Due to climate change and an expansion of urban catchment, urban flooding is becoming a major environmental hazard and can cause very costly damages to properties and assets around Australia. The insurance industry is in real need of accurate information for their use in risk analysis and urban flood vulnerability.
Innovation and technologic improvement in the acquisition technics and the processing of digital elevation models can make it economically feasible to gather large and accurate 3D information of natural and urban areas.
Detailed modelling and analysis of urban flooding requires a good knowledge of natural terrain features as well as urban surfaces and man-made objects in term of rainfall-runoff and surface flow. Lidar is commonly used as 3D information input for these flood models but recent advances in digital aerial photogrammetry allow the creation of very accurate digital surface models in addition to the high resolution imagery.
The following video gives an example of a 3m raising water level over a residential area near Melbourne showgrounds (Ascot vale). A 3cm digital aerial photo capture has been used to generate a perfectly seamless mosaic and a 20cm digital surface model of the area.
Better Flood Insurance Rate Maps are critical for the insurance industry to get information on levels of risks and high resolution accurate digital surface models generated from aerial photogrammetry is a big part of the solution.