Moving Boundary Numerical Surge Model

This paper adopts the time-split explicit (TSE) finite difference technique to simulate the storm surge on the vertically integrated hydrodynamic equations of continuity and momentum. The unique feature of the present model lies in its treatment of water-land interfaces as moving boundaries (MB). The conventional assumption of fixed boundary (FB) with a vertical wall located at the water-land interface of mean sea level is completely discarded. In the present model the advancing and retreating of the surge wave over the low-lying dry land and the propagation of the water-land interface are dealt with on the basis of physical and mathematical principles. Numerical experiments indicate that the MB model predicts lower surge level at the coast line as much as 30% than the FB model when the adjacent inland area has a mild slope and the wind is very strong. The MB model yields better agreement with recorded surge than the FB model, which consistently over-predicts the surge elevations.