Hello guys. I have a question, I’m modeling a dam but I’m not sure how can I define the water surface in the dam. I don’t want to model the dam break, I only want to model how the water suface changes in it.
I’ve been reading and I found the storage areas tool, but I need to be sure.
Thanks for your help.
From the Unsteady Flow Data editor, go to Options, select Internal RS Initial Stages, add the river station just upstream of the inline structure and enter the water surface.
Does the dam have gates? You can keep the gates closed (or mostly closed) until the lake fills up to the water surface you want. If you take this approach, you can have RAS write out a “restart” file. You can then use this restart file without having to wait for the lake to fill up each time. The restart file is optional, but it can save some time.
Another possible approach: you might be able to create two, 2D areas. The upstream 2D area for the lake (and anything upstream) and the other 2D area for anything below the dam. The dam itself is then a SA/2D Area connection between the two different 2D areas. This way you can specify a starting water surface for the upstream 2D area that is the water surface upstream of the dam. However, I generally prefer to have the dam inside of a single 2D area as opposed to being between two different 2D areas.
But if I don’t have gates, can I do the first option? and if i do this, I will only have to create a single 2D flow area for all (upstream and downstream)?
In the second option I won’t have to create a storage area, right? I will only have to create two 2D flow areas.
So, in both first and second option, I won’t have to create a storage area.
So the only outflow from the dam is over some sort of overflow weir?
If that is the case, you should just be able to run the model long enough with a constant flow to fill up the dam.
For the second option, the simplest would probably be to split the current 2D area so that you have two separate 2D areas.
If you have an elevation-volume curve for the lake, I suppose you could model the upstream side as a 1D storage area and the downstream side as a 2D area. It might run a little quicker. It wouldn’t be as accurate.
The project I’m doing is about visualize how the flow from an hydrograph come into the water surface of the dam in HEC RAS 5.0 and compare it with the results obtained in HEC RAS 4.0 (1D)
The idea is to make a 2D model in HEC RAS 5.0. That’s why I think I don’t need to include the gates in the project.