Estimation of flood mitigation parameter for Tiruchirappalli city using Mathematical Relational Model

Abstract

Intensity Duration Frequency (IDF) curve is a mathematical tool used for generating rainfall depth characteristics for various return periods. It is a critical parameter for analyzing extreme events such as floods in urban areas. IDF curves are needed in the planning and design of useful urban drainage structures. The objective of this investigative study is to develop IDF curves for the observed rainfall conditions in the city of Tiruchirappalli, located in the southern state of Tamil Nadu, India. The trends of the intensity, duration and return periods of rainfall are statistically analyzed by Gumbel, Log Pearson Type III, and Log-normal distribution methods for five rain gauge stations situated in the city, from 1976 to 2016 and tested for goodness-of-fit. The Chi-square and Kolmogorov – Smirnov techniques are the goodness-of-fit tests used to determine the best fit. The constant mitigation parameters for the five stations are calculated by the distribution methods, and it is found that the Gumbel distribution method is an appropriate one to predict flood inundation reliably. The rainfall intensities are obtained from this method, and isopluvial maps are generated for different durations and return periods. The results obtained will serve as valuable information for the planning and management of drainage structures in Tiruchirappalli and help avoid future flood disasters.