Tsunami propagation and flooding
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View from space at 26th December, 2004, 02.00 UTC Deltares/Delſt Hydraulics has carried out numerical experiments to better understand the dynamics of tsunami generation, propagation and flooding and to support the restoration efforts of habitats (coral reef, mangroves, wetlands and coastal (infra) structures). This forms an essential part of the risk and safety assessment for the disaster stricken area and the development of future flood hazard maps. The basis of such a risk assessment is a modelling framework that is relatively accurate, robust and computationally efficient. Set-up of an accurate Delſt3D model To compute the propagation and flooding of the tsunami a Delſt3D model has been set-up for Aceh – Sumatra. The initial water surface displacement was estimated from reverse modelling. The results of the computation were compared to relative sea level heights measured by the four radar altimeter satellite that recorded the running tsunami wave in the Indian Ocean on December the 26 th 2004. This was done with data provided by the Aerospace Engineering Department from the Technical University of Delſt, Mr E.J.O. Schrama. Comparison of simulation results with satellite altimeter data Four radar altimeters observed sea level height profiles over the Indian Ocean during the first few hours aſter the earthquake. TOPEX/Poseidon and Jason-1 mapped the Indian Ocean about 2 hours aſter the tsunami started; Envisat recorded the tsunami at 3 hours 15 minutes and the US Navy GEOSAT follow-on satellite (GFO) recorded the wave more than 7 hours aſter it started. Comparison between modelled water surface elevation and satellite observations shows good agreement between the two. Tsunami propagation and flooding An earthquake with a magnitude of 9.3 occurred on 26 th December 2004 at 00:58 UTC with an epicentre off the coast of Aceh (North Sumatra). The subsequent tsunami that ravaged the Indian Ocean took an enormous toll on human life and caused immense damage along the coastal areas in India, Andaman Islands, Thailand, Sri Lanka and Indonesia. 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 damage and death toll was caused by the unexpected attack of the tsunami flood waves.
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An earthquake with a magnitude of 9.3 occurred on 26th December 2004 at 00:58 UTC with an epicentre off thecoast of Aceh (North Sumatra). The subsequent tsunami that ravaged the Indian Ocean took an enormous tollon human life and caused immense damage along the coastal areas in India, Andaman Islands, Thailand,Sri Lanka and Indonesia. Being closest to the epicentre, the coastal areas in the Northern part of Sumatrawere hit almost immediately by the largest waves with devastating effects. Most of the damage and death tollwas caused by the unexpected attack of the tsunami flood waves.
Transcript of Tsunami propagation and flooding
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View from space at 26th December, 2004, 02.00 UTC
Deltares/Delft Hydraulics has carried out numerical experiments to better understand the dynamics of tsunami generation, propagation and flooding and to support the restoration efforts of habitats (coral reef, mangroves, wetlands and coastal (infra) structures). This forms an essential part of the risk and safety assessment for the disaster stricken area and the development of future flood hazard maps. The basis of such a risk assessment is a modelling framework that is relatively accurate, robust and computationally efficient.
Set-up of an accurate Delft3D modelTo compute the propagation and flooding of the tsunami a Delft3D model has been set-up for Aceh Sumatra. The initial water surface displacement was estimated from reverse modelling. The results of the computation were compared to relative sea level heights measured by the four radar altimeter satellite that recorded the running tsunami wave in the Indian Ocean on December the 26th 2004. This was done with data provided by the Aerospace Engineering Department from the Technical University of Delft, Mr E.J.O. Schrama.
Comparison of simulation results with satellite altimeter dataFour radar altimeters observed sea level height profiles over the Indian Ocean during the first few hours after the earthquake. TOPEX/Poseidon and Jason-1 mapped the Indian Ocean about 2 hours after the tsunami
started; Envisat recorded the tsunami at 3 hours 15 minutes and the US Navy GEOSAT follow-on satellite (GFO) recorded the wave more than 7 hours after it started.
Comparison between modelled water surface elevation and satellite observations shows good agreement between the two.
Tsunami propagation and flooding
An earthquake with a magnitude of 9.3 occurred on 26th December 2004 at 00:58 UTC with an epicentre off the coast of Aceh (North Sumatra). The subsequent tsunami that ravaged the Indian Ocean took an enormous toll on human life and caused immense damage along the coastal areas in India, Andaman Islands, Thailand, Sri Lanka and Indonesia. 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 damage and death toll was caused by the unexpected attack of the tsunami flood waves.
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Deltares - Tsunami propagation and flooding2
The computed spreading
of the tsunami energy.
Computed and observed tsunami wave heights along the TOPEX/
Poseidon and Envisat satellite tracks at: a. T+2:00 UTC (left) and b. at
T+3:15 UTC (right). Red line denotes the tracks of the satellite.
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Deltares - Tsunami propagation and flooding 3
Flooding in Aceh, Sumatra (Indonesia)A high resolution nested model of Aceh was applied to simulate the coastal flooding as a result of the tsunami waves. Details of the bathymetry on land were resolved using the 90 m resolution Digital Elevation Model (DEM) of the Shuttle Radar Topographic Mission (SRTM). Comparisons of the modelled results were made with survey data and flooding pictures made from satellite.
For the flooding simulations the flood scheme of the Delft3D system has been applied. This scheme combines the efficiency of staggered grids with conservation properties to ensure accurate results for rapidly varying flows. The figure below shows the computed flooded area in the coastal region of Banda Aceh. The results match the flooding pictures taken by satellite extremely well. The simulated maximum tsunami wave heights at a number of locations were compared with the survey data as shown in the table below.
Simulated flooded area in Banda Aceh; an overview (left) and a detail
view for Banda Aceh (right).
C
A
B
A B
C
Comparison of observed and computed tsunami arrival times at
Boxing day. 2004.
Use of the tsunami models It has been used for generation of (under the Sea Defence consultants project funded by the Royal Netherlands Embassy, together with the DHV Group and Witteveen+Bos consultants) of: Coastal flood risk maps; Tsunami warning system; and Hind cast of past tsunami events to determine coastal vulnerability
Related studies and projects Deltares/Delft Hydraulics has performed related studies and projects in: St. Petersburg, Russia: A flood warning and assessment GIS; Andhra Pradesh, India: A cyclone hazard mitigation project; real time early warning modelling system; Vietnam: Development and transfer of an operational semi-automatic typhoon-induced storm surge forecast system. Willapa Bay, WA, USA (in conjunction with the USGS): comparing the effects of tsunami and subsidence on the long-term morphology of the bay; and Tsunami benchmark studies.
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P.O. Box 1772600 MH Delft, The [email protected]
For more information contact:Deepak Vatvani orJohan Boon
