Comparing Routing Options 1 and 11

We are getting a larger peak outflow from Option 1 than Option 11 for this dam failure (i.e. 12,000,000 cfs vs. 8,885,000 cfs). The negative flood wave is not much larger than 1 foot and the Option 1 results match up with a previous 1980 study using HEC. Do you feel that the Option 11 results are still more accurate? I can't find the total reservoir volume calculation in the Option 11 Analysis Results for comparison with known values - please help with this.

Thanks,
Dan

Dear Dan :

Routing Option 1 will give you larger results over Option 11, since Option 1 does not account for any backwater effects at the dam's tailwater. Option 11 accounts for the tailwater submergence effect. However, a more conservative approach would be to consider only Option 1.

Also, Option 1 is the only option that provides a Reservoir Depletion Table. This is because with Option 1, it does the reservoir routing separately from the river routing--so it has the output data to construct the table. All of the other routing method options are fully dynamic, and therefore do not write out this table.

At one time I tried to rewrite DAMBRK so that it would generate the Reservoir Depletion Table for any option, but the source code for DAMBRK was just to complex to complete this in a reasonable period of time.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

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

Thanks for the quick feedback!