Mississippi and delta

The long profile ends in stiller water and a huge load. Tides in the Gulf here are modest, so a delta can persist. Distributaries, levées, and a floodplain the size of a country are the lower-course kit. The 1927 flood and the Old River Control Structure are human attempts to keep the river from jumping to the Atchafalaya — a capture story at engineering scale.

Meander cut-offs, oxbows, and artificial straightening sit on the same helicoidal-flow logic as the rivers lab. Raise discharge and competence rises; the floodplain takes water when the levée is overtopped or fails. Hurricane Katrina’s flooding of New Orleans was a storm-surge and levée-failure story on this coast, not a simple fluvial hydrograph — keep the mechanisms honest.

Compare a Lake District beck: same processes, no delta, because the load and the coast disagree. Compare the Nile or the Ganges only if you keep the numbers sourced. This case is USGS and USACE territory.