Glacial Runoff in China: An Evaluation and Prediction for the Future 50 Years

Abstract

Functional models of glacier system variation are established,on the basis of the structure of glacier system and the nature of the equilibrium line altitudes at the steady state(ELA_0),using Kotlyakov-Krenkes's equation relating annual ablation of glacier and mean summer temperature.The models are applied to study the response of glacial runoff to climatic change.The effect of decreasing air temperature due to rising of ELA_0 and reduction of glacial area were taken into account.Based on the data of glacier inventories of China and the models,glacial runoff in China was calculated and possible variation trend of glacial runoff in the future 50 years was evaluated under different temperature rising rates.It is shown that: 1) The total glacial runoff of China was 615.7×108 m~3 in 1980,and was 659.66×108 m~3～682.24×108 m~3 in 2000,7.13%～10.8% more than that in the 1980s,yet the glacial area and volume decreased by 1.07%～1.62% and 1.14%～1.73%,respectively,from 1980 to 2000;2) The glacial runoff will continuously increase on the average from 2000 to 2030,and reach the maximum,about 675.15×108 m~3~707.91×108 m~3,in about 2030,with a rate of 9.6~ 15.0%;3) After 2030,the glacial runoff will decrease,but until 2050 the total glacial runoff will be 8.6~13.6% more than that in the 1980s on the average.So it is a favorable opportunity to utilize the glacial runoff in the years from 2000 to 2050,but it is also the period with high-frequent hazards from glaciers;4) Under the extremely climate warming scenario,0.05 K·a~-1,the glacial runoff increasing rate will amount to 26.5% at the runoff climax and the glacial runoff level will be lower than that of the 1980s and 57% of glacial volume will be lost by the end of this century.