Discharge ratings for control gates at Mississippi River Lock and Dam 22, Saverton, Missouri

The water level of the navigation pools on the Mississippi River are maintained by the operation of tainted and roller gates at the locks and dams. Discharge ratings for the gates on Lock and Dam 22, at Saverton, Missouri, were developed from current-meter discharge measurements made in the forebays of the gate structures. Methodology is given to accurately compute 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 and free-weir flow. Rating discharges are given for comparison to those used in the operation schedule, Plan A, which is in use for the operation of Lock and Dam 22.