I am having an issue with an unsteady model. For some reason after my first cross section the flows in the model go through the roof. For example. I am creating a hot start run with a 50cfs flow for the entire hydrograph. My max WS elevations go to the max and if I look at the flows in each RS the only one that makes sense is my most upstream RS (#13). The combine flow in RS #13 is 50cfs. The combined flow in RS #12 is 892cfs! Any ideas on why this is occurring when I should have a constant 50cfs?
What is the max error you are getting? Have you tried adjusting your timestep to be smaller? Have you tried interpolating cross-sections to see if your cross-sections are too far apart? 50cfs is a small amount of flow and could possibly cause problems, have you tried a higher flow? Have you checked the HTAB parameters? Are the initial conditions set up correctly?
Thank you for input Cameron. I did check the Htab and have them set to 100 points and a 0.5ft increment. I did try upping the flow to 100cfs, but that didn’t help. I thought the stream was running dry. Unfortunatley, or fortunately I don’t have any errors. For some reason my flow goes from 50cfs or 100cfs up to 350cfs in the second XS. I have tried various XS spacings down to 50ft. I am not sure what I can adjust on the initial conditions?… For the hot start file I have the initial flow set to 50 or 100cfs. Is there anything else I can adjust?
I believe I solved my issue. The model was running dry… well almost. The upstream cross sections did not have field topo data. I had to manual adjust the cross sections to have a more defined bed and bank. This resulted in a realistic model. It is strange that when the model was having issues there were zero WS errors.