Dams or dams are constructions built to withstand water rates into reservoirs, lakes, or recreation areas. Often dams are also used to drain water into a Hydro Power Plant. Most dams also have sections called water gates to dispose of unwanted water gradually or sustainably.

Dams (dam) and weirs are actually different structures. The weir is a low-head dam structure, which serves to raise the water level, usually in the river. The rising river water will melt through the top / overflow. Can be used as a measure of the speed of water flow in the channel / river and can also be a mover of traditional milling in European countries. In countries with large streams and heavy streams, a series of weirs can be operated to form a water transport system. In Indonesia, weirs can be used for irrigation if for example the river water level is lower than the face of the land to be irrigated.