The measurement of flows in flat/low gradient areas can be challenging.  

Fortunately both the Trapezoidal and Cutthroat flumes are available for these applications.  Both flumes have flat floors and do not require a change in elevation from the inlet of the flume to the outlet of the flume (as a Parshall would).  Additionally, both types of flumes have high submergence transitions (reflecting their resistance to the presence of downstream waters).

RBC flumes can also be used in flat/low gradient areas, but with the ramp section in the flume, there is always standing water upstream which may cause sediment to settle out during no / low flow conditions.

H Flumes (HS / H / HL) and Montana flumes should never be used in flat / low gradient applications as they require free-spilling discharges.