Originator: U.S. Geological Survey
Assateague Island Sand Areas Extracted from Orthoimagery, 1989 - 2013
Geospatial_Data_Presentation_Form: vector digital data
Series_Name: U.S. Geological Survey Data Series
Publication_Place: St. Petersburg, Fla.
Publisher: U.S. Geological Survey
Assessing the physical change to shorelines and wetlands is critical in determining the resiliency of wetland systems that protect adjacent habitat and communities. The wetland and back-barrier shorelines of Assateague Island, located in Maryland and Virginia, changed as a result of wave action and storm surge that occurred during Hurricane Sandy, which made landfall on October 29, 2012. The impact of Hurricane Sandy will be assessed and placed in its historical context to understand the future vulnerability of wetland systems.
Making these assessments will rely on data extracted from current and historical resources such as maps, aerial photographs, satellite imagery, and lidar elevation data, which document physical changes over time.
This USGS Data Series publication includes several open-ocean shorelines, back-island shorelines, back-island shoreline points, sand area polygons, and sand lines for Assateague Island that were extracted from orthoimagery (ortho aerial photography) dated from April 12, 1989 to September 5, 2013.
This dataset consists of polygons that represent the sand areas found in orthoimagery taken on the date specified in the filename and in the Date_ field in the feature attribute table.
Orthoimagery of Assateague Island were acquired in digital format from U.S. Department of Agriculture (USDA), U.S. Geological Survey (USGS) and Virginia Geographic Information Network (VGIN) courtesy of the Commonwealth of Virginia. Prior to processing, the images were trimmed to the Assateague Island area. Using ERDAS Imagine 9.3, the images were classified into 10-40 classes that were coded either sand or not sand. Using ArcGIS 10.1, the resulting coded raster datasets were converted to polygons and edited.
The following list provides additional details about the orthoimagery used. The sand areas for each date is in a separate dataset (shapefile) named asis_sand_po_*.shp where the date, in YYYYMMDD format, replaces the asterisk. The orthoimage date for each polygon is also included in the shapefile attribute table Date_ field.
Date State Type Source Resolution
198904129(1) MD DOQQ USGS 1 meter (m)
19940320 VA DOQQ USGS 1 m
20041105 VA NAIP USDA 2 m
20050608 VA NAIP USDA 2 m
20050615 MD NAIP USDA 1 m
20060528 VA NAIP USDA 2 m
20060701 MD NAIP USDA 2 m
20070622 MD NAIP USDA 1 m
20080525 VA NAIP USDA 1 m
20090626 MD NAIP USDA 1 m
20090726 VA NAIP USDA 1 m
20090807 VA NAIP USDA 1 m
20110530 VA NAIP USDA 1 m
20110602 MD NAIP USDA 1 m
20120512 VA NAIP USDA 1 m
20130315 VA VBMP VGIN(2) 1 m(3)
20130905 MD NAIP USDA 1 m
DOQQ Digital Orthophoto Quarter Quads
NAIP National Agriculture Imagery Program
VBMP Virginia Base Mapping Program
(1)Color Infrared orthoimagery; all others are natural color.
(2)Imagery courtesy of the Commonwealth of Virginia.
(3)Resampled from 1-foot resolution imagery.
These data were extracted from orthoimagery to document the changes to sand areas on Assateague Island due to Hurricane Sandy and over time since 1989.
These data will aid in developing an assessment of the physical change in wetlands due to wave action and storm surge from Hurricane Sandy and in determining the resiliency of wetland systems that protect adjacent habitat and communities.
Currentness_Reference: ground condition
Maintenance_and_Update_Frequency: None planned
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: aerial photography
Theme_Keyword: remote sensing
Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)
Theme_Keyword: LAND SURFACE > LAND USE/LAND COVER > LAND COVER
Theme_Keyword: OCEAN > COASTAL PROCESSES > BARRIER ISLANDS
Theme_Keyword: COASTAL PROCESSES > BEACHES
DOI/USGS/CMG > COASTAL AND MARINE GEOLOGY, U.S. GEOLOGICAL SURVEY, U.S. DEPARTMENT OF INTERIOR
Place_Keyword: Assateague Island
Place_Keyword: United States
Place_Keyword: National Seashore
None. However, variability in image quality from one date to another, from one image to another on the same date, and from one part of a single image to another part of the same image, exists due to many factors including variation in sun angle, atmospheric conditions, season, reflectivity of the earth surface, camera angle, camera lens, camera settings, film sensitivity, water turbidity, water depth, tide level, waves, and error in image rectification. No adjustments were made to account for tide level.
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center Coastal and Marine Geology Program as the originator of these data in future products or derivative research.
Contact_Organization: U.S. Geological Survey
Contact_Person: Kristy Guy
Address_Type: mailing and physical
Hours_of_Service: Monday through Friday 9:00 AM to 5:00 PM (Eastern Time)
Address: 600 4th St. S.
City: St. Petersburg
Acknowledgment of the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center Coastal and Marine Geology Program as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.
Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.2.2.3552.