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| USGS National Land Cover Database | |
|---|---|
| Name | National Land Cover Database |
| Caption | NLCD thematic land cover map |
| Established | 2001 |
| Agency | United States Geological Survey |
| Country | United States |
| Website | NLCD |
USGS National Land Cover Database The National Land Cover Database provides spatially explicit land cover and land cover change data for the United States. Developed by the United States Geological Survey in collaboration with the Multi-Resolution Land Characteristics Consortium and multiple federal, state, and academic partners, the database supports environmental monitoring, planning, and research. NLCD products integrate remote sensing, classification science, and geospatial analysis to produce standardized land cover maps, impervious surface estimates, and disturbance layers.
The NLCD is a national-scale mapping initiative managed by the United States Geological Survey and the Multi-Resolution Land Characteristics Consortium to produce consistent land cover products across the United States. NLCD outputs are used by agencies such as the Environmental Protection Agency, National Oceanic and Atmospheric Administration, Department of the Interior, and state departments like the California Department of Water Resources for policy, regulatory, and resource-management decisions. Research institutions including University of Maryland, University of Minnesota, Oregon State University, and University of Florida contribute methods and validation studies. International organizations such as the European Space Agency and agencies in Canada and Australia reference NLCD methods for national mapping efforts.
NLCD delivers multiple products: 30-meter resolution land cover classification, impervious surface rasters, land cover change products, and disturbance/change indicators. The hierarchical classification scheme ties to legacy systems and standards used by the National Vegetation Classification Standard and interoperable frameworks adopted by the Federal Geographic Data Committee. The NLCD thematic classes include categories such as deciduous forest, evergreen forest, mixed forest, shrubland, grassland, pasture/hay, cultivated crops, open water, wetlands, and developed classes subdivided by impervious surface. Product suites also include percent cultivated, percent tree canopy, and land-cover change mosaics used by agencies like the Bureau of Land Management and research centers at Yale University and Columbia University.
NLCD classification relies primarily on satellite remote sensing inputs from sensors such as the Landsat 5, Landsat 7, and Landsat 8 missions of the United States Geological Survey/National Aeronautics and Space Administration partnership, supplemented by ancillary data from the National Agricultural Statistics Service and high-resolution aerial imagery from state ortho programs. Analytical approaches include per-pixel supervised classification, decision-tree and random-forest algorithms developed in collaboration with groups at University of Wisconsin–Madison and Pennsylvania State University, and post-classification refinement using rule-based models informed by digital elevation models from the National Elevation Dataset and hydrography from the National Hydrography Dataset. Change detection methodologies use time-series compositing, spectral unmixing, and change-vector analysis validated against field plots and stratified sampling designs supported by USDA Forest Service inventories.
Since inception, NLCD has been released in major vintages (2001, 2006, 2011, 2016, 2019, and later updates), with interim products for imperviousness and percent tree canopy. Each version reflects sensor updates, algorithm refinements, and revised classification rules developed with partners including the National Aeronautics and Space Administration and state geospatial data offices. Historical comparisons have been used by studies at Harvard University, Stanford University, and University of Michigan to examine urbanization, forest change, and wetland loss over multi-decadal periods.
NLCD supports applications across federal programs and academic research: habitat modeling for the U.S. Fish and Wildlife Service and National Park Service; watershed and water-quality modeling used by the Environmental Protection Agency and state environmental agencies; urban-growth analyses for metropolitan planning organizations such as the Metropolitan Transportation Commission and the Chicago Metropolitan Agency for Planning; carbon accounting studies by the Intergovernmental Panel on Climate Change contributors; and disaster-response mapping coordinated with the Federal Emergency Management Agency. Universities and NGOs like The Nature Conservancy use NLCD for conservation prioritization, species-distribution models, and landscape fragmentation metrics.
NLCD accuracy assessments employ independent reference samples and error matrices following standards from the Federal Geographic Data Committee and statistical methods used at institutions like North Carolina State University and Michigan State University. Reported thematic accuracies vary by class and region; common commission and omission errors occur in heterogeneous landscapes, transitional shrub–grass mosaics, and cropland-forest interfaces. Limitations include the 30-meter spatial resolution that may miss fine-grained land use features, classification confusion in spectrally similar classes (e.g., harvested forest vs. shrubland), and temporal latency between land-change events and dataset release. Users needing higher spatial or temporal fidelity often integrate NLCD with commercial imagery from providers such as Planet Labs or high-resolution products from the National Agriculture Imagery Program.
NLCD data are distributed openly through the United States Geological Survey's data portals and are accessible via web services, bulk downloads, and APIs used by platforms like Esri, Google Earth Engine, and scientific computing environments at National Center for Atmospheric Research. Processing and analysis tools include NLCD-specific Python and R packages maintained by academic groups, web viewers provided by the USGS Earth Resources Observation and Science Center, and integration toolsets in geospatial desktop software used by state GIS offices and consulting firms.
Category:United States Geological Survey Category:Geographic information systems