Ponding behind culvert
Ponding behind culvert
(OP)
When using custom pond stage data to model a culvert crossing, is it necessary to enter an elevation higher than the top of the road to define overtopping? For example, if the elevation of the center of the road is 103.5, is it necessary to enter a value of say, 103.6, (accompanied by a very large surface area to simulate an infinite amount of storage now that the water level has over-topped the road)?





RE: Ponding behind culvert
In your case, you would probably model the roadway as an overflow weir. For accurate routing, you must define the storage to some point above the crest. This storage would NOT be infinite - it would be actual amount of storage controlled by the outlet devices. This would not include any storage downstream of the weir, since this is not part of the level pool and is not controlled by the weir.
When calcuating storage based on surface are, you would continue to enter the area at each contour line. As you excede the weir crest, use an imaginary vertical wall above the crest when calculating the area. Remember, your goal is to define the storage inside the pond that is subject to control by the outlet device(s).
RE: Ponding behind culvert
RE: Ponding behind culvert
RE: Ponding behind culvert
But if the water levels are different, you'll need two ponds: The first pond will have a primary culvert outlet, plus a secondary weir for the flow along the road. The second pond will have its own a culvert outlet going under the road.
In any case, I would not use a reach. For details please see www.hydrocad.net/reach.htm
RE: Ponding behind culvert
Thank you for your help once again!
RE: Ponding behind culvert
Device#1 = Culvert, Routing = Primary
Device#2 = Culvert, Routing = Secondary
For details on outlet configuration please see www.hydrocad.net/pond1.htm