冰冻圈过程对中国干旱区水文环境的影响评估

Evaluation on the Impacts of Cryospheric Processes on the Hydrological Environment in Arid Land of China

冰冻圈过程对中国干旱区的水文环境和社会经济的可持续发展有着特殊的作用和意义。本文阐述了通过系统分析、比较20世纪60年代以来中国干旱区积雪、冰川和冻土的站点观测资料及遥感数据而得出的中国干旱区冰冻圈的变化。主要结果表明:自20世纪70年代到2008年,中国干旱区80.8%的冰川有退缩。由于中国干旱区的冰川中85%以上的面积都小于1.0 km2,属小型冰川,这个退缩态势的持续可在未来十年至几十年减少冰川条数。与冰川变化相反,中国干旱区积雪面积稳定,超过8.8×105km2。积雪的初始和终止日期无明显变化。冻土方面,由于平均地温变暖,高山冻土下限深度从1992年到2008年减少了7.7 m,发生着自下而上的迅速退化。综合这些结果,文中提出了几点应对这些变化对水文环境影响的建议。

In mountainous regions at the mid-and high-latitudes,the cryosphere processes such as snow accumulation,glaciation and melting and permafrost play a deterministic role in development and change of the hydrological environment and water resources and,thus,underline the sustainability of the natural and managed ecosystems and the economy of societies. In this article,data of snowfall,glaciers size,and permafrost depth from long-term observations（ since the 1960＇s） at stations in mountains across the arid region in western China,and from satellite remote sensing in recent decades,are analyzed and examined to identify the cryosphere change and its effects on availability of water resources in the past 50 years. Major results show that 80. 8% of the glaciers have shrunk in size since the 1970＇s. Because 85% of the glaciers in the region are small with areal size of 1. 0 km^2,this trend of shrinking would result in fast diminishing of glaciers in the region within the next few decades. Opposite to the changes in glacier,the snow-cover of slightly over 8. 8 × 10^5km^2 in the region has remained unchanged. So have the annual starting and ending dates of snow accumulation. In permafrost,the rising temperatures have caused rapid reduction in the permafrost depth. It reduced by 7. 7 m from 1992 to 2008. Based on these findings,recommendations are proposed for mitigating potential adverse impacts of these changes on surface hydrology and water resources in the arid land of western China.