1 - Yes it is possible.

2 - You can use the SWMM engine in the shell of already existing codes for optimization to do that for you, like DAKOTA:

https://dakota.sandia.gov/release-notes-headings/uncertainty-quantification-uq

Or PEST++

https://www.usgs.gov/software/pest-parameter-estimation-code-optimized-large-environmental-models-version-3

So basically you do not need to write anything you only have to set the API and interface.

3- You have to find the source code of SWMM in Fortran or a version which let you wrap it up in a shell to run it with your other driver (DAKOTA or PEST)

Hope it helps,

Kaveh

Follow.

That is a good question.