max flow

[emilias]

I have re-run the model (a single reservoir and a single reach - using option one) and I get a depletion table (the program seems to be calculating the outflow hydrograph from the dam), however the results the program produces for the downstream routing do not add up. From the final hydrograph (and the max flood), I can tell that only the initial flow is used and is not recognizing any of the breach outflow. Is there a trigger that I can use to have the program use all of the reservoir outflow and not just the initial value that is used throughout the time of analysis?

[Chris Maeder]

Note that Problem Specification Option 1 does a sequential routing of the flood and dam failure. That means that it first analyzes only the dam structure and generates output in terms of a Reservoir Depletion Table. Then, using these values, it then routes the flow downstream.

Since this is a sequential analysis, this method does not consider tail water submergence effects at the dam structure. This can greatly affect your analysis results.

I would recommend reviewing the Reservoir Depletion Table to see if there is any flow coming from the dam failure (variable QBRECH). Also, you can see how large the breach gets from this same table. This will tell you specifically how your dam failure is progressing.

You can also try switching to Problem Specification Option 13 to see if you get better results.

Sincerely,

Chris E. Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com