Water

Nowadays, many major copper mining projects in desert areas with extremely dry climates, as in northern Chile and the southern coast of Peru, process sulfide ores at high production rates; in some cases over 100,000 metric tonnes per day (mtpd), generating large amounts of tailings, that are commonly managed and transported to tailings storage facilities (TSF) hydraulically using fresh water. Considering the extremely dry climate, water scarcity, community demands, and environmental constraints in these desert areas, the efficient use of water in mining is being strongly enforced. For this reason, water supply is recognized as one of the limiting factors for the development of new mining projects and for the expansion of the existing ones in these areas. New water supply alternatives, such as sea water desalinization, direct use of sea water, or water recovery from tailings, represent the strategy developed by the mining industry to deal with this growing scarcity. The focus of this paper is the possibility of applying different water supply technologies or a combination of these, implementing improved water management strategies that consider: environmental issues, technical issues, stringent regulatory frameworks, community requests and cost-effective strategies, that result in a reduction of freshwater make-up water requirements for mining (m³ per metric tonnes of treated ore). Full article

The nonlinear flow law and soil boundaries greatly affect the dissipation process of soil consolidation. Thus, to study the impact of nonlinear flow under impeded drainage boundaries, the classical non-Darcian flow model described by non-Newtonian index was introduced. The numerical solutions are derived in detail by the finite difference method (FDM) for one-dimensional (1-D) consolidation incorporating the impeded boundaries, and the computer program is compiled. Then, comparing two analytical solutions based on Darcy’s law and a numerical case of Forchheimeer’s flow, the validity of the present method was verified. The numerical results indicate that there is a critical depth phenomenon for the non-Darcian flow incorporating impeded drainage boundaries. The excess pore water pressure of the soil below the critical depth dissipates more slowly than that of Darcy’s law, whereas the pore pressure of the soil above the critical depth dissipates more quickly than that of Darcy’s law. Moreover, considering that the non-Darcian flow with the non-Newtonian index will still delay the overall consolidation rate of the soft ground, the greater the nondimensional parameter I₀ is, the more obvious the lagging phenomenon of the overall dissipation of pore pressure is. Full article

Microcystis-dominated cyanobacterial harmful algal blooms (cyanoHABs) are a reoccurring problem globally, resulting in widespread economic and health impacts. As public awareness of the risks of blooms increases, there is an urgent need for studies on both short-term and long-term management of cyanoHABs. In order to provide science-based best management practices and treatment options, we tested various concentrations and combinations of USEPA-registered algaecides and herbicides on a Microcystis wesenbergii-dominated bloom. The bloom material was exposed to fifteen different algaecides, herbicides, or combinations, using four different concentrations. Cell abundance and morphology as well as microscopic analyses were undertaken at the time of collection and 72 h post-treatment. Overall, the effectiveness of the chemicals varied with the most efficacious treatments being SeClear^®, and a combination of Hydrothol^® 191 and GreenClean^® Liquid 5.0, both of which resulted in a significant decrease at all tested concentrations after 72 h. Interestingly, Microcystis wesenbergii is more resistant to algaecides than M. aeruginosa. Results from this study provide valuable data for treating cyanoHABs and show the varied efficacy of different algaecidal formulations. Full article

Facing the conflict between human activities and the ecological environment, this study proposes a “Virtuous Cycle” concept of water resource management and top-level planning. By analyzing and summarizing typical experiences from both macro-policy and micro-practice, the characteristics and mechanisms of the Virtuous Cycle are discussed. According to the analysis method of “Problem-Attribution-Goal-Task-Measures” (PAGTM), taking the “Five Water Governance” water management project in Zhejiang Province of China as a case study, the specific measures and technical framework of the Virtuous Cycle are explored. This study hopes to provide a reference for the top-level planning and path design of harmonious and sustainable natural-social water resources management. Full article

Microplastics (MPs) are an emerging pollutant in the aquatic environment, and this has gradually been recognized in the Asian region. This systematic review study, using the Scopus database, provides an insightful understanding of the spatial distribution of scientific studies on MPs in freshwater conducted across the Asian region, utilized sampling methods, and a detailed assessment of the effects of MPs on different biotic components in freshwater ecosystems, with special focus on its potential risks on human health. The results of this review indicate that research on microplastics in Asia has gained attention since 2014, with a significant increase in the number of studies in 2018, and the number of scientific studies quadrupled in 2021 compared to 2018. Results indicated that despite a significant amount of research has been conducted in many Asian countries, they were not distributed evenly, as multiple studies selected specific rivers and lakes. Additionally, around two-thirds of all the papers focused their studies in China, followed by India and South Korea. It was also found that most of the studies focused primarily on reporting the occurrence levels of MPs in freshwater systems, such as water and sediments, and aquatic organisms, with a lack of studies investigating the human intake of MPs and their potential risks to human health. Notably, comparing the results is a challenge because diverse sampling, separation, and identification methods were applied to estimate MPs. This review study suggests that further research on the dynamics and transport of microplastics in biota and humans is needed, as Asia is a major consumer of seafood products and contributes significantly to the generation of plastic litter in the marine environment. Moreover, this review study revealed that only a few studies extended their discussions to policies and governance aspects of MPs. This implies the need for further research on policy and governance frameworks to address this emerging water pollutant more holistically. Full article

Taiwan’s near-mountain alluvial plain is a high-risk area with frequent disasters, and residents have become more tolerant of the compound disasters that occur with overall environmental changes associated with the development of urbanization in recent years. This paper presents a case study of a near-mountainous alluvial plain in Southern Taiwan. The Hakka ethnic group is the main community in the study area and also the main research object. This case study illustrates the disaster resilience of the community to natural and artificial disasters. This study adopted two research approaches, namely historical geography and political economic geography, as well as community resilience theory. Research methods including case study, secondary literature analysis, fieldwork, and interviews were used. Through text analysis, it was found that (1) the community’s awareness of disaster avoidance was rooted in the experience of reclamation in the early 17th century; (2) communities have experienced artificial disasters caused by political and economic intervention, which have been transformed into disaster awareness and community resilience; (3) cumulative artificial disasters have a greater impact on communities than unpredictable natural disasters; and (4) the energy of community resilience and agricultural regeneration is based on the duality of disasters. Full article

This study created a framework for assessing the spatial and temporal distribution of the supply and demand of four potential produced water (PW) reuse options: agriculture, dust suppression, power generation, and river flow augmentation using Eddy and Lea counties in the southeastern New Mexico Permian Basin as a case study. Improving the PW management in the oil and gas industry is important in areas with limited water resources and increasing restrictions on PW disposal. One option in the PW management portfolio is fit-for-purpose reuse, but a lack of adequate information on PW quality, volumes, and the spatiotemporal distribution of PW supply and demand precludes its reuse. Using the framework, we determined that a 1.1-mile grid cell for data aggregation is a sufficient spatial scale for capturing the granular data needed for PW management decisions. The annual available PW supply for the two counties was estimated to be 45,460,875 m³ (36,870 acre-feet). The annual cumulative estimated demand was 647,656,261 m³ (525,064 acre-feet) for the four potential use cases—far exceeding PW supply. The maps generated using the framework illustrated that much of the supply and demand are spatially dispersed. The spatiotemporal analysis framework provides a generic methodology that can be used for PW management in other basins or for assessing alternative waters at the local and regional scales where management occurs. Full article

A multiphase extension of the δ-plus-SPH (smoothed particle hydrodynamics) model is developed for modeling non-Newtonian multiphase flow. A modified numerical diffusive term and special shifting treatment near the phase interface are introduced to the original δ-plus-SPH model to improve the accuracy and numerical stability of the weakly incompressible SPH model. The Herschel–Bulkley model is used to describe non-Newtonian fluids. A sub-particle term is added in the momentum equation based on a large eddy simulation. The graphic processing unit (GPU) acceleration technique is applied to increase the computational efficiency. Three test cases including, a static tank, Poiseuille flow, and submarine debris flow, are presented to assess the performance of the new multiphase SPH model. Comparisons with analytical solutions, experimental data, and previous numerical results indicate that the proposed SPH model can capture highly transient incompressible two-phase flows with consistent pressure across the interface. Full article

Climate change includes the change of the long-term average values and the change of the tails of probability density functions, where the extreme events are located. However, obtaining average values are more straightforward than the high temporal resolution information necessary to catch the extreme events on those tails. Such information is difficult to get in areas lacking sufficient rain stations. Thanks to the development of Satellite Precipitation Estimates with a daily resolution, this problem has been overcome, so Extreme Precipitation Indices (EPI) can be calculated for the entire Colombian territory. However, Colombia is strongly affected by the ENSO (El Niño—Southern Oscillation) phenomenon. Therefore, it is pertinent to ask if the EPI’s long-term change due to climate change is more critical than the anomalies due to climate variability induced by the warm and cold phases of ENSO (El Niño and La Niña, respectively). In this work, we built EPI annual time series at each grid-point of the selected Satellite Precipitation Estimate (CHIRPSv2) over Colombia to answer the previous question. Then, the Mann-Whitney-Wilcoxon test was used to compare the samples drawn in each case (i.e., change tests due to both long-term and climatic variability). After performing the analyses, we realized that the importance of the change depends on the region analyzed and the considered EPI. However, some general conclusions became evident: during El Niño years (La Niña), EPI’s anomaly follows the general trend of reduction -drier conditions- (increase; -wetter conditions-) observed in Colombian annual precipitation amount, but only on the Pacific, the Caribbean, and the Andean region. In the Eastern plains of Colombia (Orinoquía and Amazonian region), EPI show a certain insensitivity to change due to climatic variability. On the other hand, EPI’s long-term changes in the Pacific, the Caribbean, and the Andean region are spatially scattered. Still, long-term changes in the eastern plains have a moderate spatial consistency with statistical significance. Full article

Inland waters are dynamic systems that are under pressure from anthropogenic activities, thus constant observation of these waters is essential. Remote sensing provides a great opportunity to have frequent observations of inland waters. The aim of this study was to create a data-driven model that uses a machine learning algorithm and Sentinel-2 data to classify lake observations into four biophysical classes: Clear, Moderate, Chla-dominated, and Turbid. We used biophysical variables such as water transparency, chlorophyll concentration, and suspended matter to define these classes. We tested six machine learning algorithms that use spectral features of lakes as input and chose random forest classifiers, which yielded the most accurate results. We applied our two-step model on 19292 lake spectra for the years 2015–2020, from 226 lakes. The prevalent class in 67% of lakes was Clear, while 19% of lakes were likely affected by strong algal blooms (Chla-dominated class). The models created in this study can be applied to lakes in other regions where similar lake classes are found. Biophysical lake classification using Sentinel-2 MSI data can help to observe long-term and short-term changes in lakes, thus it can be a useful tool for water management experts and for the public. Full article

Due to the complexity of calculating the minimum required volume of water tanks and the associated regime of pumping water into the tank depending on the consumption pattern in the water supply systems, finding the functional dependence of these variables is a complex process. The main idea of this paper was to provide a methodology for the calculation of the minimum water tank volume considering all input variables, which could be used in a simple and applicable way in everyday water supply management and engineering. As a final product, a desktop application TankOPT was developed that is easy to run and use on a PC with a user-friendly interface for data entry (data on maximum daily consumption and the pattern of daily water consumption). A software solution was created based on a numerical model that simplifies the usual manual calculations using known spreadsheet software and solves this problem. The solution was determined with combinations of the start and duration of water pumping in the water tank, for which the minimum required volume of the tank is obtained. JavaScript programming language was used to create the app. The use and operation of the application are shown through two hypothetical examples. Full article

In order to explore the internal relationship between stall core propagation and flange leakage flow in the rotating stall of a mixed-flow pump, based on the k-ε turbulence model, a SIMPLEC algorithm and hexahedral structured grid are used to simulate the internal flow field of the mixed-flow pump. By setting the flange clearance as 0.2 mm, 0.5 mm and 0.8 mm, the propagation characteristics of the rotating stall and the unsteady characteristics of flange leakage flow of the mixed-flow pump under the condition of near stall are studied, and the influence of the flange clearance on the pressure fluctuation characteristics of the mixed-flow pump under the condition of near stall is analyzed. The results show that the stall core is located at the outlet of the impeller and propagates from the leading edge of the adjacent blade along the opposite direction of blade rotation to the next flow channel. The pressure gradient in the stall channel and the energy loss are large . When the flange clearance is 0.5 mm and 0.8 mm, the stall core changes from one to two, and the propagation mechanism of the stall core tends to be complex in the two adjacent flow channels. When the flange clearance is 0.8 mm, the propagation period decreases. The variation law of leakage flow is consistent with the propagation law of stall core. When the flow passage changes from stall state to non-stall state, the leakage flow also changes from one state to another, so the leakage flow can be used as a form of apparent stall. Under the condition of near stall, the pressure fluctuation curve of the adjacent monitoring points has a large phase difference consistent with the propagation period of the stall core, and has a strong pressure drop. When the flange clearance is 0.5 mm and 0.8 mm, the time domain curve of pressure fluctuation has two wave troughs in one cycle. In the near stall condition, the main frequency of the pressure fluctuation at the monitoring point is the stall frequency, and the amplitude of the main frequency at the middle of the outlet is the largest. The characteristics of flange leakage flow and pressure fluctuation can better reflect the flow situation in the pump when rotating stall occurs. The research results can provide a basis for judging whether stall occurs in the flow passage of the pump. Full article

The hydraulic conductivity of saturated soil is a crucial parameter in the study of any engineering problem concerning groundwater. Hydraulic conductivity mainly depends on particle size distribution, soil compaction, and properties that influence aggregation and water retention. Generally, finding simple and accurate analytical equations between the hydraulic conductivity of soil and the characteristics on which it depends is a very hard task. Machine learning algorithms can provide excellent tools for tackling highly nonlinear regression problems. Additionally, hybrid models resulting from the combination of multiple machine learning algorithms can further improve the accuracy of predictions. Five different models were built to predict saturated hydraulic conductivity using a dataset extracted from the Soil Water Infiltration Global database. The models were based on different predictors. Seven variants of each model were compared, replacing the implemented algorithm. Three variants were based on individual models, while four variants were based on hybrid models. The employed individual machine learning algorithms were Multilayer Perceptron, Random Forest, and Support Vector Regression. The model based on the largest number of predictors led to the most accurate predictions. In addition, across all models, hybrid variants based on all three algorithms and hybridized variants of Random Forest and Support Vector Regression proved to be the most accurate (R² values up to 0.829). However, all variants showed a tendency to overestimate conductivity in soils where it is very low. Full article

The improved understanding of the behavior of antibiotics in soil is of great importance due to their environmental hazard and frequent detection. In this work, the adsorption-desorption and mobility behaviors of ciprofloxacin in sandy silt soil, affecting the fate of ciprofloxacin in the environment, were studied by a series of batch tests and column tests. In batch tests, the effects of contact time, initial ciprofloxacin concentration, sandy silt soil dosage, solution pH, and ionic strength on ciprofloxacin adsorption and desorption in sandy silt soil were considered. Adsorption results were satisfactorily modeled, with good fittings to the pseudo-second-order model (R² > 0.999) and Langmuir model (R² >0.991), with the value for Langmuir’s maximum adsorption capacity (q_m) 5.50 mg g⁻¹. Ciprofloxacin adsorption decreased sharply by increasing the pH from 7.0 to 10.0 and the ionic strength from 0.01 to 0.2 mol L⁻¹ CaCl₂. Comparatively, ciprofloxacin was more readily desorbed from sandy silt soil at alkaline and high ionic strength conditions. Breakthrough curves of ciprofloxacin obtained from the column experiments were described by the two-site model, Thomas model, and Yan mode. Of these models, the two-site model was the most suitable to describe the mobility of ciprofloxacin. The retardation factor (R) obtained in the two-site model was 345, suggesting strong adsorption affinity with ciprofloxacin on the sandy silt soil surface. The results from the Thomas model suggested the extremely small external and internal diffusion resistances. The Yan model was not suitable. Cation exchange interaction, electrostatic interaction, mechanical resistance, entrapment between porous media, and gravity sedimentation were proposed to be the important adsorption mechanisms. Full article

Intense “blooming” of cyanobacteria (blue-green algae) caused by eutrophication and climate change poses a serious threat to freshwater ecosystems and drinking water safety. Preventing the proliferation of cyanobacteria and reducing water nutrient load is a priority for the restoration of eutrophic water bodies. Aquatic plants play an important role in the function and structure of aquatic ecosystems, affecting the physiochemistry of the water and bottom sediments, primary production, and biotic interactions that support a balanced ecosystem. This review examines the inhibitory effect of aquatic vascular plants on harmful blooms of cyanobacteria. Aquatic plants are able to successfully inhibit the growth of cyanobacteria through various mechanisms, including by reducing nutrient and light availability, creating favorable conditions for the development of herbivorous zooplankton, and releasing allelopathic active substances (allelochemicals) with algicidal effect. Allelopathy is species-specific and therefore acts as one of the key mechanisms by which the development of cyanobacterial populations in aquatic ecosystems is regulated. However, allelopathic activity of aquatic vascular plants depends on various factors (species characteristics of aquatic plants, area, and density of overgrowth of water bodies, physiochemical properties of allelopathically active substances, hydrological and hydrochemical regimes, temperature, light intensity, etc.), which may regulate the impact of allelochemicals on algal communities. The paper also discusses some problematic aspects of using fast-growing species of aquatic vascular plants to control cyanobacterial blooms. Full article

The secondary effluent of the wastewater treatment plant is considered as one of the reused water sources and needs advanced treatment to meet increasingly stringent water treatment standards. Ultrafiltration, as one of the most widely used advanced treatment technologies, is limited due to membrane fouling, and coagulation and pre-oxidation have received extensive attention as pretreatment methods to alleviate membrane fouling. This research proposes a new method of Fe(II)-activated peroxymonosulfate (PMS) coagulation and a pre-oxidation system coupled with ultrafiltration (UF) to treat secondary effluent from sewage plants, separately evaluating the treatment effect under different molar ratios of Fe(II)/PMS. The Fe(II)/PMS decontamination mechanism and membrane fouling control effect were elucidated through pollutant removal efficiency, membrane morphology, membrane flux trend, and membrane fouling resistance distribution. According to the experimental results, the optimal effect of organic matter removal and membrane fouling mitigation was achieved at the Fe(II)/PMS dosage of 60/60 μM/μM (molar ratio 1:1). The efficiency of pretreatment methods in removing organics and fluorescent components and mitigating membrane fouling followed the order of Fe(II)/PMS > Fe(III) > inactivated PMS. Fe(II)/PMS could produce a synergistic effect in a high concentration state (60 μM), relying on the dual effects of coagulation and oxidation to alleviate membrane fouling. Coagulation and pre-oxidation by Fe(II)/PMS significantly reduced the clogging of membrane pores and the proportion of irreversible resistance, effectively controlling membrane fouling and improving effluent quality. SEM images further confirmed its effectiveness, and EPR results unequivocally indicated that its synergistic mechanism was mediated by •OH and SO₄^•−. The research results can provide ideas for advanced wastewater treatment and secondary effluent reuse. Full article

Coastal areas are characterized by considerable demographic pressure that generally leads to groundwater overexploitation. In the Mediterranean region, this situation is exacerbated by a recharge reduction enhanced by climate change. The consequence is water table drawdown that alters the freshwater/seawater interface facilitating seawater intrusion. However, the groundwater salinity may also be affected by other natural/anthropogenic sources. In this paper, water quality data gathered at 47 private and public wells in a coastal karst aquifer in Apulia (southern Italy), were interpreted by applying disparate methods to reveal the different sources of groundwater salinity. Chemical characterization, multivariate statistical analysis, and mixing calculations supplied the groundwater salinization degree. Characteristic ion ratios, strontium isotope (⁸⁷Sr/⁸⁶Sr), and pure mixing modelling identified the current seawater intrusion as a main salinity source, also highlighting the contribution of water–rock interaction to groundwater composition and excluding influence from Cretaceous paleo-seawater. Only the combined approach of all the methodologies allowed a clear identification of the main sources of salinization, excluding other less probable ones (e.g., paleo-seawater). The proposed approach enables effective investigation of processes governing salinity changes in coastal aquifers, to support more informed management. Full article

Understanding the effect of flooding on groundwater quality is imperative for oasis vegetation protection and local ecological environment development. We used geochemical and remote sensing inversion methods to evaluate the effects of flood recharge on the groundwater hydrochemical and geochemical processes in the Daliyaboy Oasis. Groundwater samples were collected from 30 ecological observation wells in the study area before (PRF) and after (POF) the flood. Except for small changes in HCO₃⁻ and K⁺ and a decrease in pH, ion levels were higher POF than PRF, and the water chemistry was essentially unchanged. In the POF groundwater, HCO₃⁻ was correlated with Cl⁻, Na⁺, Mg²⁺, total soluble solids (TDS), and electrical conductivity (EC), but not with SO₄²⁻, Ca²⁺, K⁺, or pH, and was positively correlated with all other variables, while the remaining variables, except for pH, were strongly positively correlated with each other. PRF water chemistry was controlled by silicate and evaporite mineral weathering and evaporation processes, resulting in high groundwater TDS, EC, and a major ion content, while POF major groundwater ions were regulated by mineral weathering and flood recharge. We demonstrated the high accuracy of remote sensing inversion, confirming this as a reliable method for evaluating groundwater chemistry. The results of the study help to reshape and predict the history of the regional hydrogeological environment and hydrogeochemical development, and provide a theoretical basis for assessing the rational use of local water resources and protecting the ecological environment. Full article

The Pearl River is a global hotspot of fish biodiversity, yet has the most threatened endemic fish species in China. Since the establishment of the Changzhou Dam in the lower reach, changes in hydrological rhythm have negatively impacted fish downstream of the dam, but their spatiotemporal distribution in response to flood alteration has received little attention. In this study, hydroacoustic surveys were undertaken monthly in 2016 to monitor the distribution and behavior of fish. Fish densities were higher during the water discharge rising stage than during the falling stage, indicating that the fish aggregate during flooding (coefficient of variation [CV] > 100%) and depart after flooding (CV < 100%), especially aggregations of large fish. The target strength (TS) was allocated to two groups as per their frequency distributions, defined as small fish (−55 dB < TS < −40 dB) and large fish (TS > −40 dB). The sizes of both groups were significantly larger during the rising stage when compared to those during the falling stage (p < 0.01). Comparatively more fish were present with a greater average TS, and a substantially greater proportion of large fish was detected during rising stages. Hydrological variation importantly influences fish aggregations, including the numbers and sizes present, with the differences being particularly pronounced between the rising and falling stages. Combined with relevant studies, it is suggested that water releases from the Changzhou Dam should be regulated to satisfy fish spawning and migration demands during the main breeding season. Full article