Although coastal flooding by far is caused by hurricanes and similarly severe storm events, underwater earthquakes may also trigger tsunami waves which in turn can cause similar damages and casualties. Traditionally two dimensional models have been applied for coastal flooding studies as the water column under such conditions often is well-mixed and thus well suited for MIKE 21 or alternatively MIKE Flood. A three dimensional approach will with few exceptions not add any additional information that justifies its use. The key issues in coastal flooding are often the maximum water depths, flood extent and timing of the flooding in the areas being affected such that proper  actions be taken to minimize both potential casualties and damages.

MIKE 21 has successfully been used for coastal flooding studies i hundreds of studies for more than 35 years. It is an extremely powerful and efficient tool regardless if the objective is hazard maps, impact assessments or operational warning systems.

In applications near the continental shelf and in presence of a strong, distinct stratification or buoyancy driven current it is often required to go for a three dimensional modelling approach.