Source: Jan Nelson, Collin Homer, Jon Campbell, USGS
The latest edition of the National Land Cover Database (NLCD 2006) is now publicly available. This massive database updates our knowledge of the Nation’s land cover and documents precisely where land cover change has occurred between 2001 and 2006. NLCD is used for thousands of applications in such diverse investigations as ecosystem status and health, spatial patterns of biodiversity, indications of climate change, and best practices in land management.
“Periodic updating of the NLCD can be compared to taking a new census of the state of our land cover,” said U.S. Geological Survey (USGS) Director Marcia McNutt. “Just as repeating the census reveals demographic trends that provide a wealth of information for social science research, monitoring land cover change can similarly serve many purposes in natural science and land management.”
Based on Landsat satellite imagery taken in 2006, the broad, yet meticulous database was constructed in a five-year collaborative effort by the 11-member federal interagency Multi-Resolution Land Characteristics Consortium (MRLC).
“The long-term collaboration that the MRLC demonstrates is a model of cooperation among government entities,” Director McNutt continued. “Their teamwork in producing the multi-purpose NLCD helps accelerate science and it saves taxpayer money. That’s a synergy everyone can applaud.”
The carefully calibrated data describes the land surface condition of each 30-meter cell of land in the conterminous United States and identifies which ones have changed since the year 2001. Nearly six such cells—each 98 feet long and wide—would fit on a football field. This release of NLCD marks the first time land cover change has been captured for the Nation in such a detailed way, requiring several years of new methodological research to accomplish this goal.
The range and authoritative accuracy of this information will enable managers of public and private lands, urban planners, agricultural experts, and scientists with many different interests (for instance, invasive species or hydrogeography) to identify critical characteristics of the land and patterns of land cover change, informing a variety of investigations from monitoring forests to modeling runoff in urban areas.
Land cover is broadly defined as the biophysical pattern of natural vegetation, agriculture, and urban areas. It is shaped by both natural processes and human influences. NLCD 2006 data portrays 16 classes of land cover in the lower 48 states and the degree of surface imperviousness in urban areas. The density of non-transpiring, impervious surfaces—usually composed of concrete, asphalt, stone, and metal—is widely recognized as a key indicator of environmental quality in urban areas.
For more information and to download NLCD data, visit the National Land Cover Database website.
+ USGS Press Release
+ NLCD Website