Assessing the Spatiotemporal Variation and Impact Factors of Vegetation Growth in Arid Inland River Basin Using Grace and Remote Sensing Data

The Tarim River Basin is the largest inland river basin in China, which the spatial and temporal patterns of vegetation cover have undergone certain changes due to the impacts of human activities and recent climate change. This study analyzed the spatio-temporal variation of NDVI and distinguished the range and extent of the impacts of climatic factors and human activities on vegetation change in the Tarim River Basin. We explored the changes in vegetation response to climatic factors and human activities based on the ERA-Interim, AVHRR NDVI3g and Gravity Recovery and Climate Experiment (GRACE) datasets. The results showed that: 1) The precipitation and temperature showed significantly increasing trend (P<0.01), at a rate of 0.62mm/a and 0.27℃/10a. The NDVI in the study area increased with a rate of 4.09×10⁴a^-1 from 1982 to 2016. The changing rate in plains was significantly higher than that in mountains. However, the terrestrial water storage (TWS) showed a decreasing trend with an average reduction rate 1.8mm±0.5/a. 2) The NDVI showed a positive correlation with precipitation and temperature and a negative correlation with TWS at regional scale. 3) The vegetation change was mainly affected by climate change in mountain area and the temperature is the main determining factor, while the plain areas were the results of the combination of precipitation and temperature, and mainly affected by precipitation. The increasing irrigation area and the comprehensive treatment project for vegetation restoration led to the NDVI increase in the mainstream. Human activities are the main driving force for vegetation growth in this area.