An open flow channel is used to study the flow of water with a free surface. It helps in analysing uniform and non-uniform flow, used in the study of velocity, depth, and discharge. It forms the base setup for many hydraulic experiments.

Hydraulic control structures are engineered structures built in open channels (rivers, canals, drains) to regulate, measure, divert, or control water flow. They are used to maintain desired discharge, water depth, velocity, and energy conditions in irrigation, flood control, and drainage systems.