Browse

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...

When designing hydraulic, power and civil structures, special attention is paid to the study of the stress-strain state (SSS) of foundations from the soil environment. The operation of such structures often leads to changes in the SSS of the soil base, which can affect their stability. It is known that the SSS of soil bases significantly depends on the physical and mechanical properties of soils, hydrogeological conditions of the environment and the type of loads, in particular on the filtration of groundwater, ma...

Hydrological modelling has long been recognised as an essential tool for understanding and predicting water dynamics, particularly in regions where long-term observational data are limited. In Latvia, significant advancements have been made in the development of hydrological models, with the METQ model family becoming one of the most widely applied for the simulation of runoff and groundwater level regimes. Initially developed in the 1980s, METQ has been continuously refined to improve its predictive capabilities,...

Sulina channel is one of the three arms of the Danube, through which the river outflows into the Black Sea. At the same time, this is an important navigation waterway, since it is the main entrance from the Black Sea in the seventh Pan-European transportation corridor, represented by the Maine-Rhine-Danube navigation system. Hence, high navigation traffic is noticed, which was significantly increased in the last years. On the other hand, this area often faces severe weather conditions with high gradients in the en...

The paper presents a trend analysis in monthly precipitation, air temperature (average, minimum and maximum), air temperature range, potential evapotranspiration, drought and water balance over Romania using data from 156 weather stations. The recently released, freely available RoCliHom dataset has been used for this purpose. Trend analysis was conducted with the nonparametric Mann-Kendall test, as it allows a direct comparison with the vast majority of previous studies on climatic changes in Romania. Our results...

Industrial activities in the Jiu River basin, especially coal mining, have generated a significant impact on water quality over time, by releasing variable concentrations of heavy metals into the environment. This paper analyzes the trends of variation over time of the degree of heavy metal pollution in the Jiu River, considering the direct influence of the extractive industry in the area. The study is based on data collected from multiple water quality monitoring campaigns, covering an extended period, and aims t...

Babina Agricultural Enclosure is located in the northern sector of the Danube Delta near the Chilia branch, has undergone significant transformations over the decades. Originally designed as part of a large-scale aquaculture system, this area was later converted into agricultural land during the intensive land reclamation projects of the mid-20th century. However, following ecological rehabilitation programs initiated in the 1990s, Babina has regained its prominence as a important site within the Danube Delta Bios...

Water discharges, suspended load and hydrochemistry for 35 inflows of largest Caucasian Lake Sevan were measured 3 times in different hydrological seasons during 2024 and 2025. During summer most of small streams dried out while in winter a number of rivers were frozen into the bottom. The water discharges varied from 0.01 in summer to 8.02 m3/sec in spring. Large natural inflows are Argichi, Dzknaget, Gavaraget, Masrik rivers with water discharges in spring 8.0, 6.3, 4.5, 2.8 m3/sec correspondingly. By the end of...

This study explores the application of the Analytic Hierarchy Process (AHP) to identify groundwater retention potential within a 130 km- study area, leveraging high-precision LiDAR measurements and data from 150 wells. By integrating advanced geospatial technology with extensive field data, this approach offers a unique methodology for analyzing groundwater retention. AHP was employed to assess several key geographical factors, including the Topographic Position Index (TPI), slope, hydrographic network density, la...

The fish farming infrastructure in the Danube Delta, including the Popina Fish Farm Enclosure, has been significantly impacted by environmental factors, particularly due to climate change. Located in the northeastern part of the Danube Delta Biosphere Reserve, near the Chilia arm and the Black Sea, this enclosure once played an important role in aquaculture activities. Currently, the main threat to the area is the high water levels of the Chilia arm, which place constant pressure on the protective dykes, increasin...

Global climate change is intensifying hydrological variability and water scarcity, increasing the need for adaptive irrigation in small agricultural catchments. This study applies the analogue-river approach to evaluate the irrigation potential of the small lowland Kulpe River in northern Lithuania, which lacks discharge observations. Long-term flow data (2006 2021) from the hydrologically similar Daugyvene River were used to estimate the Kulpe s discharge parameters. The mean annual discharge was 1.18 m /s, corre...

The combination of Long Short-Term Memory (LSTM) neural networks, comprehensive trend analysis, and standardized pan evaporation measurements creates the capability for understanding and predicting regional evaporation dynamics in the context of climate change in this study. Based on the thorough examination of this study in the Slovak Republic's Vah river basin the K-means clustering analysis revealed three different patterns of evaporation behaviour (1.5-3.2 mm/day); the seasonal analysis revealed that peak evap...

The research was carried out to examine the influence of tributary inflows on the hydrochemical properties of the Svete River, which traverses intensive agricultural regions. Sixteen monitoring sites were selected along the main channel and at major tributary junctions. Water samples were collected monthly from surface layers (0 5 cm) over a one-year period, and concentrations of total nitrogen, total phosphorus, and selected metals were evaluated. A multi-parameter probe and an inductively coupled plasma optical ...

Floods are among the most common natural disasters in Slovakia, often causing extensive material damage and posing a serious threat to human lives. Given their frequency and potential negative consequences, it is essential for municipalities to have an effective flood risk management system in place. Municipal preparedness for flood management is a key factor in minimizing damage and involves various measures, such as the implementation of an early warning system, the development of evacuation plans, systematic pu...

This article analyzes the impact of flood events on fire brigade response activities concerning vehicles using alternative energy sources, with a particular focus on electric vehicles. Given the increasing number of electric vehicles and the observed rise in the frequency and intensity of floods attributed to climate change, the probability of these vehicles becoming submerged is increasing, posing specific challenges for fire brigades. The analysis focuses on the risks associated primarily with electric shock and...

This study assesses low-cost biochars produced from locally available agricultural residues, corn (BC-corn) and straw (BC-straw), as reactive sorbents for in situ groundwater remediation of vinyl chloride (VC). Biochars were obtained by slow pyrolysis under inert atmosphere and characterized by N2-BET at 77 K, CHNS, FTIR, XRD, and SEM/EDS. Sorption experiments were performed at 20+/-2 C in a synthetic aqueous matrix and in Danube alluvial groundwater containing elevated VC (11.6 to 17.8 ug/L) with typical backgrou...

Romania and the Republic of Moldova have a long-standing tradition of grape cultivation, one of the agricultural sectors that is highly sensitive to climate change. As the growth and development of grapevines are strongly dependent on the regional bioclimatic dynamics, this study presents projected climatic changes over Romania and the Republic of Moldova under three of the latest climate scenarios. The analysis focuses on ten biometeorological indices relevant to grapevine development (e.g. mean annual air temper...

Under climate change conditions, irrigation is a crucial factor for achieving sustainable yields, especially during the hot and dry summers. Irrigation possibilities and sustainability in terms of arable land determine the primary importance for the selected pilot area, as representative of agriculture in the Upper Thracian Lowland. The conditions in the region of Asenovgrad are suitable for cultivating perennial and spring crops, with irrigation water primarily supplied by the following dams: the 40 Izvora, Lenov...

According to Albania's geographical classification, the Mati River belongs to the North Central Highlands. From a climatic perspective, this region is characterized by significant variations in temperature and precipitation due to its diverse geographical altitudes, ranging from 1800 meters above sea level to 0 meters at the estuary. Hydrographically, the Mati River basin is distinguished by a dense network of water courses, particularly in its middle and lower sections, where ultrabasic formations dominate. Addit...

The Baltic Sea Region faces increasing pressure on water resources and ecosystems due to human activity, with nutrient rich treated wastewater discharges being a main cause of eutrophication. Combining algae-based nutrient removal with reclaimed wastewater reuse provides a sustainable solution to reduce pollution while allowing algal biomass recovery for further applications. Therefore, the aim of the study was to evaluate possibilities to use algae cultivation as a tool for nutrient removal from treated wastewate...

The river Iskar is the object of study. The development aims to update the technological scheme of the resource of surface water bodies for a new reference climatic period (1991-2020) and estimate the annual average values at the end of each water body. For the study, 20 gauging stations were used, which currently represent the NIMH monitoring network in the catchments of the streams on which the resource is based. In terms of area, the stations cover the whole catchment relatively evenly. For the study, the annua...

The presented scientific study analyzes the long-term regional trends in the intra-annual distribution of river flow in selected catchments in Kazakhstan: the Buktyrma River - Lesnaya Pristan village, Zhabay River - Atbasar city, Ulken-Kobda River - Kobda village, located in the basins of the Buktyrma, Esil and Zhaiyk rivers, respectively, from 1985 to 2022 years. The river basins were selected as regions characterized by different geographical features of flow formation, significantly affected by climate change. ...

Accurate forecasting of reservoir inflows based on historical data is essential for effective water resources planning and management. Water flow forecasting presents a major challenge due to the nonlinear, non-stationary, stochastic, and highly noisy nature of water flows in rivers and inflows into reservoirs. These complex characteristics hinder the modeling process and limit the effectiveness of conventional prediction methods, making it difficult to achieve high accuracy results. This study explores the use of...

Heavy metals as persistent pollutants of the aquatic ecosystems become a global issue of concern and are consistently increasing due to urbanization and industrialization. The aim of this study was to determine the heavy metals content in the water of the Mati River. Heavy metal levels were monitored during 2024 on four campaigns along the Mati River. Water samples were collected from five stations, covering the whole watershed area. Sample analyses were performed by Atomic Absorption Spectroscopy, (GF-AAS). This ...

Hydrological droughts are formed by different processes, but how strong and heterogeneous they are, leading to different hydrological droughts characteristics and propagation. Droughts have no distinct starting date, but different methods gives a course of action that may help to identify dry signals and possible, drought conditions for drought early warning and predict to some certain level the magnitude and water required for hydrological drought recovery. We choose hydrological drought indices system that are a...

Floods are worldwide among the most significant natural hazards. They can result from various causes, including severe storms, intense or prolonged rainfall, and landslides. The damage they cause is substantial, both economically and in terms of human life and wellbeing. Modern technologies, particularly artificial intelligence (AI), offer wide-ranging opportunities in this domain. AI can help forecast the weather, rainfall amounts and intensity, and other variables influencing flood occurrence. When integrated in...