Spatio-Temporal Assessment and Prediction of Drought in the Northeast Arid Zone of Nigeria Using Standardized Precipitation Index (SPI) under Two Climate Scenarios

Abstract

Drought is one of the most severe climate-related hazards affecting the semi-arid and Sahelian regions of Nigeria, especially in the North-East arid zone, where rainfall unpredictability and rising temperatures endanger agriculture, water supplies, and socioeconomic livelihoods. This study examined meteorological drought in the northeast arid zone of Nigeria using the Standardised Precipitation Index (SPI) under two climate change scenarios, SSP2-4.5 and SSP5-8. 5. Precipitation outputs from selected CMIP6 Global Climate Models were combined with observed rainfall data from the Nigeria Meteorological Agency (NiMet) and gridded precipitation data from the Global Precipitation Climatology Centre (GPCC) for 1982–2014. Based on their rainfall simulations, MPI-ESM1-2-LR, IPSL-CM6A-LR, NESM3, and CMCC-CM2-SR5 were chosen as CMIP6 models. Droughts were estimated for two periods: 2015–2055 and 2056–2100. Distribution Mapping (DM) bias correction was applied and it significantly improved model dependability. The SPI-3 and SPI-6 indexes measured drought frequency, duration, and severity. A historical drought study showed severe and persistent droughts in 1983–1985, 1987–1988, 1990–1994, and 2013–2014. Both climate scenarios predicted increased drought occurrences, persistence, and severity, with the SSP5-8.5 scenario exhibiting more intense drought conditions, especially in the far future (2056–2100).