Gravity Dam

A gravity dam is a dam built from concrete or stone masonry that holds back water using its own weight and shape alone, with each section of the structure stable independently of the sections beside it, unlike an arch dam, whose sections rely on each other for support. Its triangular cross-section is engineered to manage the immense horizontal pressure of the retained water, and because gravity dams are so heavy, they generally require a foundation of stiff, high-bearing-strength rock, though they remain vulnerable to cracking from uneven foundation settlement and to uplift pressure from water seeping beneath them. The earliest known gravity dam, Sadd el-Kafara on the Nile, was built by the ancient Egyptians around 2950 to 2750 BC and stood roughly fourteen meters high; gravity dams have since become a standard structure for flood control, hydroelectric power generation, irrigation, and water supply worldwide.