Cross Drains

[qpac]

I'm modeling a flood plain were the main channels are massive drainage ditches running along the road. At one point the ditch on the left stops and there is a box culvert that runs under the road to the a ditch on the other side of the road. Both ditches handle the 100 year flood, however the culvert does not. How should I model this? Does the ditch on the left, which basically dead ends, act as a detetion basin until it over tops the road and flows into the ditch on the right. The Box culvert runs perpindicular to the general direction of flow. What is the best way to model this scenerio?

 

[cvg]

try hec-ras

 

[francesca]

Personally I would not use HEC-RAS because it is more a detention basin scenario, particularly given that the box culvert is perpendicular to the flow direction. I cannot even begin to imagine the contraction/expansion reach calculations for that! Also I have tried HEC-RAS with a detention basin scenario and not had happy results compared to Hydraflow Hydrographs. I have more confidence in Hydraflow Hydrographs with a detention scenario than HEC-RAS because the calculation is stage-storage and not one-dimensional.

 

[cvg]

for a basin I would agree, however it doesn't sound to me like there is any substantial amount of storage in this ditch.