Variable tailwater at pond outlet

I am working with a residential development that proposes construction
of two SWM wetlands placed beside an existing natural wetland that
borders a creek. Previous MIDUSS modeling carried out in a community
services study makes use of stage/storage/discharge curves that are
identical for all events from the two year storm up to and including the
regional storm. Unfortunately, water surface modeling of the creek
results in a variable tailwater at each outlet with the 100-year storm
floodline being almost equal to the elevation of the berms around each
facility.

Can anybody advise as to the best approach for modeling this situation
with PCSWMM? I understand that EXTRAN is the only module which can
simulate tailwaters. Can this feature be used in conjunction with the
STORAGE module?

If possible I would like to use currently available inflow hydrographs
from MIDUSS and use PCSWMM to simulate the effect a of a variable
tailwater when routing through a storage unit.

Hydrographs for the creek depths are available.

With thank for any advise,
John Palmer (SWM practitioner in training)
johnp@BWORKS.ON.CA

John - You can simulate this problem soley in EXTRAN. Simply use your
pond elevation-area data to set up a storage node on the E1 and E2
cards. Inflows from whatever source can be coded on the K1-K3 cards;
the creek and its inflows and levels can also be included in the model;
however you will have to set up boundary conditions for the creek on the
I and J cards.

Hope this helps
Ron Kilmartin
ronkilmartin@attbi.com