The Indicator

Total miles of shoreline are shown for the three regions grouped together, and the breakdown of different shoreline types is shown as a percentage of each region’s total shoreline miles. As discussed below, there is some double counting of shoreline types (e.g., a stretch of shoreline may be both mud flat and wetland); this occurs for only about 10% of the shoreline miles. This double counting has two minor implications for the figures. First, a sum of the miles of different types in the top graph would slightly exceed the actual miles along the shore for these three regions. Second, the values in the bottom graph represent the percentage of total shoreline length for all the types in a given region, which is somewhat more than the actual miles along the shore because of the double counting.

The Data

Data Source: These data were provided by the National Oceanographic and Atmospheric Administration (NOAA), National Ocean Service, Office of Response and Restoration, Hazardous Materials Response Division. Data on Florida’s shoreline were collected by the Florida Marine Institute and processed and interpreted by NOAA.

Data were extracted from Environmental Sensitivity Index (ESI) atlases, a product of NOAA’s Office of Response and Restoration. The ESI method provides a standardized mapping approach for coastal geomorphology as well as biological and human use elements. More information is available at http://response.restoration.noaa.gov/esi/esiintro.html. Data from multiple atlases (1984–2001) were aggregated into the regions used in this report. For most of the regions, digital data were unavailable for parts of the coastline. The currency and the completeness of the coverage affect the quality of the shoreline summary. With regard to these issues, information specific to the three regions for which data are available is presented in the “Data Quality” section below. Complete metadata for each atlas, including collection methods and source information, can be viewed at http://response.restoration.noaa.gov/esi/metadata.html.

Data Collection Methodology: ESI shoreline types were classified using a combination of overflight information, aerial photography, local habitat maps, National Wetlands Inventory data, and ground truthing. For more detailed information specific to each atlas, see the individual atlas metadata, specifically sections 5.1––Detailed Description: ESI; and 2.5.1––Source Information: ESI.

Data Manipulation: This indicator presents a simplified summary of shoreline types, by region. It is a summary of the total length of land/water interface for the region, as well as the total length of each of the five shoreline types described below.

The first step in defining the indicator was to consolidate the shorelines from the various atlases for each region and reconcile older terminology with current ESI shoreline type classifications. The next step was to combine the ESI shoreline type classes into the five more general categories, based on substrate and slope, that are used in this report. The five categories and the ESI types that make them up, are as follows:

• Steep sand, rock, or clay: ESI categories 1 (unvegetated steep banks, cliffs, and seawalls), 1A (exposed rocky shores), 2A (exposed wave-cut platforms in bedrock, mud, or clay), 2B (exposed scarps and steep slopes in clay), 3B (scarps and steep slopes in sand), and 8A (sheltered rocky shores and sheltered scarps in bedrock, mud, or clay)
• Mud or sand flats: ESI categories 7 (exposed tidal flats) and 9A (sheltered tidal flats)
• Beaches (sand or gravel): ESI categories 3AF (fine- to medium- grained sand beaches), 4 (coarse-grained sand beaches), 5 (mixed sand and gravel beaches), and 6A (gravel beaches)
• Wetlands, mangroves, etc.: Includes grasslands, scrublands/shrublands, and marshes. ESI categories 8D (vegetated, steeply sloping bluffs), 9B (vegetated low banks), 10A (salt- and brackish-water marshes, 10B (freshwater marshes), 10C (swamps), and 10D (scrub–shrub wetlands)
• Armored: ESI categories 1B (exposed, solid manmade structures, 6B (riprap), 8B (sheltered, solid manmade structures), and 8C (sheltered riprap)

After the regional shoreline was characterized, tables were generated detailing the length of each shoreline segment and its associated ESI type. These data were input into a series of computer programs to sum the total shoreline length and that of each of the shoreline types. ESI shoreline data are quite complex, however, in that a single shoreline segment may contain up to three ESI classifications. For example, a segment may have a tidal flat on the water side backed by a sand beach, then a marsh on the landward side. If a segment has different shoreline types, that segment is counted multiple times. However, when the total length of land/water interface is calculated, each shoreline segment is counted only once, regardless of the number of shoreline types it contains. Thus, the sum of the lengths of all the shoreline types will be greater than the total shoreline length. This double counting occurs for about 10% of the coastlines characterized.

Data Quality/Caveats: ESI shoreline coverage of the three regions shown was complete; the Pacific Northwest region also included considerable area along the shore of the Columbia River. Some of the older atlases used for this region were compiled more than 15 years ago. Though the West Coast is generally not considered an overly dynamic coastline, some changes may have altered coastline shape or type for a small percentage of this region.

Data Access: The data reported here are the result of an analysis undertaken specifically for this project; however, some data are available at http://response.restoration.noaa.gov/esi/esiintro.html.

The Data Gap

Data are not currently available for the majority of coastal regions; however, the necessary analyses are under way at NOAA.