Engineers must de-water the river where the dam is meant to be built. This is done by diverting the river through a tunnel that runs around the intended construction zone. Tunnels like this may be lined with concrete and are usually dug out using a combination of drilling and explosives.

How do they build dams?

A dam is built on a soil or rock foundation, depending on the type of dam. The foundation must be strong enough to carry the weight of the dam, and the water pressures acting on the dam. ... This is done by drilling holes down into the rock, and by pumping grout into them, which spreads outwards to fill the cracks.

What materials are used to build a dam?

Dam Basics

The materials used for construction of dams include earth, rock, tailings from mining or milling, concrete, masonry, steel, timber, miscellaneous materials (such as plastic or rubber) and any combination of these materials.