Which HEC program is best for this application

[ScubaSteve1218]

There are several HEC programs available for modeling, but I'm not sure which is right for my particular problem.

First a little background:
There is a small lake here in South Jersey with a damaged dam/weir that needs to replace. This weir is the only outflow structure for a small lake.

I dont think I can use HEC-RAS because the upstream section isn't really a river. It seems to me that trying to draw the upstream cross section wouldnt make sense, because its not really flowing, its more of a storage basin. Any ideas which program could help me out?

 

[francesca]

Free software that does stage storage includes WinTR-55, HEC-HMS and EPA-SWMM. For a simple/small dam and weir with easily determined stage-storage relationship I'd probably go for WinTR-55.

 

[gbam]

FHWA's Visual Urban has a storage routing component that is relatively straight forward. I use VU for small onsite basins. For more regional sized basins I have always defaulted to HEC-1. HEC-1 can import a hydrograph and then route through a basin. I believe the HEC-HMS can be used for routing. I do not like the output from HMS so I stay with HEC-1.

 

[francesca]

WMS is a nice GIS wrapper for HEC tools, but it's very expensive. It does HEC-1. Is there a free graphical interface for HEC-1 yet?

 

[gbam]

Dobson put one out a while back but it too has cost. I am old school so I just code it.

 

[beej67]

WinTR-55 or VU are your best bets. I suspect the guts of VU are basically the same as WinTR-55, honestly.

There's a forum here on Eng-Tips that supports HydroCAD, which would be another fairly straight forward option. It's got a free 5 node trial version which should do fine for your application, but I think the free version still prints "EVALUATION COPY" on all your printouts / etc.



Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[ScubaSteve1218]

Thanks for the very quick and helpful responses. I had just installed WinTR-55 and started fooling around with it when I was informed by the superiors that I AM using HEC-RAS.

So I have another question for this, but as usual I need to provide a little more background:

As previously mentioned, the start of the stream will actually be a large pond that flows out through a wier into a stream. The problem im running into is that the weir we want/need to put in is a U shape, meaning part of it is perpendicular to the flow and some of it is parallel.

I know HEC-RAS can model the cross section (i.e. perpendicular length of wier), but what about the parallel faces of the wier?

If I can model this, what sort of data am I looknig for as my input?

A few cross sections (station and elevations) of the river and lake
peak flow data
length/size of the wier


Thanks again to everyone so far, Happy Holidays to All

 

[Drew08]

It seems we're missing something here. What is the point of this exercise? spillway design, base flood routing, other? And, where is your point of interest? Upper reservoir, at the dam, downstream of the dam?

If you want to do watershed and pond routing (i.e., hydrology) of a given rainfall event, HEC-RAS won't get you there, you need a hydrologic model like HEC-HMS, TR-55, etc (there are a million all equally capable and exceptable).

HEC-RAS is a hydraulic model that will solve a stage-discharge rating, or reservoir head at a given flow rate (i.e., hydraulics).

If all you’re interested in is the stage-discharge rating of the weir, and your point of interest is at or near the weir, or the reseroir can be assumed level, then I'd suggest skip the computational programs altogether and get out your hand calculator:

Flow Rate = Discharge Coefficient x Weir Length (total length of "U") x Reservoir Head^1.5

 

[francesca]

Well, you can do HEC-RAS for your routing, but WinTR-55 for your unsteady flow (i.e. stage-storage). If you use HEC-RAS under steady flow you're just assuming that there is no storage. (I.e. it's full to the top of the weir at the start of peak flow.) Depending on the depth of flow over the top of the weir, I would be less inclined to use the perpendicular length of the U and more inclined to use the total flow length. Or you could use the levee tool...

Isn't there a chapter in the Hydraulic Reference Manual about doing dam breach analyses?

 

[ScubaSteve1218]

Thanks all for your help. With the help of a few senior engineers who have more experience working in MS-DOS I was able to get HEC-1 running and finish the design.

 

[cvg]

well blyme, HEC1 is what I would have recommended from the beginning along with Excel... And what MSDOS experience is really needed?