UN-SPIDER: Recommended Practice | Use of Digital Elevation Data for Storm Surge Coastal Flood Modelling

Storm surges and tidal waves are global phenomena that considerably affect human populations in coastal and island regions.

According to the Guide to Storm Surge Forecasting published by the World Meteorological Organization in 2011, storm surges can be defined as “oscillations of the water level in a coastal or inland body of water in the time range of a few minutes to a few days, resulting from forcing from atmospheric weather systems. According to this definition, the so-called wind waves, which have durations on the order of several seconds, are excluded”. Storm surges are a coastal phenomenon triggered by strong winds in the oceans and seas due to tropical cyclones and other similar weather systems at sea.

Tsunami modelling, sea-level rise studies and storm surge hazard mapping have been done using deterministic and probabilistic models. However, deterministic models require precise oceanographic data, as well as data on bathymetry in the coast, coastal geometry and high-resolution digital elevation models in the coastal area and ancillary data on surface roughness in coastal areas. In many developing countries these data sets are not available.


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). It can be used exclusively as a first approximation to determine areas that are prone to inundation and can serve as a first assessment for further, more in-depth analysis of coastal flood and sea level rise assessment. The Recommended Practice is developed using the World Digital Elevation Model (WorldDEMTM) product of Airbus Defence and Space. For the sake of clarity – the Recommended Practice has not been developed for any other use and purpose than the above described one and is consequently not usable for and in navigation, any hazardous environment requiring error free performance.

Test Site: Larger Accra region, Ghana

The coastal region of Ghana was heavily affected by tidal waves in June 2017. Many people have been displaced and houses, infrastructure and fishing gear (boats, nets) have been destroyed. This Recommended Practice can be a first assessment to apply further analysis to identify safer ground for relocation of exposed communities.

Further information provided by the National Disaster Management Organization of Ghana (NADMO).

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Source: UNITED NATIONS Office for Outer Space Affairs (UN-SPIDER), June 2019