Depicting Coastal Louisiana Land Loss

Coastal Louisiana Land Loss Map

The Coastal Louisiana Land Loss map depicts historical 

(1932-2000) changes of land to water and water to land, 

as well as projected changes (2000-2050). Projections are 

based on the assumption of no future restoration. 

Source of Data

The U.S. Army Corps of Engineers provided the 1932 land 

and water data derived from U.S. Geological Survey (USGS) 

15-minute topographic maps. The 2000 land and water 

conditions are based on classified Landsat Thematic Mapper 

satellite imagery provided by the USGS. 

Methodology for Calculating Historical

Land Change

The USGS compared the 1932 land and water data to the 2000 

land and water data by using geographic information system 

software to identify land areas from 1932 that had converted to 

water (“land loss”) or water areas from 1932 that had converted 

to land (“land gain”) by the year 2000. In the map depiction, the 

vast areas of historical land loss appear in red, while the much 

smaller areas of historical land gain are in light green. 

The small areas of land gain are present both in the Atchafalaya 

Delta and as scattered dredged materials that have been put to 

beneficial use in various projects.

Methodology for Calculating Projected

Land Change

Land losses projected for the years 2000 to 2050 are depicted 

as yellow areas, while projected 2000 to 2050 land gains 

appear as deep green areas. The land loss and gain predictions

are based on projecting historical 1978 to 2000 land-water 

changes 50 years into the future for similar loss areas that 

were identified by a trend analysis workgroup consisting 

of multiagency Federal technical personnel and university 

researchers. The 1978 to 2000 period is believed to more 

accurately portray current coastal Louisiana trends in land 

change than does the 1932-2000 period. Adjustments were 

made to the 2000-2050 land and water projections to account 

for benefits from constructed wetland restoration projects prior 

to 2000. Developed and agricultural areas were excluded from 

the loss-gain projections. This methodology was developed 

and reviewed in conjunction with partners from the U.S. 

Fish and Wildlife Service, U.S. Army Corps of Engineers, 

National Oceanic and Atmospheric Administration, Natural 

Resources Conservation Service, Environmental Protection 

Agency, Louisiana Department of Natural Resources, and many 

Louisiana universities.

U.S. Department of the Interior Fact Sheet 2005-3101

U.S. Geological Survey July 2005
Documentation

The USGS Open-File Report 03-334 “Historical and 

Projected Coastal Louisiana Land Changes: 1978-2050” explains in detail the above methodology. The report can 

be found at http://www.lca.gov/appb.aspx, and digital 

copies of land change maps can be downloaded from 

http://www.nwrc.usgs.gov/special/landloss.htm.

Southeastern Louisiana Land Loss Map

In addition to the map described above, a map has been 

produced of only the southeastern part of coastal Louisiana, 

where land loss is most pronounced. In this second map, 

red is used to show both historical and projected loss.

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For more information, contact

regory J. Sm th, Ph.D.

U.S. Geo og ca Survey

Nat ona Wet ands Research Center

700 Ca undome B vd.

Lafayette, LA 70506

337-266-8501

ttp: www.nwrc.usgs.gov