Climatic and hydrological conditions for the formation of vegetation cover in the drained Kakhovka reservoir’s territory

Abstract

Today, scientists focus on studying the state of natural vegetation cover in the drained Kakhovka reservoir’s territory. In this regard, our research aims to establish the patterns of plant growth and the stability of vegetation cover depending on the current climatic and hydrological conditions in the drained Kakhovka reservoir’s territory. The results were obtained and the conclusions were drawn in the course of conducting comprehensive field research, calibrating and decoding the satellite images of Sentinel 2 L2A in 2023–2024. At the end of September 2023, the area covered with plants was 52.4 thousand hectares. The winter-spring period of 2024 was characterized by favorable climatic conditions, which contributed to spring floods that submerged up to 70% of the drained reservoir’s territory. This led to substantial moisture accumulation in the bottom sediments, contributing to the rapid growth of plant biomass and active chlorophyll synthesis in leaves. At the end of September 2024, the vegetation cover area in the former reservoir’s territory increased twofold. The maximum area of the reservoir’s overgrown bed amounted to 135 thousand hectares in 2023–2024, including 48 thousand hectares with woody plants (willows and poplars); 87 thousand hectares were largely covered with marsh and meadow plants with shrub patches. The lack of precipitation and the abnormal increase in the air temperature in July to the historical maximum (+40.5–42.0 °С) for the examined area provoked an acceleration in evapotranspiration and depletion of moisture reserves in the drained reservoir’s territory. This caused a deterioration in plant growth, drying out, and partial degradation. It was found that at the end of September 2024, 75.3% of vegetation cover was characterized by varying degrees of growth disturbance. A significant disturbance was observed in 43.5% of the area. The premature plant drying caused a loss of good properties of chlorophyll synthesis in 72.8% of the area. Negative processes led to a decrease in the area of healthy vegetation by 26.3 thousand hectares. It was proved that an increase in the frequency of climatic anomalies and a reduction in the discharge volumes from the Dnipro hydroelectric power plant into the former Kakhovka reservoir’s territory is a cause of the complication of plant survival conditions.