DEVELOPMENT OF A COUPLED WAVE AND STORM SURGE MODEL INCLUDING RIVER RUN-UP

Abstract

 Strong typhoons can cause storm surges and river floods. A simultaneous occurrence of both along estuaries will cause compound flooding. A numerical model representing the run-up of a storm surge into rivers is necessary for simulating compound floods. In this study, a coupled wave-surge model integrating river inflows was developed to consider the run-up of the storm surge into rivers. The model successfully simulated the storm surge and river water level in Yodo and Ina rivers during Typhoon Jebi (2018). Then, a series of sensitivity experiments on river inflow from the upstream were conducted. As a result, there was no significant difference in water level between coupled and uncoupled models near the river mouth. However, a maximum difference in water level up to 1.2 m at Kema (14 km upstream) was revealed. In addition, the peak time of water levels also changed between coupled and uncoupled models. Therefore, it is necessary to consider both a storm surge run-up and upstream water level to evaluate water levels in a river caused by storm surges and flooding in an estuary.