Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2023, Vol. 20, No. 2, pp. 205-215
On filling of the eastern part of the former Aral Sea due to water discharge through the Kokaral Dam from analysis of Aqua/Terra satellite images
1 Marine Hydrophysical Institute RAS, Sevastopol, Russia
Accepted: 28.03.2023
DOI: 10.21046/2070-7401-2023-20-2-205-215
By 2009, the bottom of the eastern part of the former Aral Sea (Eastern Aral Sea) was so exposed as a result of drying that it became possible to track from the satellite the movement of waters entering the Eastern Aral Sea due to water discharge from the Northern Aral Sea through the Kokaral Dam. The article considers all such cases of filling of the Eastern Aral Sea. The water discharge start and end dates are defined for each case. The maximum areas of the Eastern Aral Sea formed as a result of such a discharge were calculated. For each case of water discharge, the total water consumption of the Syr Darya River in the Aklak hydroelectric complex, which is located 15 km upstream from the confluence of the Syr Darya River into the North Aral, near the village of Karateren, was calculated. The movement of waters occurred due to discharge from the Northern Aral Sea in 2014-2015, when the area in the Eastern Aral Sea increased from 0 to the maximum value of 2,433 km2, is considered in most detail. It is demonstrated how the former Tshche-Bas Bay is filled with these waters from the south after reaching a certain level, sufficient to overcome the sill separating the Tshche-Bas Bay from the Intermediate Aral Sea. The formation of a separate reservoir was discovered in a small depression about 3 m deep at the northwestern end of the Eastern Aral Sea, at the entrance to the former Uzun Strait, which was not on a bathymetric map built during the pre-desiccation period. It is shown that despite the commissioning of the Kokaral Dam, during the considered period of time, the Eastern and Intermediate Aral continued to receive sufficient water as a result of discharges. The water content of the Syr Darya River in the area of the Aklak hydro complex is of decisive importance. It was established that after 2018 the period of relative low water content of the Syr Darya River began, as a result of which the annual runoff of the Syr Darya River at the Aklak hydro complex decreased from 3,033 million m3/year in 2018 to 551 million m3/year in 2022, i.e. by a factor of 5.5. This water amount was not enough even to maintain a level of 42 m in the North Aral, as a result of which the Sari-Cheganak Bay, located in the northeast of the North Aral Sea, quickly became shallow. Of course, the discharge of water through the Kokaral Dam also ceased, leaving no water in either the Intermediate or Eastern Aral.
Keywords: Aral Sea, East Aral, North Aral, water discharge through Kokaral dam, water consumption in the Syr Darya River, Aklak hydro complex, Aqua/Terra satellites
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