Rockfill dams are structures built using large stones and gravel, which are compacted to create a barrier that holds back water. These dams are designed to be strong and stable, relying on the weight of the rock material to resist the pressure of the water behind them. They are often used in areas where other materials, like concrete, may not be as effective or economical. The construction of rockfill dams typically involves the use of heavy machinery to transport and place the rocks. These dams can be more flexible than traditional concrete dams, allowing them to adapt to changes in water levels and seismic activity. Rockfill dams are commonly found in regions with abundant natural resources, such as mountainous areas or river valleys.