TITLE:
Trend Analysis of Drought in the Guinea and Sudano-Sahelian Climatic Zones of Northern Nigeria (1907-2006)
AUTHORS:
Temidayo O. Omonijo, Emmanuel C. Okogbue
KEYWORDS:
Drought, Northern Nigeria, Standardized Precipitation Index (SPI)
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.4 No.4,
August
21,
2014
ABSTRACT: A quantitative assessment of
drought characteristics and their associated variability in the Northern
Nigeria was carried out. Monthly rainfall data for all the selected locations
which span a period of 100 years (1907-2006) collected from the Climate
Research Unit (CRU) database were used. The resolution of the data is 0.5 × 0.5 degrees in longitude and latitude. The long-term rainfall records
were analyzed for drought using standardized precipitation index (SPI). The 100
years of Study was subdivided into 10 decades. Using Ilwis GIS software, the
SPI results were presented on a spatial digitized map of northern Nigeria. This
was done using the coordinates got from the Nigerian Meteorological Agency,
Lagos Nigeria. The results of SPI analysis revealed that there were several
drought years in the study period. Analysis further revealed that decade 7 to
decade 9 (i.e. 1967-1976, 1977-1986, 1987-1996) witnessed persistent
drought in the northern Nigeria. These were classified into mild, moderate,
severe and extreme drought conditions. Near normal dry or mild drought was
predominant in the 100 years of study. Mild drought has the highest number of
occurrence in the northern Nigeria. A closer examination shows that north
eastern part of Nigeria is susceptible to moderate drought. SPI analysis for 1,
3, 6 and 12 months was carried out. According to the Nigerian Meteorological
Agency Classification, 1 month represents meteorological drought, 3 months
represents agricultural drought, 6 months represents hydrological drought and
12 months represents socio-economic drought. The SPI analysis revealed distinct
period of negative and positive values in which negative values indicate
occurrence of drought and positive values imply there is no drought. This study
has provided useful information and pro-active intervention to reduce the
impact of drought which will be helpful to effectively plan rain-fed agriculture
in northern Nigeria.