We have an ICM model which contains a length of canal running through the middle of the 2D zone. Some sections of surface water sewer discharge to the canal and hence its levels affect flooding within the model.
We don't have a model of the flows into the canal.

Initially the canal was represented within the 2D mesh and an Initial Condition 2D zone used to set the water level, but levels fall during the simulation as the initial volume drains out.

What is the best way of representing the levels within the canal in ICM?

None of the options I can think of seem ideal:
a) Fill the canal in the ground model; this might cause issues with the outfalls from the SW sewers which will then be below ground
b) Use a 2D level boundary, but I'm not sure how (we might need to apply different levels to different sections of the canal, which isn't currently at the edge of the 2D zone)
c) Model the SW outfalls to the canal as 1D outfalls and apply a level file