1961-2015年河西走廊强降水的时空演变及其对植被的影响

基于1961-2015年河西走廊的降水及卫星遥感资料的分析,发现河西走廊强降水出现次数增加,1991年以来强降水出现站数明显增多、最大日降水量增多较大,河西走廊强降水的变化呈现出区域集中、强度增大的变化趋势.历年连阴雨出现站数趋势平稳,在2007年以来站数和次数均出现减少趋势,最长持续时间呈缩短趋势,但连阴雨最大雨量呈增大趋势,尤其是2000年以来,区域性连阴雨出现次数增多,最大雨量增大,连阴雨事件强度增强.年降水量和连阴雨雨量与植被中覆盖度面积主要呈正相关,与低覆盖盖度多呈负相关,河西西部连阴雨有效数据较少,东部相关性可能受到灌溉率等的影响.

Spatiotemporal Variation of Heavy Rainfall and Its Effects on Vegetation in the Hexi Corridor during the Period of 1961-2015

Based on the daily precipitation data from 19 meteorological stations in the Hexi Corridor during the period from 1961 to 2015,the thresholds of daily precipitation were determined station by station.The spatiotemporal variation and distribution of heavy and extreme precipitation events in the Hexi Corridor in recent 50 years were studied.The results revealed that the heavy rainfall events,stations where heavy rainfall occurred and maximum daily precipitation were all in an increase trend in the Hexi Corridor during the period from 1991 to 2015.The number of stations where continuous rainfall occurred stabilized.The duration of the longest rainfall process shortened.However,the maximum precipitation of continuous rainfall was in an increase trend during the period from 2007 to 2015.There was a positive correlation between the moderate vegetation coverage and the annual precipitation and continuous rainfall,but a negative one between the low vegetation coverage and the annual precipitation and continuous rainfall.The available data of continuous rainfall data were insufficient in the west Hexi Corridor during the period from 2000 to 2015,and the correlation in the east was maybe affected by irrigation.