Robust Shallow Water Equation Model for Tsunami Disaster Management

In recent days, lot of focus has been given to the modelling of tsunami in global scale to compute the run-up height and arrival time of tsunami around the coastal locations. The propagation of tsunami in the ocean is a complex process, coupled with wind generated waves, internal waves, tides, etc. Among various additional forces tide forcing is expected to play a major role in the computation of tsunami run-up height. Tidal elevation along the coast can amplify or abase the run-up height. More thrust needs to be given to the tide-tsunami interaction to better understand the computation of landfall heights. This will help in defining a more accurate and reliable plan for mitigation measures. This study presents the effect of tide on the propagation of tsunami and the resulting landfall heights. The tide and tsunami are governed by Shallow Water Equations (SWE). Thus, the whole system could be simulated by discretising the single set of SWE. In the present case, depth averaged 2-dimensional Shallow Water Equations (SWE) were solved for the investigation of tide-tsunami interactions by computing the primitive variables.

The tsunami is always coupled with perennial tide in the real events. The tidal variation can lead to amplification or moderation of tsunami landfall heights. An attempt has been made to study the effect of tide on tsunami. The tsunami was forced into a domain with fully developed M2 tide. The tsunami was generated with and without the tidal forcing to observe the difference in landfall heights near the coast. It is observed that the tidal forcing has resulted in an altered landfall height at the shelf. The nonlinear interaction between the tide and tsunami is investigated in the present study that provides robust prediction of the tsunami height and landfall time.