FAQ/ Is the shallow-water equation used?¶
Does DioVISTA use shallow water equations?
Yes, it is used.
A two-dimensional shallow-water equation is used for the flood model and a one-dimensional shallow-water equation is used for the river model.
The shallow water equations are the Navier-Stokes equations equations) is an equation obtained by integrating vertically. The term shallow-water equation is widely used in atmospheric and aerophysical and coastal engineering, and in river engineering it is often called the Saint-Venant equations, two-dimensional indefinite flow equations, and one-dimensional unsteady flow equations. Therefore, DioVISTA uses the terms two-dimensional indefinite flow equation and one-dimensional irregular flow equation.
In the shallow water equation, the water level and flow velocity are the main variables, but the factors that should be considered in the ocean (ocean wind, Coriolis force), etc., the factors that should be considered in flood flow (handling of the boundary between inundation and non-flooding, etc.) and the factors that should be considered in rivers (cross-sectional shape of the river channel, confluence, etc.) are different. Therefore, even if it is also called the "shallow water equation", the actual equation may differ depending on the field of application.
For more information, see the technical references Flood Model - Basic Formula and River Channel Model - Basic Formula.