Agricultural drought monitoring in Shanxi by using temperature vegetation dryness index

Considering the conditions of droughts occurred frequently in recent years, especially the agricultural drought, Shaanxi Province was selected as the study area the NDVI (Normalized difference vegetation index) and LST (land surface temperature) , and to establish for the first time LST-NDVI feature space using the compound MODIS data from in 2014, June through August. Then, the spatial distribution of drought in the Spring Maize at Different Growth Stages were obtained based TVDI (temperature vegetation) ,and the variation tendency of the drought in Shaanxi was analyzed. TVDI was verified using the 0-20cm relative soil moisture. The results showed that the drought more serious, and the disaster area is growing, from the spring maize seven-leaf stage to tasseling period. A trend is demonstrated expanding from east to west. The TDVI was validated by using 0-20 cm relative soil moisture data, and it was found that the TDVI and soil moisture had better correlation, at the significance level of 0.01. The TDVI could better reflect the drought status of spring maize at different growth stages.