<human>:  Can you explain the difference between the three main types of levees?
<bot>: The three main types of levees are earthfill levees, rockfill levees and concrete levees. Earthfill levees are created from soil and rock that is layered and compacted to form a series of embankments along the water’s edge. Rockfill levees are constructed with rock and soil, but the embankments are made with sediment and earth instead of being compacted. Concrete levees are made with walls of reinforced concrete and may be raised or built at the same line as the water’s edge. All three types of levees are designed to reduce the risk of flooding by containing water and preventing it from overflowing its banks.