Climate processes in the nival-glacial zone of Trans-Ili Alatau and their impact on mountain glaciation and runoff

Abstract

On the basis of the latest monitoring data of a high-mountainous glaciological station of Institute of Geography, Republic of Kazakhstan on modern climate changes in the nival-glacial zone and their occurrences in the mode of river runoff are analyzed. Tendencies of changes of the 10 meteorological elements for various intervals of averaging as for the years 1971–2011 are studied (winter, summer and annual mass balance of Central Tujyksu Glacier and annual runoff of the rivers of Ili river basin). Results of the analysis confirm continuation of climate warming in the region; the air temperature in nival-glacial zone raised is commensurable to growth of temperatures in foothill and low mountain zones; the dates of the beginning of snow melting and dates of stable transition of air temperature through 0 °C in the spring and on later terms in the autumn moved for the earlier time; the quantity of precipitation tended to increase especially for the cold period and July. Average temperatures of the cold period grew more intensively than in the summer period. Warming of the nival-glacial zone induced not only due to increase of summer temperatures, but also due to appreciable increase of autumn air temperatures especially in September as well as due to increases of the warm period duration. Starting from 1975 the significant positive trend in long-term fluctuations of runoff for all researched rivers is observed. For the period 1975–2011, steady growth of seasonal snow cover depth in the nival-glacial and middle-mountainous zones of Zailiyskiy Alatau is observed. Positive changes in the fluctuations of winter, summer and annual mass balance of glacier are observed. Nowadays natural climatic influences to the rivers runoff in Ili-Balkash region and renewed surface water resources exceed anthropogenic influences which were determining in the zone of runoff dispersion during the low-flow period.