Application Study of Temperature Vegetation Drought Index in Guangxi Xijiang River Basin Autumn Drought Monitoring

To explore the Guangxi Xijiang River Basin changes rule and influence factors of autumn drought, enhanced vegetation index (EVI) and land surface temperature (LST) data were used to establish the EVI-LST feature spaces, using a linear regression method to simulate the temperature vegetation dryness index trend. The result showed that: the autumn drought in the study area increase gradually from September to November. The main area of heavy drought in the northeast, the drought distribution of the north to the south of diminishing trend. Temperature vegetation dryness index change trend of average was 0.33%; high value area distribution in of northwest and southeast, central is low. The proportion of karst area drought for 76.66%, the proportion of semi-karst area drought for 71.9%, and the proportion of non-karst area drought for 68.1 %, Karst area drought ratio is greater than the non-karst area. Drought distribution of Guangxi Xijiang River Basin significantly affected by altitude. With the rise of altitude, drought area ratio showed an increasing trend. Temperature vegetation dryness index can be greatly used in drought early warning and monitoring of Guangxi Xijiang River Basin, this method can be used in long-term and large-scale drought monitor and forecast in real-time.