Vegetation response to rainfall as monitored by NOAA-AVHRR

Rainfall is an important meteorological parameter, which influences the type of vegetation in a region. The relationship between rainfall and vegetation is well established but it varies from region to region. Normalized Difference Vegetation Index (NDVI) is a simple index to monitor vegetation which can be derived from satellite data. Use of NDVI is well established in assessing the vigour and productivity of the vegetation. In this study an attempt has been made to find the relation between rainfall and NDVI in a few districts of Andhra Pradesh, India. The mean of maximum NDVI from 1989 to 1998 is correlated with seasonal normal rainfall. The NDVI lag to the monthly rainfall and reason for the lag based on land use of the districts was investigated. Districts were classified based on their NDVI profile and coefficient of variation of NDVI and finally the first three-month cumulative southwest monsoon rainfall effect on the seasonal cumulative NDVI of the district was correlated. The result shows that there is a high degree of correlation (r = 0.81) between the mean of maximum NDVI with the normal rainfall. The NDVI lags rainfall by two months in most of the districts and the initial three months rainfall correlates well with the seasonal cumulative NDVI.