Have you seen any dam closely. The structure of the dams are almost identical. It is a barrier that impounds water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability.
Below is a photo of Grand Paradise of northern Italy’s dam.
In the next picture you’ll notice something in the walls of the dam.
Lets take you little bit closer…