A SHALLOW WATER MODEL FOR COMPUTING TSUNAMI ALONG THE WEST COAST OF PENINSULAR MALAYSIA AND THAILAND USING BOUNDARY-FITTED CURVILINEAR GRIDS

The west coast of Peninsular Malaysia and Thailand is curvilinear in nature and the bending is especially high along the coast of South Thailand. In hydrodynamic models for coastal seas, bays and estuaries, the use of boundary-fitted curvilinear grids not only makes the model grids fit well with the coastline and bathymetry, but also makes the finite difference scheme simple. In this study, a shallow water model is developed using boundary fitted curvilinear mesh. The west coast of Peninsular Malaysia and Thailand and the western open boundary are represented by two curves, which are defined by two functions. The other two boundaries are considered as straight lines along the open sea. Appropriate transformations of independent coordinates are applied so that the curvilinear physical domain transforms to a rectangular domain and the curvilinear grid system transforms to a rectangular system. The depth averaged shallow water equations and the boundary conditions are transformed to the new space domain and these are solved in the rectangular mesh of the transformed space. The model is applied to compute some aspects of the tsunami associated with the 26 December 2004 Indonesian tsunami along the coastal belts of Penang in Malaysia and Phuket in Thailand. The computed results along the coastal belts are in excellent agreement with the observe data available in the USGS website.