TITLE:
Trends in Vegetation Response to Drought in Sudano-Sahelian Part of Northern Nigeria
AUTHORS:
Blessing Bolarinwa Fabeku, Emmanuel C. Okogbue
KEYWORDS:
Drought Occurrence, Vegetation Response, Standardize Precipitation Index (SPI), Normalized Precipitation Index (NDVI), Greenness Index (GI), Drought Spatial Map
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.4 No.4,
September
25,
2014
ABSTRACT: This
study was carried out to evaluate the drought occurrence and its implication on
vegetation cover over the Sudano-Sahelian zone of the Northern part of Nigeria.
Monthly mean Rainfall data for the period 40 years (1971-2010) were obtained
from Nigeria Meteorological Agency (NIMET) for each of the meteorological
stations present and functioning in this region for climatic analysis.
Standardized Precipitation Index (SPI) was used to analyze drought occurrence
on a time scale of five (5) months that cover the period of raining season over
the study area. Also Satellite data over the selected part of the study area
for three different epochs, 1986, 2000 and 2005 were used for vegetation
response analysis. The SPI values were interpolated using Inverse Distance
Weighted (IDW) interpolation technique in ArcGIS 9.3 to generate Drought
Spatial Pattern Map for each selected modeled years. The vegetation response
indicators used are land cover maps and Greenness Index (GI) maps. Land cover
categories were classified into five levels: Dense Vegetation, less dense
Vegetation, Settlement/built up, Bare Surface and Water body. The results based
on the ground truth (rainfall) data show that many years of drought episode
were experienced over the study area. On the other hand, the prime indicators
(Land cover and GI maps) used in this study also depicts the changes that took
place over the study area in response to this climatic anomaly (drought) and it
could be noted that there was dramatic reduction in the occurrence towards the
end of the last two decade, 1990-1999, which simply indicated improvement in
rainfall even in 2000 and the later years.