To all users but especially to Wayne:

First of all thanks to Ching Len Chen for his posting and reply. I take this opportunity to reopen the discussion of ranking potential upgrades to the SWMM engine.

It seems to me that current stormwater management strategies are, or ought to be, much more oriented towards infiltration BMPs. At least in this part of the world. Of course the major concern is the fate of pollutants in the ground.

SWMM RUNOFF does not attempt to route groundwater or interflows from one compartment to another. Better coding is clearly required. I have mentioned this requirement quite often both on this list and in personal notes to Wayne. My purpose here is to seek support from you all.

Put simply we need better groundwater compartment routing, and I know that this is a tough assignment, involving a redesign of the link between surface/ground hydrology, and also TRANSPORT. Ipso facto, it should be done first. After that, we could consider integrating planview graphics, and generalize input for physical drainage (RUNOFF, TRANSPORT, EXTRAN and STORAGE all currently require different forms of similar info.) because only then will we know what the fundamental code will be.

If you agree perhaps we could discuss minimum specs for routing groundwater - e.g. does urban groundwater often follow predictable paths? Is much urban groundwater in fact somewhat managed (flows to basement drains)? Or towards ponds placed on drainage systems? Could urban grounwater routines initially be along a preset direction IOW as a dendritic network (which allows very much simpler coding)? Can urban groundwater be modeled explicitly, as is done in most surface water models, rather than implicitly as is done in most groundwater models? What % of urban applications can be covered by dendritic groundwater networks?

If so perhaps SWMM5 could easily be made to be more useful but not require a major rewrite. Personally I would like to see in SWMM some sort of start towards comprehensive groundwater/surface water interaction, not more accurate than one subcatchment (iow not specifying local hillslopes).

Or is this a pipe-dream? Thanks for your time.
/bill

from Dr Chen:
The issue is not the continuity check, but the soundness of simulation of physics.
--snip--
There are a lot of other issues can be discussed in the groundwater module. We may discuss that latter if you are interested.
--snip--