Salisu A.*, Abubakar K., & Ahmad I.A. (AUTHORS)
Department of Geography, Federal University Dutsin-Ma, Nigeria
*Corresponding Author’s Email: sabdulmalik@fudutsinma.edu.ng
ABSTRACT: Drought represents one of the most economically damaging natural hazards in semi-arid agricultural systems, and its relationship with the length of the growing season (LGS) is central to understanding food security vulnerability in northern Nigeria. This study investigated drought intensity and its relationship to total rainfall distribution within the growing season for Katsina Local Government Area (LGA) over the period 1985–2024. Four years of daily rainfall data from the Nigerian Meteorological Agency (NIMET) were used to compute annual LGS values using the Ilesanmi (1977) method. Drought intensity was characterized using the Normalized Rainfall Index (NRI) as defined by Turkes (1996), which standardizes annual or seasonal rainfall totals relative to the long-term mean and standard deviation. A modified seven-class NRI classification was applied, ranging from ‘Very Wet’ (NRI ≥ 1.31) through ‘Near Normal’ (−0.50 to 0.50) to ‘Severe Drought’ (NRI ≤ −1.31). Correlation analysis was used to quantify the relationship between NRI and LGS. Results revealed that drought conditions (NRI < −0.50) were recorded in 19 out of 39 years (47%), including four severe drought years (1985, 1991, 1993, 1996). Severe droughts were associated with LGS values of 70–85 days — critically short for most staple cereal varieties. In contrast, wet years (NRI > 0.50) had LGS values of 110–160 days. A strong positive correlation was found between NRI and LGS (r = 0.72), confirming that drought intensity is a primary determinant of effective growing season length. These findings highlight the urgency of drought-responsive agricultural planning and the integration of drought monitoring indices into early warning systems for food security management in the Sudan Savanna zone.
Keywords: NRI; Seasons; Correlation; Katsina; Food security; Sudan Savanna