The Phenomenon of Water Blooming in Reservoirs of Ukraine: Analysis of the Publications by Domestic

The degradation of water ecosystems in Ukraine due to large-scale human intervention has led to a deterioration in water quality, significantly affecting water availability for the population. Most natural water bodies are highly transformed, losing their ability for self-regulation and self-purification. The regulation of rivers through reservoirs and ponds has resulted in the formation of extensive shallow water areas with slow water exchange, intensifying water warming under the conditions of climate aridization. This, in turn, has led to the widespread occurrence of the water bloom phenomenon. This study examines the hydrological conditions of Ukrainian water bodies, focusing on the development of cyanobacterial blooms. Over 63,000 rivers exist in Ukraine, with a total length exceeding 206,000 km. Most are lowland rivers flowing toward the Black and Azov Seas, characterized by slow currents (0.2–0.5 m/s). The construction of numerous reservoirs, including the Dnieper cascade, has altered the hydrological regime, causing ecological imbalances such as increased sedimentation, reduced oxygen levels, and eutrophication. Cyanobacterial blooms in these artificial reservoirs are mainly caused by Microcystis, Aphanizomenon, and Anabaena species. The development of these algae depends on phosphate concentrations, water flow speed, and turbidity, with blooms most prevalent in slow-moving or stagnant waters. Using remote sensing methods, this research analyzed water bloom distribution across Ukraine. Findings indicate that bloom intensity correlates with water temperature, nutrient load, and hydrodynamic conditions. The highest bloom occurrence is observed in reservoirs with low flow rates and elevated summer temperatures exceeding 20°C, with peak development in July–August. Eutrophication is exacerbated by excessive nitrogen and phosphorus inputs, primarily from agricultural runoff and wastewater discharges. The study also reveals spatial variations in bloom intensity, with the highest levels in the Kremenchuk Reservoir and the lowest in the Kyiv Reservoir. The results underscore the urgent need for systematic monitoring of water bodies, especially during warm periods, to mitigate the adverse effects of eutrophication. The study highlights the importance of integrated water management strategies to control nutrient inputs and improve hydrological conditions. Future research should focus on developing measures to combat water blooms, incorporating both natural and technological solutions.