ecosystems, and develop integrated risk assessment models to support evidence-based environmental management. 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)

► Show Figures

Figure 1

26 pages, 14034 KB

Open AccessArticle

Interannual Variability in Seasonal Sea Surface Temperature and Chlorophyll a in Priority Marine Regions of the Northwest of Mexico

by Carlos Manuel Robles-Tamayo, José Raúl Romo-León, Ricardo García-Morales, Gudelia Figueroa-Preciado, Luis Fernando Enríquez-Ocaña and María Cristina Peñalba-Garmendia

Water 2025, 17(22), 3227; https://doi.org/10.3390/w17223227 - 11 Nov 2025

Abstract

The northwest of Mexico has important zones for biodiversity conservation, denominated Priority Marine Regions (PMRs), and to study key oceanographic features related to ecological structure, it is necessary to understand environmental variability and observe climatic trends. Sea Surface Temperature (SST) is tightly associated [...] Read more.

The northwest of Mexico has important zones for biodiversity conservation, denominated Priority Marine Regions (PMRs), and to study key oceanographic features related to ecological structure, it is necessary to understand environmental variability and observe climatic trends. Sea Surface Temperature (SST) is tightly associated with photosynthesis and serves as a control and driver for biological processes linked to the phytoplankton. Global climatic systems, like El Niño Southern Oscillation (ENSO), are responsible for the interannual and interdecadal variation in SST, since global circulation is modified by them. An important metric to assess phytoplanktonic biomass/photosynthesis is Chlorophyll a (Chl a), constituting the primary basis of the marine trophic web. The present study aims to examine the interannual oceanographic variability across 24 PMRs by employing monthly SST (°C) and Chl a (mg/m³) data derived from remote sensing instruments with spatial resolution of 4 km and 1 km from September 1997 to October 2018. We grouped the Priority Marine Regions into 18 main areas, based on a cluster analysis of Sea Surface Temperature. Significant differences were observed, showing higher SST levels during El Niño phase and higher Chl a concentration during La Niña phase, primarily in winter and spring, which will impact marine ecosystems. Full article

(This article belongs to the Special Issue Remote Sensing in Coastal Water Environment Monitoring)

► Show Figures

Figure 1

30 pages, 2460 KB

Open AccessArticle

Deep Reinforcement Learning for Optimized Reservoir Operation and Flood Risk Mitigation

by Fred Sseguya and Kyung Soo Jun

Water 2025, 17(22), 3226; https://doi.org/10.3390/w17223226 - 11 Nov 2025

Abstract

Effective reservoir operation demands a careful balance between flood risk mitigation, water supply reliability, and operational stability, particularly under evolving hydrological conditions. This study applies deep reinforcement learning (DRL) models—Deep Q-Network (DQN), Proximal Policy Optimization (PPO), and Deep Deterministic Policy Gradient (DDPG)—to optimize [...] Read more.

Effective reservoir operation demands a careful balance between flood risk mitigation, water supply reliability, and operational stability, particularly under evolving hydrological conditions. This study applies deep reinforcement learning (DRL) models—Deep Q-Network (DQN), Proximal Policy Optimization (PPO), and Deep Deterministic Policy Gradient (DDPG)—to optimize reservoir operations at the Soyang River Dam, South Korea, using 30 years of daily hydrometeorological data (1993–2022). The DRL framework integrates observed and remotely sensed variables such as precipitation, temperature, and soil moisture to guide adaptive storage decisions. Discharge is computed via mass balance, preserving inflow while optimizing system responses. Performance is evaluated using cumulative reward, action stability, and counts of total capacity and flood control violations. PPO achieved the highest cumulative reward and the most stable actions but incurred six flood control violations; DQN recorded one flood control violation, reflecting larger buffers and strong flood control compliance; DDPG provided smooth, intermediate responses with one violation. No model exceeded the total storage capacity. Analyses show a consistent pattern: retain on the rise, moderate the crest, and release on the recession to keep Flood Risk (FR) < 0. During high-inflow days, DRL optimization outperformed observed operation by increasing storage buffers and typically reducing peak discharge, thereby mitigating flood risk. Full article

(This article belongs to the Special Issue Machine Learning Applications in the Water Domain)

24 pages, 8704 KB

Open AccessArticle

Machine Learning-Based Forecasting of Wastewater Inflow During Rain Events at a Spanish Mediterranean Coastal WWTPs

by Alejandro González Barberá, Sergio Iserte, Maribel Castillo, Jaume Luis-Gómez, Raúl Martínez-Cuenca, Guillem Monrós-Andreu and Sergio Chiva

Water 2025, 17(22), 3225; https://doi.org/10.3390/w17223225 - 11 Nov 2025

Abstract

Forecasting influent flow in Wastewater Treatment Plants (WWTPs) is critical for managing operational risks during flash floods, especially in Spain’s Mediterranean coastal regions. These facilities, essential for public health and environmental protection, are vulnerable to abrupt inflow surges caused by heavy rainfall. This [...] Read more.

Forecasting influent flow in Wastewater Treatment Plants (WWTPs) is critical for managing operational risks during flash floods, especially in Spain’s Mediterranean coastal regions. These facilities, essential for public health and environmental protection, are vulnerable to abrupt inflow surges caused by heavy rainfall. This study proposes a data-driven approach combining historical flow and rainfall data to predict short-term inflow dynamics. Several models were evaluated, including Random Forest, XGBoost, CatBoost, and LSTM, using metrics such as Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and R-squared (R²). XGBoost outperformed the others, particularly under severe class imbalance, with only 1% of the data representing rainfall events. Hyperparameter tuning and input window size analysis revealed that accurate predictions are achievable with just 14 days of training data from a 10-year (2012–2022) dataset sourced from a single WWTP and on-site weather station. The proposed framework supports proactive WWTP management during extreme weather events. Full article

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

► Show Figures

Figure 1

14 pages, 2004 KB

Open AccessArticle

Spatiotemporal Patterns, Characteristics, and Ecological Risk of Microplastics in the Surface Waters of Shijiu Lake (Nanjing, China)

by Jie Ji, Juan Huang, Ming Chen, Hui Jin, Xinyue Wang, Yufeng Wu, Xiuwen Qian, Haoqin Ma and Jin Xu

Water 2025, 17(22), 3224; https://doi.org/10.3390/w17223224 - 11 Nov 2025

Abstract

Microplastics (MPs) are pervasive in freshwater and may threaten aquatic ecosystem health. We surveyed surface waters of Shijiu Lake and its inflowing tributaries during the dry (January–March) and rainy (May–July) seasons of 2024. MP abundance ranged within 17.54–30.93 items/L, with higher values in [...] Read more.

Microplastics (MPs) are pervasive in freshwater and may threaten aquatic ecosystem health. We surveyed surface waters of Shijiu Lake and its inflowing tributaries during the dry (January–March) and rainy (May–July) seasons of 2024. MP abundance ranged within 17.54–30.93 items/L, with higher values in the rainy than in the dry season (28.18 ± 6.03 vs. 24.53 ± 5.68 items/L; one-way ANOVA, p < 0.05). Abundance correlated positively with turbidity (r = 0.44; R² = 0.20; p < 0.05), whereas associations with total nitrogen, total phosphorus, and suspended solids were not significant (p > 0.05). Small particles (38–75 μm) dominated and were slightly more prevalent in the dry season, while the fraction of larger particles (>150 μm) was relatively higher in the rainy season. Granules predominated across sites, but their share decreased in the rainy season, accompanied by a notable increase in fibers. The Pollution Load Index (PLI) indicated slight but spatially uneven pollution (PLI = 1.00–1.43), generally higher during the rainy season and consistently elevated at the lake center; the Nongkan River exhibited the lowest levels. Ecologically, the patterns indicate rainfall-driven inputs and hydrodynamic controls (runoff, resuspension, residence time), identifying the lake center and tributary interfaces as priority zones for monitoring and mitigation. These results provide lake-scale evidence to refine seasonal monitoring and inform source-reduction strategies in similar inland waters. Full article

(This article belongs to the Section Ecohydrology)

► Show Figures

Figure 1

21 pages, 3408 KB

Open AccessArticle

Entropy-Generation-Based Optimization of Elbow Suction Conduit for Mixed-Flow Pumps

by Na Yan, Xianzhu Wei, Xiaohang Wang, Guolong Fu and Rui Zhang

Water 2025, 17(22), 3223; https://doi.org/10.3390/w17223223 - 11 Nov 2025

Abstract

The elbow suction conduit plays a decisive role in determining inflow conditions, thereby influencing a pump’s efficiency and cavitation characteristics. The complex three-dimensional swirling and separating flow makes pinpointing the sources and mechanisms of energy dissipation challenging. This study aims to accurately diagnose [...] Read more.

The elbow suction conduit plays a decisive role in determining inflow conditions, thereby influencing a pump’s efficiency and cavitation characteristics. The complex three-dimensional swirling and separating flow makes pinpointing the sources and mechanisms of energy dissipation challenging. This study aims to accurately diagnose the sources of hydraulic losses within the elbow suction conduit and conduct effective geometric optimization to enhance overall pump performance. Entropy production theory was integrated with three-dimensional Reynolds-averaged Navier-Stokes simulations to quantitatively analyze the irreversible energy dissipation in different parts of the conduit. Results reveal that energy dissipation is predominantly concentrated at the inlet section, wall surfaces, outer curvature of the bend, and the inner conical diffuser. Key geometric parameters were systematically optimized. Compared to the baseline design, the optimized configuration not only reduced entropy generation induced by wall shear and turbulent fluctuations but also improved the spatio-temporal uniformity of the outflow. Consequently, this translated directly into enhanced overall pump performance: the optimized design shows a 0.34% increase in efficiency and a 3.6% reduction in the inception cavitation coefficient at the rated condition, leading to lower energy consumption and enhanced operational reliability. The effectiveness of entropy production analysis for the hydraulic optimization of pumps was demonstrated. Full article

(This article belongs to the Special Issue Hydraulics and Hydrodynamics in Fluid Machinery, 2nd Edition)

► Show Figures

Figure 1

23 pages, 22503 KB

Open AccessArticle

Enhancing Flood Inundation Simulation Under Rapid Urbanisation and Data Scarcity: The Case of the Lower Prek Thnot River Basin, Cambodia

by Takuto Kumagae, Monin Nong, Toru Konishi, Hideo Amaguchi and Yoshiyuki Imamura

Water 2025, 17(22), 3222; https://doi.org/10.3390/w17223222 - 11 Nov 2025

Abstract

Flooding poses a major hazard to rapidly urbanising cities in Southeast Asia, and risks are projected to intensify under climate change. Accurate risk assessment, however, is hindered by scarcity of hydrological and topographic data. Focusing on the Lower Prek Thnot River Basin, a [...] Read more.

Flooding poses a major hazard to rapidly urbanising cities in Southeast Asia, and risks are projected to intensify under climate change. Accurate risk assessment, however, is hindered by scarcity of hydrological and topographic data. Focusing on the Lower Prek Thnot River Basin, a peri-urban catchment of Phnom Penh, Cambodia, the study applied the Rainfall–Runoff–Inundation model and systematically augmented inputs: hourly satellite rainfall data, field-surveyed river cross-sections and representation of hydraulic infrastructure such as weirs and pumping. Validation used Sentinel-1 SAR-derived flood-extent maps for the October 2020 event. Scenario comparison shows that rainfall input and channel geometry act synergistically: omitting either degrades performance and spatial realism. The best configuration (Sim. 5) Accuracy = 0.891, Hit Ratio = 0.546 and True Ratio = 0.701 against Sentinel-1, and reproduced inundation upstream of weirs while reducing overestimation in urban districts through pumping emulation. At the study’s 500 m grid, updating land use from 2002 to 2020 had only a minor effect relative to rainfall, geometry and infrastructure. The results demonstrate that targeted data augmentation—combining satellite products, field surveys and operational infrastructure—can deliver robust inundation maps under data scarcity, supporting hazard mapping and resilience-oriented flood management in rapidly urbanising basins. Full article

(This article belongs to the Special Issue Water-Related Disasters in Adaptation to Climate Change)

► Show Figures

Figure 1

17 pages, 3868 KB

Open AccessArticle

Prolonged Summer Daytime Dissolved Oxygen Recovery in a Eutrophic Lake: High-Frequency Monitoring Diel Evidence from Taihu Lake, China

by Dong Xie, Xiaojie Chen, Yi Qian and Yuqing Feng

Water 2025, 17(22), 3221; https://doi.org/10.3390/w17223221 - 11 Nov 2025

Abstract

In eutrophic shallow lakes, dissolved oxygen (DO) exhibits significant temporal variations, regulated by the combined effects of photosynthesis and water temperature (WT). High-frequency monitoring enables a detailed capture of DO diel cycles, providing a more comprehensive understanding of the dynamic changes within lake [...] Read more.

In eutrophic shallow lakes, dissolved oxygen (DO) exhibits significant temporal variations, regulated by the combined effects of photosynthesis and water temperature (WT). High-frequency monitoring enables a detailed capture of DO diel cycles, providing a more comprehensive understanding of the dynamic changes within lake ecosystems. This study involved high-frequency (10 min intervals) in situ monitoring of DO over a three-year period (2020–2022) in the littoral zone of Taihu Lake, China. Random forest regression analysis identified WT, photosynthetically active radiation (PAR), and relative humidity (RH) as the three most influential variables governing DO dynamics. The relative importance of these factors varied seasonally (0.117–0.392), with PAR dominating in summer (0.383), whereas WT had the highest importance in other seasons (0.312–0.392). Cusum analysis further revealed that the DO-WT relationship changed from a dome-shaped pattern in spring, autumn, and winter to a bowl-shaped pattern in summer, indicating that thermal stratification intensified oxygen gradients. In addition, the majority of DO recovery occurred in the late afternoon during summer, suggesting that severe oxygen consumption delayed the daytime accumulation of DO. Our findings emphasize the critical roles of photosynthesis, respiration, and abiotic factors in shaping DO dynamics. This research enhances our understanding of DO fluctuations in eutrophic shallow lakes and provides valuable insights for ecosystem management, supporting the development of effective strategies to prevent and mitigate hypoxia. Full article

(This article belongs to the Special Issue Water Quality Monitoring and Prediction Using New Sensors, Machine Learning and Big Data)

► Show Figures

Figure 1

22 pages, 5100 KB

Open AccessArticle

Fe-Doped g-C₃N₄ for Enhanced Photocatalytic Degradation of Brilliant Blue Dye

by Rongjun Su, Haoran Liang, Hao Jiang, Guangshan Zhang and Chunyan Yang

Water 2025, 17(22), 3220; https://doi.org/10.3390/w17223220 - 11 Nov 2025

Abstract

Brilliant blue, as a pigment food additive, has all the characteristics of printing and dyeing wastewater and belongs to persistent and refractory organic compounds. The photocatalysis–Fenton reaction system consists of two parts: photocatalytic reaction and Fenton reaction. Electrons promote the decomposition of H [...] Read more.

Brilliant blue, as a pigment food additive, has all the characteristics of printing and dyeing wastewater and belongs to persistent and refractory organic compounds. The photocatalysis–Fenton reaction system consists of two parts: photocatalytic reaction and Fenton reaction. Electrons promote the decomposition of H₂O₂ to produce •OH. In addition, the effective separation of e- and h⁺ by light strengthens the direct oxidation of h⁺, and h⁺ reacts directly with OH⁻ to produce •OH, which can further promote the removal of organic pollutants. In this paper, g-C₃N₄ and Fe/g-C₃N₄ photocatalysts were prepared by the thermal polycondensation method. Fe/g-C₃N₄ of 15 wt% can reach 98.59% under the best degradation environment, and the degradation rate of g-C₃N₄ is only 7.6% under the same conditions. The photocatalytic activity of the catalysts was further studied. Through active species capture experiments, it is known that •OH and •O₂⁻ are the main active species in the system, and the action intensity of •OH is greater than that of •O₂⁻. The degradation reaction mechanism is that H₂O₂ combines with Fe²⁺ in Fe/g-C₃N₄ to generate a large amount of •OH and Fe³⁺, and the combination of Fe-N bonds accelerates the cycle of Fe³⁺/Fe²⁺ and promotes the formation of •OH, thereby accelerating the degradation of target pollutants. •O₂⁻ can reduce Fe³⁺ to Fe²⁺, Fe²⁺ reacts with H₂O₂ to produce •OH, which promotes degradation, and •O₂⁻ itself also plays a role in degradation. In addition, under the optimal experimental conditions obtained by response surface experiments, the fitting degree of first-order reaction kinetics is 0.96642, and the fitting degree of second-order reaction kinetics is 0.57884. Therefore, this reaction is more in line with first-order reaction kinetics. The adsorption rate is only proportional to the concentration of Fe/g-C₃N₄. Full article

(This article belongs to the Special Issue Advanced Oxidation Technologies for Water and Wastewater Treatment)

► Show Figures

Figure 1

17 pages, 442 KB

Open AccessArticle

The Effect of Irrigation and Vermicompost Applications on the Growth and Yield of Greenhouse Pepper Plants

by Sedat Boyacı, Atilgan Atilgan, Roman Rolbiecki and Joanna Kocięcka

Water 2025, 17(22), 3219; https://doi.org/10.3390/w17223219 - 11 Nov 2025

Abstract

In agricultural practice, improper irrigation levels and excessive fertiliser use negatively impact water resources and soil properties, respectively. This experiment aims to determine the effects of varying irrigation levels and vermicompost doses on the growth, quality, and productivity of pepper plants grown under [...] Read more.

In agricultural practice, improper irrigation levels and excessive fertiliser use negatively impact water resources and soil properties, respectively. This experiment aims to determine the effects of varying irrigation levels and vermicompost doses on the growth, quality, and productivity of pepper plants grown under polycarbonate greenhouse conditions. To achieve this objective, different irrigation levels (IL) of IL100 (100% full irrigation), IL75 (75%), IL50 (50%), and vermicompost doses (VD) of VD0 (0%), VD10 (10%), and VD20 (20%) were tested. The highest irrigation level was in the IL100–VD10 treatment, which also had the highest water consumption (ET) in the 27.8 L pot⁻¹. By comparison, the IL50–VD0 treatment had the lowest irrigation level in the 15.4 L pot⁻¹, representing nearly 55.4% of the maximum irrigation water amount. The findings showed that the irrigation levels and vermicompost doses had a significant impact on plant growth, quality, and fruit yield parameters. Accordingly, the irrigation levels and vermicompost doses had significant effects on the studied plant growth parameters (stem diameter, plant height, number of leaves, stem fresh weight, stem dry weight, root fresh weight, and root dry weight). Similar effects were also observed on the fruit quality parameters (fruit width, fruit length, fruit weight, fruit flesh thickness, pH, titratable acidity (TA), total soluble solids (TSS), chrome, and hue). This study found that the highest total yield (164.5 g pot⁻¹), marketable yield (149.8 g pot⁻¹), total water use efficiency (6.1 g L⁻¹), and marketable water use efficiency (5.6 g L⁻¹) were obtained at the 100% irrigation level. However, similar results were observed at the 75% irrigation level and a 20% vermicompost dose, where the total water use efficiency was 5.9 g L⁻¹ and the marketable water use efficiency was 5.3 g L⁻¹. This suggests that 75% irrigation can be a viable alternative to full irrigation (100%) and offers water-saving potential, particularly in areas with limited water resources. Full article

(This article belongs to the Special Issue Soil Water Use and Irrigation Management, 2nd Edition)

► Show Figures

Figure 1

22 pages, 6888 KB

Open AccessArticle

Research on the Disaster-Causing Factors of Water and Sand Inrush and the Evolution of Surface Collapse Funnel

by Rongqiang Wang, Binghan Lv, Qirui Yang and Guibin Zhang

Water 2025, 17(22), 3218; https://doi.org/10.3390/w17223218 - 11 Nov 2025

Abstract

Water and sand inrush is frequently accompanied by surface subsidence, which severely constrains the sustainable development of coordinated coal mining and ecological environment. This study investigated four key influencing factors based on a water and sand inrush test system: fracture width, aquifer thickness, [...] Read more.

Water and sand inrush is frequently accompanied by surface subsidence, which severely constrains the sustainable development of coordinated coal mining and ecological environment. This study investigated four key influencing factors based on a water and sand inrush test system: fracture width, aquifer thickness, sand particle size composition and stratigraphic sedimentary structure. It obtained the morphological evolution characteristics of collapse funnels and revealed the evolution mechanism of collapse funnels induced by water and sand inrush. The results indicate that fracture width and aquifer thickness mainly affect the range of collapse funnel, and both show a positive correlation with the radius of collapse funnels. Sandy particle size composition plays a dominant role in the morphology of collapse funnels induced by disasters: as the size of the soil skeleton particles increases, the morphology of collapse funnels changes sequentially from a bowl shape to an inverted cone shape and then to a funnel shape with a sunken center and raised slopes. The stratigraphic sedimentary structure has a significant impact on the morphology and damage induced by disasters in collapse funnels. The upper clay layer of the underlying aquifer inhibits the water and sand inrush processes to some extent. An increase in the thickness and number of clay layers effectively prevents the water and sand mixture from flowing into the fracture channel from the lateral direction. This reduces the damage range of collapse funnels and decreases the rate of water and sand inrush. This study clarifies the formation mechanism of surface collapse funnels under the influence of the disaster-causing factors of water and sand inrush, and provides theoretical guidance for the prevention and control of such disasters. Full article

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

► Show Figures

Figure 1

26 pages, 2520 KB

Open AccessArticle

Research on Arch Dam Deformation Safety Early Warning Method Based on Effect Separation of Regional Environmental Variables and Knowledge-Driven Approach

by Jianxue Wang, Fei Tong, Zhiwei Gao, Lin Cheng and Shuaiyin Zhao

Water 2025, 17(22), 3217; https://doi.org/10.3390/w17223217 - 11 Nov 2025

Abstract

There are significant differences in the deformation patterns of different parts of arch dams, and there is a common situation of periodic data loss. To accurately analyze the deformation behavior of arch dams, this paper proposes a safety warning and anomaly diagnosis method [...] Read more.

There are significant differences in the deformation patterns of different parts of arch dams, and there is a common situation of periodic data loss. To accurately analyze the deformation behavior of arch dams, this paper proposes a safety warning and anomaly diagnosis method for arch dam deformation based on the separation of environmental variable effects in different partitions and a knowledge-driven approach. This method combines various techniques such as an optimized ISODATA clustering method, probabilistic principal component analysis (PPCA), square prediction error (SPE) norm control chart, and contribution chart. By defining data forms and rules, existing engineering specifications and experience are transformed into “knowledge” and applied to the operation and management of arch dams, achieving accurate monitoring of arch dam deformation status and timely diagnosis of outliers. Through monitoring data verification of horizontal displacement in a certain arch dam partition, the results show that this method can accurately identify deformation anomalies in the arch dam and effectively separate the influence of environmental variables and noise interference, providing strong support for the safe operation of the arch dam. Accurate deformation monitoring of arch dams is essential for ensuring structural safety and optimizing operational management. However, conventional early warning indicators and empirical models often fail to capture the spatial heterogeneity of deformation and the complex coupling between environmental variables and structural responses. To overcome these limitations, this study proposes a knowledge-driven safety early warning and anomaly diagnosis model for arch dam deformation, based on spatiotemporal clustering and partitioned environmental variable separation. The method integrates the optimized ISODATA clustering algorithm, probabilistic principal component analysis (PPCA), squared prediction error (SPE) control chart, and contribution chart to establish a comprehensive monitoring framework. The optimized ISODATA identifies deformation zones with similar mechanical behavior, PPCA separates environmental influences such as temperature and reservoir level from structural responses, and the SPE and contribution charts quantify abnormal variations and locate potential risk regions. Application of the proposed method to long-term deformation monitoring data demonstrates that the PPCA-based framework effectively separates environmental effects, improves the interpretability of zoned deformation characteristics, and enhances the accuracy and reliability of anomaly identification compared with conventional approaches. These findings indicate that the proposed knowledge-driven model provides a robust and interpretable framework for precise deformation safety evaluation of arch dams. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Hydraulic Engineering, 2nd Edition)

13 pages, 9923 KB

Open AccessArticle

Analysis of Hydrodynamic Behavior of the Floating Tapered Trash Intercepting Net in Currents

by Gangjie Yu, Zhenzhou Sun, Zhendong Lin, Tiaojian Xu and Mingxiao Xie

Water 2025, 17(22), 3216; https://doi.org/10.3390/w17223216 - 11 Nov 2025

Abstract

Ensuring the structural reliability and interception efficiency of trash-intercepting nets (TINs) is crucial for the security of the water withdrawal engineering of the nuclear power station (NPS). The numerical model of a flexible TIN using the lumped mass method was developed, and its [...] Read more.

Ensuring the structural reliability and interception efficiency of trash-intercepting nets (TINs) is crucial for the security of the water withdrawal engineering of the nuclear power station (NPS). The numerical model of a flexible TIN using the lumped mass method was developed, and its high accuracy in simulating the tension distribution of the net and its deformation was validated through physical model tests. A systematic analysis was performed to investigate the effect of key parameters (i.e., water depth, intercepting rate, and diameter of longitudinal/transversal ropes) on the structural response, including the total anchor force, the main cable tension, the rope tension, and the netting tension. The results show that the tension forces acting on the transversal ropes are dramatically larger than those acting on the longitudinal ropes, and the net experiences the smallest tension force when the diameter of transversal ropes is the same as the diameter of the longitudinal ropes. This study is useful for the safety design of the TIN of the NPS. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

► Show Figures

Figure 1

Journal Description

Water

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Further Information

Guidelines

MDPI Initiatives

Follow MDPI