Development of Rainfall Intensity – Duration – Frequency (RIDF) Using Statistical Package for The Social Sciences (SPSS) as a Numerical Tool

Abstract

Information and adequate data on the intensity–duration–frequency of rainfall are regular requirements to reduce and correct variations in hydrologic, environmental and hydraulic applications, which are vital elements in Civil and Environmental engineering works. This paper focuses on the utilization of the Statistical Package for the Social Sciences (SPSS) as a numerical tool for the development of accurate Rainfall Intensity-Duration-Frequency (RIDF) equations for Makurdi, Nigeria as a follow-up to our previous studies. Rainfall intensities from Makurdi were used to establish empirically derived constants (C, m, n, and a) for three different Rainfall Intensity-Duration-Frequency equations. These equations were evaluated statistically (Analysis of Variance (ANOVA), total error, model of’ selection criterion (MSC), Coefficient of Determination (CD), Correlation coefficient (R) and Akaike Information Criterion (A IC), with the main objective of utilizing SPSS in the selection of the best equation for the location. The study revealed that C” ranges from 281.456 to 5160.64, “m” was between 0.446 and 0.577, “n” was in the form of -1.142 to 10.8887 and the value of “a” was between 14.486 and 52.793. The CD and R values for models A, B and C were 0.816, 0.854 and 0.8159, 0.903, 0.924 and 0.903 respectively. It was concluded that SPSS can be used as a numerical tool in the design of storm drains.