WS or EG
WS or EG
(OP)
Designing a culvert : most software (e.g. HydroCulv, HY-8) gives the Upstream Head Elevation as final result.
Do you calculate the Upstream Water Surface Elevation (susbtracting v^2/2g) and use this water level to see if the conditions are ok (e.g. under the maximum allowable elevation) ?
Or rather use the Upstream Head Elevation ?
Do you calculate the Upstream Water Surface Elevation (susbtracting v^2/2g) and use this water level to see if the conditions are ok (e.g. under the maximum allowable elevation) ?
Or rather use the Upstream Head Elevation ?





RE: WS or EG
RE: WS or EG
Now, let's assume that the open channel HGL is lower than the culvert upstream HGL : do you use the WSE or the HGL to check if it's above or under the maximum allowable elevation?
RE: WS or EG
well, we both know that is impossible, so that would require a new analysis of the upstream channel HGL to estimate the true HGL in the channel.
remember, unless you have supercritical flow, water surface calculations must proceed upstream. that's why tailwater is so important and HY8 requires an estimate of your culverts tailwater conditions but not for headwater...
RE: WS or EG
The culvert might "choke" the flow to the point where the upstream water level is higher than the open-channel water surface level (calculted without a culvert there). Isn't?
Anyway, this wasn't my real question : In a culvert analysis report, do you calculate the WSE from the HGL (substracting the v^2/2g) or do you only use the HGL to compare with the maximum allowable water level?
RE: WS or EG
RE: WS or EG
Ok thanks!