LONG-TERM FLUCTUATIONS OF GLACIER PROCESSES AND RIVER RUNOFF IN CENTRAL ASIA UNDER CURRENT CLIMATIC CONDITIONS

V. G. Konovalov and M. V. Williams

Space and time variation of statistical parameters of the long-term series of river runoff averaged over the year and the growing season (April—September) in the Amu Darya and Syr Darya basins is studied using measurements at 30 hydrological stations for the periods 1932—1961 and 1962—1991. Analysis has shown that there was a decrease in annual and seasonal discharges in the Amu Darya and Syr Darya basins in 1962—1991. Compared with a relatively weak change in the long-term mean, its variability has increased by 22—24% on average. The mean, maximum, and minimum changes in the variation coefficients of annual and seasonal runoff proved to be nearly the same. The 30-year impact of decreased glacier processes in the Pamir and Gissaro-Alai is evaluated by the example of large catchments in Central Asia. A regional empirical relation is determined between the mean rate of glaciation decrease and the mean statistical probability of the climatic index of the accumulation and ablation balance.