United States national land cover data base development 1992–2001 and beyond

An accurate, up-to-date and spatially-explicate national land cover database is required for monitoring the status and trends of the nationpsilas terrestrial ecosystem, and for managing and conserving land resources at the national scale. With all the challenges and resources required to develop such a database, an innovative and scientifically sound planning must be in place and a partnership be formed among users from government agencies, research institutes and private sectors. In this paper, we summarize major scientific and technical issues regarding the development of the NLCD 1992 and 2001. Experiences and lessons learned from the project are documented with regard to project design, technical approaches, accuracy assessment strategy, and project implementation. Future improvements in developing next generation NLCD beyond 2001 are suggested, including: (1) enhanced satellite data preprocessing in correction of atmospheric and adjacency effect and the topographic normalization; (2) improved classification accuracy through comprehensive and consistent training data and new algorithm development; (3) multi-resolution and multitemporal database targeting major land cover changes and land cover database updates; (4) enriched database contents by including additional biophysical parameters and/or more detailed land cover classes through synergizing multi-sensor, multi-temporal, and multi-spectral satellite data and ancillary data, and (5) transform the NLCD project into a national land cover monitoring program.