Discharge ratings for control gates at Mississippi River lock and dam 20, Canton, Missouri

The water levels of the navigation pools on the Mississippi River are maintained by the operation of tainter and roller gates at the locks and dams. Discharge ratings for the gates on Lock and Dam 20, at Canton, Missouri, were developed from current meter discharge measurements made in the forebays of the gate structures. Methodology is given to compute accurately the gate openings of the tainter gates. Discharge coefficients, in equations that express discharge as a function of tailwater head , forebay head, and height of gate opening, were determined for conditions of submerged orifice flow. A comparison of the discharges defined by the hydraulic model ratings and those computed by the equations developed in this study are given for selected gate openings. (Author 's abstract)