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Flood Frequency Analysis of Ikpoba River Catchment at Benin City, Edo State Nigeria
Abstract
A flood frequency analysis (FFA) of Ikpoba River Catchment at Benin City, Edo State Nigeria was undertaken using the Extreme Value Type -1 (Gumbel) distribution applied to annual flood series obtained from the discharge measurements carried out by the Benin Owena River Basin Development Authority (BORBDA) for the period between 1989 to 2000 (12 years).
The Gumbel distribution was applied for return periods of T = 1.05 to 1000 years. Our results indicate that for return periods of 2yrs, 5years, 10years, 25years, 50years, 100years, 200years and 1000 years commonly used for engineering design of hydraulic structures, the estimated discharges are 45.86m3/s, 53.36m3/s, 66.64m3/s, 77.09m3/s, 84.84m3/s, 92.55m3/s and 100.22 m3/s and 118m3/s respectively which values can be used for hydraulic design of structures in the catchment area.
The Gumbel distribution was applied for return periods of T = 1.05 to 1000 years. Our results indicate that for return periods of 2yrs, 5years, 10years, 25years, 50years, 100years, 200years and 1000 years commonly used for engineering design of hydraulic structures, the estimated discharges are 45.86m3/s, 53.36m3/s, 66.64m3/s, 77.09m3/s, 84.84m3/s, 92.55m3/s and 100.22 m3/s and 118m3/s respectively which values can be used for hydraulic design of structures in the catchment area.
