Water doi: 10.3390/w16060879
Authors: Heleen Jalink Carel Dieperink
In times of climate change, periods of drought will occur more frequently. This causes challenges for water use, ranging from limitations on the navigability of water courses, limited availability of water for irrigation and drinking water supply, reduced hydropower production, increasing concentrations of pollutants, deteriorating water quality, and ecosystem degradation. Dealing with droughts, however, is a complex puzzle due to the multi-level governance characteristics of international river basins and the need to meet the freshwater demands of all sectors involved. This increases the need to address drought issues in a coordinated way, along all levels of decision making. Thus far, the way this must be executed has been under-researched. This paper addresses this knowledge gap as it aims to provide design principles for good multi-level drought risk governance in international river basins. In order to meet our aim, we first reviewed literature on multi-level and good governance and established an assessment framework. This framework was applied in a case study on drought risk governance in the international Rhine basin. Policy documents were analyzed and key informants interviewed. We found that although the governance practice in the basin meets most of our framework criteria, differences between the international level, the Netherlands, Germany, and Switzerland also occurred. We have synthesized our findings into a list of 10 design principles for good multi-level drought risk governance, which could function as a starting point for the analysis and improvement of other multi-level drought risk governance practices.
]]>Water doi: 10.3390/w16060877
Authors: Brian G. Roche Michael A. Perez Wesley N. Donald Jarrell Blake Whitman
Sediment barriers are used on construction sites to protect downstream waterbodies from the impacts of sediment-laden stormwater runoff. Although ubiquitous on construction sites, many sediment barrier practices lack performance-based testing to determine effectiveness and treatment mechanisms, with previous evaluations being limited to conditions local to the Southeastern U.S., with conditions in other regions remaining untested. Testing was conducted to determine the effectiveness of woven silt fence barriers and provide structural improvements to common installation methods. Testing was conducted using a large-scale sediment barrier testing apparatus at the Auburn University—Stormwater Research Facility. The results from testing indicate that Nebraska DOT standard silt fence installations can be improved to reduce the risk of structural failures such as undermining, complete installation failure, slow dewatering, and overtopping. To improve structural performance, four modifications (a 15.2 cm [6 in.] offset trench, wooden posts, a dewatering board with an overflow weir, and a dewatering board with an overflow weir with adjusted post spacing) were tested. On average, 83% of introduced sediment was retained behind the tested barriers. The water quality results across the testing of standard and modified installations indicated that stormwater treatment was due to sedimentation within the impoundment formed by silt fence installations and not filtration through geotextile fabric.
]]>Water doi: 10.3390/w16060878
Authors: Charalampos Skoulikaris
Large-scale hydrological modeling is an emerging approach in river hydrology, especially in regions with limited available data. This research focuses on evaluating the performance of two well-known large-scale hydrological models, namely E-HYPE and LISFLOOD, for the five transboundary rivers of Greece. For this purpose, discharge time series at the rivers’ outlets from both models are compared with observed datasets wherever possible. The comparison is conducted using well-established statistical measures, namely, coefficient of determination, Percent Bias, Nash–Sutcliffe Efficiency, Root-Mean-Square Error, and Kling–Gupta Efficiency. Subsequently, the hydrological models’ time series are bias corrected through scaling factor, linear regression, delta change, and quantile mapping methods, respectively. The outputs are then re-evaluated against observations using the same statistical measures. The results demonstrate that neither of the large-scale hydrological models consistently outperformed the other, as one model performed better in some of the basins while the other excelled in the remaining cases. The bias-correction process identifies linear regression and quantile mapping as the most suitable methods for the case study basins. Additionally, the research assesses the influence of upstream waters on the rivers’ water budget. The research highlights the significance of large-scale models in transboundary hydrology, presents a methodological approach for their applicability in any river basin on a global scale, and underscores the usefulness of the outputs in cooperative management of international waters.
]]>Water doi: 10.3390/w16060875
Authors: Fanrong Kong Jin Liu Zaixin Xiang Wei Fan Jiancong Liu Jinsheng Wang Yangyang Wang Lei Wang Beidou Xi
Recently, biochar has emerged as a promising option for environmentally friendly remediation due to its cost-effectiveness, extensive surface area, porosity, and exceptional electrical conductivity. Biochar-based advanced oxidation procedures (BC-AOPs) have gained popularity as an effective approach to breaking down organic pollutants in aqueous environments. It is commonly recognized that the main reactive locations within BC-AOPs consist of functional groups found on biochar, which encompass oxygen-containing groups (OCGs), imperfections, and persistent free radicals (PFRs). Additionally, the existence of metallic components supported on biochar and foreign atoms doped into it profoundly impacts the catalytic mechanism. These components not only modify the fundamental qualities of biochar but also serve as reactive sites. Consequently, this paper offers a comprehensive review of the raw materials, preparation techniques, modification approaches, and composite catalyst preparation within the biochar catalytic system. Special attention is given to explaining the modifications in biochar properties and their impacts on catalytic activity. This paper highlights degradation mechanisms, specifically pathways that include radical and non-radical processes. Additionally, it thoroughly examines the importance of active sites as catalysts and the basic catalytic mechanism of BC-AOPs. Finally, the potential and future directions of environmental remediation using biochar catalysts and advanced oxidation processes (AOPs) are discussed. Moreover, suggestions for future advancements in BC-AOPs are provided to facilitate further development.
]]>Water doi: 10.3390/w16060876
Authors: Ying Li Liu Du Yung-Ho Chiu
Water scarcity is increasingly being recognized as a global concern. Sustainable Development Goal 6 (SDG-6) was established by the United Nations to address water resource governance within its sustainable development framework. This study employs the entropy weight method and a two-stage cyclical dynamic slacks-based measure (SBM) model to scientifically evaluate water resource utilization and governance across various regions in China. The findings reveal notable disparities in both the production and governance efficiency of water resources. Recognizing governance efficiency is crucial for promoting sustainable water resource utilization and socioeconomic development. The eastern, central, and western regions encounter unique challenges in attaining sustainability. The eastern region exhibits minimal potential for enhancing technical efficiency, necessitating interventions in management strategies and resource allocation. Conversely, the challenges in the central and western regions are more pronounced, demanding immediate implementation of new technologies and equipment. The data analysis in this study yields conclusions that offer targeted improvement recommendations to address disparities across China’s eastern, central, and western regions, and this is achieved by considering various developmental stages and regional contexts. These recommendations cover areas such as technical support, financial investment, and policy incentives, with the aim of enhancing the sustainable utilization of water resources in the country.
]]>Water doi: 10.3390/w16060874
Authors: Jafar Jafari-Asl Seyed Arman Hashemi Monfared Soroush Abolfathi
This study investigates the optimal and safe operation of pumping stations in water distribution systems (WDSs) with the aim of reducing the environmental footprint of water conveyance processes. We introduced the nonlinear chaotic honey badger algorithm (NCHBA), a novel and robust optimization method. The proposed method utilizes chaotic maps to enhance exploration and convergence speed, incorporating a nonlinear control parameter to effectively balance local and global search dynamics. Single-objective optimization results on a WDS show that NCHBA outperforms other algorithms in solution accuracy and convergence speed. The application of the proposed approach on a water network with two variable-speed pumps demonstrated a significant 27% reduction in energy consumption. Expanding our focus to the multi-objective optimization of pump scheduling programs in large-scale water distribution systems (WDSs), we employ the non-dominated sorting nonlinear chaotic honey badger algorithm (MONCHBA). The findings reveal that the use of variable-speed pumps not only enhances energy efficiency but also bolsters WDS reliability compared to the use of single-speed pumps. The results showcase the potential and robustness of the proposed multi-objective NCHBA in achieving an optimal Pareto front that effectively balances energy consumption, pressure levels, and water quality risk, facilitating carbon footprint reduction and sustainable management of WDSs.
]]>Water doi: 10.3390/w16060872
Authors: Melita Grant Juliet Willetts
Partnerships between water, sanitation and hygiene (WASH) and rights-holder organisations (RHOs) have become more common, important and impactful in the international development sector, and they have been driven by aligned agendas, mutual benefits and the pursuit of locally owned and inclusive development agendas. There are opportunities to broaden partnerships and coalitions to include climate change advocacy, adaptation and mitigation organisations given the increased focus on the links between WASH, resilience and climate change action. This article takes a first step in addressing the question: How can the experience of WASH, gender equality and climate organisation partnerships and coalitions in the Blue Pacific inform the WASH sector in its growing support of and investment in diverse partnerships in support of localism? We conducted a systematic scoping review to identify the literature on gender equality, WASH and climate change-related partnerships and coalitions in the Blue Pacific. Three key themes emerged from the systematic scoping review based on 23 studies published from 1996 to 2024. Firstly, partnerships and coalitions are part of a critical localism agenda, though care needs to be taken by potential partners and donors to understand and manage power dynamics between actors and organisations working within and across sectors. Secondly, a range of benefits and success factors have been documented on partnerships and coalitions in the Blue Pacific, including support for emerging leadership, leveraging policy outcomes, facilitating learning and the sharing of frameworks and tools between partners. Thirdly, like all parts of the community and governance ecosystem, gender dynamics and social norms inform and influence partnerships and coalitions. At the same time, partnerships are important for informing and driving gender equality and inclusion at the local and regional levels including within the WASH sector. This article is useful for local actors, donors and civil society organisations wishing to pursue the mutually beneficial goals of WASH, gender equality, climate change action and localisation in the Blue Pacific.
]]>Water doi: 10.3390/w16060873
Authors: Jingjiang Xiao Haiping Long Xuemei He Guoyu Chen Tao Yuan Yi Liu Qiaoling Xu
In order to treat phosphorus-containing wastewater and realize the resource utilization of wetland plant residues, biochar was prepared by the pyrolysis of canna aquatic plant waste at 700 °C, and the adsorption characteristics of phosphorus by MgO-modified biochar (MBC) were explored. The main results are as follows: the adsorption capacity of the MBC was eight times that of unmodified biochar (BC), and the adsorption capacity was up to 244 mg/g. The isothermal adsorption data were consistent with the Langmuir equation, which indicates monolayer adsorption. The functional groups changed little before and after the modification, but a new diffraction peak appeared after the modification. Compared with the standard card, it was suggested that there were MgO crystals with a higher purity. SEM images showed that the BC had a smooth surface, an obvious pore structure, and a thin pore wall, while the MBC had a rough surface and a layered structure, which can provide more adsorption sites for phosphate adsorption. In addition, an XPS analysis showed that Mg3(PO4)2 crystals appeared on the surface of the MBC after adsorption. The mechanism analysis showed that MgO is an important substance for MBC to adsorb phosphorus, and electrostatic adsorption and complex precipitation play key roles. In the test to verify the removal of actual phosphorus-containing wastewater by MBC, it was found that the removal rates for wastewater with 2.06 mg/L and 199.8 mg/L of phosphorus by MBC were as high as 93.4–93.9% and 99.2–99.3%, respectively. MBC can be used as an efficient adsorbent for phosphorus removal.
]]>Water doi: 10.3390/w16060871
Authors: P. A. Mikael Hedberg J. Gunnar I. Hellström Anders G. Andersson Patrik Andreasson Robin L. Andersson
Measurements of mass flow through a three-outlet spillway modeled after a scaled-down spillway were conducted. The inlet and channel leading up to the outlets were placed to lead the water toward the outlet at an angle. With this, measurements of the water level at three locations were recorded by magnetostrictive sensors. The volumetric flow rates for each individual outlet were recorded separately to study the differences between them. Additionally, Acoustic Doppler Velocimetry was used to measure water velocities close to the outlets. The conditions changed were the inlet volume flow rate and the flow distribution was measured at 90, 100, 110, and 200 L per second. Differences between the outlets were mostly within the error margin of the instruments used in the experiments with larger differences shown for the 200 L test. The results produced together with a CAD model of the setup can be used for verification of CFD methods. A simulation with the k-epsilon turbulence model is included and compared to earlier experiments and the new experimental results. Larger differences are seen in the new experiments. Differing inlet conditions are assumed as the principal cause for the differences seen.
]]>Water doi: 10.3390/w16060870
Authors: S. Sayanthan Hassimi Abu Hasan Siti Rozaimah Sheikh Abdullah
Floating aquatic macrophytes have a high level of proficiency in the removal of various contaminants, particularly nutrients, from wastewater. Due to their rapid growth rates, it is imperative to ensure the safe removal of the final biomass from the system. The ultimate macrophyte biomass is composed of lignocellulose and has enhanced nutritional and energy properties. Consequently, it can serve as a viable source material for applications such as the production of bioenergy, fertilizer and animal feed. However, its use remains limited, and in-depth studies are scarce. Here, we provide a comprehensive analysis of floating aquatic macrophytes and their efficacy in the elimination of heavy metals, nutrients and organic pollutants from various types of wastewater. This study offers a wide-ranging scrutiny of the potential use of plant biomasses as feedstock for bioenergy generation, focusing on both biochemical and thermochemical conversion processes. In addition, we provide information regarding the conversion of biomass into animal feed, focusing on ruminants, fish and poultry, the manufacture of fertilizers and the use of treated water. Overall, we offer a clear idea of the technoeconomic benefits of using macrophytes for the treatment of wastewater and the challenges that need to be rectified to make this cradle-to-cradle concept more efficient.
]]>Water doi: 10.3390/w16060869
Authors: Meryem Ayach Hajar Lazar Christel Lamat Abderrahim Bousouis Meryem Touzani Youssouf El Jarjini Ilias Kacimi Vincent Valles Laurent Barbiero Moad Morarech
The number and diversity of groundwater bodies (GWBs) in large French administrative regions pose challenges to their monitoring and protection by regional health agencies. To overcome this obstacle, we propose, for the Auvergne-Rhône-Alpes region (about 70,000 km2), a grouping of GWBs into homogeneous groups based on the sources of variability within a large dataset of groundwater physico-chemical and bacteriological characteristics (8078 observations and 13 parameters). This grouping involved a dimensional reduction in the data hyperspace by principal component analysis (PCA) and a clustering based on the mean values of each GWB on the factorial axes. The information lost when clustering from the sample point scale to the GWB scale and then to that of the GWB group was quantified by analysis of variance and showed that grouping GWBs is accompanied by a small loss of information. A discriminant analysis confirmed the high spatial and temporal variability within the dataset, as well as the effectiveness of the proposed method for establishing homogeneous sets. Some roadmaps for more targeted monitoring of water resources were briefly proposed.
]]>Water doi: 10.3390/w16060868
Authors: Yan Zhang Bingfei Chu Tianming Huang Shengwen Qi Michael Manga Huai Zhang Bowen Zheng Yuxin Zhou
Carbon geological storage (CGS) is an important global practice implemented to mitigate the effects of CO2 emissions on temperature, climate, sea level, and biodiversity. The monitoring of CGS leakage and the impact of storage on hydrogeological properties is important for management and long-term planning. In this study, we show the value of passive monitoring methods based on measuring and modeling water-level responses to tides. We review how monitoring can be used to identify time-varying horizontal and vertical permeabilities as well as independently detect time-varying fracture distribution in aquifer–caprock systems. Methods based on water-level responses to Earth tides are minimally invasive, convenient, economic (since they use existing groundwater wells), and time-continuous. We show how measurements can be used to detect aquifer leakage (caprock confinement) and the distribution of surrounding faults and fractures, which are the two most important unsolved quantities in assessing geological CO2 storage strategies.
]]>Water doi: 10.3390/w16060867
Authors: Jinming Chen Xiao Yang Haiya Dao Haowen Gu Gang Chen Changshu Mao Shihan Bai Shixiang Gu Zuhao Zhou Ziqi Yan
Water, soil, and heat are strategic supporting elements for human survival and social development. The degree of matching between human-land-water-heat elements directly influences the sustainable development of a region. However, the current evaluation of the matching of human-land-water-heat elements overlooks the influence of elevation factors on the matching results, especially evident in mountainous areas. Taking the Yunnan Plateau with distinctive mountainous features as the research subject, divided into 11 elevation ranges, the Lorenz Gini coefficient, asymmetry coefficient, matching distance, and imbalance index are used to assess the spatial matching and balance of human-land-water-heat elements. A projection tracing model is employed to analyze its water resource carrying capacity. Analyses revealed that the Gini coefficient of monthly precipitation from the 1950s to 2022 on the Yunnan Plateau increases with increasing latitude, whereas the correlation with elevation is notably lower. The asymmetry coefficient increases gradually from west to east with change in longitude. The mismatch of the human–land–water–heat system in regions at different elevations is in the order 1800–2000 m > 2000–2200 m > 1400–1600 m > 800 m > other areas. The matching of the human–land–water–heat system in different wet–dry years and seasons also fluctuates with elevation, resulting in serious seasonal drought and water shortage problems in mountainous areas with elevations of 1200–1600, 1800–2000 m, and >2600 m. The spatial equilibrium of temperature and precipitation in regions of different elevations is best, followed by that of cultivated land, while that of the population is the worst. The Gini coefficients for different water cycle processes of precipitation, surface runoff, and regulating storage capacity for water supply continue to increase. Specifically, the Gini coefficient of industrial water supply is the highest, reaching 0.576, and that of agricultural irrigation is the lowest (0.424). Through artificial regulation of lake and reservoir water, seasonal changes in the demand for agricultural irrigation water are offset to achieve a demand–supply balance and matching of land and water resources. The water resource capacity of different elevation ranges is evenly underloaded. However, the potential of the water resource capacity varies obviously with elevation in the order 2000–2200 m < 1800–2000 m < 1600–8000 m < 1400–1600 m < other areas. It appears that the greater the human–land–water–heat system mismatch, the smaller the regional potential of the water resource capacity.
]]>Water doi: 10.3390/w16060866
Authors: Qianwen Ye Cuicui Hou Qiang Wang Changjun Gao Kay Stefanik Feng Li Bingbing Jiang
For decades in China, carbon neutrality policies have spurred the establishment of northern margin mangroves as artificial blue carbon ecosystems. However, there has been limited research on the impact of plantation and invasion on the stocks and sources of soil carbon and nitrogen in rehabilitated coastal wetlands. Non-native Kandelia obovata afforestation began on Ximen Island, Zhejiang, China, where Spartina alterniflora invasion had also occurred decades ago. Soil cores were collected from both mangrove and salt marsh habitats with depths from 0 to 50 cm and were analyzed for total carbon (TC), soil organic carbon (SOC), total nitrogen (TN), and the isotope of carbon and nitrogen in sediments. The results indicated that there were no significant differences in the TC, SOC, and C/N ratio between the K. obovata and the S. alterniflora, but there were significant differences in TN, isotope δ13C, and δ15N. The SOC content of both ecosystems in the 0–20 cm layer was significantly higher than that in the 30–50 cm layer. Our study has shown that the main sources of carbon and nitrogen for mangroves and salt marshes are different, especially under the impact of external factors, such as tidal waves and aquaculture. These findings provide insight into the ecological functioning of subtropical coastal wetlands and an understanding of the biogeochemical cycles of northern margin mangrove ecosystems.
]]>Water doi: 10.3390/w16060865
Authors: Matthew G. Montgomery Miles B. Yaw John S. Schwartz
Probabilistic risk methods are becoming increasingly accepted as a means of carrying out risk-informed decision making regarding the design and operation policy of structures such as dams. Probabilistic risk calculations require the quantification of epistemic and aleatory uncertainties not investigated through deterministic methodologies. In this hydrological study, a stochastic sampling methodology is employed to investigate the joint failure probability of three dams in adjacent similarly sized watersheds within the same hydrologic unit code (HUC) 6 basin. A probabilistic flood hazard analysis (PFHA) framework is used to simulate the hydrologic loading of a range of extreme precipitation events across the combined watershed area of the three studied dams. Precipitation events are characterized by three distinct storm types influential in the Tennessee Valley region with implications for weather variability and climate change. The stochastic framework allows for the simulation of hundreds of thousands of spillway outflows that are used to produce empirical bivariate exceedance probabilities for spillway discharge pairs at selected dams. System response curves that indicate the probability of failure given spillway discharge are referenced for each dam and applied to generate empirical bivariate failure probability (joint failure probability) estimates. The stochastic simulation results indicate the range of spillway discharges for each pair of dams that pose the greatest risk of joint failure. The estimate of joint failure considering the dependence of spillway discharges between dams is shown to be three to four orders of magnitude more likely (7.42 × 102 to 5.68 × 103) than estimates that assume coincident failures are the result of independent hydrologic events.
]]>Water doi: 10.3390/w16060864
Authors: Will L. Varela Neal D. Mundahl David F. Staples Rachel H. Greene Silas Bergen Jennifer Cochran-Biederman Cole R. Weaver
Rivers across the globe experience and respond to changes within the riparian corridor. Disturbance of the riparian corridor can affect warmwater, intermediate, and coldwater streams, which can negatively influence instream physical structure and biological communities. This study focused on assessing the influence of the riparian habitat on instream structure within the Whitewater River, a coldwater stream system within an agricultural watershed in southeastern Minnesota, USA. To understand the influence of the riparian zone on the physical instream habitat, twenty variables (riparian, n = 9; instream, n = 11) were measured at 57 sites across three forks of the Whitewater using a transect method every 10 m across a 150 m reach. We used a modified Wentworth scale approach to assess coarse and fine substrates to describe habitat conditions. Canonical correlation detected significant associations between riparian and instream variables across the river forks, and indicated that wider riparian buffers, more bank grass and shrubs, longer overhanging vegetation, limited bare soil, and more rocks on banks were significantly associated with increased instream cover, high levels of coarse substrates with reduced embeddedness, increased pool habitats, and reduced fine sediments. In contrast, excessive fine sediments, lack of riffle habitat, reduced coarse substrates, and high width to depth ratios indicative of an impaired instream habitat were associated with narrow riparian buffers and high percentages of bare soil on banks. Riparian corridors have the capacity to enhance and protect physical instream habitats and overall ecosystem health when managed properly. Wide, grassy riparian corridors with stable banks, overhanging vegetation, and limited shade from trees should protect and/or enhance the instream physical habitat, providing the structural diversity favored by aquatic communities. We recommend revising the current Best Management Practices to include monitoring for impairments in the riparia, while promoting and developing good land stewardship with private landowners which can be effective in improving river ecosystems in agricultural settings.
]]>Water doi: 10.3390/w16060863
Authors: Neal D. Mundahl Erik D. Mundahl
Suspended and deposited sediments in streams can interfere with filter-feeding caddisfly larvae by reducing feeding sites and feeding efficiency, potentially lowering the densities, growth rates, and secondary production of an important trout prey. We conducted field studies at multiple stream sites with differing suspended-sediment loads, and a laboratory study was conducted under controlled conditions; together, these were designed to examine the role of suspended sediments in the population dynamics and behavior of Brachycentrus occidentalis (Trichoptera: Brachycentridae) larvae in a Minnesota, USA, trout stream. Stream sites that had elevated turbidities and elevated levels of suspended sediments also had significantly more fine bottom substrates and higher substrate embeddedness. In addition, Brachycentrus densities were reduced, growth rates were slower, secondary production was reduced, and the overall benthic macroinvertebrate taxa richness was lowest at the site with the highest suspended-sediment loading. Colder water temperatures at one site also influenced Brachycentrus production. In 24 h laboratory studies conducted in recirculating aquaria, the feeding activities of Brachycentrus larvae were reduced and their positioning altered under high turbidities (500 nephelometric turbidity units, NTU) relative to low turbidities (50 NTU or lower). High suspended-sediment loads have adversely affected filter-feeding caddisfly larvae by embedding and burying preferred coarse feeding substrates, altering their feeding positions and movements during the highest flows, and potentially impacting densities, growth rates, and secondary production.
]]>Water doi: 10.3390/w16060862
Authors: Shuo Gao Xirui Kang Yaping Li Jinpeng Yu Hui Wang Hong Pan Quangang Yang Zhongchen Yang Yajie Sun Yuping Zhuge Yanhong Lou
Cadmium (Cd) water pollution threatens environmental systems and human health. Adsorption is the preferred method for purifying water bodies polluted by Cd, and the development of effective adsorption materials is critical. The performance of original phosphate rock powder (PRP) as an adsorption medium for purifying water bodies polluted by Cd was compared with that of phosphate rock powder modified with fulvic acid, chitosan, MnO2, and sulfhydryl, respectively, and their appearance and adsorption properties were investigated. The surface structures of all modified powders were rougher than the original, and their functional groups were richer. The greatest Cd2+ adsorption capacity, 1.88 mg g−1, was achieved with chitosan-modified PRP (CMPRP). This was 106.59% greater than that of PRP. The capacities of fulvic acid and MnO2 were 15.38% and 4.40% greater than that of the original, respectively. When the fulvic acid-modified PRP, CMPRP, and manganese dioxide PRP reached adsorption equilibrium, the removal rates of Cd2+ were 51.86%, 93.26%, and 46.70%, respectively. Moreover, the removal rate of Cd2+ by CMPRP was 104.43% higher than that of PRP. The main Cd2+ adsorption mechanisms for the MPRPs were electrostatic interactions, ion exchange, co-precipitation, and complexation. Moreover, the processing of the phosphate rock powder was straightforward, harmless to the environment, and could be effectively used for the removal of Cd. These results show that CMPRP is promising as a new adsorption material to treat Cd-contaminated water.
]]>Water doi: 10.3390/w16060861
Authors: Hao Wang Yejiao Wang Fujie Jin
The swelling-shrinkage behavior of expansive soils under climate changes will cause the crack development, which can be destructive of expansive soil slopes. This study investigated the effect of drying/wetting cycles on the stability of an expansive soil slope using the discrete element method (DEM), in consideration of the crack development induced by climate changes. The strength reduction method was adopted in the DEM calculations, which was coupled with the unsaturated seepage analysis given by the finite element method. The slope stability and the failure model of the slope after different times of wetting–drying cycles were analyzed, and the results were compared with those calculated by the limit equilibrium method and the finite element method. The results indicated that the failure pattern of the expansive soil slope was strongly influenced by the wetting–drying cycles. A shallow sliding surface of the expansive soil slope occurred after several wetting–drying cycles. Similarly, the safety factor of the expansive soil slope decreased gradually with the wetting–drying cycles. Considering the cracks’ evolution inside the expansive soil slope from the drying/wetting cycles, a shallower sliding surface with a smaller safety factor was obtained from the strength reduction method of the DEM, in comparison with the two conventional methods of the Limit equilibrium method and finite element method. Therefore, cracks play an essential role in the expansive soil slope stability. The strength reduction method of the DEM, which considers the cracks’ evolution during drying/wetting cycles, is more reliable.
]]>Water doi: 10.3390/w16060860
Authors: Xuanshuo Shi Zhongfeng Qiu Yunjian Hu Dongzhi Zhao Aibo Zhao Hui Lin Yating Zhan Yu Wang Yuanzhi Zhang
Remote sensing technology plays a crucial role in the rapid and wide-scale monitoring of water quality, which is of great significance for water pollution prevention and control. In this study, the downstream and nearshore areas of the Huaihe River Basin were selected as the study area. By utilizing spectral information from standard solution measurements in the laboratory and in situ water quality data matched with satellite spatiotemporal data, inversion models for total phosphorus (TP) and ammonia nitrogen (NH3-N) water quality parameters were developed. The validation results using field measurements demonstrated that the inversion models performed well, with coefficients of determination (R2) of 0.7302 and 0.8024 and root mean square errors of 0.02614 mg/L and 0.0368 mg/L for total phosphorus and ammonia nitrogen, respectively. By applying the models to Sentinel-2 satellite images from 2022, the temporal and spatial distribution characteristics of total phosphorus and ammonia nitrogen concentrations in the study area were obtained. The ammonia nitrogen concentration ranged from 0.05 to 0.30 mg/L, while the total phosphorus concentration ranged from 0.10 to 0.40 mg/L. Overall, the distribution appeared to be stable. The southern region of the Guan River estuary showed slightly higher water quality parameter concentrations compared to the northern region, while the North Jiangsu Irrigation Main Canal estuary was affected by the dilution of river water, resulting in lower concentrations in the estuarine area.
]]>Water doi: 10.3390/w16060858
Authors: Ran Luo Wei Li Jiayou Zhong Taotao Dai Jinfu Liu Xiaoliang Zhang Yuwei Chen Guiqing Gao
Dredging, adsorbent inactivation, and phytoremediation are commonly used to control internal nitrogen and phosphorus sediment loads in eutrophic still-water ecosystems, such as lakes and ponds. However, the effectiveness of these remediation techniques has not been verified for rivers, lakes, and reservoirs with large disturbances. In this study, a calcium-loaded clay granular adsorbent (CRB) was prepared as an alternative to commercial adsorbents, and an experiment was conducted on the ecological restoration effects of both dredging and adsorbent single treatments as well as combined treatments on eutrophic flowing water. The enhancement effect of phytoremediation on the above restoration techniques was investigated. The results indicated that CRB inactivation treatment reduced the phosphorus and turbidity of the water by 63% and 80%, respectively and increased the total nitrogen and permanganate index (CODMn) by 25% and 101% before phytoremediation, respectively compared to the control group. There were no significant differences in the nutrient indexes of the sediment and water between the dredging treatment and the control group, but dredging enhanced the effect of the CRB treatment. Compared with the CRB treatment, the total nitrogen and CODMn of water in the dredging and combined CRB treatments decreased by 13% and 15%, respectively. Phytoremediation significantly improved the effectiveness of the dredging and adsorbent treatments, both individually and in combination. Additionally, there were notable differences in the growth rates of the submerged plants and the contents of different phosphorus speciation among the plant species. Selecting suitable plant species is recommended when implementing phytoremediation methods. This study highlights that the combination of multiple restoration techniques is effective for eutrophic flowing water. The results provide a guide for the ecological restoration of flowing water.
]]>Water doi: 10.3390/w16060859
Authors: Mustafa Erkan Turan Tulin Cetin
Sewer systems are a component of city infrastructure that requires large investment in construction and operation. Metaheuristic optimization methods have been used to solve sewer optimization problems. The aim of this study is to investigate the effects of network size on metaheuristic optimization algorithms. Cuckoo Search (CS) and four versions of Grey Wolf Optimization (GWO) were utilized for the hydraulic optimization of sewer networks. The purpose of using different algorithms is to investigate whether the results obtained differ depending on the algorithm. In addition, to eliminate the parameter effect, the relevant algorithms were run with different parameters, such as population size. These algorithms were performed on three different-sized networks, namely small-sized, medium-sized, and large-sized networks. Friedman and Wilcoxon tests were utilized to statistically analyze the results. The results were also evaluated in terms of the optimality gap criterion. According to the results based on the optimality gap, the performance of each algorithm decreases as the network size increases.
]]>Water doi: 10.3390/w16060857
Authors: Lijun Jin Changsheng Yan Baojun Yuan Jing Liu Jifeng Liu
The source area of the Yellow River (SAYR) in China is an important water yield and water-conservation area in the Yellow River. Understanding the variability in rainfall and flood over the SAYR region and the related mechanism of flood-causing rainfall is of great importance for the utilization of flood water resources through the optimal operation of cascade reservoirs over the upper Yellow River such as Longyangxia and Liujiaxia, and even for the prevention of flood and drought disasters for the entire Yellow River. Based on the flow data of Tangnaihai hydrological station, the rainfall data of the SAYR region and NCEP-NCAR reanalysis data from 1961 to 2020, three meteorological conceptual models of flood-causing rainfall—namely westerly trough type, low vortex shear type, and subtropical high southwest flow type—are established by using the weather-type method. The mechanism of flood-causing rainfall and the corresponding flood characteristics of each weather type were investigated. The results show that during the process of flood-causing rainfall, in the westerly trough type, the mid- and high-latitude circulation is flat and fluctuating. In the low vortex shear type, the high pressures over the Ural Mountains and the Okhotsk Sea are stronger compared to other types in the same period, and a low vortex shear line is formed in the west of the SAYR region at the low level. The rain is formed during the eastward movement of the shear line. In the subtropical high southwest flow type, the low trough of Lake Balkhash and the subtropical high are stronger compared to other types in the same period. Flood-causing rainfall generally occurs in areas with low-level convergence, high-level negative vorticity, low-level positive vorticity, convergence of water vapor flux, a certain amount of atmospheric precipitable water, and low-level cold advection. In terms of flood peak increment and the maximum accumulated flood volume, the westerly trough type has a long duration and small flood volume, and the low vortex shear type and the subtropical high southwest flow type have a short duration and large flood volume.
]]>Water doi: 10.3390/w16060856
Authors: Abdul Qayoom Landar Taj Muhammad Jahangir Muhammad Yar Khuhawar Muhammad Farooque Lanjwani Faheem Yar Khuhawar
Sanghar District is located in the central part of Sindh Province and shares a boarder with India to the east. This work examines the water quality of the groundwater of three subdistricts, Sanghar, Khipro, and Jan Nawaz Ali, mostly used for human consumption, cattle farming, and irrigation. A total of 74 representative samples were collected and analyzed for 26 different parameters, including anions, cations, trace, and toxic elements. The total dissolved salts (TDSs) contained in 41 samples (55.4%), the major cations, K, Na, Mg, and Ca, in 44.6–93.2% of samples, and the major anions, Cl, HCO3, and SO4, in 68.6–81.0% of samples were within the permissible guidelines of the World Health Organization (WHO). The samples containing elements Cr (24.0%), Pb (29.7%), Ni (39.2%), Cd (40.5%), As (10.8%), and F (39.18%) were above the permissible limits of the WHO. The groundwater samples were examined for water quality index (WQI), contamination index (Cd), chronic daily intake indices (CDIs), hazard quotient indices (HQ), principal component analysis (PCA), piper diagrams, Gibbs diagrams, and cluster analysis to ascertain nature of the groundwater present in the study area. The samples were also examined for suitability for irrigation by sodium percentage (Na%), sodium adsorption ratio (SAR), Kelly’s index (KI), permeability index (PI), and Wilcox diagrams. Samples in the range of 0 to 58.33% were inappropriate for irrigation.
]]>Water doi: 10.3390/w16060855
Authors: Irina Stefanović Ratko Ristić Nada Dragović Milutin Stefanović Nada Živanović Jelena Čotrić
The aim of this research was to analyze the impact of implemented erosion control works (ECW) on soil erosion intensity in the watershed of the Ćelije reservoir (Rasina River) in the period between 1968 and 2022. The Erosion Potential Method was used to calculate the annual gross erosion (W), sediment transport (G), and erosion coefficient (Z) in the study area. As a result of the performed ECW there was a general decreasing trend in the intensity of soil erosion processes in the last 54 years. The specific annual gross erosion was 1189.12 m3/km−2/year−1 in 1968, while in 2022 it was 554.20 m3/km−2/year−1. The specific sediment transport was 540.18 m3/km−2/year−1 in 1968 and 253.55 m3/km−2/year−1 in 2022. Due to the changes in the intensity of erosion processes, the specific annual gross erosion decreased by 634.92 m3/km−2/year−1 and the specific sediment transport decreased by 286.63 m3/km−2/year−1. The erosion coefficient was reduced from Z = 0.62 to Z = 0.35. A dependence between the slope of siltation and the natural bed slope was defined. The results show a significant correlation between erosion intensity and performed ECW, providing a basis for future watershed management and defining a strategy for soil erosion control in the Ćelije reservoir watershed.
]]>Water doi: 10.3390/w16060854
Authors: Jiayu Huang Feng Diao Shifeng Ding Sen Han Pentti Kujala Li Zhou
In previous studies of ship–ice interactions, most studies focused on ship–level ice interactions, overlooking potential rafted ice conditions in extreme ice conditions. The purpose of this study is to develop a numerical model for predicting ship resistance in rafted ice regions. Numerical modeling of rafted ice was carried out using preset grid cells. By comparing the model test results, the accuracy and reliability of the numerical model are verified. On this basis, we undertook the analysis of the impacts of different ice thicknesses, ship speeds, bending strengths, and crushing strengths on the ice resistance of ships under level and rafted ice conditions. The results show that the ice resistance of ships is significantly higher than that of rafted ice under the condition of level ice; however, level ice and rafted ice have different effects on ship ice resistance. Compared with level ice, the ice resistance of ships navigating in rafted ice is more concentrated. The findings of the present research can serve as a technical reference for studies focused on predicting ship resistance in rafted ice regions.
]]>Water doi: 10.3390/w16060853
Authors: Ha-Kyung Kim In-Hwan Cho Eun-A Hwang Byung-Hun Han Baik-Ho Kim
This paper reviews the evolution and integration of diatom-based water quality assessments with environmental DNA (eDNA) techniques for advancing river ecosystem health evaluations. Traditional methods, relying on microscopy and diatom indices, have significantly contributed to our understanding of aquatic ecosystems but face challenges such as the need for taxonomic expertise and the labor-intensive nature of sample collection. Recent advancements in molecular biology, particularly eDNA analysis, offer opportunities to overcome these limitations, providing more accurate and comprehensive assessments. This study highlights the benefits of combining traditional microscopy with modern molecular techniques, enhancing the precision and efficiency of water quality evaluations. By addressing the challenges of standardizing methods and improving species identification through comprehensive reference libraries and advanced bioinformatics tools, this integrated approach aims to refine and advance the effectiveness of diatom-based strategies in monitoring and managing river health amidst environmental changes.
]]>Water doi: 10.3390/w16060852
Authors: Yawei Ning Minglei Ren Shuai Guo Guohua Liang Bin He Xiaoyang Liu Rong Tang
Multi-objective reservoir operation of reservoir flood control involves numerous factors and complex model solving, and exploring effective methods for solving the operation models has always been a hot topic in reservoir optimization operation research. The Multi-Objective Ant Lion Algorithm (MOALO) is an emerging heuristic intelligent optimization algorithm, but it has not yet been applied in reservoir optimization operation. Testing the effectiveness of this method on multi-objective reservoir scheduling and further improving the optimization performance of this method is of great significance for enhancing the overall benefits of reservoir operation. In this study, MOALO is applied to the optimal scheduling of reservoir flood control. To increase the search efficiency of MOLAO, the advanced MOALO method (AMOLAO) is proposed by reconstructing the search distribution in MOALO using a power function. Taking the Songshu Reservoir and Dongfeng Reservoir in the Fuzhou River Basin in Dalian City as an example, MOALO, AMOLAO, and other two traditional methods are applied for solving the multi-objective reservoir operation problem. Results show that the AMOALO method has high search efficiency, strong optimization ability, and good stability. AMOALO performs better than MOALO and the two traditional methods. The study provides an efficient method for solving the problems in multi-objective reservoir operation.
]]>Water doi: 10.3390/w16060851
Authors: Ryan Good David Nguyen Hossein Bonakdari Andrew Binns Bahram Gharabaghi
Predicting morphological adjustments in alluvial meandering streams remains a challenging task due to the complex nature of the governing inter-related dynamic flow and sediment transport processes. This difficulty is increased in streams with irregular single-channel planform geometries, such as skewed meanders, where the meander apex is shifted in either the up-valley or down-valley direction relative to the meander centroid. Research in confined bank flume experiments has shown that the geometry difference affects flow characteristics and streambed development. The present study extends upon these findings by being the first to investigate the effects of skewness orientation in a wide-channel flume with a fully unconfined bed and banks. Three experiments were completed with an up-valley skewed, a down-valley skewed, and a non-skewed symmetrical channel, using well-sorted coarse sand and no sediment feed. The results had some variabilities in erosion and magnitude of morphological developments due to initial experimental conditions, but our analysis of the bedform positioning showed notable similarities and differences between the geometries. Bedforms typically formed upstream of the apex, with differences in their stream-wise direction extents. This research highlights how channel width-to-depth ratio and bank erodibility significantly impact river evolution, offering new insights into the dynamics of skewed meandering river channels. This study is a novel step towards a better understanding of skewed meandering rivers in unconfined alluvial channels and highlights opportunities for further research.
]]>Water doi: 10.3390/w16060850
Authors: Gao Huang Chengjun Qiu Mengtian Song Wei Qu Yuan Zhuang Kaixuan Chen Kaijie Huang Jiaqi Gao Jianfeng Hao Huili Hao
Cavitation is typically observed when high-pressure submerged water jets are used. A composite nozzle, based on an organ pipe, can increase shear stress on the incoming flow, significantly enhancing cavitation performance by stacking Helmholtz cavities in series. In the present work, the flow field of the composite nozzle was numerically simulated using Large Eddy Simulation and was paired with the response surface method for global optimizing the crucial parameters of the composite nozzle to examine their effect on cavitation behavior. Utilizing peak gas-phase volume percent as the dependent variable and the runner diameter, Helmholtz chamber diameter, and Helmholtz chamber length as independent variables, a mathematical model was constructed to determine the ideal parameters of the composite nozzle through response surface methodology. The optimized nozzle prediction had an error of only 2.04% compared to the simulation results, confirming the accuracy of the model. To learn more about the cavitation cloud properties, an experimental setup for high-pressure cavitation jets was also constructed. Impact force measurements and high-speed photography tests were among the experiments conducted. The simulated evolution period of cavitation cloud characteristics is highly consistent with the experimental period. In the impact force measurement experiment, the simulated impact force oscillates between 256 and 297 N, and the measured impact force oscillates between 260 N and 289 N, with an error between 1.5% and 2.7%. The simulation model was verified by experimental results. This study provides new insights for the development of cavitation jet nozzle design theory.
]]>Water doi: 10.3390/w16060849
Authors: Bojana Tubić Stefan Andjus Katarina Zorić Božica Vasiljević Katarina Jovičić Jelena Čanak Atlagić Momir Paunović
The aim of the study was to test the significance of the EPT index in the water quality assessment of three types of water bodies in hilly and mountainous region of Serbia. The aquatic macroinvertebrate community was dominated by the group of insects, of which 95 taxa represent the EPT group. We compared the obtained values of biological indices used for the assessment of water quality according to the national legislation with the overall status assessment represented by the ecological quality classes (EQC). The results of the Spearman correlation test showed a negative correlation of EQC with the EPT index, BMWP score, H′, total number of taxa and number of sensitive taxa, while a positive correlation was observed for the values of SI and Tubificinae %. The values of EQC and biological indices were subjected to principal component analysis (PCA). The results showed that the parameters that contributed most to the differences were the EPT index, the BMWP score and the number of sensitive taxa. The results indicate that the EPT index is an excellent indicator of changes in water quality and an important tool for the ecological categorization of water bodies in mountain regions.
]]>Water doi: 10.3390/w16060848
Authors: Xinyu Wang Hossein Ghanizadeh Shoaib Khan Xiaodan Wu Haowei Li Samreen Sadiq Jiayin Liu Huimin Liu Qunfeng Yue
Removing organic pollutants from wastewater is crucial to prevent environmental contamination and protect human health. Immobilized enzymes are increasingly being explored for wastewater treatment due to their specific catalytic activities, reusability, and stability under various environmental conditions. Peroxidases, such as horseradish peroxidase (HRP) and myoglobin (Mb), are promising candidates for immobilized enzymes utilized in wastewater treatment due to their ability to facilitate the oxidation process of a wide range of organic molecules. However, the properties of the carrier and support materials greatly influence the stability and activity of immobilized HRP and Mb. In this research, we developed immobilized HRP and Mb using support material composed of sodium alginate and CaCl2 as carriers and glutaraldehyde as a crosslinking agent. Following this, the efficacy of immobilized HRP and Mb in removing aniline, phenol, and p-nitrophenol was assessed. Both immobilized enzymes removed all three organic pollutants from an aqueous solution, but Mb was more effective than HRP. After being immobilized, both enzymes became more resilient to changes in temperature and pH. Both immobilized enzymes retained their ability to eliminate organic pollutants through eight treatment cycles. Our study uncovered novel immobilized enzyme microspheres and demonstrated their successful application in wastewater treatment, paving the way for future research.
]]>Water doi: 10.3390/w16060847
Authors: Ishanka Prabhath Wimalaweera Yuansong Wei Tharindu Ritigala Yawei Wang Hui Zhong Rohan Weerasooriya Shameen Jinadasa Sujithra Weragoda
The efficiency of magnetic seed coagulation (MSC) with pH adjustment by NaOH and Ca(OH)2 as a pretreatment for high-strength natural rubber industrial wastewater (NRIWW) was compared in this study. The high content of suspended solids (SSs) and other inhibitory substances of NRIWW is a primary issue which affects its subsequent secondary and tertiary treatment processes. The MSC process with polyaluminum chloride (PAC), anionic polymer (polyacrylamide—PAM)), and magnetic seeds (MS) (ferric oxide (Fe3O4)) was proven to be a cost-effective pretreatment of NRIWW, and Ca(OH)2 showed improved pretreatment performance, with turbidity, COD, and TSS removals of 95%, 56%, and 64%, respectively. Sedimentation was enhanced from 30 min by conventional coagulation to less than 5 min by the MSC. The organic components of NRIWW reacted with MS to generate Fe–OH/Fe–OH+ linkages through processes of surface complexing and hydrogen bonding. According to fractal analysis, the MSC process optimized with Ca(OH)2 produces less complex flocs that are uniform and densely packed. Additionally, MS served as an adsorbent and promoted the development of magnetic flocs by boosting their density and size. MSC with pH adjustment by Ca(OH)2 presents a robust and cost-effective pretreatment process for NRIWW.
]]>Water doi: 10.3390/w16060846
Authors: Zhongao Yang Xiaohua Ding Xin Liu Abdoul Wahab Zhongchen Ao Ya Tian Van Son Bang Zhaoxi Long Guodong Li Penglin Ma
The instability of geological slopes in mining environments poses a significant challenge to the safety and efficiency of operations. Waste Dump#2 at the Ziluoyi Iron Mine in China is a notable case study that highlights the challenges associated with sizable base slopes and large step heights. To address hidden hazards in the mine and the above issues, an inclusive investigation is carried out to examine the physical and mechanical properties of the soil–rock slope through indoor testing and analyze the deformation mechanisms of the slope using numerical simulations, taking various factors into account. The study reveals that the stability of Waste Dump#2 is deeply affected by weight, groundwater conditions, earthquake loading, and rainfall. To this end, the cohesion and internal friction parameters of the soil–rock slope are first determined through direct shear tests, which show a cohesion of 6.215 kPa at the top of the slope and an internal friction angle of 34.12°. By adopting GEO-SLOPE, 3D Mine, and AutoCAD software, stability calculations of the slope are performed, which give stability coefficients of 1.547 under normal conditions, 1.276 in rainfall, and 1.352 in seismic conditions. These results meet safety standards and ensure the safe and efficient operation of the mine.
]]>Water doi: 10.3390/w16060845
Authors: Defang Lu Yuejun Zheng Xianghui Cao Jiaojiao Guan Wenpeng Li Kifayatullah Khan
In recent decades, the water cycle process in the Loess Plateau has undergone drastic changes under the influence of anthropogenic disturbance and climate variability. The Loess Plateau has been greatly affected by human activities and climate change, and the dynamics of water balance and its key influencing factors remain unknown in this region. To deepen our understanding of water resource status in the Loess Plateau, we analyzed the dynamic changes in the hydrological cycle components and terrestrial water balance via remote sensing during the 2001–2020 period. Moreover, we also discussed the dominant factors affecting the terrestrial water balance. The results indicate that precipitation and ET exhibited increasing trends, with upward rates of 2.56 mm/yr and 5.27 mm/yr, respectively. Spatially, the annual average precipitation and ET showed increasing trends from the north to south. Precipitation in 62.05% of the entire region presented a significant upward trend, with a change rate of 0~2 mm/yr, and the annual change rate of ET in a range of 0~30 mm/year accounted for 89.12%. The runoff exhibited a fluctuating and significantly upward trend during the 2000–2022 period, with a change rate of 3.92 × 108 m3/yr, and was relatively large in the middle reach of the Yellow River. The annual average water consumption in the upper reach of the YRB presented a significant decreasing trend, with a downward rate of −0.06 × 108 m3/yr from 2001 to 2020, and yet it displayed a significant increasing trend in the middle and lower reaches of the YRB with the upward rate of 0.07~0.11 × 108 m3/yr. Based on the principle of water balance, the recharge amount was calculated at less than the discharge amount during the 2001–2020 period, and the difference between recharge and discharge is gradually expanding, with a change rate of −3.72 × 108 m3/yr. The spatial distributions of TWSC revealed that the eastern region was in an imbalanced state, while the western region was in a relatively balanced state. Terrestrial water balance changes were mainly affected by climate factors and human disturbance, and land use/cover change was the dominant factor. The results will be of great significance for optimizing water resource management and formulating various water-saving strategies in the Loess Plateau.
]]>Water doi: 10.3390/w16060844
Authors: Somayeh Emami Hossein Dehghanisanij
The recent problems of Lake Urmia (LU) are caused by extensive and complex socio-ecological factors that require a comprehensive approach to consider the relationships between users and identify failure factors at the basin level. For this purpose, an agent-based simulation model of farmers’ social interactions and economic interests (ABM) with various support scenarios and random supervision and training by the government agent is developed to evaluate its impact on independent farmers’ decision-making in the form of a complex adaptive system. Finally, a fault tree analysis (FTA) is created in the Cara-FaultTree 4.1. software to identify scenarios that lead to the non-development technology in irrigation management (non-DTIM) in the LU sub-basin. The assessment of the impact of government supervision and training revealed that the main causes of non-DTIM in the LU basin are a lack of demands from farmers and low awareness among residents of the basin, with failure probabilities of 0.90 and 0.86, respectively. Ultimately, the failure probability of the main event (non-DTIM) was 0.50. The paths of proper training and farmers’ requirements for sustainable agricultural water supply should become more stringent. The results confirm that appropriate measures to strengthen government supervision and training, as well as raise farmers’ awareness of the importance of long-term sustainability of water resources, can lead to greater resilience in the DTIM.
]]>Water doi: 10.3390/w16060843
Authors: Maria Perraki Vasilios Skliros Petros Mecaj Eleni Vasileiou Christos Salmas Ioannis Papanikolaou Georgios Stamatis
Sixteen surface (5) and groundwater (11) samples were collected from the south-eastern part of Attica, Greece, and analysed for physico-chemical parameters and microplastics (MPs) by optical microscopy and Raman microspectroscopy (RS). A total of 3399 particles were optically identified in all sixteen samples, ranging from only 16 particles/L in a sample from a deeper borehole to 513 particles/L in a sample from a shallow water well. They were then visually classified into eight categories based on their color, texture, size, reflectivity, shape, and general morphological properties. Raman microspectroscopy was performed on the particles on the filters and revealed four different types of MPs, namely polyethylene (PE, 35%), polypropylene (PP, 30%), polystyrene (PS, 10%), and polyethylene terephthalate (PET, 25%). The samples from the shallow phreatic aquifer contained more MPs than the samples from the deeper borehole, which contained fewer MPs and categories. This is to be expected, since the phreatic aquifer (a) is generally more contaminated, as it is close to human activities that generate MPs and its infiltration depth is only a few metres, which means that many microplastics can infiltrate at such shallow depths, and (b) it is exposed to the atmosphere, so they can also be suspended in the air. On the other hand, it is interesting to note that MPs, especially PET and PE, were detected in the borehole sample, suggesting that MPs can migrate to greater depths through water infiltration. Chemical analyses of the groundwater samples revealed high values of E.C., Ca2+, Mg2+, Cl−, and Na+, which indicate that seawater intrusion is taking place in the coastal aquifer system of the Erasinos basin. The increased concentrations of NO3− and PO43− also indicate the impact of agricultural activities.
]]>Water doi: 10.3390/w16060842
Authors: Fahad Alshehri Mark Ross
This hydrological study investigated a combined rating methodology tested on a 14,090 km2 area in Southwest Florida. The approach applied the Hydrological Simulation Program-Fortran (HSPF) over a 23-year period and was validated by 28 stream gauging stations. The regional hydrological complexity includes natural and agricultural areas, as well as extensive phosphate mining and urbanizing areas. This application is a novel and efficient methodology for generating stage–storage–discharge relationships using a geographic information system (GIS), empirical equations, and spreadsheets for 148,000 isolated and connected alluvial wetlands within the model domain. The validation metrics used to evaluate the applied methodology for populating the stage–storage–discharge relationship demonstrated the model effectiveness in simulating a range of hydrological events across various regions. For discharge prediction, the Nash–Sutcliffe efficiency values surpassed 0.7 at most stations, with an average of 0.67, and the average R squared was 0.74. This methodology, when applied, achieved a root-mean-square error of 4 m3/s for discharge prediction and 0.47 m for stage prediction. However, limitations emerged in simulating baseflow (low flows), highlighting the need for integrated modeling approaches to accurately capture groundwater–surface water interactions. The research provides an improved means for modeling regional water resources and lays the groundwork for enhanced hydrological modeling in watersheds with complex alluvial and isolated wetland systems.
]]>Water doi: 10.3390/w16060841
Authors: Lei Jiang Ziyue Zeng
Since the impoundment of the Three Gorges Project, the downstream hydrology and river dynamics have been modified. The Yichang–Chenglingji Reach (YCR), as a part of the mainstream of the Middle Yangtze River, has consequently been significantly scoured, which has resulted in stream trenching and section enlargements, without showing any obvious trend in flood level variation, however. This phenomenon can be caused by the increase in riverbed resistance due to river geomorphological change and bottomland vegetation development and the backwater effect of Dongting Lake. To investigate how these factors influence the flood water levels, this study analyzed the variations in the influencing factors based on observational data, theoretical analysis and mathematical modelling, including river channel scouring, riverbed resistance, and the influence of Dongting Lake backwater. Then, the impact of these factors on flood levels was evaluated, followed by a comparative analysis of the effects of various factors. The results show that both the flood backwater height (ΔZ) and the backwater influence range (L) are positively correlated with the outflow intensity (T) at the Chenglingji station. The backwater effect decreases gradually with increasing upstream distance, and the influence on the upstream reach can extend up to Shashi city. It was also indicated that the increase in riverbed resistance due to bottomland vegetation development and river geomorphology are dominant factors in inhibiting flood level declines in the YCR, while the backwater of Dongting Lake just affects local regions. This study can provide a better understanding of the flood level changes of the YCR and thus contribute to flood control and riverbank protection of the Yangtze River in the future.
]]>Water doi: 10.3390/w16060840
Authors: Yifan Lu Xihuan Sun Yongye Li Cheng Wang Siyuan Tao
It is of great significance to explore the flow velocity characteristics of piped cars when they are started under different loads. In this paper, the flow velocity characteristics of the water flow around a piped car when it is started in the straight pipe section are studied through physical experiments. The masses of the piped cars are 1.5 kg, 1.9 kg, and 2.3 kg, respectively. The results show that, with the increase in the load of the pipeline car, the axial flow velocity in the front section increases, the absolute values of radial flow velocity and circumferential flow velocity increase, and the gradient of flow velocity increases. The positive radial flow velocity and negative circumferential flow velocity regions increase, and the distribution of positive and negative radial flow velocities and circumferential flow velocities is obvious. The gradients of axial, radial, and circumferential flow velocities in the annular section all increase, and the contour spacing becomes smaller and more densely distributed. The absolute values of the radial and circumferential flow velocities increase. The regional demarcation of axial flow velocity in the rear section is more obvious, and the average value of axial flow velocity in the high-flow-velocity area behind the vehicle increases. Additionally, the gradient of flow velocity increases. The absolute values of radial velocity and circumferential velocity increase, the gradient of velocity increases, and the velocity distribution is obviously regional. This study supplements and improves the theoretical study of a piped car when it is started and has certain reference value for the research and application of the hydraulic transport technology of the barrel-loading pipeline.
]]>Water doi: 10.3390/w16060838
Authors: Talita Flores Dias Enedir Ghisi
The study and analysis of urban water consumption habits in different regions contribute to the development of strategies aimed at secure water reduction and distribution. Within this context, knowledge of global water availability and the analysis of factors that influence consumption in different regions in distinct situations become extremely important. Several studies have been carried out in a number of countries and describe different approaches. The objective of this article is to learn about the strategies used in water consumption forecast and analysis. Most of the studies analysed seek to understand the factors influencing consumption in different building types. When it comes to residential buildings, the number of residents and the influence of economic issues on water consumption have an important role in this matter. In this context, pieces of research present the use of awareness campaigns as a strategy towards water use reduction. As a contribution, this article presents a systemic view of the pieces of research conducted and their contribution to forecasting water consumption in different regions. In conclusion, one observes the importance of analysing the factors influencing water consumption in different regions and scenarios, such as during the COVID-19 pandemic. This article can help managers and researchers understand the main factors that influence water consumption and how this consumption takes place in different regions.
]]>Water doi: 10.3390/w16060839
Authors: Yehia Manawi Ayesha Ahmad Mosab Subeh Mohammad Hushari Sayed Bukhari Huda Al-Sulaiti
In the original publication [...]
]]>Water doi: 10.3390/w16060837
Authors: Ting Wang Maoshan Li Ming Gong Yuchen Liu Yonghao Jiang Pei Xu Yaoming Ma Fanglin Sun
This study investigated the convective weather features, precipitation microphysical characteristics, and water vapour transport characteristics associated with a southwest vortex precipitation event that occurred on the eastern edge of the Qinghai–Tibet Plateau, coinciding with a southwest vortex event, from 15 to 16 July 2021, using conventional observations of raindrop spectra, ERA5 reanalysis data, CMORPH precipitation data, and the HYSPLIT_v4 backward trajectory model. The findings aim to provide theoretical insights for improving the forecasting and numerical simulations of southwest vortex precipitation events. The findings revealed that the precipitation event induced by the southwestern vortex at Emeishan Station on 15–16 July 2021 was characterised by high rainfall intensity and significant precipitation accumulation. The raindrop spectrum exhibited a broad distribution with a notable bimodal structure. Both the Sichuan Basin and the Tibetan Plateau were dominated by the South Asian high pressure at higher altitudes, while a pronounced low-pressure system developed at mid and low altitudes within the basin, establishing a meteorological context marked by upper-level divergence and lower-level convergence. Throughout the event, notable vertical uplift velocities were recorded across the Sichuan Basin and Tibetan Plateau, along with distinct positive vorticity zones in the lower and middle strata of the Sichuan Basin, indicating that the atmosphere was in a state of thermal instability. The majority of moisture was in the mid and lower troposphere with evident convergence movements, which played a crucial role in the southwest vortex’s development. WRF numerical simulations of the Emeishan precipitation event more accurately modelled the weather conditions for this precipitation but tended to overestimate the level of precipitation. It was observed that the region around Emei Mountain primarily received moisture influx from the southern Bay of Bengal and the South China Sea, with moisture transport chiefly originating from the Sichuan Basin and in a south-westward trajectory.
]]>Water doi: 10.3390/w16060836
Authors: Jong Dae Do Sang Kwon Hyun Jae-Youll Jin Weon-Mu Jeong Byunggil Lee Yeon S. Chang
In this study, a swash-zone model, using Larson and Wamsley formula (LW07), was combined into the Telemac-2D model system to examine the performance of modeling swash-zone processes through comparisons with field observation data. The experimental site was the Haeundae Beach in South Korea where Typhoon Phanfone occurred in October 2014, and bathymetric surveys were performed before and after the typhoon. Hydrodynamic data were also measured to validate the modeled data. The performance of LW07 was tested by running the model in two modes, with and without LW07. First, the model was run to simulate the shoreline response to an imaginary coastal breakwater. The result showed a clear discrepancy between the two modes as the sediments were considerably cumulated behind the breakwater in the case with the swash-zone formula (LW07) in the wide range along the shoreline behind the breakwater, indicating that the sediments more actively and rapidly responded to the shadowing by the breakwater with LW07. The model was also run for a realistic case from August to October 2014, which included the typhoon’s period during 2–6 October. The results showed that the morphological changes at both ends of the beach in the swash zone were simulated with higher accuracy with LW07, supporting the effectiveness of LW07 in simulating the short-term morphological changes induced by the typhoon attack. In particular, the successful simulation of the sand accumulation at the end sides of the beach’s swash zone indicates that LW07 was effective in estimating not only the cross-shore transport but also longshore transport, which was likely due to the characteristics of LW07 that calculated sand transport in both directions. The enhanced modeling performance with LW07 was likely due to the adjustment of the sediment transport rate to the instantaneous changes in the local beach slope, which could successfully control the erosion/accretion process in the swash zone more realistically.
]]>Water doi: 10.3390/w16060835
Authors: Zia Madani David Natcher
The governance of the water, energy, and food (WEF) nexus is significant in the Arctic, where environmental changes are occurring at an accelerated pace, intensifying resource dynamics and geopolitical implications. Against the backdrop of a rapidly evolving Arctic landscape shaped by the global climate change, melting ice, and resource exploration, the WEF nexus emerges as a vital framework for understanding and addressing the region’s complex resource interdependencies. Nonetheless, legal research in this context is still in its early stages, and, specifically in the context of the Arctic, we did not find any such research. This study assesses a nexus approach to WEF in Arctic’s transdisciplinary and multifaceted environment from an international law perspective to address the intricate dynamics that shape the resilience and security of WEF resources in an increasingly interconnected and accessible Arctic. Our objective in this study is to introduce international law as an overarching network of international rules and principles, legal instruments, and relevant institutions as a starting point to address the WEF governance intricacies in the Arctic, facilitating the harmonization of diverse interests, ensuring equitable access to resources, and promoting sustainable development. We argue that international law constitutes the essential means to address a nexus approach to WEF and its issues and complexities in a transboundary context within the Arctic. By examining existing international legal frameworks applicable to the Arctic and related instruments, policies, journals, and other publications, this paper seeks to canvas how international law is in support of a nexus approach to WEF in this region.
]]>Water doi: 10.3390/w16060834
Authors: Donghai Yuan Hui Wang Chen Wang Chenling Yan Lili Xu Chunyang Zhang Jiazhuo Wang Yingying Kou
Intense climate change and rapid urbanization have increased the risk of urban flooding, seriously affecting urban economic and social stability. Enhancing urban flood resilience (UFR) has required a new solution to cope with urban flood disasters. In this study, taking Yingtan city as an example, a system of indicators for evaluating UFR was constructed, with 17 representative indicators, comprising three subsystems: socio-economic, ecological, and infrastructural. A hybrid model combining Fuzzy Analytic Hierarchy Process (FAHP), Entropy Weight Method (EWM), and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was applied, to develop an index-based measurement to compare and evaluate UFR, and Gray Relational Analysis (GRA) was used to discover the main factors affecting UFR. In addition, the natural discontinuous method was innovatively used to divide the UFR grade interval into levels, and the grade change was evaluated based on the TOPSIS method. The results showed that (1) From 2010 to 2022, the UFR in Yingtan City increased by 80.69%, and the factors affecting UFR were highly correlated with urban infrastructure development; however, the ecological resilience in the subsystem showed a fluctuating downward trend because of the influence of the surface area of lakes and rivers; (2) The grades of UFR for Yingtan City increased from Level III (2010 and 2016) to Level IV (2022), with local financial expenditures and the age structure of the population being the main factors currently limiting the development of UFR. The study provides a theoretical basis for the construction of an indicator system for assessing the UFR of Yingtan and proposes practical improvement directions for UFR.
]]>Water doi: 10.3390/w16060833
Authors: Young-Hyo Kim In-Hwan Cho Ha-Kyung Kim Eun-A Hwang Byung-Hun Han Baik-Ho Kim
This study investigates the ecological effects of weirs on water quality and phytoplankton communities in the South Han River (SHR) over a two-year period. By focusing on three key weirs—Kangcheon Weir, Yeoju Weir, and Ipo Weir—the research examines how artificial structures influence river hydrodynamics, nutrient cycles, and algal growth patterns. Utilizing water quality measurements, phytoplankton analysis, and environmental factor assessments, the study identifies significant fluctuations in water quality parameters and phytoplankton abundance across the surveyed points. The analysis reveals a direct correlation between environmental conditions such as temperature, flow rates, and nutrient concentrations, particularly nitrogen and phosphorus, and the proliferation of harmful cyanobacteria, notably Microcystis. This research highlights the critical role of comprehensive management strategies that consider hydraulic residence time, nutrient balance, and temperature regulation to mitigate the impacts of weirs on river ecosystems and improve water quality in the SHR.
]]>Water doi: 10.3390/w16060832
Authors: Diego Escobar-González Marcos Villacís Sebastián Páez-Bimos Gabriel Jácome Juan González-Vergara Claudia Encalada Veerle Vanacker
Soil moisture is a critical variable in the hydrological cycle and the climate system, significantly impacting water resources, ecosystem functioning, and the occurrence of extreme events. However, soil moisture data are often scarce, and soil water dynamics are not fully understood in mountainous regions such as the tropical Andes of Ecuador. This study aims to model and predict soil moisture dynamics using in situ-collected hydrometeorological data for training and data-driven machine-learning techniques. Our results highlight the fundamental role of vegetation in controlling soil moisture dynamics and significant differences in soil water balance related to vegetation types and topography. A baseline model was developed to predict soil moisture dynamics using neural network techniques. Subsequently, by employing transfer-learning techniques, this model was effectively applied to different soil horizons and profiles, demonstrating its generalization capacity and adaptability. The use of neural network schemes and knowledge transfer techniques allowed us to develop predictive models for soil moisture trained on in situ-collected hydrometeorological data. The transfer-learning technique, which leveraged the knowledge from a pre-trained model to a model with a similar domain, yielded results with errors on the order of 1×10−6<ϵ<1×10−3. For the training data, the forecast of the base network demonstrated excellent results, with the lowest magnitude error metric RMSE equal to 4.77×10−6, and NSE and KGE both equal to 0.97. These models show promising potential to accurately predict short-term soil moisture dynamics with potential applications for natural hazard monitoring in mountainous regions.
]]>Water doi: 10.3390/w16060831
Authors: Chunjing Liu Zhen Liu Jia Yuan Dong Wang Xin Liu
Predicting short-term urban water demand is essential for water resource management and directly impacts urban water resource planning and supply–demand balance. As numerous factors impact the prediction of short-term urban water demand and present complex nonlinear dynamic characteristics, the current water demand prediction methods mainly focus on the time dimension characteristics of the variables, while ignoring the potential influence of spatial characteristics on the temporal characteristics of the variables. This leads to low prediction accuracy. To address this problem, a short-term urban water demand prediction model which integrates both spatial and temporal characteristics is proposed in this paper. Firstly, anomaly detection and correction are conducted using the Prophet model. Secondly, the maximum information coefficient (MIC) is used to construct an adjacency matrix among variables, which is combined with a graph convolutional neural network (GCN) to extract spatial characteristics among variables, while a multi-head attention mechanism is applied to enhance key features related to water use data, reducing the influence of unnecessary factors. Finally, the prediction of short-term urban water demand is made through a three-layer long short-term memory (LSTM) network. Compared with existing prediction models, the hybrid model proposed in this study reduces the average absolute percentage error by 1.868–2.718%, showing better prediction accuracy and prediction effectiveness. This study can assist cities in rationally allocating water resources and lay a foundation for future research.
]]>Water doi: 10.3390/w16060830
Authors: Maria Concetta Bruzzoniti Massimo Del Bubba Edgardo Giordani Donatella Fibbi Mihail Simion Beldean-Galea Dariusz Piesik Luca Rivoira
Treated water reuse is vital for sustainable water management and reducing the strain on freshwater resources, particularly in agriculture, which has a great impact on freshwater withdrawal. Despite the benefits, the reuse of treated wastewater carries risks due to residual chemical and microbiological contaminants, such as the organic micropollutants polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), which are not fully removed by current treatment processes and can affect plant growth and human health when used for irrigation. This study focuses on monitoring the PAHs and PCBs in wastewater used for irrigating strawberries, assessing their transfer to crops and potential health risks. The effluents of four wastewater treatment plants were monitored for two years (2017 and 2018) and used to irrigate strawberries grown in plot installations. Effective and robust analytical methodologies (60–99% recoveries, optimal reproducibility) were developed for wastewater and strawberry analysis. The analysis of the treated wastewaters showed the presence of residual PAH and PCB concentrations at hundreds of ng/L. The strawberry crops were further analyzed to measure the PAHs and PCBs. Since two PAHs were present in strawberries, a risk assessment was performed (EPA methodology), finding that the residual contamination of treated waters does not pose a significant health risk, for both adults and children, through the consumption of fruits.
]]>Water doi: 10.3390/w16060829
Authors: Yunlong Ke Xianfang Song Lihu Yang Shengtian Yang
Frequent surface water–groundwater interactions and prevalent anthropogenic inputs make karst water systems vulnerable to human disturbance. As a typical karst region in North China, the Jinan Spring Catchment has become increasingly threatened due to rapid population growth and urban expansion. In this study, the local river–spring interaction and its interference with the hydrogeochemical evolution of groundwater are evaluated based on water stable isotopes and hydrochemistry. Twenty-two karst groundwater, eleven Quaternary pore water, sixteen spring water, and thirty-two surface water samples were collected during low- and high-flow conditions over the course of a year. The isotopic signatures of four different water types display significant differences, reflecting the recharge–discharge relationship of the karst water system. Mountainous springs feature lighter isotopes, whereas urban springs have significantly heavier isotopes. The result of end-member mixing analysis shows that the surface–groundwater interaction varies spatially and temporally within the spring catchment. Urban springs receive considerable replenishment from the surface water, especially after rainy episodes (up to 50%), while mountainous springs show little hydraulic dependence on surface water leakage (4~6%). Local mineral dissolution (including calcite, dolomite, gypsum, and halite), CO2 dissolution/exsolution, and cation exchange are the main hydrogeochemical processes constraining water chemistry in the spring catchment. The deterioration of water quality can be attributed to anthropogenic influences involving the discharge of domestic effluents, agricultural activities, and irrigation return flow. The findings of this work can improve our understanding of the complex karst water system and serve as a reference for sustainable groundwater management in other karst areas of northern China.
]]>Water doi: 10.3390/w16060828
Authors: Kyung-Su Choo Jung-Ryel Choi Byung-Hyun Lee Byung-Sik Kim
With the increase in both rainfall and intensity due to climate change, the risk of debris flows is also increasing. In Korea, the increasing damage caused by debris flows has become a social issue, and research on debris-flow response is becoming increasingly important. Understanding the rainfall that induces debris flows is crucial for debris-flow response, and methods such as the I-D method have been used to evaluate and predict the risk of debris flows. However, previous studies on debris flow-induced rainfall analysis have been limited by the subjective decision of the researcher to select the impact meteorological stations, which greatly affects reliability. In this paper, in order to establish an objective standard, various maximum allowable distances between debris-flow disaster areas and meteorological stations were adjusted to 1, 3, 5, 7, 9, 11, 13, and 15 km using the CTRL-T automatic calculation algorithm, and the optimal maximum allowable distance suitable for Korean terrain was derived through parameter sensitivity analysis. Based on this, we developed a nomogram for sediment disaster risk prediction and warning in Gangwon-do, and applied it to past disaster cases, and found that, although the prediction time for each stage varies depending on the maximum allowable distance, on average, it is possible to predict the risk of sediment flows 4 to 5 h in advance. It is believed that the results of this study can be used to reduce sediment flow damage in advance.
]]>Water doi: 10.3390/w16060827
Authors: Mingyu Ji Debin Jia Qingfeng Miao Yusheng Hao Shuling Chen Ting Liu Lina Yang Xiaoyan Li Weiying Feng
The improvement of water usage efficiency and productivity, as well as the development of effective water management plans, necessitates a comprehensive understanding of how water utilization patterns in different soil layers within arid and semi-arid climates impact the capacity of plant roots to absorb water. However, there is currently no knowledge regarding the water use strategies employed by artificial yellow willow. So, we conducted a study on the hydrogen and oxygen isotopic composition of rainfall in yellow willow (Salix gordejevii) from the semi-arid region located at the southern edge of the Hunshandak Sandland in China. This study utilized measured data on xylem water, groundwater, soil moisture, and rainfall. By employing a combination of the direct comparison method and the MixSIAR model, we investigated the water uptake strategies employed by yellow willow throughout its growing season. The findings revealed that the mean δ D was highest in precipitation and lowest in groundwater, whereas the mean δ18O was highest in stem water and lowest in groundwater. The δ D and δ18O fluctuated significantly in precipitation but were steady in groundwater. Because precipitation was significantly less than evaporation, the slope and intercept were lower for the local than global atmospheric precipitation line. Water availability steadily declined with increasing depth. Lower δ18O values were caused by precipitation diluting the soil water. The MixSIAR results indicated that the primary source in May, September, and October was utilized at 19%, 18%, and 18%, respectively. In contrast, the utilization rate of each source varied considerably in June, July, and August (the primary source was utilized at 19%, 18%, and 18%, respectively). Comparatively high rates of water absorption and utilization were observed in June (19% of the total water source), July (18%), and August (23%). Therefore, the vertical distribution of the root system and variations in the soil water content regulate water usage for the yellow willow. To prevent excessive water usage and promote ecosystem restoration with artificial yellow willow plantations in water-limited desert settings, policy makers should consider the patterns of plant water use and soil water availability. By selecting drought-adapted plant species and optimizing irrigation management, it is possible to reduce water wastage and ensure that water is used efficiently for revegetation and ecosystem restoration, avoiding overuse of water and maintaining the sustainability of revegetation in water-stressed desert areas.
]]>Water doi: 10.3390/w16060826
Authors: Xiaodong Xu Peining Zhu Yaya Song Weijie Chen Lin Chen Jia Weng Teng Xu Yuke Wang
In recent years, the detection of offshore pile foundations has received wide attention in engineering. Compared with traditional methods, the O-cell test has unique advantages in offshore pile foundation detection. To study the load transfer characteristics of the O-cell method for pile testing in coastal soft soil foundation, this paper established the pile–soil numerical model to simulate the O-cell and traditional testing processes. The finite element method and equal displacement method are combined to calculate the conversion coefficient and ultimate bearing capacity, and the distribution forms of axial force, side friction resistance, and tip resistance are discussed. The research results show that the O-cell test method and the traditional method have different load transfer forms. By introducing the equal displacement method into the O-cell pile–soil model, the error between the equivalent conversion ultimate bearing capacity and the calculation result of the surcharge method is less than 0.5%, and the O-cell conversion coefficient can be accurately calculated.
]]>Water doi: 10.3390/w16060824
Authors: Li Gu Yingying Sun Cheng Gao Liangliang She
In the context of accelerating urbanisation, the issue of urban stormwater flooding security has garnered increasing attention. Further development of urban stormwater management techniques is imperative to achieve more stable, precise, and expeditious simulation outcomes. The calibration of model parameters, which is a pivotal phase in stormwater simulation endeavours, is hampered by challenges such as substantial subjectivity, time intensiveness, and low efficiency. Therefore, this study introduces a parameter calibration model coupled with the Non-dominated Sorting Genetic Algorithm III (NSGA-III). This model utilises the Nash–Sutcliffe efficiency (NSE) and peak relative error (PE) values for various rainfall events as objective functions to calibrate and assess the study target. The two rainfalls used for rate determination had NSE values greater than 0.9 and absolute PE values less than 0.17; the rainfall used for validation had NSE values greater than 0.9 and absolute PE values less than 0.27. Thus, the results of the model for the rate determination of the parameters are reliable. In addition, the inverted generation distance and hypervolume values indicate that the iterative process of the algorithm during population evolution demonstrated stable iterative outcomes and ensured sound population quality. Both reach relative stability after 40 iterations. In conclusion, the proposed multi-objective parameter calibration model integrated with NSGA-III offers dependable calibration results and robust computational efficacy, presenting novel avenues and perspectives for urban stormwater model parameter calibration and simulation.
]]>Water doi: 10.3390/w16060825
Authors: Yong Hu Tianling Qin Guoqiang Dong Xiaofeng Chen Hongwei Ruan Qibing Zhang Lei Wang Minjie Wang
The Linhuaigang flood control project (LFCP), situated on the Huaihe River, China, uses the river channels upstream of the LFCP, together with the hinterland areas outside the channels, to retain and store fluvial floodwaters that exceed the downstream channel’s discharge capacity. The hinterland areas are split into seven flood storage areas, three floodplain areas, eight polder areas, and three flood-control-protected areas, and they are connected to the river in various ways. A coupled hydrodynamic model was established to simulate the hydrodynamic and water volume exchange between the river channels and the hinterland areas. The flood storage area, under the control of a flood diversion sluice, was simulated with a 2D hydrodynamic model, and the inflow process initiated by the flood diversion sluice was simulated as a control structure. The polder area was generalized as a reservoir that would be filled in several hours once put into use because of its small size. The uncontrolled inflow process between the flood-control-protected areas and the channel was simulated by means of a dam break model, which could simulate levee breaching. The flooding within the flood-control-protected area, which represents a vast space, was simulated with a 2D hydrodynamic model. The floodplain area was laterally connected to the river channel along the river levee. The difference between the simulated and the measured flood peak water stage did not exceed 0.2 m in 2003 and 2007, indicating that the accuracy of the model was relatively high. In the scenario of a design flood with a return period of 100 years, the flood storage areas and the LFCP were used in the following order: Mengwa, Qiujiahu, Nanrunduan, Shouxihu, Jiangtanghu, Chengxihu, Chengdonghu, and the LFCP. When the Huaihe River encounters a flood with a return period of 1000 years that exceeds the design standard, the highest water stage upstream of the LFCP and Zhengyangguan shall not exceed 29.30 m and 27.96 m after the use of all the flood storage areas, floodplain areas, and flood-control-protected areas. The results of this research can provide technical support for the flood risk management of the LFCP.
]]>Water doi: 10.3390/w16060823
Authors: Tianzhuang Ye Xinchao Hu Kaiyuan Wang Yunfei Qu Jiancong Lu Renjiang Yuan Lei Jiao
The rotary energy recovery device (RERD) plays an important role in reverse osmosis (RO) desalination; however, few investigations on the formation and influence of lateral force on the RERD rotor have been published. The transient characteristics of lateral force and its relationship with pressure distribution and fluctuation in the clearance were analyzed via computational fluid dynamics (CFD) simulation. The clearance pressure distribution and lateral force were quantified under different working conditions. The eccentricity of the rotor, resistance torque and decrease in the rotary speed due to the lateral force were simulated and they were found to change with flow rate and pressure of high-pressure outlet (PHO). A new rotary speed prediction method including the effect of PHO was developed. With the increasing flow rate or PHO, the stability of RERD declined. A design optimization direction was proposed. The variation trends of rotary speed, pressure in the clearance and its fluctuation were verified through experiment. This research provides an explanation why in practice the rotary speed decreases with increasing pressure. The conclusions obtained herein can be of great significance for future research on improving the stability and lifespan and reducing the maintenance consumption of RERD.
]]>Water doi: 10.3390/w16060822
Authors: Norio Harada Yoshifumi Satofuka Takahisa Mizuyama
New Japanese regulations governing earth embankment construction were introduced after a debris flow in Atami City, Shizuoka Prefecture, caused significant damage. Slope failures block river channels during earthquakes, triggering flooding, inundation, and debris flows. Appropriate risk assessments are crucial for residential areas potentially impacted by earthen embankment landslides during seismic events. This study evaluates the methods used to assess the potential damage caused by such landslides and previous research on the harm caused by embankment failures during earthquakes. We derived predictive equations based on statistical analyses of historical dam landslides that triggered river channel blockages when residential earth embankments failed in the Nigawa Yurino area. The equations describe the morphologies of landslide dams in river channels. The results indicated that the predictive equations were reasonably accurate. We built and validated a two-dimensional model of landslide dam overtopping and breaching using experimental data on a gently sloping dam. We derived the outflow volumes associated with residential earth embankment failures when full reservoirs breached in the Nigawa Yurino area. Our findings suggest that the peak outflow volumes after such embankments breach are generally lower than those associated with dam landslides or deep-seated dam failures, but higher than those of glacial lake outburst floods.
]]>Water doi: 10.3390/w16060821
Authors: Pingping Zhao Ruiming Zhang Mengdi Hu
Due to its high acidity and toxic metal content, acid mine drainage (AMD) needs to be properly treated before being discharged into the environment. This study took the AMD collected from one specific mine in China as a sample and investigated the treatment methodology for AMD. The water quality of the AMD was measured, and the sample was treated with caustic soda (NaOH) and shell powder (one kind of conventional neutralizer, mainly composed of CaCO3) by the neutralization method. The results show that the AMD has a relatively low pH (2.16) and contains high concentrations of Fe (77.54 g/L), Mn (621.29 mg/L), Cu (6.54 mg/L), Ca (12.39 mg/L), and Mg (55.04 mg/L). NaOH was an effective neutralizer to treat the AMD and performed much better than shell powder. Various metals were precipitated, in the order of Fe(III), Cu, Fe(II), Mn, Ca, and Mg. The metal removal mechanisms included precipitation, adsorption, and co-precipitation. The optimal reaction conditions were the reaction duration was selected as 5 min and the mass ratio of NaOH to AMD was 0.16:1 (w:v). By this stage, the pH rapidly increased from 2.16 to 8.53 during AMD-NaOH interactions and various metals were efficiently removed (from 86.71% to 99.99%) by NaOH. The residual mass concentrations of Fe, Mn, Cu, Ca, and Mg after the treatment were 1.52, 1.77, 0.10, 1.65, and 2.17 mg/L, respectively. These data revealed that NaOH was a good treatment regent for this kind of AMD, based on the discharge criteria of China (GB28661 2012). Also, the shell powder was a helpful neutralizer for pH adjustment and copper removal. This neutralization method has the advantages of convenient operation, high speed, good effect, simple equipment, and low infrastructure cost. In addition, the resulting neutralized residue is a valuable and high-quality raw material, which can be used in metal smelting and separation.
]]>Water doi: 10.3390/w16060820
Authors: Sutapa Debi Mohammad Abdus Salam Simon Kumar Das Md. Shahanoor Alam Mohammad Lutfar Rahman Md. Shakhawate Hossain Sabuj Kanti Mazumder
A 60-day experimental trial was conducted to evaluate the effect of different stocking densities, probiotic supplementation, and a biofloc system on the growth and physiological responses of Puntius sophore in laboratory conditions. P. sophore (8.64 ± 1.24 g) was obtained from the Brahmaputra River, Mymensingh, and immediately transferred to a flow-through water system. In experiment 1, fish were subjected to three treatments (20 fish per 400 L as LD, 25 fish per 400 L as MD, and 30 fish per 400 L as HD), and similarly, in experiment 2, three different types of diets were provided (control diet (D1), biofloc (D2), and a probiotic-containing diet (D3)). Three replications were used in the completely randomized experimental design. Growth parameters, viz. TLG, BWG, FCR, FCE, SGR, RGR, and DGR, were significantly influenced by stocking density and probiotics (p < 0.05). The highest growth rate was observed in LD and in D3. The lowest FCR was also observed in LD and in D3, while highest was in HD (30 fish per 400 L) and in D2. Though stocking density does not impact the blood profile, with the exception of WBC, in the case of feeding regime, WBC, RBC, MCV, MCH, and PLT levels differed significantly (p < 0.05); however, all haematological measures were within the normal range in both experiments, and the fish’s physiological conditions were better in LD and feeding with probiotic supplementation (D3). The results obtained from this study suggested that the welfare of P. sophore is adversely affected by high stocking density and increased growth and physiological conditions when cultured with LD and supplemented with probiotics.
]]>Water doi: 10.3390/w16060819
Authors: Yongsuk Hong Jungwoo Shin Hyunhong Choi JongWuk Ahn
Parallel pipeline projects can contribute to ensuring a safe and stable water supply and preventing or mitigating losses caused by water pipeline accidents. However, because these projects require a significant investment, feasibility tests are essential prior to their implementation. Considering the public nature of the water supply, the direct beneficiaries of the project and people from other regions can place value on such projects. Thus, this study estimates the value of parallel pipeline projects using the contingent valuation method (CVM) and the swing weighting technique. We constructed two contingent valuation surveys: one asking about the willingness to pay (WTP) for a parallel pipeline project within the respondent’s region and the other asking about the WTP for a project outside the region. The results show that the annual WTP per household for projects within and outside the region was 113,669 KRW (87.98 USD) and 5493 KRW (4.25 USD), respectively. These results indicate that the value perceived by people from outside the region should be considered. Additionally, the results from the swing weighting technique and WTP analysis show that the values that respondents generally consider important and those that can leverage the overall project value are distinct. This study’s results provide insights into the implementation of parallel pipeline projects in South Korea. Furthermore, this study’s analytical framework can be used for the valuation of other public infrastructure projects.
]]>Water doi: 10.3390/w16060818
Authors: Yizhen Wang Xin Liu Riu Liu Zhijie Zhang
With the development of mathematical statistics, people have developed the spatiotemporal interpolation methods based on the spatial interpolation method or the temporal interpolation method. These methods fully consider the comprehensive effects of time series changes and spatial distribution to better handle complicated and changeable meteorological element data. This article systematically reviews the current research progress of spatiotemporal interpolation methods for spatiotemporal sampling data of meteorological origin. Spatiotemporal interpolation methods of meteorological elements are classified into three categories: spatiotemporal geostatistical interpolation methods, spatiotemporal deterministic interpolation methods, and spatiotemporal mixed interpolation methods. This article summarizes the theoretical concept and practical application of the spatiotemporal interpolation methods of meteorological elements, analyzes the advantages and disadvantages of using spatiotemporal interpolation methods for estimating or forecasting meteorological elements, combined through some measures and their application to explain the accuracy of the spatiotemporal interpolation methods; and discusses the problems and challenges of spatiotemporal interpolation. Finally, the future research focus of spatiotemporal interpolation methods is proposed. This article provides a valuable method reference for estimating or predicting meteorological elements such as precipitation in unsampled points.
]]>Water doi: 10.3390/w16060816
Authors: Anujit Phumiphan Suwapat Kosasaeng Ounla Sivanpheng Rattana Hormwichian Anongrit Kangrang
In reservoir operation rule curves, it is necessary to apply rule curves to guide long-term reservoir management. This study proposes an approach to optimizing reservoir operation rule curves (RORCs) using intelligent optimization techniques from the firefly algorithm (FA) and a unique combination method utilizing the artificial bee colony and cultural algorithm (ABC-CA). The aim is to establish a connection with the simulation model to determine the optimal RORCs for flood control. The proposed model was used to determine the optimal flood control RORC for the Nam-Oon Reservoir (NOR) in northeastern Thailand. A minimum frequency and minimum average of excess water were provided as an objective function for assessing the efficiency of the search process. The evaluation of the effectiveness of flood control RORCs involved expressing water scarcity and excess water situations in terms of frequency, magnitude, and duration using historical inflow data synthesized from 1000 events. The results demonstrated that when using the obtained RORC to simulate the NOR system for reducing flooding in long-term operations, excess water scenarios were smaller than those using the current RORC. The results showed that the excess water scenario using the RORC obtained from the proposed model can reduce the excess water better than the current RORC usage scenario. In decreasing flood situations, the newly acquired RORC from the suggested FA and ABC-CA models performed better than the current RORC.
]]>Water doi: 10.3390/w16060817
Authors: Patrícia Palma Alexandra Tomaz
Water is the main limiting factor in agricultural production in regions where the annual or seasonal rainfall is insufficient for the water requirements of crops [...]
]]>Water doi: 10.3390/w16060815
Authors: Tao Song Yuntong Zhao Min Wang Zhe Cheng
The river and lake chief system offers a valuable policy toolkit to mitigate the degradation of water ecology, thereby bolstering water resource management for sustainable water development in China. To evaluate the effects of implementation and improve policy, this study took Beijing as a typical case and conducted a quantitative assessment using multidimensional data. The findings suggest that while the river and lake chief system in Beijing is effective and has significantly contributed to the ecological management of rivers and lakes, there are also notable regional disparities and urban–rural divergences. In addition, human activities are the main sources of environmental pollution in rivers and lakes, which should be the focus of the river and lake chief system. The river and lake chief system needs to embed more public participation and cooperative governance. This research aids in better understanding China’s river and lake chief system for both researchers and practitioners, facilitating the advancement of the knowledge body of global water policy and governance.
]]>Water doi: 10.3390/w16060814
Authors: Víctor Fabregat Juana María Pagán
The focus on emerging contaminants (ECs) in wastewater has intensified due to the considerable risks they present to human health and wildlife. This paper presents the results of the technical–economic assessment of the Clean Up solution, carried out in the framework of the project entitled “Validation of Adsorbent Materials and Advanced Oxidation Techniques to Remove Emerging Pollutants in Treated Wastewater”. The viability of the Clean Up system is evaluated by being applied as an advanced treatment system for treated urban wastewater, that is, for the elimination of pathogens and emerging pollutants (EPs), while considering the established quality criteria by current regulations. In this sense, it is a technology that has been successfully validated at an experimental level, and that offers similar removal performance compared to that of the most efficient alternatives available on the market. The technical–economic assessment has been conducted through a systematic process. Initially, the estimation involved the calculation of treatment costs for the Clean Up system when applied at an industrial scale. Subsequently, the treatment costs were estimated for the most favorable technological alternative to the Clean Up system from a technical–economic standpoint, also applied at an industrial scale, within identical scenarios and conditions as those assumed for the Clean Up system. The final step involved a comprehensive comparison of treatment costs between both alternatives, implemented uniformly under analogous conditions and assumed similar performance across all cases.
]]>Water doi: 10.3390/w16060813
Authors: Weitao Liu Yuying Ren Xiangxi Meng Bo Tian Xianghai Lv
The water yield of aquifers increases the risk of water inflow, threatens the safe production of coal mines, and even causes geological disasters and construction hazards. To predict water yield quickly and accurately, multiple composite factors are used to invert unit water inflow rates to judge water yield grade. Taking the typical representative of north China-type coal fields as an example, six factors are selected: aquifer thickness, the radius of influence, normalized drawdown, permeability coefficient, the core rate of drilling holes, and the proportion of clay thickness to the thickness of the lower group. The whale optimization algorithm (WOA)–convolutional neural network (CNN)–support vector machine (SVM) model is established with the unit water inflow rate as the forecast target, and different models are selected for comparison. The water yield zoning map is obtained by bringing the borehole data into the model for prediction. The findings indicate that the root mean square error and average absolute error of the composite predictive model models are 0.0318 and 0.0268, respectively, and the model outperforms alternative models. The predicted water yield zoning aligns well with the actual conditions, offering a novel paradigm for water yield assessment.
]]>Water doi: 10.3390/w16060812
Authors: Yang Zheng Long Meng Guang Zhang Peng Xue Xin Wang Chiye Zhang Yajuan Tian
The benefits of variable speed centrifugal pumps include high stability, a broad operating range, and adjustable input power. In water distribution systems, the pump units are increasingly using variable speed technology. The energy-saving features and operational stability of the pump station are directly impacted by the hydraulic performance and the operation strategy. In this study, CFD numerical analysis and model tests were adopted to design and evaluate the hydraulic performance of the variable speed centrifugal pump with large flow and wide head variation in Liyuzhou Pump Station. Under the premise of ensuring the wide head variation, the optimized centrifugal pump met the requirements of hump margin and efficiency in the high head zone and the cavitation margin in the low head zone. The test results demonstrated that the operational range of the variable speed centrifugal pump was successfully widened by reasonable hydraulic parameters selection and impeller optimization. The safe and efficient operational range of the variable speed unit was determined by means of taking the performance requirements of the pump’s maximum input shaft power, cavitation characteristics and pressure fluctuation into consideration. The scientific and reasonable operational path to meet the various operation needs was also investigated and determined for the pump station’s actual operation needs. A high efficiency, safe operation, and a simplified control logic were achieved by using the operational path, which makes it a reasonable potential guide for hydraulic design and operational optimization of variable speed centrifugal pumps with large flow and wide head range.
]]>Water doi: 10.3390/w16060811
Authors: Jonas Neumann Christian Scheid Ulrich Dittmer
Urban drainage systems are generally designed to handle rainfall events only up to a certain intensity or volume. With climate change, extreme events that exceed the design storms and consequently result in flooding are occurring more frequently. Nature-based solutions (NBSs) have the potential to reduce the pressure on urban drainage systems and to increase their resilience. This study presents an approach to compare and evaluate the effectiveness of NBSs for flood mitigation using a coupled 1D/2D model of surface and sewer flow. The study analyzes the effect of infiltration systems (dimensioned to return periods of T = 5 and 100 years), various green roofs, and tree pits considering the different degrees of implementation. The NBSs are represented as LID elements according to SWMM. As expected, the mitigation effect of NBSs declines with increasing rainfall intensities. However, infiltration systems dimensioned to T = 100 years achieve almost three times the flood reduction compared to systems dimensioned to T = 5 years, even during extremely heavy rainfall events (100 mm), resulting in a reduced total flood volume of 15.1% to 25.8%. Overall, green roofs (excluding extensive green roofs) provide the most significant flood reduction (33.5%), while tree locations have the least effect.
]]>Water doi: 10.3390/w16060810
Authors: Jingjing Xu Ying Zhao Yin Chen Pengfei Du Liqin Qu
The Inner Mongolia section of the Yellow River is a primary alluvial segment of the main channel. The variations in water and sediment not only alter the cross-sectional morphology and flow capacity of the river but also impact the scheduling of upstream cascade reservoirs. Based on runoff and sediment load data and topographic information from typical hydrological stations, the characteristics of runoff and sediment load variations and the evolutionary pattern of siltation in the Inner Mongolia River section were analyzed via trend analysis methods, Mann–Kendall test methods, the sediment load transport rate method, and the water level–flow relationship. The results showed that the water and sediment loads at the hydrological stations in the Inner Mongolia River section significantly changed from the 1960s to after 2000, with runoff decreasing by approximately 22% to 32% and the sediment load decreasing by approximately 65% to 73%. Sedimentation in the river section generally increased, and the average annual siltation amount reached 0.144 billion t. The joint utilization of the Longyangxia and Liujiaxia reservoirs in 1987 was the main reason for the rapid increase in siltation, and siltation in the Inner Mongolia River section was slightly reduced after 2005. In addition, the critical sediment load coefficients of the Bayangaole–Sanhuhekou and Sanhuhekou–Toudaoguai River sections were 0.0073 and 0.0051 kg·s/m6, respectively, from 1952 to 1968, and 0.0053 and 0.0037 kg·s/m6, respectively, from 1969 to 2020. This study could provide technical support for river flood control and reservoir water sediment regulation in Inner Mongolia.
]]>Water doi: 10.3390/w16060808
Authors: Alina Bărbulescu Nayeemuddin Mohammed
This article aims to analyze the alteration in water discharge due to the building of one of the largest dams in Romania. Modifications in the hydrological patterns of the studied river were emphasized by a complex technique that includes decomposition models of the series into trends, seasonal indices, and random components, as well as into Intrinsic Mode Functions (IMFs). The Mann–Kendall trend test indicates the existence of different positive slopes for the subseries S1 and S2 (before and after the inception of the Siriu dam, respectively) built from the raw series, S. The stationarity hypothesis was rejected for all series. The multifractal analysis shows two different patterns of the data series. After decomposing the subseries S1 and S2, it resulted that the seasonality indices are not the same. Moreover, the seasonal variations decreased after building the dam. Empirical Mode Decomposition (EMD) unveils different short- and long-term patterns of the series before and after building the dam, concluding that there is a significant alteration in the river discharge after the dam’s inception.
]]>Water doi: 10.3390/w16060809
Authors: Junyan Gao Feng Chen Xiangtian Nie Xuewan Du
In China, the water network project plays a pivotal role in optimizing water resources allocation, enhancing regional water resources carrying capacity, and bolstering high-quality economic development. This study is grounded in the spatial interconnection of water resources, serving as the foundation for constructing a spatial measurement model. Leveraging data from 558 panel samples encompassing 31 provinces (including municipalities and districts) in China between 2003 and 2020, this research unveils the inherent correlation between the establishment of the water network and economic as well as social development. The findings indicate the following: (1) Considering inputs, outputs, and nonconsensual outputs, regional disparities in the SBM (slacks-based measure) value of the water network exist, demonstrating an overall increasing trend annually. In 2020, the nationwide average benefit level of input–output in water network construction reached 0.603. (2) Moran’s I test, predicated on the weight matrix of spatial water transfer information, reveals a spatial positive autocorrelation. All tests pass the significance threshold of 5%, affirming the presence of spatial agglomeration due to project construction, operation, and the interconnectedness of water resources. (3) SDM (spatial Durbin model) regression analysis elucidates that per capita GDP, resource endowment, technological innovation level, consumption index, and average wage significantly influence the growth of water network efficiency. Specifically, per capita GDP and the consumption index exert negative influences. Moreover, aspects such as regional resource endowment, technological innovation level, industrial and agricultural water demand, average wage, and other spatial dependencies exhibit a notable positive spatial spillover effect. (4) The SDM model suggests that per capita GDP growth fails to yield a significant spatial spillover effect on neighboring regions. Instead, it highlights a substantial indirect effect and spatial dependence of government attention among regions. These analyses are instrumental in optimizing the water resources allocation network system and enhancing investment efficacy.
]]>Water doi: 10.3390/w16060807
Authors: Jingui Wang Jinxia Sha Ruiting Liu Shuai Ren Xian Zhao Guanghui Liu
Soil moisture content is one of the most important soil indices for agriculture production. With the increasing food requirement and limited irrigation water sources, it is of great significance to accurately and quickly measure the soil moisture content for precision irrigation, especially in deficient agricultural areas, such as North China Plain. To achieve this goal, more attention was paid to the application of unmanned aerial vehicle multispectral reflectance technology. However, it was urgent to enhance the regression models between spectral data and soil realistic moisture content, and there were limited studies about the regression research on deep soil layers. Thus, the farmland of winter wheat–summer maize double cropping at Yongnian District, Hebei, North China, was selected as the study area. A six-band multispectral camera mounted on a low-altitude unmanned aerial vehicle (UAV) was used to obtain the field spectral reflectance with bands from 470~810 nm, and meanwhile, soil moisture content at different depths (10, 20, 30, 40, 50, and 60 cm) was measured after maize sowing. Unary linear regression (ULR), multivariate linear regression (MLR), ridge regression (RR), and an artificial neural network (ANN) were employed to establish regression models. The results demonstrated that the sensitive bands of spectral reflectance were 690 nm, 470 nm, and 810 nm. Those models all established significant regression at the depths of 0–20 cm and 40–60 cm, particularly at 10, 50, and 60 cm soil layers. However, for a depth of 20–40 cm, the prediction accuracy was generally lower. Among MLR, RR, and BP models, the MLR exhibited the highest identification accuracy, which was most recommended for the application. The findings of this study provide technical guidance and effective regression for the multispectral reflectance on the farmland of North China Plain, especially for deep soil layer moisture prediction.
]]>Water doi: 10.3390/w16060806
Authors: Yanjun Wang Yue Yuan Hao Xue Yin Yu Yang Shi Huina Wen Min Xu
The Yellow River basin serves as an important economic belt and industrial base in China, featuring numerous industrial parks. However, alongside its economic significance, the basin struggles with significant water environmental challenges. This study analyzed the operational status, influent water quality, and energy consumption of 63 centralized wastewater treatment plants (WWTPs) from 54 major industrial parks in the Yellow River basin. The scale of these WWTPs was primarily within the range of 1 × 104~5 × 104 m3/d, with an average hydraulic loading rate of 53.8%. Aerobic treatment processes are predominant. The influent concentrations of chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) in the WWTPs exhibited a right-skewed distribution. The BOD/COD ratio of the WWTPs fluctuated between 0.1 and 1.6, and 75% of the WWTPs showed a COD/TN ratio lower than eight. The average BOD5/TN was 2.7, and the probability of influent BOD5/TP > 20 was 84.6%. A significant linear correlation exists between the influent BOD and COD concentrations, while moderate linear relationships are also observed among NH3-N, TN and TP, emphasizing the importance of maintaining appropriate nitrogen and phosphorus levels for efficient pollutant removal. The average electricity consumption of WWTPs in the Yellow River basin in 2023 was 1.1 kWh/m3. It is important to upgrade these WWTPs and reduce their energy consumption. Further strengthening the construction of industrial wastewater collection and treatment facilities based on regional characteristics is recommended to promote the high-quality development of industrial wastewater treatment in the Yellow River basin.
]]>Water doi: 10.3390/w16060805
Authors: Marziyeh Haji Mohammadi Vahid Shafaie Aliakbar Nazari Samani Arash Zare Garizi Majid Movahedi Rad
Climate is one of the main drivers of hydrological processes, and climate change has caused worldwide effects such as water scarcity, frequent floods and intense droughts. The purpose of this study was to analyze the effects of climate change on the water balance components, high flow and low flow stream conditions in a semi-arid basin in Iran. For this reason, the climate outputs of the CanESM5 model under Shared Socioeconomic Pathways (SSP) scenarios SSP126, SSP245, and SSP585 were spatially downscaled by the Statistical Downscaling Model (SDSM). The hydrological process was simulated by the Soil and Water Assessment Tool (SWAT) model. Key findings include a 74% increase in evapotranspiration, a reduction by up to 9.6% in surface runoff, and variations in discharge by up to 53.6%. The temporal analysis of snow melting changes revealed an increase in the volume of snow melting during winter months and a reduction in the volume during spring. The projected climate change is expected to cause notable variations in high and low flow events, particularly under the SSP585 scenario, which anticipates significant peaks in flow rates. This comprehensive analysis underscores the pressing need for adaptive strategies in water resource management to mitigate the anticipated impacts of climate variability.
]]>Water doi: 10.3390/w16060804
Authors: Kun Wei Yuanmei Jiao Guilin Zhang Ying Wang Hua Zhang
The stability of irrigation water is critical for the sustainability of alpine agriculture. Based on monthly precipitation and terraced field water and spring water samples obtained between 2015 and 2016, the study used the mean residence time and isotope mixing model to analyze the influence of spring water residence time on irrigation water stability in the Hani Rice Terraces. The results indicate that: (1) The mean residence time of precipitation and terraced field water in spring water was 2.46 years and 1.55 years, respectively, implying that the terraced field’s irrigation water source could be refilled by spring water recharged 1.5–2.5 years ago. (2) The mean residence time of precipitation in ascending and descending springs was 2.73 years and 1.95 years, respectively. The mean residence time of terraced field water in ascending and descending springs was 1.54 years and 1.04 years, respectively. The ascending spring’s recharge water residence time is 0.5–0.8 years longer than that of the descending spring, indicating that the spring water exhibits intra-seasonal and inter-seasonal staggered peak recharging. At the same time, the total recharge period of the ascending–descending spring is extended to 1–3 years, which means the terraced fields have a drought resistance of three years. (3) The mean residence time of precipitation and terraced field water at higher altitudes in the ascending spring is 2.52 times and 3.73 times, respectively, while in the descending spring, it is 3.36 times and 6.49 times to the lower altitude region. This means that the mean residence time of the recharge water source in the lower terraced fields was shorter, and the elevation difference between ascending and descending springs was smaller, thereby regulating the spatial homogeneous distribution of recharge water sources in the terraced fields.
]]>Water doi: 10.3390/w16060803
Authors: Abdelkhaleq F. Taybi Youness Mabrouki Peter Glöer Christophe Piscart
Invasive species are a major threat to global biodiversity. Therefore, it is crucial to monitor their presence and expansion within invaded areas and carry out studies to improve our knowledge of their biology and ecology. One of the most effective and spectacular invaders among freshwater snails is the acute bladder snail (Physella acuta) (Draparnaud, 1805). This study aims to update the available data on P. acuta in Morocco and determine the main environmental factors that favor its distribution and expansion in this country. Field surveys were conducted in northern Morocco between 2014 and 2023, with a focus on protected areas such as Ramsar sites, and especially great geographical barriers such as the Middle Atlas Mountains and the Sebou and Moulouya River basins. The gastropods were collected using Surber samplers (20 × 25 cm surface area, 400 µm mesh), together with measurements of the physicochemical parameters of the water and other abiotic factors. The bladder snail is probably the most widespread freshwater snail in Morocco, where the species appears to be highly adaptable and can thrive in different habitats, including degraded ones, showing great plasticity in terms of the physicochemical parameters of the water. The main factor limiting the geographical distribution and abundance of P. acuta in the study area was water velocity and conductivity. However, further studies are required to address the future range of expansion of P. acuta in relation to climate change. Although one of the consequences of climate change is reduced water flow speed, which may promote its range of expansion in Morocco, salinization of streams may also reduce its ability to colonize new environments.
]]>Water doi: 10.3390/w16060802
Authors: Fulei Zhou Zhijun Li Yu Gao Haiqing Wang Jiantao Wei Bo Zhou
This study proposes a water resource pollution risk warning evaluation method. Firstly, an evaluation system is constructed, consisting of 15 secondary indicators in four aspects: water quality, ecology, utilization protection, and water disasters. Then, an improved AGA-AHP method and coefficient of variation method are used to determine the weights of each indicator. Cloud models are employed to describe the characteristics of standard clouds and evaluation clouds, establishing a two-dimensional cloud model with risk probability and hazard level as variables. Taking a certain region in Shandong Province, China, as an example, the quantitative analysis results indicate that the water pollution risk level in the area is classified as Level IV, with particular attention needed for water quality and management indicators. Simultaneously, a series of measures such as source control, monitoring and early warning, emergency response, and public participation are proposed to further reduce the risk. The research findings demonstrate the following: (1) The establishment of a comprehensive indicator system for multidimensional assessment; (2) The combination of the AGA-AHP method and cloud model for quantitative analysis; (3) The practicality of the method validated through the case study; (4) Providing a basis for subsequent decision-making. This study provides new insights for water environmental risk management, but a further optimization of the model to enhance predictive capability is required when applied in practical scenarios. Nevertheless, the preliminary validation of this method’s application prospects in water resource risk monitoring has been achieved.
]]>Water doi: 10.3390/w16060801
Authors: Chunhui Ma Ying Tu Yonglin Zhou Jie Yang Lin Cheng
Rockfalls are major geological hazards threatening prestressed concrete cylinder pipes (PCCPs) in water diversion projects. To accurately assess the impact of large deformation movements of rockfalls on PCCPs, this study utilized the continuous–discontinuous method to investigate the dynamic response of a PCCP under a rockfall. The impact mode of rockfalls, the mechanical characteristics of PCCP, and the nonlinear-contact characteristics between soil and PCCP were considered in this study. The advantages of continuous and discontinuous numerical simulation methods were utilized to establish a continuous and discontinuous coupling model of “tube-soil-rock” considering the interaction of soil and structure. The impact mechanism and process of PCCP under the rockfall were investigated by simulating the rockfall process and analyzing its spatiotemporal evolution. The influence of PCCP under rockfalls with different heights and radii was studied to clarify the effects of these two parameters on the PCCP. Combined with a practical application example of large-scale water transfer projects, there is a tendency of center flattening under static load and dynamic impact load, and the PCCP part directly below the impact point is the most dangerous. This investigation provided a comprehensive understanding of the impact mechanism of the PCCPs under rockfall. The findings of this study have significant implications for the design of the protection engineering of PCCPs and ensuring the safe operation of water diversion projects.
]]>Water doi: 10.3390/w16060800
Authors: Peiyao Zhang Shuang (Sophia) Chen Ying Dai Baraka Sekadende Ismael Aaron Kimirei
Nonpoint source pollution (NPS) has become the most important reason for the deterioration of water quality, while relevant studies are often limited to African river and lake basins with insufficient data. Taking the Simiyu catchment of the Lake Victoria basin as the study area, we set up a NPS model based on the soil and water assessment tool (SWAT). Furthermore, the rationality of this model is verified with the field-measured data. The results manifest that: (1) the temporal variation of NPS load is consistent with the variation pattern of rainfall, the average monthly output of total nitrogen (TN) and total phosphorus (TP) in the rainy season was 1360.6 t and 336.2 t, respectively, while in the dry season was much lower, only 13.5 t and 3.0 t, respectively; (2) in view of spatial distribution among 32 sub-basins, TN load ranged from 2.051 to 24.288 kg/ha with an average load of 12.940 kg/ha, and TP load ranged from 0.263 to 8.103 kg/ha with an average load of 3.321 kg/ha during the 16-month study period; (3) Among the land use types, the cropland contributed the highest proportion of TN and TP pollution with 50.28% and 76.29%, respectively, while the effect of forest on NPS was minimal with 0.05% and 0.02% for TN and TP, respectively. (4) Moreover, the event mean concentration (EMC) values of different land use types have been derived based on the SWAT model, which are key parameters for the application of the long-term hydrological impact assessment (L-THIA) model. Therefore, this study facilitates applying the L-THIA model to other similar data-deficient catchments in view of its relatively lower data requirement.
]]>Water doi: 10.3390/w16060799
Authors: Judy Marie Tayaban Dulawan Yoshiyuki Imamura Hideo Amaguchi Miho Ohara
Urban populations, especially vulnerable communities, are facing increasing flood risks due to the rising frequency of floods caused by climate change and rapid growth. Effective mitigation requires moving beyond physical and environmental approaches to embrace social dimensions. This study examined the prevailing social drivers of floods in flood-prone communities in Metro Manila, Philippines using social data acquired through a door-to-door household survey. Responses were assessed using exploratory and combined qualitative and quantitative analyses. The findings of this study show that the decision to remain in flood-prone areas is influenced by attachment to homes and acclimatization to the environment, convenience of accessible amenities to fulfill basic needs, livelihood dependence, economic considerations, house ownership, and perceived safety from floods. When choosing a place to live, the complex tradeoffs of residents are reflected, wherein daily economic concerns outweigh the possible flood damage. By understanding the social drivers of residency, policymakers and community leaders can develop targeted interventions and formulate strategies to address the root causes of the problem, leading to effective interventions and enhancing the resilience of urban communities.
]]>Water doi: 10.3390/w16060798
Authors: Mouldi Ben Meftah Danish Ali Bhutto Diana De Padova Michele Mossa
In this study, we attempt to experimentally investigate the flow turbulence structure in a partly vegetated channel. To achieve the objective of this study, we conducted extensive measurements of flow velocities within and outside the vegetated area, where the flow is fully developed. The experiments were conducted in a very large channel at the Coastal Engineering Laboratory of the Department of Civil, Environmental, Building Engineering and Chemistry at the Polytechnic University of Bari, Italy. The instantaneous three flow velocity components were accurately measured using a 3D-Acoustic Doppler Velocimeter (ADV)-Vectrino system at high frequency. Flow behaviors through the vegetated area, at the interface, and in the unobstructed area were analyzed via time-averaged velocities, turbulence intensity, correlation properties, spectral analysis, and vortex identification. Experimental results showed the development of three distinct characteristic flow zones: (i) a vegetated area of low streamwise velocity, high turbulence intensities, dominant inward interactions, and more intense power spectrum, (ii) a shear layer zone of increasing streamwise velocity, more enhanced transverse flow motion, exponential decrease in turbulence intensities, and frequent ejection and/or outward interaction events, and (iii) a free-stream zone of higher and almost constant streamwise velocity, lower turbulence intensities, frequent sweep and/or inward interaction events, and less intense streamwise power spectrum. The results brought further insights into the flow behaviors in these characteristic flow zones. The extensive and detailed measured data can provide a basis for improving and calibrating numerical simulations of partly vegetated channels.
]]>Water doi: 10.3390/w16060797
Authors: Ramon Sanchez-Rosario Jesus Garcia Vivian Rodriguez Kevin A. Schug Zacariah L. Hildenbrand Ricardo A. Bernal
Numerous treatment modalities have been employed over the years to eradicate bacterial communities in industrial wastewater. Oxidizing agents and chemical additives, such as ozone, permanganate, glutaraldehyde, and chlorine, are effective in treating microbial contaminants that are typically found in domestic wastewater. However, the chemical complexity of water produced from fracking requires novel approaches, because the microbes have developed mechanisms to overcome typical disinfectants. In this work, we test the effectiveness of bacteriophages for the eradication of two model bacteria from produced water: Pseudomonas aeruginosa and Bacillus megaterium. These bacteria were grown in low salinity produced water and exposed to their corresponding phage. Overall, the total inactivation of the P. aeruginosa population was achieved, as well as the inactivation of B. megaterium. These promising results provide a potentially useful tool for bacterial elimination in overall PW treatment, at an industrial scale. Particularly, since phage treatment is a rapid and cost-effective alternative. Moreover, these results fall within the objectives proposed as part of the sustainable development goals adopted worldwide.
]]>Water doi: 10.3390/w16060796
Authors: Elisa Pandelani Munzhelele Rabelani Mudzielwana Wasiu Babatunde Ayinde Wilson Mugera Gitari
The focus of this review article was to outline the sources, pathways, effects, occurrence, and spatial distribution of the most prescribed pharmaceuticals in wastewater and receiving waters of South Africa. Google Scholar, Web of Science, and Scopus were used to gather data from different regions. A zone-wise classification method was used to determine the spatial distribution and data deficiencies in different regions of South Africa. This review revealed that over 100 pharmaceutical compounds have been reported in South Africa’s various water sources and wastewater, with most studies and highest concentrations being documented in Gauteng and Kwa-Zulu Natal. The pharmaceutical concentration in water samples ranged from ng/L to µg/L. Aspirin, ketoprofen, diclofenac, ibuprofen, naproxen, erythromycin, tetracycline, sulfamethoxazole, acetaminophen, streptomycin, ciprofloxacin, ampicillin, carbamazepine, atenolol, pindolol, efavirenz, and zidovudine residues were among the frequently detected pharmaceutical residues in water bodies and wastewaters of South Africa. Based on the spatial distribution data, Gauteng has the highest number of pharmaceuticals (108) detected in waste and surface water, with the Northern Cape having no monitoring evidence. Therefore, to precisely ascertain the geographical distribution of pharmaceutical contaminants in South Africa, this review recommends that further research be carried out to track their occurrence in aquatic environments and WWTP, especially in isolated regions like Limpopo.
]]>Water doi: 10.3390/w16060795
Authors: Yousra El Mouine Amal El Hamdi Abderrahim Bousouis Youssouf El Jarjini Meryem Touzani Vincent Valles Laurent Barbiero Moad Morarech
The presence of fermentative hotspots in municipal waste dumps has been reported for several decades, but no study has focused on their size and shape. The uncontrolled landfill of Soub Sekt, covering an area of about 8 hectares in the Tadla plain in Morocco, is the source of a permanent pollution plume in the groundwater, detected by self-potential (SP) measurements. The study aims to detect and characterize these hotspots as well as the leachates that form within them. These hotspots are typically circular and smaller than 3 m in size, and they are concentrated within recent waste deposits. Intense electron transfer activities, particularly during redox reactions leading to metal solubilization, result in very low SP values (down to −60 mV), facilitating their detection. Several successive field campaigns suggest that they are active for 2–3 weeks. Due to the low permeability of the soils, highly mineralized leachates (average Electrical Conductivity 45 mS cm−1) rich in organic ions accumulate on the soil surface at the base of the waste windrows. There, they evolve by concentration due to evaporation and oxidation due to slow diffusion of atmospheric O2. Despite the small size of the hotspots generating the leachates, the accumulation of leachates in ponds and the low soil permeability limits the percolation rate, resulting in moderate but permanent groundwater pollution.
]]>Water doi: 10.3390/w16060794
Authors: Caixia Fu Fujun Li Hui Li Xuenong Yi
Reverse osmosis (RO) is a commonly used desalination technology, but due to high requirements concerning the quality of the feed water, there still exists permeate flux related to the operating conditions, and the solute removal rate is low. Electric fields have a facilitating effect on RO desalination performance. Previous studies have focused on investigating the combination of RO and electrodialysis (ED) processes separately, without directly exploiting their interactions. To address this issue, this study proposes a novel coupling device that combines both RO and ED technologies in a single unit and investigates their mutual enhancement effects on brackish water desalination. The results show that the coupled EDRO system can mutually enhance the performance of RO and ED processes. The permeate flux ratio of the RO membrane increased with increasing voltage, reaching a maximum value of 23.7% at a feed concentration of 10,000 mg/L. The solute rejection by the ion-exchange membrane also increased with increasing pressure, reaching a maximum value of 14.95% at the same feed concentration. In addition, the specific energy consumption of the coupled system was also reduced compared to a standalone operation, with maximum reductions of 9.5% and 19.2% for RO and 2.5% and 3.4% for ED at 5000 and 10,000 mg/L feed concentrations, respectively.
]]>Water doi: 10.3390/w16050793
Authors: Valentin Romanovski Andrei Paspelau Maksim Kamarou Vitaly Likhavitski Natalia Korob Elena Romanovskaia
Disinfection of surfaces with various functional purposes is a relevant measure for the inactivation of microorganisms and viruses. This procedure is used almost universally, from water treatment facilities to medical institutions and public spaces. Some of the most common disinfectants the World Health Organization recommends are chlorine-containing compounds. Sodium and calcium hypochlorites are only used for disinfection of the internal surfaces of water treatment facilities. However, it is known that ozone is a more powerful oxidizing agent. This study compares the effectiveness of inactivating yeast-like fungi Candida albicans, Gram-positive Bacillus subtilis, and Gram-negative bacteria Escherichia coli with aqueous ozone and sodium hypochlorite solutions. This study used ozone solutions in water with a concentration of 0.5–1.5 mg/L and sodium hypochlorite solutions with an active chlorine concentration of 50–150 mg/L. Steel and polymeric plates were used as substrates. Comparison of the CT (concentration by time) criterion at the ratio of LD50 in NaClO to ozonated water shows that the smallest difference, around 100 times, was observed in the inactivation of Candida albicans. The maximum difference is up to 230 times in the inactivation of Bacillus subtilis.
]]>Water doi: 10.3390/w16050792
Authors: Shangcong Zhang Yongfang Li Xuefei Chen Ruyi Zhou Ziran Wu Taha Zarhmouti
Fire pumps are the key components of water supply in a firefighting system. At present, there is a lack of fire water pump testing methods that intelligently detect faulty states. Existing testing approaches require manual operation, which leads to low efficiency and accuracy. To solve the issue, this paper presents an automatic and smart testing approach that acquires measurements of the flow, pressure, shaft power and efficiency from smart sensors via an IoT network, so that performance curves are obtained in the testing processes. An IoT platform is developed for data conversion, transmission and storage. The Discrete Fréchet Distance is applied to evaluate the similarities between the acquired performance curves and metric performance curves, to determine the working condition of the fire pump. The weights of the measurement dimensions for distance computation are optimized by the Genetic Algorithm to improve the distinction between normal and faulty performance curves. Finally, the experimental results show that the proposed method can completely detect faulty states and prove its high practicality for real firefighting systems.
]]>Water doi: 10.3390/w16050791
Authors: Lei Jin Shaodan Chen Mengfan Liu
Drought, as a recurring extreme climatic event, inflicts diverse impacts on ecological systems, agricultural productivity, water resources, and socio-economic progress globally. Discerning the drought patterns within the evolving environmental landscape of the Yellow River Basin (YRB) is imperative for enhancing regional drought management and fostering ecological conservation alongside high-quality development. This study utilizes meteorological drought indices, the Standardized Precipitation Evapotranspiration Index (SPEI) and the self-calibrating Palmer Drought Severity Index (scPDSI), for a detailed spatiotemporal analysis of drought conditions. It examines the effectiveness of these indices in the basin’s drought monitoring, offering a comprehensive insight into the area’s drought spatiotemporal dynamics. The findings demonstrate the following: (1) SPEI values exhibit distinct fluctuation patterns at varying temporal scales, with more pronounced fluctuations at shorter scales. Drought years identified via the 12-month SPEI time scale include 1965, 1966, 1969, 1972, 1986, 1997, 1999, 2001, and 2006. (2) A modified Mann–Kendall (MMK) trend test analysis of the scPDSI time series reveals a worrying trend of intensifying drought conditions within the basin. (3) Correlation analysis between SPEI and scPDSI across different time scales yields correlation coefficients of 0.35, 0.54, 0.69, 0.76, and 0.62, highlighting the most substantial correlation at an annual scale. Spatial correlation analysis conducted between SPEI and scPDSI across various scales reveals that, within diverse temporal ranges, the correlation peaks at a 12-month time scale, with subsequent prominence observed at 6 and 24 months. This observed pattern accentuates the applicability of scPDSI in the monitoring of medium- to long-term drought phenomena.
]]>Water doi: 10.3390/w16050790
Authors: Kun Yang Jinrui Yao Yin Huang Huiyan Ling Yu Yang Lin Zhang Diyun Chen Yuxian Liu
The river chief system (RCS) is an innovative reform in China for strengthening the management of rivers and lakes. It is an important means of curbing the current severe water-environment situation. However, the policy impact of the RCS is still inconclusive in the existing literature. Using monthly data spanning from January 2015 to March 2022 from 25 water quality monitoring stations in rivers flowing into the sea across 13 prefecture-level cities in Guangdong Province, this study adopted regression discontinuity to evaluate the policy effects of the RCS on water quality. The results show that after the RCS’s full implementation in Guangdong Province, the concentrations of dissolved oxygen (DO) increased and water quality indicators, such as permanganate index (CODMn), biochemical oxygen demand (BOD), ammonia nitrogen (NH3-N), chemical oxygen demand (COD), and total phosphorus (TP), decreased; NH3-N showed the largest decrease. These findings indicate that the RCS may contribute to a measurable improvement in reducing water pollution. However, no statistically significant changes in pH and total nitrogen (TN) were found, which indicates that the RCS fell short of achieving the policy effect of comprehensive water-pollution control. Therefore, in order to improve the RCS, it is necessary to refine the existing water-quality assessment indicators and to establish an evaluation system centered on the ecological health of rivers and lakes. Additionally, a paradigm shift from an administrative-boundary-based river management model to an overarching, holistic river-basin-based management approach is crucial for actualizing the holistic governance goals of the RCS.
]]>Water doi: 10.3390/w16050789
Authors: Jian Wang Ze Chen Linghao Li Chuan Wang Kangle Teng Qiang He Jiren Zhou Shanshan Li Weidong Cao Xiuli Wang Hongliang Wang
Submersible tubular pumps are an ideal choice for pump stations that require high flow rates and low lift. These pumps combine the unique features of submersible motors with axial flow pump technology, making them highly efficient and cost-effective. They have found extensive applications in China’s rapidly developing water conservancy industry. In this research, we focus on investigating the pressure pulsation characteristics of the internal bulb body in a specific pump station project in China. To conduct our analysis, we utilize a model of the submersible tubular pump and strategically position 18 monitoring points. These monitoring points cover various sections, including the impeller inlet and outlet, guide vane outlet, as well as the inlet, middle, and outlet sections of the bulb body segment. To calculate the unsteady flow of the system, we employ numerical simulation techniques. By combining the outcomes of model tests, we determine the pressure pulsation characteristics. The comparison of results reveals a remarkable similarity between the efficiency–head curves obtained from the numerical simulation and the model test. While the model test yields slightly higher head results, the numerical simulation indicates slightly higher efficiency values. This finding lends strong support to the reliability of numerical simulation results, which can provide valuable insights for the design and optimization of submersible tubular pumps. Overall, submersible tubular pumps demonstrate their suitability for pump stations with high flow rates and low lift requirements. The study of pressure pulsation characteristics within the bulb body contributes to a better understanding of their performance and facilitates their further application in the field of water conservancy engineering.
]]>Water doi: 10.3390/w16050788
Authors: Anthony A. Amori Olufemi P. Abimbola Trenton E. Franz Daran Rudnick Javed Iqbal Haishun Yang
Model calibration is essential for acceptable model performance and applications. The Hybrid-Maize model, developed at the University of Nebraska-Lincoln, is a process-based crop simulation model that simulates maize growth as a function of crop and field management and environmental conditions. In this study, we calibrated and validated the Hybrid-Maize model using soil moisture and yield data from eight commercial production fields in two years. We used a new method for the calibration and multi-parameter optimization (MPO) based on kriging with modified criteria for selecting the parameter combinations. The soil moisture-related parameter combination (SM-PC3) improved simulations of soil water dynamics, but improvement in model performance is still required. The grain yield-related parameter combination significantly improved the yield simulation. We concluded that the calibrated model is good enough for irrigation water management at the field scale. Future studies should focus on improving the model performance in simulating total soil water (TSW) dynamics at different soil depths by including more soil water processes in a more dynamic manner.
]]>Water doi: 10.3390/w16050787
Authors: Yongwei Gong Ge Meng Kun Tian Zhuolun Li
A proposed method for analyzing the effectiveness of rainwater storage tanks (RWSTs) based on various enabling rule scenarios has been proposed to address the issue of incomplete strategies and measures for controlling excessive rainwater runoff. Three enabling rules for RWSTs have been proposed, as follows: enabling rule I, which involves activation upon rainfall; enabling rule II, which requires the rainfall intensity to reach a predetermined threshold; and enabling rule III, which necessitates the cumulative rainfall to reach a set threshold. In order to assess the effectiveness of these enabling rules when reducing the total volume of rainwater outflow (TVRO), peak flow rate (PFR), and peak flow velocity (PFV), a comparative analysis was conducted to determine which enabling rule yielded the most optimal control effect. The findings indicate that the enabling rule I is responsible for determining the optimal unit catchment’s rainfall capture volume (UCRCV), which is measured at 300 m3·ha−1. Additionally, the control effect of the TVRO of the RWSTs remains largely unaffected by the peak proportion coefficient. Enabling rule II establishes the optimal activation threshold at a rainfall intensity of 1 mm·min−1; under this enabling rule, RWSTs demonstrate the most effective control over PFR and PFV. Enabling rule III enables the determination of the optimal activation threshold, which is set at a cumulative rainfall of 20 mm; under this enabling rule, the implementation of the RWST technique yields the most effective control over the TVRO. Consequently, the optimal rainwater runoff reduction plan for the study area has been successfully determined, providing valuable guidance for the implementation of scientific and reasonable optimal runoff management.
]]>Water doi: 10.3390/w16050786
Authors: Na Wang Lei Wang Liang Jin Jiajun Wu Min Pang Dan Wei Yan Li Junqiang Wang Ting Xu Zhixin Yang Jianzhi Xie
Rainfall intensity and slope gradient are the main drivers of slope surface runoff and nitrogen loss. To explore the distribution of rainfall runoff and nitrogen loss on the Miyun Reservoir slopes, we used artificial indoor simulated rainfall experiments to determine the distribution characteristics and nitrogen migration paths of surface and subsurface runoff under different rainfall intensities and slope gradients. The initial runoff generation time of subsurface runoff lagged that of surface runoff, and the lag time under different rainfall intensity and slope conditions ranges from 3.97 to 12.62 min. Surface runoff rate increased with increasing rainfall intensity and slope gradient; compared with a rainfall intensity of 40 mm/h, at a slope of 15°, average surface runoff rate at 60 and 80 mm/h increased by 2.38 and 3.60 times, respectively. Meanwhile, the subsurface runoff rate trended upwards with increasing rainfall intensity, in the order 5 > 15 > 10°. It initially increased and then decreased with increasing slope gradient, in the order 5 > 10 > 15°. Total nitrogen (TN) loss concentration of surface runoff shows a decrease followed by a stabilization trend; the concentration of TN loss decreases with decreasing rainfall intensity, and the stabilization time becomes earlier and is most obvious in 5° slope conditions. TN loss concentration in subsurface runoff decreased with increasing rainfall intensity, i.e., 40 > 60 > 80 mm/h. The surface runoff rainfall coefficient was mainly affected by rainfall intensity, a correlation between αs and slope gradients S was not obvious, and the fitting effect was poor. The subsurface runoff rainfall coefficient was mainly affected by slope gradient, the R2 of all rainfall intensities was <0.60, and the fitting effect was poor. The main runoff loss pathway from the Miyun Reservoir slopes was surface runoff, which was more than 62.57%. At the same time, nitrogen loss was subsurface runoff, more than 51.14%. The proportion of surface runoff to total runoff increases with the increase of rainfall intensity and slope, with a minimum of 62.57%, and the proportion of nitrogen loss from subsurface runoff also decreases with increasing rainfall intensity but does not change with slope gradient. The order of different runoff modulus types was mixed runoff (surface and subsurface runoff occur simultaneously) > surface runoff > subsurface runoff. The surface and mixed runoff modulus increased significantly with increasing rain intensity under different rain intensities and slope gradients. Overall, rainfall intensity significantly affected slope surface runoff, and slope gradient significantly affected nitrogen loss.
]]>Water doi: 10.3390/w16050785
Authors: Yongqi Liu Guibing Hou Baohua Wang Yang Xu Rui Tian Tao Wang Hui Qin
Flood control operation of cascade reservoirs is an important technology to reduce flood disasters and increase economic benefits. Flood forecast information can help reservoir managers make better use of flood resources and reduce flood risks. In this paper, a hierarchical pre-release flood operation rule considering the flood forecast and its uncertainty information is proposed for real-time flood control. A many-objective optimization model considering the cascade reservoir’s power generation objective, flood control objective, and navigation objective is established. Then, a region search evolutionary algorithm is applied to optimize the many-objective optimization model in a real-world case study upstream of the Yangtze River basin. The optimization experimental results show that the region search evolutionary algorithm can balance convergence and diversity well, and the HV value is 40% higher than the MOEA/D algorithm. The simulation flood control results of cascade reservoirs upstream of the Yangtze River demonstrate that the optimized flood control rule can increase the average multi-year power generation of cascade reservoirs by a maximum of 27.72 × 108 kWh under the condition of flood control safety. The rules proposed in this paper utilize flood resources by identifying runoff forecast information, and pre-release to the flood limit level 145 m before the big flood occurs, so as to ensure the safety downstream and the dam’s own flood control and provide reliable decision support for reservoir managers.
]]>Water doi: 10.3390/w16050784
Authors: Zhe Chen Wenying Yu Yingjian Zhan Zheng Chen Tengda Han Weiwei Song Yueyue Zhou
High concentrations of nitrite in marine aquaculture wastewater not only pose a threat to the survival and immune systems of aquatic organisms but also contribute to eutrophication, thereby impacting the balance of coastal ecosystems. Compared to traditional physical and chemical methods, utilizing microorganism-mediated biological denitrification is a cost-effective and efficient solution. However, the osmotic pressure changes and salt-induced enzyme precipitation in high-salinity seawater aquaculture environments may inhibit the growth and metabolism of freshwater bacterial strains, making it more suitable to select salt-tolerant marine microorganisms for treating nitrite in marine aquaculture wastewater. In this study, a salt-tolerant nitrite-degrading bacterium, designated as DM6, was isolated from the seawater (salinity of 25–30‰) of Portunus trituberculatus cultivation. The molecular identification of strain DM6 was conducted using 16S rRNA gene sequencing technology. The impacts of various environmental factors on the nitrite degradation performance of strain DM6 were investigated through single-factor and orthogonal experiments, with the selected conditions considered to be the key factors affecting the denitrification efficiency of microorganisms in actual wastewater treatment. PCR amplification of key genes involved in the nitrite metabolism pathway of strain DM6 was conducted, including denitrification pathway-related genes narG, narH, narI, nirS, and norB, as well as assimilation pathway-related genes nasC, nasD, nasE, glnA, gltB, gltD, gdhB, and gdhA. The findings indicated that strain DM6 is classified as Pseudomonas aeruginosa and exhibits efficient nitrite degradation even under a salinity of 35‰. The optimal nitrite degradation efficiency of DM6 was observed when using sodium citrate as the carbon source, a C/N ratio of 20, a salinity of 13‰, pH 8.0, and a temperature of 35 °C. Under these conditions, DM6 could completely degrade an initial nitrite concentration of 156.33 ± 1.17 mg/L within 36 h. Additionally, the successful amplification of key genes involved in the nitrite denitrification and assimilation pathways suggests that strain DM6 may possess both denitrification and assimilation pathways for nitrite degradation simultaneously. Compared to freshwater strains, strain DM6 demonstrates higher salt tolerance and exhibits strong nitrite degradation capability even at high concentrations. However, it may be more suitable for application in the treatment of wastewater from marine aquaculture systems during summer, high-temperature, or moderately alkaline conditions.
]]>Water doi: 10.3390/w16050783
Authors: Oanamari Daniela Orbuleţ Cristina Modrogan Cristina-Ileana Covaliu-Mierla
The objective of this study was to explore the removal of nitrate ions from groundwater by employing dynamic permeable reactive barriers (PRBs) with A400-nZVI. This research aimed to determine the parameters of the barrier and evaluate its overall capacity to retain nitrate ions during percolation with a potassium nitrate solution. The process involves obtaining zerovalent iron (nZVI) nanoparticles, which were synthesized and incorporated onto an anionic resin support material (A400) through the reduction reaction of ferrous ions with sodium borohydride (NaBH4). This is achieved by preparing a ferrous sulfate solution, contacting it with the ion exchange resin at various solid–liquid mass ratios and gradually adding sodium borohydride under continuous stirring in an oxygen-free environment to create the A400-nZVI barrier. The results of the study, focusing on the development of permeable reactive barriers composed of nano zero-valent iron and ion exchangers, highlight the significant potential of water treatment processes when appropriately sized. The research specifically assesses the effectiveness of NO3− removal by using the A400-nZVI permeable reactive barrier, conducting laboratory tests that simulate a naturally stratified aquifer with high nitrate contamination.
]]>Water doi: 10.3390/w16050782
Authors: Tangwu Yang Dianpeng Li Qing Xu Yijia Zhu Zhengjie Zhu Xin Leng Dehua Zhao Shuqing An
Long-term fishing bans have spurred extensive debate regarding their impacts on ecosystem structures, functions, and water qualities. However, data on the effects of specific changes induced by fishing bans on ecosystem structures, functions, and water qualities in lakes are still lacking. Therefore, the present study addresses this knowledge gap by employing an Ecopath model to assess alterations in an ecosystem’s structure and function before (2011) and after (2021) the implementation of the fishing ban in Caohai Lake and its association with changes in water quality. (1) We observed a substantial reduction in the area covered by submerged aquatic vegetation after the ban, amounting to a 65% decrease in coverage compared with that before the ban, and a 60% reduction in the total ecosystem’s biomass. (2) Following the ban, the number of fish species increased from 7 to 14, and this was accompanied by a rise in the fish biomass from 14.16 t·km−2 to 25.81 t·km−2; a 4.5-fold increase in the total system consumption was observed, signifying accelerated energy and material flows within the ecosystem. (3) The fishing ban exhibited no significant impact on the total nitrogen concentration; however, it significantly reduced the water’s transparency and increased the total phosphorus, ammonia nitrogen, chemical oxygen demand, and chlorophyll contents (p < 0.05). This shift in nutrient dynamics fostered a transformation from a macrophyte-dominant lake to an alga-dominant lake. The fish abundance and diversity increase in closed-type macrophytic lakes, thereby accelerating energy and material flows within food webs. These findings present novel insights into the effective policy management of fishing bans within the Yangtze River Basin, thus enhancing our understanding of sustainable lake ecosystem management.
]]>Water doi: 10.3390/w16050781
Authors: João Lincho João Gomes Rui C. Martins Eva Domingues
Swine wastewater (SW) was treated using industrial wastes as raw materials in a pre-treatment process (coagulation or adsorption), followed by a continuous heterogeneous Fenton reaction. Before the treatment conducted as a continuous operation, two different batch optimization strategies were evaluated, in which the effects of H2O2 concentration and pH were studied. The results show that using excessive H2O2 results in the same behavior, regardless of whether the pH is 3 or 7.5, while at low H2O2 concentrations, the acidic pH improves the chemical oxygen demand (COD) removal due to a higher solubility of iron. The partial addition of H2O2 after 60 min of the reaction proved to be unbeneficial. Considering other perspectives, a continuous Fenton process using iron filings (IF) as the iron source ([H2O2] = 50 mg/L) was applied after the SW pre-treatment, consisting of adsorption with red mud (RM) or coagulation with poly-diallyldimethylammonium chloride (PDADMAC). The RM adsorption presented higher COD removal and lower toxicity than the PDADMAC coagulation, revealing to be a suitable material for this purpose, but for both pre-treatments, the application of a subsequent continuous Fenton process revealed to be essential to achieve the COD discharge limits imposed by the Portuguese law. In addition, high amounts of dissolved iron were present in the samples (55–58 mg/L) after the Fenton process. However, after the overall treatment, the samples showed no harmful characteristics for Lepidium sativum, being classified as “non-toxic”, contrary to the initial wastewater.
]]>Water doi: 10.3390/w16050780
Authors: Thiago dos Santos Gonçalves Harald Klammler Luíz Rogério Bastos Leal
Aquifer properties, such as hydraulic transmissivity T and its spatial variability, are fundamental for sustainable groundwater exploitation in arid regions. Especially in karst aquifers, spatial variability can be considerable, and the application of geostatistical methods allows for spatial interpolation and mapping based on observations combined with the quantification of uncertainties. Moreover, direct measurements of T are typically scarce, while those of specific capacity Sc are more frequent. In this study, we establish the linear regression relationship between the logarithms of T and Sc measured in 51 wells in a semi-arid karst region in Northeastern Brazil. This relationship is used to estimate empirical values logTemp based on measurements of logSc at 269 wells. LogTemp values are found to be normally distributed with an isotropic variogram of a significant nugget effect (attributed to local-scale karst features) and approximately 10 km range (attributed to larger-scale gradual changes in karst feature density). Ordinary kriging cross-validation indicates an optimum number of 25 neighboring wells for interpolation, which is used in a conditional sequential Gaussian simulation (SGSIM) to generate 500 realizations of logTemp with respective maps of standard deviations and probabilities of (not) exceeding threshold values. High-transmissivity areas mostly coincide with karstified river valleys, while low-transmissivity areas occur toward the edges where aquifer thickness decreases. The resulting transmissivity maps are relevant for optimizing regional water management strategies, which includes stochastic approaches where transmissivity realizations can be used to parameterize multiple runs of numerical groundwater models.
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