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Quantitative Evaluation of Regional Subsidence Processes Contributing to Rapid Sea Level Rise and Wetland Loss in the Mississippi River Delta Plain, Louisiana: Timothy A. Meckel
Project Title: Quantitative Evaluation of Regional Subsidence Processes Contributing to Rapid Sea Level Rise and Wetland Loss in the Mississippi River Delta Plain, Louisiana
Mendenhall Fellow: Timothy A. Meckel, (508) 457-2537, tmeckel@usgs.gov
Duty Station: Woods Hole, MA
Start Date: June 1, 2004
Education: Ph.D. (Geosciences), The University of Texas at Austin, 2003
Research Advisor: Jeff Williams, (508) 457-2383, jwilliams@usgs.gov; Uri ten Brink, (508) 457-2396, utenbrink@usgs.gov

Project Description: Relative sea level rise in south central Louisiana during the last 50 years has averaged about 1 cm/yr (10 times the global average) due to a complex combination of natural and anthropogenic factors operating on regional and global scales.  Such dramatic subsidence in historical times has been cited as a leading cause of rapid wetland loss in coastal Louisiana, which impacts the regional socio-economic infrastructure.  In order to adequately anticipate and strategically mitigate the environmental and societal impacts of marine transgression regionally, thorough understandings of the dominant natural processes that influence subsidence are needed.

Subsidence and resulting rapid sea level rise in Louisiana has been attributed to natural (isostatic sediment loading, sediment compaction, dewatering) and human (subsurface fluid withdrawal) factors, but quantitative estimates of the relative contributions of each of these factors are lacking and their role in future subsidence is largely unknown.  The time scales and geographic extent of each of these processes is variable.  This research focuses on the component of subsidence related to the isostatic response of the coastal margin to Pleistocene and Holocene loads (<150,000 yrs).  

Through numerical modeling of the dynamic response to sedimentary loads, we intend to quantify the amount of regional subsidence that may be a response to variable regional depositional patterns.  It is important to establish whether the coastal plain is in equilibrium with depositional loads, or still responding. Identifying the viscoelastic response of the continental margin to sediment isopach maps over time is a specific goal of the modeling component.  Additionally, we intend to integrate historical estimates of rates of elevation change with our modeling results.  All of the more local, shorter time-scale processes can then be interpreted in this context.

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