6 Facts About / Examples of Submerged Flumes

Submergence in a flume occurs when downstream conditons combine to reduce free-flow out of the flume to the point where the free-flow discharge equations are no longer suitably accurate.

submerged painted steel irrigation Cutthroat Flume

While submergence corrections can be made for some flumes (Parshall, USGS Portable Parshall, Cutthroat, H flume, Montana), there is added complexity (measuring at the level at two locations) and cost.

submerged galvanized steel Parshall flume measuring irrigation flows

Some flumes can not be corrected for submergence (Trapezoidal, Palmer Bowlus, RBC). Typically this is because the submergence transitons (S_t) for these flumes is quite high - 80-90% - and attempts to correct the flow are to diffcult / costly / time consuming for the minimal returns.

submerged water rights Cutthroat flume

Remember that submergence can occur at any flow rate. Submergence is determined by the downstream conditons alone.

Cutthroat Flume experiencing submerged flows at normal flow rates

Any flume can experience submergence - although some types are more resistant (Parshall, Palmer Bowlus, Cutthroat, Trapezoidal, RBC) to its effects than others (Montana, H flume).

submerged Palmer Bowlus Flume

Although there can be advantages to designing an application to experience submergence from the outset, in general, Openchannelflow recommends that flumes be installed for free-flow conditions under all flow rates.

submerging Cutthroat Flume