Determination of Rainfall Return Period for Uyo, Nigeria and Design Implications Against Flood Menace

Abstract

Flood menace has become a recurring decimal in Uyo, Capital City of Akwa Ibom State of Nigeria. Rainfall return Period for Uyo Metropolis has been determined in this research using sixty years rainfall data derived from University of Uyo and Nigerian Meteorological Centre (NIMET). The results indicate that the return period will be 31 years to obtain a maximum 1-month rainfall of 929.5 mm. Moreover, it will take a return period of 15.5 years to obtain a maximum 1-month rainfall of 911mm. A return period of 2 years will be required to obtain a maximum 1-month rainfall of 471.78mm while a maximum 1-month rainfall of 284.4mm could occur monthly. In the same vain, the return period will be 31 years to obtain a maximum 1-year rainfall of 4202.8mm. Also, the return period will be 15.5 years to obtain a maximum 1-year rainfall of 3877.6mm while the return period will be 2 years to obtain a maximum 1-year rainfall of 2610.1mm. Furthermore, a maximum 1-year rainfall of 1599.4mm could occur yearly. In design against flood menace in the area, designers are strongly advised to consider these values of return period. It is recommended that government at different cities should develop design standards for flood control works and strictly monitor compliance during construction operations. Ministries of Works and Environment should be adequately equipped with modern equipment’s, properly trained staff and the emergency management units should be made more responsive to Flooding hazard. Designers of flood control works in the area should increase the design standards, quantity and mixing ratio of construction materials to at least 20% above the recommended standard values. All roads in Uyo Metropolis should be provided with properly sized and interconnected drainage system leading to a drainage basin.

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