Measurement of discharge in open channels: A case study of laboratory discharge calibration model

Abstract

In order to obtain an identical implementation in the field, flow testing is frequently conducted by creating physical models in the laboratory to describe the actual flow in the field with physical models in the laboratory; thus, a series of calibration tests are required. In this study, the equation obtained from the results of the threshold calibration has been conducted. The equation formed from the three calibrated thresholds includes the triangular threshold (weir#2), the discharge equation Q=0.0144 h^2.5726 (l/s) the r2 value 0.9918, and the rectangular threshold (weir#1) has the discharge equation Q = 0.378 h^1.9223 (l/s) the r2 value is 0.9507. The discharge coefficient obtained is Cd=2.0729 h^0.622 for the triangular threshold (weir#2) and Cd=4.5172 h^1.1414 at the rectangular threshold (weir#1). In the calibration process, the accuracy of the obtained results is highly dependent on the accuracy and precision at the time of measurement, and in addition to the completeness and suitability of the equipment and facilities required for the calibration, In small discharge, the measurement must be conducted because smaller calibrated discharge leads to higher error rate.