For new or retrofit applications in channels where no drop across the flume can be accommodated, the Trapezoidal, Cutthroat, Palmer-Bowlus, and RBC flumes are the first types of flumes to consider.  Of these, the Cutthroat flume should be considered for rectangular channels, the Trapezoidal and RBC flumes should be considered for trapezoidal shaped channels, and the Palmer-Bowlus for pipes and u-channels.

If a drop in elevation can be accommodated, or if the flume can be elevated above the floor of the channel, the Parshall flume can be considered.  

If the flume can be situated so that it is at an elevation sufficient to allow for free-spilling discharge under all flow conditions, the Montana and H flumes can be considered.