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Delta lobe degradation and hurricane impacts governing large-scale coastal behavior, South-central Louisiana, USA

Geo-Marine Letters

By:
, , , ,
DOI: 10.1007/s00367-009-0156-4

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Abstract

A large deficit in the coastal sediment budget, high rates of relative sea-level rise (???0.9 cm/year), and storm-induced current and wave erosion are forcing barrier shoreface retreat along the periphery of the Mississippi River delta plain. Additionally, conversion of interior wetlands to open water has increased the bay tidal prism, resulting in degradation of barrier islands due to inlet widening, formation of new inlets, and sediment sequestration at ebb-tidal deltas. Single-beam bathymetric surveys along a 165-km stretch of south-central Louisiana barrier coast, from Raccoon Point in Terrebonne Parish to Sandy Point in Plaquemines Parish, were conducted in 2006. These data, combined with historical bathymetry from three time periods (dating to the 1880s), provide a series of digital elevation models that were used to calculate sediment volumetric changes and determine long-term erosional-depositional trends. Dominant patterns during the 125-year period include (1) erosion of ???1.6????????109 m3 from the shoreface, forcing up to 3 km of shoreface retreat, (2) sediment deposition in coastal bights and at ebb-tidal deltas, and (3) a combined increase in tidal inlet cross-sectional area from ???41,400 m2 to ???139,500 m 2. Bathymetric and shoreline change datasets separated by shorter time periods (sub-annual) demonstrate that these long-term trends are driven by processes associated with major hurricane impacts, and that rates of shoreface erosion are an order of magnitude greater during active hurricane seasons compared to long-term trends. ?? 2009 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Delta lobe degradation and hurricane impacts governing large-scale coastal behavior, South-central Louisiana, USA
Series title:
Geo-Marine Letters
DOI:
10.1007/s00367-009-0156-4
Volume
29
Issue:
6
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geo-Marine Letters
First page:
441
Last page:
453
Number of Pages:
13