Quantifying sediment from 2011 flood into Louisiana's wetlands

Space Daily via SPX: The spring 2011 flood on the Mississippi was among the largest floods ever, the river swelling over its banks and wreaking destruction in the surrounding areas. But a University of Pennsylvania-led study also shows that the floods reaped environmental benefits - transporting and laying down new sediment in portions of the Delta - that may help maintain the area's wetlands.

The study, led by Ph.D. student Nicole Khan of the Department of Earth and Environmental Science, is the first to quantify the amount of sediment transported to wetlands by a flood on the Mississippi. The results shed light on how floods impact wetlands, and how these effects might be harnessed to purposefully rebuild Louisiana's wetlands, which are sinking from compaction and growing smaller as sea level rises.

...A study by many of the same scientists, published in Nature Geoscience last year, found that the 2011 Mississippi River floods deposited more sediment in the Atchafalaya River Basin, where the waters moved slowly over a broad area, than in the Mississippi River Basin, where levees and control structures funneled the floodwaters into a jet stream that shot water and sediment out into the Gulf of Mexico.

The current study, published in Geology, focuses specifically on the questions of how much sediment was laid down in the river basins affected by the flood and where the sediments deposited the most.

"The marshes may be able to maintain their surface area or height above sea level if they receive significant sediment, either from floods or hurricanes or normal fluvial processes," Horton said. "Ours is the only empirical study to obtain an estimate of how much sediment is deposited by a large-scale flood on the Mississippi."...

A barge on the Mississippi in Louisiana, shot by Ken Lund, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license