The calculation of water depth at vena contraction in the open channel with arc-bed trapezoidal cross section is to solve the transcendental equation. Aiming at some problems of traditional algorithms （graphic algorithm and try algorithm） such as the calcula-tion process is tedious, and the accuracy of results is not high, and so on, the simple and more accurate approximation formula is ob- tained for calculating water depth at vena contraction in the open channel with arc-bed trapezoidal section by which the transcendental function derived from transforming the basic equation is optimized, fitted and replaced, and then successive approximation fitting and calculation is conducted within the scope of engineering applicable parameters taking the minimum standard residual difference as the objective function. The application of the simplified formula can improve efficiency obviously and precision further.
Journal of North China Institute of Water Conservancy and Hydroelectric Power
arc-bed trapezoidal cross section
water depth at vena contraction