Abstract: The spatio-temporal evolution of vegetation in the water source area of the middle route project of South-to-North Water Diversion is researched via data processing and analysis using ArcMap software and Unary Linear Regression Model based on the Moderate-resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data in 2010—2019.The causes of vegetation change are also discussed in association with the data of surface temperature,precipitation and soil humidity in the water source area.Results manifest that (1) the distribution of NDVI in the source area is strongly correlated with terrain.From 2010 to 2019,the mean value of NDVI displayed a steady upward trend.(2) From 2013 to 2015,NDVI showed a notable decrease-recovery trend,which is possibly related to the extreme drought due to land surface temperature and precipitation anomalies in 2014,the restoration of precipitation and the increase in the water level of Danjiangkou Reservoir in 2015.(3) From 2010 to 2019,the areas with significant changes in NDVI mainly concentrated in low-altitude densely populated areas,indicating that the vegetation in these areas is more susceptible to climate change,urban expansion and the policy of “farm land returning to woodland and planting trees”.In addition,the rising of the water level of Danjiangkou Reservoir after the running of middle route project led to the reduction of NDVI in the reservoir area.The research findings offer scientific basis for the restoration and protection of natural vegetation in the water source area of the Middle Route Project of South-to-North water diversion.

Key words: spatial-temporal variation of vegetation, Middle Route Project of South-to-North Water Diversion, water source area, MODIS, NDVI