Patterns of Lake Balkhash water level changes and their climatic correlates during 1992–2010 period

The variation in Lake Balkhash water levels during the period from 1992 to 2010 and their relationship with climate dynamics were investigated in this study, using satellite altimetry data and meteorological records from climate stations located in the lake catchment basin. The altimetry‐derived water level demonstrated a general water level increase, reaching a mean value of 8.1 cm year^?1 in July 2005, with a maximum value of 342.52 m. The increased Lake Balkhash water level was accompanied by an overall upward trend in precipitation and temperature in the catchment basin during the study period. A strong increase in the winter and spring temperature was the main contributor to the general upward temperature trend, whereas a significant change of summer and autumn precipitation was the major contributor to the annual precipitation trend. Neither precipitation nor temperature increased uniformly across the entire lake drainage basin. The study results identified the most pronounced climate change occurring in the mountainous part (>2000 m above sea level) of the basin, in the upper reaches of the Ili river, which is the main water inflow to the lake. Statistical analysis indicated the Lake Balkhash water level is strongly correlated with both precipitation and temperature. The correlations were investigated for three altitudinal strata (<1000 m, 1000–2000 m, >2000 m) corresponding to the lower, middle and upper reaches of the Ili river. The best correlations were obtained for the upper reaches of the Ili river, indicating a changing snow cover and glacier equilibrium are the main factors controlling the water level trends in Lake Balkhash.