Coastal Services Center

Mapping coastal vegetation such as salt marsh or seagrass beds using satellite imagery or aerial photography can be expensive and may require specialized training. Researchers at a Washington State National Estuarine Research Reserve have developed low-budget mapping methodologies that can be used by state and local coastal planners challenged by limited budgets or technology.

Coastal and submerged aquatic vegetation are "critical and important components of estuarine and coastal ecosystems," notes Suzanne Shull, geographic information system (GIS) specialist at the Padilla Bay Reserve. "Coastal resource managers and their staff increasingly are being called on to protect and enhance these communities and in the process are expected to map their location."

In 2000, Shull and Reserve Research Coordinator Douglas Bulthuis developed and tested a methodology for mapping and monitoring coastal vegetation using aerial photography, desktop computers, and the cheapest ESRI ArcView software available at the time. In 2004, they updated the methodology to reflect rapidly changing and more affordable technologies.

"We would like to stimulate coastal managers," Shull says. "In 2000, people were not using GIS as prolifically as they are now, and we wanted to show that this can be done, first of all, and second of all, it can be done without a lot of investment in high-end software or training."

The methodologies can be used for restoration projects, invasive species control, land-use planning, and resource management. Interest in the methodologies has come from as far away as South Africa and Britain.

The methodologies were developed, tested, documented, and demonstrated by mapping salt marsh, macroalgae, and two species of eelgrass in the Padilla Bay Reserve. The multi-step methodologies conform to many of the recommendations in the national benthic habitat mapping guide developed by the National Oceanic and Atmospheric Administration's Coastal Services Center.

Padilla Bay's 2000 methodology, which was funded by the Cooperative Institute for Coastal and Estuarine Environmental Technology (CICEET), includes procurement of aerial photography, ground truth sampling, obtaining rectified reference photographs, scanning the photos, georectifying the photos, mosaicking, photointerpretation, on-screen digitizing, and developing vegetative cover GIS polygons.

The 2004 methodology was developed as part of the National Estuarine Research Reserve System's pilot biomonitoring project. The primary difference in the methods was the purchase of georectified orthophotography. The methodology includes image acquisition, image processing, classification schema and geodatabase construction, ground reference data, on-screen delineation, quality assurance/quality control checking of the data, and change detection between 2000 and 2004.

While technology has evolved, Shull says "elements of the 2000 methodology are still quite useful." The methodology is still being used by managers who "can't afford anything else."

She adds, "Our methods are affordable, repeatable, and have the resolution and accuracy standards needed by local coastal managers."

To access the methodology papers developed by Padilla Bay National Estuarine Research Reserve, point your browser to www.padillabay.gov/map_projects.asp. You may also contact Suzanne Shull at (360) 428-1092, or sshull@padillabay.gov. For more information on Guidance for Benthic Habitat Mapping: An Aerial Photographic Approach, go to www.csc.noaa.gov/benthic/.