The preset coefficients A1 and A2 are intended for an ultrasonic level sensor located in the center of the trough in the direction of flow at a distance B ‘from the beginning of the flume neck. The equation expresses the functional dependence between the instantaneous flow and the level at the specific point of the Parshall flume. The consumption equation of the Parshall flume has the form: H d / h maximum groundwater flooding ratio Consumption equations H d water depth behind the gutter (to the level of the bottom of the front part of the gutter) H water depth at a distance B ‘in front of the neck US2 Ultrasonic level sensor entering the ACH: Correction channel US1 Ultrasonic level sensor entering the ACH: Level channel Any sedimenting substances are deposited on the bottom of the riverbed before the measuring flume, and therefore this method of measurement is not usually sensitive to sedimentation, and at increased flows, undissolved substances are washed away behind the Parshall flume. The advantage of the Parshall measuring flume is the fact that the overflow depth (level height) is measured in a tapering profile, where the velocity increases and the jets are more stable. For larger flow rates, it is advisable to use combined Parshall flumes.

The Parshall flume is one of the flume with a long neck and is used mainly in localities with a balanced range of flows. The specific Parshall flume is used to measure the instantaneous flow on the basis of the Q / h curve (dependence between the instantaneous flow and the level at the measuring point).

Flume flow sensor