parking lot drainage using orifice

[SANDPI]

Hi,

I am trying to simulate a commercial site on SWMM. Some subcatchements have a restricted release rate and some (already developed), don't.

I tried to model it using storage and orifices where release rate is restricted. I link the subcatchment to the storage, then I link the storage to the orifice and finally the orifice to the node. Is that a proper way of doing it?

I was not sure about the storage and just added a tabular curve with basically 2000m2 at any height (rectangular box). What I want to do is to simulate some retention on the parking lot, roofs, etc (without having to bother about it within swmm).

Also, when I model the orifice, I found the equivalent circular diameter for the Qmax, should I enter this number as the orifice height only or as both, width and height?

Thanks a lot,

Sandra