The scenario forecasts of water resources of the Zhayik Caspian rivers’ basin on separate water management areas

Abstract

The possibility of making scenario forecasts of water-resources of the Zhayik-Caspian rivers’ basin on separate water management areas is considered. To characterize the modern climate, the period 1980-2000 was used as the initial one. To characterize the climate of the 21st century, the projects of climate updated until 2050 were used, which obtained in Kazgidromet by S.A. Dolgikh. The basis of the forecasting method consists of the dependence of the spring flood runoff from the degree of moistness of soil, and dependence from the amount of water reserves kept in the snow before melting begins. Take
the sum of autumn precipitation from September-October as an indicator of degree of the indirect soil
moistness, and take the amount of precipitation from November-March as the indicator of the amount of
water reserves kept in the snow. The total annual runoff is determined depending on the magnitude of
the spring runoff. There is a close relationship between these characteristics of the runoff. The quality of
the predictive dependence is tested by using the S / Ϭ criterion. Satisfactory dependence was obtained
for 10 sites. Based on scenario forecasts of the climate of the Zhayik-Caspian water management’s basin
for the period up to 2050, forecasts of water resources of the individual sites were compiled for 2025,
2030, 2035, 2040, 2045, 2050. In general, according to the Zhayik-Caspian basin, an average increase
in runoff of 5-7% is expected on two scenarios for all the years. In some areas, the runoff may increase
up to 10-15%. In the basin of the river Sagiz, on the contrary, one should expect a decrease in runoff to
80%. The predicted dependence is not obtained for the site 05.03.09.00, because the expected amount
of runoff depends on the amount of water flowing to an anabranch of the Volga river.