Earthfill dams are structures made primarily from compacted earth materials, such as soil and rock. They are designed to hold back water, creating reservoirs for various purposes, including irrigation, flood control, and hydroelectric power generation. The materials used in their construction are often locally sourced, making them cost-effective and environmentally friendly. These dams typically have a broad base and a sloping design, which helps distribute the weight of the water they hold. Earthfill dams can vary in size, from small structures to large installations, and they are often reinforced with additional materials to enhance their stability and durability.