Run-Up means the process of a Tsunami wave entering often very shallow coastal waters and the propagation further inland. In this process, the wave may be subject to essential transformations, e. g. the steepening of the wave to a multiple of the height in the open ocean, or breaking, where the water masses continue to propagate in the form of a bore. The characteristics of the coastal area play an important role in this. The wave transformations determine the velocity at which and up to what elevation line the water advances inland. This is of major importance for the planning of protective measures, including the evacuation of population.
Some phenomena cannot be mathematically described by the aforementioned non-linear shallow water equations used in the open ocean modelling. For example, to capture the splitting of the wave into different frequencies or the generation of an undulating bore, the Boussinesq equations are used. In comparison to non-linear water equations, these are comprised of additional terms of an equal or higher order (see as an example, the model result of a test simulation in the figure below). This type of simulation is very computationally intensive, as a high spatial requirement (in the order of 100m or less) is required to map the coastal properties, the topography and the tsunami signal. For this reason, the strategies developed by the GITEWS participants at the Geesthacht Research Centre and DHI Water & Environment will concentrate on a few selected areas with the MIKE 21 HD and MIKE 21 BW modelling systems. Areas will be studied that are characterised by high vulnerability, typical coastal geometries, water depths and steep ground slopes. The scenarios of AWI's TsunAWI ocean model will also be applied.
The results of the scenarios themselves will be combined into hazard maps. In combination with data regarding population density, building substance and road routing, they serve as a basis for evacuation maps, which show safe zones and evacuation routes.