What is the purpose of artificial levees?

Artificial levees are structures built along the banks of rivers to help contain and manage floodwaters. Their primary purpose is to increase the channel's capacity for holding water, effectively allowing more water to flow within the river without overflowing its banks. By raising the height of the riverbanks, levees prevent flooding in adjacent areas, protect infrastructure, and can help manage water flow during heavy rainfall or snowmelt periods.

The other choices do not align with the primary function of levees. For instance, permanently diverting river flow to the ocean would not occur with levees, as they are designed to contain and control rather than redirect the flow entirely. Decreasing the total volume of water in a river is not a function of levees; rather, they work to manage the existing water levels. Furthermore, while levees may unintentionally create some habitats as they alter landscapes, their main design is not focused on creating fish habitats but on flood control and water management.