Role of salt-marsh erosion in barrier island evolution and deterioration in coastal Louisiana
- Louisiana Universities Marine Consortium, Chauvin (USA)
Barrier shoreline erosion in Louisiana reaches over 10 m/year, and island area decreased by 40% between 1880 and 1979. Salt-marsh erosion is an important factor in evolutionary barrier shoreline development and is presently contributing, both directly and indirectly, to the deterioration of Louisiana's barrier islands. The marshes originally developed as fresh marshes associated with regression of Mississippi River delta lobes. After abandonment, salinity gradually increased and natural habitat change occurred as subsidence of deltaic sediments and transgression of the coastline by marine processes proceeded. The marsh surface is subjected to relative sea level rise and unless there is sufficient sedimentation to maintain marsh elevation, erosional processes become dominant. Increased inundation of marsh vegetation stresses even halophytic vegetation and leads to plant death. Examination of variations in marsh topography over an area of approximately 1 ha. revealed marked variations in the frequency and duration of tidal inundation. Increased flooding of lower areas can be sufficient to cause plant death and the opening of marsh ponds. As small ponds expand and coalesce to form larger areas of open water, wave action becomes important in eroding pond banks and mobilizing sediment from the bed causing pond deepening. Fragmentation of the marsh by these subsidence-induced processes is part of the evolution of morphostratigraphic forms in the Mississippi deltaic plain from erosional headland with flanking barriers to barrier island arc.
- OSTI ID:
- 5140738
- Report Number(s):
- CONF-8910221-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 73:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM meeting, Corpus Christi, TX (USA), 25-27 Oct 1989; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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