Extreme river behaviour in the Pacific Islands - Case studies from Samoa and Fiji

Abstract

Tropical cyclones are important for generating extreme river floods in Samoa and Fiji. In the Vaisigano and Rewa rivers, floods are large, brief, isolated events. Large floods are the result of torrential TC precipitation intensities coupled with the environmental characteristics of mountainous volcanic island river basins which promote hydrological short-circuiting and rapid runoff. Flood discharge is augmented when TCs travel along the length of a watershed. Peak flows produced during TCs are inversely correlated with the SOI. The log Pearson Type III distribution provided good fits to measured data of maximum discharges, but the popular generalized Pareto distribution performed poorly. This work continues to increase our knowledge of hydrology in tropical Pacific island environments, where the behaviour of fluvial systems remains poorly understood.