Water

13 pages, 967 KB

Open AccessArticle

Effects of Glyphosate on the Growth and Toxicity of the Harmful Alga Prymnesium parvum Under Phosphorus Sufficiency and Limitation

by Shisbeth Tabora-Sarmiento, Reynaldo Patiño, Pablo Lamino, Toluwalase Ojeyemi, Mousumi Akter Mary, Sonia Muñoz, Jordan Crago and Gregory D. Mayer

Water 2026, 18(12), 1403; https://doi.org/10.3390/w18121403 (registering DOI) - 8 Jun 2026

Abstract

Nutrient-rich inputs into surface waters can promote harmful blooms of Prymnesium parvum by stimulating growth under favorable environmental conditions. Glyphosate can enter aquatic ecosystems and affect algal growth, potentially further influencing P. parvum blooms. The interaction effects of nutrient conditions and glyphosate on [...] Read more.

Nutrient-rich inputs into surface waters can promote harmful blooms of Prymnesium parvum by stimulating growth under favorable environmental conditions. Glyphosate can enter aquatic ecosystems and affect algal growth, potentially further influencing P. parvum blooms. The interaction effects of nutrient conditions and glyphosate on P. parvum toxicity, however, remain unknown. This study determined the effects of glyphosate on the growth and toxicity of P. parvum. Cultures were exposed to glyphosate (0, 0.1, 0.25, and 0.5 mg L⁻¹) under phosphorous (P)-sufficient (f/2 medium) and P-limited conditions (phosphate-free medium) and, for the 0.1 mg L⁻¹ cultures, P. parvum toxicity (10,000 cells mL⁻¹) to Daphnia pulex was assessed. The addition of 0.1 and 0.25 mg glyphosate L⁻¹ significantly stimulated P. parvum growth in P-sufficient conditions, resulting in the highest growth rates and final cell densities. In P-limited conditions, however, glyphosate had no effect. P-sufficient cultures with 0.1 mg glyphosate L⁻¹ exhibited higher toxicity compared to controls. Although toxicity under P limitation was consistently higher than under P sufficiency, glyphosate did not affect this toxicity. These results suggest that glyphosate, at environmentally relevant concentrations, stimulates the growth and toxicity of P. parvum under nutrient-sufficient but not nutrient-limited conditions. Full article

(This article belongs to the Special Issue Emerging Contaminants in Water Environments: Occurrence, Analysis and Ecotoxicity)

► Show Figures

Figure 1

22 pages, 4673 KB

Open AccessArticle

Assessment of Rural Water-Cycle Soundness for Rural Water Management

by Seungjin Maeng, Daye Kim, Seungwook Lee and Youngho Park

Water 2026, 18(12), 1402; https://doi.org/10.3390/w18121402 (registering DOI) - 8 Jun 2026

Abstract

This study aimed to establish an assessment system for rural water-cycle soundness across standard watersheds in Korea and to determine priorities for project implementation. As climate change, water-quality deterioration, and population aging in rural areas intensify, the need for an integrated approach to [...] Read more.

This study aimed to establish an assessment system for rural water-cycle soundness across standard watersheds in Korea and to determine priorities for project implementation. As climate change, water-quality deterioration, and population aging in rural areas intensify, the need for an integrated approach to rural water management has become increasingly important. The study was structured into five sectors: water use, water safety, water environment, carbon neutrality, and water-friendly amenity. Sector-specific indicators were selected, and normality assessment, standardization, and factor analysis were conducted to verify indicator suitability. Weights were estimated using principal component analysis (PCA) to enhance the objectivity of the evaluation. A total of 825 standard watersheds were assessed, and sectoral indices were integrated to derive a rural water-cycle soundness index, which was subsequently classified into five grades. Based on the overall grades and sector-specific results, the priority of each standard watershed for implementing rural water-cycle projects was determined. The proposed framework provides a scientific basis for identifying vulnerable rural areas from a water-cycle perspective and supports policy responses. It may also contribute to future rural water management policies and disaster response strategies. Full article

(This article belongs to the Special Issue Water Governance and Sustainable Water Resources Management, 2nd Edition)

► Show Figures

Figure 1

25 pages, 49219 KB

Open AccessArticle

Spatio-Temporal–Spectral Study of the Flow Field Around Dual Cylinders in a Curved Channel Based on the Data-Driven SPOD Method

by Fang Wang, Sihao Ren, Ying Zhang, Qixin Wei and Xianfa Qi

Water 2026, 18(12), 1401; https://doi.org/10.3390/w18121401 (registering DOI) - 8 Jun 2026

Abstract

Local scour and vortex-induced vibrations around cylindrical structures in curved channels pose significant risks to the safety and stability of critical hydraulic infrastructure, such as bridge piers. To address these engineering challenges and elucidate the underlying flow mechanisms, this study conducts numerical simulations [...] Read more.

Local scour and vortex-induced vibrations around cylindrical structures in curved channels pose significant risks to the safety and stability of critical hydraulic infrastructure, such as bridge piers. To address these engineering challenges and elucidate the underlying flow mechanisms, this study conducts numerical simulations of flow past two side-by-side circular cylinders of equal diameter in a curved channel under subcritical conditions at Re = 3900, using the Realizable kε turbulence model. Spectral Proper Orthogonal Decomposition (SPOD) is introduced to quantitatively characterize the energy distribution and dominant coherent structures. Taking the spacing ratio L/D and the placement angle α as key design parameters, the flow field characteristics, modal energy distribution, and coherent structure evolution are systematically investigated for two side-by-side cylinders in three-dimensional straight and curved channels. The numerical results show that, in the straight channel, as L/D increases from 2 to 4, the flow field evolves from strong coupled interference to weak interaction. The vortex shedding frequency structure evolves from a single dominant frequency to a multi-frequency distribution with rich harmonic components, indicating a transition in wake dynamics from energy concentration to multimodal dispersion, accompanied by a significant improvement in flow stability. Under curved channel conditions, the results reveal an asymmetric flow field caused by pronounced energy concentration on the inner side of the channel. SPOD analysis further indicates that as the placement angle α increases from 30° to 90°, the modal energy distribution changes from concentrated to dispersed, the frequency spectrum broadens with enhanced harmonic components, and flow instability gradually intensifies. Overall, the spacing ratio L/D mainly governs the wake-interference pattern, whereas the placement angle α regulates the frequency structure and energy distribution. Among all the cases investigated, relatively favorable flow stability is achieved at L/D = 4 and α = 30°. The SPOD-derived modal energy distributions show that the streamwise fluctuation length of the dominant-mode energy is approximately 0.25 m at α = 30°, compared with 0.5 m at α = 90°, with the energy bandwidth nearly doubling. The combined CFD-SPOD approach effectively captures energy evolution and coherent structure characteristics of complex flows across spatial, temporal, and spectral dimensions. This enables a shift from conventional flow-field description to frequency-based mechanism analysis and provides a theoretical basis for structural layout optimization and scour protection in hydraulic engineering. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

► Show Figures

Figure 1

20 pages, 2096 KB

Open AccessArticle

Effects of Channel Modification and Precipitation on Fish Habitat in a Small Watershed: A Case Study of Gaoliao Creek in Taiwan

by Tung-Jer Hu, Hsiang-Yi Hsu, Chi-Rong Chung, Shang-Hao Wu and Cho-Han Yeh

Water 2026, 18(12), 1400; https://doi.org/10.3390/w18121400 (registering DOI) - 8 Jun 2026

Abstract

This study developed a novel framework integrating UAV-derived orthophotography, deep learning-based substrate classification, two-dimensional hydraulic modeling, Froude number (Fr) analysis, and multispecies habitat suitability assessment to evaluate the effects of channel modification and precipitation on fish habitats in Gaoliao Creek, eastern [...] Read more.

This study developed a novel framework integrating UAV-derived orthophotography, deep learning-based substrate classification, two-dimensional hydraulic modeling, Froude number (Fr) analysis, and multispecies habitat suitability assessment to evaluate the effects of channel modification and precipitation on fish habitats in Gaoliao Creek, eastern Taiwan. Habitat changes under baseflow and rainfall-induced high-flow conditions were quantified using Fr-based hydraulic habitat availability and Habitat Suitability Index (HSI)- and Combined Habitat Suitability Index (CHSI)-based habitat suitability. Channel modification transformed the channel from a deep and slow-flowing system into a shallower and faster-flowing environment. Under baseflow conditions, the proportion of available habitat meeting the adopted hydraulic criteria decreased from 81.6% to 73.9%, whereas the CHSI-derived proportion of weighted usable area (PUA) increased from 0.300 to 0.323 due to favorable substrate composition. During rainfall events, habitat availability and suitability declined markedly during peak flows and recovered as discharge receded. Compared with the pre-engineering channel, the modified channel exhibited greater sensitivity to short-term hydrological fluctuations but effectively prevented overbank flooding during the selected extreme rainfall event. These findings highlight the trade-off between flood-control benefits and ecological resilience and emphasize the importance of maintaining habitat heterogeneity in river management. Because the analyses were based on a single typhoon-related rainfall event and lacked direct biological validation, the results should be interpreted as event-specific predictions requiring further verification. Full article

(This article belongs to the Special Issue Advances in Hydrology and Hydraulics: Integrating Aquatic Biota and River Ecosystem Processes)

39 pages, 2319 KB

Open AccessArticle

Reuse of Drinking Water in the Cities: Types of Conflict, Legitimacy and Governance

by Juan Franco-Quintero, Carlos Rizo-Maestre and María Dolores Andújar-Montoya

Water 2026, 18(12), 1399; https://doi.org/10.3390/w18121399 - 7 Jun 2026

Abstract

Potable water reuse (direct and indirect; DPR/IPR) is increasingly proposed to strengthen urban water security under climate variability, water scarcity, and rising demand. Although technological barriers have decreased considerably, many projects continue to face intense social and political conflicts. By developing a conceptual [...] Read more.

Potable water reuse (direct and indirect; DPR/IPR) is increasingly proposed to strengthen urban water security under climate variability, water scarcity, and rising demand. Although technological barriers have decreased considerably, many projects continue to face intense social and political conflicts. By developing a conceptual framework to analyze the conflicts associated with DPR/IPR, this article examines how justification, acceptance, urgency, and actor agency interact to shape why some technically viable reuse initiatives are consolidated, transformed, or blocked. The study proposes three complementary typological matrices: Justification × Acceptance (J × A), Justification × Urgency (J × U), and Demands × Repertoires (D × R). These matrices integrate the structural conditions of the projects with the strategic dynamics of the actors involved. The framework is illustrated by a comparative international corpus of 25 DPR/IPR cases, compiled through a realist synthesis of academic literature, technical reports, institutional documents, and media evidence. The comparative case synthesis suggests that project trajectories do not depend solely on technological maturity or water scarcity. Instead, they are driven by how configuration changes and the strategic capacity of actors shape collective demands, narratives, and repertoires of action. Consequently, the advancement, transformation, or blocking of potable reuse projects is mainly explained by how these strategies shape the legitimacy of water risk governance. Full article

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

► Show Figures

Figure 1

18 pages, 2304 KB

Open AccessArticle

Integrated Physicochemical Characterization of Techirghiol Sapropelic Mud and Its Relevance for Balneotherapy

by Traian-Virgiliu Surdu, Monica Surdu, Irina Franciuc, Elena-Roxana Tucmeanu, Alin-Iulian Tucmeanu, Lucian Șerbănescu, Elena Mocanu, Maria Fulina, Olga Surdu, Stere Popescu, Iulian Manac, Florin Daniel Enache, Dragoș Brezeanu and Vlad Iustin Tica

Water 2026, 18(12), 1398; https://doi.org/10.3390/w18121398 - 7 Jun 2026

Abstract

Background: Sapropelic mud from Techirghiol Lake has been used therapeutically under medical supervision for more than 170 years; however, its comprehensive physicochemical characterization under application-relevant conditions remains insufficiently documented. This study aimed to evaluate the physicochemical properties, mineral and organic composition, ion-exchange capacity, [...] Read more.

Background: Sapropelic mud from Techirghiol Lake has been used therapeutically under medical supervision for more than 170 years; however, its comprehensive physicochemical characterization under application-relevant conditions remains insufficiently documented. This study aimed to evaluate the physicochemical properties, mineral and organic composition, ion-exchange capacity, and potential therapeutic mechanisms of Techirghiol sapropelic mud. Methods: Mud samples were analyzed using standardized physicochemical and analytical techniques to determine pH, water content, granulometry, mineral composition, organic fraction, and trace elements. Results: The results indicate that Techirghiol mud is a highly hydrated alkaline peloid characterized by a complex mineral–organic system. Major elements included sodium, calcium, and magnesium, while trace elements such as manganese, iron, and zinc were present in relevant concentrations. The organic fraction, composed of humic substances, lipids, and proteins, reflected advanced but incomplete humification processes. Conclusions: The findings demonstrate the complex physicochemical composition of Techirghiol sapropelic mud and provide a scientific basis for further studies regarding its properties and applications. Full article

(This article belongs to the Special Issue Groundwater for Health and Well-Being)

► Show Figures

Figure 1

23 pages, 27591 KB

Open AccessArticle

Comprehensive Ecological Health Assessment of Estuarine and Coastal Ecosystems Based on Remote Sensing and Multi-Source Data: A Case Study of Qinzhou Bay

by Ru Zhang, Hanqing Liu, Wenlu Lan, Hongda Hu, Xiaoyan Peng, Jia Sun and Wenlong Jing

Water 2026, 18(12), 1397; https://doi.org/10.3390/w18121397 - 7 Jun 2026

Abstract

Estuarine and coastal ecosystems are facing significant threats from compounded pressures, such as land-based pollution and mariculture activities. These ecosystems confront severe challenges, including increasing environmental burdens and declining ecological health. Traditional evaluation methods that rely on statistical data struggle to meet the [...] Read more.

Estuarine and coastal ecosystems are facing significant threats from compounded pressures, such as land-based pollution and mariculture activities. These ecosystems confront severe challenges, including increasing environmental burdens and declining ecological health. Traditional evaluation methods that rely on statistical data struggle to meet the requirements for refined management of estuarine and coastal water environments. Taking Qinzhou Bay as a case study, this research incorporated multi-source data (including water quality indicators retrieved from remote sensing imagery, mariculture distribution, and land use information) into an integrated ecological health assessment system that combined remotely sensed data with the Pressure–State–Response (PSR) model. This approach enables a spatially continuous and quantitative evaluation of ecological health conditions for August 2015 (flood season), December 2015 (non-flood season), May 2022 (flood season), and December 2022 (non-flood season). The results indicated significant seasonal differences in the ecological health of Qinzhou Bay, with conditions generally better during the non-flood season than the flood season. Based on a comparison between the indicative estimation for 2015 and the inversion results for 2022, the overall ecological health index in 2022 showed an increasing trend, although some nearshore and estuarine areas experienced a declining trend. This study incorporated multi-source data, including remote sensing, into the PSR model framework, thereby advancing ecological health assessment from conventional discrete station-based evaluation to spatially continuous assessment. The effectiveness of this methodological approach in identifying spatiotemporal variations in the ecological health of estuarine and coastal zones was validated, providing scientific support for the refined management of estuarine and coastal water environments and ecological restoration. Full article

(This article belongs to the Special Issue Remote Sensing and GIS in Water Resource Management)

► Show Figures

Figure 1

29 pages, 28561 KB

Open AccessArticle

Dam Failure Mechanism and Risk Assessment Under Extreme Rainfall Conditions: Case Study of Hubuling Reservoir

by Xixuan Zhang, Chao Yin, Jingjing Li and Tianqi Sun

Water 2026, 18(12), 1396; https://doi.org/10.3390/w18121396 - 7 Jun 2026

Abstract

To reveal the overtopping dam-break mechanism under extreme rainfall conditions and assess downstream flood risk, a series of dam-break flume tests, flood routing simulations and inundation risk assessments were conducted. Using the Hubuling Reservoir in Rizhao City, Shandong Province as a case study, [...] Read more.

To reveal the overtopping dam-break mechanism under extreme rainfall conditions and assess downstream flood risk, a series of dam-break flume tests, flood routing simulations and inundation risk assessments were conducted. Using the Hubuling Reservoir in Rizhao City, Shandong Province as a case study, a circulating extreme rainfall dam-break flume system with a controllable reservoir water level was constructed at a geometric similarity scale of 1:70. Four test conditions were designed: no rainfall and 50-year, 100-year and 2000-year rainfall return periods. Pore water pressure, earth pressure and water content sensors were embedded in critical dam sections to monitor real-time internal dynamic responses. The results show that, due to the combined effect of the highest rainfall intensity, rapid reservoir water-level rise, progressive infiltration-induced weakening and concentrated surface erosion, a dam-break occurs only under the 2000-year rainfall return period. The failure process is divided into four stages: initial infiltration, slope surface scour, overtopping initiation and rapid breach development. Based on dam-break parameters obtained by physical model tests, a two-dimensional numerical using HEC-RAS was conducted. The results show that, under the 2000-year rainfall return period, the flood reaches the downstream area at 80 min after dam failure. The maximum inundation area reaches 15.20 km² at 200 min, with a maximum inundation depth of 11.80 m and a maximum inundation duration of 144 h. By integrating the maximum inundation depth, inundation duration and land use conditions, the expected economic loss is estimated to be 690 million yuan. The results provide important support for dam-break early warnings, emergency management and disaster mitigation of similar small- and medium-sized reservoirs. Full article

(This article belongs to the Special Issue Intelligent Safety Diagnosis and Reinforcement of Water-Related Buildings)

18 pages, 4131 KB

Open AccessArticle

Algae–Aerobic Granular Sludge (AAGS) for Wastewater Treatment: Granule Stability, Pollutant Removal Performance, and Biodiesel Potential

by Rustiana Yuliasni, Yob Ihadjadene, Khongorzul Mungunkhuyag, Juliane Steingroewer, Thomas Walther and Felix Krujatz

Water 2026, 18(12), 1395; https://doi.org/10.3390/w18121395 - 7 Jun 2026

Abstract

This study investigated the granule development and pollutant removal performance of algae–aerobic granular sludge (AAGS) and aerobic granular sludge (AGS) for wastewater treatment, as well as the characterization of the fatty acid methyl ester (FAME) composition for biodiesel production. The results demonstrated that [...] Read more.

This study investigated the granule development and pollutant removal performance of algae–aerobic granular sludge (AAGS) and aerobic granular sludge (AGS) for wastewater treatment, as well as the characterization of the fatty acid methyl ester (FAME) composition for biodiesel production. The results demonstrated that AAGS had overall better pollutant removal performance than AGS. The average removal of total nitrogen (TN), total phosphate (TP), and chemical oxygen demand (COD) of AAGS were 96.16 ± 6.8%, 58.22 ± 5.44%, and 79.5 ± 5.48%, respectively, while AGS removed 70.95 ± 31.63%, 29.53 ± 12.54, and 74.8 ± 12.13% of TN, TP, and COD, respectively. AAGS required less time (16 days) than AGS (44 days) to achieve complete TN removal. AAGS produced more bound EPS than AGS, which makes it more stable. Scanning electron microscopy (SEM) surface images showed that AGS has dense surface morphology with mineral precipitate layers, while AAGS has a porous surface with filamentous algae intertwined. The biodiesel potential (fatty acid yield) of AAGS was 45% higher than that of AGS. The fatty acid methyl ester (FAME) yields obtained in AAGS and AGS were 64.4 ± 2.61 mg/g suspended solids (SSs) and 44.4 ± 0.9 mg/g SSs, respectively. AAGS has higher proportions of monounsaturated fatty acids (MUFAs/oleate) and polyunsaturated fatty acids (PUFAs/linoleate) than AGS. Thus, AAGS generates a more prospective biodiesel potential. Full article

(This article belongs to the Special Issue Algae-Based Technology for Wastewater Treatment)

► Show Figures

Figure 1

12 pages, 648 KB

Open AccessArticle

Warmer Temperatures and Smaller Body Size May Favor Biological Competition of Invasive Neogobius fluviatilis with Native Gobio gobio in Central European Bioregion

by Alicja Pawelec, Małgorzata Grzesiuk, Anna Hauler and Jay R. Stauffer, Jr.

Water 2026, 18(12), 1394; https://doi.org/10.3390/w18121394 - 7 Jun 2026

Abstract

We conducted experiments to assess the importance of the effects of interactions between individuals of co-occurring species, the Common Gudgeon Gobio gobio, native to Europe, and the invasive Monkey Goby Neogobius fluviatilis. We examined the influence of the size of the competitor and [...] Read more.

We conducted experiments to assess the importance of the effects of interactions between individuals of co-occurring species, the Common Gudgeon Gobio gobio, native to Europe, and the invasive Monkey Goby Neogobius fluviatilis. We examined the influence of the size of the competitor and the temperature of the water on competition for food between these two species. To investigate whether this food competition is dependent on the size of invasive competitors, we used three size classes of the invasive N. fluviatilis and a single size class of the native G. gobio in a tank-based experiment. To reflect the possible impact of temperature, we used two different water temperatures: 16 °C preferred by the G. gobio and 22 °C preferred by the N. fluviatilis. Based on the number of prey consumed, time to start feeding, and the total time spent hunting prey, we provided direct confirmation that the invasive N. fluviatilis in Europe is the superior competitor for food at both tested temperatures, eating twice as much prey, feeding 2–4 times faster, and spending up to three times more time on hunting. Food competition was size-dependent: the greater threat for native species is invasive fish, which are smaller or similar to them in size. Warmer temperatures (22 °C) gave more than twice as much advantage to the invaders under all tested feeding parameters. Therefore, we concluded that populations of invasive N. fluviatilis present a serious threat to native European benthic fish species (i.e., G. gobio). Increasing temperatures, better tolerated by invasive species, compound this problem. Full article

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

► Show Figures

Figure 1

16 pages, 3879 KB

Open AccessArticle

Effects of Precipitation Trends, Extremes, and Antecedent Moisture Controls on Landslide Triggering in Hum na Sutli and Northern Croatia

by Matko Patekar, Laszlo Podolszki, Igor Karlović and Kosta Urumović

Water 2026, 18(12), 1393; https://doi.org/10.3390/w18121393 - 7 Jun 2026

Abstract

Both variability in precipitation and rainfall extremes are key drivers of landslide activity, yet their combined influence with antecedent moisture conditions remains insufficiently quantified at regional or local scales. In this study, daily precipitation records over the past 25 years (2000–2024) were analyzed [...] Read more.

Both variability in precipitation and rainfall extremes are key drivers of landslide activity, yet their combined influence with antecedent moisture conditions remains insufficiently quantified at regional or local scales. In this study, daily precipitation records over the past 25 years (2000–2024) were analyzed for five meteorological stations in Northern Croatia across multiple temporal scales. The aim was to investigate the impact of precipitation patterns and regime changes on landslide triggering in Hum na Sutli and the wider area. Statistical analyses (linear regression, Mann–Kendall trend assessment, and Pearson correlation) were applied, and antecedent wetness was quantified using the antecedent precipitation index (API). Results indicate weak, statistically insignificant positive trends in annual precipitation, accompanied by strong interannual variability and coherent regional behavior. Seasonal analysis reveals the dominance of warm-season precipitation with pronounced extremes, while short-duration and multi-day rainfall events exhibit high variability and clustering. The 2024 Hum na Sutli landslide coincided with elevated cumulative precipitation and sustained high API values, despite the absence of exceptionally extreme single-day rainfall events. These findings highlight the critical role of antecedent moisture accumulation combined with episodic high precipitation in slope failure. The study supports a conceptual model in which landslide triggering is governed by the interaction of preconditioning and short-term hydrometeorological factors, providing a basis for improved hazard and risk assessment. Additionally, preliminary rainfall threshold values are proposed as practical early-warning guidance for local communities in landslide-prone regions in Northern Croatia. Full article

(This article belongs to the Special Issue Water Management and Geohazard Mitigation in a Changing Climate)

► Show Figures

Figure 1

39 pages, 5728 KB

Open AccessReview

Role of Internet of Things and Artificial Intelligence in Water Distribution Networks

by Zarin Mosarat, Md Mamunur Rashid, AKM Ahasan Habib, Sadia Parvin Sanchita, AFM Zainul Abadin, Arnob Ghosh and Thomas M. T. Lei

Water 2026, 18(12), 1392; https://doi.org/10.3390/w18121392 - 6 Jun 2026

Abstract

Non-revenue water (NRW) entails serious problems for water distribution networks (WDNs), including contamination, leakage, unauthorized use, and inefficient invoicing. These issues lead to large financial losses and operational inefficiencies. This work investigates and focuses on Internet of Things (IoT) and Artificial Intelligence (AI) [...] Read more.

Non-revenue water (NRW) entails serious problems for water distribution networks (WDNs), including contamination, leakage, unauthorized use, and inefficient invoicing. These issues lead to large financial losses and operational inefficiencies. This work investigates and focuses on Internet of Things (IoT) and Artificial Intelligence (AI) technologies involving WDNs that could be employed for monitoring NRW distribution. According to the analysis, NRW resulting from contamination, unauthorized connections, and unpaid water bills causes water companies to lose a substantial amount of money. In the water industry, the implementation, utilization, and installation of IoT–AI technologies can help decision-making, improve sustainable development, develop innovative products and services, and find solutions. Furthermore, IoT technologies and protocols can assist the water sector in reducing NRW, improving WDN management and operations, and identifying key challenges, including sensor reliability, communication constraints, cybersecurity concerns, scalability issues, and cost-effectiveness in practical deployment. This study offers an integrated analysis of IoT technologies, AI techniques, communication protocols, and NRW management strategies within a unified WDN perspective to earlier review articles that independently concentrate on leakage detection, IoT frameworks, or AI applications. Lastly, the study’s originality depends on its ability to show how theoretical advancements and technologies can be commercialized in cost-effective smart water distribution systems, contributing to the advancement of resilient urban water infrastructure and smart city development. Full article

(This article belongs to the Special Issue Applications of Artificial Intelligence (AI) in Water Resources System, 2nd Edition)

► Show Figures

Figure 1

25 pages, 6228 KB

Open AccessArticle

A Multi-Objective Trade-Off Analysis with NSGA-II and Pareto Strategies for Total Phosphorus Load Allocation and Engineering Configuration in Yangcheng Lake Basin

by Zijiajie Peng, Yingdong Yu and Yongzhou Cheng

Water 2026, 18(12), 1391; https://doi.org/10.3390/w18121391 - 6 Jun 2026

Abstract

Yangcheng Lake, the third largest freshwater lake in the Taihu Plain (118.68 km²), serves critical functions in drinking water supply, aquaculture, and ecological regulation. This study aims to address the challenge of optimizing total phosphorus load allocation and engineering project configuration [...] Read more.

Yangcheng Lake, the third largest freshwater lake in the Taihu Plain (118.68 km²), serves critical functions in drinking water supply, aquaculture, and ecological regulation. This study aims to address the challenge of optimizing total phosphorus load allocation and engineering project configuration in the Yangcheng Lake basin by developing a multi-objective optimization model that integrates environmental, social, and economic dimensions with the goal of achieving three specific objectives: (1) maximizing ecological benefits, (2) minimizing life-cycle costs, and (3) minimizing the environmental Gini coefficient. The NSGA-II algorithm was used, with hyperparameters calibrated via orthogonal experiments and HV-GD evaluation. Under a normal flow year scenario, total phosphorus (TP) load allocation was optimized for an agricultural watershed where livestock manure contributes 86.5% of TP pollution. Five selection strategies (Economic Priority, Ecological Priority, Equity Priority, Ideal Point Method, Game Theory) were applied to the Pareto front. Results show synergy between ecological and equity objectives, both competing with economic cost. Optimal hyperparameters were a population size of 1000 and 1000 iterations. Among strategies, the Ideal Point Method achieved the best compromise (economic cost: 5772.7; Gini coefficient < 0.30). The proposed framework provides scientific support for pollution load allocation in plain river network regions, helping decision-makers balance economic development, ecological protection, and social equity. Full article

(This article belongs to the Topic Environmental Pollutant Management and Control)

27 pages, 2802 KB

Open AccessArticle

Bulk Decay Coefficient Assessment for Different Water Temperatures: Ensemble Temperature State Estimation Approach

by Elena Cejas, Sarai Díaz and Javier González

Water 2026, 18(12), 1390; https://doi.org/10.3390/w18121390 - 6 Jun 2026

Abstract

Most water supply systems rely on free chlorine residual to ensure disinfection through the network and at the user’s tap. Temperature increase is known to accelerate the chlorine decay process and is typically associated with water quality deterioration. This is a challenging situation [...] Read more.

Most water supply systems rely on free chlorine residual to ensure disinfection through the network and at the user’s tap. Temperature increase is known to accelerate the chlorine decay process and is typically associated with water quality deterioration. This is a challenging situation under the current climate change scenario, which is bound to increase average temperatures and the intensity and frequency of extreme-temperature events. Moreover, water temperature varies through the supply network due to seasonal changes and thermal interaction, so it is not straightforward to model chlorine evolution through the network considering temperature effects. Previous works have highlighted the importance of considering the Arrhenius formula when accounting for temperature changes in the bulk chlorine decay coefficient (typically characterized through bottle tests), but these studies have never explicitly considered the uncertainty of the bulk decay coefficient itself. Recent studies have identified that the uncertainty of the bulk decay coefficient may be relevant (>15%) and should be considered when cross-comparing bottle test results (e.g., at different temperatures). The aim of this work is to propose a new method that statistically computes the mean and standard deviation of the key parameters in the Arrhenius formula (the reference bulk decay coefficient

k_{b_{0}}

and activation coefficient E/R) from free chlorine residual bottle test results (with replicated measurements over samples from the entrance to the network) at different temperatures. This approach (here called the ensemble temperature state estimation approach) ensures that bottle test measurements at different temperatures are jointly assessed to derive an equation that provides the bulk decay coefficient at any water temperature. Therefore, the new method improves the characterization of the bulk decay component (and its associated uncertainty) and could be crucial for improving the understanding and modeling capabilities of complex chlorine dynamics within supply infrastructure. Full article

(This article belongs to the Section Urban Water Management)

► Show Figures

Figure 1

19 pages, 15571 KB

Open AccessReview

A Review of Water Distribution System Modeling and Calibration: Insights into Desalinated Water Integration

by Jefferson S. Rocha, José Gescilam S. M. Uchôa, Bruno M. Brentan and Iran E. Lima Neto

Water 2026, 18(12), 1389; https://doi.org/10.3390/w18121389 - 6 Jun 2026

Abstract

The management of water availability in urban areas has become progressively more complex due to adverse climatic conditions and the continuous growth in water demand. These concerns have driven the search for alternative water supply sources, such as desalination, as well as the [...] Read more.

The management of water availability in urban areas has become progressively more complex due to adverse climatic conditions and the continuous growth in water demand. These concerns have driven the search for alternative water supply sources, such as desalination, as well as the need for a deeper understanding of the hydraulic and operational behavior of water distribution systems (WDS) in the face of these challenges. This study presents an exploratory and integrative literature review on the modeling and calibration of WDS, with an emphasis on their application to the analysis of hydraulic and operational impacts associated with the integration of desalinated water into large-scale WDS. The results, supported by bibliometric analysis and a comparative assessment of 28 real-world calibration studies, highlight advances in modeling and calibration techniques and identify engineering-based trends and research gaps related to desalinated water integration in WDS. These include increased pressure heterogeneity associated with desalinated water injection points, challenges related to intermittent operation, and the need for properly managed storage reservoirs. Overall, the findings reinforce hydraulic modeling and calibration as central tools for the integrated assessment of desalination impacts in large-scale water distribution systems. Full article

(This article belongs to the Special Issue The Safety Operations and Intelligent Control of Water Network Engineering Systems)

► Show Figures

Figure 1

16 pages, 922 KB

Open AccessArticle

Genotoxic Effects of River Waters in Northern Armenia Evaluated with Tradescantia Test Systems

by Rimma Avalyan, Alla Khosrovyan, Bardukh Gabrielyan, Rouben Aroutiounian and Anahit Atoyants

Water 2026, 18(12), 1388; https://doi.org/10.3390/w18121388 - 6 Jun 2026

Abstract

The quality of riverine water is largely influenced by anthropogenic activity; however, worldwide monitoring practices remain largely limited to assessing water physicochemical parameters. To evaluate the potential of river contaminants to cause biological effects, two standard tests with the Tradescantia plant were used: [...] Read more.

The quality of riverine water is largely influenced by anthropogenic activity; however, worldwide monitoring practices remain largely limited to assessing water physicochemical parameters. To evaluate the potential of river contaminants to cause biological effects, two standard tests with the Tradescantia plant were used: Trad-SHM (stamen hair mutations) and Trad-MN (appearance of micronuclei in sporogenic cells). Water samples were collected from nine localities along the two rivers of the Kura basin: before and after the towns of Spitak, Vanadzor, Tumanyan, Alaverdi, and before Akhtala. The sampling locations were impacted by different anthropogenic sources—domestic and agricultural (Spitak and Vanadzor) and domestic and mining (Tumanyan, Alaverdi, and Akhtala). The biological responses were compared to water quality monitoring data based on physicochemical parameters (ions and metals). Monitoring results indicated “good” or “average” water quality, except for the exceedance of Fe, Mn, Cu, and Pb concentrations in the mining-affected areas. However, Tradescantia showed significantly increased frequency of hair cell mutations and micronucleus formation from urban/agricultural to mining-affected samples. The multivariate PCA analysis distinguished between the samples by associating ammonium and nitrate levels with the samples from urban/agricultural areas and the concentrations of Fe, Mn, Co, and Al with the biological responses in mining-affected samples. However, most likely, toxic substances in the riverine waters acted synergistically. The results indicated that compliance with chemical standards does not necessarily equate to biological safety. They emphasize the need to incorporate biological effects into monitoring programs to improve their contribution to informed decision-making regarding environmental impacts. Full article

(This article belongs to the Special Issue Advancing Knowledge of the Impacts of Contaminants in Aquatic Environments)

► Show Figures

Figure 1

16 pages, 628 KB

Open AccessArticle

The Water Footprint of Food Loss and Waste in Saudi Arabia: Magnitude, Composition, and Policy Implications

by Fahad Alzahrani and Rady Tawfik

Water 2026, 18(12), 1387; https://doi.org/10.3390/w18121387 - 6 Jun 2026

Abstract

Food loss and waste (FLW) represent a significant source of resource inefficiency in water-scarce economies. This study quantifies the water footprint (WF) of FLW in Saudi Arabia using product-level blue, green, and grey WF coefficients from the Water Footprint Network database. Our analysis [...] Read more.

Food loss and waste (FLW) represent a significant source of resource inefficiency in water-scarce economies. This study quantifies the water footprint (WF) of FLW in Saudi Arabia using product-level blue, green, and grey WF coefficients from the Water Footprint Network database. Our analysis covers 3.997 million tons of FLW across 19 commodities grouped into cereals, fruits, vegetables, and meat. Results indicate that FLW is associated with a total blue and green WF of 7.3 billion m³, of which 2.1 billion m³ is blue water directly associated with managed water resources. The blue WF is equivalent to approximately 20% of agricultural water withdrawals and 62% of domestic water demand. Despite constituting only 13% of total FLW by mass, meat products account for 53% of the total water footprint, driven by their exceptionally high water intensity (7474 m³/ton). The consumption stage dominates water losses, contributing 56% of the total blue and green WF. Based on alternative water supply cost benchmarks, the blue WF embedded in FLW corresponds to an indicative production-cost equivalent ranging from 1.03 to 6.5 billion SAR. A 25% reduction in FLW could save over 500 million m³ of blue water annually. These findings demonstrate that FLW reduction represents an important supporting strategy for water resource management and provides a quantitative basis for prioritizing intervention across food groups and supply-chain stages. Full article

(This article belongs to the Special Issue Economic Approaches to Sustainable Water Management: Policy, Innovation, and Global Challenges)

► Show Figures

Figure 1

13 pages, 2399 KB

Open AccessArticle

Development of a Conceptual Hydrogeological Model Based on Geological Mapping and Stable Isotopes: A Case Study of Šmarna Gora, Slovenia

by Mitja Janža, Tamara Marković and Brigita Jamnik

Water 2026, 18(12), 1386; https://doi.org/10.3390/w18121386 - 6 Jun 2026

Abstract

Small decentralized water supply systems are often sensitive to local pollution and require a clear understanding of recharge conditions and the hydrodynamics within the water resource catchment. This study develops a conceptual hydrogeological model for the Šmarna Gora area based on geological mapping, [...] Read more.

Small decentralized water supply systems are often sensitive to local pollution and require a clear understanding of recharge conditions and the hydrodynamics within the water resource catchment. This study develops a conceptual hydrogeological model for the Šmarna Gora area based on geological mapping, long-term monitoring of chemical parameters, and stable isotope analyses (δ¹⁸O, δ²H) of precipitation and groundwater. The study was initiated in response to rising pollutant concentrations in the drinking water. Estimates of transit time (TT) and mean residence time (MRT) were used to characterize recharge, mixing processes, and differences between the SG and ZAVRH wells, the existing and alternative water supply wells. Isotope data show that the aquifer is predominantly recharged during colder periods and that Mediterranean air masses have become an increasingly important source of precipitation, suggesting a shift in precipitation patterns. The results indicate that SG has longer TT (6–8 months) and MRT (up to 1–2 years). In contrast, ZAVRH shows shorter TT and MRT (4–6 months), and lower pollutant concentrations. The hydrogeological regime in the catchment of the ZAVRH well is characterized by a dynamic, fast-flowing system with limited storage and more intensive dilution of contaminants by infiltrating water, whereas the catchment of the SG well functions as a deeper and more buffered aquifer with prolonged groundwater residence and a more direct hydraulic linkage to the contaminant source. The findings distinguish two hydrogeological regimes and provide a basis for planning water supply solutions and protection measures. Full article

(This article belongs to the Special Issue Application of Isotope Geochemistry in Hydrological Research)

► Show Figures

Figure 1

22 pages, 2892 KB

Open AccessArticle

Decomposition–Migration Cooperative Modeling Approach for Forecasting Runoff in Data-Scarce Watershed Areas

by Yiyang Yang, Xiangyu Sun, Siyu Cai, Xuefei Wu and Mingshuo Zhai

Water 2026, 18(12), 1385; https://doi.org/10.3390/w18121385 - 6 Jun 2026

Abstract

To address runoff forecasting inaccuracies caused by data gaps in reservoir operations, this paper proposes a collaborative modeling framework integrating deep learning, signal decomposition, uncertainty quantification, and transfer learning. Validated on the Wei River (source basin) and Yongding River (target basin) with similar [...] Read more.

To address runoff forecasting inaccuracies caused by data gaps in reservoir operations, this paper proposes a collaborative modeling framework integrating deep learning, signal decomposition, uncertainty quantification, and transfer learning. Validated on the Wei River (source basin) and Yongding River (target basin) with similar hydrological characteristics, the framework first constructs a Pyraformer-BiLSTM-LSS point forecasting model to enhance characterization of non-stationary runoff sequences. Then, the BLSO-VMD optimization decomposition technique filters and reconstructs forecasting noise, improving model robustness. Subsequently, a probabilistic interval forecasting model is developed via multi-task learning to reliably quantify uncertainty. To tackle data scarcity in the target domain, a “decomposition–reconstruction–transfer” learning mechanism transfers model knowledge from the source domain to the target domain. Results show that the framework achieves excellent performance in the source domain and successfully transfers to the data-scarce target domain, significantly enhancing the accuracy and stability of both point and interval forecasts. By establishing a collaborative modeling framework combining transfer learning and multi-task learning, along with an adaptive signal decomposition method based on BLSO and a multi-scale deep learning model, this study effectively addresses the challenges of accuracy and reliability in runoff forecasting for data-scarce basins. It provides a transferable and scalable technical pathway for runoff simulation and reservoir operation in hydrologically underserved regions, supporting sustainable water resource management and ecological protection. Full article

(This article belongs to the Special Issue Managing Water Under a New Hydrological Normal: Innovations for Resilience in the Face of Climate Change)

► 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