Spatial-temporal characteristic of drought in northern Nigeria
This paper examines the spatial and temporal characteristics of droughts during the rainy season (May-October) for 1965-2010 over northern Nigeria using monthly rainfall data from station rain gauges. The spatial distribution of rainfall is identified by Standardized Precipitation Index (SPI), which also characterizes specific temporal drought events. Mann-Kendall trend test is applied to analyze the changes in the drought trend and also to confirm the significance of the observed trends. The results of the analysis show major changes in the drought characteristics in northern Nigeria during the major dry episodes (1973-1983) and major wet episodes (1996-2010). For the period 1965-1985, all the stations showed a decreasing trend both in 3 and 6 months time scales. In contrast, 87.5% of the stations showed an increasing trend for the period 1985-2010, with Maiduguri, Nguru, Kano, Katsina and Yelwa showing significant increases, the prolonged dry spell in the 1970’s and 1980’s was shown clearly in some of the analyses. A large number of further observations would be required to put some of these findings on a finer basis for the Sahelian drought characterization. It is recommended that agricultural organizations and disaster management parastatals should be pro-active in drought adaptation and mitigation planning.
Keywords: Standardized Precipitation Index, Spatial, Temporal, drought, Mann-Kendall, trend.