Mississippi River Delta may drown by 2100

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Washington, June 30 (ANI): A new research has predicted that the Mississippi River Delta in the US would drown by the year 2100.

"There's just not enough sediment to sustain the delta plain," study author Michael Blum of Louisiana State University in Baton Rouge, told National Geographic News.

Deltas are coastal landmasses created from a river's sediment deposits as the water flows out to sea. The Mississippi River's delta plain, for example, includes the lacy "toe" of southern Louisiana.

All deltas are degrading to some extent, as their sediment settles and sinks.

Today, sediments collected along the Mississippi cover about 23,360 square miles (60,500 square kilometers) ranging in thickness from less than 33 feet (10 meters) upstream near Memphis, Tennessee, to about 328 feet (100 meters) in the delta at the tip of southern Louisiana.

The drainage basin of the roughly 2,350-mile-long (3,782-kilometer-long) river, however, includes about 40,000 dams and levees built over the past century.

These structures control flooding and improve navigation, but they also trap sediment or funnel it completely through to the sea.

Previous studies suggested that dams and reservoirs built since 1950 have trapped as much as 70 percent of the river's natural amount of sediment.

With less material feeding it, the delta plain has been experiencing erosion.

But, even without the dams and levees, the amount of sediment flowing downriver would no longer be enough to sustain the delta because of rising seas, according to the researchers.

The researchers base their conclusions on estimated delta levels over the past 12,000 years, which show significant changes more than 7,000 years ago, when meltwater from the last ice age quickly filled the oceans.

The Mississippi Delta plain retreated inland at that point, and it was only after sea level rise had slowed considerably that the delta again grew seaward.

Current sea level rise, however, may be three times faster than it was the last time the delta was able to grow.

According to the researchers, with the added threat of rapid sea-level rise, sustaining the current extent of the delta plain would require 18 to 24 billion tons of sediment, which is way more than the entire Mississippi River currently carries.

The team therefore estimates that as much as 5,200 square miles (13,500 square kilometers) of delta land could disappear by 2100. (ANI)

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