ASSESSMENT OF DROUGHT SEVERITY IN NORTHERN NIGERIA USING MULTI-INDEX DROUGHT INDICATORS (1980–2023)

Abstract

Drought is one of the most persistent climate-related hazards affecting Northern Nigeria, with significant implications for agricultural productivity, water resources, ecosystem stability, and food security. Despite increasing drought occurrence, most previous studies have relied on single drought indices, limiting comprehensive understanding of drought dynamics under changing climatic conditions. Therefore, this study assessed the temporal, seasonal, and spatial characteristics of drought in Northern Nigeria from 1980 to 2023 using a multi-index approach. Monthly hydro-climatic variables, including precipitation, maximum and minimum temperature, potential evapotranspiration, actual evapotranspiration, soil moisture, and runoff, were obtained from the TerraClimate dataset (approximately 4-km spatial resolution), while observed rainfall and temperature records from the Nigerian Meteorological Agency were used for validation. Drought conditions were evaluated using the Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and Evaporative Demand Drought Index (EDDI). Data were analysed using descriptive statistics, frequency analysis, temporal trend analysis, seasonal analysis, spatial mapping, comparative analysis, and Pearson correlation implemented in Python and ArcGIS 10.4. The findings revealed pronounced temporal and spatial variability in drought severity, with severe drought conditions occurring during the early 1980s and intensifying again after 2020. Near-normal conditions were the dominant drought class, although recurrent moderate-to-extreme drought events were observed throughout the study period. Spatial analysis identified persistent drought hotspots across the northwestern and southern parts of Northern Nigeria, while EDDI showed that increasing atmospheric evaporative demand significantly intensified drought conditions. The study concludes that integrating multiple drought indices provides a more reliable assessment of drought dynamics than a single indicator. It is recommended that multi-index drought monitoring be incorporated into national drought early warning systems to strengthen climate adaptation, agricultural planning, and sustainable water resource management in Northern Nigeria.