Watersurface dam

[Neko]

Dear all

Thanks for this excellent forum, it’s very helpful.

I’ve got some problems with HQ100 calculations in a little stream with a dam. The water does not overflow the dam but is spreading at one side of the dam as if the dam wouldn’t be watertight.
When I just type the channel-data and the highest point of the dam, then HecRAS displays that there would be no overflow of the dam. If I type the whole Crosssection with the depression on both side of the dam, then HecRAS displays two wathersurfaces (one in the channel, one on the other side of the dam) although the dam seems not to be overflowed. The watersurface elevation has the same hight in the channel as on the other side of the dam. (–>See the PDF of Profile M8 with same water volume)

Has someone an explanation or a solution to solve the problem?

I would be very thankful for your help in this matter!
Best regards
Neko
1517_Beinwil.zip
Dam_with_depression_profile_M8.pdf
Just_channel_data_profile_M8.pdf

[Robert]

Hi

I do stabilization your model:
1. Water out of channel
You have to remember, that Hec-RAS is 1D model. Therefore you must define Levees or obstructions blok, when Water out of channel, while banks are above water surface in the channel.

2. Hydraulic Tables CS and Bridge (HTAB Curves)
When EGL (Energy Grade Line) is unstable (increase- decrease) you have to edit parameters of HTAB.
Chris wrote excellent articel for this problem (see url)
http://hecrasmodel.blogspot.sk/2011/03/more-on-htab-parameters.html
http://hecrasmodel.blogspot.sk/2009/02/crazy-energy-grade-line.html
http://hecrasmodel.blogspot.sk/search/label/HTab
… .

You wrote about dam in your contribution, but you haven´t dam in your model, only bridge?!

regards!
Robert

1517_Beinwil.rar

[Anonymous]

Thanks Robert for you very helpfull answer and your demonstration how to solve my problem on my data! My problem was that I didn’t knew about the importance of levees!

Thanks a lot for your help!

All the best

Neko

[Author]

Posts