Abstract Submission: Parshall flumes have been used for flow measurement for over 70 years. Flumes can range in size from 1 inch to 50 feet in width. A 30-ft wide Parshall flume was installed at the headworks of Fresno ID’s Fresno Canal in the 1960s and has been operational since. Flow rate measurements have been taken to verify the accuracy of the flume periodically throughout the past 50+ years. In 2021/2022, a series of flow verification measurements were taken that indicated higher flows rates than the flume was reporting, specifically at high flows. This caused the water authority to question the accuracy of the head-flow charts and equations and propose an adjustment to the head-flow curve. The flume was surveyed in late 2022. ITRC reviewed the historical and recent flow measurements as well as the recent survey and determined that the flume had maintained the design dimensions, there were inaccuracies in the recent measurements, and the flume appeared to be measuring flow rate accurately.
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