Rectangular - Notch

The Rectangular Notch is an open channel flow metering device that was developed to measure the flow of surface waters and irrigation flows. The Rectangular Notch is a fixed hydraulic structure. It is used to measure volumetric flow rate in industrial discharges, municipal sewer lines, and influent/effluent flows in wastewater treatment plants. The Rectangular Notch accelerates flow through a contraction of both the parallel sidewalls. Under free-flow conditions the depth of water at specified location upstream of the flume throat can be converted to a rate of flow.