Hydraulic structures are human-made systems interacting with surface runoff in urban and rural environments including structures to assist stormwater drainage, flood mitigation, coastal protection, or enhancing and controlling flows in rivers and other water bodies.

A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water.

The structure may is built across a natural stream to divert, control, store, and manage the water flow: for example, a weir across a waterway and its upstream reservoir controlling both upstream and downstream water levels

Hydraulic structures can be designed pro-actively to control the water flow motion: for example, a series of drop structures along a mountain river course built to stabilize the river bed by dissipating the flow energy along the drops.

For more info plz check out the link below

https://uomustansiriyah.edu.iq/media/lectures/5/5_2020_02_15!11_50_55_PM.docx

Agreed Faraed Salman