If you are using Kinematic Wave Routing in SWMM 5 you can switch to Dynamic Wave if you have any issues with a continuity error. There is on potential issue, however, as you need to have an outfall in your dynamic wave model. You can get around this issue by adding a dummy isolated outfall but it would be better to have an actual outfall.
Adding a Dummy Outfall in SWMM 5 |