Flood Risk Assessment and Climate-Resilient Drainage Design for Communities in Essien Udim Lga, Akwa Ibom State, Nigeria

Abstract

This study assessed flood risk and developed climate-resilient drainage design strategies for communities in Essien Udim Local Government Area (LGA), Akwa Ibom State, Nigeria. Increasing flood occurrences in the area have been linked to intensifying rainfall extremes, rapid land-use changes, and inadequately designed drainage systems. Field measurements of flood depth, drainage capacity, soil infiltration rates, elevation, and land cover characteristics were collected alongside socio-economic impact data. Rainfall records (2021–2025) were analyzed using the Mann–Kendall trend test and Standardized Precipitation Index (SPI) to determine hydro-climatic variability. Pearson correlation, multiple regression, and Principal Component Analysis (PCA) were employed to identify key flood determinants and assess community vulnerability, while hydraulic simulations were conducted to evaluate drainage performance. Results revealed significant upward trends in maximum 1-day rainfall (Z = 2.41, p = 0.016), 3-day rainfall (Z = 2.78, p = 0.005), and SPI (Z = 1.95, p = 0.049), confirming intensifying rainfall extremes. Impervious surface coverage, drainage efficiency, and elevation were identified as primary predictors of flood depth, jointly explaining 78% of observed variability. Vulnerability assessment indicated that communities such as Ekpenyong and Odoro Ikot exhibit high exposure and low adaptive capacity. Model validation statistics (NSE = 0.81, RMSE = 0.23 m, R² = 0.84) demonstrated strong predictive reliability. The study concludes that flood risk in Essien Udim LGA is driven by the interaction of climatic extremes, inadequate drainage infrastructure, land-use patterns, and socio-economic vulnerability. Climate-adjusted drainage design, green infrastructure integration, routine maintenance, and community-based adaptation are recommended to enhance long-term flood resilience.