Rapid subsidence and historical wetland loss in the Mississippi Delta Plain: likely causes and future implications

iv Figures Figure 1. Regional map of south-central Louisiana showing locations of coring sites, boundaries of areas used for image analysis of land-water changes, and subdeltas of the Lafourche delta system.. Figure 2. Regional map of south-central Louisiana showing locations of coring sites, the USACE Cocodrie tide gauge, the LDNR Montegut tide gauge, and the distribution of wetland losses (1956-2004) relative to producing oil-and-gas fields .. Figure 3. Composite historical land-water changes between 1956 and 2004 for the selected study areas in south-central Louisiana, with daily, 3-day, and 7-day average water levels recorded at the NOS Figure 6. Locations of sediment cores and sediment-surface profiles from the Bay St. Elaine area superimposed on pre-and post-subsidence aerial photographs taken in (A) 1969, (B) 1974, and Figure 7. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores illustrate the magnitude of subsidence (in cm) at the Bay St. Figure 9. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores MB-10 to MB-07 illustrate the magnitude of subsidence and wetland erosion (in cm) Figure 10. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores MB-10 to MB-08 illustrate the magnitude of subsidence and wetland erosion (in cm) at the Figure 11. Locations of sediment cores and sediment-surface profiles from the DeLarge area superimposed on pre-and post-subsidence aerial photographs taken in (A) 1969, (B) 1974, Figure 12. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores illustrate the magnitude of subsidence and wetland erosion (in cm) at the DeLarge Figure 14. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores illustrate the magnitude of subsidence and wetland erosion (in cm) at the Pointe au Figure 15. Locations of sediment cores and sediment-surface profiles from the Bully Camp area superimposed on pre-and post-subsidence aerial photographs taken in (A) 1969, (B) 1974, and v Figure 16. Combined bathymetric profile and stratigraphic cross section for marsh and open-water cores illustrate the magnitude of subsidence and wetland erosion (in cm) at the Bully Camp Table 5. Minimum subsidence rates inferred from minimum aggradation rates based on marsh thickness (interval rate) and sample depth (depth rate). Table 6. Rates (mm/yr) of sediment accumulation (sed) and inferred rates of subsidence (sub) for the 1 Summary Five representative areas of the Mississippi River delta plain were investigated using remote images, marsh elevations, water depths, sediment cores, …

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