AGU Fall Meeting: Accumulating sediment in Mississippi River threatens course change

December 12, 2017

The following release and accompanying images can be found at:

AGU Fall Meeting: Accumulating sediment in Mississippi River threatens course change, water supply

Ernest N. Morial Convention Center
New Orleans, Louisiana
11-15 December 2017

AGU Contacts:

Nanci Bompey
+1 (914) 552-5759

Lauren Lipuma
+1 (504) 427-6069

AGU Fall Meeting Press Room:

Morial Convention Center, Room 350-351
+1 (504) 670-5513

Included in this announcement: Please visit the 2017 Fall Meeting Media Center to view previous media advisories and press releases that include important information about press registration, badge pickup, press conferences, quiet rooms, searching the scientific program, and AGU On-Demand.

1. Research from the AGU Fall Meeting: Accumulating sediment in Mississippi River threatens course change, water supply

NEW ORLEANS -- Accumulating sediment within the lower Mississippi River could, when coupled with a major flood, cause the river to abandon its current course, potentially ruining the drinking water source for roughly 1.5 million people, according to new research presented here today.

The Mississippi River is an alluvial river, meaning its course is shaped by sediment and floods, and its floor is composed of loose, moving sands and soils. Because of these qualities, the river naturally changes course every 1,000 to 1,500 years. The Old River Control Structure, a 54-year-old floodgate system, manages the flow of the Mississippi into the Atchafalaya River, which runs parallel to and west of the Mississippi. This system prevents the Mississippi from flooding and changing its course.

In the new research, scientists took measurements of sediment accumulating downstream of the Old River Control Structure to the Gulf of Mexico, a total of more than 300 miles (more than 480 kilometers). The floodgate system regulates the flow of water, but it does little to address sediment moving downstream in the Mississippi, where this sediment accumulates when the river's flow naturally slows, according to the researchers.

The new research finds sediment has caused the river floor downstream of the floodgate to elevate and the sandbars to grow in volume by more than 200 percent. At least 36 million metric tons (over 39 million short tons) of coarse sand has been added to the river and narrowed the river channel by 800 meters (half a mile), according to hydrologist Yi-Jun Xu from Louisiana State University in Baton Rouge, who will present the new findings today at the 2017 American Geophysical Union Fall Meeting. Xu's previous research found these sandbars could swell even larger in the near future, as sand has also accumulated upstream from the control structure and could wash downstream under the right conditions.

These changes diminish the river's capacity to carry water on its current course. When sections of the river's floor rise to a sufficient point, a sudden increase in flow -- perhaps from a flood -- could drive the Mississippi River to overwhelm the control structure and adopt a new path, potentially causing the Mississippi to be captured by the Atchafalaya, according to the new research.

Xu believes enough sediment has already accumulated in the area to pose a risk. Another recent study also suggests that by the 2090s, changes in temperature and precipitation could increase the Mississippi River's flow by nearly 60 percent, increasing the likelihood of frequent and large floods. Rapid urbanization of the area, too, boosts chances of flooding, as paved surfaces deprive the land of its ability to store and slowly release water.

"When a mega flood comes, it will overpower the Old River Control Structure, if the river floor elevation continues," Xu said.

Such an event would cause saltwater from the Gulf of Mexico to intrude upstream, Xu said, compromising freshwater for the New Orleans, Metairie, Kenner, and Houma-Bayou Cane-Thibodaux metropolitan areas, which collectively include nearly 1.5 million people. The Mississippi River is serviced by water treatment facilities, though none are designed to process saltwater into freshwater.

"If that happened, it would directly affect the lives of nearly two million Americans as well as the multi-trillion-dollar petrol chemical assets along the lower Mississippi River," Xu said.

Notes for Journalists

Lead researcher Yi-Jun Xu will give a poster presentation about this research on Tuesday, 12 December at the 2017 AGU Fall Meeting.

Poster title:

What would happen if the Mississippi River changed its course to the Atchafalaya?


EP21C: Progress in Research on the World's Major River Deltas II Posters

Date: Tuesday, 12 December 2017
Time: 8:00 a.m. - 12:20 p.m. CST
Location: Morial Convention Center, Poster Hall, Halls D-F
Abstract number: EP21C-1855

Contact information for the researcher:

Yi-Jun Xu, Louisiana State University, Baton Rouge, Louisiana, U.S.A.:, +1 (225) 578-4168.

2. Today's press events

8:00 a.m. - Climate solutions: Policy, planning, science and engineering in uncertain political and economic times (Media Availability)
9:00 a.m. - Arctic Report Card 2017
10:30 a.m. - The IODP-ICDP Chicxulub impact crater drilling expedition (Media Availability)
11:30 a.m. - New Horizons explores the Kuiper Belt (Workshop)
1:45 p.m. - Why we are still in (Media Availability)
2:30 p.m. - New NASA eyes on ice (Workshop)
4:00 p.m. - The bright stuff: New Dawn findings at Ceres

All Fall Meeting press events take place in the Press Conference Room, Room 346-347. They will also be streamed live on the AGU press events webpage and archived on AGU's YouTube channel. Slides and other materials will be available in the Virtual Press Room on the Fall Meeting Media Center.

3. Noteworthy sessions happening today

Special Keynote Panel

A Special Keynote Panel titled "Why We Are Still In" will take place from 12:30 - 1:30 p.m. in the New Orleans Theater, located on the second floor of the Morial Convention Center above Hall I-1. AGU is facilitating this special plenary around the movement, a response to a U.S. governmental decision to depart from the Paris Climate Accord. Panelists include the Honorable James Brainard, Mayor of Carmel, Indiana; and Sra. Tanya Müller García, Secretary of the Environment, Mexico City. Registered journalists who are interested in attending this talk should meet an AGU staff member at the entrance to the lecture hall 30 minutes prior to the start of the talk. Journalists can also stream the lecture live on AGU On-Demand. A media availability will be held immediately following the lecture in the Press Conference Room, Room 346-347.

Town Hall Session: Updated AGU Ethics Policy

This year, AGU's Board of Directors adopted an updated Ethics Policy. This policy takes a much stronger stance against harassment by including it in the definition of research misconduct and expanding its application to AGU members, staff, volunteers, and non-members participating in AGU-sponsored programs and activities, including AGU Honors and Awards, and governance. The purpose of these updates is to address persistent ongoing issues of harassment, discrimination, and bullying within the sciences. AGU will be hosting a Town Hall session on the updated ethics policy from 6:15 - 7:15 p.m. in Room 203-205.

4. Potentially newsworthy presentations happening today

Late-breaking sessions

* Climate Solutions: Policy, Planning, Science and Engineering in Uncertain Political and Economic Times
Oral session GC23H, Tuesday, 12 December, 1:40 - 3:40 p.m., Room 252-254

* Late-Breaking Research Related to the 2017 Hurricane Season in the Americas
Poster session NH23E, Tuesday, 12 December, 1:40 - 6:00 p.m., Poster Hall D-F


* Cassini's Grand Finale: Discoveries and Science Highlights
Session U22A, 10:20 a.m. - 12:20 p.m., Room E2

* Induced Seismicity in the United States and Canada
Session S22B, 10:20 a.m. - 12:20 p.m., Room 222
Session S23C, 1:40 - 6:00 p.m., Poster Hall D-F

* Climate Science Special Report: An Assessment of the Science Focusing on the United States
Session U23A, 1:40 - 3:40 p.m., Room E2


* The Peculiar Negative Greenhouse Effect Over Antarctica
Session C21D, 8:00 a.m. - 12:20 p.m, Poster Hall D-F

* Determining Correlation between Shark Location and Atmospheric Wind and Thermal Parameters
Session OS21A, 8:00 a.m. - 12:20 p.m, Poster Hall D-F

* Lifetime Stable isotopes profiles in whale earplug: assessment of foraging and migrations in the Northern Hemisphere
Session OS21A, 8:00 a.m. - 12:20 p.m, Poster Hall D-F

* Using Digital Cameras to Detect Warning Signs of Volcanic Eruptions
Session V23E, 1:40 - 6:00 p.m., Poster Hall D-F

* Interaction of Geohazards and Settlements through the Past Millennium, Banda Aceh, Indonesia
Session NH23A, 1:40 - 6:00 p.m., Poster Hall D-F

5. Press networking events happening today

Journalism Awards Reception (5 p.m.)

Join your Press Room colleagues to honor and celebrate AGU's most recent journalism award winners during an informal reception on Tuesday evening. We will recognize the outstanding reporting and writing of 2017 Walter Sullivan Award for Excellence in Science Journalism-Features winner Tony Bartelme, 2017 David Perlman Award for Excellence in Science Journalism-News winner Courtney Humphries and 2017 Robert C. Cowen Award for Sustained Achievement in Science Journalism winner Rich Monastersky. The reception will take place in the Press Room, Ernest N. Morial Convention Center Room 350-351, from 5:00 - 6:30 p.m. Appetizers and drinks will be served.

Open Mic Night (7:30 p.m.)

Join your colleagues and host Richard Alley for an evening of rhyming, singing, and storytelling about Earth and space science at AGU's annual Open Mic Night at B.B. King's Blues Club, 1104 Decatur St, New Orleans, LA 70116, from 7:30 - 11:00 p.m. Appetizers will be served.

6. Online media resources

For journalists: During the Fall Meeting, journalists can find many resources online in the Virtual Press Room in the Fall Meeting Media Center. These resources include press releases, press conference materials and other information. Videos of press conferences will be added to the Virtual Press Room during the meeting for easy online access.

The AGU press office also offers two online tools to connect reporters with scientific experts at the 2017 Fall Meeting. The Find an Expert tool allows reporters to view a list of scientific experts who are available for interviews at the meeting. The Request an Expert tool allows reporters to send requests for experts directly to PIOs. These tools are now available online in the Fall Meeting Media Center.

For public information officers: PIOs are now able to share press releases and other materials in the Virtual Press Room by directly uploading them via the Press Item Uploader. PIOs can upload press releases, tip sheets and press conference materials to the Virtual Press Room at any time before or during the meeting, including uploading items in advance and scheduling them to post during the meeting.

The AGU press office also offers two online tools to connect reporters with scientific experts at the 2017 Fall Meeting. The Find an Expert tool allows public information officers to list scientific experts who are available to be interviewed by reporters at the meeting. The Request an Expert tool allows reporters to send requests for experts directly to PIOs. PIOs who wish to receive expert request emails from reporters should fill out the Receive Expert Requests form. More information about these tools can be found in the Fall Meeting Media Center.
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 60,000 members in 139 countries. Join the conversation on Facebook, Twitter, YouTube, and our other social media channels.

American Geophysical Union

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