Conditions of the Formation of Bottom Sediments in the Bratsk Reservoir

Abstract

Long-term investigations in the largest artificial pool (Bratsk Reservoir) have shown that the formation of bottom sediments is mainly governed by the geological structure of its shores and floor, the hydrodynamic regime of the reservoir, and the dynamics of the supply of sediment-forming material. The bed and shore zone of the reservoir are made up of Paleozoic, Mesozoic, and Cenozoic rocks. The shores composed of Quaternary alluvial and deluvial sediments are longest (2400 km). The principal indicator of the hydrodynamic regime of this basin is water level change that defines other parameters, such as waves and currents. The principal sediment-forming sources are river discharge and abrasion of coastal cliffs. The river discharge is a continuous, relatively stable (in time) geological process, whose action is dictated by climatic conditions of the region under consideration. The abrasion of coastal cliffs is a discrete event chiefly related to technological factor, i.e., changes in reservoir water level caused by the exploitation regime of the hydroelectric power plant.