Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gulf bay double whammy: Rising seas, dammed rivers

26.10.2006
Oceanographers find dramatic 'flooding events' are norm, not exception

New research finds that every U.S Gulf Coast bay in Texas and Louisiana is vulnerable to significant flooding and expansion within the coming century due to a combination of rising seas and reduced silt flowing from dammed up rivers.

"Looking back over the past 10,000 years, we find the evolution of each of these bays is punctuated by rapid flooding events that result in landward shifts in bay environments of tens of kilometers and increases in bay area up to 30 percent within a century or two," said John Anderson, the W. Maurice Ewing Chair in Oceanography and professor of earth science at Rice University in Houston. "These flooding events can be triggered by either a rapid increase in sea level or a rapid decrease in the amount of silt flowing into the bay, and there's ample evidence to suggest that both of those will occur in each of these bays during the coming century."

Anderson will present his findings today at the Geological Society of America's 118th annual meeting at the Pennsylvania Convention Center in Philadelphia.

Anderson's results are based on his research group's analysis of dozens of sediment core samples drilled during the past decade from Galveston, Corpus Christi and Matagorda bays, all in Texas; Calcasieu Lake in Louisiana; and Sabine Lake, which straddles the Texas-Louisiana border.

"Over the past 10,000 years, there are an average of a half-dozen of these flooding events in each bay," Anderson said. "They don't correlate with any global increase in sea level, and they happen at different times in different bays, so we're confident that the driving factor in these events is a decrease in the amount of river-borne sediment flowing into the bay."

In the past century, multiple dams were constructed on each of the rivers flowing into each of these bays. Anderson said there is ample evidence that the dams have reduced the amount of sediments flowing from the rivers into the bays.

In addition, there is a growing body of evidence that sea level will increase more rapidly in the 21st Century than it has in several thousand years.

Based on marine sedimentary records, oceanographers know that sea level has been rising for the past 10,000 years, but the rate at which it's rising has been slowly falling for about 5,000 years. But that trend is apparently changing, with the latest satellite data indicating that seas worldwide are rising at an average rate of five millimeters per year – a striking contrast to the rate of two millimeters per year that was recorded by tide gauges throughout most of the 20th Century.

In some locations, warming water temperatures, land subsidence and other factors can exert a local influence, causing sea level to rise even faster. This also appears to be the case along the Texas-Louisiana coast, which is sinking by an average of two millimeters per year, and up to twice that much in certain areas.

"Bay-head deltas are just like the wetlands that have been disappearing in southeastern Louisiana in recent decades," Anderson said. "They have to be renewed with river-borne sediments in order to maintain themselves in the face of steadily rising seas."

Anderson said the geological record shows that sediment flowing into the five bays has tended to just keep pace with rising sea level over the past 10,000 years. The flooding events mark points in time when this delicate balance was upset. The most dramatic event occurred in Galveston Bay between 7,300-7,100 years ago. In that geological instant, the boundary between river and bay receded about 35 kilometers upstream.

"At that time, the head of the bay was somewhere north of I-10, but sediments flowing back into the bay from the Trinity River pushed that back south to the present location, creating Lake Anahuac in the process," Anderson said. "The creation of Lake Livingston and other lakes on the Upper Trinity has significantly reduced the amount of sediments flow into the bay, and data collected by the Texas Bureau of Economic Geology and the United States Geological Survey indicate that the headland marshes are teetering on the brink."

Jade Boyd | EurekAlert!
Further information:
http://www.rice.edu

More articles from Earth Sciences:

nachricht Tiny microenvironments in the ocean hold clues to global nitrogen cycle
23.04.2018 | University of Rochester

nachricht Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>