HISWA

HISWA is a model to be used for the simulation of wave generation, propagation and dissipation in coastal areas.

Data on wave conditions is often available offshore but not nearshore. Accurate on site wave data is crucial in studies into coastal development, harbour design or breakwater design. HISWA is a wave generation and propagation model which can be applied to derive the wave conditions in the nearshore area. HISWA is also suitable for use as a wave hindcast model in water of intermediate and shallow depth for situations where the wind field may be considered constant. Typical areas for the application of HISWA range between 10 X 5 km2 and 30 X 100 km2 (e.g. along a coastal strip).

HISWA represents the wave field on a two dimensional horizontal rectangular grid covering the computational area. At each grid point the energy ( strictly 'action') in a number of direction sectors is predicted, thus discretely representing the directional spectrum of the wave field. The wave frequency spectrum is represented parametrically in each direction sector and at each grid point. The solution technique marches forward row by row over the grid beginning at the incident wave boundary, where the incident wave characteristics (height, period, main direction and directional spreading) can be defined. The results in each direction sector at each grid point are computed from the results for the grid points in the previous row. The propagation of energy is modeled using an energy balance equation adapted to include terms for wave growth by wind action or dissipation due to bottom friction or wave breaking.

HISWA assumes a uniform wind field and a stationary situation. This requires that the time scale of wave propagation through the computational area is short compared to the time that waves take to cross the computational area. HISWA was developed by the Delft University of Technology, and has been verified using results from both field measurements and from physical model tests.

HISWA is suitable for use on PCs, mainframes and super-computers with vector processors.

© 2001Alkyon Hydraulic Consultancy & Research, The Netherlands.