See more from this Division: Joint Sessions
See more from this Session: Land Subsidence Attributable to Subsurface Fluid Extraction in Coastal Lowlands: Contributions to Relative Sea-Level Rise
Abstract:
Many processes other than subsidence (e.g., direct removal, storms) can also convert wetlands to open water, but subsidence accounts for much of the extensive interior wetland losses in the Mississippi delta plain that occurred during the 1960s and 1970s. During this period, subsidence rates were an order of magnitude greater than rates averaged over geological time scales (millennia). Natural internal basin processes such as deep-seated salt mobilization and fault movement cannot be ruled out entirely, but there is no compelling evidence that these processes were responsible for the observed changes. In fact, repeat leveling surveys show historical subsidence over salt domes rather than uplift, as expected. Furthermore, it would be difficult to explain the recent reductions in subsidence rates if rapid subsidence were related to tectonic processes.
Former delta-plain marshes are now submerged beneath water that averages 0.5 to 1.0 m deep. Although magnitudes of subsidence are not large relative to other examples of production-induced subsidence, minor reductions in elevation result in extensive permanent submergence when coastal wetlands are near sea level.
See more from this Division: Joint Sessions
See more from this Session: Land Subsidence Attributable to Subsurface Fluid Extraction in Coastal Lowlands: Contributions to Relative Sea-Level Rise