Impact of Drainage Density and Geological Factors on Flood Risk: A Comprehensive Study of Abia State

Abia State in Southeastern Nigeria is characterized by diverse topography, variable rainfall, and significant urbanization, all contributing to its flood risk profile. This study aims to assess flood risk across Abia State by analyzing drainage density, slope, land use/land cover (LULC), rainfall distribution, and proximity to water bodies to categorize flood risk levels and provide insights for targeted flood mitigation. A comprehensive spatial analysis was conducted using data on drainage density, slope, LULC, rainfall, and proximity to rivers. Drainage density was classified into five categories, and areas were mapped to highlight varying flood risk levels. Slope data helped determine terrain's influence on runoff, while LULC data assessed the impact of urbanization and vegetation on flood susceptibility. Rainfall patterns were analyzed to identify regions prone to flooding, and the relationship between proximity to water bodies and flood risk was also evaluated. Results revealed that 50.07% of Abia State is at moderate flood risk, 53.46% at high flood risk, and 34.41% at very high flood risk. High-risk areas are characterized by dense drainage networks, steep slopes, significant rainfall, and close proximity to water bodies. Aba North, Aba South, and Oboma Ngwa are among the most vulnerable regions, while areas with low drainage density and gentle slopes are the least prone to flooding. The study underscores the importance of improved drainage infrastructure, urban planning, and flood management, particularly in high-risk zones. The findings provide critical insights for enhancing resilience and mitigating the impacts of flooding in Abia State, offering a novel approach to regional flood risk assessment.