I have modelled a section of river with a crump weir and then bridge about 10 metres downstream and then a culvert a further 80-100 metres.
At the bridge and the culvert, the model is showing critical peak flow levels, which increases water levels by at least 0.5m on the upside of each structure.
The bridge has one central pier with 2 openings, one arch and one square. I have modelled these as culverts. is this the correct approach?
why is this happening?