民勤荒漠绿洲植被覆盖对地下水和降水变化的响应

Vegetation Cover Response to Groundwater and Precipitation Changes in Minqin Desert Oasis

荒漠植被的生长受制于地下水和大气降水。民勤绿洲地下水位持续下降,现大部分区域植被已无法利用地下水,降水量逐年呈略增趋势,降水逐渐成为植被生长的主要来源。研究民勤荒漠绿洲地下水位、降水量变化对植被的影响,对绿洲保护具有重大意义。本文利用2000—2018年的地下水观测数据、年降水数据结合遥感反演的NDVI数据,探究民勤绿洲年降水和地下水对植被覆盖的影响。研究结果表明:民勤绿洲地下水主要在15~30 m之间;影响绿洲植被覆盖的地下水埋深主要在1~10 m;随着地下水位下降,对植被覆盖影响降低;NDVI和年降水变化趋势一致,均呈现增加趋势,并且降水显著影响绿洲地表植被覆盖。

The growth of desert vegetation is constrained by groundwater and atmospheric precipitation.Vegetation in most areas of Minqin desert oasis is unable to use groundwater due to continuously declining groundwater level.Precipitation is increasing slightly year by year,and it has become the main water source of vegetation growth.Thus,it is of great significance for oasis protection to study the influence of groundwater level and precipitation on vegetation in Minqin desert oasis.This paper used groundwater observation data and annual precipitation data combined with NDVI data retrieved by remote sensing from 2000 to 2018,to explore the impact of annual precipitation and groundwater on vegetation cover in Minqin desert oasis.The results showed that the groundwater level in Minqin desert oasis ranged mainly from 15 to 30 m,and the buried depth of groundwater affecting vegetation cover in oasis ranged mainly from 1 to 10 m.The impact of groundwater on vegetation cover decreased with its level dropping.NDVI was consistent with the trend of annual precipitation,both showed increasing trends.Precipitation significantly affected the vegetation cover of oasis surface.