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2D PO Lines

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I have a model with a 1D pipe network and 2D surface. I have placed 2D PO Lines across the roads to determine how much water is spilling from the underground drainage system. These PO lines do NOT cross any 1D network.

I have found that is some locations the PO hydrographs have a peak flow that is obviously incorrect (say about 20m3/s) even though it looks stable. To try to work out why the value was so high I placed more PO lines directly upstream and downstream of the subject PO line. I found that these hydrographs had a reasonable peak flow of about 1-2m3/s, which is what I was expecting.

The only difference that I can see is the PO Line causing high peak flows was much longer than the other PO lines. It may be picking up sheet flow on the side of the road however I didn't think that this would cause any problems.

Could anyone suggest why this might be occuring.


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One possible reason a Q PO line has more flow than it supposedly should is if there are other Q PO lines with the same Label attribute entry. TUFLOW accumulates the flow for all lines with the same Label attribute. This is a bit of a hangover from the days prior to GIS when the flow across a non-straight segment was required, so was entered as several segments with the same Label, but can still be useful today to accumulate flow from several lines.

Also check that the line is not duplicated in the 2d_po layer (ie. two or more instances of the same line are on top of each other - this can be easily done by accidentally copying and pasting the line on to itself).

If these are not the reasons, please email the .mif/mid files and the .tlf files to support@tuflow.com.



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