Assessment of severity of drought in some northern Nigeria states using Drought Severity Index (DSI₅)

Abstract

Drought in various part of the northern Nigeria has been a regular occurrence over the years and has become a subject of concern to many researchers. This research considered a five-month initiation and termination sequence in the monthly precipitation data analysis of fifteen selected stations between 1960 and 2012 with the aim of identifying (i) years of drought (ii) the occurrence of major drought events and (iii) the dominant drought intensity in the region. The data were first subjected to a non-parametric test for homogeneity and thereafter, a drought severity index based on five-month (DSI₅) cumulative precipitation anomalies was used to identify the years of drought and to estimate the drought severity of the years. The results revealed that mild drought was dominant within the region having an average percentage occurrence of 43.61% with18.63% wetness. The 1960s was the wettest decade while the extreme drought events were observed in 1970s but with much prevalence in 1973 and 1977 and particularly persistent in the 1980s when considered on the decadal scale. Years of mild droughts were more frequent at Maiduguri, Bauchi, Sokoto, Kano and Zaria stations. Drastic approaches on how to possibly reduce the hazardous effects of drought occurrences in the region include adequate agricultural extension services to educate farmers on the implications of the dominant drought intensity and the ways to ameliorate its effects.

Keywords: Drought severity index; Precipitation anomalies; Surface-water; Northern Nigeria