I am wondering about the best way to model a pond underdrain.  The set up I am thinking of would involve a perforated pipe buried in gravel at the bottom of the pond, connected to an outlet riser and culvert.  There are a few ways that I could see this modeled:

1)The “model everything approach” i.e. model the perforations as orifices which are routed to the pipe, which is then routed to the final outlet structure.  I am usually dealing with existing infrastructure, and the level of detail required to model this accurately is usually not available. Also I have learnt that it is generally better not to make the model any more complicated than absolutely necessary.

2)Alternately, I could assume that the perforations will not be a limiting factor and simply model the underdrain as a single small orifice in the outlet riser. This begs the question about what the size of my orifice should be - the diameter of the perforated pipe?  I have seen a couple models where a reduced orifice size was used, but I am unsure about how that size was reached.

3)The most common approach I have seen, however, is to completely ignore the underdrain when modeling ponds, which is not something I am exactly comfortable with.

Your assistance is much appreciated.