Spatial and Temporal Features of Meteorological Drought Utilizing Non-Stationary Standardized Precipitation Index (SnsPI) for Designated Stations in the North-Western Region of Nigeria

Abstract

Global warming, which manifests through variability or change in climate, often attracts or intensifies extreme hydrological events such as drought. The adverse effects of this event on water resources, agriculture, ecosystems, and all facets of human endeavors have been felt across the globe. In light of this, this study evaluated the spatio-temporal characteristics of meteorological drought over selected stations in the north-western zone of Nigeria with the objectives of characterizing the drought field and establishing a homogenous drought field for effective regionalization. To achieve this, a non-stationary rainfall-based meteorological index (SnsPI) was employed to assess and characterize the meteorological drought field at different timescales of 3, 6, and 12 months for each station. At SnsPI_3, the percentage of drought severity recorded for Gusau, Kaduna, Kano, Katsina, Sokoto, Yelwa and Zaria were 6.11, 5.93, 8.45, 2.16, 8.89%, 15 and 10.5%, respectively. At the 6-month timescale, the percentages of severe conditions are 11.5% (Gusau), 10.64% (Kaduna), 8.45% (Kano), 4.23% (Katsina), 12.76% (Sokoto), 15% (Yelwa), and 16.67% (Zaria), and finally, at 12_timescale, the values are 16.26% (Gusau), 10.63% (Kaduna), 3.62% (Kano), 4.22% (Katsina), 9.09% (Sokoto), 9.09% (Yelwa) and 14.69% (Zaria). The study indicated that all the stations had experienced droughts of different severities and established that the 6-month timescale is the best for time-tuning the resolution of drought in the north-western region of Nigeria. In view of the observed shortcomings of the SnsPI and its derivatives, other indexes that take into consideration the implications of global warming by incorporating potential evapotranspiration should be considered for drought studies in the north-western region of Nigeria..