Dams are solid barriers constructed across rivers to store flowing water for uses like hydropower, irrigation, water supply, flood control, and navigation. The key parts of a dam include the heel, toe, abutments, galleries, diversion tunnels, spillways, and sluice ways. There are several types of dams - gravity dams rely entirely on their weight and have foundations in competent rock; buttress dams are gravity dams reinforced with supports; arch dams are curved to transmit water pressure to abutments; and earth dams are constructed of clay, sand and gravel where foundations are weak. The Bhakra Dam in India is the highest concrete gravity dam in Asia.