Geomorphology and depositional subenvironments of Gulf Islands National Seashore, Mississippi

Open-File Report 2009-1250
Prepared in cooperation with the National Park Service (NPS).
By:  and 



The U.S. Geological Survey (USGS) is studying coastal hazards and coastal change to improve our understanding of coastal ecosystems and to develop better capabilities of predicting future coastal change. One approach to understanding the dynamics of coastal systems is to monitor changes in barrier-island subenvironments through time. This involves examining morphological and topographic change at temporal scales ranging from millennia to years and spatial scales ranging from tens of kilometers to meters. Of particular interest are the processes that produce those changes and the determination of whether or not those processes are likely to persist into the future. In these analyses of hazards and change, both natural and anthropogenic influences are considered. Quantifying past magnitudes and rates of coastal change and knowing the principal factors that govern those changes are critical to predicting what changes are likely to occur under different scenarios, such as short-term impacts of extreme storms or long-term impacts of sea-level rise. Gulf Islands National Seashore was selected for detailed mapping of barrier-island morphology and topography because the islands offer a diversity of depositional subenvironments and the islands' areas and positions have changed substantially in historical time. The geomorphologic and subenvironmental maps emphasize the processes that formed the surficial features and also serve as a basis for documenting which subenvironments are relatively stable, such as the beach ridge complex, and those which are highly dynamic, such as the beach and active overwash zones. The primary mapping procedures used supervised functions within a Geographic Information System (GIS) that classified depositional subenvironments and features (map units) and delineated boundaries of the features (shapefiles). The GIS classified units on the basis of tonal patterns of a feature in contrast to adjacent features observed on georeferenced aerial photographs. Land elevations from recent lidar surveys served as supplementary data to assist in delineating the map-unit boundaries.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Geomorphology and depositional subenvironments of Gulf Islands National Seashore, Mississippi
Series title Open-File Report
Series number 2009-1250
DOI 10.3133/ofr20091250
Year Published 2010
Language English
Publisher U.S. Geological Survey
Contributing office(s) St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey
Description 4 Plates: 34.00 x 44.00 inches; Metadata
Country United States
State Mississippi
Other Geospatial Cat Island, Horn Island, Petit Bois Island, Ship Island
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details