I'd Value Your Input on Case Study Using Hydraflow Hydrographs

[Anonymous]

Hi All,

I'm looking for someone to independently verify some results from Hydraflow Hydrographs. I'm baffled as to the behavior of this tool and would appreciate your thoughts to help explain it.

The situation: the pond has a wet pond elevation at 491. Thus, storage of incoming hydrograph should begin at this elevation. In my original work with this data, I noticed that the model lacked contour information for stages 1 and 3. I added data for these two stages, which did provide more detail, but did not affect storage for the pond. In fact, it shouldn't change any of the results since stages 1 and 3 are below the wet pond elevation. However, the results were dramatically different when compared to the original data set. Why is this? Why would additional information, which should not impact storage, change the results in any way?

The Hydrograph files are provided via the links below. The "design" condition is "13010 revised pond 2-15-12.gpw" and the same data set with contour data below 491 removed is "20140624 What If Scenario...".

https://www.dropbox.com/s/7e7tvrj7mwuzqo6/13010%20revised%20pond%202-15-12.gpw

https://www.dropbox.com/s/5yi6ilgsl0nts6p/20140624%20What%20If%20Scenario%20to%20Check%20Design%20Co...

I'd value your thoughts on explaining the behavior of this tool. Perhaps this is a bug or maybe there's a rational explanation that I'm overlooking.

Using Civil 3D 2011

On a broader topic, does anyone have suggestions on how to get technical support for this tool?

Thanks,

[jrauch]

In the "What If scenario" file that you provided, the wet pond elevation was set to 493. I reset it to 491 (Dry Pond) and it worked fine.

[Anonymous]

John,

Thanks for taking a look and great observation. It seems that removing the contour data below elevation 491 affects the starting elevation. Though, there's no notification that the value has changed as a result. In fact, that information doesn't even appear on older versions of printed reports.

You're right that 3 out of 4 of the results are duplicated, however the 100-year return period is off by nearly 20%. Both peak flow and maximum elevation are different when comparing the two data sets. If the only difference between the two data sets is contour data below the wet pond elevation, it's not clear to me why I wouldn't see reproduced results across the board. Theories?