| Section 1 | Overview | |||
| Originator | U.S. Geological Survey | |||
| Title | National Land Cover Database (NLCD) 2021 Land Cover Conterminous United States | |||
| Abstract | The U.S. Geological Survey (USGS), in partnership with several federal agencies, has now developed and released seven National Land Cover Database (NLCD) products: NLCD 1992, 2001, 2006, 2011, 2016, 2019, and 2021. Beginning with the 2016 release, land cover products were created for two-to-three-year intervals between 2001 and the most recent year. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. NLCD continues to provide innovative, consistent, and robust methodologies for production of a multi-temporal land cover and land cover change database. NLCD 2021 adds an additional year to the map products produced for NLCD 2019, with a streamlined compositing process for assembling and preprocessing Landsat imagery and geospatial ancillary datasets; a temporally, spectrally, and spatially integrated land cover change analysis strategy; a theme-based post-classification protocol for generating land cover and change products; a continuous fields biophysical parameters modeling method; and a scripted operational system. The overall accuracy of the 2019 Level I land cover was 91%. Results from this study confirm the robustness of this comprehensive and highly automated procedure for NLCD 2021 operational mapping (see https://doi.org/10.1080/15481603.2023.2181143 | |||
| Purpose | The goal of this project is to provide the Nation with complete, current, and consistent public domain information on its land use and land cover. | |||
| Time Period of Content Date | ||||
| Currentness Reference | ground condition | |||
| Progress | In work | |||
| Maintenance and Update Frequency | Every 2-3 years | |||
| Spatial Extent of Data | Corner Coordinates (center of pixel, projection meters) Upper Left Corner: -2493045 meters(X), 3310005 meters(Y) Lower Right Corner: 2342655 meters(X), 177285 meters(Y) | |||
| Bounding Coordinates | -130.2328 -63.6722 52.8510 21.7423 | |||
| Place Keywords | United States | |||
| Theme Keywords | imageryBaseMapsEarthCover | |||
| Theme Keyword Thesaurus | ISO 19115 Topic Category | |||
| Access Constraints | None. Please see 'Distribution Info' for details. | |||
| Use Constraints | None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. | |||
| Contact Person Information | ,
Customer Service Representative 47914 252nd Street Sioux Falls, SD 57198-0001 Phone: (605) 594-6151 Email: custserv@usgs.gov | |||
| Browse Graphic | None available | |||
| Associated Data Sets | Overall Methodology Design for the United States National Land Cover Database 2016 Products | |||
| Section 2 | Data Quality | |||
| Attribute Accuracy | A formal accuracy assessment has not been conducted for NLCD 2021 Land Cover, NLCD 2021 Land Cover Change, or NLCD 2021 Impervious Surface products. A 2019 accuracy assessment publication can be found here: James Wickham, Stephen V. Stehman, Daniel G. Sorenson, Leila Gass & Jon A. Dewitz (2023) Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States, GIScience & Remote Sensing, 60:1, DOI: 10.1080/15481603.2023.2181143. | |||
| Logical Consistency | See https://www.mrlc.gov/data | |||
| Completeness | This NLCD product is the version dated June 30, 2023. | |||
| Horizontal Positional Accuracy | N/A | |||
| Vertical Positional Accuracy | N/A | |||
| Lineage | Landsat imagery processing - The National Land Cover Database (NLCD) is fundamentally based on the analysis of Landsat data. Beginning with NLCD 2019, we used composite images rather than individual Landsat scenes. Compositing made imagery generation more automated, reduced latency, and increased the mapping extent. Also, as of NLCD 2019, we divided CONUS into 50 blocks, each containing approximately 9 path/rows. For NLCD 2021 we also used synthetic Landsat imagery. | |||
| Section 3 | Spatial Data Organization (not used in this metadata) | |||
| Section 4 | Coordinate System | |||
| Horizontal Coordinate Scheme | ||||
| Horizontal Datum | WGS_1984 | |||
| Horizontal Units | meters | |||
| Cell Width | 30.0 | |||
| Cell Height | 30.0 | |||
| Section 5 | Attributes | |||
| Overview | Land Cover Class RGB Color Value Table. The specific RGB values for the NLCD Land Cover Class's that were used for NLCD 2021. | |||
| Detailed Citation | Attributes defined by USGS and ESRI. Value Red Green Blue 0 0 0 0 11 70 107 159 12 209 222 248 21 222 197 197 22 217 146 130 23 235 0 0 24 171 0 0 31 179 172 159 41 104 171 95 42 28 95 44 43 181 197 143 52 204 184 121 71 223 223 194 81 220 217 57 82 171 108 40 90 184 217 235 95 108 159 184 | |||
| Table Detail: | ||||
| NLCD Land Cover Layer Attribute Table - Land Cover class counts and descriptions for the NLCD Land Cover Database (National Land Cover Database) | |||
| Field Name | Valid Values | Definition | Definition Source |
|---|---|---|---|
| OID | Internal feature number. | ESRI | |
| Count | A nominal integer value that designates the number of pixels that have each value in the file; histogram column in ERDAS Imagine raster attributes table. | ESRI | |
| NLCD Land Cover Class | enumerated | Land Cover Class Code Value. | NLCD Legend Land Cover Class Descriptions |
| 0 | Unclassified | Producer defined | |
| 11 | Open Water - All areas of open water, generally with less than 25% cover or vegetation or soil. | NLCD Legend Land Cover Class Descriptions | |
| 12 | Perennial Ice/Snow - All areas characterized by a perennial cover of ice and/or snow, generally greater than 25% of total cover. | NLCD Legend Land Cover Class Descriptions | |
| 21 | Developed, Open Space - Includes areas with a mixture of some constructed materials, but mostly vegetation in the form of lawn grasses. Impervious surfaces account for less than 20 percent of total cover. These areas most commonly include large-lot single-family housing units, parks, golf courses, and vegetation planted in developed settings for recreation, erosion control, or aesthetic purposes. | NLCD Legend Land Cover Class Descriptions | |
| 22 | Developed, Low Intensity -Includes areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 20-49 percent of total cover. These areas most commonly include single-family housing units. | NLCD Legend Land Cover Class Descriptions | |
| 23 | Developed, Medium Intensity - Includes areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 50-79 percent of the total cover. These areas most commonly include single-family housing units. | NLCD Legend Land Cover Class Descriptions | |
| 24 | Developed, High Intensity - Includes highly developed areas where people reside or work in high numbers. Examples include apartment complexes, row houses and commercial/industrial. Impervious surfaces account for 80 to 100 percent of the total cover. | NLCD Legend Land Cover Class Descriptions | |
| 31 | Barren Land (Rock/Sand/Clay) - Barren areas of bedrock, desert pavement, scarps, talus, slides, volcanic material, glacial debris, sand dunes, strip mines, gravel pits and other accumulations of earthen material. Generally, vegetation accounts for less than 15% of total cover. | NLCD Legend Land Cover Class Descriptions | |
| 41 | Deciduous Forest - Areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. More than 75 percent of the tree species shed foliage simultaneously in response to seasonal change. | NLCD Legend Land Cover Class Descriptions | |
| 42 | Evergreen Forest - Areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. More than 75 percent of the tree species maintain their leaves all year. Canopy is never without green foliage. | NLCD Legend Land Cover Class Descriptions | |
| 43 | Mixed Forest - Areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. Neither deciduous nor evergreen species are greater than 75 percent of total tree cover. | NLCD Legend Land Cover Class Descriptions | |
| 51 | Dwarf Scrub - Alaska only areas dominated by shrubs less than 20 centimeters tall with shrub canopy typically greater than 20% of total vegetation. This type is often co-associated with grasses, sedges, herbs, and non-vascular vegetation. | NLCD Legend Land Cover Class Descriptions | |
| 52 | Shrub/Scrub - Areas dominated by shrubs; less than 5 meters tall with shrub canopy typically greater than 20% of total vegetation. This class includes true shrubs, young trees in an early successional stage or trees stunted from environmental conditions. | NLCD Legend Land Cover Class Descriptions | |
| 71 | Grassland/Herbaceous - Areas dominated by grammanoid or herbaceous vegetation, generally greater than 80% of total vegetation. These areas are not subject to intensive management such as tilling, but can be utilized for grazing. | NLCD Legend Land Cover Class Descriptions | |
| 72 | Sedge/Herbaceous - Alaska only areas dominated by sedges and forbs, generally greater than 80% of total vegetation. This type can occur with significant other grasses or other grass like plants, and includes sedge tundra, and sedge tussock tundra. | NLCD Legend Land Cover Class Descriptions | |
| 73 | Lichens - Alaska only areas dominated by fruticose or foliose lichens generally greater than 80% of total vegetation. | NLCD Legend Land Cover Class Descriptions | |
| 74 | Moss - Alaska only areas dominated by mosses, generally greater than 80% of total vegetation. | NLCD Legend Land Cover Class Descriptions | |
| 81 | Pasture/Hay - Areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the production of seed or hay crops, typically on a perennial cycle. Pasture/hay vegetation accounts for greater than 20 percent of total vegetation. | NLCD Legend Land Cover Class Descriptions | |
| 82 | Cultivated Crops - Areas used for the production of annual crops, such as corn, soybeans, vegetables, tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation accounts for greater than 20 percent of total vegetation. This class also includes all land being actively tilled. | NLCD Legend Land Cover Class Descriptions | |
| 90 | Woody Wetlands - Areas where forest or shrub land vegetation accounts for greater than 20 percent of vegetative cover and the soil or substrate is periodically saturated with or covered with water. | NLCD Legend Land Cover Class Descriptions | |
| 95 | Emergent Herbaceous Wetlands - Areas where perennial herbaceous vegetation accounts for greater than 80 percent of vegetative cover and the soil or substrate is periodically saturated with or covered with water. | NLCD Legend Land Cover Class Descriptions | |
| Red | 0 to 255 | Red color code for RGB. The value is arbitrarily assigned by the display software package, unless defined by user. | NLCD 2021 |
| Green | 0 to 255 | Green color code for RGB. The value is arbitrarily assigned by the display software package, unless defined by user. | NLCD 2021 |
| Blue | 0 to 255 | Blue color code for RGB. The value is arbitrarily assigned by the display software package, unless defined by user. | NLCD 2021 |
| Opacity | 0 to 0.1 | A measure of how opaque, or solid, a color is displayed in a layer. | NLCD 2021 |
| Value | enumerated | *while the file structure shows values in range from 0-255, the values of 0-100 are the only real populated values, in addition to a background value of 127. | NLCD 2021 |
| 127 | Background value | Producer defined | |
| Section 6 | Distribution | |||
| Publisher | U.S. Geological Survey | |||
| Publication Date | 06/30/2023 | |||
| Contact Person Information | ,
Denver Federal Center, Building 810, Mail Stop 302 Denver, CO 80225 Phone: 1-888-275-8747 Email: sciencebase@usgs.gov | |||
| Distributor's Data Set Identifier | ||||
| Distribution Liability | Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. | |||
| Ordering Instructions | ||||
| Online Linkage | I AGREE to the notice in "Distribution Liability" above. Clicking to agree will either begin the download process, link to a service, or provide more instructions. See "Ordering Instructions" above for details. | |||
| Section 7 | Metadata Reference | |||
| Metadata Date | 07/11/2023 | |||
| Contact Person Information | ,
Customer Service Representative 47914 252nd Street Sioux Falls, SD 57198-0001 Phone: (605) 594-6151 Fax: 605/594-6589 Email: custserv@usgs.gov | |||
| Metadata Standard Name | FGDC Content Standard for Digital Geospatial Metadata | |||
| Metadata Standard Version | FGDC-STD-001-1998 | |||
| Metadata Standard Online Linkage | ||||