河西内陆河流域绿洲面积对地表径流的响应

Response of oasis area to the surface runoff in Hexi inland river basin of China

利用NASA AVHRR NDVI 3g遥感资料计算得出河西内陆河流域植被归一化指数(Normalized Difference Vegetation Index,NDVI),将NDVI>0.20区域视为绿洲,通过计算绿洲区NDVI的变差系数和线性斜率分析1982-2013年绿洲面积变化,并进一步分析其对地表径流的响应特征。结果表明:河西内陆河流域绿洲整体呈扩张趋势,扩张区域主要在绿洲边缘区、河流两侧和尾闾;小规模斑块绿洲的破碎度呈增加趋势,连片的绿洲核心区相对稳定;绿洲面积随着出山径流变化呈现出阶段性特征,山区降水量对绿洲变化的贡献率约为地表径流贡献率的一半,冰川融水对绿洲面积变化的贡献率自东向西依次增加,绿洲区降水的贡献率则依次减少。

This paper calculated NDVI in Hexi inland river basin by using NASA AVHRR NDVI3g data,and took the region where NDVI value is larger than 0.20 in growing period as oasis,and calculated variation coefficient and linear slope of oasis NDVI to analyze characteristics of oasis dynamic change in 1982-2013 and its response to surface runoff. The results showed that oasis in the study area expanded in recent 30 years,and expansion regions were mainly concentrated in oasis fringe area,both sides and terminal of river;the fragmentation of small patch oasis increased and contiguous oasis core area was relatively stable;the contribution rate of precipitation in mountain area to oasis changes was nearly half of the surface runoff,the contribution rate of glacier melt water to oases changes increased from east to west,and the contribution rate of precipitation in oasis region decreased from east to west. The results will provide scientific understanding for analyzing the impact of glacier melt water resources on social economy in Hexi inland river basin.