Modeling Infiltration with Waterworks (DOS)

[DLervik]

I'm looking for some help modeling a series of bioretention pools using the good ol' DOS version of Waterworks.

Scenario:
The system is three compost berms along the contours of a hill above a wetland. The runoff enters the first berm. If the flow exceeds both the volume of the pool and the infiltration rate (60 min/inch), then it overflows into the next pool. Whatever comes out of the last pool can proceed as surface flow into the wetland.

Method:
Each pool is modeled as a zero-width trapazoidal pond. The length matches the design, and the depth is adjusted to acheive the volume from the site model. The input table is set up so that the Output hydrograph of the upper pool becomes the input hydrograph for the subsequent pool.

Problem:
Waterworks(tm) appears to include the runoff that disipates by infiltration in the "outflow" hydrograph. Therefore, storm events that never reach the stage of the overflow weir (and thus never discharge to the next pool) still have an apparent outflow hydragraph.

Question:
How do I model this so that infiltration is handled properly?

Thanks in advance.

Dave

 

[bltseattle]

I would try using the SPLIT LPOOL option to separate out the discharge over the weir from the net discharge.