Geomorphological aspects of the transformation of a large plain reservoir (according to measurements at the Krasnodar reservoir)

The article considers the results of the analysis and generalization of the materials of bathymetric surveys of the Krasnodar reservoir in 2005, 2016 and 2021. The Krasnodar reservoir occupies a key position in the Kuban reclamation complex, so its transformations caused by siltation cannot be underestimated. Special attention is paid to the geomorphological aspects of the transformation of the reservoir bed in the process of siltation, which directly affects the morphometric characteristics of the reservoir. According to a series of bathymetric surveys, digital elevation models of the basin and maps reflecting the distribution of bottom sediments and the processes of morpholithogenesis of the bed were constructed. During the period 2005–2021, the volume of sediment accumulation in the main reservoir, excluding the separated Tcshikskoe reservoir and deltaic sediments of the dividing bridge, amounted to 127 million m³. The greatest contribution to geomorphological transformations is made by fluvial processes, with the participation of which deltas of rivers flowing into the reservoir (Kuban, Belaya, Pshish, etc.) and estuarine avandeltas are formed. So, for 2016–2021. within the mouth of the Kuban seashore, the volume of sediments amounted to 9.36 million m³ or 38 % of the total volume of the siltation body in the reservoir, and the increment of the siltation layer over 5 years reached 2–3 m or more. Within the zone of variable backwater in the open part of the water area, bottom sediments are distributed relatively evenly with an increment of the sediment layer over 5 years of 0.01–0.4 m. The lowest rates of sediment layer increment were observed in the dead volume zone—less than 2 cm per year. During the study period, a decrease in the average annual volume of situation was recorded, which presumably indicates a gradual attenuation of the siltation process as the volume of the reservoir decreases.