Hi,
I am working on a SewerGEMS model and am having trouble understanding how the Hydraulic Grade Line within catchments is calculated. I will include screenshots of the model below. When I run the model and pass a storm event through the storm pipe network, there seems to be less surcharging in the manhole than I would expect. The furthest downstream pipe has a full flow capacity of 67.59cfs and the max flow in the pipe is 106.51cfs. When I do just a quick "sanity check" on this pipe flow I treat it as a quick culvert in Culvertmaster and look at the head. When I run the pipe as a culvert at 106.51cfs the head built up on the pipe is roughly 2 feet. However, when you look at the SewerGEMS profile for this pipe run, the surcharge into the structure is not nearly 2 feet. Maybe my way of performing a sanity check is incorrect, but this is a pretty large discrepancy. Is there something going on in the implicit solver that I do not understand? Any help on this problem will be greatly appreciated! Thanks!