Editing Dam (section)

==== Arch-gravity dams ====
[[File:Hoover Dam (aerial view) - 30 April 2009.jpg|thumb|The [[Hoover Dam]], shown in 2009 with the [[Mike O'Callaghan–Pat Tillman Memorial Bridge]] under construction, is an example of an arch-gravity dam.]]
{{main|Arch-gravity dam}}

A gravity dam can be combined with an arch dam into an [[arch-gravity dam]] for areas with massive amounts of water flow but less material available for a pure gravity dam. The inward compression of the dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitational force required by the dam is lessened, i.e., the dam does not need to be so massive. This enables thinner dams and saves resources.