ANALYSIS OF PRECIPITATION ANOMALY INDICES FOR EXTREME RAINFALL OVER THE IRANAIMADU TANK IN SRI LANKA

Abstract

The extreme rainfall events leading Kilinochchi district which has Iranaimadu tank is a major water source, to droughts and floods prone. The objective of this study is to analyse temporal variation of extreme rainfall events over the Iranaimadu tank. This study used thirty years (1984 – 2018) of monthly rainfall data. The study used Precipitation Anomaly Index (PAI) to identify extreme rainfall events. The extreme events showed drought events (PAI ≤ 1) and flood events (PAI ≥ 1). The data analysis done by descriptive analytical technique. Results revealed that annual extreme events were noted 23 events (76.7 %) including 15 drought events and 08 flood events. Seasonal extreme events were noted 86 events (71.7 %) such as 48 seasonal drought events and 38 flood seasonal events. High monthly drought events recorded in June and flood events noted in November. Droughts are a significant extreme events. Hence decision makers should give priority to drought mitigation.