Concrete dams are large structures built to hold back water in rivers or lakes. They are made primarily of reinforced concrete, which provides strength and durability. These dams create reservoirs for water storage, help control flooding, and can generate hydroelectric power. The design of concrete dams often includes a curved shape, allowing them to efficiently withstand the pressure of the water. Common types of concrete dams include gravity dams, arch dams, and buttress dams. Each type serves specific purposes based on the landscape and water flow, ensuring effective management of water resources.