The small Aral is falling again: twenty years after the Kok-Aral dam, satellite level, lake area and Syr darya inflow, 1993-2026

In 2005 the Kok-Aral dam separated the northern part of the Aral Sea, the Small Aral, from the drying southern part. This study uses satellite altimetry from 1992 to 2026, Landsat measurements of the lake's area in 2016-2024 and the winter inflow of the Syr Darya recorded by the Interstate Commission for Water Coordination to ask whether the gain from the dam has lasted. The summer level of the Small Aral rose by 1.52 m in the first year after the dam, from 40.64 m in 2005 to 42.16 m in 2006, and stayed at about 42.48 m on average until 2020. After 2020 it fell to 41.64 m on average in 2021-2025, and the lake's area fell by about 7%. The fall is not an artefact of a change of satellite: at each of the four changes of satellite the old and new instruments agree within a few centimetres. It coincides with less water reaching the lake: the winter inflow at the Karateren gauge fell from 3.32 km3 on average in the winters of 2015/16-2017/18 to 1.35 km3 in 2018/19-2024/25, and the lake's area follows the sum of the last two or three winters (r = 0.81 and 0.91) more closely than the last winter alone, although with only seven or eight years these figures are uncertain. The results do not support the author's view that the dam brought little change, but show that its gain is not permanent.