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Hi TUFLOW family, I have a question regarding modelling older arch culverts in TUFLOW where the bottom of the culvert contains curved edges (see attached image). For the culvert I'm currently trying to model, when I include the curved sections in the the required HW table, TUFLOW throws the following error: https://wiki.tuflow.com/index.php?title=TUFLOW_Message_1343. To get around this, I made the sides completely straight - and that worked fine, but I'm concerned that the flow through the culvert may now be overestimated. Modelling the culvert this way (as an irregular culverts in a 1d_nwk layer) obviously has constraints when H values don't always increase. Does anyone have a solution to a way around this problem? Given there are a lot of historical 'arch' culverts around Australia, this may be a limitation if the curved sections cannot be modelled.

Hi there, Im modelling an Arched bridge in a 1D network channel and trying to calculate the Loss Coefficients to form part of an LC table. Im using Figure 6 in the Hydraulics of Bridge Waterways from March 1978 Backwater coefficient to help me. I am using a 30 degree wingwall value. My Bridge is 4.42m wide at an elevation of 55.799mAOD and the cross section is 6.025m on the upstream face. Using this value gives me a M value of 0.73 and conversely a Kb value of 0.5. This loss seems a little high as this is the springing point of my arch. As I work out the LC table, nearing the top of the arch, I recalculate the coefficients. At an elevation of 57.449, the channel section is 12.796 and the arch is 3.552 wide, giving me a constriction of 9.244. This gives me an M value of 0.277 and a Kb value of 2.2 Finally, just below the soffit, the bridge width is 1.776 at the top. The channel width is 12.796 and hence the constriction is 11.02m. Which gives me an M value of 0.13 and a Kb value of 3 How do the Kb values listed above, fit in with an accepted loss value of 1.56 at the soffit. Is the 'M' opening ratio being calculated and applied correctly.