Non-stationary analysis of extreme rainfall in Peninsular Malaysia

Abstract

Mean and variability of annual and seasonal rainfall in Malaysia are changing due to climate change. The estimation of the return period of extreme rainfall events based on stationary assumption may therefore not be valid in the context of climate change. Estimation of return period of extreme rainfall events for Peninsular Malaysia considering the concept of non-stationary is urgent for the mitigation of flood impacts and adaptation to climate change. This study estimated non-stationary return periods of extreme rainfall events in different locations of peninsular Malaysia using hourly rainfall data. Augmented Dickey-Fuller test assessed the stationary in time series. The extreme rainfall time series were fitted using generalized extreme value distribution and the fitted distribution parameters were estimated using maximum likelihood estimator. The results of 1-, 2-, 3-, 10-, 12-, 24-, 48- and 72-hour at 2-, 10-, 25-, 50-, 100-year return periods at most of the stations showed an increase in maximum rainfall amounts. The highest significant increase was found in Kelantan at 7.62 mm/year for the 72-hour extreme rainfall amount. The maps of the spatial distribution of the non-stationary rainfall amount for different return periods can be helpful for a better design of the hydraulic structure.