Dimensional And Regression Models Of Rainfall Intensity-Frequency Relations

ABSTRACT

In the design of flood control structures, there is need for rainfall intensity estimation for design discharge computation. To make the rainfall intensity values easily available in south-east and south-south Nigeria, this research developed rainfall models. Dimensional and Regression analyses were used to produce models of rainfall intensities. The dimensional models are dimensionally balanced as opposed to the other models which are based on Talbot, Benard and Quotient equations. The dimensionally balanced models have limitations of two-parameter models; rainfall amount and duration must be provided before model can be evaluated. However, the other empirical models are based on one parameter such as Time of Concentration (Duration) or Return Period, which is more convenient in evaluating intensity models than two parameters. These models relate the field data very well as shown in their high coefficients of correlation of between 0.869 and 0.998. The models were used to produce rainfall intensity values for the cities of Enugu, Owerri, Onitsha, Benin City, Warri and Port Harcourt.