ASSESSMENT OF DROUGHT IN SOME STATES OF NORTH-EASTERN NIGERIA

Abstract

Drought is one of the most expensive hazards and widespread natural menace, as it occurs in all geographic region of the earth. In Northern Nigeria, studies on drought appraisal have been carried out using rainfall based index which do not take account of other variables and triggers like temperature. Hence, a temperature based index, Standardized Evapotranspiration Index (SPEI) at 3 and 6 months accumulation period was adopted. The study employed the modified Blaney-Morin equation, that is, the Blaney-Morin Nigeria, as its evapotranspiration model for calculating evapotranspiration (PET). The north-eastern part of Nigeria was taken as a case study using hydrometeorolgical data. The analysis of the decadal trend of the rainfall in the study area shows that the last 5 years (2016-2020) witnessed increased rainfall in all the stations with Bauchi having the highest amount of rainfall of 1567.74mm while the analysis of temperature trend shows that monthly temperature was highest in Yola with the peak value of 29.86oC in 2016. The degree of temperature follows an increasing trend in all the stations in the last five years of the study period. The Standardized Anomaly Index further buttressed the likelihood of increased temperature due to global warming as more warming years were observed in the last five years of the study period. The analysis of the drought severity shows that the 3-month time scale demonstrates higher incidences of moderate to severe drought while the 6-month time scale demonstrated a lesser incidence, although, near normal incidences were more pronounced in both timescales. The last five years were shown to be prone to the drought incidences which is likely due to the effect of increased temperature as observed in both accumulation periods; however, the critical years were 2019 and 2020 with moderate to severe drought in the months of August to September for SPEI-3; and October to November for SPEI-6 while the year 2008 was the wettest year across all stations. It was recommended in view of the findings that both accumulation periods can be used for drought monitoring due to the transition from meteorological to hydrological drought, hence, the need for adequate drought monitoring framework for drought preparedness should be put in place.