Updating Channel Geometry

A range of methods for updating the channel geometry are available:

(0)                     no change in channel geometry (fully decoupled)

(1)                     move all section points uniformly by the Δ z calculated for the particular section

(2)                     move only those points at a section below water level uniformly by the Δ z calculated for the particular section

(3)                     move those points below water level by a Δ z distributed according to shear stress (scaling Δ z at every data point)

Method (1) is faster as the existing channel section property arrays need only their elevation data changed, whereas methods (2) and (3) are slower as each step will probably necessitate a full recalculation of the section properties. However, it is important to note the possibility for method (1) to generate large errors, especially when significant proportions of the channel section are above water for most of the simulation period.

The channel geometry will be updated only after a user specified cumulative Δ z value has been exceeded. For example the user can specify that the geometry will be recalculated after a net depth of 10mm of erosion or deposition has been achieved. This criterion is applied at each node independently.