Vegetation condition has a close relation with the dry and wet degree of environment.The normalized difference vegetation index(NDVI) is a good index indicating the condition.Generally

the NOAA/AVHRR data may be used to monitor drought and there are some successful methods such as anomaly vegetation index(AVI) for the purpose.At present

the Flemish Institute for Technological Research

Belgium(VITO)

freely provides a set of SPOT VGT NDVI data from 1998 to 2006.Using the AVI calculated from the SPOT VGT NDVI data from 1998 to 2006

drought grade in the monitoring year was classified.The study successfully monitored the drought that occurred in Ningxia Hui Autonomous Region

Northwest China

in 2000.The result was also validated using meteorological observation data collected from some weather stations in Ningxia.It is shown that the method can be used not only to accurately monitor drought range and degree but also to help the governmental departments in related areas.