The measurement of water in open channels on extremely flat grades is difficult because of the head loss that is necessary. A modified venture section, the contraction of which is provided by a top cover section mounted in a rectangular flume, is proposed to meet the requirements of a suitable measuring device for use in canals of flat gradients. The method of finite differences has been used for the mathematical solution to the idealized inviscid flow problem. This was followed by a laboratory investigation to ascertain the hydraulic characteristics of the proposed design. The experiments were conducted in a 3 feet by 3 feet by 200 feet concrete flume. The equation for discharge as obtained in this study is as follows: Coefficient of discharge CD has been calculated for throat opening of 5, 6, 7, 8 and 9 inches. The results have been presented in the form of curves and these curves have been compared with the work done by previous investigators.
Rasheed, Muhammad Aslam, "Hydraulic Characteristics of a Modified Venturi Section" (1968). Reports. Paper 143.