tsunami propagation and flooding simulation with Delft3D

The fourth largest earthquake in this century with an epicenter off the coast of Aceh (North Sumatra) awoke the world on the 26th of December 2004 at 00:58 UTC. Being closest to the epicentre, the coastal areas in the Northern part of Sumatra were hit almost immediately by the largest waves with devastating effects. Most of the damages and death toll was caused by the unexpected attack of the tsunami flood waves. What happened?

Deltares has set-up an accurate Delft3D model to compute the propagation of the tsunami using an appropriate initial condition. The results were compared with relative sea level heights measured by the four radar altimeter satellite that recorded the running tsunami wave in the Indian Ocean . The data was provided by E. Schrama from the Technical University of Delft.

comparison of simulation results with satellite altimeter data

Four radar altimeters coincidentally happened to observe sea level height profiles over the Indian Ocean during the first few hours after the earthquake. TOPEX/Poseidon and Jason-1 satellite mapped the Indian Ocean about 2 hours after the tsunami started; Envisat satellite saw the tsunami at 3 hours 15 minutes and the US Navy GEOSAT follow-on satellite (GFO) saw the wave more than 7 hours after it started.

In the figures below one can observe the computed and observed sea level. The observed data are presented as black dots and the computed levels are presented as continuous line. Similar comparison was carried out in the past with the MOST tsunami prediction model run by NOAA.

flooding in Aceh, Sumatra ( Indonesia )

A high resolution nested model of Aceh is applied to simulate the flooding. For the flooding simulations the “flood” scheme, which was recently incorporated in the Delft3D system, has been applied.

The figures below shows the computed flooded area in the coastal region of Banda Aceh. The satellite picture taken by IKONOS satellite show that the model has reproduced the flooded areas extremely well.

The simulated maximum tsunami wave heights at a number of locations were compared with the survey data that was compiled by the International Banda Aceh Tsunami Survey Team. In the Northern coast of Aceh the simulated heights are in good agreements with the data.

use of models within an early warning system

The CPU-time required on a 3.8 GHz PC for the propagation model for a six hour simulation period equals approximately 10 minutes. Consequently, integration of these models within an early warning system is already feasible or will become feasible within a very near future.

more information

capability statement: Tsunami propagation and flooding (in PDF)

For more information contact Deepak Vatvani.