Using raster DTM for dike modelling

Abstract

Digital Terrain Models are necessary for the simulation of flood events. Therefore they have to be available for creating flood risk maps. River embankments for flood protection have been in use for centuries. Although they are artificial structures that actually do not belong to the natural elements of the land surface they are usually implicitly embedded in digital terrain data. Being elongated and elevated objects, they appear - depending on the used colour ramp for visualisation - as bright stripes on the surrounding background. For purposes of flood protection it might be useful to gain data about crest levels, especially if these information are not available from other sources. High resolution Digital Terrain Models (DTM) can be used as highly reliable sources for deriving dike heights. Using laser scanner technique a general height accuracy of about 10-15 cm can be achieved for elevation models. Thus, by analysing DTM data relevant geometrical information on dikes can be directly derived.