Frequency and Distribution of Intense Rainfall in Uyo - South Eastern Nigeria

Abstract

Estimates were made of the magnitude, frequency and distribution of extreme
rainfall events in a humid tropical environment. Some of the parameters include the infrequent occurrence of maximum rainstorms, % of total annual rainfall >25mm, >50mm and >100mm as well as the probable maximum precipitation based on the Chow\'s general frequency formula. The probable maximum precipitation was calculated for Uyo using the formula P.M.P. =Y +sd. K
Where P.M.P. – probable maximum precipitation Y = mean maximum daily rainfall
Sd.=standard deviation of maximum daily rainfall and K is frequency factor
assumed to be 15 The computed value was 586.4mm. This value is slightly higher than those of Port Harcourt[463.5mm] Calabar[480.3mm] Benin City [453.9mm] and
Enugu[322.3mm], but certainly not as high as that of Warri. The return period for the computed value for Uyo is 30 years. Since floods [particularly seasonal are primarily due to intense and prolonged rainstorms, the data for extreme rainfall in an area are needed for design purposes such as bridges, culverts, storm drains and design of flood control structures, particularly in large cities.

LWATI: A Journal of Contemporary Research Vol. 5 2008: pp. 379-387