Annual and seasonal trends in extreme precipitation events in the dry zone of Sri Lanka

Abstract

Extreme precipitation events can be devastating, especially in countries heavily reliant on agriculture. In Sri Lanka, where agriculture is predominantly influenced by the dry zone, studying trends in precipitation extremes is crucial for enhancing resilience and mitigating adverse impacts. The objective of this study is to examine the annual and seasonal trends in extreme precipitation events within the dry zone of Sri Lanka. Daily precipitation data from 19 selected locations within the dry zone, spanning 38 years from 1981 to 2019, were analyzed. Thirteen extreme precipitation indices were computed using the RClimDex software package and Microsoft Excel, following the guidelines established by the expert team on climate change detection and indices (ETCCDI). Regression analysis and Mann-Kendall tests were conducted to assess trends in annual and seasonal extreme precipitation events. This study, which utilized more recent data, identified significant (p < 0.05) trends in both annual and seasonal precipitation indices. Seven locations exhibited a significant (p < 0.05) positive trend in annual total precipitation (PRCPTOT), mainly attributed to variations in the number of rainy days. While precipitation during the Yala season remained consistent in many locations, a decrease in drought events was observed. During the Maha season, Anuradhapura, Batticaloa, Okkampitiya, Wellawaya, Trincomalee and Polonnaruwa showed significant positive trends for flood-related indices indicating a decrease in drought occurences during the season.