The Coastal Change Analysis Program: Mapping change and monitoring change trends in the coastal zone

National Oceanic and Atmospheric Administration's Coastal-Change Analysis Program (C-CAP) develops land cover data for the coastal zone of the U.S. An immediate objective for C-CAP is to expeditiously complete a national standard of land cover and land cover change data, to which additional eras of imagery will be used to track coastal changes through time. This paper highlights techniques for mapping and interpreting multiple eras of land cover within a study area. Recent era Landsat Enhanced Thematic Mapper and retrospective Landsat Multi Spectral Scanner imagery were analyzed in conjunction with the existing C-CAP land cover and corresponding Landsat Thematic Mapper imagery. Spectral differencing change analysis techniques identified areas that have changed from era to era. Spectral clustering for each era of Landsat imagery derived land cover labels for the areas of change. The change areas were then applied to the C-CAP land cover maps to produce a full land cover product for each era in the study. Trends highlighted in this study were related to increased development within existing urban boundaries, the spread of residential development in the suburbs, and loss of forest cover in rural areas. The data sources, interpretation techniques, and change analysis methodology described in this paper could be employed to produce land cover, and trend data products in most regions that have existing land cover data, and is envisioned as a component of a continued C-CAP land cover change and trend mapping strategy.