Fig 1.
Photographic montage of canals and spoil banks.
A. The Leeville, La, oil field with a mosaic of canals, wetlands and open water in 1989. The yellow vertical bar over Catfish Lake is 2 km. B. A canal that is not backfilled at the keyhole in the bottom of the picture, but is backfilled towards its entrance. C. A canal before being backfilled. D. The canal in C, after it was backfilled. The keyhole is the enlarged terminal end on the right of the dredged channel. A white outline of the shape of the spoil bank area is shown. The average width of the canals is about 33 m. Photo credits: A is a Landsat image sourced from the U.S. Geological Survey EarthExplorer (http://earthexplorer.usgs.gov/) and is freely available public domain data [4]. B-D are by the co-authors.
Fig 2.
The rise in various kinds of oil and gas drilling permits in the 12 parishes of south Louisiana.
A. The total permits, those labeled as abandoned or plugged in the permit files, the permits issued for land/wetland, and the land/wetland permits that are labeled as abandoned or plugged in the permit files. B. The cumulative percent of permits that are labeled abandoned and plugged by that year. C. The peaks in permit number and the oil and gas production (normalized). D. The percent of all permits issued each year and the % for land/wetland activity.
Fig 3.
The distribution of oil and gas well permits issued between 1900 and 2017 that were ‘plugged’ or ‘abandoned’ in 2017 and on land in the 14 parishes.
Fig 4.
The number of oil and gas permits issued annually and the land loss rates.
B. The land loss rate from the 1930s to 1990 and canal density in 15 minute quadrangle maps.
Fig 5.
Changes in the width of backfilled and reference canals that were >200 m long in 1992.
A: Widths of backfilled and reference canals in 1998, 2004, 2010 and 2017. B: Restoration from 1998 for backfilled canals versus the depth of the water in 1992 that were had plugs visible in the imagery. The means ± 1 SEM are shown.
Fig 6.
The canal area in coastal Louisiana for 5 dates from 1933 to 1990 and the cumulative permits issued by then.
A simple linear regression of the data is shown.