Flood Routing

In addition to the full hydrodynamic solution techniques Flood Modeller also includes flood routing methods. Flood routing is used here to describe the process of determining the change in shape of a flow hydrograph as it moves along a channel without necessarily calculating water levels. Both the Muskingum and the Muskingum-Cunge flood routing methods are available and velocities can be estimated as a user-defined function of flow, for use in the Flood Modeller Water Quality model.

A particular feature of flood routing facility is the ABSTRACTION unit. This unit can act as a flow boundary or can be placed between a JUNCTION or RESERVOIR and flood routing units. It allows the user to specify rules for abstraction of water or reservoir operation. These rules may specify the abstraction or flows as a function of variables defined at any node in the model so that, for example, abstracted flow could be specified as a percentage of the base river flow. At each abstraction, a number of logical rules defined by Fortran-like 'if statements' may be specified and these rules can be applied as a time series. In this way the effects of abstraction licences with seasonal variations can be modelled.