Selection of best fit probability distribution for extreme value analysis of rainfall

Extreme Value Analysis (EVA) of rainfall is considered as one of the important aspects to arrive at a design arameter for planning, design and management of civil and hydraulic structures. This can be carried out by fitting probability distributions to the observed annual maximum rainfall series wherein the parameters of the distributions are determined by method of moments and Maximum Likelihood Method (MLM). In this paper, a study on evaluation of Extreme Value Type-1 (EV1), 2-parameter Log Normal (LN2) and Log Pearson Type-3 (LP3) distributions adopted in EVA of rainfall for Anakapalli, Atchutapuram, Kasimkota and Parvada sites is presented. Goodness-of-Fit (viz., Chi-square and Kolmogorov-Smirnov) and diagnostic (viz., root mean squared error) tests are used to evaluate the performance of probability distributions adopted in EVA of rainfall. Based on GoF and diagnostic tests results, the study identifies the LP3 (MLM) is better suited probability distribution for EVA of rainfall at Anakapalli while LN2 (MLM) for Kasimkota and EV1 (MLM) for Atchutapuram and Parvada.