Salt accumulation and its control on the plains of Central Asia

Abstract

The water-salt budget on the plains of Central Asia in natural conditions and under significant anthropogenic impact (irrigation and construction of hydraulic engineering systems) is analyzed. It is shown that up to 87.2 million tons of salts are annually transported to the plains of Central Asia from the surrounding mountains. Under natural conditions, the larger part of the salts was discharged into the Aral Sea, Balkhash and Issyk-Kul lakes, and into deep closed depressions (Tuzkan, Sarykamysh, and others). Thus, these salts were generally excluded from the geochemical turnover. Only 40% of the salts entered the deposits and groundwater of the plains. Irrigation has transformed the water-salt budget in the area. The input of salts into the groundwater and soils increased by 30% and induced the development of soil salinization in the region. Measures for salinization control are suggested. It is necessary to stop the discharge of drainage water into the rivers and the use of saline water for irrigation purposes. The existing irrigation systems should be reconstructed, and the irrigated areas should be reduced.