The diversion of sediment-laden waters from the Mississippi River to the Bonnet Carre Spillway during the 2011 flood suggests that river diversions could help build new land along Louisiana’s retreating coastline, reports work published online in Nature Geoscience. The Bonnet Carre Spillway currently diverts floodwaters from the Mississippi River to a nearby lake, and was opened during the 2011 flood to prevent inundation of New Orleans.

Jeffrey Nittrouer and colleagues examined the aerial extent and thickness of sediments deposited in the Bonnet Carre spillway following the 2011 Mississippi River flood. They show that, despite the spillway only siphoning off the uppermost part of the flow, over 30% of the river’s sand load was diverted. They suggest that the location of the spillway relative to the river’s shape caused more sand - essential for building new land - to be carried off the river.

The findings suggest that engineered river diversions can aid in the development of new land.