Abstract: The major share of available fresh water in India, almost 80 percent, is used for agricultural irrigation. The country is already facing water scarcity. Therefore, it is necessary to utilize and conserve water used for irrigation effectively so as to improve water productivity and achieve the objective of ‘more crop per drop’. Farmers are using seeds, fertilizers and pesticides in measured quantity but not the water which is an important and scarce resource. The main reason for this is lack of simple farmer’s friendly irrigation scheduling tools. In this context, adoption of scientific irrigation scheduling techniques can assist the farmers in effective utilization of the available water resource. In this study efforts were made to develop simple irrigation scheduling method and tool to optimize water use. A study carried out on a farmer’s field for irrigation of wheat crop for two years showed that there was 18 to 22 percent saving of water and 25 to 30 percent increase in water use efficiency in terms of yield per unit of water if measured quantity of water is supplied based on evaporative demand of crop as against traditional method of adhoc supply. In this study, crop irrigation requirement based on Cumulative Pan Evaporation (CPE) is used to apply irrigation water (IW). In addition to this IoT-based soil moisture sensor is installed in the root zone of the crop to monitor and give alert for scheduling irrigation at management allowable depletion (MAD) of soil moisture to avoid water stress. Based on the study, Data driven irrigation scheduling APP is developed which is easy to use by the farmers.

Abstract: Dili, the capital of Timor-Leste, is experiencing increasing freshwater demand driven by population and economic growth. It totally relies on groundwater from the Dili Intergranular Aquifer System for supply. There is very little conceptual understanding of the system and little-to-no monitoring data. Understanding the hydrostratigraphy, recharge and surface-groundwater interactions, groundwater levels and abstractions are essential for sustainable groundwater use and management. These are the aims of this study, and a numerical model was created with such purpose. The model included scenarios to assess how the aquifer could react to future increases in groundwater abstraction. Trial and error calibrated the steady-state model, and a comparison of simulated results with observed heads revealed good agreement (RMS <10%). Transient scenario simulations demonstrate that recharge (direct, river infiltration, and mountain-block processes) is a key component of the water balance and plays a critical role in aquifer sustainability under increasing groundwater abstraction. Aquifer storage is projected to decrease significantly by 2054, with the magnitude depending on the range of recharge and abstraction rates considered. The model improves conceptual hydrogeological knowledge of the basin, highlights future work needed, and provides a robust basis for sustainable groundwater management and water risk mitigation in Dili.

Abstract: Groundwater quantification is essential for sustainable water resources management, yet it is often hampered by limited data availability and difficulties in measuring spring discharges. This study investigates three carbonate aquifers in Central Italy’s Abruzzo region: the Genzana–Greco, Morrone, and Marsicano mountains. The aim is to resolve uncertainties in spring attribution, and groundwater flow patterns using isotopic analyses combined with field surveys. The Genzana–Greco aquifer was examined to clarify the sources of the Acquachiara spring and the previously unreported Germina spring, assessing whether recharge occurs locally or from the carbonate massif. In the Morrone mountain aquifer, discharge gains along the Pescara River through the Gole di Popoli were quantified, and spring isotopic compositions were compared to the main basal spring Giardino to better define groundwater contributions. For the Marsicano mountain aquifer, the role of Lake Scanno in feeding the Villalago springs was investigated through isotopic analysis of inflows, downstream springs, and basal aquifer discharge points to constrain the hydrogeological water budget. Overall, the integration of isotopic tracers with hydrological measurements allowed a more precise characterization of aquifer recharge areas, mean residence times, and groundwater flow paths, improving the understanding of regional water resources in a complex carbonate setting.

Abstract: Potato-Chips Processing (PCP) industry generates huge amount of wastewater heavily polluted with organic matter and nutrients. Current treatment technology of PCP wastewater uses dissolved air flotation (DAF) and activated sludge sequential batch reactor (SBR); both consumes large amount of chemicals and represents energy-intensive system. This study explores algal photobioreactor (APBR) as a sustainable system for PCP wastewater treatment, nutrients recovery and algal biomass production. Raw wastewater, anaerobically pre-treated effluent and DAF-SBR effluent were used in 1st, 2nd and 3rd APBR. Three feed volumes from each source (150, 200 and 500 ml for 1st and 2nd APBR and 200, 400 and 600 ml for 3rd APBR) to a fixed volume of algal seed (200 ml) were tested to select optimal feed volume and harvest time using 1-L APBR . System performance and impact of water characteristics on quantity and quality of algal biomass were explored at preselected feed volume and harvest time in 6-L APBRs. All experiments were carried out in growth chamber with continuous light (148.75 μmol.m-2.S-1). Results showed that 150 ml is the optimal feed volume for 1st and 2nd APBR at 10 days and 9 days growth cycle. 400 ml and 8 days were the optimal feed volume and growth cycle for 3rd APBR. Average dry biomass yields at preselected optimal conditions were 65.3±11.4, 69.9±12.0 and 100.6±11.7 mg/l.d in the 1st, 2nd and 3rd APBR. The 1st APBR achieved % removal of 99.2±0.4, 98.7±0.8, 89.1±4.3 and 97.5±1.4 for turbidity, COD, TKN and TP on average. Corresponding % removal in the 2nd APBR are 97.6±2.6, 91.6±7.5, 93.6±4.5 and 96.1±1.4 while the 3rd APBR achieved 98.5, 76.2 and 97.0. Additionally, the results of protein content and amino acids profile indicate significant impacts of feed water quality on the two parameters. The protein content was 30.64, 32.53 and 35.65% in the 1st, 2nd and 3rd APBR respectively. Similarly, the amino acids profile indicated significant higher % of the amino acids in the 3rd reactor compared with the 1st and 2nd one.

Abstract: Traditional wastewater treatment plants are not generally designed to handle degradation of pharmaceuti-cal-based contaminants, nor do such plants generally incorporate processes that enable complete elimina-tion of pharmaceutical residues. Therefore, pharmaceutical metabolites can be found in groundwater, sur-face water, and even drinking water in low concentrations. Advanced Oxidation Processes (AOPs) are promising to avoid the contamination of agricultural land and aquifers. Here, we focus specifically on the use of photocatalytic degradation processes via titanium dioxide (TiO2) nanoparticles as a photocatalyst, as-sisted by UV radiation and enhanced by H2O2. This degradation approach may allow the degradation of pharmaceutical compounds, such as acetaminophen (ACE), in municipal water treatment plants in which a tertiary treatment phase is suitable. We employ a batch, water-cooled jacketed reactor equipped with a UV lamp containing a TiO2 nanoparticle suspension for the degradation of ACE. We identify favorable condi-tions for contaminant degradation (~63%) at low concentrations of both ACE and titanium dioxide after 90 minutes of treatment. Several combinations of potential AOPs approaches were compared (e.g., UV-C only, UV-C/H2O2, UV-C/H2O2/TiO2 and H2O2 alone). In general, the combined action of the techniques leads to a better degradation of the contaminant. The results suggest AOPs are promising candidates for removal of pharmaceutical metabolites from wastewater effluents.

Abstract: This article presents results of hydrological research on the Ruda River, which is the largest tributary of the Cetina River situated in the Dinaric karst of Croatia. Hydrology of this river has been substantially altered after the construction of the Orlovac Hydropower Plant (HP) and the Buško Blato reservoir in 1973. The main aim of research was generation of new knowledge about the hydrological functioning of the river, where the focus was on the discharge and water temperature regimes that experienced most severe alterations. The methodology is based on classical hydrological, statistical, and time series analysis methods adapted to particularities of study area and available data. Daily and hourly time series of air temperature, precipitation, water temperature, and discharge are analyzed to find trends, change points, inter-annual, seasonal, and sub-daily variations, durations, time shifts, and linear dependencies. The obtained results provide information on effects of climate change, duration of diffuse, conduit, and mixed flow, importance of groundwater exchange, retention times, heat transfer times, referent water temperatures. It determined the role of operational mode of the Orlovac HP in the discharge from spring, inter-annual and sub-annual redistribution of water, hydropeaking, and thermopeaking. The obtained information defines the present state of Ruda River hydrology and illustrates alterations.

Abstract: Seasonal tropical wetlands such as the Brazilian Pantanal are increasingly threatened by climate change and extreme events, creating a need for robust monitoring tools that capture hydrological dynamics at high spatial and temporal resolution. This study evaluates Sentinel-1 Synthetic Aperture Radar (SAR) imagery to map and monitor flooding within the Ramsar-designated SESC Pantanal Reserve from 2017 to 2020. Ground Range Detected (GRD) VV-polarized scenes were pre-processed with radio-metric terrain normalization and speckle filtering (Lee filter, 5×5 window) to improve separability of water and non-water surfaces. Flooded areas were first extracted using Otsu’s histogram thresholding and validated with high-resolution optical imagery (PlanetScope and Landsat-8). A supervised Random Forest classifier then refined land-cover discrimination into three classes (open water/flood, open land/vegetation, and others), with temporal consistency supported by Cuiabá River hydrological data. Results indicate strong interannual variability in flood extent, with March 2017 inun-dating 34.7% of the reserve compared with 0.75% in March 2020, and peak inundation in April 2017 (79.9%). Overall, Sentinel-1 SAR effectively delineated open water and flooded vegetation under persistent cloud cover, highlighting its value for comple-menting existing products (e.g., MapBiomas), strengthening wetland management, and supporting scalable flood monitoring in other tropical, flood-prone Ramsar sites.

Abstract: Urban flood modelling in infrastructure-dense and heavily modified catchments requires enhanced process realism, operational applicability, robust diagnostic and scenario-based evaluation to reliably capture complex system interactions and support decision-making under extreme and failure conditions. This study employs a TELEMAC-2D rain-on-grid approach to simulate pluvial flood dynamics in two urban sub-catchments of the Emscher River (North Rhine-Westphalia, Germany). A stepwise model development and calibration workflow is implemented, combining and adjustments of land-use-based roughness, re-finement of SCS Curve Numbers, and the progressive integration of key hydraulic and op-erational components, including culverts, bridges, retention basins, and pumping stations. Model performance is evaluated based on hydrograph shape and volume, peak discharge and its timing, and inundation extent, with a specific focus on the relative contributions of (i) surface parameter calibration (friction coefficient-Manning’s n and run-off- Curve Numbers), (ii) explicit representation of hydraulic structures, and (iii) operational control rules under varying rainfall scenarios and antecedent moisture conditions (AMC). The analysis tests the hypothesis that structural and operational realism can contribute as much as traditional surface calibration to improve model performance and that their effec-tiveness is strongly influenced by prior wetness. Results shows that including retention basins and pumping stations along with operational rules significantly improves agree-ment with observed discharge. It shows systematic sensitivity and improvements across AMC scenarios with NSE values from -0.129 to +0.77, RMSE from 3.380 to 1.52 m³ s⁻¹, peak discharge errors from −6.20 to −0.49 m³ s⁻¹, and volume bias from −0.67 to +0.04. This shows that even with careful calibration of surface parameters (e.g., roughness and runoff coefficients), models that exclude infrastructure (e.g., pumps and retention basins) fail to accurately reproduce peak flows and recession behaviour. A targeted routing-focused cali-bration (R4) further reduced the remaining peak timing mismatch under saturated condi-tions, but introduced increased volume bias, indicating that residual discrepancies are primarily linked to simplified representation of fast urban conveyance pathways rather than surface parameterisation alone. Flood response is not determined by rainfall alone. Initial wetness and how infrastructure is operated can strongly and unpredictably change flood behaviour. Overall, the findings emphasise that for a complex and engineered urban environment, reliable urban flood simulations requires the combined consideration of hydrodynamic processes, hydrological initial conditions, and operational behaviour. The study provides practical guidance on the limits of calibration-only approaches and identifies when explicit representation of infra-structure and operational processes is essential for robust modelling.

Abstract: Wastewater treatment plants (WWTPs) are increasingly considered a key and importante infrastructure for environmental protection and combating climate change in regions suffering from severe water scarcity. This work aims to provide a comprehensive and integrated evaluation of the performance of WWTPs in arid and hyperarid contexts, based on two representative experiences in the Algerian Sahara. The evaluation is based on an analysis of treatment performance (COD, BOD₅, TSS), operational stability, and the agricultural suitability of the wastewater (electrical conductivity, SAR, RSC), in addition to the indirect effects on groundwater protection. The results show high and stable organic matter removal rates (&gt;85-90%), demonstrating the effectiveness of biological processes under harsh and hostile climatic conditions. Despite this, residual salinity and sodium carbonate remain the two main factors limiting the extent of long-term agricultural reuse, even with effective treatment. The international comparative analysis highlights the systemic nature of this separation in hyperarid environments and seeks to confirm the need to consider wastewater treatment plants as truly integrated environmental barriers.

Abstract: Nowadays, most water meters are mechanical and intended to be installed on pipes completely filled with water. But the pipelines of a water supply network may contain air, which poses a metrological problem: if this air flows through the domestic intakes, it can propel the moving part of meters, resulting in an overestimation of water consumption. Of how much? There is a surprising lack of field data on this topic. So, the case of one house is reported: it is located at the top of a steep and sparsely occupied street, with water typically supplied for a few hours per day. The house's meter (multi-jet) was estimating a huge and erratic consumption: several times more than what would be normally expected on average, and with some daily peaks exceeding the built storage capacity (underground cistern plus roof tank). After one year of monitoring, including the installation of a few devices, it is concluded that: (1) the house's meter was affected by air in the water supply network (most likely for different reasons, of which three are discussed); (2) a small air-release valve installed just upstream from the meter did not solve the problem; (3) another mechanical meter (single-jet) installed just downstream was also affected by air (although to a lesser extent), and (4) reliable estimates of water consumption were finally obtained with an ultrasonic meter installed at the domestic intake (and with a mechanical meter installed at the roof tank's outlet). Thus, the case reported emphasizes the need to study more how air in pipelines affects mechanical water meters, and to sometimes consider alternatives for measuring domestic water consumption.

Abstract: To address the feasible issues in water treatment facilities such as low particle removal and overuse of chemical in flocculation-sedimentation treatment of complex sediment-laden particles in snowmelt and high-intensity rainfall water, this research presents a new multi-layered separation tank. Combining a multi-layer structural design and a synergistic enhancement mechanism flocculation-centrifugation it is possible to engineer the tank to achieve a great improvement in the coexistence. This study methodically examines the impact of the agitator speed, agitator height and the number of blades on the flow field qualities and the effectiveness of the agitator in removing particles in the multi-layer separation tank. Computational fluid dynamics (CFD) simulation validation, comparison with hydro-calculations and laboratory experiments are used in a combined method. Findings show that there is strong agreement between numerical representation and experimental values in determining the optimal conditions of operation and the exact rate of dosage of polyaluminum chloride (PAC) and polyacrylamide (PAM). At these optimised conditions, the system magnetises at a 75.25 percent removal rate of particles whose size ranges are 20–50 μm and turbidity of the effluent decreases to 10.6 NTU in 30 minutes of settling time. The proposed technology is more efficient than conventional coagulation processes in that effluent turbidity is reduced by 22.1% with same dosages of chemical additive indicating a higher performance of the proposed technology.

Abstract: Water is a vital resource for the universe's survival of both flora and fauna, broadly referred to as an elixir of life. However, high population growth, encroachment of catchment areas, and climate change have rendered water resources scarce, leading to reliance on alternative groundwater sources to supplement the less freshwater sources for domestic, agricultural, and industrial use. Groundwater is considered a reliable source of uncontaminated water for various uses in rural and urban settings, especially for drinking. However, the uncertain potability of groundwater sources such as springs and boreholes remains a great concern, particularly when used untreated for human consumption, posing serious human health threats. This study assessed the physico-chemical quality using selected groundwater parameters from a natural spring (Mwonyo) at Nkubu, Nkuene ward, Meru County, Kenya, to determine its suitability for human consumption. A systematic sampling design was employed and a total of four water samples were collected in triplets of 500 ml water bottles and analyzed in the laboratory following standard analytical procedures using specific meters and Atomic Absorption Spectrophotometer (AAS). Examined parameters included; color, taste, electrical conductivity, dissolved oxygen, pH, temperature, and turbidity, as well as concentrations of phosphate, fluoride, ammonia, nitrite, and nitrate ions. The results were compared with the maximum contamination levels (MCLs) by the Kenya Bureau of Standards (KEBs) and World Health Organization (WHO) guidelines for drinking water quality to determine the suitability of the sampled water for drinking purposes. The study findings showed that the sampled water exceeded permissible limits for several physico-chemical parameters, including low pH (6.36), high electrical conductivity (2380 μS/cm), turbidity (16.30 NTU), and elevated concentrations of phosphate (0.12 mg/L), ammonia (0.86 mg/L), and fluoride (122.8 mg/L), indicating potential contamination originating from natural and anthropogenic sources. The study recommends further investigation and appropriate water treatment interventions to ensure public safety. While some other parameters were within the permissible levels e.g., temperature (28.3°C), dissolved oxygen (4.2 mg/L), and nitrates (0.57 mg/L), the overall water quality was deemed unsuitable for drinking without undergoing treatment. These parameters might be influenced by the geological makeup of the region and seasonality. This study thus recommends further investigation and appropriate water treatment interventions to ensure human health safety.

Abstract: Agriculture has to be drastically assisted by the new promising technological advancements to alleviate the extremes in water demand and/or water waste. In this regard, this work showcases how soil moisture instruments can be combined with low-end microcontrollers, energy efficient communication protocols, single board computers, flow and pressure sensors, and in-purpose actuators to form a synergistic platform able to generate and study a diverse set of realistic irrigation scenarios, thus paving the way for the creation of intelligent models intercepting water misuse events and/or irrigation failures. Two drip irrigation points were setup, each having a TEROS 12 and a TEROS 10 instrument placed at different depths, while a prototype water flow/pressure control and report system was developed. All modules were sending data in real-time, via LoRa, to a central node implemented using a Raspberry Pi, for further processing and for making them widely available via common network infrastructures, also provisioning for remote scenario invocation. The exact steps being necessary, for the specific hardware and software components to be combined into a functioning whole, are clearly explained, thus allowing other teams of researchers and/or university educators worldwide to be inspired and benefited from platform replication.

Abstract: Aerobic granular sludge (AGS) represents a promising alternative to the conventional activated sludge process for wastewater treatment, owing to its advantages in reducing land area requirements, operational costs, and carbon footprint. With the increasing global implementation of full-scale AGS systems, recent research has increasingly focused on the recovery of valuable resources from waste AGS. AGS has been identified as an effective carrier for a variety of valuable substances, including alginate-like exopolymers, polyhydroxyalkanoates, phosphorus, tryptophan, xanthan, curdlan, and cellulose. This paper aims to provide a comprehensive review of the recovery potential, extraction methodologies and current state of knowledge regarding each of these materials. To improve economic viability, future research should prioritize the development of strategies for the sequential recovery of multiple resources from AGS. Furthermore, integrating AGS with other emerging technologies, such as microalgal treatment and partial nitritation/anammox process, may enhance the reclamation of organic carbon from wastewater.

Abstract: The study evaluated the drinking water quality of Rouxville (RX) in Mohokare Local Municipality in the Free State, using chemical, physical, and microbiological parameters in comparison with South African National Standard 241 (SANS 241:2015). Drinking water samples were collected monthly from 5 sample sites, including the water treatment plant (WTP) and four end-user points, over a period of three years (2021–2023). Microbiological parameters revealed persistent non-compliance, with total coliforms and Escherichia coli (E. coli) frequently exceeding recommended limits by SANS 241 at multiple sites. The highest total coliform concentration of 201 CFU was recorded at the Rouxville Water Treatment Plant during the third year (2023) of sampling, while E. coli reached a maximum of 11 CFU at an end-user point, indicating the presence of possible pathogens in the water system. Colour exceeded the recommended limit (15 Pt-Co mg/L) at all sampling sites, with the highest value of 133 Pt-Co mg/L recorded at Rolelethunya Library. Chemical parameters mostly complied with SANS 241 limits, elevated values of total alkalinity and aluminium were observed at certain sites, particularly during the third year (2023) of sampling. The Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI) was also used to determine the overall water quality of the sample sites. The findings revealed that several sample sites had non-compliant parameters. The CCME-WQI revealed that the drinking water quality of Rouxville was either in the marginal or fair category, indicating that the water quality may be occasionally or frequently threatened, posing public health risks. These findings highlight the urgent need to ensure regular maintenance of WTP and ensuring continuous microbial monitoring.

Abstract: In Mexico, more than 70% of water rights are allocated to agriculture, yet irrigation efficiency remains low, ranging from 40% to 60%. In arid regions of northwestern México and the southwestern United States, prolonged drought, rising temperatures, and elevated evapotranspiration intensify irrigation demand and accelerate depletion of shared transboundary groundwater aquifers, which represent the primary water source for agriculture and communities on both sides of the border. Continued overexploitation threatens the long-term viability of these interconnected systems, underscoring the urgent need for coordinated, binational strategies for sustainable groundwater management. This study presents the implementation of water-saving technologies to enhance irrigation efficiency in small farms within transboundary basins, using Smart Farming Technologies (SFT) and Climate-Smart Agriculture (CSA) approaches. A real-time digital platform was developed to collect soil and atmospheric data through sensors and weather stations connected via a LoRaWAN network. These data were used to estimate localized evapotranspiration and crop-specific water requirements for pecan orchards. By synchronizing irrigation with actual crop water demand, farmers significantly reduced groundwater pumping, energy consumption, and conveyance losses. After five years, water use declined by approximately 60% compared to traditional flood irrigation. Broad adoption of these tools can mitigate transboundary aquifer depletion, strengthen cross-border collaboration, and promote resilient, water-efficient agriculture under increasing climate stress.

Abstract: Climate change is increasingly affecting groundwater resources in the Carpathian Basin, and rising temperatures are expected to increase irrigation demand and pressure on aquifers; the Nyírség region in north-eastern Hungary, a hydraulically coherent recharge–discharge system, provides a suitable setting to investigate these impacts. We analysed multi-decadal groundwater levels from shallow monitoring wells (1970–2022) together with hydroclimate indicators derived from CHIRPS precipitation and ERA5-Land snow and temperature data (1981–2024). Using these inputs, we developed a MODFLOW groundwater flow model for the study area and calibrated it for representative drought and rainy periods, explicitly incorporating permitted withdrawals and estimates of illegal pumping, and applied scenario simulations to assess expected mid-century (2050) climate conditions and human-driven changes, including managed aquifer recharge options. The hydroclimate indicators show strong interannual precipitation variability alongside an overall warming and drying tendency and reduced snow storage. Scenario runs indicate declining shallow groundwater levels, with the largest decreases in higher-elevation areas, while increased pumping primarily intensifies local drawdown near major well fields. Model results suggest that direct subsurface injection is the most effective recharge approach, and water-budget analysis indicates that natural variability can drive subsurface flow changes much larger than those caused by water production, underscoring the need for integrated, long-term measures that include changes in water use.

Abstract: Recent laboratory experiments in an intermediate-scale Hele-Shaw cell, designed to emulate a coarse sand aquifer, demonstrate that calcite precipitation induced by mixing leads to the formation of a self-organized, heterogeneous porous medium. This medium is characterized by elongated carbonate structures and internal preferential flow channels aligned with the main flow direction. The resulting transport behavior exhibits strong anomalous features, as evidenced by breakthrough curves showing earlier solute arrival, a distinct double peak, and pronounced tailing. In this article, we investigate the relationship between the self-organized heterogeneous structure of the porous medium formed through mixing-induced precipitation and its impact on solute transport. To achieve this, we analyze the spatial variability of hydraulic conductivity by implementing different permeability scenarios in a random walk particle tracking model. These scenarios, derived from image analysis of the precipitated structures, range from simple representations to increasingly complex configurations. Our results highlight the importance of capturing two key features to effectively describe solute transport. First, delineating the total precipitated area is crucial for accurately representing flow diversion caused by permeability reduction, which explains the emergence of the double peak in solute concentrations. However, fully capturing both the double peak transition and tailing requires representing the internal structure of the high-precipitation zones within the precipitated area, as these characterize internal preferential flow channels.

Abstract: The hydropower plant together with its reservoir makes it possible to modify the natural flow regime. These changes can affect sediment transport dynamics and cause morpho-logical changes in the river. If the river is also used as a waterway, the operational scenar-io of the hydropower plant can have a significant impact on sediment deposition, thereby reducing its navigable depths and increasing the risk of vessel–riverbed collisions. In this study, a 2D hydrodynamic model of the Danube River downstream of the Gabčíkovo Hy-dropower Plant (GHP) in Slovakia was developed to evaluate the influence of operational scenarios on maintaining the required navigable depths and to determine the most suita-ble scenario in terms of fairway maintenance costs. The operational scenario of the GHP influences the amount of sediment deposited downstream of the plant. The volume of deposition in the critical ford was approximately 50% smaller under hydropeaking than under run-of-river operation. The increase in riverbed elevation during hydropeaking was 33% to 64% lower than under run-of-river operation. The study results indicate that this reach of Danube can remain navigable for a longer period without intervention (dredging), thanks to sufficient navigable depth maintained by erosion caused by hydropeaking, compared to run-of-river operation.

Abstract: Water quality is traditionally assessed using epidemiological, organoleptic, sanitary-toxicological, and radiation criteria. However, recently, increasing evidence points to the need to consider the structure of aqueous solutions, especially when used for therapeutic purposes. In this study, electrophysical methods were used to study aqueous solutions of sodium chloride of varying concentrations, drinking water, mineral water, and seawater. Patterns in the frequency and amplitude changes of a sinusoidal oscillator compared to distilled water were identified. Based on experimental data, the Ks coefficient is proposed for assessing the structure of drinking and mineral waters. It is defined as the ratio of the oscillation amplitude of the generator at its minimum frequency to the oscillation amplitude at its maximum frequency. A theoretical justification for the formation of the structural organisation of aqueous solutions depending on the concentration of dissolved salts is presented, taking into account the presence of associated and "free" water dipoles, as well as the formation of hydrate formations in a liquid medium. The need to account for intermolecular interaction forces involving water dipoles is emphasised.