Hydrological Modeling and GIS-Based Drainage Design for Urban Flood Management in Edaiken, Benin City, Nigeria

Abstract

Urban flooding remains a persistent challenge in rapidly urbanizing regions of developing countries, largely due to inadequate drainage infrastructure and increasing surface runoff. This study presents a data-driven approach to flood mitigation through the integration of hydrological modeling, field surveys, and Geographic Information System (GIS)-based spatial analysis in Edaiken, Benin City, Nigeria. The study area was delineated into five sub-catchments (SC1–SC5) using Digital Elevation Models (DEMs) to analyze runoff patterns and flow accumulation. Hydrological parameters, including time of concentration (0.284–0.583 hours), rainfall intensity (137.034–175.972 mm/hr), and peak discharge (0.49–2.78 m³/s), were computed using the Rational Method, while hydraulic capacities were evaluated using Manning’s equation. Results indicate that sub-catchments SC3 and SC4 contribute the highest runoff volumes due to low elevation and high flow convergence. The cumulative discharge increased downstream to approximately 7.00 m³/s, necessitating drainage dimensions ranging from 0.9 × 0.9 m to 1.0 × 1.0 m. The findings reveal that flooding in the study area is primarily driven by undersized drainage systems, poor maintenance, and rapid urbanization. The proposed drainage redesign provides a technically sound framework for improving urban drainage capacity and supporting flood risk management. This study provides a scalable framework for sustainable urban drainage planning in flood-prone cities across sub-Saharan Africa