VARIATION TREND OF CLIMATE CHANGE AND ITS EFFECT ON ANNUAL RUNOFF IN THE LAKE BALKHASH BASIN, CENTRAL ASIA

Using the data from 13 meteorological stations in the Lake Balkhash Basin (LBB), we found that temperature and precipitation in the LBB had a significant increasing trend over the past 100 years, at rates of 0.20 degrees C/ decade and 17.08mm/decade respectively. Warming trend in winter and wetting trend in summer are most remarkable, at rates of 0.44 degrees C/ decade and 6.44mm/decade respectively. The warming-wetting change is most remarkable in the southern mountain region of the LBB. The change of precipitation had a great impact on runoff The temperature variation can influence evaporation and glacial melting, which in turn leads to runoff change. Using the method of slope change ratio of cumulative quantity(SCRCQ), we calculated the contributions from precipitation, evaporation, and human activities to the entire runoff change in all river sections, and the contributions were 51.22 %, -9.07 %, and 57.85 %, respectively. The water level in the Balkhash Lake has been affected by climatic and hydrologic variables (including air temperature, precipitation, and runoff), human activity, and combinations of the two.