I am working on a dam breach analysis for hazard classification on a small dam (8ft) with a steep downstream reach and narrow/shallow channel. I’ve used modified puls, and calculated what my time step and distance between x-sections should be. In the antecedent condition, the model is stable, and provides results consistent with observations. When I run the breach plan, the model blows up (stops calculating all together) at a flow well below the peak on the inflow hydrograph. I’ve reviewed postings here, and reviewed Gary Brunner’s “Common Model Stability Problems When Performing an Unsteady Flow Analysis”, all to no avail. One other interesting thing is that the inline structure rating curve increases in elevation with increasing flow to a point up to around 1100 cfs, then drops off by about a foot to around Q= 1300 cfs, and remains level up to around 1500 cfs. Not sure if this could be related, but it seems odd. Any assistance would be greatly appreciated. Oh, and I’m using version 4.1.0.
Thanks.
Bob