I'm running an unsteady simulation that has a junction (Johnson Creek and tributary Kelly Creek). Johnson Creek is very low gradient (average slope 0.2%). Kelly Creek is steeper with average gradient of 1.4%. The steady state simulation shows the lower end of Kelly Creek is backwatered by Johnson Creek (when flows on Johnson Creek exceed about 50 cfs). When I run the unsteady model, I get the following error in the boundary conditions file. It says the minimum streambed elevation (235.24) at the lowest cross-section on Kelly Ceek is above the computed water surface elevation (233.8).
ERROR! The initial downstream stage, 233.80, for reach 2 was below the minimum elevation of the cross-section, 235.24. Either the downstream boundary for this reach was not specified or the reach connections in the cross-section file are not correct.
STOP! Downstream boundary not defined
The unsteady simulation starts with a base flow of about 20 cfs on Johnson Creek and 5 cfs on Kelly Creek. These are flashy urban streams. My boundary conditions for Johnson creek are a hydrograph at the upstream end and a rating table at the downstream end. My boundary condition for Kelly Creek is a hydrograph at the upstream end of Kelly Creek.
My model is very similar to the example model called Multiple Reach Data Set (3ReachUnsteady.prg). I've compared the boundary conditions and initial conditions. My model is set up similar to the example. I'm stumped. Any suggestions would be appreciated. If anyone has time/interest in taking a look at my model please send me an email address.
Thanks,
Janet Corsale, PE
jcorsale@interfluve.com
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