The term Headworks is used in civil engineering for any structure at the head or diversion point of a waterway. Generally, it is smaller than a barrage and is used to divert water from a river into a canal or from a large canal into a smaller canal.
In the case of hydroelectric power plants, the headworks comprise of the diversion structures at the head of an intake. The headworks generally include booms and racks for diverting floating debris, sluices for by-passing debris, and sediments and valves for controlling the flow of water to the turbine.
Construction Engineers are always concerned to make Water flow into and through headworks as smoothly as possible in order to avoid head loss and cavitation. In practical designs, it is vital to avoid sharp corners and abrupt contractions or enlargements.
Also see: Hydroelectric Power Plant
See the below video for the Construction works of Headworks