Reservoir :- It is a store house to store the water.These may be created in river valleys by the construction of dam.Ex:Osman sagar reservoir on Musi river in Hyd.
• Dams are artificial barriers across a flowing river or any other natural water body that are meant to obstruct, direct, or slow down the flow of water, thus creating a reservoir or a lake.
Ex: Nagarjuna sagar Dam
• A barrage is an artificial obstruction at the mouth of a river that is used to increase its depth to assist in navigation or for irrigation purposes.
Ex: Doweleshwaram Barrage