[2] Buttress or hollow gravity dams were originally built to retain water for irrigation or mining in areas of scarce or expensive resources but cheap labour.
A buttress dam is a good choice in wide valleys where solid rock is rare.
[4] Buttress dams of slab concrete construction became popular in the United States in the early 20th Century with the patented process of Norwegian-American civil engineer Nils F.
The loads from the horizontal water head are transmitted underground through the wall and the columns.
Depending on the shape of the pillars and the slab or vault water wall, a distinction is made between:[10]