The flow, Q, over a section of the dike corresponding to an element face with the length (width), w, is based on a standard weir expression, reduced according to the Villemonte formula:
(6.32)
where Q is discharge through the structure, w is the local width (cell face width), C is discharge coefficient, Hus is upstream water level, Hds is downstream water level and Hw is the crest level taken with respect to the global datum (see Figure 6.29). The default value of the weir coefficient is 1.838.
Figure 6.29 Definition sketch for Dike Flow
The geometry of a dike is defined as shown below.
Figure 6.30 Definition sketch of spatial varying dike geometry
