Which structure is specifically designed to protect areas from flooding?

Levees are structures specifically designed to protect areas from flooding by acting as embankments or barriers along rivers or waterfronts. Their primary purpose is to contain water within a designated channel, preventing it from spilling over into adjacent lands during periods of heavy rainfall or melting snow. Levees can be made from various materials, including earth, clay, or concrete, and they aim to safeguard communities, agricultural land, and infrastructure from floodwaters.

Reservoirs can help manage water flow and temporarily store excess water, but they do not directly prevent flooding in the same manner as levees do. Bridges are built to provide passage over obstacles, such as rivers, and are not designed for flood protection. Dikes can also serve a similar function to levees in certain contexts, especially in coastal areas to prevent sea inundation, but the term "levees" is more commonly associated with river flood protection in the context of this question. Therefore, levees are the most accurate answer in this case as they are specifically intended for flood protection purposes.