Title: Terrain Modelling to Support Flood Disaster Mitigation in Urban Areas Using Photogrammetry and Lidar
Citation: Proceedings of the Annual Conference of the Remote Sensing and Photogrammetry Society RSPSoc
Publisher: The Remote Sensing and Photogrammetry Society
Publication Year: 2006
JRC N°: JRC34192
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC34192
Type: Articles in periodicals and books
Abstract: Flood disasters are causing 40 % of the damages globally each year. Most serious problems are related to urban flooding due to the fact that human populations are likely settled in flood prone areas. Accumulating valuable possessions on floodplains carries a great risk of damage to property and excessive threat in loss of life. To mitigate the impact of these catastrophes hazard and vulnerability of property and human life has to be analysed in advance, before the disaster strikes. The crucial input of flood extent modelling is the information on the elevation of the study area. The quality of hydraulic model outputs may benefit from an accurate description of the terrain surface. For this reason an investigation was done on the possibilities to perform terrain modelling using remote sensing surveying techniques in build-up areas. An investigation was made on two major data sources of 3D surface modelling to serve as an initial input for flood modelling. In a first step the latest methods of airborne remote sensing was explored. Laser altimetry (LIDAR) was compared with the typical photogrammetric solution of image matching using aerial photographs in urban area. In a second step the space-borne radar altimetry was investigated (SRTM) to explore the possibilities of a global data set additionally to the two local surveying methods. Airborne data sets were surveyed by the Unit for Landscape Modelling, at the University of Cambridge over the town of Cambridge. Post-processing was done to acquire digital surface models in the study area. Image matching of stereo aerial images and filtering of LIDAR data points was performed to obtain spatial elevation information on the urban area. Radar altimetry was processed using interferometry 3D mapping techniques to acquire the most complete high-resolution digital topographic database of the Earth. Resulting digital surface models were compared in their performance to describe build-up areas. The great elevation differences between rooftops and streets in the city centre was found to be poorly reflected in photogrammetric results whereas geometrical shadowing of the pulse were causing information leak of the same area using laser surveying. Further one-dimensional steady state hydraulic simulation was performed for a section of the River Cam in Cambridge to compared typical advantages and disadvantages related to the different surveying methods in build-up areas concluding in the applicability of the data sets for hydrological modelling.
JRC Directorate:Space, Security and Migration

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