Discharge Correction for Longitudinal Settlement of Parshall Flumes

ABSTRACT A3-in. Parshall flume was installed at slopes of 0, + 1.9, +5.8, +7.8, +10.2, -1.2, -5.5, -7.8, — 9.4, and —22.8%. The flume rating, or measured discharge, was compared to the actual discharge for each flume slope with free outfall conditions. The results indicated that the Parshall flume accuracy is slope dependent. The flume rating was in error 32% at slopes of ±10%. A method for aligning the measured discharge with the actual discharge is presented for variable slope conditions.