Wave, Tide, and Tsunami Flooding

Wave, tide, and tsunami flooding can occur due to rising sea levels during extreme high tides, the propagation of long waves from distant sources, and tsunami events. Extreme high tides may inundate coastal and nearshore lowland areas for a certain period, usually between two and five days, depending on the local tidal regime and land topography. Inundation depths caused by tidal flooding may reach approximately 1 to 2 meters.

Long waves generated from distant sources, such as Kelvin waves, Rossby waves, and internal solitary waves, may also cause flooding in low-lying and gently sloping coastal areas. In some cases, internal solitary waves can create more significant impacts due to their high wave energy. When these waves reach the coast, their height may range from approximately 1 to 3 meters and may penetrate farther inland along flat and low-lying coastal plains. The propagation of internal solitary waves can often be clearly observed using satellite radar imagery, which can detect wave patterns and sea surface variations in offshore waters.

Tsunami flooding is generally caused by undersea earthquakes and may produce severe impacts due to the very high energy and propagation speed of tsunami waves. However, not all undersea earthquakes generate tsunamis. Tsunami generation depends on the earthquake magnitude, focal depth, and the amount of seabed deformation. Wave heights near the earthquake source are generally smaller than the wave heights observed near the coast. As tsunami waves approach shallow coastal waters, their height increases due to changes in seabed topography and decreasing water depth. Tsunami inundation depths may range from 1 to 5 meters or even higher. However, the inundation period is usually relatively short because the water that enters the land returns to the sea within a short period as the system seeks equilibrium.

The hydrodynamic module is used to simulate tidal flooding and tsunami propagation. It can also accommodate wave flooding caused by distant long-wave sources such as Kelvin waves, Rossby waves, and internal solitary waves for large-scale model domains. Initial conditions related to sea level changes can be detected using radar imagery. Internal solitary waves are formed by water mass movement driven by variations in temperature, salinity, and pressure within the water column. These waves may develop when water masses move into shallow waters or narrow straits. Changes in temperature, salinity, and pressure can also be simulated using this module.