Featured Research

from universities, journals, and other organizations

Centuries of sand still available at Mississippi Delta

Date:
April 21, 2014
Source:
Rice University
Summary:
The wetlands of the Mississippi River Delta are slowly sinking and rapidly eroding, but new research has found the river's supply of sand -- the material engineers most need to rebuild the delta -- will stay constant for centuries. "It's true that the total amount of sediment has diminished, but river sediment contains both fine-grained mud and course-grained sand, and our research found that upstream dam construction has not reduced the amount of sand in the lower Mississippi and won't for at least 300-600 years," said study's lead author.

These satellite images show a portion of the Mississippi River downstream of Memphis, Tenn., in August 2012 (top) and August 2011 (bottom). During the drought of 2012, record low-water levels revealed vast amounts of sand that are typically hidden below water. New research finds that the river’s supply of sand — the material engineers most need to rebuild the shrinking Mississippi Delta — will stay constant for centuries.

The wetlands of the Mississippi River Delta are slowly sinking and rapidly eroding, but new research from Rice University and the University of South Carolina has found the river's supply of sand -- the material engineers most need to rebuild the delta -- will stay constant for centuries.

The new study, which appears online this week in Nature Geoscience, is encouraging news for scientists and government officials who are working to shore up southeastern Louisiana's rapidly disappearing wetlands. The delta sinks each year as its soil settles and becomes more compact. While floodwaters from the untamed Mississippi River formerly provided a steady supply of sediment to counteract this subsidence, engineers have fought for nearly a century to contain the floods, which threaten the lives and livelihood of millions. Flood-control measures have eliminated about half of the annual supply of sediment that flows downriver, but the new study finds that sand -- they key ingredient for rebuilding marshlands -- is still abundant.

"It's true that the total amount of sediment has diminished, but river sediment contains both fine-grained mud and course-grained sand, and our research found that upstream dam construction has not reduced the amount of sand in the lower Mississippi and won't for at least 300-600 years," said study lead author Jeffrey Nittrouer, assistant professor of Earth science at Rice University.

Nittrouer and co-author Enrica Viparelli, assistant professor of civil and environmental engineering at the University of South Carolina, analyzed sediment loads in the lower Mississippi and found that while the total amount of sediment -- both sand and mud -- has diminished, the amount of sand trapped by upstream dams is offset by "mining" of new sand downstream.

"When clear water is released from the floodgates at upstream dams, it churns dormant sand that has long been deposited and carries it downriver," Nittrouer said. "This 'mining' of ancient sand makes up for the sand that is trapped by upstream dams, and our numerical models suggest that the sand load in the lower Mississippi River channel will not decline for at least 300 years. Looking even further into the future, we found that 600 years from now, the lower Mississippi River's sand sediment load will have declined by less than 20 percent from today's levels."

Nittrouer, whose research focuses on the sediment transport, hydrology, basin evolution and stratigraphy of lowland river systems, has studied the Mississippi River for the past decade. His previous work included a 2012 study of the land-building processes that took place during the historic flooding of 2011. In one of the largest floodwater diversions of the past century, the U.S. Army Corps of Engineers opened the Bonnet Carrι Spillway, a 7,000-foot-wide "safety valve" that diverts floodwater directly to Lake Ponchatrain.

Nittrouer and colleagues found that even though the 42-day diversion siphoned off less than 20 percent of the water flowing downriver, it diverted about 40 percent of the river's sand load into Bonnet Carrι. In analyzing how this occurred, Nittrouer and colleagues were able to show what factors the corps should consider in designing sediment diversion projects for wetlands replenishment.

"Our previous work showed how large volumes of sand could be deposited in specific locations, and our latest research shows that significant volumes of sand will be available for land-building for several centuries," Nittrouer said. "Each of these are important because studies at Wax Lake Delta and other sites have shown that sand -- even though it makes up less than 20 percent of the overall river sediment load -- is the key ingredient for land-building."


Story Source:

The above story is based on materials provided by Rice University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jeffrey A. Nittrouer, Enrica Viparelli. Sand as a stable and sustainable resource for nourishing the Mississippi River delta. Nature Geoscience, 2014; DOI: 10.1038/ngeo2142

Cite This Page:

Rice University. "Centuries of sand still available at Mississippi Delta." ScienceDaily. ScienceDaily, 21 April 2014. <www.sciencedaily.com/releases/2014/04/140421093927.htm>.
Rice University. (2014, April 21). Centuries of sand still available at Mississippi Delta. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2014/04/140421093927.htm
Rice University. "Centuries of sand still available at Mississippi Delta." ScienceDaily. www.sciencedaily.com/releases/2014/04/140421093927.htm (accessed August 23, 2014).

Share This




More Earth & Climate News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Airlines on Iceland Volcano Alert

Airlines on Iceland Volcano Alert

Reuters - Business Video Online (Aug. 22, 2014) — Iceland evacuates an area north of the country's Bardarbunga volcano, as the country's civil protection agency says it cannot rule out an eruption. Authorities have already warned airlines. As Joel Flynn reports, ash from the eruption of the Eyjafjallajokull volcano in 2010 shut down much of Europe's airspace for six days. Video provided by Reuters
Powered by NewsLook.com
Endangered Red Wolves Face Uncertain Future

Endangered Red Wolves Face Uncertain Future

AP (Aug. 22, 2014) — A federal judge temporarily banned coyote hunting to save endangered red wolves, but local hunters say that the wolf preservation program does more harm than good. Meanwhile federal officials are reviewing its wolf program in North Carolina. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Coal Gas Boom in China Holds Climate Risks

Coal Gas Boom in China Holds Climate Risks

AP (Aug. 22, 2014) — China's energy revolution could do more harm than good for the environment, despite the country's commitment to reducing pollution and curbing its carbon emissions. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Microbrewery Chooses Special Can for Its Beer

Microbrewery Chooses Special Can for Its Beer

AP (Aug. 22, 2014) — Aluminum giant, Novelis, has partnered with Red Hare Brewing Company to introduce the first certified high-content recycled beverage can. (Aug. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins