All Conditions?

[sami]

what are the boundary & initial conditions for a river with 1 reach?
e.g. a flow hydrograph for upstream & a normal depth(in fact the slope), for downstream as the boundary conditions?
& the initial condition is just the initial flow for first station at the upstream?
Are these enough?

[Chris G.]

For a RAS project that only has one river/reach, you would have, at a minimum, one upstream boundary condition, and one downstream boudnary condition. The upstream is typically a flow hydrograph, but could be flow hydrograph, stage hydrograph, or stage/flow hydrograph. The downstream boundary condition could be stage hydrograph, flow hydrograph, stage/flow hydrograph, rating curve, or normal depth. Typically I see either stage hydrograph or normal depth as the downstream boundary. Sometimes a rating curve. And yes, the initial conditions is typically the first time-step flow (from your upstream boundary flow hydrograph).

That’s it.

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