The Aging Delta of a Country in the New World, the Mississippi
The Mississippi delta, encompassing an area of 25,000 km 2 , entirely belongs to the state of Louisiana, as much from a physical standpoint as a cultural and human one. The lower Mississippi plain, several kilometers wide, is bordered by a double row of modest cliffs, named bluffs, ranging from 15‐60 m in height, and providing a natural limit to the spread of flooding. Construction of the artificial levee began in 1717 in New Orleans, upstream and downstream of the city that was the center of initial organized protection. The notion of a delta is more complex in the lower Mississippi valley. From the Mississippi delta and the Arkansas delta, located upstream, to the Mississippi River delta, which is the delta itself, the Mississippi has a somewhat disrupted geography in terms of its toponymy. The Atchafalaya flow rate has benefitted from partial defluviation of the Mississippi, which took place in the 16th Century.