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Hi,
I need to simulate unsteady flow in the steep river. So there is supercritical flow on the upstream boundary condition. I know I have to set Q and H on the BC in case of supercritical flow. My question is, what value should be elevation (H) on upstream BC with supercritical flow? How it works if I put hydrograph on the BC?

Now if I run steady flow simulation (Q=200 m3/s) and then integrate flowrate along XY on the BC, flowrate is not 200 m3/s. It depend on H. My question is, what value should be elevation (H) on upstream BC with supercritical flow? How it works if I put hydrograph on the BC?

And I have another question. If I compare simulation with Manning friction coefficient (n) and Strickler coefficient, results are different if I use 1/n as Strickler coefficient. In case of Strickler coefficient is result more realistic, so should I use it?

I have attached my files.
files.fm/u/6k5n6g4u

Hello

you have to prescribe data that are available. If you have only discharge as upstream input, you have to prescribe it with a 455 option. this will need to modifiy the bathymetry locally at the upstream boundary in order to smooth it and thus generate in an artificail way a subcritical condition.
if you have both conditions H and Q, you can prescribe them both but with a condition 555.

kind regards

Riadh