Problem

Can SewerGEMS be used to model backflow through a catch basin and into a gutter? In other words, can the flow from a catch basin vault back up and overflow into the gutter, pass downstream and approach the next inlet?

[Problem ID#: 89471]

Solution

This can be modeled in SewerGEMS and CivilStorm V8i SELECTseries 3 (or higher) using the Explicit (SWMM) solver. This method is internally referred to as the Two Node Solution.

This case is used in the following inlet types:

• HEC-22 Catalog Inlet in Sag using any routing method.
• A user defined, catalog depth-capture flow curve in sag using any routing method.
• HEC-22 Catalog Inlet On Grade using Uniform, Kinematic Routing Methods.
• A user defined, catalog depth-capture flow curve on grade using Uniform, Kinematic Routing Methods.
• Max Capacity, using Kinematic or Uniform flow Routing.
• Percent Capture, using Kinematic or Uniform flow Routing.
• Inflow Captured flow curve using Kinematic or Uniform flow routing.

If you look at the below screenshot, this shows a typical setup for an On Grade inlet. The catch basins are connected by a conduit and a gutter. When the SWMM solver is used, it is assumed to be like in the image at the bottom, where the solver will split the catch basin into two nodes, with subsurface and surface flow. Such a setup could allow for backflow in the catch basin to be picked up by the gutter and propagated downstream.

[Solution ID#: 500000100635]

See Also

Understanding Known Flows

Understanding Flow (Additional Subsurface) and Flow (Additional Carryover)