ALBERT

Description: In recent years, precipitation patterns in Korea have shifted to be characterized as short and intense rainfalls. In consideration of shallow landslide initiations primarily governed by heavy rainfalls at short-time scales that diminish drainage effects, the concept of critical continuous rainfall is proposed as a single-rainfall-variable threshold for shallow landslide forecasting. To generate a critical continuous rainfall map for hillslope areas in a city of Korea (Busan), this study designed and applied a systematic modeling process. As a preparatory stage, input datasets of geo-hydraulic properties and geotechnical properties were assembled using estimation techniques based on experiment data of field samples. The inherent and fixed critical continuous rainfall values for hillslope areas in Busan were derived through one-dimensional infiltration analysis coupled with infinite slope stability calculations. As a result of a detailed analysis of historical rainfall records in a case study area over a period of 11 years, three false forecasting cases were recorded, whereas all landslide-triggering rainfall events were correctly captured with no missed forecasting cases. The results of the case study indicate that the proposed critical continuous rainfall may be useful as an effective and straightforward indicator for forecasting the initiation of shallow landslides.

Description: Desalination for sustaining agricultural production is conceived as an alternative water source in some Mediterranean countries faced with climatological and hydrological constraints. Although high costs are often cited as limiting factors, how farmers discern desalinated water has not been discussed in-depth in the literature. This paper aims to deepen how desalination is perceived by irrigators, what driving factors are affecting irrigation communities’ decision-making processes, and what learnings can be drawn from their experiences regarding desalination acceptance or rejection. Eleven irrigation communities have been selected from Alicante and Murcia regions (South-East Spain), which account for more than 60,000 irrigators and 120,000 ha. Questionnaires were conducted between March and December 2019. Results highlighted the main advantages (water availability and supply security) and disadvantages (high price affecting profitable crop options, high-energy consumption, water quality standards, the production capacity of desalination plants, no seasonal variation in water production, and shortages due to technical problems) of using desalinated water. Additionally, through the analysis of regional and national press news, it can be concluded that socio-political aspects, such as corruption, cost overruns, and political disputes are also considered.

Description: The change of the Earth’s climate and the increasing human action (e.g., increasing impervious areas) are influencing the recurrence and magnitude of flooding events and consequently the exposure of urban and rural communities. Under these conditions, flood hazard analysis needs to account for this change through the adoption of nonstationary approaches. Such methods, showing how flood hazard evolves over time, are able to support a long-term plan of adaptation in hazard changing perspective, reducing expected annual damage in flood prone areas. On this basis, in this paper a reevaluation of flood hazard in the Benevento province of southern Italy, is presented, providing a reduced complexity methodological framework for near future flood hazard prediction under nonstationary conditions. The proposed procedure uses multiple nonstationary probability models and a LiDAR-derived high-resolution inundation model to provide present and future flood scenarios in the form of hazard maps. Such maps are derived using a spatialization routine of stage probability across the inundation model that is able to work at different scales. The analysis indicates that, overall, (i) flood hazard is going to decrease in the next 30 years over the Benevento province and (ii) many areas of the Calore river floodplain are going to be subject to higher return level events. Consequently, many areas would require new guidelines of use as the hazard level decreases. Limitations of the analysis are related to the choice of the probability model and the parameter estimation approach. A further limit is that, currently, this method is not able to account for the presence of mitigation measurements. However, result validation indicates a very high accuracy of the proposed procedure with a matching degree, with a recently observed 225-years flood, estimated in 98%. On this basis, the proposed framework can be considered a very important approach in flood hazard estimation able to predict near future evolution of flood hazard as modulated by the ongoing climate change.

Description: The goal of this study was to conduct long-term temporal trends analysis of bifenthrin sediment concentrations for measurements conducted from 2001 to 2019 in California waterbodies. Long-term data sites defined as spanning 6 years were available for 143 sites but 17 of these sites were excluded from long analysis because all measurements were below the level of detection. At least one site used in the trends analysis was located in all nine California Water Board Regions thus providing a representative statewide spatial scale. Twenty of the 126 long-term California sediment sites showed a statistically significant downward trend in bifenthrin concentrations while nine sites showed a statistically significant upward trend. Declining bifenthrin sediment concentrations were most evident in urban waterbodies when compared with agricultural dominated waterbodies. An analysis of bifenthrin long-term sediment trends by waterbody with at least three sites showed a significant trend for only one residential/urban stream and this trend was declining. In summary, the trends analysis of bifenthrin sediment concentrations does show a compelling case for declining concentrations in the State of California during an 18-year time period that includes a time period before and after the urban use of bifenthrin was further regulated.

Description: Precipitation obtained from rain gauges is an essential input for hydrological modelling. It is often sparse in highly topographically varying terrain, exhibiting a certain amount of uncertainty in hydrological modelling. Hence, satellite rainfall estimates have been used as an alternative or as a supplement to station observations. In this study, an attempt was made to evaluate the Tropical Rainfall Measuring Mission (TRMM) and Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), employing a semi-distributed hydrological model, i.e., Soil and Water Assessment Tool (SWAT), for simulating streamflow and validating them against the flows generated by the India Meteorological Department (IMD) rainfall dataset in the Gurupura river catchment of India. Distinct testing scenarios for simulating streamflow were made to check the suitability of these satellite precipitation data. The TRMM was able to better estimate rainfall than CHIRPS after performing categorical and continuous statistical results with respect to IMD rainfall data. While comparing the performance of model simulations, the IMD rainfall-driven streamflow emerged as the best followed by the TRMM, CHIRPS-0.05, and CHIRPS-0.25. The coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), and percent bias (PBIAS) were in the range 0.63 to 0.86, 0.62 to 0.86, and −14.98 to 0.87, respectively. Further, an attempt was made to examine the spatial distribution of key hydrological signature, i.e., flow duration curve (FDC) in the 30–95 percentile range of non-exceedance probability. It was observed that TRMM underestimated the flow for agricultural water availability corresponding to 30 percent, even though it showed a good performance compared to the other satellite rainfall-driven model outputs.

Description: Water has a crucial effect on the time-dependent behavior of rocks. The long-term cyclical fluctuations of reservoir water level lead to dry–wet (DW) cycles of rocks on reservoir bank slopes, making this influential factor more complex. To deeply understand the time-dependent behavior of rocks under DW cycles, argillite from the reservoir bank slope of Longtan Hydropower Station was used to perform a series of triaxial creep tests. Subsequently, based on analysis of creep test results after different DW cycles, a damage nonlinear Burgers viscoelastic-plastic (DNBVP) model considering the effect of saturation–dehydration cycles was proposed by introducing a nonlinear viscoplastic body and a damage variable describing DW cycles. Then, the three-dimensional creep equations of the new model were derived and its creep parameters were identified. Comparison between the theoretical curves and the test results shows that the theoretical curves of the DNBVP model were able to describe rock creep tests results after different DW cycles. Furthermore, by comparing classical creep models with the proposed model, it was found that the DNBVP model can accurately reflect the nonlinear characteristics of rocks at the accelerated creep stage. Finally, the sensitivity of the DNBVP model was analyzed and discussed, and three-dimensional central difference expressions necessary for secondary development of the new model were also derived in detail. The proposed new model with secondary development may provide a basis for improving the geotechnical design of reservoir bank slopes and the control of reservoir bank landslides.

Description: Non-structural measures for flood risk mitigation are often more economically accessible, easier to implement, and are highly effective, especially in view of the pursuit of risk resilience objectives. Among the non-structural measures, more importance is increasingly being attributed to flood proofing interventions. There are two main types of flood proofing: dry proofing and wet proofing. An example of dry proofing is shielding, which involves the use of flood barriers that can be installed in the entrances of buildings or outside the buildings in order to avoid contact with the houses and deviate the water flow. Their use must be supported by a detailed hydraulic analysis to ensure the correct design is used. This kind of intervention also avoids inducing a feeling of false security (the levee effect) in the exposed population, and therefore contributes to increasing their resilience. The aim of the work presented here is to determine an optimal combination of and choice between different types of structural and non-structural measures through the development of a methodology for assessing the real efficiency levels of different measures, using a cost–benefit analysis (CBA) and starting from the estimation of the direct flood damage. The application of the CBA to a case study of the Mela river in northeastern Sicily, which suffered a flooding event in October 2015, is supported by the determination of the real damages after the flood and the modeling of the same damages for alternative scenarios. The results affirm the possibility of reducing or avoiding some of the damage using the proposed flood proofing measures instead of classical ones.

Description: Water resources are under growing pressures globally, and better basin planning is crucial to alleviate current and future water scarcity issues. Communicating the complex interconnections and needs of natural and human systems is a significant research challenge. With advances in cyberinfrastructure allowing for new innovative approaches to basin planning, this same technology can also facilitate better stakeholder engagement. The potential benefits of using digital basin planning platforms for stakeholder engagement are immense; yet, there is limited guidance on how to best use these platforms for more effective stakeholder engagement in water-related issues and projects. We detail our digital platform, Basin Futures, and highlight the potential uses for stakeholder engagement through an integrative framework across different assessment levels. Basin Futures is a web application that is an entry-level modelling tool that aims to support rapid and exploratory basin planning globally. As a cloud-based tool, it brings together high-performance computing and large-scale global datasets to make data analysis accessible and efficient. We explore the potential use of the tool through three case studies exploring agricultural development, transboundary water-sharing agreements and allocating water for environmental flows.

Description: The Valdivia River estuary (VRE) located in south-central Chile is known as one of the largest estuarine ecosystems on the Pacific coast. This research aims to determine the intra-tidal and sub-tidal variability of saline intrusions into the VRE between November 2017 and March 2019 derived from salinity sensors located along the VRE. Complementary hydrographic measurements were conducted during flood and ebb conditions of the spring and neap tides for each of the four seasons of the year along the central axis of the VRE. The results of the salinity time series showed that saline intrusions (values greater than 0.5 Practical Salinity Units) occurred ~20 km from the estuary mouth, when the total flow of the Cruces and Calle-Calle rivers (main tributaries of the estuary) was low, around 280–300 m3 s−1. During the same period, the best co-variability was observed between the saline intrusions and the mixed-semidiurnal tide and the fortnightly and monthly periods of the tide. Regression analyses indicated that salinity intrusion length (L) is best correlated to discharge (D) with a fractional power model L α D−1/2.64 (R2 = 0.88). The decreasing discharge trend, found between 2008–2019, implies that saline water intrusions would negatively impact the Valdivia’s main drinking water intake during the low rainfall season under future climate conditions.

Description: Climate change has resulted in increased intensity and frequency of typhoons and storm surges. Accordingly, attention has been paid to securing the breakwater’s stability to protect the safety of the port. Herein, hydraulic model experiments were conducted to evaluate the hydraulic performance of a vertical breakwater having a rear parapet. For comparison, cases in which the parapet was placed on the seaside, the harborside, and at the center of the breakwater were considered. Regular waves were used for convenient performance analysis. Five wave gauges and nine pressure transducers were installed to secure physical data for hydraulic performance evaluation. Results showed that a rear parapet can reduce the maximum wave force acting on the breakwater. Even though impulsive pressure was generated, it did not affect the stability of the breakwater owing to the phase difference between the maximum wave pressures acting on the caisson and parapet. By decreasing the maximum wave force, the required self-weight that satisfies the safety factor of 1.2 was reduced by up to 82.7%; the maximum bearing pressure was reduced by up to 47.6% compared with that of the parapet located on the seaside. Thus, the rear parapet was found to be more suitable for actual applications.

Description: Ice phenomena are construed as the occurrence of ice in water irrespective of its structure, form, and duration. One of the most frequently discussed research problems is the possibility of using long-term ice phenology as an indicator of changes of the thermal conditions of ambient air. The study used correlation analysis and regression models in order to determine changes in the parameters studied over time. In order to compare the ice regime of the study reservoir and other lakes in the region, discriminant function analysis, principal components analysis (PCA), and canonical redundancy analysis (RDA) were applied. During the 52 winter seasons studied (1964–2015), there were weak but still statistically significant trends concerning the increase in air temperature in the region (by 0.3 °C per decade), the reduction in the number of days with ice cover (by 8.6 days per decade) and the decline in the maximum and average thicknesses of lake ice (by 2.0 cm and 1.2 cm per decade). The low average depth and volume capacity are reflected in the rapid freezing rate of the reservoir, and its location results in a longer duration of ice cover, greater ice thickness, and later dates of its melting.

Description: Coastal ecosystems face increasing anthropogenic pressures worldwide and their management requires a solid assessment and understanding of the cumulative impacts from human activities. This study evaluates the spatial variation of benthic macrofaunal communities, sediments, and heavy metals in the sub-Arctic coastal ecosystems around Sept-Îles (Québec, Canada)—a major port area in the Gulf of St. Lawrence. Physical sediment properties varied in the studied area, with a general sandy-silty profile except for specific locations in Baie des Sept Îles where higher organic matter and heavy metal concentrations were detected. Macrofaunal assemblages were evaluated for two taxa size classes (organisms 〉 0.5 mm and 〉 1 mm) and linked to habitat parameters using regression models. Communities of smaller organisms showed signs of perturbation for one assemblage close to industrial activities at Baie des Sept Îles, with an increased number of tolerant and opportunistic species, contrasting to neighboring regions whose compositions were similar to other ecosystems in the Gulf of St. Lawrence. This study enhances the understanding of sub-Arctic benthic communities and will contribute to monitoring programs for industrial harbor ecosystems.

Description: Maintaining the reservoir safety of large dams has considerable importance for the public where they are constructed in heavily populated and industrialized areas. The extreme hydrodynamic force caused by ground acceleration, cavitation damage, and vibration are among concerns that threaten the safety of the spillway and its conveyance structures when subjected to a natural disaster, such as earthquakes and severe floods. Current research investigates the hydrostatic and hydrodynamic performance of the Karkheh Dam spillway radial gate through 3-D finite element (FE) models using ABAQUS/Explicit. The common loads applied on the radial gate were reviewed and stress–strain in the skin plate and trunnion were investigated as a result of developed hydrodynamic pressures. The performance of conveyance structures subjected to significant discharge was also investigated through a small-scale model to evaluate the cavitation damage index. The results of this research will help researchers in the field of civil and hydraulic engineering for the risk analysis of the radial gates and conveyance structures.

Description: As sensor measurements emerge in urban water systems, data-driven unsupervised machine learning algorithms have drawn tremendous interest in event detection and hydraulic water level and flow prediction recently. However, most of them are applied in water distribution systems and few studies consider using unsupervised cluster analysis to group the time-series hydraulic-hydrologic data in stormwater urban drainage systems. To improve the understanding of how cluster analysis contributes to flooding location detection, this study compared the performance of K-means clustering, agglomerative clustering, and spectral clustering in uncovering time-series water depth dissimilarity. In this work, the water depth datasets are simulated by an urban drainage model and then formatted for a clustering problem. Three standard performance evaluation metrics, namely the silhouette coefficient index, Calinski–Harabasz index, and Davies–Bouldin index are employed to assess the clustering performance in flooding detection under various storms. The results show that silhouette coefficient index and Davies–Bouldin index are more suitable for assessing the performance of K-means and agglomerative clustering, while the Calinski–Harabasz index only works for spectral clustering, indicating these clustering algorithms are metric-dependent flooding indicators. The results also reveal that the agglomerative clustering performs better in detecting short-duration events while K-means and spectral clustering behave better in detecting long-duration floods. The findings of these investigations can be employed in urban stormwater flood detection at the specific junction-level sites by using the occurrence of anomalous changes in water level of correlated clusters as flood early warning for the local neighborhoods.

Description: This paper presents a study of two transport timescales (TTS), i.e., the residence time and exposure time, of a hyper-tidal estuary using a widely used numerical model. The numerical model was calibrated against field measured data for various tidal conditions. The model simulated current speeds and directions generally agreed well with the field data. The model was then further developed and applied to study the two transport timescales, namely the exposure time and residence time for the hyper-tidal Severn Estuary. The numerical model predictions showed that the inflow from the River Severn under high flow conditions reduced the residence and exposure times by 1.5 to 3.5% for different tidal ranges and tracer release times. For spring tide conditions, releasing a tracer at high water reduced the residence time and exposure time by 49.0% and 11.9%, respectively, compared to releasing the tracer at low water. For neap tide conditions, releasing at high water reduced the residence time and exposure time by 31.6% and 8.0%, respectively, compared to releasing the tracer at low water level. The return coefficient was found to be vary between 0.75 and 0.88 for the different tidal conditions, which indicates that the returning water effects for different tidal ranges and release times are all relatively high. For all flow and tide conditions, the exposure times were significantly greater than the residence times, which demonstrated that there was a high possibility for water and/or pollutants to re-enter the Severn Estuary after leaving it on an ebb tide. The fractions of water and/or pollutants re-entering the estuary for spring and neap tide conditions were found to be very high, giving 0.75–0.81 for neap tides, and 0.79–0.88 for spring tides. For both the spring and neap tides, the residence and exposure times were lower for high water level release. Spring tide conditions gave significantly lower residence and exposure times. The spatial distribution of exposure and residence times showed that the flow from the River Severn only had a local effect on the upstream part of the estuary, for both the residence and exposure time.

Description: We conducted a study on water management at the Boise River Watershed in a changing global environment potentially induced by climate variability and urbanization. Environmental ‘hotspots’ associated with water quality and quantity were first identified to select suitable management options, such as Low Impact Development (LID is commonly used for urban storm water management to reduce impacts induced by flash flood in urban environment while improving water quality standard by filtering non-point source pollutants from predominant, impervious land segments in urban settings.) and Best Management Practices (BMPs) for urban and rural land segments, respectively. A decision-making process was employed to evaluate the cost-effectiveness for each management option based on multiple criteria, including water quality, financial challenges, and other environmental concerns. The results show that LID/BMPs were useful to control water quality in the watershed. The effectiveness of LID/BMPs implementation was subject to change with the placement location and consideration objectives associated with economic or environmental aspects. It appears that about 10% of the study area is required to implement water management options (LID/BMP) to improve water quality potentially driven by climate variability and urbanization. We anticipate that this study will make a case toward developing a sustainable water management plan in a changing global environment, especially for the urban–rural interface settings.

Description: Oil and gas effluents contains highly toxic and harmful organic pollutants. Therefore, it is necessary to eliminate and/or reduced the concertation of organic pollutants to a technologically acceptable levels before their discharge into water streams. This study investigates the application of nanoscale zero-valent iron (nZVI), and hydrogen peroxide (H2O2) for removal of organic pollutants from real oily produced water. Batch studies were performed and effect of different operating parameters, including concentration of nZVI and H2O2, pH and reaction time were studied. Moreover, optimization of independent variables was performed using central composite design (CCD) in response surface methodology (RSM). The experimental set up provided maximum removal efficiencies of 89.5% and 75.3% for polycyclic aromatic hydrocarbons (PAHs) and chemical oxygen demand (COD), respectively. The optimum values of independent variables such as concentrations of nZVI, and H2O2, contact time and pH were obtained as 4.35 g/L, 1.60 g/L, 199.9 min and 2.9, respectively. Predicted PAHs and COD removal efficiencies at the optimum values of independent variables were found as 89.3% and 75.7%, respectively which are in line with the experimental values. The study indicates that application of heterogeneous Fenton like oxidation system using nZVI as a catalyst is an efficient treatment method for removal of organic pollutants from real produced water.

Description: The CyFFORS (Cyprus Flood Forecasting System) project aims at increasing flood risk awareness and promoting preparedness against flooding by developing and validating a pilot flood forecasting system targeted over three river/stream basins in the Larnaca region, Cyprus, and Attica region, Greece. The present study demonstrates the analysis of flood-associated information, based on ground-based and ERA5 model reanalysis data, which is a necessary procedure prior to the development of the hydrometeorological modeling tool, in one of the study areas, namely in the Rafina catchment in Attica, Greece. The analysis focusses on 12 stream flood episodes that occurred in the period 2008–2014. The results show that most events were associated with a typical, for the study area, wet-season cyclonic activity. The detailed investigation of two case studies highlighted important spatiotemporal differences in the generation and development of rainfall, as well as in the flooding magnitude, which were related to specific characteristics of the synoptic-scale forcing, topography and soil moisture preconditioning. Moreover, highly correlated positive relationships were found between the observed maximum stream discharge and the duration and maximum total accumulation of precipitation. A strong positive correlation was also evident between the peak discharge and the flooding impacts, leading to the identification of preliminary discharge thresholds for impact-based warnings, which can be applied to the pilot CyFFORS forecasting system.

Description: Harmful algae blooms (HAB) in eutrophic lakes and rivers have become serious water quality problems that are difficult to eliminate using common methods. Previous research has demonstrated that powerful ultrasound can somewhat control cyanobacteria in HABs; however, effective and energy-efficient settings for ultrasonic parameters have not yet been rigorously determined. The results of this study showed that the effect of cyanobacteria removal was enhanced with ultrasonic frequencies, densities, and radiation durations of 20–90 kHz, 0.0005–0.1 W/mL and 0.5–10 min, respectively. Our analyses further demonstrated that the effective distance of ultrasound decreased with increasing frequency, and that damaged algae cells were able to repair themselves at low ultrasonic densities. To address the high energy consumption and small effective distance of conventional ultrasonic radiation treatments, we proposed a new cyanobacteria removal method based on two applications of low-frequency, low-density and short-duration ultrasonic radiation. We defined the energy effectiveness factors of ultrasonic radiation for algae removal as the algae removal rate divided by ultrasonic dosage. This method yielded an 87.6% cyanobacteria removal and the highest energy effectiveness factor, suggesting that two cycles of treatment provide a low-energy method for enhancing existing algae-removing technologies used in large bodies of water.

Description: Amphipods are a key component of aquatic ecosystems due to their distribution, abundance and ecological role. They also serve as hosts for many micro- and macro-parasites. The importance of parasites and the necessity to include them in ecological studies has been increasingly recognized in the last two decades by ecologists and conservation biologists. Parasites are able to alter survival, growth, feeding, mobility, mating, fecundity and stressors’ response of their amphipod hosts. In addition to their modulating effects on host population size and dynamics, parasites affect community structure and food webs in different ways: by increasing the susceptibility of amphipods to predation, by quantitatively and qualitatively changing the host diet, and by modifying competitive interactions. Human-induced stressors such as climate change, pollution and species introduction that affect host–parasite equilibrium, may enhance or reduce the infection effects on hosts and ecosystems. The present review illustrates the importance of parasites for ecosystem processes using examples from aquatic environments and amphipods as a host group. As seen from the literature, amphipod–parasite systems are likely a key component of ecological processes, but more quantitative data from natural populations and field evidence are necessary to support the results obtained by experimental research.

Description: Source protection is part of a multi-solution approach for the provision of safe drinking water. In the Republic of Ireland, community-led Group Water Schemes (GWS) provide treated drinking water to approximately 69,000 rural households. Between 2009 and 2019, preliminary source protection assessments were undertaken for 70 GWS abstracting from surface water sources to provide physical catchment characterisation and untreated and treated water quality analysis. Catchment areas upstream of abstraction points varied in size, with 51.5% being less than 5 km2 and only 10.7% being larger than 100 km2. The majority (91%) of assessed GWS serve a population of less than 3000 people, and 94% supply less than 1500 m3 per day. Exceedances of the EU Drinking Water Regulations were recorded for 27 parameters, with the greatest number of exceedances due to total trihalomethanes followed by microbial contamination. The most frequent recommendation for improving GWS drinking water quality was associated with managing livestock access to local water bodies. Improving stakeholder engagement represented 38% of all recommendations made. Drinking water source protection measures and catchment-scale actions can be an additional model to assist in the delivery of Integrated Catchment Management and river basin management planning in the Republic of Ireland. For the GWS sector, challenges lie in securing resources to improve both source water and drinking water quality to deliver integrated catchment management plans for source protection.

Description: Accurate determination of river flows and variations is used for the efficient use of water resources, the planning of construction of water structures, and preventing flood disasters. However, accurate flow prediction is related to a good understanding of the hydrological and meteorological characteristics of the river basin. In this study, flow in the river was estimated using Multi Linear Regression (MLR), Artificial Neural Network (ANN), M5 Decision Tree (M5T), Adaptive Neuro-Fuzzy Inference System (ANFIS), Mamdani-Fuzzy Logic (M-FL) and Simple Membership Functions and Fuzzy Rules Generation Technique (SMRGT) models. The Stilwater River in the Sterling region of the USA was selected as the study area and the data obtained from this region were used. Daily rainfall, river flow, and water temperature data were used as input data in all models. In the paper, the performance of the methods is evaluated based on the statistical approach. The results obtained from the generated models were compared with the recorded values. The correlation coefficient (R), Mean Square Error (MSE), and Mean Absolute Error (MAE) statistics are computed separately for each model. According to the comparison criteria, as a final result, it is considered that Mamdani-Fuzzy Logic (M-FL) and Simple Membership Functions and Fuzzy Rules Generation Technique (SMRGT) model have better performance in river flow estimation than the other models.

Description: This study compared the performance of thermophilic and mesophilic digesters of an anaerobic digestion system from palm oil mill effluent (POME), in which temperature is a key parameter that can greatly affect the performance of anaerobic digestion. The digesters were incubated at two distinct temperatures of 55 and 37 °C, and operated with varying organic loading rates (OLRs) of 2.4, 3.2, and 4.0 g COD/L.d by altering the chemical oxygen demand (COD) of acidified POME during feeding. The results indicated that the performance of anaerobic digestion increased as the OLR increased from 2.4 to 4.0 g COD/L.d. At the OLR of 4.0 g COD/L.d, the thermophilic condition showed the highest methane yield of 0.31 ± 0.01 L/g COD, accompanied by the highest COD removal and volatile solid reduction, which were found to be higher than the mesophilic condition. Microbial community analysis via denaturing gradient gel electrophoresis (DGGE) revealed that Methanothermobacter sp. emerges as the dominant microbe, which is known to utilize the carbon dioxide pathway with hydrogen acting as an electron donor for methane formation

Description: The proper management of a municipal water system is essential to sustain cities and support the water security of societies. Urban water estimating has always been a challenging task for managers of water utilities and policymakers. This paper applies a novel methodology that includes data pre-processing and an Artificial Neural Network (ANN) optimized with the Backtracking Search Algorithm (BSA-ANN) to estimate monthly water demand in relation to previous water consumption. Historical data of monthly water consumption in the Gauteng Province, South Africa, for the period 2007–2016, were selected for the creation and evaluation of the methodology. Data pre-processing techniques played a crucial role in the enhancing of the quality of the data before creating the prediction model. The BSA-ANN model yielded the best result with a root mean square error and a coefficient of efficiency of 0.0099 mega liters and 0.979, respectively. Moreover, it proved more efficient and reliable than the Crow Search Algorithm (CSA-ANN), based on the scale of error. Overall, this paper presents a new application for the hybrid model BSA-ANN that can be successfully used to predict water demand with high accuracy, in a city that heavily suffers from the impact of climate change and population growth.

Description: Evaluating the impact of climate change on water resources is necessary for improving water resource management and adaptation measures at the watershed level. This study evaluates the impact of climate change on streamflow in South Korea using downscaled climate change information based on the global climate model (GCM) and hydrological simulation program–FORTRAN model. Representative concentration pathway (RCP) scenarios 4.5 and 8.5 W/m2 were employed in this study. During the distant future (2071–2099), the flow increased by 15.11% and 24.40% for RCP scenarios 4.5 and 8.5 W/m2, respectively. The flow is highly dependent on precipitation and evapotranspiration. Both precipitation and evapotranspiration increased, but the relative change of precipitation was greater than the relative change of evapotranspiration. For this reason, the flow would show a significant increase. Additionally, for RCP 8.5 W/m2, the variability of the flow according to the GCM also increased because the variability of precipitation increased. Moreover, for RCP 8.5 W/m2, the summer and autumn flow increased significantly, and the winter flow decreased in both scenarios. The variability in autumn and winter was so great that the occurrence of extreme flow could intensify further. These projections indicated the possibility of future flooding and drought in summer and winter. Regionally, the flow was expected to show a significant increase in the southeastern region. The findings presented for South Korea could be used as primary data in establishing national climate change adaptation measures.

Description: Due to their outstanding anti-clogging ability, vortex pumps have been gradually promoted and applied in recent years. However, when transporting sewage containing solids, they will still encounter problems such as partial clogging, overwork wear, etc., therefore, it is particularly important to master the flow characteristics of solid particles in the vortex pump. In this paper, the Discrete Element Model-Computational Fluid Dynamics (DEM-CFD) coupled calculation method is introduced into the numerical simulation of vortex pumps and particles with diameters of 1, 2 and 3 mm and concentrations of 1% and 5%, were subjected to numerical simulation and study of the flow characteristics of the particles, then rapeseed was used to represent solid particles in tests. It was obvious that the CFD results were in good agreement with the experimental results, whereby the high speed photography experimental results of the pump inlet section show that the experimental results are consistent with the numerical simulation results. The results show that there are three typical movement tracks of solid particles in the vortex pump: in Track A particles flow through the impeller and enter the volute by the through flow, in Track B particles go directly into the volute through the lateral cavity under the influence of circulation flow and in Track C the particles enter the impeller from the front cover end area of the impeller blade inlet and then into the volute through the back half area of blade. It can be found that the particles are mainly distributed at the back of the volute.

Description: Groundwater (GW) is the primary source of unfrozen freshwater on the planet and in many semi-arid areas, it is the only source of water available during low-water periods. In north-central Chile, there has been GW depletion as a result of semi-arid conditions and high water demand, which has unleashed major social conflicts, some due to drought and others due to agribusiness practices against the backdrop of a private water management model. The Ligua and Petorca watersheds in the Valparaíso Region were studied in order to analyze the influence of climatic and anthropogenic factors on aquifer depletion using an interdisciplinary approach that integrates hydroclimatic variables, remote sensing data techniques, and GW rights data to promote sustainable GW management. The Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) were calculated and the 2002–2017 land-use change was analyzed. It was shown that GW decreased significantly (in 75% of the wells) and that the hydrological drought was moderate and prolonged (longest drought in the last 36 years). The avocado-growing area in Ligua increased significantly—by 2623 ha—with respect to other agricultural areas (higher GW decrease), while in Petorca, it decreased by 128 ha. In addition, GW-rainfall correlations were low and GW rights were granted continuously despite the drought. The results confirmed that aquifer depletion was mostly influenced by human factors due to overexploitation by agriculture and a lack of water management.

Description: Monitoring of various naturally present substances or physical properties of the water, commonly called environmental tracers, can provide valuable insight in characteristics of groundwater flow systems and intrinsic processes. Analysis of individual tracer data most often gives an ambiguous interpretation, but employment of multiple diverse tracers can greatly increase interpretation reliability. We monitored multiple natural tracers including spring water electrical conductivity, temperature, loads of major anions and cations, stable isotopes of water, and total organic carbon together with discharge dynamics on Krbavica springs located in the Croatian part of Dinaric Karst region. We also monitored dissolved oxygen concentration as an indicator of “excess air” dynamics in the spring water, which is a very rarely recognized and not properly understood phenomenon in the karst groundwater studies. Analysis of the monitoring data revealed main characteristics of the karst system, among which following can be emphasized: (1) oxygen concentration together with conductivity and temperature (parameters monitored with high temporal resolution) were strongly related to discharge dynamics, while seasonal patterns were absent; (2) supersaturation with oxygen confirmed presence of “excess air”, most pronounced in high water conditions following the hydrograph peaks, indicating prevalence of closed flow conditions within the system; (3) electrical conductivity showed “anomalous” gradual decrease during the hydrograph recessions, attributed both to CO2 dynamics and mobilization of water from tiny fissures during high recharge conditions; and (4) stable isotope measurements confirmed good mixing of water within the system with mean residence time of a few years. Simultaneous monitoring of diverse tracer dynamics enabled detailed characterization of the karst system without excessive ambiguity.

Description: Water scarcity is the most constraining factor for crop production, especially in arid and semi-arid areas of Mediterranean countries such as Morocco. Within these conditions, different water-saving strategies using deficit irrigation (DI) were tested on two six-years old clementine varieties (‘Sidi Aissa’ and ‘Orogrande’). These DI strategies were applied during the second part of fruit growth and during fruit maturation and included: the control treatment (Cntl), in which the trees received 100% of crop evapotranspiration (ETc) for the entire irrigation season; regulated deficit irrigation (RDI), with an application of 75% of ETc (RDI-1); partial rootzone drying (PRD), with an alternating irrigation between the two root system halves for 3–4 (PRD-3/4) and 7 (PRD-7) days, with an application of 50% crop water requirements; and RDI-2, with an application of 50% of crop water needs during fruit maturation. The results indicate that the trees preferably absorb the water from the upper 0–30 cm-depth soil profile and that fruit drop was increased by PRD for ‘Sidi Aissa’, whereas RDI-1 had no effect on this parameter. The DI strategies had no effect on fruit drop for ‘Orogrande’. The PRD reduced fruit size, yield and fruit juice content, with the effect being more pronounced on ‘Sidi Aissa’. The RDI-1 had no effect on fruit yield for ‘Orogrande’ but reduced it for ‘Sidi Aissa’. RDI-2 had no effect on yield, fruit size or fruit juice content. The DIs tested increased water use efficiency and enhanced fruit maturation as a result of increased juice sugar content and reduced acidity. The PRD tends to increase salt accumulation in the rootzone. Overall, ‘Orogrande’ was less sensitive to water stress and was more water-use efficient, and, under the semi-arid conditions of the experimental zone, PRD should not be used on clementine.

Description: Hydrological models, with different levels of complexity, have become inherent tools in water resource management. Conceptual models with low input data requirements are preferred for streamflow modeling, particularly in poorly gauged watersheds. However, the inadequacy of model structures in the hydrologic regime of a given watershed can lead to uncertain parameter estimation. Therefore, an understanding of the model parameters’ behavior with respect to the dominant hydrologic responses is of high necessity. In this study, we aim to investigate the parameterization of the HBV (Hydrologiska Byråns Vattenbalansavedelning) conceptual model and its influence on the model response in a semi-arid context. To this end, the capability of the model to simulate the daily streamflow was evaluated. Then, sensitivity and interdependency analyses were carried out to identify the most influential model parameters and emphasize how these parameters interact to fit the observed streamflow under contrasted hydroclimatic conditions. The results show that the HBV model can fairly reproduce the observed daily streamflow in the watershed of interest. However, the reliability of the model simulations varies from one year to another. The sensitivity analysis showed that each of the model parameters has a certain degree of influence on model behavior. The temperature correction factor (ETF) showed the lowest effect on the model response, while the sensitivity to the degree-day factor (DDF) highly depends on the availability of snow cover. Overall, the changes in hydroclimatic conditions were found to be mostly responsible for the annual variability of the optimal parameter values. Additionally, these changes seem to actuate the interdependency between the parameters of the soil moisture and the response routines, particularly Field Capacity (FC), the recession coefficient K0, the percolation coefficient (KPERC), and the upper reservoir threshold (UZL). The latter combines either to shrink the storage capacity of the model’s reservoirs under extremely high peak flows or to enlarge them under overestimated water supply, mainly provoked by abundant snow cover.

Description: To advance to water sensitive cities (WSC) it will be necessary to achieve the commitment of the citizens, involving them in this transition. Citizen participation is considered essential, and one of the possible approaches to achieve this is through Design Thinking (DT), a human-centered methodology that allows creating a framework to develop the hydrosocial contract. The Suez group proposed the challenge of collecting initiatives to achieve more efficient use of urban water in homes, by conducting a pilot in one of its investee companies, Aguas de Huelva. Our research proposal, selected by the Suez group, to achieve greater engagement of households regarding efficient water use, was to develop a web-based prototype applying DT methodologies, which would allow us to generate new messages and meanings regarding water, producing an innovation of meaning that would enable tracking the progress of the results. This article describes the approved framework to carry out the pilot experience in the homes of the city of Huelva in Andalusia, Spain.

Description: Climate change is expected to affect the occurrence of heavy rainfall. We analyzed trends of heavy rainfall days for the last decades in Germany. For all available stations with daily data, days exceeding daily thresholds (10, 20, 30 mm) were counted annually. The Mann–Kendall trend test was applied to overlapping periods of 30 years (1951–2019). This period was extended to 1901 for 111 stations. The stations were aggregated by natural regions to assess regional patterns. Impacts of data inconsistencies on the calculated trends were evaluated with the metadata and recent hourly data. Although the trend variability depended on the chosen exceedance threshold, a general long-term trend for the whole of Germany was consistently not evident. After 1951, stable positive trends occurred in the mountainous south and partly in the northern coastal region, while parts of Central Germany experienced negative trends. The frequent location shifts and the recent change in the time interval for daily rainfall could affect individual trends but were statistically insignificant for regional analyses. A case study supported that heavy rains became more erosive during the last 20 years. The results showed the merit of historical data for a better understanding of recent changes in heavy rainfall.

Description: The socio-hydrology community has been very successful in promoting the need for taking the human factor into account in the mainstream hydrology literature since 2012. However, the interest in studying and modeling human-water systems is not new and pre-existed the post-2012 socio-hydrology. So, it is critical to ask what socio-hydrology has been able to offer that would have been unachievable using the existing methods, tools, and analysis frameworks. Thus far, the socio-hydrology studies show a strong overlap with what has already been in the literature, especially in the water resources systems and coupled human and natural systems (CHANS) areas. Nevertheless, the work in these areas has been generally dismissed by the socio-hydrology literature. This paper overviews some of the general concerns about originality, practicality, and contributions of socio-hydrology. It is argued that while in theory, a common sense about the need for considering humans as an integral component of water resources systems models can strengthen our coupled human-water systems research, the current approaches and trends in socio-hydrology can make this interest area less inclusive and interdisciplinary.

Description: Soil erosion is the main threat to the stability of ecological environment and the harmonious development of society in Shendong Mining Area. The main causes of this threat include the strong interference of natural characteristics and land development. Scientific soil and water conservation measures can coordinate the contradictions among coal economic development, ecological protection, and residents’ prosperity. Based on particle swarm optimization and analytic hierarchy process, the benefit evaluation system of soil and water conservation measures in Shendong Mining Area is established. The weight ratio of three kinds of benefits in Shendong coal mine collapse area is: ecological benefit 〉 social benefit 〉 economic benefit. The conclusion shows that the implementation of the national policy and the effect of mining area management meet the expectation. Therefore, this study provides effective reference and reasonable suggestions for soil and water conservation in Shendong Mining Area. In terms of control measures, bioengineering measures, such as increased coverage of forest and grass as well as reasonable transformation of the landscape pattern of micro landform, can improve the degree of soil erosion control, optimize the land use structure, and improve the land use rate.

Description: Collection systems in coastal cities are often below the groundwater table, leading to groundwater infiltration (GWI) through defects such as cracks and poor lateral connections. Climate-change-induced sea level rise (SLR) will raise groundwater levels, increasing the head and thus the inflow. A method has been developed to predict GWI when groundwater levels change using calibration with sewershed flow monitoring data. The calibration results in a parameter that characterizes the porosity of the collection system. A case study is presented for a coastal city with reliable flow monitoring data for eight days that resulted in a large range of effective defect sizes (minimum 0.0044 to maximum 0.338 radians), however, the range of predicted future GWI in currently submerged pipes varied by only 12% from the mean. The mean effective defect predicts 70 to 200% increases in GWI due to SLR of 0.3 to 0.9 m (1 to 3 ft), respectively, for currently submerged pipes. Predicted additional GWI for pipes that will become submerged due to SLR will increase GWI to values that approach or exceed the current average dry weather flow. This methodology can be used for planning of infrastructure improvements to enhance resiliency in coastal communities.

Description: Open surface freshwater is an important resource for terrestrial ecosystems. However, climate change, seasonal precipitation cycling, and anthropogenic activities add high variability to its availability. Thus, timely and accurate mapping of open surface water is necessary. In this study, a methodology based on the concept of spatial autocorrelation was developed for automatic water extraction from Landsat series images using Taihu Lake in south-eastern China as an example. The results show that this method has great potential to extract continuous open surface water automatically, even when the water surface is covered by floating vegetation or algal blooms. The results also indicate that the second shortwave-infrared band (SWIR2) band performs best for water extraction when water is turbid or covered by surficial vegetation. Near-infrared band (NIR), first shortwave-infrared band (SWIR1), and SWIR2 have consistent extraction success when the water surface is not covered by vegetation. Low filter image processing greatly overestimated extracted water bodies, and cloud and image salt and pepper issues have a large impact on water extraction using the methods developed in this study.

Description: Two recently constructed run-of-the-river dams (Santo Antônio and Jirau), along the Madeira River in Brazil, have been controversial due to their large unquantified impacts on (1) land use and land cover (LULC) and (2) on the area that would be flooded. Based on annual LULC data from 1985 to 2017, this study integrated intensity analysis and difference components methods to analyze the impacts of the two dams on the annual flooded area in upstream, midstream, and downstream regions of the Madeira River. The dam construction significantly influenced LULC change intensity in the upstream and midstream regions since 2011 and 2010, respectively. An increase of 18.5% of the newly flooded area (462.58 km2) in the post-dam construction period was observed. The water gross gain intensity was active during 2011–2017 and 2011–2014 in upstream and midstream, respectively. The dominant difference components of water change were exchanged in the pre-dam period and became quantity in the post-dam period for both upstream and midstream regions. Forest was the major land category replaced by water; however, the highest gain intensities occurred in other non-vegetated areas in upstream and midstream. This study provided a useful approach for characterizing impacts of dam construction on water area change.

Description: A study of a microalgae–bacteria treatment system was conducted in a sequencing batch reactor (SBR) by combining a precultured native algae Nannochloropsis gaditana L2 with spontaneous municipal wastewater microorganisms. Two types of agitation, air mixing (AI) and mechanical mixing (MIX), were assessed at continuous illumination (L) and photoperiod cycle light/dark (L/D). The obtained consortium, via native microalgae addition, has a better operational efficiency compared to spontaneous control. This allows the removal of 78% and 53% of total Kjeldhal nitrogen (TKN) and chemical oxygen demand (COD), respectively. Under the (L/D) photoperiod, the optimal removal rate (90% of TKN and 75% of COD) was obtained by the consortium at 4 days of hydraulic retention time (HRT) using the AI mode. Moreover, during feeding during dark (D/L) photoperiod, the highest removal rate (83% TKN and 82% COD) was recorded at 4 days HRT using the AI mode. These results bring, at the scale of a bioreactor, new data regarding the mode of aeration and the feeding time. They prove the concept of such a technology, increasing the attraction of microalgae-based wastewater treatment.

Description: The proliferation of antibiotic-resistant bacteria (ARB) and the prevalence of antibiotic resistance genes (ARGs) in wastewaters are well-established factors that contribute to the reduced potency of antibiotics used in healthcare worldwide. The human health risk associated with the proliferation of ARB and ARGs need to be understood in order to design mitigation measures to combat their dissemination. Using the PCR analysis of genomic DNA, the prevalence of 41 ARGs active against the commonly used six classes of antibiotics was evaluated in 60 bacterial isolates obtained from pharmaceutical wastewaters in Nigeria. The ARGs most frequently detected from the bacterial isolates in each of the antibiotic classes under study include catA1 (58.3%); sulI (31.7%); tet(E) (30%); aac(3)-IV (28.3%); ermC (20%); blaTEM, blaCTX-M, blaNDM-1 at 18.3% each; which encode for resistance to chloramphenicol, sulfonamides, tetracycline, aminoglycoside, macrolide-lincosamide-streptogramin and β-lactams and penicillins, respectively. Acinetobacter spp., accession number MH396735 expressed the highest number of ARGs of all the bacterial isolates, having at least one gene that encodes for resistance to all the classes of antibiotics in the study. This study highlights wide distribution of ARB and ARGs to the antibiotics tested in the wastewater, making pharmaceutical wastewater reservoirs of ARGs which could potentially be transferred from commensal microorganisms to human pathogens.

Description: Wooden fences are applied as a nature-based solution to support mangrove restoration along mangrove coasts in general and the Mekong Delta coast in particular. The simple structure uses vertical bamboo poles as a frame to store horizontal bamboo and tree branches (brushwood). Fence resistance is quantitatively determined by the drag coefficient exerted by the fence material on the flow; however, the behaviour of drag is predictable only when the arrangement of the cylinders is homogeneous. Therefore, for more arbitrary arrangements, the Darcy–Forchheimer equations need to be considered. In this study, the law of fluid flow was applied by forcing a constant flow of water through the fence material and measuring the loss of hydraulic pressure over a fence thickness. Fences, mainly using bamboo sticks, were installed with model-scale and full-scale diameters applying two main arrangements, inhomogeneous and staggered. Our empirical findings led to several conclusions. The bulk drag coefficient ( C D ¯ ) is influenced by the flow regime represented by Reynolds number. The drag coefficient decreases with the increase of the porosity, which strongly depends on fence arrangements. Finally, the Forchheimer coefficients can be linked to the drag coefficient through a related porosity parameter at high turbulent conditions. The staggered arrangement is well-predicted by the Ergun-relations for the Darcy–Forchheimer coefficients when an inhomogeneous arrangement with equal porosity and diameter leads to a large drag and flow resistance.

Description: Flow measurements were performed in the altered Yeongsan estuary, Korea, in August 2011, to investigate changes in flow structure in the water column and turbulence characteristics very close to the bed. Comparison between the bottom turbulent kinetic energy (TKE) and suspended sediment concentration (SSC) was conducted to examine how discrete freshwater discharge affects the bottom sediment concentration. The discrete freshwater discharge due to the gate opening of the Yeongsan estuarine dam induced a strong two-layer circulation: an offshore-flowing surface layer and a landward-flowing bottom layer. The fine flow structure from the bed to 0.35 m above the bottom (mab hereafter) exhibited an upside-down-bell-shaped profile for which current speed was nearly uniform above 0.1 mab, with the magnitude of the horizontal and vertical flow speeds reaching 0.1 and 0.01 m/s, respectively. The bottom turbulence responded to the freshwater discharge at the surface layer and the maximum magnitude of the Reynolds stress reached up to 2 × 10−4 m2/s2 during the discharged period, which coincided with increased SSC in the bottom boundary layer. These results indicate that the surface freshwater discharge due to opening of the estuarine dam gate increases the SSC by the discharge-induced intensification of the turbulent flow in the bottom boundary layer.

Description: Understanding the hydrologic and hydrochemistry processes in the riparian area is of great importance for managing and protecting riparian water resources. This paper took a highly disturbed and polluted Shaying River Basin (SRB) of China as the study area. In this research, environmental tracers (hydrochemical and isotopic data of222Rn, δ18O, and δD) and corresponding models (two-component mixing model and 222Rn mass balance model) were employed to investigate the hydrologic and associated hydro-chemical process of riparian groundwater. The results indicated that rivers received groundwater discharge located at Xihua (J8), Zhoukou (Y1), Luohe (S2), and Shenqiu (SY2), and the mixing extent with groundwater was greater in wet seasons than in dry seasons. The 222Rn mass balance model showed that the flux of river water leakage was 3.27 × 10−4 m3/(s·m) at the front of Zhoukou sluice while groundwater discharge was 3.50 × 10−3 m3/(s·m) at the front of Shenqiu sluice during the sampling period. The cation exchange and the dissolution/precipitation of aquifer minerals (including calcite, dolomite, gypsum, and halite) were dominated by geochemical processes. The untreated sewage discharge and fertilizer usage were the main anthropogenic activities affecting the hydrochemistry process in surface water and riparian groundwater. Additionally, our results found that nitrate pollutants derived by riparian groundwater were potential threats to river quality at the lower reaches of Jialu River and Shenqiu county of Shaying River, where the nitrate inputs could be larger during the wet seasons because of higher groundwater discharge.

Description: Due to simplicity and low costs, waste stabilisation ponds (WSPs) have become one of the most popular biological wastewater treatment systems that are applied in many places around the globe. Increasingly, pond modelling has become an interesting tool to improve and optimise their performance. Unlike process-driven models, generalised linear models (GLMs) can deliver considerable practical values in specific case studies with limited resources of time, data and mechanistic understanding, especially in the case of pond systems containing vast complexity of many unknown processes. This study aimed to investigate the key driving factors of dissolved oxygen variability in Ucubamba WSP (Ecuador), by applying and comparing numerous GLMs. Particularly, using different data partitioning and cross-validation strategies, we compared the predictive accuracy of 83 GLMs. The obtained results showed that chlorophyll a had a strong impact on the dissolved oxygen (DO) level near the water surface, while organic matter could be the most influential factor on the DO variability at the bottom of the pond. Among the 83 models, the optimal models were pond- and depth-specific. Specifically, among the ponds, the models of MPs predicted DO more precisely than those of facultative ponds; while within a pond, the models of the surface performed better than those of the bottom. Using mean absolute error (MAE) and symmetric mean absolute percentage error (SMAPE) to represent model predictive performance, it was found that MAEs varied in the range of 0.22–2.75 mg L−1 in the training period and 0.74–3.54 mg L−1 in the validation period; while SMAPEs were in the range of 2.35–38.70% in the training period and 10.88–71.62% in the validation period. By providing insights into the oxygen-related processes, the findings could be valuable for future pond operation and monitoring.

Description: Water resources planning and management depend on the quality of climatic data, particularly rainfall data, for reliable hydrological modeling. This can be very problematic in transboundary rivers with limited disclosing of data among the riparian countries. Satellite precipitation products are recognized as a promising source to substitute the ground-based observations in these conditions. This research aims to assess the feasibility of using a satellite-based precipitation product for better hydrological modeling in an ungauged and riparian river in Pakistan, i.e., the Chenab River. A semidistributed hydrological model of The soil and water assessment tool (SWAT) was set up and two renowned satellite precipitation products, i.e., global precipitation mission (GPM) IMERG-F v6 and tropical rainfall measuring mission (TRMM) 3B42 v7, were selected to assess the runoff pattern in Chenab River. The calibration was done from 2001–2006 with two years of a warmup period. The validation (2007–2010) results exhibit higher correlation between observed and simulated discharges at monthly timescale simulations, IMERG-F (R2 = 0.89, NSE = 0.82), 3B42 (R2 = 0.85, NSE = 0.72), rather than daily timescale simulations, IMERG-F (R2 = 0.66, NSE = 0.61), 3B42 (R2 = 0.64, NSE = 0.54). Moreover, the comparison between IMERG-F and 3B42, shows that IMERG-F is superior to 3B42 by indicating higher R2, NSE and lower percent bias (PBIAS) at both monthly and daily timescale. The results are strengthened by Taylor diagram statistics, which represent a higher correlation (R) and less RMS error between observed and simulated values for IMERG-F. IMERG-F has great potential utility in the Chenab River catchment as it outperformed the 3B42 precipitation in this study. However, its poor skill of capturing peaks at daily timescale remains, leaving a room for IMERG-F to improve its algorithm in the upcoming release.

Description: The objective of this research was to apply the flood vulnerability assessment to ungauged reservoirs for prioritizing and evaluating the reservoir rehabilitation according to climate change. The flood vulnerability index (FVI) can quantitatively compare the flood vulnerabilities of the analysis targets and can be used for the relative comparison of hydraulic structures to determine the reinforcement priority. In this study, we proposed a simple FVI that contained exposure and adaptive capacity of the hydraulic structure. We selected ten dam heightening reservoirs in Korea and constructed data for flood vulnerability assessment. The FVI was calculated before and after the dam heightening to analyze the priority and effect of reservoir rehabilitation under climate change. Flood vulnerability indices were estimated for four periods (1995s: 1981–2010, 2025s: 2011–2040, 2055s: 2041–2070, 2085s: 2071–2100) and before/after the dam heightening project. As a result, flood vulnerability indices decreased after the dam heightening project for all reservoirs, and the indices have increasing tendencies in the future. The indices developed in this study can be useful to determine the priority and to evaluate the effect of rehabilitation for hydraulic structures.

Description: The ecological environment is the foundation of human survival and development, and forest ecosystem nature reserves play an important role in the protection of the ecological environment. The evaluation of forest ecosystem nature reserves facilitates the formulation of relevant management policies. At present, the evaluation of the ecological environment of forest ecosystem nature reserves is mainly based on detailed evaluation of some elements of the ecological environment, rather than on a comprehensive quantitative evaluation that reflects the ecological environment in many aspects. To address this shortcoming, the quantitative evaluation indicator system of comprehensive ecological environment for forest ecosystem nature reserves was established based on the water, air, soil, and biological environments, according to the consensus on ecological environment in the past research and characteristics of the research area. The weight is still a necessary and important link in the evaluation of forest ecosystem nature reserves, but the accuracy of the weight results is difficult to get a scientific judgment. To prevent the evaluation results being influenced by weighting uncertainty, an unweighted cloud model was constructed to provide an evaluation mechanism without weight. The ecological environment evaluation was then carried out using the unweighted cloud model, taking Songshan Nature Reserve as a research area. The results show that the grades of the ecological environment of Songshan Nature Reserve are 21% excellent, 67% good, and 12% qualified, and that the state of the ecological environment is stable and performing well. The evaluation results for the grades of the environmental dimension layers are water environment 〉 soil environment 〉 biological environment 〉 air environment. The study’s research results can provide theoretical support for the evaluation of forest ecosystem nature reserves, and for evaluation work in general when weights are difficult to determine or uncertain.

Description: Bays are coastal environments with significant socio-economic importance, which has led to the development of human interventions in their interior that can have an important impact on the water and wave dynamics, which in turn modify their morphodynamics and water renewal capacity. In order to deepen our understanding of these impacts, numerical modeling was used in a bay in southern Spain to analyze the effect of inner harbor expansion and channel deepening, including the baroclinic and wave propagation effects, as well as variations in salinity and temperature. The results show that the deepening of the channel decreases the amplitude and speed of the tidal wave as it propagates through the bay, reducing the effects of friction and increasing the flushing time. The system evolves from convergent to a damping system that can potentially reduce the effects produced by projected sea level rise. In addition, the seasonal variability of salinity and temperature is reduced, increasing the bed shear stresses and resulting in increased turbidity that can affect the biogeochemistry of the bay. Finally, wave heights decrease along the main waterway, although the yearly-average wave energy flux is only slightly modified on the interior beaches of the bay. However, significant variations are observed during storms, which could affect the morphodynamics of these beaches.

Description: Accurate forecast of hydrological data such as precipitation is critical in order to provide useful information for water resources management, playing a key role in different sectors. Traditional forecasting methods present many limitations due to the high-stochastic property of precipitation and its strong variability in time and space: not identifying non-linear dynamics or not solving the instability of local weather situations. In this work, several alternative models based on the combination of wavelet analysis (multiscalar decomposition) with artificial neural networks have been developed and evaluated at sixteen locations in Southern Spain (semiarid region of Andalusia), representative of different climatic and geographical conditions. Based on the capability of wavelets to describe non-linear signals, ten wavelet neural network models (WNN) have been applied to predict monthly precipitation by using short-term thermo-pluviometric time series. Overall, the forecasting results show differences between the ten models, although an effective performance (i.e., correlation coefficients ranged from 0.76 to 0.90 and Root Mean Square Error values ranged from 6.79 to 29.82 mm) was obtained at each of the locations assessed. The most appropriate input variables to obtain the best forecasts are analyzed, according to the geo-climatic characteristics of the sixteen sites studied.

Description: Until now, there was no simple procedure to test the performance of water quality indices (WQIs) or, in other words, to perform their meta-evaluation. The purpose of this study is to provide a meta-evaluation approach of two widely used WQIs and suggestions for selecting one or both of them for application in groundwater quality assessment as proposed by the European Union. The meta-evaluation concept is based on testing the performance of two widely known WQIs by applying classification of Water Framework Directive (WFD; 2000/60/EC) and Groundwater Directive (GWD; 2006/118/EC) which was used as a reference. The Canadian Council of Ministers of Environment (CCME) and National Sanitation Foundation (NSF-WQI) have been selected for evaluation. These WQIs were applied in an agricultural area of the Mediterranean region where six sub-datasets for an entire hydrological year were available. This study uses all the available water quality data (52 monitoring stations × 2 sampling periods × 15 parameters) which is systematically collected at the area studied. The CCME-WQI is a rather strict index since it estimates statistically significantly lower values than the NSF-WQI. Based on the performance of the examined indices, it is shown that, mostly, the CCME-WQI classification findings are close to those of the GWD.

Description: The effective forecast and warning of pluvial flooding in real time is one of the key elements and remaining challenges of an integrated urban flood risk management. This paper presents a new methodology for integrating risk-based solutions and 2D hydrodynamic models into the early warning process. Whereas existing hydrodynamic forecasting methods are based on rigid systems with extremely high computational demands, the proposed framework builds on a multi-model concept allowing the use of standard computer systems. As a key component, a pluvial flood alarm operator (PFA-Operator) is developed for selecting and controlling affected urban subcatchment models. By distributed computing of hydrologic independent models, the framework overcomes the issue of high computational times of hydrodynamic simulations. The PFA-Operator issues warnings and flood forecasts based on a two-step process: (1) impact-based rainfall thresholds for flood hotspots and (2) hydrodynamic real-time simulations of affected urban subcatchments models. Based on the open-source development software Qt, the system can be equipped with interchangeable modules and hydrodynamic software while building on the preliminary results of flood risk analysis. The framework was tested using a historic pluvial flood event in the city of Aachen, Germany. Results indicate the high efficiency and adaptability of the proposed system for operational warning systems in terms of both accuracy and computation time.

Description: This paper focuses on regional integration through the lenses of the Water–Food–Energy (WEF) nexus, a concept putting strong emphasis on cross-sectoral and multi-level interactions as well as on resource interdependencies. There is an extensive amount of published research focusing on the Aral Sea basin. In this paper, the authors build upon these different contributions and provide a meta-analysis of the literature of WEF nexus opportunities in Central Asia (CA) countries. This paper contributes to ongoing discussions regarding how the WEF Nexus can represent an opportunity for reinforced collaboration regarding resources management. To do so, focusing on existing literature, this paper first (1) explores how the nexus can be a relevant instrument for regional integration. Second (2), it provides an overview of water, food, energy conditions and challenges in the Aral Sea basin in particular. Third (3), synthesizing existing research, the authors identify critical variables to be considered as hurdles or leverage points for WEF nexus implementation in the Aral Sea basin. Finally (4), we go back to our initial set of questions and identify some possible avenues for future research.

Description: The identification of aquifer parameters (i.e., specific yield and hydraulic conductivity) and forcing terms (recharge) is crucial for the process of modeling groundwater flow and contamination. Inversion techniques allow the unravelling of complex systems’ heterogeneity with more ease than manual calibration by computing parameter fields through an automated minimization between simulated and measured data (i.e., water head or measured aquifer parameters). It also allows the iterative search of multiple, equally plausible solutions, depending on system complexity (e.g., aquifer heterogeneity and variability of the forcing terms such as recharge). A Zoned Adaptive Multiscale Triangulation (ZAMT) is used for parameter estimation. ZAMT is the extension of an adaptive multiscale parameter estimation procedure already applied on different field cases. This extension consists of adding constraints varying over the domain. The ZAMT dissociates the parameter grid from the calculation mesh and allows local parameter grid refinement depending on local criteria, addressing the ill-posedness of inversion problems, decreasing computation time by reducing the amount of possible solutions and local minima, and ensuring flexibility in the parameter’s distribution. Each parameter is defined per vertex of the parameter grid; it can be set with a different range of values in order to integrate more pedo-geological information and help the optimization process by reducing the number of local minima. For the same purpose, a plausibility term based on topological characteristics of the aquifer or minimal and maximal water levels is added to the objective function. Groundwater flow is described by a classical nonlinear diffusion-type equation (unconfined aquifer), which is discretized with a two-dimensional nonconforming finite element method because water head data is unsuitable to invert three-dimensional parameter fields. Therefore, flow is considered mainly horizontal, and the parameters are obtained as average values on the saturated thickness. The study area is an alluvial (unconfined) aquifer of 6.64 km², situated in the southern, Mediterranean part of France. The simulation runs with a chronicle of 191 piezometers over 7 years (2012–2019), using a calibration period of 5 years (2012–2016). The optimization threshold is set to ensure a mean absolute error below 40 cm. The ZAMT and the additional plausibility criterion were found to produce an ensemble of realistic parameter sets with low parameter standard deviation. The model is considered robust as the water head error remains at the same level during the verification period, which includes an exceptionally dry year (2017). Overall, the calibration is best near the rivers (Dirichlet boundaries), while the terraced portion of the site challenges the limits of the 2D approach and the inversion procedure.

Description: Rainwater-harvesting (RWH) agriculture has been accepted as an effective approach to easing the overexploitation of groundwater and the associated socioeconomic impacts in arid and semiarid areas. However, the stability and reliability of the traditional methods for selecting optimal sites for RWH agriculture need to be further enhanced. Based on a case study in Tehran Province, Iran, this study proposed a new decision support system (DSS) that incorporates the Best-Worst Method (BWM) and Fuzzy logic into a geographic information system (GIS) environment. The probabilistic analysis of the rainfall pattern using Monte Carlo simulation was conducted and adopted in the DSS. The results have been demonstrated using suitability maps based on three types of RWH systems, i.e., pans and ponds, percolation tanks, and check dams. Compared with traditional methods, the sensitivity analysis has verified that the proposed DSS is more stable and reliable than the traditional methods. Based on the results, a phase-wise strategy that shifts the current unsustainable agriculture to a new paradigm based on RWH agriculture has been discussed. Therefore, this DSS has enhanced the information value and thus can be accepted as a useful tool to ease the dilemma resulting from unsustainable agriculture in arid and semiarid areas.

Description: Soil moisture is a critical parameter in numerical weather prediction (NWP) models because it plays a fundamental role in the exchange of water and energy cycles between the atmosphere and the land surface through evaporation. To improve the forecast skills of the Weather Research and Forecasting (WRF) model in Xinjiang, China, this study investigated the impacts of soil moisture initialization on the WRF forecasts by performing a series of simulations. A group of simulations was conducted using the single-column model (SCM) from 1200 UTC on 15 to 18 August 2019, at Urumchi, Xinjiang (43.78° N, 87.6° E); another was performed using the WRF model for a real weather case in Xinjiang from 0000 UTC 15 August to 1200 UTC 18 August 2019, which included an episode of heavy precipitation and gales. Our most notable findings are as follows. Specific humidity increases and potential temperature decreases persistently when soil moisture increases because of soil water evaporation. Soil moisture initialization could impact the energy budget and modulate the partition of the total available energy at the land surface significantly through evaporation and the greenhouse effect. Replacing the soil moisture with a proper multiple of the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) soil moisture data could significantly improve the critical success index (CSI) and frequency bias (FBIAS) of precipitation and the root-mean-squared errors (RMSEs) of 2-m specific humidity and 2-m temperature. These findings indicate the prospect of a new way to improve the forecast skills of WRF in Xinjiang or other similar regions.

Description: The localization of groundwater contaminant sources is the first and most fundamental step when dealing with site contamination problems. This paper presents a novel approach for groundwater pollution source identification in a site with low-velocity groundwater in which a strategy of an artificially enhanced catchment is adopted. The distance from a pumping well (artificial sink) to the source zone (unknown source) is calculated by integrating the concentration time series and well flow. Then, the orientation of the source well is delineated by applying the method of distance intersection. This method is suitable for an approximately homogeneous aquifer with average hydraulic conductivity ranging from 1 × 10−6 to 1 × 10−5 m/s and a contaminant whose transport process can be generalized to convective migration. The developed method was applied to an industrial contaminated site using three pumping wells and two observation wells. The results demonstrated that four potential source positions were identified. Among these, two positions situated near the production workshop were excluded by observation well responses. The remaining two positions located near the drain were identified as preferred treatment sources. Electrical prospecting showed source orientation consistent with the artificially enhanced catchment results. This proved that the method is effective and provides an alternative tool to help solve the problem of source identification in the first stage of remediation in sites with low-velocity groundwater.

Description: Heavy rain damage prediction models were developed with a deep learning technique for predicting the damage to a region before heavy rain damage occurs. As a dependent variable, a damage scale comprising three categories (minor, significant, severe) was used, and meteorological data 7 days before the damage were used as independent variables. A deep neural network (DNN), convolutional neural network (CNN), and recurrent neural network (RNN), which are representative deep learning techniques, were employed for the model development. Each model was trained and tested 30 times to evaluate the predictive performance. As a result of evaluating the predicted performance, the DNN-based model and the CNN-based model showed good performance, and the RNN-based model was analyzed to have relatively low performance. For the DNN-based model, the convergence epoch of the training showed a relatively wide distribution, which may lead to difficulties in selecting an epoch suitable for practical use. Therefore, the CNN-based model would be acceptable for the heavy rain damage prediction in terms of the accuracy and robustness. These results demonstrated the applicability of deep learning in the development of the damage prediction model. The proposed prediction model can be used for disaster management as the basic data for decision making.

Description: Temporarily closed estuaries require seasonal opening to tidal flows to maintain normalecological processes. Each estuary has specific environmental flow (EFlow) requirements basedon the relationship between freshwater inflow, coastal dynamics, rate of sandbar formation,and the open/closed state of the mouth. Key abiotic processes and ecosystem services linkedto mouth state were highlighted. We reviewed completed EFlow requirement studies for temporarilyclosed estuaries in South Africa and found that the formulation of these requirements shouldconsider the timing and magnitude of flows in relation to the morphology of an estuary, its mouthstructure, catchment size, and climate. We identified ten key principles that could be adapted tosimilar systems in equivalent climatic settings. Principle 1 recognizes that each estuary is unique interms of its EFlow requirements because size, scale, and sensitivity of core elements to freshwaterinflow are specific for each system; EFlows cannot be extrapolated from one estuary to another.Principle 2 highlights the importance of baseflows in keeping an estuary mouth open because a smallreduction in flow can cause the mouth to close and alter essential ecological processes. Principle 3outlines the role of floods in resetting natural processes by flushing out large volumes of sedimentand establishing the equilibrium between erosion and sedimentation. Principle 4 emphasizes the needfor open mouth conditions to allow regular tidal flushing that maintains water quality throughreducing retention times and preventing the onset of eutrophic conditions. Principle 5 advisesartificial breaching to be practiced with caution because execution at low water levels encouragessedimentation that reduces the scouring eect of flushing. Principle 6 holds that elevated inflowvolumes from wastewater treatment works or agricultural return flows can increase the frequency ofmouth opening and cause ecological instability. Principle 7 states that water released from dams tosupply the environmental flow cannot mimic the natural flow regime. Principle 8 specifies the needfor short- and long-term data to increase the confidence levels of EFlow assessments, with data tobe collected during the open and closed mouth states. Principle 9 advocates the implementation ofa monitoring program to track the achievement of EFlow objectives as part of a strategic adaptivemanagement cycle. Finally, Principle 10 recommends the adoption of a holistic catchment-to-coastmanagement approach underpinned by collaboration with regulatory authorities and stakeholdersacross a range of sectors. These principles can be used to guide the formulation and managementof EFlows, an essential strategy that links the maintenance of estuarine ecological integrity withsocial well-being.

Description: Urban development causes multiple water losses. Some of them may be ignored but some could have a huge influence on the whole catchment, including soil drought. As urban sprawl rises, space for unaffected infiltration and retention is increasingly limited. The objective of this study was to backcast and to estimate water-retention loss due to urbanization during the period of 1990–2018. We used landcover data, meteorological and hydrological data and data on soil water-holding capacity. Water-retention loss was expressed as soil water retention capacity loss, net precipitation loss and total sum of precipitation loss. Historical change in urban extension has led to large impacts on the hydrological cycle of the study area. Progressive urban development caused water-retention losses which range from 3.380 to 14.182 millions of cubic meters—depending on the methodology used. Hydrological analysis showed the lack of a significant trend (decrease trend) of low flow which is caused by the high percentage of natural land use in the upper part of catchment. Our results show that backcasting of water retention change using CLC data (a) brings new and plausible data on retention loss, (b) is possible to replicate and (c) data used are common and easy-to-get.

Description: The potential impact of climate variability on the hydrological regime in the Mahanadi river basin is of great importance for sustainable water resources management. The impact of climate variability on streamflow is analyzed in this study. The impact of climate variability modes on extreme events of Mahanadi basin during June, July, and August (JJA), and September, October, and November (SON) seasons were analyzed, with daily streamflow data of four gauge stations for 34 years from 1980 to 2013 found to be associated with the sea surface temperature variations over Indo-Pacific oceans and Indian monsoon. Extreme events are identified based on their persistent flow for six days or more, where selection of the stations was based on the fact that there was no artificially regulated streamflow in any of the stations. Adequate scientific analysis was done to link the streamflow variability with the climate variability and very significant correlation was found with Indian Ocean Dipole (IOD), El Nino Southern Oscillation (ENSO), El Nino Modoki Index (EMI), and Indian monsoon. Agriculture covers major portion of the basin; hence, the streamflow is very much essential for agriculture as well as population depending on it. Any disturbances in the general flow of the river has subjected an adverse impact on the inhabitants’ livelihood. While analyzing the correlation values, it was found that all stations displayed a significant positive correlation with Indian Monsoon. The respective correlation values were 0.53, 0.38, 0.44, and 0.38 for Andhiyarkore, Baronda, Rajim, and Kesinga during JJA season. Again in the case of stepwise regression analysis, Monsoon Index for the June, July, and August (MI-JJA) season (0.537 for Andhiyarkore) plays significant role in determining streamflow of Mahanadi basin during the JJA season and Monsoon Index for July, August, and September (MI-JAS) season (0.410 for Baronda) has a strong effect in affecting streamflow of Mahanadi during the SON season. Flood frequency analysis with Weibull’s plotting position method indicates future floods in the Mahanadi river basin in JJA season.

Description: The aim of this study was to determine the effect of trout aquaculture effluents on the Drwęca River. The count of opportunistic pathogen Pseudomonas fluorescens (OPPF) in the total Pseudomonas fluorescens population (TPFP) were determined by plating on King B medium and fluorescence in situ hybridization. The resistance of OPPF strains to 12 antibiotics and two disinfectants was evaluated. Significant differences (p ≤ 0.05) in OPPF counts were found between seven sampling sites. OPPF counts were highest in samples collected directly downstream from three fish farms. More than 50% of these isolates demonstrated multiple-drug resistance to ampicillin, mezlocillin, cefotaxime, norfloxacin, tetracycline and two disinfectants (Steridial and chloramine T). Of these, 52% were resistant to high doses of cefotaxime and norfloxacin (MIC ≥ 256 µg·mL−1), and 65% were resistant to the maximum doses of Steridial (MIC Ste ≥ 25 mL·m−3) and chloramine T (MIC Chlor ≥ 20 mg·L−1). All OPPF sampled upstream from the farms were sensitive to low concentrations of CTX (cefotaxime) and NOR (norfloxacin) (MIC ≤ 2 µg·mL−1), Steridial (MIC Ste ≤ 5 mL·m−3) and chloramine T (MIC Chlor ≤ 2.5 mg·L−1). Agglomerative clustering revealed two clusters: strains from samples collected upstream and downstream from trout farms. The results indicate that aquaculture effluents significantly affect the prevalence of biocides resistant OPPF along the river continuum.

Description: The diffusion and sealing mechanisms of cement-sodium silicate grout (C-S grout), which is widely used in flowing water sealing projects, are complicated. Based on a large-scale quasi-three-dimensional simulation test platform of fracture dynamic water grouting, an orthogonal experiment of flowing-water sealing of C-S grout was performed. The grout was shown to diffuse in the form of an asymmetric ellipse. The flowing-water sealing process consists of three stages: (1) the grout diffuses to the fracture boundary in an asymmetrical ellipse; (2) the solidified body of grout develops; (3) the stable solidified body forms. The sealing efficiency was evaluated and graded by the reduction of water drainage through the fracture after grouting. Based on the test data, the factors that affect sealing efficiency can be listed in the following order from strong to weak: grout gel time, flowing water velocity, grout take, fracture plane width, and fracture aperture. Finally, a fitting equation was acquired to provide a reference for practical engineering applications.

Description: Accurate and reliable estimates of water levels are essential to assess flood risk in river systems. In current practice, uncertainties involved and the sensitivity of water levels to these uncertainties are studied in single-branch rivers, while many rivers in deltas consist of multiple distributaries. In a bifurcating river, a feedback mechanism exists between the downstream water levels and the discharge distribution at the bifurcation. This paper aims to quantify the sensitivity of water levels to main channel roughness in a bifurcating river system. Water levels are modelled for various roughness scenarios under a wide range of discharge conditions using a one-dimensional hydraulic model. The results show that the feedback mechanism reduces the sensitivity of water levels to local changes of roughness in comparison to the single-branch river. However, in the smaller branches of the system, water-level variations induced by the changes in discharge distribution can exceed the water-level variations of the single-branch river. Therefore, water levels throughout the entire system are dominated by the conditions in the largest branch. As the feedback mechanism is important, the river system should be considered as one interconnected system in river maintenance of rivers, flood-risk analyses, and future planning of river engineering works.

Description: The proper planning of storage structures, waterways, irrigation schemes, water harvesting, erosion control structures, and groundwater development strategies requires accurate estimation of surface runoff. However, hydrologists in Saudi Arabia face serious challenges, specifically due to the rare availability of surface runoff data. In this study, the soil conservation service-curve number (SCS-CN) method integrated with geographic information system (GIS) and remote sensing (RS) was utilized to estimate the surface runoff in Wadi-Uranah basin, in the western region of Saudi Arabia. Different thematic maps such as slope, hydrologic soil group (HSG), land use/land cover (LULC), and daily rainfall have been created in GIS environment and processed to generate the curve number (CN) and surface runoff maps. Based on the soil classification results, the study area was categorized into two HSGs (B and C). The dominant HSG was group C, representing about 98.8% of the total area. The LULC analysis showed four main land use types in the study region: urban, rocks, barren soil, and agricultural areas. Furthermore, the finding results showed that CN values for the normal conditions (CNII) ranged between 74 and 93 in agricultural and both urban and rock areas, respectively. The CNII values were further corrected using slope data to derive slope-adjusted CNII. Moreover, the rainfall-runoff results showed an increase in the daily runoff of the study region with a minimum of 15 mm to a maximum of 74 mm. Another interesting result was rainfall-runoff linear regression analysis that showed a good correlation of 0.98. Additionally, the peak runoff hydrograph flows for 10-, 50-, and 100-year return periods obtained from the SCS-based dimensionless unit hydrograph were 828, 1353, and 1603 m3/s, respectively. Therefore, this study highlights that the SCS-CN method integrated with RS and GIS deserves further attention for estimating runoff of ungauged basins for better basins management and conservation purposes.

Description: Treatment of water saturated with CO2 with low-temperature, low-pressure glow plasma of low-frequency (GP) produced a series of liquids. Their temperature and intensity of thermal effects non-linearly depended on the treatment time. However, the Raman spectra patterns of the treated water pointed to a specific structure of the water treated for 30 min. The spectra of control, non-treated water saturated with CO2, and such water treated for 15, 60, 90, and 120 min showed that their macrostructure was built mainly by a single donor, and single hydrogen bonded arrangements accompanied, to a certain extent, with free water molecules. The macrostructure of the water treated for 30 min consisted chiefly of tetrahedral and deformed tetrahedral structural units. That water contained long-living free radicals of discussed structure, stabilized in such macrostructure.

Description: The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes temperature into account, but the SPI does not. In the context of global warming, what are their differences and applicability in regional drought monitoring? In this study, after calculating the SPI and SPEI at 1-, 3-, 6-, and 12-month timescales at 102 meteorological stations in Inner Mongolia from 1981 to 2018, we compared and analyzed the performances of the SPI and SPEI in drought monitoring from temporal and spatial variations, and the consistency and applicability of the SPI and SPEI were also discussed. The results showed that (1) with increasing timescale, the temporal variations in the SPI and SPEI were increasingly consistent, but there were still slight differences in the fluctuation value and continuity; (2) due to the difference in time series, the drought characteristics identified by the SPI and SPEI were quite different in space at various timescales, and with the increase in timescale, the spatial distributions of the drought trends in Inner Mongolia were basically consistent, except in Alxa; (3) at the shortest timescale, the difference between the SPI and SPEI was the largest, and the drought reflected by the SPI and SPEI may be consistent at long timescales; and (4) compared with typical drought events and vegetation indexes, the SPEI may be more suitable than the SPI for drought monitoring in Inner Mongolia. It should be noted that the adaptability of the SPI and SPEI may be different in different periods and regions, which remains to be analyzed in the future.

Description: Water is a key and limiting factor for ecosystem processes (carbon dioxide fixation, vegetation growth, respiration, etc.) and functions (NPP, Net Primary Productivity) in arid and semi-arid areas. As the main regulator, knowledge of plant water use patterns is essential in understanding the SPAC (Soil-Plant-Atmosphere-Continuum) cycle. The tree-planting project in the southern and northern mountains of Lanzhou city aims to improve the ecological environment and promote urban construction. In this study, we analyzed the water use strategies of the dominant plants C. korshinskii and R. soongorica in natural shrubs of southern and northern mountains of Lanzhou city using oxygen stable isotope techniques. The result showed that the flexible water uptake pattern of C. korshinskii and its faster response to precipitation pulse, compared with R. soongorica, might help it to make full use of water and nutrients and adapt to the dry environment. However, R. soongorica progressively switched to suck up deeper soil water and increased the water use proportion from 0.5% to 84.4% as the seasons changed, indicating a greater degree of ecological plasticity. The flexible water use strategies of C. korshinskii and R. soongorica in the same habitat reduced competition for water and nutrients and enhanced adaptability to arid environments. The work presented here provides insights into vegetation restoration and ecological management for the southern and northern mountains of Lanzhou city.

Description: Fungi are an important, yet often, neglected component of the aquatic microflora, and is responsible for primary decomposition and further processing of organic matter. By comparison, the ecological roles of terrestrial fungi have been well-studied, but the diversity and function of fungi that populate aquatic environments remain poorly understood. Here, the impact of urbanization on fungal diversity and community composition in the canal system of Suzhou was assessed by sequencing the internal transcribed spacer 1 (ITS1) region of the rRNA operon. It was amplified from environmental DNA that has been extracted from water samples and pre-deployed decomposing leaves collected from nine sampling locations (high, medium and low urbanization) over two seasons. The fungal diversity and community composition were determined by bioinformatic analysis of the large DNA sequence datasets generated to identify operational taxonomic units (OTUs) for phylogenetic assignment; over 1 million amplicons were sequenced from 36 samples. The alpha-diversity estimates showed high differences in fungal diversity between water and leaf samples, and winter versus summer. Higher numbers of fungal OTUs were identified in both water and leaf samples collected in the summer, and fungal diversity was also generally higher in water than on colonized leaves in both seasons. The fungal community on leaves was usually dominated by Ascomycetes, especially in winter, while water samples contained more diversity at phylum level with Chytridiomycetes often prominent, particularly in summer. At a genus level, a very high relative abundance of Alternaria on leaves was observed in winter at all locations, in contrast to very low abundance of this genus across all water samples. Fungal community composition also varied between sampling locations (i.e., urbanization); in cluster analysis, samples from high urbanization locations formed a distinct cluster, with medium and low urbanization samples clustering together or in some instances, separately. Redundancy analysis shed further light on the relationships between variation in fungal community composition and water physico-chemical properties. Fungal community diversity variation and correlation with different parameters is discussed in detail, but overall, the influence of season outweighed that of urbanization. This study is significant in cataloguing the impact of urbanization on fungal diversity to inform future restoration of urban canal systems on the importance of protecting the natural aquatic fungal flora.

Description: This paper presents an extended Model Predictive Control scheme called Multi-objective Model Predictive Control (MOMPC) for real-time operation of a multi-reservoir system. The MOMPC approach incorporates the non-dominated sorting genetic algorithm II (NSGA-II), multi-criteria decision making (MCDM) and the receding horizon principle to solve a multi-objective reservoir operation problem in real time. In this study, a water system is simulated using the De Saint Venant equations and the structure flow equations. For solving multi-objective optimization, NSGA-II is used to find the Pareto-optimal solutions for the conflicting objectives and a control decision is made based on multiple criteria. Application is made to an existing reservoir system in the Sittaung river basin in Myanmar, where the optimal operation is required to compromise the three operational objectives. The control objectives are to minimize the storage deviations in the reservoirs, to minimize flood risks at a downstream vulnerable place and to maximize hydropower generation. After finding a set of candidate solutions, a couple of decision rules are used to access the overall performance of the system. In addition, the effect of the different decision-making methods is discussed. The results show that the MOMPC approach is applicable to support the decision-makers in real-time operation of a multi-reservoir system.

Description: Wetlands are environments whose water balance is highly sensitive to climate change and human action. This sensitivity has allowed us to explore the relationships between surface water and groundwater in the long term as their sediments record all these changes and go beyond the instrumental/observational period. The Lagunas Reales, in central Spain, is a semi-arid inland wetland endangered by both climate and human activity. The reconstruction of the hydroclimate and water levels from sedimentary facies, as well as the changes in the position of the surface water and groundwater via the record of their geochemical fingerprint in the sediments, has allowed us to establish a conceptual model for the response of the hydrological system (surface water and groundwater) to climate. Arid periods are characterized by low levels of the deeper saline groundwater and by a greater influence of the surface freshwater. A positive water balance during wet periods allows the discharge of the deeper saline groundwater into the wetland, causing an increase in salinity. These results contrast with the classical model where salinity increases were related to greater evaporation rates and this opens up a new way of understanding the evolution of the hydrology of wetlands and their resilience to natural and anthropogenic changes.

Description: Rain gauges continue to be sources of rainfall data despite progress made in precipitation measurements using radar and satellite technology. There has been some work done on assessing the optimum rain gauge network density required for hydrological modelling, but without consensus. This paper contributes to the identification of the optimum rain gauge network density, using scaling laws and bias-corrected 1 km × 1 km grid radar rainfall records, covering an area of 28,371 km2 that hosts 315 rain gauges in south-east Queensland, Australia. Varying numbers of radar pixels (rain gauges) were repeatedly sampled using a unique stratified sampling technique. For each set of rainfall sampled data, a two-dimensional correlogram was developed from the normal scores obtained through quantile-quantile transformation for ordinary kriging which is a stochastic interpolation. Leave-one-out cross validation was carried out, and the simulated quantiles were evaluated using the performance statistics of root-mean-square-error and mean-absolute-bias, as well as their rates of change. A break in the scaling of the plots of these performance statistics against the number of rain gauges was used to infer the optimum rain gauge network density. The optimum rain gauge network density varied from 14 km2/gauge to 38 km2/gauge, with an average of 25 km2/gauge.

Description: International water institutions worldwide consider integrated water resources management (IWRM) to be the most sustainable way to manage water. Governments have modified their legal and institutional framework in order to apply integrated water management tools in the river basin. Institutional challenges are common in federations due to complex power sharing at national and subnational levels. This article discusses the implementation of the hegemonic model of IWRM in federations, based on a review of the literature for two different federal countries: Brazil and Switzerland. Due to the centralized character of Brazilian federalism, adjustments made in recent decades aimed to adapt the water management model through a hegemonic approach of participation and decentralization, shaped by international experiences and institutions. Some challenges concern vertical interplay, concerning coordination between levels and effective implementation of decentralization and participation. In contrast, Switzerland has a non-hegemonic model of water management, which is varied and fragmented throughout the country. As management is decided and applied locally, the main challenge concerns horizontal interplay, with regionalization and coordination of water uses.

Description: Environmental sampling plays an important role in quantitative and qualitative investigation of plastic pollution. Rivers are a major source, carrying plastic litter into the oceans. Microplastic sampling in riverine and coastal environments is often a challenging task due to limited access, time taken, costs, human resources, etc. Our present study evaluated the performance of newly developed sampling devices (Albatross Mark 5 and 6 (AM-5 and AM-6)) that were suitable to collect floating and suspended microplastic samples in challenging freshwater and coastal environments (95 locations). Our observations indicated a similar magnitude of microplastic concentrations with AM-5 and AM-6 sampling compared to conventional plankton nets. The sampling duration, originally 10–60 min (by plankton net), was reduced to 3 min (AM-5 and AM-6) for sampling water volumes of approximately 10 m3. The developed AM-6 device was used to collect samples from riverine and coastal environments in Japan. The microplastic particle polymer composition (using Fourier transform infrared spectrophotometry (FT-IR)), size, and shape (microscopic images) were investigated. The observations showed a statistically significant particle size reduction from the riverine to coastal areas. The dominant polymer types detected were polyethylene (PE) and polypropylene (PP). The observations were complied with the coastal microplastic observations that were reported for previous studies in Japanese water environments.

Description: Effective precipitation plays an important role in crop growth, and subsoiling may have an impact on the effective precipitation of farmland. The question how subsoiling influences effective precipitations has prompted this research. The major objective of this study was to quantify the effect of subsoiling on effective precipitation of farmland. The main soil type in the study area is loam. Six scenarios were set with three factors, namely, the thickness of the soil ploughing layer, porosity, and soil permeability. The hydrological process from 2000 to 2015 was simulated with a distributed hydrological model. The results showed that a 10-cm increase in the soil thickness of the plough layer had little effect on the effective precipitation. When soil porosity increased by 0.1, the effective precipitation increased by approximately 19%. When the soil permeability coefficient increased by 0.5 times, the farmland and watershed surface runoff decreased by 24% and 13%, respectively, and the effective precipitation increased by 1.7%. This study proves that subsoiling has a positive effect on the local effective precipitation and confirms previous hypotheses.

Description: Precipitation estimates from numerical weather prediction (NWP) models are uncertain. The uncertainties can be reduced by integrating precipitation observations into NWP models. This study assimilates Version 04 Integrated Multi-satellite Retrievals for the Global Precipitation Measurement (GPM) (IMERG) Final Run into the Weather Research and Forecasting (WRF) model data assimilation (WRFDA) system using a four-dimensional variational (4D-Var) method. Three synoptic-scale convective precipitation events over the central United States during 2015–2017 are used as case studies. To investigate the effect of logarithmically transformed IMERG precipitation in the WRFDA system, this study reports on several experiments with six-hour and hourly assimilation windows, regular (nontransformed) and logarithmically transformed observations, and a constant observation error in regular and logarithmic spaces. Results show that hourly assimilation windows improve precipitation simulations significantly compared to six-hour windows. Logarithmically transformed precipitation does not improve precipitation estimations relative to nontransformed precipitation. However, better predictions of heavy precipitation can be achieved with a constant error in the logarithmic space (corresponding to a linearly increasing error in the regular space), which modifies the threshold of rejecting observations, and thus utilizes more observations. This study provides a cost function with logarithmically transformed observations for the 4D-Var method in the WRFDA system for future investigations.

Description: Based on statistical data of the average abundance of microplastics from 37 global freshwater locations up to November 2019, we classified the freshwater bodies according to developments in their local countries and geographic positions. We highlighted the differences and causes of microplastic pollution in the waters of both developed and developing countries and urban and rural areas. The results showed that microplastic pollution was highest in Asia. The pollution in developed countries was significantly lower than in developing countries. The differences in freshwater pollution between urban and rural areas mainly depended on the extent of human activity. The present study found the following phenomena by comprehensively using simple and multiple regression models and a Pearson correlation analysis to solve the impacts of the features, natural factors, and social and economic factors on the distribution of microplastic pollution. The density of microplastics was higher, which promoted the aggregation of microplastics in sediments. Pursuant to that, microplastic pollution was also influenced by the space-time pollution of movable surface sources, such as the soil and air. A population increase and the average gross domestic product (GDP) could also worsen microplastic pollution.

Description: Recently, the quality of fresh water resources is threatened by numerous pollutants. Prediction of water quality is an important tool for controlling and reducing water pollution. By employing superior big data processing ability of deep learning it is possible to improve the accuracy of prediction. This paper proposes a method for predicting water quality based on the deep belief network (DBN) model. First, the particle swarm optimization (PSO) algorithm is used to optimize the network parameters of the deep belief network, which is to extract feature vectors of water quality time series data at multiple scales. Then, combined with the least squares support vector regression (LSSVR) machine which is taken as the top prediction layer of the model, a new water quality prediction model referred to as PSO-DBN-LSSVR is put forward. The developed model is valued in terms of the mean absolute error (MAE), the mean absolute percentage error (MAPE), the root mean square error (RMSE), and the coefficient of determination ( R 2 ). Results illustrate that the model proposed in this paper can accurately predict water quality parameters and better robustness of water quality parameters compared with the traditional back propagation (BP) neural network, LSSVR, the DBN neural network, and the DBN-LSSVR combined model.

Description: Recovery of tide-receiving is considered to improve the water quality in the Lianjiang River, a severely polluted and tide-influenced river connected to the South China Sea. A tide-receiving scenario, i.e., keeping the tide gate open, is compared with the other scenario representing the non-tide-receiving condition, i.e., blocking the tide flow during the flood phase, by numerical simulations based on the EFDC (Environmental Fluid Dynamics Code) model. The impacts of tide receiving were evaluated by the variation in the concentration of ammonia and its exporting fluxes, mainly in the downstream part of the river. With more water mass coming into the river, in the tide-receiving scenario, the averaged concentration of ammonia reduced by 20–40%, with the most significant decrease of 0.64 g m−3. However, the exporting flux of ammonia has decreased in the tide-receiving scenario, as the consequence of the back–forth oscillation of tidal current. In the tide-receiving scenario, the time series of ammonia concentration approximately followed the tidal oscillation, with increased concentration during the ebb tide and reduction in the flood tide. In the non-tide-receiving scenario, the ammonia concentration decreases when the tide gate is open which results in further intrusion of seawater. This was followed by an increase in ammonia concentration again after the currents shift seaward and water mass with higher concentration from the upstream part is transported downstream. Given the identical ammonia input and river runoff, the ammonia concentration stays lower in the tide-receiving scenario, except for short periods after the tide gate opening and neap tides in the downstream part which lasts for around half a day. This study highlights the importance of hydrodynamic condition, specifically tidal oscillation, in the semi-diurnal and fortnight cycles, for the transportation of waterborne materials. Furthermore, the operation of the tide gate was additionally discussed based on potential varied practical conditions and evaluation criteria.

Description: In this study, a lab-scale plant was designed to treat water in continuous flow condition using non-thermal plasma technology. The core was an electrode system with connected high-voltage (HV) pulse generator. Its potentials and limitations were investigated in different experimental series with regard to the high-voltage settings, additions of oxygen-based species, different volume flow rates, and various physical-chemical properties of the process water such as conductivity, pH value, and temperature. Indigo carmine, para-Chlorobenzoic acid, and phenol were chosen as reference substances. The best HV settings was found for the voltage amplitude Û = 30 kV, the pulse repetition rate f = 0.4–0.6 kHz, and the pulse duration tb = 500 ns with an energy yield for 50% degradation G50, which is of 41.8 g∙kWh−1 for indigo carmine, 0.32 g∙kWh−1 for para-Chlorobenzoic acid, and 1.04 g∙kWh−1 for phenol. By adding 1 × 10−3 mol∙L−1 of oxygen, a 50% increase in degradation was achieved for para-Chlorobenzoic acid. Conductivity is the key parameter for degradation efficiency with a negative exponential dependence. The most important species for degradation are hydroxyl radicals (c ≈ 1.4 × 10−8 mol∙L−1) and solvated electrons (c ≈ 1.4 × 10−8 mol∙L−1). The results show that the technology could be upgraded from the small-scale experiments described in the literature to a pilot plant level and has the potential to be used on a large scale for different applications.

Description: The last few decades have witnessed a tremendous increase in nutrient levels (phosphorus and nitrogen) in coastal water leading to excessive algal growth (Eutrophication). The presence of large amounts of algae turns the water’s color into green or red, in the case of algal blooms. Chlorophyll-a is often used as an indicator of algal biomass. Due to increased human activities surrounding Dubai creek, there have been eutrophication concerns given the levels of nutrients in that creek. This study aims to map chlorophyll-a in Dubai Creek from WorldView-2 imagery and explore the relationship between chlorophyll-a and other eutrophication indicators. A geometrically- and atmospherically-corrected WorldView-2 image and in-situ data have been utilized to map chlorophyll-a in the creek. A spectral model, developed from the WorldView-2 multispectral image to monitor Chlorophyll-a concentration, yielded 0.82 R2 with interpolated in-situ chlorophyll-a data. To address the time lag between the in-situ data and the image, Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images were used to demonstrate the accuracy of the WorldView-2 model. The images, acquired on 20 May and 23 July 2012, were processed to extract chlorophyll-a band ratios (Band 4/Band 3) following the standard approach. Based on the availability, the 20 May image acquisition date is the closest to the middle of Quarter 2 (Q2) of the in-situ data (15 May). The 23 July 2012 image acquisition date is the closest to the WorldView-2 image date (24 July). Another model developed to highlight the relationship between spectral chlorophyll-a levels, and total nitrogen and orthophosphate levels, yielded 0.97 R2, which indicates high agreement. Furthermore, the generated models were found to be useful in mapping chlorophyll-a, total nitrogen, and orthophosphate, without the need for costly in-situ data acquisition efforts.

Description: Meteorological data from vegetated and un-vegetated wetlands during wet and dry seasons, were collected and analyzed to evaluate the role of wind and vegetation on wetlands’ hydrology. Wind speed diminished by as much as 40%, accompanied by a measurable change in wind directions in the vegetated compared to the open water site. Wind speed and direction means were significantly different (p 〈 0.001 and

Description: In this paper, the advantages of shaping a non-conventional triple collocation-based calibration of a wave propagation model is pointed out. Illustrated through a case study in the Bagnoli-Coroglio Bay (central Tyrrhenian Sea, Italy), a multi-comparison between numerical data and direct measurements have been carried out. The nearshore wave propagation model output has been compared with measurements from an acoustic Doppler current profiler (ADCP) and an innovative low-cost drifter-derived GPS-based wave buoy located outside the bay. The triple collocation—buoy, ADCP and virtual numerical point—make possible an implicit validation between instrumentations and between instrumentation and numerical model. The procedure presented here advocates for an alternative “two-step” strategy. Indeed, the triple collocation technique has been used solely to provide a first “rough” calibration of one numerical domain in which the input open boundary has been placed, so that the main wave direction is orthogonally aligned. The need for a fast and sufficiently accurate estimation of wave model parameters (first step) and then an ensemble of five different offshore boundary orientations have been considered, referencing for a more detailed calibration to a short time series of a GPS-buoy installed in the study area (second step). Such a stage involves the introduction of an enhancement factor for the European Centre for Medium-Range Weather Forecasts (ECMWF) dataset, used as input for the model. Finally, validation of the final model’s predictions has been carried out by comparing ADCP measurements in the bay. Despite some limitations, the results reveal that the approach is promising and an excellent correlation can be found, especially in terms of significant wave height.

Description: Rainwater harvesting (RWH) for domestic uses is widely regarded as an economic and ecological solution in water conservation and storm management programs. This paper aims at evaluating long-term trends in 20-day cumulative rainfall periods per year in Poland, for assessing its impact on the design and operation conditions for RWH systems and resource availability. The time-series employed corresponds to a set of 50-year long time-series of rainfall (from 1970 to 2019) recorded at 19 synoptic meteorological stations scattered across Poland, one of the European countries with the lowest water availability index. The methods employed for assessing trends were the Mann–Kendall test (M–K) and the Sen’s slope estimator. Most of the datasets exhibit stationary behaviour during the 50-year long period, however, statistically significant downward trends were detected for precipitations in Wrocław and Opole. The findings of this study are valuable assets for integrated water management and sustainable planning in Poland.

Description: For reactive transport process in porous media, limited mixing and non-Fickian behavior are difficult to understand and predict. To explore the effects of anomalous diffusion and limited mixing, the column-based experiments of bimolecular reactive migration were performed and simulated by the CTRW-FEM model (continuous time random walk-finite element method). Simulated parameters were calibrated and the correlation coefficients between modeled and observed BTCs (breakthrough curves) were greater than 0.9, indicating that CTRW-FEM can solve over-prediction and tailing problems effectively. Porous media with coarser particle size show enhanced mixing and the non-Fickian behavior is not affected by particle size. β (a parameter of CTRW-FEM) and Da (Damköhler number) of CTRW-FEM under different Pe (Péclet number) values showed logarithmic linear relationship. Model sensitivity analysis of the CTRW-FEM model show that the peak concentration is most sensitive to the average pore velocity and the arriving peak time of peak concentration is most sensitive to β. These findings provide a theoretical basis for handling mixing and non-Fickian behavior patterns under actual environmental conditions.

Description: Adsorption has been regarded as one of the most efficient and economic methods for the removal of antibiotics from aqueous solutions. In this work, different graphene-based magnetic nanocomposites using a modified solvothermal method were synthesized and employed to remove sulfadiazine (SDZ) from water. The adsorption capacity of the optimal magnetic reduced graphene oxide (MrGO) was approximately 3.24 times that of pure Fe3O4. After five repeated adsorption cycles, the removal rate of SDZ (100 μg/L) by MrGO nanocomposites was still around 89.3%, which was only about a 3% decrease compared to that in the first cycle. Mechanism investigations showed that both chemical and physical adsorption contributed to the removal of SDZ. The excellent adsorption performance and recyclability of MrGO nanocomposites could be attributed to their wonderful 3D interconnected petal-like structures. The MrGO with SDZ could be easily recollected by magnetic separation. The MrGO also exhibited excellent adsorption performance in the purification of real polluted water.

Description: The concentration of chemical and biological parameters in the ecotone of the surface microlayer (SML) occurring between the hydrosphere and the atmosphere of urban water bodies was investigated. Parallel, sub-surface water (SUB) analyses were carried out to compare the SML properties with the water column. The concentrations of trace metals, macronutrients, nutrients, chlorophyll a, pheophytin, abundance and biomass of phytoplankton and the number of heterotrophic bacteria in both studied layers were analyzed. Each of the studied groups of chemical parameters was characterized by specific properties of accumulation. Trace metals occurring in concentrations below 1 ppm, such as Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Zn and metalloid As, were accumulated to a higher degree in SML than in SUB. Macroelement concentrations, with the exception of Mg, were lower in the SML compared to the SUB. Nutrients, autotrophic and heterotrophic microorganisms occurred in the SML to a higher degree than in the SUB. Bacillariophyceae dominated the analyzed water bodies, which are typical for the spring period, as well as Chrysophyceae, Chlorophyceae, Dinophyceae and Euglenophyceae. Cyanobacteria dominated in one of the ponds. The abundance of individual phytoplankton groups was significantly correlated with Ca, K, Na, P-org, SO42−, F−, Al and Sr.

Description: Agricultural reservoirs play such a central role in supplying water to rural areas that it is essential to properly estimate the design flood for agricultural reservoirs under climate change. The objective of this study was to estimate the inflow design flood interval using a non-parametric resampling technique for agricultural reservoirs under climate change. This study suggested an alternative method to point estimation using insufficient past data by providing the interval of the inflow design flood under the representative concentration pathway. To estimate the interval of the inflow design flood, we employed the bootstrap technique, which estimated the confidence interval corresponding to the 95% confidence level. This study covered a spatial range of 30 agricultural reservoirs in South Korea and a temporal range of past and three future representative periods: the base period (2015s: 1986–2015) and future periods (2040s: 2011–2040, 2070s: 2041–2070, 2100s: 2071–2100). We analyzed the results of a 200-year return period and 24-hour duration as a representative case. For the 97.5th bias-corrected and accelerated percentile value, the overall inflow design floods were larger than the base period value (2015s) with the safety factor applied. The northern and midwestern regions of South Korea showed relatively greater changes than the southeastern region. Some agricultural reservoirs showed a decrease in the design flood during the 2040s but generally increased after the 2070s. Through the non-parametric resampling technique, the interval estimation was provided considering the uncertainty of the inflow design flood. By presenting the results for three periods, we can provide policymakers with information to select according to the target period. The findings may provide an essential step in replacing a safety factor used for determining the design flood of agricultural reservoirs with the confidence interval calculated in accordance with statistical characteristics.

Description: Floodplain wetlands are of great importance in the entire river and floodplain ecosystems. Understanding the hydrological processes of floodplain wetlands is fundamental to study the changes in wetlands caused by climate change and human activities. In this study, floodplain wetlands along the middle reach of the Yellow River were selected as a study area. The hydrological processes and the interactions between the river and the underlying aquifer were investigated by combining remote sensing, hydraulic monitoring, and numerical modeling. Wetland areas from 2014 to 2019 were extracted from Landsat 8 remote sensing images, and their correlation with the river runoff was analyzed. The results indicate that the river flow had a limited impact on the wetland size and so did groundwater levels, due to the strong reliance of wetland vegetation on water levels. Based on hydrological and hydrogeological conditions, a surface water–groundwater coupled numerical model was established. The comparison and correlation analysis between the monitored groundwater head and the simulated river stage also show that river flow did not play a first-order role in controlling the groundwater levels of wetlands in the study area. The simulation results also suggest that it is the regional groundwater flow that mainly sustains shallow groundwater of floodplain wetlands in the study area. The floodplain wetland of the study area was dynamic zones between the regional groundwater and river, the contrasting pattern of hydrological regimes on both banks of the Yellow River was due to a combination of regional groundwater flow and topography.

Description: Freshwater organisms are facing threats from various natural and anthropogenic disturbances. Using data sampled on a nationwide scale from streams in South Korea, we identified the crucial environmental factors influencing the distribution and abundance of freshwater gastropods. We used nonmetric multidimensional scaling and the random forest model to evaluate the relationships between environmental factors and gastropod assemblages. Among the 30 recorded species, two invasive gastropod species (Pomacea canaliculata and Physa acuta) have enlarged their distribution (10.4% and 57.3% frequency of occurrence, respectively), and were found to be widespread in streams and rivers. Our results revealed that the most influential factor in the distribution of gastropod assemblages was the ratio of cobble (%) in the substrate composition, although meteorological and physiographical factors were also important. However, the main environmental factors influencing species distribution varied among species according to habitat preference and environmental tolerance. Additionally, anthropogenic disturbance caused a decrease in the distribution of endemic species and an increase in the spatial distribution of invasive species. Finally, the results of the present study provide baseline information for planning successful strategies to maintain and conserve gastropod diversity when facing anthropogenic disturbance, as well as understanding the factors associated with the establishment of invasive species.

Description: Salento peninsula (Southern Italy) hosts a coastal carbonate and karst aquifer. The semi-arid climate is favourable to human settlement and the development of tourism and agricultural activities, which involve high water demand and groundwater exploitation rates, in turn causing groundwater depletion and salinization. In the last decades these issues worsened because of the increased frequency of droughts, which emerges from the analysis of Standardized Precipitation Index (SPI), calculated during 1949–2011 on the base of monthly precipitation. Groundwater level series and chloride concentrations, collected over the extreme drought period 1989–1990, allow a qualitative assessment of groundwater behaviour, highlighting the concurrent groundwater drought and salinization.

Description: Groundwater from karst circulation systems of Central Italy were sampled and analyzed, in 2018, for delineating a preliminary, general geochemical framework of their relationship with neotectonics, in an area characterized by a frequent and often destructive seismicity. We determined field physical-chemical parameters, concentrations of main dissolved ions and gases and isotopic composition of water (δ18O, δD) and total dissolved inorganic carbon (δ13C TDIC). We discriminated between “normal” hydro-karst systems and multi-component aquifers, composed of meteoric groundwater that have also interacted with rocks of different lithological nature and/or deep fluids. These multicomponent aquifers are of potential interest in the monitoring of neotectonics activity, because changes in the stress field associated with the preparatory phase of an earthquake may affect the permeability of rocks, in turn causing variation of their chemical-isotopic character. The geographical distribution of these aquifers seems to be controlled by tectonics. In fact, the Olevano–Antrodoco–Sibillini thrust separates the more anomalous sites, located westwards of it, from the groundwater bodies at its eastern side, showing a more typical karst character.

Description: Nutrient losses from agricultural fields have long been a matter of concern worldwide due to the ecological disturbance this can cause to surface waters downstream. In this paper a new design concept, which pairs a surface-flow constructed wetland (SFW) with a woodchip bioreactor (WB), was tested in relation to its capacity to reduce both nitrogen (N) and phosphorus (P) loads from agricultural tile drainage water. A nutrient mass balance and a comparative analysis were carried out together with statistical regressions in order to evaluate the performance of four SFW+WBs under different catchment conditions. We found marked variations between the systems in regard to hydraulic loading rate (0.0 to 5.0 m/day) and hydraulic retention time (1 to 87 days). The paired system worked as nutrient sinks throughout the study period. Total N and total P removal efficiencies varied from 8% to 51% and from 0% to 80%, respectively. The results support the use of the new design concept for nutrient removal from tile-drained agricultural catchments in Denmark as part of national management plans, with the added advantage that smaller areas are needed for construction (0.1% to 0.2% of the catchment area) in comparison to standalone and currently used SCWs (~1%).