三江并流区德钦县积雪面积时空变化分析

Temporal and spatial variation of snow cover in Deqin County of three parallel rivers region

德钦县积雪储量是滇西北重要的淡水资源,对三江并流区的河流补给、缓解水资源压力起着重要的调节作用。基于10景TM、ETM+、OLI影像、DEM和气象数据,采用NDSI指数提取了德钦县1989,1996,2000,2009,2015年5个时期的积雪信息,分析了积雪面积时空变化特征,探究了积雪与气候变化的关系。结果表明:时间上,积雪面积呈现逐年衰退的变化趋势;26 a来,积雪面积由819.884 7 km^2减少到619.115 4 km^2,减少了24.5%,年平均减少7.44 km^2;空间上,不同海拔带内积雪面积都在减少,在海拔1 464～3 000 m积雪面积衰退最为激烈和明显,海拔3 001～4 000 m积雪面积变化也较为迅速,积雪主要分布在海拔4 001～6 740m,且缩减速度较为缓慢;26 a来区域温度升高和降水减少加速了积雪面积减少。

The snow reserves in Deqin County is an important freshwater resources and dominates in runoff recharge and water resources pressure allevation in the three parallel rivers region. This paper uses NDSI index to extract the snow cover information of Deqin County in 1989,1996,2000,2009 and 2015 based on 10 scenes of TM,ETM ＋,OLI images,DEM and meteorological data and analyses the spatial and temporal variation characteristics of snow cover area and the relationship between the changes of snow cover and climate. The results show that the snow area showed a decline trend year by year,decreased from 819. 8847 km^2 to 619. 1154 km^2 in 26 years,accounting for 24. 5% of the total,with yearly reduction of 7. 44 km^2; the snow areas in different altitude zones all reduced and the most quick and obvious in the zones of 1464 ～ 3000 m,comparably quick in the zone of 3001～4000 m; the snow cover distributed in the altitude of 4001～ 6740 m reduced most slowly. The increasing temperature and decreasing precipitation accelerated the shrinkage of snow cover area in recent 26 years.