In Detail: Use of Elevation Data for Storm Surge Coastal Flood Modelling

Risk management of storm surges requires knowledge on the temporal and geographic characteristics of storm surges, i.e. storm surge hazard maps; and information on the type of elements which are exposed and their vulnerability. Due to their strong wind speeds at sea, tropical storms or cyclones often generate storm surges that affect coastal communities when they reach land. The coastal inundation triggered by storm surges depends on the strength of the tropical cyclone and local conditions (bathymetry up to the coast and elevation above sea level). The presence of infrastructure, as well as estuaries and other coastal bodies may also play a role in the geographical extension of the coastal flooding. Often, high resolution data on bathymetry in coastal areas may not be available. So, it is not possible to use traditional hydraulic models to elaborate a precise estimation regarding coastal flooding in a specific area of a coast. In addition, in many developing countries there is no systematic record of the geographical extent of inundation of coastal areas due to storm surges which could be used to develop a statistical model. Therefore, high-resolution Digital Elevation Models (DEM) may be used as a first approximation to model the potential geographical extent of such coastal flooding. This Recommended Practice allows users to visualize the geographical extent of coastal flooding or sea level rise on local, regional or global scale (depending on the resolution and accuracy of the incoming digital elevation model). The combination of the results of this Recommended Practice with data on the location of exposed elements, their degree of vulnerability and fragility can be used for an initial estimation of risk and to elaborate potential scenarios of impact of storm surges in specific geographic locations in coastal areas.