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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Poster presentation 1824
How very-high resolution 3D DEM contribute to quantitative tsunami
damage forecast: the study case of Sri Lanka
Dr. Alberto Armigliato
Dipartimento di Fisica, Settore Geofisica Universita di Bologna IASPEI
Stefano Tinti, Fabrizio Ferrucci, Roberto Tonini, Sara Gallazzi, Gianluca Calabretta
Tsunami damage assessment and forecast requires both sophisticated numerical modelling and support
of data sets reflecting our knowledge of the physical coastal environment and of the socio-economic
values exposed to the risk. The problem is complex and no standard methodology has been so far
introduced to make quantitative assessment and to provide local communities and responsible
authorities with basic agreed-upon tools to make quantitative estimates of tsunami impact. Here we
explore the contribution that very-high resolution 3D mapping from airborne and spaceborne techniques
may give to quantitative estimates resulting from tsunami modelling. The area of application is Sri-
Lanka, that was severely hit by the 26th December 2004 distastrous tsunami of the Indian Ocean, that
killed more than 290,000 people, and in Sri Lanka took a fatality toll of more than 30,000. This paper is
based on the data provided by the project HyperDEM, that was born from an inter-Governmental
agreement established between Italy and Sri Lanka and was funded by the Italian Ministry for Foreign
Affairs. The project work was mainly based on the integration of airborne LiDAR and spaceborne RaDAR
campaigns that were undertaken between autumn 2005 and summer 2006. The post-processing data
products are a Digital Ground Model (DGM) and a Digital Surface Model (DSM). DGM represents the
Earth elevation cleaned of vegetation and manufacts and it is suitable for mapping the water
penetration in vegetated areas with little presence, or absence, of manufacts, while DSM includes them
and it is indicated for a detailed inundation mapping in urban areas. The terrain resolution in some
urban areas was of 1 metre, providing a very detailed topography which, if properly combined with an
accurate bathymetric data set, is well suited to the computation of detailed inundation map by means of
numerical models. In this study we concentrate on the city of Galle, placed along the south-western
coast of Sri-Lanka, where more than 4,000 persons were killed by the 2004 tsunami and the quay was
completely destroyed. We consider tsunami simulations models where use is made of high-accuracy 3D
DEM and discuss uncertainties in tsunami inundation maps resulting from combination of data with
different level of accuracy and different resolution (see coastal DEM compared to offshore and nearshore
lower-accuracy bathymetric data).
Keywords: high resolution dem, tsunami inundation, tsunami damage