ABSTRACT
The performance characteristics and calibrations of various shapes and sizes of the critical-depth, long-throated flumes have been studied. In this study, four flume models were constructed, two of which were bottom contracted, one side contracted, and the fourth a parshall flume, having side and bottom contractions. The flumes were calibrated. The laboratory result verified a computer model, which in turn was used to generate calibration data and to identify the performance levels of various shapes and sizes of flumes. The study showed that the critical-depth long-throated flume with bottom sill only which has been termed 'Modified broad-crested Weir' is the most promising flume device for irrigation discharge measurement since it combines accuracy, ease of construction and high performance tolerances.