This is an example SWMM 5 model that can be imported into InfoSWMM or H2OMap SWMM using the Exchange/Import Command. The low flow falls over the berm of the leaping weir into a rectangular open channel but the the "falls" is governed by an OULET Depth/Discharge Type in SWMM 5. The flow increases in the OUTLET until a depth of 1 feet is reached where the weir starts to operate. The OUTLET increases in flow from zero to 1 feet but still flows at a reduced rate when the weir starts to operate. The weir stops flowing when the depth goes below 1 foot on the berm.
SWMM 5 Input File Link
|Leaping Weir With Low Flow Depth/Discharge OUTLET