Method B allows elevations and optionally material (Manning’s n) values to be assigned to points along a WLL. A more accurate representation of velocity and flood hazard from the 1D domain can be mapped. The velocity at a point on the WLL is estimated by carrying out a parallel channel analysis along the WLL using the flow in the channel the WLL is connected to. The analysis estimates the water surface slope at the WLL based on the conveyance of the profile along the WLL. Implicit in this analysis is that the cross-section selected for the channel produces an average water surface slope representative of that along the length of the channel. The water level at the WLL still remains the linearly interpolated water level from the upstream and downstream nodes.
Method B can have 2 and 3 vertex WLLs as discussed for Method A, as well as WLLs with no limit on the number of vertices. For WLLs with 2 and 3 vertices, the rules discussed above for Method A apply. For 4 or more vertices, one of the vertices (except for the two end vertices) must snap to a vertex on the channel line.
There is one attribute required for Method B (none are required for Method A) as described in Table 4 .27. The attribute, dMin, is the minimum distance in metres along which to generate elevation points for that line. If dMin is zero, only elevations at the mid and end points on the WLL are generated.
Table 4.27 1D WLL (1d_wll) Attributes
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