A STUDY OF RAINFALL AND VEGETATION DYNAMICS IN THE AFRICAN SAHEL USING NORMALIZED DIFFERENCE VEGETATION INDEX

A recently developed method for large-scale monitoring of vegetation growth is the normalized difference vegetation index (NDVI) derived from reflectance data from the NOAA satellites. This study is an investigation of the relationship between the NDVI and the rainfall in the semi-arid Sahel of West Africa. The temporal and spatial patterns of both variables are evaluated for six vegetation formations in the region. There is a strong linear relationship between NDVI and rainfall if annual rainfall lies between about 150 and 1000 mm. The best correlation is between NDVI and rainfall in the concurrent plus two previous months. The study also suggests that the phenology of NDVI appears to reflect soil moisture availability and that water-use-efficiency varies markedly among the six vegetation formations.

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