The Krasnodar reservoir has undergone significant transformations during its operation since 1973. As a result of active delta formation of the Kuban and Belaya rivers, the reservoir was divided into two autonomous reservoirs, its area decreased by 35 %. To understand the mechanisms of transformation and the processes of siltation of the reservoir, it is necessary to establish the features of the dynamics of water masses. Based on the results of the ADCP survey carried out in July-August, 2016, the circulation of water masses in the reservoir was analyzed. The distance between survey lines during the survey was 100 m with a total length of 2518 km, the frequency of measurements was 0.28 m-1. The resulting array of data on the velocity vectors (18.6 million values) in combination with the resulting digital model of the reservoir basin was processed in GIS using geostatistical analysis tools. It has been established that the general dynamics of water masses is characterized by cyclonic circulation with a pronounced western runoff current along the right bank of the reservoir. The prevailing velocities of currents are 0.02 ... 0.05 m/s. With steady westerly winds, a shift of the main water jet to the south into the interior of the reservoir was recorded. In the vertical movement of water masses, ubiquitous downward currents were noted in the eastern part of the reservoir, caused by the influx of colder river waters.

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The article considers the long-term transformation of the Krasnodar valley reservoir, the largest in the North Caucasus. The main functions of the Krasnodar reservoir are irrigation of rice systems and flood protection of land in the Krasnodar reservoir region and the Republic of Adygea. According to topographic maps, Landsat satellite images and field observations (2016)(2017)(2018), four stages of transformation of the floodplain reservoir are identified. The selected stages are characterized by both natural causes (the transformation of the filling deltas into the extended deltas, etc.) and man-made causes (runoff diversions in the delta areas, etc.). The key factor of transformation is the formation of deltas of rivers flowing into the reservoir. Each of the selected stages, against the background of a gradual reduction in the area and volume of the reservoir, is characterized by the peculiarities of the formation of river deltas with the formation of genetically homogeneous sections of delta regions. During the period of operation of the reservoir, the delta of the main Kuban River moved up to 32.4 km and took away an area of 35.4 km 2 of the reservoir. During the formation of the deltas of the Kuban and Belaya rivers, a bridge was formed on the Krasnodar reservoir. The evolution of the delta regions led to the division of the reservoir into two autonomous reservoirs. The total area of the delta regions was 85.9 km 2 by 2018, i.e., 21% of the initial area of the reservoir. The transformation of the Krasnodar reservoir leads to a decrease in its regulated volume and gradual degradation.

Краснодарское водохранилище-крупнейший на Северном Кавказе искусственный водоём, имеющий противопаводковые и ирригационные функции. Располагается на территории Краснодарского края и Республики Адыгея. За период эксплуатации с 1973 года водохранилище испытало заметные преобразования, отразившиеся на трансформации чаши водоёма. По данным батиметрических съёмок 2004 ̶ 2005 годов и 2016 года выполнена оценка многолетних преобразований Краснодарского водохранилища в показателях его контуров, площади, ёмкости, изменений поверхности дна и других характеристик. Данные съёмок с последующим построением ЦМР позволили оценить динамику изменений морфометрических показателей Краснодарского водохранилища, произошедших в процессе его эксплуатации. В результате заиления водохранилище разделилось на два водоёма; бывшее Тщикское водохранилище оказалась изолированным от западной части Краснодарского водохранилища надводной перемычкой и превратилось в самостоятельный водоём. По данным батиметрических измерений установлено непрерывное уменьшение ёмкости и площади КЛЮЧЕВЫЕ СЛОВА: Краснодарское водохранилище, батиметрическая съёмка, цифровая модель рельефа, заиление, морфометрические характеристики, трансформация

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.