The authors of the paper extracted the normalized difference vegetation index (NDVI) and the vegetation conditional ratio (VCR) from the MODIS images,and analyzed the relationship among NDVI,VCR and the measured data of groundwater of the same location in the research region.

Based on the method of NDVI,the NDVI of Stone Forest and other areas of Shilin county were calculated and analyzed by choosing the data of Landsat in 1977,TM in 1992,ETM and satellite image in 2000.

The index NDVI which can reflect the state of the vegetation coverage well is selected to interpret and analyze the spatial change characteristics with multi-temporal landsat TM images and the support of GIS and RS.

The relationship between the normalized difference vegetation index(NDVI) and the water cycle(water rainfall,evapotranspiration) was analyzed in the 51 catchments of the Loess Plateau.

And on month,season,growing season and year time scales,correlation between climate factor images and NOAA/AVHRR NDVI data are computed.

NDVI is an indicator of vegetation growth and its spatial distribution,with has a close relationship with climate conditions.

Phenological observation data of plant communities from 1982 to 1996 at 5 sites and a method for phenological cumulative frequency modeling were used to determine the beginning dates of local phenological seasons and their corresponding threshold values of normalized difference vegetation index(NDVI) in each year.

Corrected NDVI (C-NDVI),the temporal trends in the differences between the observed NDVI and the NDVI predicted by the rainfall,was developed to evaluate the effects of human activities on vegetation change (degradation and restoration).