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Spring 2007
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Mobile GIS Maps Derelict and Sunken Vessels Along the Coast of Georgia

Web-Based Maps Encourage Safe Navigation of Waterways

By Charles "Buck" Bennett, Coastal Resources Division, Georgia Department of Natural Resources

Highlights

  • Online maps keep the boating public informed.
  • ArcPad mobile GIS used for on-site mapping.
  • Georeferenced imagery lets users visualize hazards.
  click to enlarge
Red and black anchor symbols indicate the locations of sunken vessels in Turner Creek and the Wilmington River, Chatham County, Georgia.

The Georgia Department of Natural Resources (DNR) has been struggling with mapping abandoned and derelict vessels for several years. Based on recent estimates, there are as many as 100 sunken vessels along the coast of Georgia that are potential hazards for boaters. On the state's tidal water bottoms, 65 abandoned or derelict vessels have been identified as nonhistoric wrecks (vessels that have no significant historical value). These vessels include shrimp boats, abandoned recreational vessels, barges, and cranes. Recently, DNR's Coastal Resources Division began the task of locating, documenting, and cataloging these nonhistoric wrecks with GIS.

The division is also leading the public information effort in Georgia to make citizens aware of these vessels' locations via its Web site (www.gadnr.org). The GIS interface on the site will serve as a conduit between survey data from the field and stakeholders interested in the survey results. The Web site will be regularly updated to keep the boating public informed of these coastal hazards to minimize the risk of collision and injury.

Improving Debris Removal

It often becomes the government's responsibility to remove vessels that have been abandoned in waterways. In many cases, the owners of the sunken vessels cannot be found or ownership cannot be proved. Since sunken vessels are not usually covered under insurance policies, those boat owners who can be identified frequently lack the financial ability to retrieve the vessel. Owners escape financial responsibility through bankruptcy laws or a clause in federal maritime law that limits an owner's liability to the value of the ship and its contents. Since most abandoned vessels are valueless, the owner's liability would be zero.

During the 2006 legislative session, monies were appropriated by the Georgia legislature to remove some of these derelict vessels. A team was formed that includes members of DNR's Coastal Resources Division, Environmental Protection Division, and the Wildlife Resources Division Law Enforcement Section to catalog, evaluate, and prioritize the vessels for removal. To facilitate and more accurately document the location of these nonhistoric derelict vessels, DNR applied for the Esri and Trimble Mobile Government Grant: Coastal Communities Edition.

Upon receipt of the Trimble GeoXH 2005 Series Pocket PC and ArcPad software, staff conducted a survey of Turner Creek in Chatham County near Savannah, Georgia. Turner Creek has become extremely congested with recreational sailboats, recreational fishing boats, and derelict vessels. Along a quarter-mile section of Turner Creek, there are two known wrecks, one derelict fishing vessel, a public boat ramp with dock, and no less than seven anchored recreational sailboats, along with a large marina, charter fishing docks, and a dry dock facility. This popular area of Turner Creek was the ideal location to begin collecting information and working with the equipment.

Mobile Mapping

In preparation for on-site mapping, the DNR team loaded ArcPad into the GeoXH 2005 Series Pocket PC and customized ArcPad with a pull-down menu containing the various information cells that would need to be collected in the field. The mobile GIS unit was carried into the field and placed on the deck of the small research vessel or was hand-carried into the marsh and/or tributary to accurately mark the location of the sunken or derelict vessel. Information was entered through the drop-down menus on the Pocket PC.

  photo of sunken vessel
Sunken fishing vessel in Doboy Sound, McIntosh County, Georgia (photo courtesy of Paul Christian, University of Georgia, Marine Extension Service).

Because of the large size of the TIFF files, staff members uploaded only those sections of coastal county maps necessary to conduct the survey of the project waterway. After collecting the data, staff members would download the updated point shapefiles into ArcGIS Desktop software at the office. A two-gigabyte secure digital card was added to the Pocket PC to enable the use of additional TIFF files. Photographs or side-scan sonar images were made of various wrecks to be used on the Web site to allow boaters to see the water hazard as it exists. Because some of the derelict vessels have sunk in deep water and are not exposed, side-scan images are being used to enhance wreck site awareness.

These digital photos are accessible via a link on the ArcIMS software-based Web site (www.gadnr.org). Additional information, such as impact to marsh vegetation from the vessel itself or from fuel and oil leaks, will be collected. This information will be analyzed using ArcGIS Desktop software and available on the site to staff making decisions regarding the removal of these derelict nonhistoric wrecks. The site also will include a description of the marine debris, the location, and condition.

The handheld Trimble GeoXH Pocket PC allowed staff to quickly collect the GPS coordinates, log the information, and move to the next subject location. The Coastal Resources Division plans to continue to use the mobile GIS and georeferenced photographs in its fieldwork. This handheld technology significantly reduced the in-the-field mapping time and has created much more accurate information than could have been achieved with manual field mapping methods or simply utilizing georeferenced aerial photographs alone.

Through the use of newspaper articles, departmental publications, and personal contacts, the State of Georgia has also recruited local boaters and charter fishermen to help identify additional wrecks or derelict vessels.

The general public can access the sunken vessel data through the Georgia Department of Natural Resources Web site. The site will be updated regularly to add or remove derelict and sunken vessels. The project assists staff, local governments, and possibly federal agencies in assessing marine debris as it relates to navigation, fishing, and environmental impacts.

About the Author

Charles "Buck" Bennett has been employed by the State of Georgia for 18 years. He served as the Habitat Program manager and most recently as the Compliance and Enforcement manager for the Coastal Resources Division, Georgia Department of Natural Resources, in Brunswick, Georgia. He gained most of his experience in using georeferenced software and global positioning systems while serving in the military during deployments to Bosnia and Iraq.

More Information

For more information, contact Charles "Buck" Bennett, Compliance and Enforcement manager, Coastal Resources Division, Georgia Department of Natural Resources (tel.: 912-264-7218, e-mail: buck_bennett@dnr.state.ga.us). This application, along with those from other grant winners, is available on Esri's public domain Web site at www.esri.com/arcscripts.

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