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Water, Volume 17, Issue 3 (February-1 2025) – 176 articles

Cover Story (view full-size image): Extreme climatic events have become more frequent in recent decades and are affecting freshwater ecosystems globally. The focus of this research is the bloom-forming potential of the harmful, originally tropical, Raphidiopsis (Cylindrospermopsis) raciborskii cyanobacterium in a temperate floodplain lake. The cyclical occurrence of extreme floods (2006 and 2013) and extreme droughts (2003 and 2015) in the Danube River Basin promoted ecological disturbances in the stable states of the lake between clear and turbid phytoplankton conditions. Despite extreme summer drought triggering the bloom, the observed declining trend in total cyanobacterial biomass, including the less frequent occurrence of the R. raciborskii bloom, suggests that the effects of climate change may be less detrimental in preserved floodplain ecosystems. View this paper
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16 pages, 6807 KiB  
Article
Accuracy Evaluation of Multiple Runoff Products: A Case Study of the Middle Reaches of the Yellow River
by Handi Cui and Chang Huang
Water 2025, 17(3), 461; https://doi.org/10.3390/w17030461 - 6 Feb 2025
Abstract
Recent advances in hydrological modling have led to the generation of numerous global or regional runoff datasets, which have been widely used in hydrological analysis. However, it is not yet clear how their accuracy and reliabilities are. In this study, using observed gauge [...] Read more.
Recent advances in hydrological modling have led to the generation of numerous global or regional runoff datasets, which have been widely used in hydrological analysis. However, it is not yet clear how their accuracy and reliabilities are. In this study, using observed gauge streamflow data at four stations (Hequ, Fugu, Wubu, and Longmen) in the middle reaches of the Yellow River as reference, we compare and evaluate the accuracy of three runoff gridded dataset products (GloFAS, GRFR v1.0, and WGHM) at four temporal scales: daily, monthly, annual, and wet/dry seasons. The results indicate the following: (1) As the temporal scale increases, the simulated streamflow accuracy of the three datasets gradually improves. The GloFAS dataset performs the best at daily scale, while the WGHM dataset outperforms the other two at monthly and annual scales. (2) The three datasets all tend to overestimate the total streamflow at the main stations. (3) Comparing the two hydrological scenarios of wet and dry seasons, all three datasets exhibit better performance during the wet season. (4) The capture of peak streamflow is influenced by dataset type, temporal scale, and station characteristics. In general, the three datasets perform better at stations with higher base streamflow, such as Longmen and Wubu stations. Additionally, this study discusses the possible reasons for their different performances, which can be mainly attributed to three aspects: the quality of meteorological input datasets, missing or simplified simulation processes, and incorrect model structure and parameterization. Future research will consider revising the datasets to obtain more accurate data sources and further enhance the accuracy of watershed streamflow simulations. Full article
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19 pages, 19551 KiB  
Article
A Novel Monthly Runoff Prediction Model Based on KVMD and KTCN-LSTM-SA
by Shujian Zhang, Kui Zhu and Chaohe Wang
Water 2025, 17(3), 460; https://doi.org/10.3390/w17030460 - 6 Feb 2025
Abstract
Due to the uncertainty of meteorological factors and the influence of human activities, the monthly runoff series often exhibit the characteristics of non-stationarity. The appropriate prediction model and the hyperparameters of the model are often difficult to determine, and this affects the model [...] Read more.
Due to the uncertainty of meteorological factors and the influence of human activities, the monthly runoff series often exhibit the characteristics of non-stationarity. The appropriate prediction model and the hyperparameters of the model are often difficult to determine, and this affects the model prediction performance. For obtaining the accurate runoff prediction results, a novel prediction model (KVMD-KTCN-LSTM-SA) is proposed. This hybrid model uses Kepler optimization algorithm (KOA)-optimized Variable Mode Decomposition (KVMD), KOA-optimized temporal convolutional network–long short-term memory (TCN-LSTM), and the self-attention (SA) mechanism. KVMD effectively reduces the difficulty of predicting the monthly runoff series, KOA helps to find the optimal hyperparameters of the model, TCN is combined with LSTM, and the SA mechanism effectively increases the performance of the model. Monthly runoff from three hydrological stations in the Hetian River basin and one hydrological station in the Huaihe River basin are predicted with the proposed model, and six models are selected for comparison. The KVMD-KTCN-LSTM-SA model effectively reduces runoff fluctuation and combines the advantages of multiple models and achieves satisfactory runoff prediction results. During the testing period, the proposed model achieves NSE of 0.978 and R2 of 0.982 at Wuluwati station, NSE of 0.975 and R2 of 0.986 at Tongguziluoke station, and NSE of 0.978 and R2 of 0.982 at Jiangjiaji station. The proposed hybrid model provides a new approach for monthly runoff prediction, which is capable of better managing and predicting mid-long-term runoff. Full article
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21 pages, 3551 KiB  
Article
Biodeterioration Study of Cementitious Materials During Sewage Treatment Processes
by Nedson T. Kashaija, Viktória Gável, Gabriel Iklaga, Augustina Alexander, Krett Gergely, Tamás Mireisz, Csaba Szabó, Zsuzsanna Szabó-Krausz, Márta Vargha and Erika Tóth
Water 2025, 17(3), 459; https://doi.org/10.3390/w17030459 - 6 Feb 2025
Abstract
The relationship between microbial communities and mineralogical/mechanical changes was studied regarding the biodeterioration of Portland cement (PC) and calcium sulfoaluminate cement (CSAC) in a wastewater treatment plant. An in situ experiment was conducted by submerging 12 independent PC and CSAC specimens in a [...] Read more.
The relationship between microbial communities and mineralogical/mechanical changes was studied regarding the biodeterioration of Portland cement (PC) and calcium sulfoaluminate cement (CSAC) in a wastewater treatment plant. An in situ experiment was conducted by submerging 12 independent PC and CSAC specimens in a sand-trap structure for 10, 30, 75, 150, and 240 days. The microbiological analyses of the 16S rRNA genes of bacteria and Archaea from the biofilms and the geochemical analysis were performed on the studied specimens. The results showed that while there were characteristic changes in PC specimens over time, CSAC specimens showed few biodeterioration effects. The dominant bacteria identified from the biofilms of specimens belonged to the classes of Gammaproteobacteria (8.4–32.4%), Bacilli (1.6–21.6%), Clostridia (4–15.4%), Bacteroidia (2–18.8%), Desulfovibronia (0.5–19%), Campylobacteria (0.4–26.8%), and Actinobacteria (1.8–12.8%). The overall relative abundance of the bacteria linked to biodeterioration processes increased to more than 50% of the total bacterial communities after 75 days of sewage exposure and was found to be strongly correlated with several PC deterioration parameters (e.g., mass loss, calcite and ettringite minerals), whereas no significant correlation was revealed between these genera and CSAC characteristics. Full article
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25 pages, 12303 KiB  
Article
Soil and Water Assessment Tool-Based Prediction of Runoff Under Scenarios of Land Use/Land Cover and Climate Change Across Indian Agro-Climatic Zones: Implications for Sustainable Development Goals
by Saravanan Subbarayan, Youssef M. Youssef, Leelambar Singh, Dominika Dąbrowska, Nassir Alarifi, RAAJ Ramsankaran, R. Visweshwaran and Ahmed M. Saqr
Water 2025, 17(3), 458; https://doi.org/10.3390/w17030458 - 6 Feb 2025
Abstract
Assessing runoff under changing land use/land cover (LULC) and climatic conditions is crucial for achieving effective and sustainable water resource management on a global scale. In this study, the focus was on runoff predictions across three diverse Indian watersheds—Wunna, Bharathapuzha, and Mahanadi—spanning distinct [...] Read more.
Assessing runoff under changing land use/land cover (LULC) and climatic conditions is crucial for achieving effective and sustainable water resource management on a global scale. In this study, the focus was on runoff predictions across three diverse Indian watersheds—Wunna, Bharathapuzha, and Mahanadi—spanning distinct agro-climatic zones to capture varying climatic and hydrological complexities. The soil and water assessment (SWAT) tool was used to simulate future runoff influenced by LULC and climate change and to explore the related sustainability implications, including related challenges and proposing countermeasures through a sustainable action plan (SAP). The methodology integrated high-resolution satellite imagery, the cellular automata (CA)–Markov model for projecting LULC changes, and downscaled climate data under representative concentration pathways (RCPs) 4.5 and 8.5, representing moderate and extreme climate scenarios, respectively. SWAT model calibration and validation demonstrated reliable predictive accuracy, with the coefficient of determination values (R2) > 0.50 confirming the reliability of the SWAT model in simulating hydrological processes. The results indicated significant increases in surface runoff due to urbanization, reaching >1000 mm, 600 mm, and 400 mm in southern Bharathapuzha, southeastern Wunna, and northwestern Mahanadi, respectively, especially by 2040 under RCP 8.5. These findings indicate that water quality, agricultural productivity, and urban infrastructure may be threatened. The proposed SAP includes nature-based solutions, like wetland restoration, and climate-resilient strategies to mitigate adverse effects and partially achieve sustainable development goals (SDGs) related to clean water and climate action. This research provides a robust framework for sustainable watershed management in similar regions worldwide. Full article
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23 pages, 7106 KiB  
Article
Spatiotemporal Variations and Influencing Factors of Arid Inland Runoff in the Shule River Basin, Northwest China
by Wenrui Zhang, Dongyuan Sun, Zuirong Niu, Yike Wang, Heping Shu, Xingfan Wang and Yanqiang Cui
Water 2025, 17(3), 457; https://doi.org/10.3390/w17030457 - 6 Feb 2025
Abstract
Considering the possibility of increasing water supply in China in the short term and the long-term threat posed by shrinking glaciers, this paper studied the spatiotemporal evolution of runoff in typical arid areas and the influence of hydrometeorological elements on runoff, aiming to [...] Read more.
Considering the possibility of increasing water supply in China in the short term and the long-term threat posed by shrinking glaciers, this paper studied the spatiotemporal evolution of runoff in typical arid areas and the influence of hydrometeorological elements on runoff, aiming to clarify the hydrological cycle law and provide a basis for adjusting water resource management strategies to cope with future uncertain changes. Based on hydrological data from 1956 to 2020, the spatial and temporal variation in runoff were discussed by means of wavelet analysis, MK test, RS analysis, and spatial interpolation. The influencing factors of runoff evolution in the Shule River Basin were determined. The results showed that the runoff in the Shule River Basin showed an increasing trend in the past 60 years. Five hydrological stations (Changmabao Station, Panjiazhuang Station, Shuangtabao Reservoir, Dangchengwan Reservoir, and Danghe Reservoir) were selected as the research objects. Among them, the runoff of Changmabao Station increased the most, which was 1.202 × 108 m3/10 a. Future projections suggest a continued rise in runoff, particularly at Shuangtabao Reservoir. The runoff exhibited positive persistence and varying degrees of mutation, with most mutations occurring in the early 21st century. The runoff in the basin has a periodicity of multiple time scales (there are 2–3 main cycles), and the main cycle of annual runoff is concentrated in 58 years. This comprehensive analysis provides valuable insights for the sustainable management of water resources in inland river basins amidst changing environmental conditions. The spatial variation in runoff in summer and autumn and the whole year showed a significant southeast to northwest decreasing pattern. During the study period, accelerated glacier melting caused by rising temperatures had the most significant impact on runoff change (p < 0.01), and the upstream of the study area also complied with this rule (temperature contribution rate [25.96%] > precipitation contribution rate [23.91%]). The contribution of temperature and precipitation changes caused by human activities in the middle stream to runoff was relatively large, which showed that the contribution rate of temperature in Guazhou Station to runoff was 34.23% and the contribution rate of precipitation in Dangchengwan to runoff was 60.27%. The research results provide a scientific basis for the rational and efficient utilization of water resources in the arid area of Northwest China. Full article
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23 pages, 12559 KiB  
Article
Research on Flow Field Characteristics of a Three-Plate Vertical Rotary Gate
by Houyi Qi, Xiao Zhang, Yuxue Sun, Xinyu Ji, Dong Tian, Chao Sun, Zhenzhen Xue and Yanshun Liu
Water 2025, 17(3), 456; https://doi.org/10.3390/w17030456 - 6 Feb 2025
Abstract
Steady-state and transient hydraulic characteristics of a novel three-plate vertical rotary gate were analysed through physical model experiments and numerical simulations. An experimental gate system was built to analyse the flow characteristics of the gate, and a steady-state flow prediction model was proposed. [...] Read more.
Steady-state and transient hydraulic characteristics of a novel three-plate vertical rotary gate were analysed through physical model experiments and numerical simulations. An experimental gate system was built to analyse the flow characteristics of the gate, and a steady-state flow prediction model was proposed. Steady-state numerical simulations of the gate were conducted to analyse flow field distribution characteristics. A transient numerical model of the gate was established to analyse the flow field distribution characteristics during opening and closing. The discharge coefficient evolution law under different speed conditions was revealed. Under various water levels, the steady-state discharge coefficient of the gate was similar. Within a 0–90° opening, the discharge coefficient grew exponentially. A steady-state flow prediction model for the gate revealed a prediction error of <7%. The discharge coefficient of the gate increased with decreasing opening speed; when the gate was closed, it exhibited asymmetric variation characteristics. The flow hysteresis effect was more evident at higher speeds. Plate 2 experienced the maximum flow force. In the transient state, the flow force acting on the plates exhibited a periodic fluctuation pattern, and the maximum flow force increased with the gate speed. A reference for the design and application of fast opening and closing gates is provided. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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16 pages, 662 KiB  
Article
Effectiveness of Voluntary Nutrient Management Measures to Reduce Nitrate Leaching on Dairy Farms Using Soil N Surplus as an Indicator
by J. Verloop, C. van den Brink and J. Gielen
Water 2025, 17(3), 455; https://doi.org/10.3390/w17030455 - 6 Feb 2025
Abstract
A pilot study with 18 dairy farms in recharge areas of five vulnerable drinking water abstractions in the Dutch province of Overijssel aimed to reduce nitrate leaching risks to the upper meter of groundwater through improved farm management. The pilot employed a voluntary, [...] Read more.
A pilot study with 18 dairy farms in recharge areas of five vulnerable drinking water abstractions in the Dutch province of Overijssel aimed to reduce nitrate leaching risks to the upper meter of groundwater through improved farm management. The pilot employed a voluntary, mutual gain approach, promoting measures that enhanced both nutrient efficiency and groundwater quality. Over the research period (2011–2017), nitrogen surpluses on the soil balance declined significantly from 153 to 96 kg N per ha per year, achieving the target of 100 kg N per ha per year. Despite this decline, average nitrate concentrations in the upper meter of groundwater fluctuated annually, showing no significant reduction in grassland but a noticeable decrease in maize. Economic evaluation showed that relative fodder profitability (RFP) increased over time, suggesting positive financial effects of implemented measures, as acknowledged by participating farmers. However, the adoption of measures perceived as complex or less financially rewarding remained limited, highlighting the challenges of relying solely on voluntary implementation. The absence of farm-specific feedback on nitrate leaching emerged as a critical limitation, emphasizing the need for additional monitoring tools, such as residual soil nitrogen assessments, to provide actionable insights at the farm or field level. These findings underscore the potential for further reducing nitrate leaching through enhanced feedback systems, precise execution of measures, and collaborative efforts integrating farmer expertise and scientific knowledge. Full article
(This article belongs to the Topic Human Impact on Groundwater Environment, 2nd Edition)
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48 pages, 9639 KiB  
Review
Clean and Green Bamboo Magic: Recent Advances in Heavy Metal Removal from Water by Bamboo Adsorbents
by Monika Negi, Vinju Thankachan, Arya Rajeev, M. Vairamuthu, S. Arundhathi and P. V. Nidheesh
Water 2025, 17(3), 454; https://doi.org/10.3390/w17030454 - 6 Feb 2025
Abstract
Adsorbents derived from bamboo, such as biochar, charcoal, activated carbon, and chemically modified bamboo, are recognized for their efficiency and cost-effectiveness in removing heavy metals from water. Despite this, there remains a gap in applying bamboo-based adsorbents for treating heavy metal-contaminated water sources, [...] Read more.
Adsorbents derived from bamboo, such as biochar, charcoal, activated carbon, and chemically modified bamboo, are recognized for their efficiency and cost-effectiveness in removing heavy metals from water. Despite this, there remains a gap in applying bamboo-based adsorbents for treating heavy metal-contaminated water sources, particularly regarding their physicochemical properties, adsorption mechanisms, and modifications. This review highlights the influence of factors such as specific surface area, pore distribution, pH, cation exchange capacity, elemental composition, and surface functional groups on the ability of bamboo adsorbents to adsorb heavy metals. It also discusses recent advancements in enhancing the properties of bamboo adsorbents through physical and chemical modifications and examines how variables like adsorbent dosage, water pH, temperature, initial concentrations of cations, and heavy metals affect heavy metal removal. The review categorizes the mechanisms of heavy metal adsorption into surface complexation, physical adsorption, electrostatic interaction, ion exchange, precipitation, and redox effect. While bamboo-based adsorbents have shown higher sorption capacity in laboratory settings, there is a need for more comprehensive studies to optimize their performance, scalability, and cost-effectiveness in real-world applications. Full article
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17 pages, 4861 KiB  
Article
Water Quality Assessment and Forecasting Along the Liffey and Andarax Rivers by Artificial Neural Network Techniques Toward Sustainable Water Resources Management
by Eyad Abushandi
Water 2025, 17(3), 453; https://doi.org/10.3390/w17030453 - 6 Feb 2025
Abstract
This research evaluates water quality in two contrasting hydro-climatic regions: the River Liffey in Ireland and the Andarax River in Spain. It utilizes an Artificial Neural Network (ANN) to simulate potential changes in key water-quality parameters based on field measurements. The ANN models [...] Read more.
This research evaluates water quality in two contrasting hydro-climatic regions: the River Liffey in Ireland and the Andarax River in Spain. It utilizes an Artificial Neural Network (ANN) to simulate potential changes in key water-quality parameters based on field measurements. The ANN models showed strong predictive efficiency and performance, achieving R2 values of 0.89 for dissolved oxygen (DO), 0.98 for electrical conductivity (EC), 0.87 for pH, 0.95 for total dissolved solids (TDS), and 0.96 for turbidity. The root mean-square-error (RMSE) values for important parameters were DO (1.25 mg/L), EC (48.06 µS/cm), and turbidity (8.9 FNU). The models were able to capture complex nonlinear relationships under different environmental conditions. The results showed that DO levels in the Liffey will decline by up to 20% over the next decade due to rising nutrient pollution, while TDS levels in the Andarax River are expected to rise by approximately 15% during the same period as a result of ongoing agricultural runoff. The study also simulated potential future hypothetical scenarios by applying the model to four different “what-if” situations. Overall, the research underscores the significance of machine learning in understanding intricate water-quality dynamics. Full article
(This article belongs to the Special Issue Research Progress on Water Quality and Sediment Quality)
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17 pages, 3642 KiB  
Article
Environmental DNA Metabarcoding as a Promising Conservation Tool for Monitoring Fish Diversity in Dongshan Bay, China
by Yanxu Zhang, Weiyi He, Lei Wang, Danyun Ou, Jinli Qiu, Weiwen Li and Hao Huang
Water 2025, 17(3), 452; https://doi.org/10.3390/w17030452 - 6 Feb 2025
Abstract
Dongshan Bay is a typical subtropical semi-enclosed bay characterized by abundant fish resources. We aimed to assess fish diversity and its seasonal variation in Dongshan Bay and to provide a scientific basis for the sustainable management and conservation of the fishery’s resources. In [...] Read more.
Dongshan Bay is a typical subtropical semi-enclosed bay characterized by abundant fish resources. We aimed to assess fish diversity and its seasonal variation in Dongshan Bay and to provide a scientific basis for the sustainable management and conservation of the fishery’s resources. In this study, we employed environmental DNA (eDNA) metabarcoding technology to analyze fish diversity in the bay during winter 2023 and summer 2024. A total of 76 fish species were detected across 12 sampling sites, with 43 species identified in summer and 45 species seen in winter. Overall, 13 species were detected in both the winter and summer. Non-significant differences were observed in Alpha diversity among the sampling sites. Fish species richness at the HXH2 site was the lowest among all the sampling sites for the reason that this sampling site was near to the effluent outlet of the Zhangzhou nuclear power plant and notably influenced by the thermal discharge. In general, fish diversity and abundance were higher in winter than in summer. RDA test analysis revealed that water temperature and dissolved oxygen were the primary environmental factors influencing fish distribution in summer. In winter, the influence of various factors is relatively balanced, with chlorophyll and Blue Green Algae Phycoerythrin (BGA PE) having a relatively greater impact than other factors. Our results offer valuable insights into enhancing fish diversity management in Dongshan Bay. Full article
(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)
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22 pages, 6361 KiB  
Article
An Analysis of the Current Situation of Ecological Flow Release from Large- and Medium-Sized Reservoirs in the Southeastern River Basins of China
by Yijing Chen, Hui Nie, Gaozhan Liu, Jiongling Xiao, He Qiu, Bingjiao Xu, Hao Chen, Saihua Huang and Huawei Xie
Water 2025, 17(3), 451; https://doi.org/10.3390/w17030451 - 6 Feb 2025
Abstract
Ecological flow is a crucial determinant of river ecosystem well-being and aquatic ecosystem stability. Large- and medium-sized reservoirs, with flood prevention, irrigation, and power generation functions, necessitate a scientifically devised ecological flow release plan for river ecosystem conservation and water quality amelioration. This [...] Read more.
Ecological flow is a crucial determinant of river ecosystem well-being and aquatic ecosystem stability. Large- and medium-sized reservoirs, with flood prevention, irrigation, and power generation functions, necessitate a scientifically devised ecological flow release plan for river ecosystem conservation and water quality amelioration. This study centered on three reservoirs in the Jiaojiang River Basin of Zhejiang Province, China. Using measured outflow data, the hydrological approach was initially adopted to calculate individual reservoir ecological flows. Subsequently, the entropy weight method was employed to ascertain the most suitable ecological flow. Ecological flow grade thresholds were then established to formulate the optimal release scheme. The outcomes demonstrated that the average ecological flows of Xia’an, Lishimen, and Longxi reservoirs were 1.90 m3/s, 1.95 m3/s, and 0.42 m3/s, respectively. The multi-year average ecological flow assurance rates were 62.53%, 77.72%, and 56.94%, successively. The entropy weighted downstream optimal ecological flows were 2.10 m3/s, 2.28 m3/s, and 0.44 m3/s. During periods when the monthly ecological flow assurance rate was below 60%, the three reservoirs implemented schemes of installing ecological siphons, renovating water diversion systems, and using post-dam ecological units, respectively. Full article
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13 pages, 21260 KiB  
Article
Parametric vs. Non-Parametric Approach for the Estimation of the SPI Drought Index
by Harris Vangelis and Ioannis M. Kourtis
Water 2025, 17(3), 450; https://doi.org/10.3390/w17030450 - 6 Feb 2025
Abstract
Accurate drought identification is important for both scientists and decision-makers to be able to make informative decisions. In this study, parametric and non-parametric approaches for analyzing meteorological drought are compared, aiming at simplifying the calculation of the Standardized Precipitation Index (SPI). The comparison [...] Read more.
Accurate drought identification is important for both scientists and decision-makers to be able to make informative decisions. In this study, parametric and non-parametric approaches for analyzing meteorological drought are compared, aiming at simplifying the calculation of the Standardized Precipitation Index (SPI). The comparison is performed across various meteorological stations covering the entire territory of Greece, using monthly rainfall data spanning from 1961 to 2021. Meteorological drought is assessed through the SPI for the 12-month reference period. A two-parameter gamma distribution, with parameters estimated using the maximum likelihood estimation method, is employed for the estimation of the SPI drought index as the parametric classic approach. For the non-parametric approach, the SPI drought index is estimated using six empirical probability plotting positions: Beard, Blom, Cunnane, Gringorten, Hazen, and Weibull. Results indicate that the empirical approach can effectively identify drought events in comparison to the classic approach. However, caution is advised, particularly when different drought classes are identified, as the non-parametric approaches may underestimate drought severity. In addition, for the Greek meteorological conditions, the results revealed that in the case of extreme drought events, the estimation of SPI employing the classic approach is to be preferred. Full article
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5 pages, 2747 KiB  
Editorial
Evolution Mechanisms and Mitigation of Soil Erosion
by Chengcheng Xia and Jian Luo
Water 2025, 17(3), 449; https://doi.org/10.3390/w17030449 - 6 Feb 2025
Abstract
This Editorial paper summarizes the Special Issue entitled “Evolution of Soil and Water Erosion” in Water. This Special Issue aims to collect new knowledge on and advances in the evolution of soil and water erosion and its complex interplay with natural and human-induced [...] Read more.
This Editorial paper summarizes the Special Issue entitled “Evolution of Soil and Water Erosion” in Water. This Special Issue aims to collect new knowledge on and advances in the evolution of soil and water erosion and its complex interplay with natural and human-induced factors. Five high-quality papers have been published in the Special Issue, which mainly covers new insights into the themes of erosion mechanisms and environmental drivers, erosion control and mitigation strategies and the relationship between hydraulic parameters and erosion. Overall, these studies have broadened the understanding of soil erosion and soil and water conservation, emphasizing the importance of research in this field for environmental sustainability. In future research, interdisciplinary integration into theory and methodology will play a crucial role in breakthroughs in the understanding of soil erosion and innovations in prevention and control technologies. Full article
(This article belongs to the Special Issue Evolution of Soil and Water Erosion)
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16 pages, 6923 KiB  
Article
Study on the Erosion Damage Law in Mountain Flood Disasters Regarding the Exposed Section of Oil Pipelines
by Xiaofei Jing, Jingxin Mao, Jian Ou, Xiaohua Liu, Yuanzhen Zhang and Dongsong Chen
Water 2025, 17(3), 448; https://doi.org/10.3390/w17030448 - 5 Feb 2025
Abstract
Oil pipelines are susceptible to significant hydraulic erosion from mountain torrents during the flood season when passing through the mountain valley area, which can lead to soil erosion on the pipe surface and expose the pipeline. Accordingly, this study centers on investigating the [...] Read more.
Oil pipelines are susceptible to significant hydraulic erosion from mountain torrents during the flood season when passing through the mountain valley area, which can lead to soil erosion on the pipe surface and expose the pipeline. Accordingly, this study centers on investigating the critical issue of the failure mechanism caused by flash flood erosion in the exposed section of oil pipelines. Both indoor testing and numerical simulation research methods are employed to analyze the flow field distribution characteristics of flash floods in proximity to an exposed pipeline. This study explores the patterns of soil loss around pipelines of varying pipe diameters, levels of exposure, and pipe flow angles. In addition, the spatial and temporal evolution mechanism of pipelines overhang development under the action of flash floods was elucidated. The experimental observations indicate that as the pipe diameter increases, the failure rate of the soil surrounding the pipe accelerates, while the erosion effect on the soil around the executives becomes more pronounced. Additionally, a larger pipe flow angle leads to a reduced soil loss in the downstream direction of the pipe. During flash flood events, the scouring action on the soil surrounding the pipe leads to rapid compression of the flow field around the pipe, while the vortex at the pipe’s bottom exacerbates soil corrosion. Additionally, the maximum pressure exerted on pipeline surfaces at pipeline flow angles of 30°, 60°, and 90° is 14,382 Pa, 16,146 Pa, and 17,974 Pa, respectively. The research results offer valuable insights into pipeline, soil, and water conservation projects in mountain valley regions. Full article
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17 pages, 4574 KiB  
Article
A Hydraulic Turbine Fault Diagnosis Method Based on Synchrosqueezed Wavelet Transform and SE-ResNet
by Ye Liu, Yanhe Xu, Jie Liu and Xinqiang Niu
Water 2025, 17(3), 447; https://doi.org/10.3390/w17030447 - 5 Feb 2025
Abstract
To tackle the challenges associated with conventional methods of diagnosing hydraulic turbine faults, which depend heavily on expert knowledge and exhibit low efficiency and precision, a model for detecting hydraulic turbine faults has been developed that integrates the synchrosqueezed wavelet transform (SWT) with [...] Read more.
To tackle the challenges associated with conventional methods of diagnosing hydraulic turbine faults, which depend heavily on expert knowledge and exhibit low efficiency and precision, a model for detecting hydraulic turbine faults has been developed that integrates the synchrosqueezed wavelet transform (SWT) with SE-ResNet. Initially, a 1D non-stationary vibration signal is converted into a high-frequency time–frequency representation in two dimensions using SWT, which then acts as the input for the convolutional neural network. Secondly, a model based on SE-ResNet is designed, incorporating an attention mechanism that enhances the extraction of features from two-dimensional images, thereby increasing the emphasis on crucial features and bolstering the model’s representation capabilities. Finally, results related to fault detection are produced via the softmax layer. To evaluate the proposed model’s efficiency, two datasets were utilized for the experiments conducted, one sourced from Case Western Reserve University and the other from hydraulic turbine vibration signals. Compared to conventional approaches, this technique demonstrates significant practicality and effective convergence characteristics, offering considerable value in real-world applications. Full article
(This article belongs to the Special Issue Research Status of Operation and Management of Hydropower Station)
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16 pages, 17053 KiB  
Article
Adding to Our Knowledge on the Diatom and Green Algae Biodiversity of Egypt: Some New-to-Science, Poorly Known, and Newly Recorded Species
by Abdullah A. Saber, Mostafa M. El-Sheekh, Olfat M. A. Salem, Zlatko Levkov, Marco Cantonati, Modhi O. Alotaibi and Hani Saber
Water 2025, 17(3), 446; https://doi.org/10.3390/w17030446 - 5 Feb 2025
Abstract
During our research on the diversity of diatoms and green microalgae from Egypt, four new-to-science, newly recorded, and poorly known species were retrieved from different Egyptian habitats. The new benthic diatom species Halamphora shaabanii A.A. Saber, El-Sheekh, Levkov, H. Saber et Cantonati sp. [...] Read more.
During our research on the diversity of diatoms and green microalgae from Egypt, four new-to-science, newly recorded, and poorly known species were retrieved from different Egyptian habitats. The new benthic diatom species Halamphora shaabanii A.A. Saber, El-Sheekh, Levkov, H. Saber et Cantonati sp. nov., which could not be identified using the currently available literature, was described from the high-conductivity, oasis lake Abu Nuss in the El-Farafra Oasis, located in the Western Desert of Egypt, employing both light (LM) and scanning electron (SEM) microscopy observations. A detailed comparison of the biometrically distinctive traits, and ecological preferences, of this new diatom species revealed sufficient differentiations from its morphologically most closely related species: H. atacamana, H. caribaea, H. ectorii, H. gasseae, H. halophila, H. mosensis, H. poianensis, and H. vantushpaensis. Ecologically, Halamphora shaabanii can tolerate relatively high nutrients (N and P) and prefers saline inland environments with NaCl water types. The araphid diatom Pseudostaurosiropsis geocollegarum was observed in the epilithic diatom assemblages of the River Nile Damietta Branch and identified on the basis of LM and SEM. From an ecological standpoint, P. geocollegarum seems to prefer elevated nutrient concentrations (meso-eutraphentic species), reflecting different human influences on the freshwater River Nile Damietta Branch. Based on the available literature, this is the first documentation of this freshwater diatom species for Egypt, and the second record for the African continent. Two green motile microalgae, Chlamydomonas proboscigera and Gonium pectorale, were isolated and identified from the terrestrial biomes of the arid habitat “Wadi El-Atshan” in the Eastern Desert of Egypt. C. proboscigera is reported herein for the first time in the Egyptian algal flora, while G. pectorale is poorly documented in the available literature. In light of our findings, the Egyptian habitats, particularly the isolated desert ecosystems, are interesting biodiversity hotspots and have a richer algal microflora than earlier anticipated. Furthermore, more in-depth taxonomic studies, using a combined polyphasic approach, are needed not only to foster our knowledge of the Egyptian and African algal and cyanobacterial diversity and biogeography, but also to be further used in applied environmental sciences. Full article
(This article belongs to the Special Issue Biodiversity of Freshwater Ecosystems: Monitoring and Conservation)
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18 pages, 8631 KiB  
Article
Flow Characteristics and Pressure Pulsation Analysis of Cavitation Induced in a Double-Volute Centrifugal Pump
by Yongsha Tu, Xueying Zhao, Lifeng Lu, Wenjie Zhou, Siwei Li, Jin Dai, Zhongzan Wang, Yuan Zheng and Chunxia Yang
Water 2025, 17(3), 445; https://doi.org/10.3390/w17030445 - 5 Feb 2025
Abstract
Cavitation is a complex multiphase flow phenomenon, and the generation of transient phase transitions between liquid and vapor during cavitation development leads to multi-scale vortex motion. The transient cavitation dynamics and centrifugal pump’s rotor–stator interaction will induce pressure fluctuations in the impeller and [...] Read more.
Cavitation is a complex multiphase flow phenomenon, and the generation of transient phase transitions between liquid and vapor during cavitation development leads to multi-scale vortex motion. The transient cavitation dynamics and centrifugal pump’s rotor–stator interaction will induce pressure fluctuations in the impeller and the volute fluid of the centrifugal pump, resulting in a complex flow field structure. Based on the Schnerr–Sauer cavitation model and SST k-ω turbulence model, this paper studies the transient characteristics of the cavitation-induced unsteady flow in the centrifugal pump and the excitation response to the pressure pulsation in the volute under different flow conditions, taking the large vertical double-volute centrifugal pump as the research object. The results indicate the following: As the impeller rotates, in the external excitation response, the jet-wake flow structure at the centrifugal pump blade outlet shows an increase in the blade frequency signal. This is evident near the measurement points of the volute tongue and separator. When severe cavitation occurs, the maximum amplitude at the blade frequency in the volute shifts from the pump tongue (30°) to the downstream of the tongue (45°). The value of fpmax is 3.1 times that when NPSHa = 8.88 m. By applying the Omega vortex identification method, it can be seen that the interaction between the vortices at the blade trailing edge and the stable vortex in the volute tongue undergoes a process of elongation, fusion, separation, and recovery. This represents the downstream influence of the impeller on the volute. When Q = 0.9Qd, the process of the blade passage vortex tail detaching and dissipating in the impeller flow path can be observed, demonstrating the upstream influence of the volute on the impeller. Full article
(This article belongs to the Special Issue Advanced Numerical Approaches for Multiphase and Cavitating Flows)
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18 pages, 276 KiB  
Conference Report
New Frontiers in the Law of the Sea and Policy Integration
by Kangjie Sun, Muneeb Khan, Aiman Bibi and Yen-Chiang Chang
Water 2025, 17(3), 444; https://doi.org/10.3390/w17030444 - 5 Feb 2025
Abstract
As global advancements accelerate, modernisation and technological developments are transforming the ocean sector, bringing new opportunities while also posing significant challenges. Nevertheless, these developments have exposed gaps in the existing legal framework of ocean governance—the law of the sea—which has yet to fully [...] Read more.
As global advancements accelerate, modernisation and technological developments are transforming the ocean sector, bringing new opportunities while also posing significant challenges. Nevertheless, these developments have exposed gaps in the existing legal framework of ocean governance—the law of the sea—which has yet to fully address many emerging complexities and new frontiers. Addressing these gaps requires rigorous gap analyses and collaborative discourse. To this end, the 11th Ocean Law and Governance International Symposium, themed “New Frontiers and the Law of the Sea”, was held in Dalian, China, on 27–28 September 2024, in a hybrid format—online and offline. The event was co-hosted by the School of Law and the National Institute of Ocean Governance at Dalian Maritime University, with support from Zhejiang University and the Chinese Society of the Law of the Sea. The symposium brought together 22 experts and scholars from around the world to discuss critical topics, including high seas and seabed governance, climate litigation, digitalisation, law enforcement, and pressing issues, such as BBNJ and MPP. The symposium provided essential interdisciplinary legal insights, laying a robust foundation for fostering new discourse in the academic arena, which, in turn, advances future research while informing the development of marine policies aimed at achieving sustainable ocean governance. This study critically evaluates whether the symposium successfully bridged gaps in the existing academic landscape and explores whether it offers a way forward for addressing the challenges associated with new frontiers and the law of the sea. Through empirical legal analysis, this study aims to assess the impact of the symposium in promoting further discussions and policy innovations necessary to meet evolving ocean governance needs. Full article
(This article belongs to the Special Issue Impact of Climate Change on Marine Ecosystems)
14 pages, 841 KiB  
Article
Prioritizing Transboundary Aquifers in the Arizona–Sonora Region: A Multicriteria Approach for Groundwater Assessment
by Elia M. Tapia-Villaseñor, Sharon B. Megdal and Eylon Shamir
Water 2025, 17(3), 443; https://doi.org/10.3390/w17030443 - 5 Feb 2025
Abstract
Groundwater is vital to the well-being of over 20 million people in the nearly 2000-mile-long, arid U.S.–Mexico border region, supporting agricultural, industrial, domestic, and environmental needs. However, persistent droughts over the past two decades, coupled with increasing water demand and population growth, have [...] Read more.
Groundwater is vital to the well-being of over 20 million people in the nearly 2000-mile-long, arid U.S.–Mexico border region, supporting agricultural, industrial, domestic, and environmental needs. However, persistent droughts over the past two decades, coupled with increasing water demand and population growth, have significantly strained water resources, threatening the region’s water security. These challenges highlight the importance of comprehensive transboundary aquifer assessments, such as those conducted through the Transboundary Aquifer Assessment Program (TAAP), a collaborative effort between the U.S. and Mexico to evaluate shared aquifers. The TAAP focuses on four aquifers: the Santa Cruz and the San Pedro in Arizona and Sonora and the Mesilla and the Hueco Bolson in Texas, New Mexico, and Chihuahua. With the need for additional aquifer studies in this arid region, it is important to determine and prioritize which aquifers would benefit most from transboundary assessment. This study aims to prioritize aquifers in the Arizona–Sonora region based on multiple criteria. The results from this study reveal regional disparities in the need for transboundary aquifer studies, with some aquifers highlighted due to their groundwater use for economic activities, while others stand out for their population density and the transboundary nature of the hydrogeologic units. By leveraging publicly available data, this research established a priority ranking for these aquifers to support decision-making processes in identifying and addressing the most critical aquifers for binational assessment, while providing a framework that can be replicated across other shared aquifers between the U.S. and Mexico and elsewhere. Full article
(This article belongs to the Section Hydrology)
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19 pages, 10320 KiB  
Article
Analysis of Runoff Variation Characteristics and Influencing Factors in the Typical Watershed of Miyun Reservoir, China
by Sheming Chen, Wanjun Jiang, Zhuo Zhang, Futian Liu, Jing Zhang and Hang Ning
Water 2025, 17(3), 442; https://doi.org/10.3390/w17030442 - 5 Feb 2025
Abstract
As an important drinking water source for Beijing, the capital of China, the water inflow of Miyun Reservoir has been decreasing year by year, which has affected the urban water supply security. To understand the variation trend of the inflow and analyze the [...] Read more.
As an important drinking water source for Beijing, the capital of China, the water inflow of Miyun Reservoir has been decreasing year by year, which has affected the urban water supply security. To understand the variation trend of the inflow and analyze the main factors influencing the runoff change, this research focused on the watershed of Miyun Reservoir as the target. Based on the runoff data from 1984 to 2020 at the outlet of the basin, as well as the precipitation, potential evaporation intensity, NDVI (normalized difference vegetation index), population, and GDP (Gross Domestic Product) data, combined with correlation analysis methods, empirical statistical methods, the SCRCQ (Slope Change Ratio of Cumulative Quantity) method, and the GIS, the interannual variation characteristics of various elements in the basin were analyzed, the correlation between runoff and other factors was studied, and the influencing degrees of precipitation, water surface evaporation intensity, human activities, and other factors on the runoff change in the basin were quantitatively separated. The research results showed that the runoff exhibited a distinct decreasing trend, and there were two mutation points in the basin runoff from 1984 to 2020, which were 1995 and 2014, respectively. The runoff change was divided into three stages: 1984–1995 (upward trend in T1), 1995–2014 (downward trend in T2), and 2014–2020 (stable trend in T3). Runoff was significantly correlated with four indicators: the summer leaf area index of the Chaohe River and Baihe River, the regional GDP and population, among which the correlation of the summer leaf area index was the largest. Compared with the period T1, the contribution rates of climate change to the runoff reduction in T2 and T3 were 6.38% and 5.73%, and the contribution rates of human activities to the runoff reduction were 93.62% and 94.27%, respectively. Therefore, the change in annual runoff in the Miyun Reservoir watershed is mainly affected by human activities, and the contribution of climate change to the runoff attenuation is weak. This study is significant in the maintenance and enhancement of runoff in typical watershed. Full article
(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)
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19 pages, 7974 KiB  
Article
Numerical Simulation and Optimization Study on the Flow Field Characteristics of a Double-Slot Spillway
by Shijie Shuai, Yanxia Zhang, Huixia Yang and Shun Wang
Water 2025, 17(3), 441; https://doi.org/10.3390/w17030441 - 5 Feb 2025
Abstract
To investigate the flow characteristics of a novel dual-slot overflow channel, a research approach integrating physical experiments and numerical simulations was adopted. A three-dimensional model of the overflow channel was developed, employing the RNG k-ε turbulence model and the VOF two-phase flow model [...] Read more.
To investigate the flow characteristics of a novel dual-slot overflow channel, a research approach integrating physical experiments and numerical simulations was adopted. A three-dimensional model of the overflow channel was developed, employing the RNG k-ε turbulence model and the VOF two-phase flow model to optimize the numerical simulation of the high-low dual-slot flow field. Physical experiments were conducted to verify and analyze the hydraulic characteristics of the high-low overflow channel, including the longitudinal water surface profile and flow patterns. The numerical simulation results aligned well with the physical model test results. By analyzing the flow field of the dual-slot counterflow spillway, the flow characteristics at both the spillway and outlet sections were identified. This study focused on the water surface profile along the spillway, the pressure distribution, and the counterflow characteristics of the protruding water tongue, and explored optimization strategies for the WES surface and spillway design. Physical model tests were conducted on the final optimized design, yielding good agreement between the theoretical predictions and experimental results, thereby confirming the feasibility of the energy dissipation methods for both high and low spillways. The research outcomes offer valuable references for related engineering applications. Full article
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14 pages, 4522 KiB  
Article
A Community-Led Assessment to Identify Groundwater-Dependent Lakes in Parkland County (Alberta, Canada)
by Brian Smerdon, Jenna Bahija Tarrabain Maccagno, Bradley Peter, Walter Neilson, Dave Mussell and David Trew
Water 2025, 17(3), 440; https://doi.org/10.3390/w17030440 - 5 Feb 2025
Abstract
Responding to a growing concern about impacts from anthropogenic activity on several dozen lakes, a group of citizens initiated and led a water quality sampling program that included characterizing groundwater dependence. The small lakes are located on hummocky glacial terrain near Edmonton, Alberta, [...] Read more.
Responding to a growing concern about impacts from anthropogenic activity on several dozen lakes, a group of citizens initiated and led a water quality sampling program that included characterizing groundwater dependence. The small lakes are located on hummocky glacial terrain near Edmonton, Alberta, Canada. A team of volunteers collected lake samples for a variety of limnological and ecological analyses to document lake health and trophic state, and collaborated with a university research group to identify groundwater dependence using specific environmental tracers (δ2H, δ18O, and 222Rn). Water chemistry and isotopic measurements are largely explained by the position of a lake within the local groundwater flow system. A simple metric to express the likelihood of groundwater dependence was calculated using the total dissolved solids (TDS), δ18O, and 222Rn values. Across the relatively small study area, a greater likelihood of groundwater dependence was determined for lakes located downgradient from an elevated recharge area. In contrast, where the water table was relatively flat, a lower likelihood of groundwater dependence was found. These results were similar to the spatial pattern of a trophic state, indicating that groundwater dependence may be one of the factors responsible for lake ecological status. The data generated by citizens and the knowledge gained about the hydrology of this area will help discussions between landowners and decision makers on how to best manage land use in this diverse landscape. Full article
(This article belongs to the Section Hydrogeology)
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27 pages, 6016 KiB  
Review
An Overview of Historical Development, Current Situation, and Future Prospects of Managed Aquifer Recharge in Türkiye
by Mehmet Korkut, Niels Hartog and Vural Yavuz
Water 2025, 17(3), 439; https://doi.org/10.3390/w17030439 - 5 Feb 2025
Abstract
Climate change, rapid population growth, and unsustainable water use in industry and agriculture have all significantly harmed the quantity and quality of groundwater resources. Managed aquifer recharge (MAR) offers a solution to these challenges, encompassing a variety of methods and strategies for protecting [...] Read more.
Climate change, rapid population growth, and unsustainable water use in industry and agriculture have all significantly harmed the quantity and quality of groundwater resources. Managed aquifer recharge (MAR) offers a solution to these challenges, encompassing a variety of methods and strategies for protecting and improving groundwater systems. This article provides a complete overview of MAR in Türkiye, concentrating on its historical development, current situation, and future prospects. MAR has been increasingly used to combat water scarcity since the 1960s, particularly in arid and semi-arid regions in Türkiye with significant groundwater depletion. The majority of completed managed aquifer recharge (MAR) projects in Türkiye employ in-channel modifications, accounting for 77%. This is followed by well recharge techniques and surface spreading methods, with values of 16% and 4%, respectively. Future projects are expected to focus on the southeastern and central regions, with in-channel modifications increasing to 90%. In comparison, methods such as well recharge (6%), surface spreading (3%), and other methods are limited. Despite the growing application of MAR, Turkey requires strong regulatory frameworks to ensure the safe and successful implementation of these methods, including groundwater quality, source water regulations, and geological concerns regionally. MAR can promote sustainable water management by minimizing the effects of population growth and climate change on groundwater resources. Full article
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11 pages, 2587 KiB  
Article
Links Between Two Duckweed Species (Lemna minor L. and Spirodela polyrhiza (L.) Schleid.), Light Intensity, and Organic Matter Removal from the Water—An Experimental Study
by Wojciech Pęczuła
Water 2025, 17(3), 438; https://doi.org/10.3390/w17030438 - 5 Feb 2025
Abstract
Duckweeds—a group of floating leaf macrophytes from the family of Lemnaceae—have become a major area of interest in the fields of basic and applied aquatic sciences in recent decades, including their use in water purification. Aiming to fulfill one of the gaps [...] Read more.
Duckweeds—a group of floating leaf macrophytes from the family of Lemnaceae—have become a major area of interest in the fields of basic and applied aquatic sciences in recent decades, including their use in water purification. Aiming to fulfill one of the gaps in the role of light intensity in duckweed efficiency in organic matter removal, we carried out a laboratory experiment with the use of two duckweed species: Lemna minor and Spirodela polyrhiza. Our main finding was that the intensity of light has a positive effect on the process of water purification from organic compounds by Lemna minor. However, this was not applicable to Spirodela polyrhiza due to the fact that the growth of the species was inhibited by high light intensities. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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16 pages, 14617 KiB  
Article
Room for Sea-Level Rise: Conceptual Perspectives to Keep The Netherlands Safe and Livable in the Long Term as Sea Level Rises
by Jos van Alphen, Stephan van der Biezen, Matthijs Bouw, Alex Hekman, Bas Kolen, Rob Steijn and Harm Albert Zanting
Water 2025, 17(3), 437; https://doi.org/10.3390/w17030437 - 5 Feb 2025
Abstract
An accelerated sea-level rise (SLR) may threaten the future livability of the Netherlands. Three perspectives to anticipate this SLR are elaborated here regarding technical, physical, and spatial aspects: Protect, Advance, and Accommodate. The overall objective was to explore the tools and measures that [...] Read more.
An accelerated sea-level rise (SLR) may threaten the future livability of the Netherlands. Three perspectives to anticipate this SLR are elaborated here regarding technical, physical, and spatial aspects: Protect, Advance, and Accommodate. The overall objective was to explore the tools and measures that are available for adaptation, assess their spatial impacts, and identify dos and don’ts in current spatial issues like housing, climate adaptation, infrastructure, and the energy transition. Each elaboration was performed by a consortium consisting of representatives from private parties (engineering consultancy, project contractors, (landscape) architects, economists), knowledge institutes (including universities), and government, using an iterative process of model computations and design workshops. The elaborations made clear that a realistic and livable future perspective for the Dutch Delta continues to exist, even with a maximum analyzed SLR of 5 m, and will consist of a combination of elements from all three perspectives. This will require large investments and space for new and upgraded water infrastructure and will have large impacts on land use, water availability, agriculture, nature, residential buildings, shipping, and regional water systems. There is still a significant degree of uncertainty regarding future SLR; therefore, it is not advisable to make major investment decisions at this time. Nevertheless, some no-regret measures are already clear: continuation of the protection of the Randstad agglomeration (Amsterdam, The Hague, Rotterdam, and Utrecht) and its economic earning potential for future generations, adaptation of agriculture to more brackish and saline conditions, designation of space for additional future flood protection, extra storage capacity (for river discharge and increased precipitation), river discharge, and sand extraction (for future coastal maintenance). The research identified concrete actions for today’s decision-making processes, even though the time horizon of the analysis captures centuries. Including the perspectives in long term, policy planning is already necessary because the transition processes will take decades, if not more than a century, to be implemented. Full article
(This article belongs to the Special Issue Climate Risk Management, Sea Level Rise and Coastal Impacts)
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5 pages, 175 KiB  
Editorial
Persistent and Emerging Organic Contaminants in Natural Environments
by Jasmin Rauseo, Francesca Spataro and Luisa Patrolecco
Water 2025, 17(3), 436; https://doi.org/10.3390/w17030436 - 5 Feb 2025
Abstract
In recent decades, the world has experienced the detrimental effects of the unchecked growth of various human activities, including industrialization, transportation, agriculture, and urbanization [...] Full article
(This article belongs to the Special Issue Persistent and Emerging Organic Contaminants in Natural Environments)
23 pages, 5247 KiB  
Article
Numerical Investigation of Flow Around Partially and Fully Vegetated Submerged Spur Dike
by Sohail Iqbal, Rizwan Haider, Ghufran Ahmed Pasha, Lun Zhao, Fakhar Muhammad Abbas, Naveed Anjum, Nadir Murtaza and Zeshan Abbas
Water 2025, 17(3), 435; https://doi.org/10.3390/w17030435 - 4 Feb 2025
Abstract
This study investigates the role of emerged vegetation in enhancing the performance of submerged spur dikes for better flow control and bank protection in river systems. The research utilizes a numerical model based on Computational Fluid Dynamics (CFD), validated with experimental data. After [...] Read more.
This study investigates the role of emerged vegetation in enhancing the performance of submerged spur dikes for better flow control and bank protection in river systems. The research utilizes a numerical model based on Computational Fluid Dynamics (CFD), validated with experimental data. After validation, the study explores various configurations of vegetated spur dike, adjusting the submergence heights of the impermeable spur dike to achieve porosity ranging from fully impermeable to highly porous. Porosity levels of 24%, 48%, and 72% were chosen based on the spur dike height and the effectiveness of staggered vegetation arrangements in maximizing drag and reducing velocity. This approach aims to determine their impact on flow structure, velocity, and turbulence characteristics. The results reveal that impermeable dikes create strong recirculation zones downstream, increasing the potential for bank erosion. Introducing vegetation on the dike, particularly at moderate porosities (24% and 48%), effectively disrupts this behavior by reducing downstream velocity and mitigating mass and momentum exchange concentration between the spur dike field and the mainstream. However, the highest porosity case (72%) offered reduced flow resistance, limiting its protective effectiveness. Analysis of velocity and stress distributions showed that vegetation porosity significantly impacts normal and shear stresses, influencing flow stability at critical points around the spur dike. The findings signify the potential of integrating vegetation into spur dike designs to achieve a balance between effective flow conveyance and erosion control even in the spur dike submergence condition. This approach can outperform conventional emerged impermeable spur dikes, as supported by previous studies that demonstrate the effectiveness of porous and vegetated structures in reducing flow resistance, minimizing stagnation zones, and improving sediment deposition compared to impermeable designs. Full article
(This article belongs to the Special Issue Research on River, Coastal and Estuarine Morphodynamics)
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23 pages, 16066 KiB  
Article
Forecasting the River Ice Break-Up Date in the Upper Reaches of the Heilongjiang River Based on Machine Learning
by Zhi Liu, Hongwei Han, Yu Li, Enliang Wang and Xingchao Liu
Water 2025, 17(3), 434; https://doi.org/10.3390/w17030434 - 4 Feb 2025
Abstract
Ice-jam floods (IJFs) are a significant hydrological phenomenon in the upper reaches of the Heilongjiang River, posing substantial threats to public safety and property. This study employed various feature selection techniques, including the Pearson correlation coefficient (PCC), Grey Relational Analysis (GRA), mutual information [...] Read more.
Ice-jam floods (IJFs) are a significant hydrological phenomenon in the upper reaches of the Heilongjiang River, posing substantial threats to public safety and property. This study employed various feature selection techniques, including the Pearson correlation coefficient (PCC), Grey Relational Analysis (GRA), mutual information (MI), and stepwise regression (SR), to identify key predictors of river ice break-up dates. Based on this, we constructed various machine learning models, including Extreme Gradient Boosting (XGBoost), Backpropagation Neural Network (BPNN), Random Forest (RF), and Support Vector Regression (SVR). The results indicate that the ice reserves in the Oupu to Heihe section have the most significant impact on the ice break-up date in the Heihe section. Additionally, the accumulated temperature during the break-up period and average temperature before river ice break-up are identified as features closely related to the river’s opening in all four feature selection methods. The choice of feature selection method notably impacts the performance of the machine learning models in predicting the river ice break-up dates. Among the models tested, XGBoost with PCC-based feature selection achieved the highest accuracy (RMSE = 2.074, MAE = 1.571, R2 = 0.784, NSE = 0.756, TSS = 0.950). This study provides a more accurate and effective method for predicting river ice break-up dates, offering a scientific basis for preventing and managing IJF disasters. Full article
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38 pages, 11762 KiB  
Article
Machine Learning-Based Reconstruction and Prediction of Groundwater Time Series in the Allertal, Germany
by Tuong Vi Tran, Aaron Peche, Robert Kringel, Katrin Brömme and Sven Altfelder
Water 2025, 17(3), 433; https://doi.org/10.3390/w17030433 - 4 Feb 2025
Abstract
State-of-the-art hydrogeological investigations use transient calibrated numerical flow and transport models for multiple scenario analyses. However, the transient calibration of numerical flow and transport models still requires consistent long-term groundwater time series, which are often not available or contain data gaps, thus reducing [...] Read more.
State-of-the-art hydrogeological investigations use transient calibrated numerical flow and transport models for multiple scenario analyses. However, the transient calibration of numerical flow and transport models still requires consistent long-term groundwater time series, which are often not available or contain data gaps, thus reducing the robustness and confidence of the numerical model. This study presents a data-driven approach for the reconstruction and prediction of gaps in a discontinuous groundwater level time series at a monitoring station in the Allertal (Saxony-Anhalt, Germany). Deep Learning and classical machine learning (ML) approaches (artificial neural networks (TensorFlow, PyTorch), the ensemble method (Random Forest), boosting method (eXtreme gradient boosting (XGBoost)), and Multiple Linear Regression) are used. Precipitation and groundwater level time series from two neighboring monitoring stations serve as input data for the prediction and reconstruction. A comparative analysis shows that the input data from one measuring station enable the reconstruction and prediction of the missing groundwater levels with good to satisfactory accuracy. Due to a higher correlation between this station and the station to be predicted, its input data lead to better adapted models than those of the second station. If the time series of the second station are used as model inputs, the results show slightly lower correlations for training, testing and, prediction. All machine learning models show a similar qualitative behavior with lower fluctuations during the hydrological summer months. The successfully reconstructed and predicted time series can be used for transient calibration of numerical flow and transport models in the Allertal (e.g., for the overlying rocks of the Morsleben Nuclear Waste Repository). This could lead to greater acceptance, reliability, and confidence in further numerical studies, potentially addressing the influence of the overburden acting as a barrier to radioactive substances. Full article
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13 pages, 3551 KiB  
Communication
The Loss of Ice Worm Glacier, North Cascade Range, Washington USA
by Mauri S. Pelto and Jill Pelto
Water 2025, 17(3), 432; https://doi.org/10.3390/w17030432 - 4 Feb 2025
Abstract
A forty-year record (1984–2023) of glacier mass balance and areal extent measurement documented the decline and loss of the Ice Worm Glacier in the North Cascade Range, Washington. After a period of minor variations from 1944 to 1986, the glacier lost 83% of [...] Read more.
A forty-year record (1984–2023) of glacier mass balance and areal extent measurement documented the decline and loss of the Ice Worm Glacier in the North Cascade Range, Washington. After a period of minor variations from 1944 to 1986, the glacier lost 83% of its area from 1986 to 2023 and had a cumulative mass loss of −31.5 m w.e. In 2023, the area at 32,000 m2 and the majority of the ice thickness at 2–10 m was insufficient to generate movement. The bottom of the glacier was observed in all existing crevasse features, and stream channels in 2023 at depths of 2–10 m. An ice cave extended the length of the glacier in 2024 illustrating an ice thickness of less than 8 m. This glacier area loss has led to declining glacier runoff into Hyas Creek and the Cle Elum River. Full article
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