RIBASIM accepts basically any time step size. However, most basin simulations are executed on a:

• Monthly basis

• Half-monthly basis

• 10 days basis (decade)

• Weekly basis, or

• Daily basis

In most situations the selected simulation time is such that mass equations are used for the simulations. In situations that this is not valid RIBASIM offers various hydrologic channel and reservoir routing procedure, such as:

• The Manning formula.

• The flow - water level relation.

• The 2-layered, multi-segmented Muskingum formula.

• The Puls method.

• The Laurenson non-linear "lag and route" method.

Catchment of Tekeze River basin (Ethiopia)