HR: 0800h
AN: G51A-0133    [Abstracts]
TI: Peat Compaction as a Premier Driver of Mississippi Delta Subsidence
AU: * Tornqvist, T E
EM: tor@tulane.edu
AF: Department of Earth and Environmental Sciences, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118-5698, United States
AU: Wallace, D J
EM: djw1@rice.edu
AF: Department of Earth and Environmental Sciences, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118-5698, United States
AU: Blaauw, M
EM: martijn.blaauw@shell.com
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Derksen, M S
EM: m.s.derksen@minlnv.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Klerks, C J
EM: k.klerks@vestigia.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Meijneken, C
EM: camiel.meijneken@prorail.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Snijders, E M
EM: els.snijders@minvrom.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Storms, J E
EM: j.e.a.storms@citg.tudelft.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: van Dam, R L
EM: rvd@msu.edu
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AU: Wallinga, J
EM: j.wallinga@tudelft.nl
AF: Department of Physical Geography, Utrecht University, P.O. Box 80115, Utrecht, NL-3508 TC, Netherlands
AB: The adverse consequences of coastal subsidence (accelerated relative sea-level rise, shoreline erosion, and wetland loss) and its threats to coastal populations are widely recognized. The Mississippi Delta has become the poster child of coastal hazard following the devastation from Hurricane Katrina, partly attributed to the loss of vast wetlands that could have served as a buffer against storm surge. Several recent studies have focused on the wide variety of components that are believed to contribute to subsidence in the Mississippi Delta and adjacent coastal Louisiana, ranging from lithospheric processes to the compaction of relatively shallow materials. Current estimates of subsidence rates in this area differ by several orders of magnitude. While compaction of Holocene strata is widely believed to be an important contributor to subsidence, surprisingly little is known about compaction rates over centennial to millennial timescales, whether in coastal Louisiana or elsewhere. Measurements of the deformation of a 1500-year-old, originally near-horizontal swamp peat bed in the Mississippi Delta shows that averaged peat compaction rates can be as high as 5 mm/yr, values that exceed recent model predictions. It is conceivable that over decadal to centennial timescales compaction rates can locally be 10 mm/yr or more. Compaction is capable of accounting for a large portion of the exceptionally high rates of land surface subsidence, relative sea-level rise, and coastal wetland loss in the Mississippi Delta, and it is likely a significant cause of subsidence in organic-rich, low-lying coastal plains elsewhere.
DE: 1105 Quaternary geochronology
DE: 1211 Non-tectonic deformation
DE: 1890 Wetlands (0497)
DE: 4556 Sea level: variations and mean (1222, 1225, 1641)
DE: 6334 Regional planning (1880)
SC: Geodesy [G]
MN: 2007 Fall Meeting