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Studies on the effect of climate change on water resources in the 21st century indicate an increase in intense rainfall, an increase in the duration of the dry season, and a decrease in snowfall and, accordingly, snow cover. Based on data from the EURO-CORDEX project, the average multi-year monthly runoff amounts (Copernicus Climate Change Service, Climate Data Store, 2021) for each 30-year period and for the reference period for a rectangular area covering the territory of Bulgaria have been calculated. Climatic ...

Anthropogenic imprints, including hydromorphological pressure and illegal land use through unauthorised dumping and wastewater discharge, are various forms of human activity that often have lasting impacts on the natural environment. Despite this, integrating them into ecological assessments and water and natural resource management remains underexplored at the river basin scale. This study aims to investigate and analyse illegal dumping and pressures on freshwater resources in the Chepinska and Chepelarska River ...

This study investigates macroplastic pollution in the Ishem River, cited as one of the most polluted fluvial systems in Europe. The Ishem mouth is inside the marine protected areas (MPAs) Patok-Fushekuqe-Ishem and an important bird area (IBA). Also located near the Ishem Mouth is Cape Rodon, a nature reserve within the protected landscape/seascape area. Conducted within the framework of a joint scientific research agreement between Albania and Austria, this research aims to quantify macroplastic transport and eval...

This article examines the mineral composition of the waters of important rivers in the Adjara region: the Chvana, Adjaristkali, Merisi, and Chorokhi. These rivers are part of the Black Sea basin and are used for drinking water supply, domestic needs, and agriculture, while the Adjara region is an important tourist destination. The study was conducted using an IGPE-9820 plasma atomic emission spectrometer. The concentrations of aluminum, boron, barium, beryllium, arsenic, calcium, cadmium, cobalt, chromium, copper,...

This paper evaluates the potential of formation waters from mature oil fields of the Volga–Ural petroleum province as a source of valuable components. The study addresses the growing demand for strategic elements such as lithium, bromine, strontium, and rare earth elements, and the need to identify alternative resource bases. The research is based on a review and analysis of published geochemical data on produced waters from major oil fields, including Romashkinskoye, Orenburgskoye, and Arlanskoye. The concentra...

The Ciuc Basin is characterized by distinct climatic conditions that influence agricultural potential, hydrological balance, and regional climate resilience under ongoing climate change. This study analyzes temperature extremes and temporal variations of the Huglin Climate Index (HI), a widely used agro-climatic indicator for assessing viticultural and thermophilic crop suitability. The analysis is based on meteorological observations (temperature, relative humidity, and wind speed) from the national monitoring ne...

This study presents a comparative analysis of three methodologies for deriving intensity–duration–frequency (IDF) relationships of rainfall in Bulgaria: (i) the method embedded in the current regulation for sewerage system design, (ii) the methodology used for estimating maximum river discharge, and (iii) a recently proposed regionalization approach with site-specific IDF curves. The objective is to evaluate their accuracy and applicability under contemporary climatic conditions, with a focus on urban drainage...

Unmanned aerial vehicles (UAVs) are increasingly used in many industries and environmental monitoring systems. They play a particularly important role in the observation and research of difficult-to-access areas, such as watercourses, river basins, reservoirs, and wetlands. The ability to quickly measure basic physicochemical parameters of water, such as temperature, electrical conductivity, pH, and turbidity, is crucial for assessing the condition of the aquatic environment and initiating appropriate actions. The...

This study investigates the development of gravel-gelatin composites as pre-formed monolithic filter elements for borehole wells in unconsolidated sandy aquifers. The composites utilize food-grade gelatin as a natural, biodegradable, and low-cost binder to bond gravel particles into stable blocks, offering an alternative to conventional loose gravel packs that are labor-intensive to install and prone to placement inconsistencies. A systematic experimental approach was employed to optimize key manufacturing paramet...

Reliable stage-discharge rating curves are essential for flood forecasting and warning systems because they convert observed water levels into discharge estimates used for forecasting, warning thresholds, and operational decision-making [1]. This study evaluates the consistency of the stage-discharge rating curves and surveyed river cross-sections currently used in the Maritsa River flood warning system and develops recommendations for their revision. Four representative hydrometric stations along the Maritsa Rive...

Modern requirements for limiting the frequency of overflows in water bodies increasingly require an emphasis on increased control over sewer overflows and their operation. The requirements in the new Directive (EU) 2024/3019 of the European Parliament and of the Council of 27 November 2024 on urban wastewater treatment. One of the main requirements is to limit pollution from wastewater overflow during rainfall. This overflow should not be more than 2% of the annual load of individual parameters, accounting for bio...

Mining activities can significantly affect water resources by altering their chemical composition and promoting the mobilization of contaminants in aquatic systems. In this context, this study analyzed the hydrochemical and isotopic characteristics of hydric resources in a mining-impacted region of southern Ecuador in order to identify the main processes controlling water chemistry, determine the origin, and identify potential sources of contamination. Eighteen water samples were collected (10 surface water and 8 ...

Forest evapotranspiration is a key component of the water balance in mountain ecosystems and plays an important role in regulating regional hydrological processes. Accurate assessment of evapotranspiration, a key component of the water cycle, remains challenging due to the spatial and temporal variability of vegetation water use and the limitations of individual observation methods. The objective of this study is to assess forest evapotranspiration in the Rhodope Mountains (Bulgaria), simulated using the open sour...

The present study investigates water consumption patterns in 11 secondary and high school buildings in Sofia, Bulgaria, and evaluates the adequacy of the current regulatory requirements for this category of public buildings. Water consumption and pressure were monitored at one-minute intervals during two annual two-week measurement campaigns for each facility, resulting in a database covering 368 days. Water losses were identified through minimum night flow analysis and excluded from the assessment of effective wa...

The main objective of this study is to outline the spatial distribution of precipitation deficit at both monthly and annual scales by comparing precipitation data from two reference periods: 1961–1990 and 1991–2020. To achieve this goal, monthly and annual precipitation normals from 355 meteorological stations throughout the country are calculated in accordance with the World Meteorological Organization's standards. Data post-processing, statistical analysis and spatial interpolation are performed in the R env...

The volume of accessible groundwater in Latvia from a chosen aquifer is generally sufficient for a household or company to install a borehole with a flow rate of 10 m3/day or 100 m3/day. In this case, the main legal restrictions concern lowering the groundwater table to the minimum permissible level and the required water level reserve relative to the top of the well's filter column. Latvia is rich in groundwater water; for decision-makers to install a water intake well, it is usually sufficient to analyze data fr...

Global water use keeps rising and by 2050 may be about 30% higher than today. Growing pressure on freshwater resources and the high energy demand of conventional desalination encourage the search for alternatives. One option is freeze desalination, in which salt is separated as ice forms. This method requires far less energy than traditional techniques, and operating at low temperatures limits corrosion while allowing treatment of highly saline solutions. The technology is still under development because salt-reje...

Climate change and the increasing frequency of extreme rainfall events impose additional stress on urban drainage infrastructure and particularly on wastewater pumping stations operating within combined sewer systems. This study investigates the operational performance of an existing wastewater pumping station located in northeastern Bulgaria and subjected to significant hydraulic loading caused by permanent external inflows and stormwater runoff. The assessment combines field observations, SCADA-derived operation...

Taking Yuqiao Reservoir, a key drinking water source for Tianjin, as the research object, this study utilized Sentinel-2 MSI satellite data and synchronous in-situ measurements to investigate its eutrophication spatiotemporal changes from 2016 to 2023. Semi-empirical models based on the NDCI index were constructed for chlorophyll-a concentration inversion, while the QAA_RGB quasi-analytical algorithm was adopted for water transparency retrieval. The Comprehensive Trophic Level Index (TLI) was further calculated to...

The “Vacha” Regional Water Supply System represents a large-scale hydraulic infrastructure project designed to ensure long-term, climate-resilient drinking water supply for the city of Plovdiv and 28 surrounding settlements, with a planning horizon to 2070. The system is based on regulated surface water abstraction from the Dospat–Vacha cascade and integrates hydrological, hydraulic, and energy analyses to optimize resource utilization under changing climatic conditions. The study draws upon primary technica...

Rock glacier hydrology remains poorly constrained in marginal permafrost environments such as the Southern Carpathians. This study quantifies spatial variability by relating spring temperatures to elevation, aspect, lithology, and spring type, and temporal variability through diurnal and seasonal thermal amplitudes, to detect permafrost occurrence and assess its influence on alpine groundwater systems. Between 2020 and 2025, 62 alpine springs were systematically monitored in the highest sector of the Retezat Mount...

This article presents a reproducible workflow for deriving gridded total runoff threshold layers for Bulgaria and the adjacent regional domain. ERA5-Land hourly runoff for 1981-2025 was first converted from accumulated fields to hourly increments following the ERA5-Land accumulation convention [4][7]. Annual maxima were then derived for 1 h, 3 h, 6 h and 24 h totals, and fixed annual exceedance probability (AEP) return levels were estimated for 1% and 5%. The fine resolution product uses D(Q) downscaling: return l...

Sewerage, as a system designed to collect and discharge wastewater, also receives many other incidental objects, defined as sludge. Their removal from the network is usually carried out in the wastewater treatment plant (WWTP), where they are removed by known methods. However, this does not offer a solution for solid sludge, as it causes blockage in the network. Such a solution could be the modification of a well-known wastewater overflow into a new type of structure, known as a self-cleaning overflow. For this pu...

The aim of this work is twofold: to identify the dominant types of anthropogenic impact on SWQ in the Chepinska and Chepelarska River basins to localise the hot spots of pollution; and to obtain the main land cover units from Very High Resolution (VHR) Airbus Pléiades-1A and SPOT 6 imagery. The assessment of anthropogenic impacts on SWQ is based on an analysis of more than 10 physicochemical parameters, and the CCME WQI, WAWQI, and HPI indices were used. The results show different types of water pollution in the ...

The WatHer project – Water Heritage in European Rural Mediterranean: Re[dis]covering Water Heritage Systems to face climate challenges learning from our past – is funded by the European Union under the Interreg Euro-MED Programme and aims to promote climate change adaptation and disaster risk prevention through ecosystem-based approaches. Running from 2025 to 2029, the project is structured around eight pilot cases across the Mediterranean Basin, from Cyprus to Portugal, focusing on the study, restoration, and...