Regional frequency analysis of maximum daily rainfalls using TL-Moment approach

Abstract

Analyzing rainfalls data are important in order to obtain the probability distribution of flood. The main aim of the study is to perform regional frequency analysis of maximum daily rainfalls measured over stations in Selangor and Kuala Lumpur by using the TL-moment method with t = 0, t = 1 and t = 2. Initially, the maximum of each daily rainfall for each year were obtained. Then, parameters of every distributions considered including the normal (N), logistic (LOG), generalized logistic (GLO), extreme value type I (EV), generalized extreme value (GEV) and generalized Pareto (GPA) distribution were estimated using TL-moment approach. TL-moments with t = 0 are known as L-moments while TL-moments with and imply TLmoments that are symmetrically trimmed by one and two conceptual sample values respectively. The most suitable distribution were determined according to the mean absolute deviation index (MADI), mean square deviation index (MSDI) and correlation, r. L-moment and TL-moment ratio diagrams provided visual proofs of the results. The L-moment method showed that the generalized logistic (GLO) distribution is the best distribution whilst TL-moment method with t = 1 and t = 2 concluded that the extreme value type I (EV) and generalized extreme value (GEV) distributions are the most suitable distributions to fit the data of maximum daily rainfalls for stations in Selangor and Kuala Lumpur.