Microtidal marsh loss with accelerating sea level rise in the Gulf of Mexico: Running with Alice
Data files
May 22, 2026 version files 41.75 KB
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dryad_land_loss_data_2.xlsx
38.73 KB
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README.md
3.02 KB
Abstract
Global sea level rise (SLR) is a widely appreciated threat to coastal wetlands. Modeled estimates of SLR thresholds beyond which coastal wetlands convert to open water suggest that landscape scale estimates of wetland loss vary with geomorphic setting, upland barriers to migration, vegetative tolerances to flooding, sediment supply, and tidal ranges among others. Landscape scale examples from long-term observations are sparsely available but needed to interpret the significance of data collected from small and large sampling plots, after occasional storms, of various observation lengths, and regional SLR variations. A long-term data set from the northern Gulf of Mexico is available to evaluate some of these threshold factors. Dredging for canals is the dominant stressor for losing 17% of the 21,884 km2 of microtidal coastal lands existing in 1934. There is a strong linear relationship between dredging canals and land loss from 1934 to 1990. Compared to 1980 to 1999, SLR in the GOM doubled from 2000 to 2022 at a steady 10 mm y-1. This recent doubling presented an opportunity to test if there was a SLR impact effect on land loss vs. canal density from 1934 to 2016 compared to from 1934 to 1990. No acceleration in the slope or change in intercept was observed as SLR accelerated and there was a coincidental rise and fall in both coastal land loss and the number of dredging permit issued in the last 95 years. We conclude that a 10 mm y-1 SLR has not (yet) become a synergistic stressor on wetland loss on this coast, where human-driven effects on land loss continue to accumulate. We anticipate that the legacy effect of canal dredging will eventually work synergistically with SLR to accelerate the rate of land loss.
Dataset DOI: 10.5061/dryad.w0vt4b979
Description of the data and file structure
We investigated if land loss in coastal Louisiana increased as a result of the recent rise of global sea level rise to 10 mm y-1. A long-term data set from the northern Gulf of Mexico was assembled to evaluate if the relationship of land loss to dredged canals, a dominant cause of land loss, changed from 1990 to 2016 with this rise in sea level rise. Data on cumulative land loss from 1934 to 1990 and canal density were assembled and canal density in 2016 estimated using permit records in public records. The data are available for unrestricted use.
Files and variables
File: dryad_land_loss_data_2.xlsx
Description:
- Worksheet ‘FIG. 3 permits#’ contains data for Fig. 3. Number of oil and gas permits issued from 1991 to 2016 compared to the permits issued from 1900 to 1990 for individual 15’ quadrangles.
- Worksheet ‘FIG. 4 land area by interval’ contains data for Fig. 4. Land area in each quadrangle map estimated by USGS (Couvillon et al. 2017) or Britsch and Dunbar (1993). A) 1990 compared to 1990; B) 1985 compared to 1983; C) 1974 compared to 1973; D) 1958 compared to 1956; E) 1974 compared to 1973. All maps with full coverage in 15 minute quadrangles are included.
- Worksheet ‘FIG. 5 land loss>50%’ contains data for Fig. 5. Cumulative percent canal density and cumulative percent land loss in quadrangles with <50% land. A) from 1934 to 1990. B) from 1934 to 2016.
- Worksheet ‘FIG. 6 land loss < 50%’ contains data for Fig. 6. Cumulative percent canal density and cumulative percent land loss in quadrangles with <50% land. A) from 1934 to 1990. B) from 1934 to 2016.
- Worksheet ‘FIG. 8 near river’ contains data for Fig. 8. % land loss and % canal density in 15’quadrangles that have part of the Mississippi River channel in them and outside of them.
- Worksheet ‘FIG. 9 O&G permits and land loss‘ contains data for Fig. 9. Annual number of oil and gas permits issued and land loss for different intervals for all coastal quadrangles analyzed by Britsch and Dunbar (1993) and the updated land loss rates from 1990 to 2016.
Variables
- See sheets "Readme" and "units, methods used" in data file.
Code/software
Microsoft Excel Workbook (.xlsx)
Access information
Other publicly accessible locations of the data:
Data was derived from the following sources:
- from either Britsch and Dunbar 1993, or Couvillon 2017 (Britsch LD, Dunbar JB (1993) Land loss rates: Louisiana coastal plain. J Coast Res 9:324–338. OR Couvillion BR, Beck H, Schoolmaster D, Fischer M (2017) Land area change in coastal Louisiana (1932 to (2016). Pamphlet to accompany U.S. Geological Survey Scientific Investigations Map 3381)