Tuflow and estry manual Version 3

Description
Type
Read MI WLL Command
dMin	The minimum distance interval along the WLL to generate elevation and material sampling points. These points also form the corners of the triangulation	Float

The default approach for setting the elevations at each point is to use the processed cross-section data (CS tables) for the cross-section allocated to the channel.

If Write Check Files in the .tcf file is specified, two GIS check layers are created. These are labelled 1d_WLLo and 1d_WLLp. 1d_WLLo reproduces the WLLs with attributes containing information on which channel and nodes the WLL was allocated to.

1d_WLLp contains all of the elevation points generated based on the dMin attribute. This layer can then be used to allocate elevations (first attribute) to each point from a DTM (in the same manner the 2D Zpts are assigned elevations).

A second attribute, RR, contains the relative resistance of the each point (which will have a value of 1 when first generated). The RR attribute can be replaced by the material value at each point by using a GIS to assign values from material polygons. The material value must exist in the .tmf file.

The attributes of a 1d_WLLp layer created by either Write Check Files or used in Read MI WLL Points are listed in Table 4 .28.

Note: If using Read MI WLL Points, this layer must be a copy of the 1d_WLLp layer produced by Write Check Files. Points from this layer can be deleted, but not added. At deleted points, the default of estimating an elevation from the channel’s processed data is used. If the 1d_WLL layer is modified or any of the dMin attribute values changed, the 1d_WLLp layer needs to be regenerated again.

For culvert channels (R and C channel type), only the end and mid vertices are used along the WLL, and the elevations are set to the culvert invert irrespective of the number of points along the WLL or the dMin value. This only applies to Method B.

Table 4.28 1D WLL Point (1d_wllp) Attributes