A dam is a barrier that stops or restricts the flow of surface 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. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions.
The Edersee Dam in Hesse, Germany
The Roman dam at Cornalvo in Spain has been in use for almost two millennia.
Remains of the Band-e Kaisar dam, built by the Romans in the 3rd century AD
An engraving of the Rideau Canal locks at Bytown
Surface water is water located on top of land, forming terrestrial waterbodies, and may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean.
An inland lake, an example of surface water
The entire surface water flow of the Alapaha River near Jennings, Florida going into a sinkhole leading to the Floridan Aquifer groundwater.
A stream gauge used to measure surface water.
