How is flow depth measured in a Palmer-Bowlus flume?

In a Palmer-Bowlus flume, flow depth is measured from the floor of the flume to the water surface. This measurement is crucial as it directly relates to the flow rate and hydraulic conditions within the flume. The depth of water above the floor indicates how much water is flowing at that moment, which is essential for accurately calculating the flow rate using the flume's specific rating curve.

Measuring from the floor ensures that the depth reflects the actual water column, which is critical for proper flow measurement and management in wastewater treatment and other applications relying on this type of flow measurement device. Other measurement approaches, such as from the top of the flume or from the sides, would not accurately represent the hydraulic conditions needed for effective flow analysis.