Where is the flow measured in a Parshall Flume?

The flow in a Parshall Flume is measured at the throat of the flume. This is the narrowest point in the flume where the water accelerates and its velocity increases. At this point, the hydrostatic pressure is related to the flow rate, which allows for accurate measurement of the flow. The design of the flume ensures that as water passes through, it maintains a linear relationship between the flow rate and the height of the water above the throat.

Measuring flow at the throat is essential because it provides a stable and measurable parameter that is not influenced by downstream conditions or varying flow rates. Understanding this principle helps operators and engineers ensure accurate assessments of wastewater flow for treatment purposes and regulatory compliance.