Drought occurrence in the sub-humid eco-climatic zone of Nigeria

This study examined drought occurrence in the sub-humid eco-climatic zone of Nigeria using monthly rainfall data from 13 synoptic stations for the period 1970–2009. Standardized Precipitation Index and descriptive statistics were employed for the study. The result obtained showed 266 drought occurrences, with 65.79, 19.93, 9.77, and 4.51% as mild, moderate, severe, and extreme droughts, respectively. The period 1980–1989 was more prone to drought of different categories while 1990–1999 was wetter than other decades. Drought occurrences ranged from 14 times at Makurdi to 24 times at Bauchi. Severe drought occurred most at Kaduna and Ibi while extreme drought was mostly devastating at Minna. However, Bida was more affected by the combination of severe and extreme droughts than other stations. The result also showed considerable interannual variability characterized by oscillations in drought duration. The duration varied from 1 to 11 years while drought intensity ranged from − 0.01 to − 3.1.