New Scientist
Image: eutrophication&hypoxia
Maybe the Mississippi river delta isn’t doomed after all. Upstream dams on the rivers that run through the delta were thought to be starving it of the sediment it needs to stay above sea level – but now it seems there’s enough sand to feed the delta for centuries to come.
The Mississippi river delta, home to 2 million people and the largest tonnage shipping port in the US, is vulnerable to flooding – the city of New Orleans, which lies on the delta, was famously inundated as a result of hurricane Katrina in 2005.
The risk of such floods is made worse by the fact that the delta is losing land rapidly: 5000 square kilometres have been lost over the last 80 years. Much of the blame has been pinned on rising sea levels and a system of levees along the Mississippi river that flush river water – and the sediment it carries – out to sea rather than allowing it to settle onto the delta.
There are proposals to fight back by capturing the sediment before it reaches the sea, but it’s not clear how successful the schemes will be. The trouble is that the rivers flowing through the delta carry less sediment than they once did, because much of it is trapped by dams built upstream in the 1950s.
But it seems the dams might be off the hook, according to Jeffrey Nittrouer at Rice University in Houston, Texas, and Enrica Viparelli at the University of South Carolina in Columbia. Read more on newscientist.com…
