Drought Impact Assessment on Vegetation over Sudano-Sahelian Part of Nigeria
This study evaluated the vegetation response to drought over the Sudano-Sahelian part of Nigeria. Landsat and monthly rainfall data with boundary map shapefile data. The results of SPI analysis revealed that the drought saga of the 70s and 80s was also experienced over the study area but later reversed in the 90s towards the 21st century as the result show a rapid decline in its occurrence which indicates improvement in rainfall. On the other hand, the vegetation response analysis also depicted that the year 1986 was a dry year over the study area as the spatial extent cover by the vegetation was much less compared to the bare-surface. But in the 1990s, greenness has returned to the areas that were previously bare soil, an indication of improvement in rainfall amount over the area. The study therefore concluded that there exists a kind of inverse relationship between drought intensity and vegetation growth and time lag in their response to dry or wet condition.
Keywords: Drought Occurrence, Vegetation response, Standardize Precipitation Index (SPI), Normalized Precipitation Index (NDVI), Greenness Index (GI), Drought Spatial Map