Channel Routing

Channel routing deals with unsteady flows. Unsteady flows are flows that change relative to time. Hydrographs are an excellent example of unsteady flows. The storage in the channel has a major impact on hydrographs by reducing the peaks and redistributing the hydrograph volume. Factors impacting the shape of the hydrograph are channel slope, roughness and shape as well as available storage between two points along the channel.

If the channel is steep, prismatic, smooth with little storage and no immediate inflows, the outflow hydrograph from the channel would look very similar to the inflow hydrograph except for a time lag equal to the travel time between the upper and lower end. However, for flat, irregular shaped, hydraulically rough channels with much storage capacity available, the outflow hydrograph would be attenuated. Its peak would be decreased, and volume redistributed.

Channel routing based on the continuity equation is known as hydrologic routing. There are several hydrologic routing methods, Storage, Muskingum-Cunge, Convex, and Kinematic are among them. On the other hand, routing based on both momentum and continuity equations are known as hydraulic routing. They typically require a numeric solution. StormShed3G™ supports the following hydrologic routing methods. Of the routing methods supported by StormShed3G™, the Muskingum-Cunge is probably the most stable method. It is currently the preferred channel routing method.