The Exceptional Flooding on Vanua Levu Island, Fiji, during Tropical Cyclone Ami in January 2003

Abstract

In mid-January 2003 Tropical Cyclone Ami passed directly across the Fiji Islands in the southwest Pacific Ocean. The main northern island of Vanua Levu experienced torrential rainfall and consequent record-breaking flooding of its major rivers. The aims of this study were to document these record floods and compare them with previous floods on Vanua Levu Island. The Nasekawa River in southern Vanua Levu produced a phenomenal discharge of more than 6100 m 3 /s. Moreover, near the main town of Labasa on the north coast, simultaneous flooding of the Labasa, Qawa, and Wailevu rivers combined with storm surge to cause inundation of up to 4 m depths over a wide area of the floodplain. Tragically, seventeen people died, and there was extensive damage to farms, the infrastructure, homes, and commercial property. Historically, the north coast of Vanua Levu island has suffered frequent severe floods, owing to several factors: 1. the approach of most tropical cyclones towards Fiji from the northwest; 2. Vanua Levu’s steep volcanic topography, which rises in excess of 1000 m, and has strong orographic influence on rainfall generation during tropical storms, then rapidly transfers moisture into river channels, 3. the configuration of several drainage basins which deliver floodwaters to the same area of the coastal hinterland. Future regional ocean warming and more sustained El Nino conditions are projected to increase the intensity of tropical cyclones and thereby the potential for worse flood disasters. Disaster mitigation and adaptation options recently proposed by the World Bank and JICA need to be implemented to reduce flood impact in this vulnerable area of Fiji.