Water, Volume 15, Issue 13 (July-1 2023) – 195 articles

Artisanal and small-scale gold mining activities have an impact on natural resources and human health. This study addresses the assessment of surface water quality in the Lom gold basin. A combined approach of water quality index calculation, multivariate statistical analysis and spatial interpolation was used. Sampling was performed at 15 stations during low- and high-water periods in 2021 for classical physicochemical parameters and total mercury measurements. The results show that the physicochemical parameters were below drinking water standards for both periods, except for pH, total suspended solids and total mercury. These waters show a large cation deficit as well as an anion deficit. The water chemistry is controlled by precipitations and silicate dissolutions in rock that convert the water into the Ca-HCO₃ and Ca-Mg-HCO₃ types. The level of mercury contamination varied from acceptable to high due to high flow rates during high water that cause a dilution effect for the mercury concentration upstream and its accumulation downstream. The water quality varied from excellent to very poor with better quality during the high-water period. The Lom watershed is locally affected by physical and chemical pollution due to the abundance of suspended solids and mercury resulting from the different gold mining activities. Full article

This paper presents a comprehensive review of optimization algorithms utilized in reservoir simulation-optimization models, specifically focusing on determining optimal rule curves. The study explores critical conditions essential for the optimization process, including inflow data, objective and smoothing functions, downstream water demand, initial reservoir characteristics, evaluation scenarios, and stop criteria. By examining these factors, the paper provides valuable insights into the effective application of optimization algorithms in reservoir operations. Furthermore, the paper discusses the application of popular optimization algorithms, namely the genetic algorithm (GA), particle swarm optimization (PSO), cuckoo search (CS), and tabu search (TS), highlighting how researchers can utilize them in their studies. The findings of this review indicate that identifying optimal conditions and considering future scenarios contribute to the derivation of optimal rule curves for anticipated situations. The implementation of these curves can significantly enhance reservoir management practices and facilitate the resolution of water resource challenges, such as floods and droughts. Full article

Harmful algal blooms (HABs) are overgrowths of toxic strains of algae (diatoms, green) and cyanobacteria (blue-green algae). While occurring naturally, human-induced environmental changes have resulted in more frequent occurrences of such blooms worldwide. Meantime, the ecotoxicological risk of HABs is rarely evaluated by means of standard test methods. For the first time, the genotoxic potential of the HAB event 2020 was assessed using two different Tradescantia-based test systems (Trad-SHM and Trad-MN, 24-h exposure). An integrated analysis of biological (algal abundance) and ecotoxicological (testing) data revealed linkages among algal proliferation, changes in Tradescantia stamen hairs (mutations and suppressed growth) and chromosomal aberrations during microsporogenesis (appearance of micronuclei) that were likely to be caused by toxic algal groups. Green alga Botryococcus braunii and the cyanobacterial species Anabaena and Oscillatoria could suppress stamen hair growth; Cyanobacteria Phormidium and Aphanothece sp. could trigger mutations in stamen hairs (appearance of pink and colorless cells); and Oscillatoria sp. could be responsible for the occurrence of chromosomal damage. Diatom proliferation in the spring was not related to the genotoxic response in Tradescantia. Both tests, the Trad-SHM and Trad-MN, are suitable for the evaluation of the toxic potential of HABs. Full article

Sodium hypochlorite (NaClO) solution is wildly used to remove membrane fouling-derived organic materials and restore membrane flux, which can result in the formation of halogenated by-products. To reduce the halogenated by-products, a combined cleaning process with NaClO and peroxides including hydrogen peroxide (H₂O₂), peroxydisulfate (PDS), and peroxymonosulfate (PMS) were applied in offline mode to remove the organic fouling. It was found that all the combined cleaning processes could effectively restore the membrane flux. Compared with the process of NaClO cleaning followed by peroxide cleaning (NaClO–peroxide), fewer halogenated by-products were generated in the NaClO post-combined cleaning process (peroxide–NaClO), and the PDS–NaClO cleaning process exhibited the best performance in controlling by-products. Overall, most by-product generation showed a positive correlation with reaction time and temperature. Full article

Malaysia has numerous policies, institutions, and experts with foresight and vision for its development. Nevertheless, river basin management has been lacking due to several factors such as insufficient proactive leadership roles of institutions, as well as locally authorized bodies. Reviewing of stakeholders’ role in the PENTA-HELIX partnership model (i.e., government, business, academia, community, and NGO) reveals that individuals and institutions with proactive and effective leadership roles along with top-down and bottom-up approaches can create a more strategic policy implementation resulting in better outcomes in river basin management. Local authorities with proactive leadership roles should be encouraged to use a creative and innovative key performance indicator system accompanied by mentoring and training, as well as education, to inspire a passive to active attitude change. A local authority with sound leadership roles can develop proper partnerships with its many stakeholders to improve awareness with more multitasking activities. These can be achieved by motivating all the related stakeholders towards more commitment to creating a sustainable environment. Identifying and recognizing local authorities to manage the rivers will result in more powerful actions in river management. It is essential to ensure quality control and quality assurance at various levels to bring sustainability science at the multi-stakeholders’ platforms towards an integrated river basin management to achieve a better living quality for everyone. Full article

This research investigates the views of the resettled people regarding the practice of resettlement and compensation (RCP) to assess the developmental progress of the Tha Htay hydropower (THH) project and establish a resettlement relationship from various perspectives. In this paper, a convergent mixed research method was used for interpretations and analyses of the whole resettlement and compensation practice. Descriptive statistics were utilized to analyze the collected data on the resettlement practices of those participants who presented it by frequency and percentage of quantitative findings. The study revealed that educational facilities and development received the highest average rating from the participants, indicating a higher level of satisfaction. On the other hand, the current living situation and job opportunities received the lowest rating, indicating lower satisfaction in this aspect. Overall, the respondents expressed satisfaction with other indicators of the resettlement process, such as site selection, housing, compensation, and fundamental infrastructure services. Despite receiving foreign technical advisory assistance for resettlement and sustainable livelihoods for the resettled communities, the project fell short in providing agricultural or cultivation land as a replacement for those who relied on land-based livelihoods. It was verified that most of the resettled people seemed poorer than in the previous condition, and they were facing higher living standards without adequate income. It is therefore crucial for the project proponent to take active measures in supporting the three resettled Villages by providing agricultural land and assisting them in their livelihoods and overall living conditions, so as to ensure that the resettled households do not face long-term challenges in sustaining their livelihoods after the resettlement project. Full article

The utilization of wastewater as a community surveillance method grew during the COVID-19 epidemic. COVID-19 hospitalizations are closely connected with wastewater viral signals, and increases in wastewater viral signals can serve as an early warning indication for rising hospital admissions. While reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) is the most often used approach for detecting SARS-CoV-2 in wastewater, chemiluminescence enzyme immunoassay (CLEIA) is an alternative automated method. In two assays, 92 wastewater grab samples from a hospital were investigated for the presence of SARS-CoV-2, expected for continuous and monitoring SARS-CoV-2 surveillance. One was in the RT-qPCR nucleic acid test, and another was in the CLEIA assay quantitative antigen test. In 24/92 (26.09%) of the wastewater samples, RT-qPCR identified at least two SARS-CoV-2 genes (ORF1ab, N, or S genes). CLEIA, on the other hand, detected SARS-CoV-2 antigen in 39/92 (42.39%) of the samples. CLEIA demonstrated a low sensitivity and specificity of sensitivity of 54.2% (95% CI: 44.0–64.3%) and 61.8% (95% CI: 51.8–71.7%), respectively, as compared to RT-qPCR. The κ coefficient indicated slight agreement between assay. Then, the CLEIA assay cannot replace molecular-based testing like RT PCR for determining SARS-CoV-2 in hospital wastewater. Full article

Heavy metal pollution in marine ecosystems is an escalating environmental concern, largely driven by anthropogenic activities, and poses potential threats to ecological health and human well-being. This study embarked on a comprehensive investigation into the concentrations of heavy metals in sediment samples and evaluated their potential ecological and health risks with a focus on Eastern St. Martin’s Island (SMI), Bangladesh. Sediment samples were meticulously collected from 12 distinct sites around the island, and the concentrations of heavy metals, including Mn, Fe, Ni, Zn, Cr, Pb, and Cu, were quantified utilizing atomic absorption spectrometry (AAS). The results revealed that the average concentrations of the metals, in descending order, were Mn (269.5 ± 33.0 mg/kg), Fe (143.8 ± 21.7 mg/kg), Ni (29.6 ± 44.0 mg/kg), Zn (27.2 ± 4.34 mg/kg), Cr (8.09 ± 1.67 mg/kg), Pb (5.88 ± 0.45 mg/kg), and Cu (3.76 ± 0.60 mg/kg). Intriguingly, the concentrations of all the measured metals were found to be within permissible limits and comparatively lower than those documented in various national and international contexts. The ecological risk assessment, based on multiple sediment quality indices such as the geoaccumulation index, contamination factor, and pollution load index, indicated a moderate risk to the aquatic ecosystem but no significant adverse impact on sediment quality. Additionally, the human health risk assessment, encompassing non-carcinogenic hazard indices for different age groups, was considerably below the threshold, signifying no immediate health risk. The total carcinogenic risk was also found to be below acceptable levels. These findings underscore the current state of heavy metal pollution in Eastern St. Martin’s Island, providing valuable insights for environmental monitoring and management. While the immediate risks were not alarming, the study highlights the imperative need for sustained monitoring and the implementation of rigorous regulations to curb heavy metal pollution in order to safeguard both ecological and human health. This warrants the development of policies that are both adaptive and preemptive to ensure the sustainable utilization and conservation of marine resources. Full article

Submerged macrophyes have been widely used to restore aquaculture ponds in recent years. Yet, whether the residual antibiotics in ponds will affect the remediation effect of submerged macrophyes, and the effect of different submerged macrophyes on the water and sediment in aquaculture ponds with antibiotic residues, is unclear. A microcosm experiment was carried out to study the interaction between three kinds of submerged macrophytes and their growing environment with antibiotic residues. Ceratophyllum demersum L. with no roots, Vallisneria spiralis L. with flourish roots, and Hydrilla verticillata L with little roots were chosen to be planted in the sediment added with enrofloxacin (ENR). The growth of submerged macrophytes, the changes of the overlying water and sediment characteristics, and the microbial community in the sediment were analyzed. The results showed that according to the growth rate and nutrients accumulation ability, V. spiralis with flourish roots performed best among the three submerged macrophytes. The concentrations of TOC, TP, NH₄⁺-N, and TN in the overlying water were 25.0%, 71.7%, 38.1%, and 24.8% lower in the V. spiralis treatment comparing with the control, respectively. The richness and diversity of the microorganisms in the sediment of V. spiralis treatment were significantly higher than those in the control, but this advantage was not obvious in the H. verticillata treatment. V. spiralis promoted the growth of Proteobacteria (22.8%) and inhibited the growth of Acidobacteria (32.1%) and Chloflexi (31.7%) in the rhizosphere sediment with ENR residue. The effects of the three submerged macrophytes on the removal of ENR from sediment were not reflected due to the limitation of water depth. Compared with C. demersum and H. verticillata, V. spiralis was more suitable for the remediation of the aquaculture ponds with ENR residue. Full article

As the largest irrigation area in northwest China, the middle and lower reaches of the Yarkant River basin are limited in economic development by the shortage of surface water resources and the increasing demand for groundwater resources from agriculture and industry, and the phenomenon of over-exploitation is becoming increasingly serious, which is not in line with the concept of sustainable development. Therefore, improving the efficiency of water resource utilization while curbing the trend of declining groundwater levels is an important issue that needs to be addressed in the middle and lower reaches of Yarkant at present, specifically, by establishing a distributed hydrological model MIKE SHE based on a soil texture dataset. The model efficiency coefficient Ens, the water balance coefficient (WB), the correlation coefficient r, and the relative error Re were selected to evaluate the model’s applicability. The results were: Ens = 0.84, WB = 0.80, and r = 0.96 for the annual scale runoff simulation and Ens = 0.85, RE = 0.61, and r = 0.96 for the monthly scale runoff simulation. The relative errors between the simulated and observed values of the typical observation wells were 3.45%, 1.59%, 2.52%, and 0.35%. According to the analysis of the soil parameters on the runoff sensitivity and groundwater table sensitivity, the saturated hydraulic conductivity had the greatest effect on the peak discharge. The results show that the MIKE SHE model has some applicability in the lower and middle reaches of the Yarkant River basin. Full article

A very noticeable increase in the beaver population (mainly the Eurasian beaver (Castor fiber L.)) in the East European Plain since the end of the 20th century through reintroduction contributed to the emergence of a large number of beaver dams and ponds, which resulted in the transformation of the channels and the hydrological regime of small rivers. In this paper, for the first time in the Middle Volga region, regularities in the distribution of beaver dams and ponds on small rivers were revealed based on a topographic survey of the river channel, regulated by beaver activity in recent decades. The materials of the paper were obtained during field (geodetic) work in August and September of 2022 in the valleys of two small rivers typical for the north of the Volga Upland, Morkváshinka River (16.6 km) and Morkváshka River (7.8 km), with subsequent statistical processing. According to the results obtained, all the dams we encountered were located in the sections of their channels with relatively small (up to 1%) and medium (1–3%) average gradients. In the upper reaches of the rivers, the expansion of beaver activity is limited to the large gradients of their channels. Along the entire length, there is an alternation of sectors with a “natural” (not regulated by beavers) channel and a cascade of beaver ponds. Drained (at the time of the survey) sectors without dams, as well as those with preserved and destroyed dams, were also identified on the Morkváshinka River. On the whole, 26–48% of the length of the studied rivers has been transformed by beaver activity. The average number of dams per kilometer of the watercourse is 3.7–5.1. The most favorable channel gradients for beaver activity are 3.6–16.6 m/km, or 0.36–1.66%. The average gradient of the channel, above which no beaver dams and related ponds were found in these rivers, is 30 m/km, or 3%. An increase in the channel gradient upstream of the rivers is reflected in the size of beaver dams and ponds. The beaver dams and ponds are slightly larger in the sections of the rivers with a relatively small average gradient than in the sections with a medium average gradient of the channel. Full article

Frequency analysis has long been an important theme of hydrology research. Although meteorological techniques (physical approaches) such as radar nowcasting, remote sensing, and forecasting heavy rainfall events using meteorological simulation models are quite effective for urban disaster prevention, statistical and stochastic theories that include frequency analysis, which are usually used in flood control plans, are also valuable for flood control plans for disaster prevention. Master plans for flood control projects in urban areas often use the concept of T-year hydrological values with a T-year return period. A flood control target is a “landside area that is safe against heavy rainfall or floods with a return period of T years”. This review emphasizes discussions of parameter estimation of stochastic models and selection of optimal statistical models, which include evaluation of goodness-of-fit techniques of statistical models. Based on those results, the authors criticize Japanese standard procedures recommended by the central government. Consistency between parameter estimation and evaluation of goodness-of-fit is necessary. From this perspective, we recommend using the maximum likelihood method and AIC, both of which are related to Kullback–Leibler divergence. If one prefers using SLSC, we recommend not SLSC itself but SLSC’s non-exceedance probability. One important purpose of this review is the introduction of well-used Japanese methods. Because some techniques that are slightly different from the international standard have been used for many years in Japan, we introduce those in the review article. Full article

We investigated the spatio-temporal variations in three key biomolecular compounds (carbohydrates, proteins, and lipids) in particulate organic matter (POM) in the Yellow Sea (YS), South Sea of Korea (SS), East China Sea (ECS), and East Sea (Sea of Japan; ES) in order to estimate the regional annual calorie production rates based on the seasonal data obtained in each region. Carbohydrates were found to be most dominant, followed by lipids across all seas. The euphotic-integral calorie contents of POM during the study period were determined as 53.5 ± 12.6 Kcal m⁻² in the YS; 54.2 ± 7.5 Kcal m⁻² in the SS; 35.7 ± 9.2 Kcal m⁻² in the ECS; and 58.7 ± 6.2 Kcal m⁻² in the ES. Utilizing seasonal carbon conversion factors and primary production rates, we estimated the annual calorie productions, which were highest in the ES (1705 Kcal m⁻² y⁻¹) and lowest in the ECS (403 Kcal m⁻² y⁻¹). This can be attributed to the significantly higher energy efficiency of phytoplankton and faster turnover rate of calorie content. However, caution must be taken when comparing these estimates regionally, considering potential variations in developmental phases among the four regions during the sampling period in 2018. The calorie production rates in this study provide valuable insights into the physiological condition of phytoplankton within specific regions. Full article

Irrigation water quality is important to sustain agricultural productivity. The primary irrigation water sources in Al-Ahsa Oasis, KSA, are groundwater wells, mixed with treated wastewater and agricultural drainage. This study sought to evaluate irrigation water quality in Al-Ahsa Oasis with the aid of using irrigation water quality indices (IWQIs). One hundred and forty-eight different water samples were collected from various irrigation water resources throughout Al-Ahsa Oasis. The investigated physiochemical characteristics include pH, temperature, TDS, EC, turbidity, free chlorine, total hardness, cations (Na, K, Ca, Mg), anions (Cl, CO₃, HCO₃, SO₄), organic matter indices (DO, BOD, COD), and nutrients (NH₄, NO₃, PO₄). The IWQIs used in this study include salinity hazard, sodium adsorption ratio (SAR), Kelly’s ratio (KR), soluble sodium percentage (SSP), Permeability index (PI), residual sodium carbonate (RSC), and magnesium hazard (MH). The results indicated that treated wastewater mixed with groundwater is acceptable for irrigation. Spatial variations in irrigation water quality throughout Al-Ahsa are associated with water resources. For instance, groundwater mixed with agricultural drainage has the highest values of TDS, cations, and anions, whereas the lowest values were reported for treated wastewater, reflecting the good efficiency of wastewater treatment plants. The IWQI results revealed that 4.1% and 62.1% of the investigated irrigation water samples were considered good (class III) and satisfactory (class IV) for irrigation, respectively, whereas 33.8% of the collected water samples fall within the severe irrigation restrictions. Moreover, 79.7% of the investigated water samples were classified to have high to very high salinity hazards (C3, C4) and medium to high sodium hazards (S2, S3). Regular monitoring and assessment of treated water quality and wastewater treatment plant efficiency are important factors in achieving the sustainability of treated wastewater reuse in irrigation and consequently food security. Full article

The giant freshwater whipray is a large-bodied stingray species that is listed as endangered across its known range from India through Southeast Asia. However, little is known about the species’ ecology, biology, and conservation status. We reviewed all available literature, articles, and reports on the species found through database and internet searches in order to consolidate and update information on the giant freshwater whipray. We found that remarkably little research has been done, and most existing information on the species is derived from fisher catch reports. Whiprays of 300 kg or more have been reported in most countries where it occurs. The available evidence suggests that this species is endangered across its range by numerous threats, including fishing, bycatch, bottom trawls, pollution, and habitat destruction and fragmentation. Various reports indicate declines in population size, genetic diversity, and body size. Relatively stable populations may persist in the Maeklong River, Thailand, the Mekong River in Cambodia, and insular Southeast Asia. More work is needed to understand the species’ spatio-temporal distribution, reproductive behavior, migration patterns, and general ecological and biological characteristics in order to inform effective management and conservation plans. Due to difficulties in sampling this rare species and monitoring fisher catches, partnership and collaboration with all stakeholders, including local fishers, government officials, and researchers, is essential to produce conservation gains for the giant freshwater whipray. Full article

The production of olive oil in Portugal and other countries of the Mediterranean region has greatly increased in recent years. Intensification efforts have focused on the growth of the planted area, but also on the increase of the orchards density and the implementation of irrigation systems. Concerns about possible negative impacts of modern olive orchard production have arisen in the last years, questioning the trade-offs between the production benefits and the environmental costs. Therefore, it is of great importance to review the research progress made regarding agronomic options that preserve ecosystem services in high-density irrigated olive orchards. In this literature review, a keywords-based search of academic databases was performed using, as primary keywords, irrigated olive orchards, high density/intensive/hedgerow olive orchards/groves, irrigation strategies, and soil management. Aside from 42 general databases, disseminated research, and concept-framing publications, 112 specific studies were retrieved. The olive orchards were classified as either traditional (TD) (50–200 trees ha⁻¹), medium-density (MD) (201–400 trees ha⁻¹), high-density (HD) (401–1500 trees ha⁻¹), or super-high-density (SHD) orchards (1501–2500 trees ha⁻¹). For olive crops, the ETc ranged from 0.65 to 0.70, and could fall as low as 0.45 in the summer without a significant decrease in oil productivity. Several studies have reported that intermediate irrigation levels linked with the adoption of deficit irrigation strategies, like regulated deficit irrigation (RDI) or partial rootzone drying (PRD), can be effective options. With irrigation, it is possible to implement agroecosystems with cover crops, non-tillage, and recycling of pruning residues. These practices reduce the soil erosion and nutrient leaching and improve the soil organic carbon by 2 to 3 t C ha⁻¹ year⁻¹. In this situation, in general, the biodiversity of plants and animals also increases. We expect that this work will provide a reference for research works and resource planning focused on the improvement of the productive and environmental performance of dense irrigated olive orchards, thereby contributing to the overall enhancement of the sustainability of these expanding agroecosystems. Full article

River runoff predictions in ungauged basins are one of the major challenges in hydrology. In the past, the approach using a physical-based conceptual model was the main approach, but recently, a solution using a data-driven model has been evaluated as more appropriate through several studies. In this study, a new data-driven approach combining various recurrent neural networks and decision tree-based algorithms is proposed. An advantage of recurrent neural networks is that they can learn long-term dependencies between inputs and outputs provided to the network. Decision tree-based algorithms, combined with recurrent neural networks, serve to reflect topographical information treated as constants and can identify the importance of input features. We tested the proposed approach using data from 25 watersheds publicly available on the Korean government’s website. The potential of the proposed approach as a regional hydrologic model is evaluated in the view that one regional model predicts river runoff in various watersheds using the leave-one-out cross-validation regionalization setup. Full article

This study investigated the efficiency of LENFLOC^™ production using a microwave-assisted continuous-flow grafting process. The study discussed the contribution of plant-based coagulants for water and wastewater treatment toward the circular economy in water treatment. Lentil waste extract was used to produce LENFLOC^™ using (2-methacryloyloxyethyl) trimethyl ammonium chloride with 75 wt.% on H₂O as a chain monomer and cerium ammonium nitrate (≥98%) as an initiator. The continuous flow grafting process was conducted at a constant flowrate of 60 mL/min and reaction time of 30 s. The process was optimised using RSM to obtain optimum conditions of process factors. Characterisation studies were conducted using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray. A comparison study was performed using a Jar test with LENFLOC^™, lentil waste extract, and a polymer as coagulants. The results obtained show that the continuous-flow grafting process was efficient with an optimum grafting percentage of 330%. The characterisation studies confirmed the grafting process. A 99% turbidity removal rate was achieved with LENFLOC^™ as a coagulant with a lower dosage compared to the lentil waste extract. Furthermore, microscope imaging showed improved floc compaction when using LENFLOC^™ as a coagulant. The continuous-flow grafting process has been shown to be effective; therefore, its potential for upscaling the process is possible. Full article

Global climate change is anticipated to have a profound impact on drought occurrences, leading to detrimental consequences for the environment, socioeconomic relations, and ecosystem services. In order to evaluate the extent of drought impact, a comprehensive study was conducted in the Hyderabad–Karnataka region, India. Precipitation data from 31 stations spanning a 50-year period (1967–2017) were analyzed using the standardized precipitation index (SPI) based on gamma distribution. The findings reveal that approximately 15% of the assessed years of experienced drought conditions, with a range of influence between 41% and 76% under SPI_3, and between 43% and 72% under SPI_6. Examining the timescale magnitude frequency provided insights into variations in the severity of drought events across different locations and timescales. Notably, the Ballari (−8.77), Chitapur (−8.22), and Aland (−7.40) regions exhibited the most significant magnitudes of drought events for SPI_3 with a 5-year return period. The heightened risk of recurrent droughts in the study area emphasizes the necessity of integrating SPI in decision-making processes, as such integration can markedly contribute to the development of reliable and sustainable long-term water management strategies at regional and national levels. Full article

Salinity management in estuarine systems is crucial for developing effective water-management strategies to maintain compliance and understand the impact of salt intrusion on water quality and availability. Understanding the temporal and spatial variations of salinity is a keystone of salinity-management practices. Process-based numerical models have been traditionally used to estimate the variations in salinity in estuarine environments. Advances in data-driven models (e.g., deep learning models) make them effective and efficient alternatives to process-based models. However, a discernible research gap exists in applying these advanced techniques to salinity modeling. The current study seeks to address this gap by exploring the innovative use of deep learning with data augmentation and transfer learning in salinity modeling, exemplified at 23 key salinity locations in the Sacramento–San Joaquin Delta which is the hub of the water-supply system of California. Historical, simulated (via a hydrodynamics and water quality model), and perturbed (to create a range of hydroclimatic and operational scenarios for data-augmentation purposes) flow, and salinity data are used to train a baseline multi-layer perceptron (MLP) and a deep learning Residual Long-Short-Term Memory (Res-LSTM) network. Four other deep learning models including LSTM, Residual Network (ResNet), Gated Recurrent Unit (GRU), and Residual GRU (Res-GRU) are also examined. Results indicate that models pre-trained using augmented data demonstrate improved performance over models trained from scratch using only historical data (e.g., median Nash–Sutcliffe efficiency increased from around 0.5 to above 0.9). Moreover, the five deep learning models further boost the salinity estimation performance in comparison with the baseline MLP model, though the performance of the latter is acceptable. The models trained using augmented data are then (a) used to develop a web-based Salinity Dashboard (Dashboard) tool that allows the users (including those with no machine learning background) to quickly screen multiple management scenarios by altering inputs and visualizing the resulting salinity simulations interactively, and (b) transferred and adapted to estimate observed salinity. The study shows that transfer learning results more accurately replicate the observations compared to their counterparts from models trained from scratch without knowledge learned and transferred from augmented data (e.g., median Nash–Sutcliffe efficiency increased from around 0.4 to above 0.9). Overall, the study illustrates that deep learning models, particularly when pre-trained using augmented data, are promising supplements to existing process-based models in estuarine salinity modeling, while the Dashboard enables user engagement with those pre-trained models to inform decision-making efficiently and effectively. Full article

Despite studies focusing on soil substrates (carbon and nitrogen) and heavy metal availability, the impact of diversified parent materials in arid alkaline regions has received little attention. To reveal the influence of parent material, we investigated four different parent materials: fluvio-marine, Nile alluvial, lacustrine, and aeolian deposits. We assessed the effect of soil parent materials through selected soil physical and chemical properties, such as clay content, bulk density, pH, and available phosphorus (AP). The Tukey HSD test (SPSS ver. 23) was used to assess the soils derived from these different sediments. Using the R “glmulti” package, we examined this effect in a model of mixed-effects meta-regression. The sum of Akaike weights for models that contained each element was used to estimate the importance of each factor. The average contents of soil organic carbon (SOC) and total N in alluvial deposits were greater (p < 0.001) than those of marine, aeolian, and lacustrine deposits. A multivariate analysis in arid regions revealed that parent material, soil pH, and the availability of P had the greatest effects on SOC concentration, whereas clay content, available P, soil pH, parent material, and bulk density had the greatest effects on soil total nitrogen. The average content of Fe in the aeolian deposits was greater (p < 0.001) than those of marine, alluvial, and lacustrine deposits, without any significant differences between the latter two deposits. We found that the highest average contents of zinc (Zn), manganese (Mn), and copper (Cu) were recorded in alluvial deposits, with significant differences between other deposits. Soil parent material was the major factor impacting soil iron (Fe) content, along with clay content and soil pH. However, soil bulk density was the most important factor controlling soil Zn and Mn contents, while SOC drove Cu content. This study will help in developing a more accurate model of the dynamics of soil substrates and availability of heavy metals by considering readily available variables, such as parent materials, soil pH, soil bulk density, and clay content. Full article

The contamination of water with organic pollutants, such as dyes, has become a serious threat to the environment. Therefore, the development of a cost-effective, eco-friendly, proficient, and visible-light-driven catalyst for the treatment of organic dye-contaminated wastewater has been a burning issue recently. Photocatalysis is suggested as a potential treatment technique for the eradication of organic pollutants. The 1D tunnel-structured manganese oxide octahedral molecular sieve (OMS) is a suitable substance to be tested as a visible-light-driven photocatalyst for the degradation of organic contaminants. However, the fast recombination of photoinduced charges (h⁺/e⁻) limits its photocatalytic application. The development of heterojunctions between OMS and other metals, such as Ag, is a suitable technique for improving the photocatalytic performance of OMS. In this study, Ag-OMS with plasmon-enhanced photocatalytic activity is reported for the photodegradation of crystal violet dye. Manganese oxide OMS was prepared by an acidic precipitation method using potassium permanganate, manganese acetate, and nitric acid as precursor materials. Ag nanoparticles were deposited on OMS using leaf extracts of Calotropis gigantea. The deposition of Ag enhanced the photocatalytic performance of OMS from 68 to 95%. The effects of Ag contents, catalyst dosage, and concentration of crystal violet dye on catalytic performance were explored as well. Approximately 100, 95, and 75% photodegradation of 50, 100, and 150 mg/L crystal violet dye was observed in 90, 120, and 120 min in the presence of 10% Ag-OMS, respectively. Excellent photocatalytic performance, low dose utilization, and reusability proved that Ag-OMS might have practical environmental applications. Full article

Nature-based, low technology wastewater treatment systems can benefit small and remote communities. Adding a constructed floating wetland (CFW) to waste stabilization ponds can enhance treatment efficacy at low cost, depending on appropriate macrophytes. In cold climates, harsh growing conditions may limit CFW success, requiring research under-ambient field conditions. Seven native macrophytes were assessed for the growth, biomass production, and root and shoot uptake of potential contaminants of concern from municipal wastewater in a facultative stabilization pond in Alberta, Canada. All macrophytes established. Scirpus microcarpus had high nitrogen and phosphorus in roots and shoots and phytoextraction potential. Metal and trace elements were highest in Glyceria grandis, Beckmannia syzigachne, and Scirpus microcarpus, mostly greater in roots than shoots, indicating phytostabilization. Tissue contaminant concentrations did not always indicate high contaminant accumulation in the CFW. Total uptake per unit area was greatest for Glyceria grandis, although chromium and molybdenum were greatest in Beckmannia syzigachne and Carex aquatilis, respectively. Beckmannia syzigachne and Scirpus microcarpus have potential for phytoremediation if biomass per unit area is increased. Species variability is high for contaminant accumulation and biomass; in unpredictable climates and wastewaters with suites of contaminants, different macrophytes for wetland water treatment systems are recommended. Full article

Nature-like fish passes are commonly designed as a preferred way to overcome barriers in rivers. However, meeting the recommended hydraulic parameters for these passes can be challenging. As a result, boulders or sills are often incorporated to supplement their structure. From a hydraulic standpoint, the crucial parameters under investigation are the depths and velocities (or the corresponding velocity field). In this study, a comprehensive analysis was conducted on a full-width rock-ramp fish pass constructed in a river, specifically targeting the barbel zone. The achieved parameters were assessed through direct field measurements, complemented by mathematical modeling using 1D and 2D HEC-RAS models (version 6.3.1). For the assessment of model accuracy, the error indices root mean square error (RMSE) and mean absolute error (MAE) were used. Based on their evaluation, the 1D model provides more precise results in the assessed profiles (the RMSE for depths (m) was 0.0663 (for velocities (m∙s⁻¹) 0.293) compared to the 2D model, where the RMSE for depths (m) was 0.070 (for velocities (m∙s⁻¹) 0.398), the MAE for the 1D model for depths (m) was 0.0350 (for velocities (m∙s⁻¹) 0.185) compared to the 2D model, where the MAE for depths (m) was 0.0375 (for velocities (m∙s⁻¹) 0.274)). The findings highlight the differences in the problem-solving approaches between the models as well as the potential for simplifications in practical applications. Full article

The effects of groundwater table fluctuation (GTF) on the remediation of a petrochemically polluted riverside using soil vapor extraction (SVE) were investigated. The migration and transformation of benzene, toluene, ethylbenzene, and o-xylene (BTEX) in cases of natural attenuation, SVE without GTF, and SVE with GTF were simulated using the TMVOC model. The results showed that the optimized extraction well pressure and influencing radius of the target site were 0.90 atm and 8 m, respectively. The removal rates of BTEX in cases of natural attenuation, SVE without GTF, and SVE with GTF were 11.49%, 85.16%, and 97.33%, respectively. The removal rate of BTEX was maximized in the case of SVE with a GTF amplitude of 0.5 m to 1 m. The removal rates of benzene (99.99%), toluene (99.74%), ethylbenzene (96.37%), and o-xylene (94.72%) were maximized in the case of SVE with GTF. For the cases of SVE without GTF and SVE with GTF, mass losses of BTEX in gaseous (0.05 kg, 0.05 kg, respectively) and aqueous phases (5.46 kg, 5.87 kg, respectively) were consistent. However, the mass loss of BTEX in the non-aqueous phase liquid (NAPL) phase in the case of SVE with GTF (155.13 kg) exceeded that in the case of SVE without GTF (135.41 kg). This is because GTF positively affected both the solubility and volatility of BTEX in the NAPL phase. With the groundwater table decreasing, flows of gas and gaseous pollutants increased by 25% along the vertical section. At this stage, the removal rates of volatile organic compounds can be further improved by increasing the flow of the extraction well. Full article

The potable water in residential hydraulic networks is measured using volumetric meters. However, when the water carries air bubbles or pockets through the pipes, the accuracy of the meter readings is reduced, which can negatively impact the billing that users pay for their water consumption. A check valve accessory exists that reduces the size of these air bubbles to correct the meter readings and improve the service experience. However, the device has only been tested for networks with relative pressures higher than 275.79 kPa. This research proposes to characterize the hydraulic behavior of the accessory through an experimental procedure in which the operating conditions are similar to those found in water networks in Latin America, where the networks have relative pressures lower than 275.79 kPa. The study found that the accessory significantly reduces the coefficient of loss for velocities greater than 1 m/s. The use of the device is suggested in flow regimes with Reynolds numbers close to 20,000 for operating conditions of temperatures close to 25 °C and residential pipes with an internal diameter of 20.9 mm and a flow velocity between 1.3 m/s and 1.78 m/s. This condition allows it to operate with minimal local energy loss and a low coefficient of loss, providing an improved service experience. Full article

The quality of water supply systems is still a major problem in developing countries, especially in rural areas. The acute bioluminescence V. fischeri inhibition assay is widely recognized as a toxicological method that can be used to detect the acute effects of different contaminants. In this study, the physicochemical characteristics and toxicology of 72 water samples collected in 18 rural aqueducts located in Boyacá (Colombia) were evaluated. The primary economic activities identified as potential influencers of water quality in the water supply basins were agriculture (n = 3), livestock (n = 2), and domestic sewage discharge (n = 1). The average luminescence inhibition rate was 66%, with a minimum of 29%, and a maximum of 97%. A total of 85% of the tested samples (n = 61) had “moderate acute hazard”, while 15% (n = 15) had “acute hazard”. A total of 95% of the aqueducts distributed water with high risk. There was a weak positive correlation between the apparent color and the V. fischeri inhibition rate (p < 0.05). The water treatments, including disinfection, and the economic activities had no correlation with the inhibition rate of luminescent bacteria. The results of this investigation can be used by sanitary authorities to incorporate future toxicological monitoring of chemical contaminants, such as humic substances and metals, into water-quality monitoring in rural areas. Full article

A buffer zone can be used to analyze the influence of the lake on the surrounding spatial elements, which is of great significance for discussing the problems of lake retreat, vegetation degradation, and overall environmental deterioration in the Aral Sea. Taking the 3 km buffer zone of the Aral Sea as the research area, the spatiotemporal variation characteristics and main influencing factors of the Normalized Difference Vegetation Index (NDVI) in the Aral Sea research area were studied using remote sensing over 31 years (1987, 1997, 1992, 2007, 2010, 2014, 2015, 2017, and 2018). The results showed that the vegetation growth in the Aral Sea buffer zone deteriorates with the retreat of the lake; the vegetation of the small Aral Sea began to recover due to the stable water volume and salt content of the lake; vegetation began to grow in the west coast of the West Aral Sea; the shrinkage of the Aral Sea caused by human activities is an important factor affecting the growth of the vegetation. This study provides a reference for the restoration and reconstruction of regional vegetation. Full article

This paper proposes a feedback, rolling and adaptive operation decision-making mechanism for coupling and nesting of time scales. It is aimed at the change of time scale and the dynamics in the operation process, considering the relationship between operation period and multi-time scales. The key point is to integrate forecasting and operation in order to adapt to the multi-time scales dynamic change in the operation process. The operation process is divided into different time scales; forecasting and operation model method libraries are constructed, and the progressive updating and nesting mechanism are used to realize the process dynamic operation, according to the regulation period or operation period of the reservoir. Taking the Miyun Reservoir in Beijing, China as the research object, the operation mechanism is integrated into the operation process, and the complex forecasting operation and control mechanism are integrated, based on the integrated platform and using modern information technology. The forecasting and operation method uses classic different models, which can be selected based on different goals. The forecasting inflow is used as input, and the output is the water distribution plan, more importantly, the mechanism in the operation process is the key point. This is a rolling modification of the inflow process in the next stage, and the operation plan also changes accordingly. The feasibility, effectiveness, rationality and flexibility of the reservoir dynamic and adaptive operation are verified, so that the reservoir operation is dynamically changing and adapting to the changing demand. The proposed operation mechanism has scientific value and guiding significance to improve the reservoir operation theory, and it provides decision support for the actual reservoir operation and operation business. Full article