Because of the way that water surface profiles are calculated in the different solvers, profiles for the same system and flows in a series of conduits may look different using different solvers. For example, a system with four weirs in series may look like this:

In SewerCAD/StormCAD GVF solver:

In SewerGEMS./CivilStorm Implicit dynamic wave solver:

In SewerGEMS/CivilStorm Explicit SWMM dynamic wave solver:

The profile in the dynamic wave solvers near control structures can be made to look more accurate by placing the control structures in a shorter conduit. For example, if the conduit is 400 ft, break it into a 40 ft and 360 ft conduit and place the weir in the shorter conduit.

By using these shorter lengths, the profile near the control structure can be made to look more realistic.

For the Implicit solver:

For the Explicit SWMM solver:

The conduit with the control structure should not be made extremely short or it may affect the stability of the run. For example, a 1 ft conduit can cause problems.