Geoecological aspects of assessing the consequences of Kakhovka Reservoir destruction

The article reveals one of the least studied aspects of the problem of determining the damage caused by the destruction of the Kakhovka hydroelectric power plant dam, namely, the removal of the reservoir's water mass downstream of the Dnipro River. In addition to the social and economic losses, this event had significant negative environmental consequences for vast areas both above and below the undermined dam, primarily related to changes in hydrological and hydrogeological conditions. In the article an important component of environmental assessment as definition of harm from the transfer of a number of pollutants that had accumulated in the bottom sediments of the Kakhovka Reservoir in the lower reaches of the Dnipro River, the Dnipro-Bug estuary and the northwestern part of the Black Sea is considered. The main tasks and components of the geochemical assessment of bottom sediments before the destruction of the dam, and the tools for their implementation are outlined. In particular, we focused on the necessity to take into account the distribution of various types of bottom sediments formed in the water area before dam destruction, their qualitative and quantitative characteristics, and the content of various types of pollutants in them. The rationale for employing sediment transport modeling, considering the physical properties of the sediments, as well as the hydro-physical and hydrochemical conditions of the Dnipro’s runoff formation in the initial weeks after the disaster, is substantiated for both the Kakhovka Reservoir area (resedimentation and removal processes) and the downstream aquatic zones (sedimentation processes). In practical terms, such studies will contribute to the creation of a factual basis for determining the impact of the Kakhovka disaster on benthic biocenoses, recreational and protected areas, as well as the development of relevant predictive indicators.