Simplified general formula for calculating water depth in parabolic-shaped channel with contracted section

Conventional methods used to calculate water depth in parabolic-shaped channel with contracted section have the drawbacks of heavy computational effort and low accuracy. Additionally,the exiting simplified formulas can only be used in specific parabolic-shaped sections and are not simple enough to calculate the water depth. In order to solve these problems, the basic formula of water depth was modified by introducing the comprehensive parameters and dimensionless relative water depth. The simplified general formula was proposed by fitting a polynomial of higher degree while meeting the precision demand of engineering design. Computational results and precision analysis show that the maximum relative error of the general formula is only 0. 755%,which meets the precision demand of engineering design. Thus,the simplified general formula proposed here can be used in real practical applications.