Abstract:
The Coastal and Marine Geology Program of the U.S. Geological Survey has
generated a comprehensive database of digital vector shorelines and shoreline
change rates for the U.S. Gulf of Mexico. These data, which are presented
herein, were compiled as part of the U.S. Geological Survey's National
Assessment of Shoreline Change Project. Beach erosion is a chronic problem
along most open-ocean shores
... of the United States. As coastal populations
continue to grow and community infrastructures are threatened by erosion, there
is increased demand for accurate information including rates and trends of
shoreline migration. There is also a critical need for shoreline change data
that is consistent from one coastal region to another. One purpose of this work
is to develop standard repeatable methods for mapping and analyzing shoreline
movement so that periodic updates regarding coastal erosion and land loss can
be made nationally that are systematic and internally consistent.
This data compilation for open-ocean, sandy shorelines of the Gulf of Mexico is
the first in a series that will eventually include the Atlantic Coast, Pacific
Coast, and parts of Hawaii and Alaska. Short- and long-term shoreline change
evaluations are based on merging three historical shorelines with a modern
shoreline derived from lidar (light detection and ranging) topographic surveys.
Historical shorelines generally represent the following time periods: 1800s,
1920s-1930s, and 1970s. The most recent shoreline is derived from data
collected over the period of 1998-2002. Long-term rates of change are
calculated by linear regression using all four shorelines. Short-term rates of
change are simple end-point rate calculations using the two most recent
shorelines. Please refer to our full report on shoreline change in the Gulf of
Mexico, National Assessment of Shoreline Change: Part 1, Historical Shoreline
Changes and Associated Coastal Land Loss Along the U.S. Gulf of Mexico (USGS
Open File Report 2004-1043) for additional information regarding methods and
results.
Data in this report are organized into data layers by state and are provided as
single-point vector datasets with metadata. Vector shorelines may represent a
compilation of data from one or more sources and these sources are attributed
in the dataset. All data are intended to be GIS-ready inasmuch as the data
should not require any additional cleanup, formatting, or renaming of fields in
order to use the data in a Geographic Information System (GIS). This project
employs the Environmental Systems Research Institute's (ESRI) ArcView as its
GIS mapping tool and contains several data layers (or themes) that are used to
create a geographic view of the margin off the U.S. Gulf of Mexico. These
vector data form a basemap comprised of polygon and line themes that include a
U.S. coastline (1:80,000), U.S. cities, and state boundaries.
[Summary provided by the USGS.]