Irrigation structures and hydraulic structures are used to regulate, measure, transport, divert, or stop the flow of water. They include dams, weirs, gates, culverts, and can be built in rivers, seas, or other bodies of water. Dams specifically are solid barriers built across river valleys to store flowing water for purposes like drinking water, navigation, flood control, irrigation, and hydropower. Dams are classified based on their design, construction material, size, and other factors. Key factors in selecting a dam site and type include foundation conditions, valley shape, availability of construction materials, and costs.