The Application of TVDI in Drought Monitoring for Winter Wheat in Spring
TVDI在冬小麦春季干旱监测中的应用

Droughts hazard occurs frequently in nature and has a great impact on agriculture.Timely monitoring and assessment of drought conditions is critical to mitigate its effects.Using NOAA/AVHRR satellite data,we derived the normalized difference vegetation index (NDVI),soil-adjusted vegetation index (SAVI),land surface temperature (LST) and analyzed the spatial characteristics of vegetation indices and land surface temperature.The temperature vegetation dryness index (TVDI) was used to monitor the winter wheat drought conditions from March to May of 2005 in the middle-south part of Hebei Province.The results showed that the correlation of soil moisture with TVDI based on SAVI was better than that based on NDVI.The analysis of TVDI and soil moisture data from weather stations' measurement demonstrated that a good correlation existed between TVDI and relative humidity of soil at 10cm and 20cm.Therefore,TVDI is a better indicator for operational drought monitoring.