博斯腾湖流域山区地表径流对近期气候变化的响应

Response of Land Surface Flow to Climate Change in the Mountain Regions of Bosten Lake Valley,Xingjiang,China

近年来,在全球和区域气候变化影响下,新疆博斯腾湖主要产流区开都河出山径流呈现异常波动,引起气候变化研究的关注。鉴于产流区复杂地形和径流补给特征以及传统观测资料的不足,借助雷达、微波及可见光等多源遥感数据从山区降水、积雪和冰川等方面与出山径流变化关系进行比较来揭示径流突变原因。结果表明,产流区平均径流深与降水量关系的转变是引起出山径流异常波动直接原因;进一步的冰川变化分析显示,径流深的波动主要由冰川融水径流变化引起:20世纪80年代中期后的温度上升加速了山顶冰川消融,导致1987～2002年的径流增加和湖泊水位升高;1984～2000年间,流域山顶冰川面积消退近40%,随着分布在较低海拔,对温度升高最敏感的中小冰川的消失,冰雪消融带来的径流增加效应开始减弱;2002年后,在流域气温、降水等变化并不显著的情况下,出山径流量却急剧降低,反映了特定冰川分布条件地区在气候变暖中融水径流先升后降的现象。

The runoff shows an unusual fluctuation in mountain areas of the Bosten Lake valley affected by the regional and global warming in the past decades. This paper makes analysis on the precipitation, snow cover and glaciers changes by multi-sources remote sensing data. Results reveal that proportion shift between runoff depth and precipitation contributes mainly to this fluctuation, and the change in glacier-meh upstream plays a crucial role in this process. Glacier-meh makes valley water resources concentrate to the lower reach （terminal lake）, which has resulted in the ample runoff period （ 1987 - 2002）. Small and middle-sized glaciers are more sensitive to temperature rising, with the gradual diminishing of these scale glaciers situated in a relative low-altitude position the watersupply from melting glaciers lessened. This change has induced the phenomenon of sharp drop in runoff after 2002. As a result, runoff depth fell back to a normal level under the mean precipitation, which also reflects the fact of rising-falling curve in glacier-meh runoff during climate warming.