The Volga Reservoirs Soil Complex Spatial/temporal Transformation Communication 4. The role of Bank Protection in the Gorky Reservoir Bottom Sediments Formation

Intensity of the Gorky Reservoir banks and bottom sediments formation, as well as transformation of the main items of the suspended matter balance has been assessed on the basis of the monitoring data. Specific for the Volga reservoirs stage character of the banks and bottom sediments formation i.e. active phase over the first 30-40 years, then stabilization of geo/morphologic processes or their insignificant fluctuation, has been vindicated. Areas of the transformed soils and silted sediments have decreased and stabilized while the areas of coarsegrained alluviums have increased and now comprised half of the reservoir area. Sedimentation rate has decreased more than two times. Banks abrasion and bed erosion have 1.5 and 6 times decreased, respectively. This is connected with active bank protection. The water area has decrease by 82 km2 over the whole period of the reservoir exploitation. The role of bank protection in abrasion/erosion and sedimentation slowing-up, as well as impact of the runoff flows and the wing/wave regime on the banks and the bed, bottom sedimentation distribution and accumulation has been demonstrated. The process of silt and sediments accumulation in XX–XXI centuries both for the water body itself and its orographic zones has been reconstructed and forecasted.