I want to model a road in TUFLOW FV

[Guest Chris Nielsen]

I have a model mesh which has a road traversing a floodplain. What is the best way to include this in my model? Should I use a weir?

 

 

[Guest Chris Nielsen]

As a first approach, the road alignment could be directly inserted into the model geometry using a "cell elevation polyline" command. All you need is a csv file with the x,y,z coordinates of the road alignment (and, optionally, an ID column). This command will then set bed elevations for cells that are intersected by a polyline, interpolating cell z values from the z values specified at vertices along the polyline. This is a very handy tool and ensures that the road crest is preserved in the model geometry. The same approach can be applied to including a low flow / drain into TUFLOW FV.

 

The syntax for this approach in the fvc file is (assuming the input polyline file is roadalignment.csv, which has 4 columns with X,Y,Z,ID, and the road alignment of concern is ID=100):

 

cell elevation polyline == roadalignment.csv,100

 

Alternatively, you could represent the road as a weir. To do this, you could use the same input csv file of the road alignment, but apply a "nodestring polyline" command. This command will create a nodestring that best follows the x,y coordinates of the road alignment. Then, using the weir_dz structure type, the road alignment is simulated using a weir.

 

The syntax for this approach is as follows:

 

nodestring polyline == roadalignment.csv,100

structure == nodestring, 100

flux function == weir_dz

end structure

 

Which approach to choose? I guess this depends upon how important it is to accurately simulate flow over this road. See the following post for further discussion on this aspect.