headgates

Headgates are hydraulic structures located at the upstream end of a canal, penstock, or turbine intake that regulate the flow of water into the conduit. They form part of dam headworks and hydroelectric plant intakes, providing control over head, discharge, and backflow. By adjusting the opening, a headgate determines how much water enters the conduit, helping to maintain reservoir levels, protect downstream reaches, and coordinate with spillway operations.

Construction typically includes a gate or set of gates mounted in a reinforced frame with guides and supports, and an upstream trash rack to trap debris. Gates are actuated by manual mechanisms, electric or hydraulic operators, and may be controlled locally or remotely, sometimes automatically in response to flood signals or turbine load. Stoplogs or removable panels can be used to close off the intake during maintenance. The structure also incorporates seals, drain systems, and safety features to prevent unintended water ingress or gate failure.

Common headgate gate types include vertical lift gates, radial gates, and drum gates, selected for reliability, tight closure, and space requirements. Design considerations include the maximum head and water pressure, sediment and debris loads, intake protection and flushing provisions, maintenance accessibility, and redundancy to ensure continued operation of power or irrigation systems. Proper operation relies on regular inspection and maintenance of moving parts, lubrication of hinges and seals, testing of actuators, and verification of backup power to ensure rapid closure in emergencies.