Rainfall Intensity – Duration Frequency Curves for Maxima Duration Series for Ondo Town, Ondo State, Nigeria

Rainfall intensity is defined as the ratio of the total amount of rain (rainfall depth) falling during a given period to the duration of the period It is expressed in depth units per unit time, usually as mm per hour (mm/h). The statistical characteristics of high-intensity, short-duration, convective rainfall are essentially independent of locations within a region and are similar in many parts of the world. Analysis of short-term rainfall data suggests that there is a reasonably stable relationship governing the intensity characteristics of this type of rainfall [1]. Point rainfall average intensities and return periods for specified durations were calculated for annual maxima series. Plots of these were made to give the intensity – duration frequency curves. The amount of rain expected in 12 hours on the 50 – years curve is about 17.5mm per hour. Also, at the 10 – year curve, the average intensity corresponding to 12 hours is about 12.4mm per hour. This study is used for various water resources engineering designs and planning