NEW DATA ON SILTING OF THE KRASNODAR RESERVOIR

The paper analyzes spatial features and long-term dynamics of silting of the Krasnodar Reservoir, the key object of the entire reclamation system of the Krasnodar region with a 3.35 billion m3 annual limit of water intake for irrigation; the analysis is based on bathymetric survey data. Accurate and up-to-date estimates of siltation volumes and changes in the hydrometric characteristics of the reservoir are necessary to develop a correct long-term strategy for the consumption of water resources in the region. The reservoir has noticeably transformed since it was put into operation in 1973: it has divided into two independent reservoirs with the formation of an extensive barrier from sediments of the Kuban and Belaya rivers, and transformations are continuing. Bathymetric surveys of 2005, 2016, and 2021 were used to calculate the volumes of silting and hydrometric characteristics of the Krasnodar Reservoir. We have established that, taking into account the detached Tshchikskoe Reservoir and the bridge that has formed, over the period 2005–2021 the area of the mirror at a normal retaining level decreased from 382 to 224.2 km2, while the useful volume diminished from 1,606 to 1,270.4 million m3. Over the same period, the dead volume decreased from 192 to 135.1 million m3. During the period between the last bathymetric surveys, the volume of siltation amounted to 24.66 million m3; the average siltation rate for 2016–2021 (4.93 million m3) was found to be lower than the average value for 2005–2016 (6.86 million m3). With a background thickness of the silt layer of about 0.1 m for the period between the last surveys, its greatest values (1–3 m and more) were noted below the protruding Kuban delta at a section of more than 2 km long.