Extreme value analysis of annual maximum rainfall data in Colombo and Anuradhapura

Abstract

Sri Lanka experiences various natural disasters like floods and landslides, where extreme rainfall is a major contributory factor. In relation to climate change, a crucial question also arises about the possible variability of these extremes. In this study, annual maximum daily rainfall data recorded at Colombo (1901- 2013) and Anuradhapura (1889-2005) meteorological stations from the wet and dry zones respectively are analysed. The major objective of this research is to obtain the best fitting probability distribution for the data, considering the Gumbel, Log normal and Log Pearson type III distributions. From the analysis, rainfall of 25, 50 and 100 year return periods have been estimated. These results have been compared with the values given by the Irrigation Department of Sri Lanka and used in design work. The results of this study are useful for future work related to flood control, disaster management and water resources planning.