Ungaged Lateral Inflow

[Anonymous]

I’m attempting to model about 3 km of a small mountain stream for sediment transport purposes. I have a flow hydrograph for the upstream end and the downstream end, but no measured flows/stages within the reach. The downstream hydrograph consistently shows higher flows, because it accumulates lateral inflows along the reach. So far, I’ve only been able to use a normal depth downstream boundary condition, because the model can’t account for the extra flow showing up downstream. I was hoping to use the Ungaged Lateral Inflow tool to solve the problem, but it seems that I don’t have enough data to initialize it. The topography points to a few tributary creeks that probably account for most of the additional flow, but I have no known stage/flows at those points. …in other words, no Internal Boundary Conditions. Any suggestions?

[Toby]

You can try to scale your lateral inflows to your input hydrograph, based on drainage area. An HMS model might be better, but more time consuming.

Check out https://water.usgs.gov/osw/streamstats/ and see what data you might be able to find.

[Anonymous]

Yeah, I guess the solution really is HMS, but I’m trying to avoid it for now. I’ve estimated some lag times, lateral input locations, and fractional runoff areas, and that seems to be matching up pretty well. Thanks for the input.

[Author]

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