Temporal Patterns of Flooding in the Midstream and Downstream Catchments of the River Kaduna Basin, Kaduna, Nigeria

Abstract

This study examines the temporal patterns of flooding in the midstream and downstream catchments of the River Kaduna Basin, with a view to improving flood risk assessment and management. A mixed-methods approach combined GIS-based multi-criteria analysis (MCA) with a household survey of 384 respondents within a 1 km river buffer. Physical factors (rainfall, slope, soil permeability, wetness, NDBI, NDVI, drainage) were weighted using the Analytic Hierarchy Process to generate flood occurrence frequencies and predictions via Monte Carlo simulation. Flooding was strongly clustered (Moran’s I = 0.67, p<0.001). Chikun, Tudun Wada North, and Nassarawa wards constitute a persistent high-risk belt covering 32% of the study area. Time-series decomposition of flood vulnerability over an 18-year period revealed an upward trend, from 0.424115 in 2016 to 0.428838 in 2034. Vulnerability distribution is: Very High 11%, High 20%, Moderate 24%, Low 16%, Very Low 29%. Areas experiencing annual flooding grew from 28% (2016) to 37% (2024), and average flood duration increased from 3.2 to 4.8 days. The most pronounced increase occurred in the Very High vulnerability category, which expanded by 54.9 km2 (10.9%) over the study period. The study recommends risk-sensitive land-use planning, ecosystem-based measures, institutional coordination, and community resilience building.