U.S. Geological Survey
20200213
National Land Cover Database (NLCD) 2011 Land Cover - Alaska (ver. 2.0, July 2020)
20200724
remote-sensing image
Sioux Falls
U.S. Geological Survey
References: (1) Jin, S., Yang, L., Danielson, P., Homer, C., Fry, J., and Xian, G. 2013. A comprehensive change detection method for updating the National Land Cover Database to circa 2011. Remote Sensing of Environment, 132: 159 – 175. (2) Xian, G., Homer, C., Dewitz, J., Fry, J., Hossain, N., and Wickham, J., 2011. The change of impervious surface area between 2001 and 2006 in the conterminous United States. Photogrammetric Engineering and Remote Sensing, Vol. 77(8): 758-762. (3) Coulston, J. W., Moisen, G. G., Wilson, B. T., Finco, M. V., Cohen, W. B., and Brewer, C. K. 2012. Modeling percent tree canopy cover: a pilot study. Photogrammetric Engineering & Remote Sensing 78(7): 715-727. (4) Jin, Suming, Yang, Limin, Zhu, Zhe, Homer, Collin G., A land cover change detection and classification protocol for updating Alaska NLCD 2001 to 2011: Remote Sensing of Environment, v. 195, p. 44–55, at https://doi.org/10.1016/j.rse.2017.04.021. (5) Selkowitz, D. J., Stehman, S. V., Thematic accuracy of the National Land Cover Database (NLCD) 2001 land cover for Alaska: Remote Sensing of Environment, v. 115, no. 6, p. 1401–1407, at https://doi.org/10.1016/j.rse.2011.01.020. The USGS acknowledges the support of USGS and contractor NLCD 2016 Land Cover Mapping Teams in development of data for this map.
https://doi.org/10.5066/P96HHBIE
http://www.mrlc.gov
This update to the Alaska National Land Cover Database (NLCD) 2016 replaces the files dated 20200213. In this update the landcover footprint was extended along the northern coast to include the islands that were missed in previous versions, and several duplicate roads (offset by 1 or 2 pixels) were removed on the Aleutian Islands. The Alaska National Land Cover Database 2016 was created using change detection between the nominal dates of 2011 and 2016 utilizing Google Earth engine composites of Landsat imagery. Traditionally, previous classifications of Alaska used path row data and spectral comparisons between path rows along with ancillary data to derive areas of change. Alaska has many challenges for land cover classification, with the largest of these being a very short “leaf on” imagery season for acceptable phenology. This is compounded by persistent cloud cover during this growing season, and increasing terrain shadow and sun angle problems outside of this season. For this reason, the timeframe of 10 years was needed for the first update to the Alaska land cover in order to have enough acceptable imagery between these 2001 and 2011 nominal dates that met these criteria in order to provide reasonable change detection. For 2016, there was not enough complete path row imagery to do this similar change detection. Google Earth engine was employed to create a composite imagery mosaic that uses much smaller pieces of Landsat imagery to create a complete Landsat imagery snapshot used to create change detection between 2011 and 2016. Although this composite technique is not as scientifically rigorous as utilizing direct Landsat imagery, it was the only method available to us during production that would allow completion of change detection in the desired five year timeframe.
The original published 2001 and 2011 Alaska NLCD classifications are generally unchanged, except for slight updates in the northern part of the state to remove perennial ice and snow that were a result of lack of suitable imagery in the 2001 timeframe representing minimum snow and ice extent. See the 2001 and 2011 Land Cover products for the specific metadata process steps associated with the creation of those datasets.
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.
Corner Coordinates (projection meters)
Upper Left Corner: -2232330(X), 2380110(Y)
Lower Right Corner: 1494720(X), 344820(Y)
19980607
20140901
ground condition
As needed
Land Cover Alaska
-167.0000
-122.0000
77.0000
40.0000
ISO 19115 Topic Category
imageryBaseMapsEarthCover
NGDA Portfolio Themes
NGDA
National Geospatial Data Asset
Land Use Land Cover Theme
None
Land Cover
GIS
U.S. Geological Survey
USGS
digital spatial data
U.S. Department of Commerce, 1995, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions, Federal Information Processing Standard 10-4,): Washington, D.C., National Institute of Standards and Technology
United States
U.S.
US
U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, D.C., National Institute of Standards and Technology
AK
Alaska
None. Please see 'Distribution Info' for details.
None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.
Customer Services Representative
U.S. Geological Survey
mailing and physical
47914 252nd Street
Sioux Falls
SD
57198-0001
United States
605/594-6151
605/594-6589
custserv@usgs.gov
U.S. Geological Survey
Microsoft Windows 7 Version 6.1 (Build 7601: Service Pack 1); ESRI ArcCatalog 9.3.1.4000 (Service Pack 2)
A formal accuracy assessment was completed for the original 2001 Land Cover product (citation 5). Change pixels were derived for the 2011 and 2016 Land Cover products based on specific criteria. An accuracy assessment has not been conducted for those change pixels. See the process steps in the metadata of the 2011 and 2016 Land Cover products for more information about the creation of those datasets.
This document and the described land cover map are considered "provisional" until a formal accuracy assessment is completed. The U.S. Geological Survey can make no guarantee as to the accuracy or completeness of this information, and it is provided with the understanding that it is not guaranteed to be correct or complete. Conclusions drawn from this information are the responsibility of the user.
Manual and automated QA/QC checks on the NLCD 2001 Land Cover Alaska dataset verified the positional accuracy of the pixel grid and confirmed that all thematic attributes belonged to one of the approved NLCD classes.
This 2011 NLCD product of Alaska Land Cover layer is the version dated July 24, 2020.
N/A
N/A
Collin Homer
Jon Dewitz
Limin Yang
201505
Completion of the 2011 National Land Cover Database for the Conterminous United States - Representing a Decade of Land Cover Change Information
publication
https://www.researchgate.net/publication/282254893_Completion_of_the_2011_National_Land_Cover_Database_for_the_Conterminous_United_States_-_Representing_a_Decade_of_Land_Cover_Change_Information
Digital and/or Hardcopy
201505
publication date
Landsat ETM
Landsat Enhanced Thematic Mapper (ETM)
Collin Homer
Jon Dewitz
Limin Yang
201505
Completion of the 2011 National Land Cover Database for the Conterminous United States - Representing a Decade of Land Cover Change Information
publication
https://www.researchgate.net/publication/282254893_Completion_of_the_2011_National_Land_Cover_Database_for_the_Conterminous_United_States_-_Representing_a_Decade_of_Land_Cover_Change_Information
Digital and/or Hardcopy
201505
publication date
USDA
United States Department of Agriculture (USDA)
USDA Forest Service
20181102
Forest Inventory & Analysis: What is Forest Inventory and Analysis?
publication
What_is_FIA_FS_2018_update.pdf
https://www.fia.fs.fed.us/
Digital and/or Hardcopy
20181102
publication date
FIA
Forest Inventory and Analysis (FIA) Program of the U.S. Forest Service
Collin Homer
Jon Dewitz
Limin Yang
201505
Completion of the 2011 National Land Cover Database for the Conterminous United States - Representing a Decade of Land Cover Change Information
publication
https://www.researchgate.net/publication/282254893_Completion_of_the_2011_National_Land_Cover_Database_for_the_Conterminous_United_States_-_Representing_a_Decade_of_Land_Cover_Change_Information
Digital and/or Hardcopy
201505
publication date
DEM
Digital Elevation Model (DEM)
Collin Homer
Jon Dewitz
Limin Yang
201505
Completion of the 2011 National Land Cover Database for the Conterminous United States - Representing a Decade of Land Cover Change Information
publication
https://www.researchgate.net/publication/282254893_Completion_of_the_2011_National_Land_Cover_Database_for_the_Conterminous_United_States_-_Representing_a_Decade_of_Land_Cover_Change_Information
Digital and/or Hardcopy
201505
publication date
USGS/EROS
United States Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center
Collin Homer
Jon Dewitz
Limin Yang
201505
Completion of the 2011 National Land Cover Database for the Conterminous United States - Representing a Decade of Land Cover Change Information
publication
https://www.researchgate.net/publication/282254893_Completion_of_the_2011_National_Land_Cover_Database_for_the_Conterminous_United_States_-_Representing_a_Decade_of_Land_Cover_Change_Information
Digital and/or Hardcopy
201505
publication date
USGS NLCD
United States Geological Survey (USGS) National Land Cover Database (NLCD)
A custom method was developed to update Alaska NLCD from 2001 to 2011. The method was designed to capitalize on available ancillary data and to capture the main land change drivers including: - Fire disturbance and succession, - Forest clearing and harvesting, - Glacier and snow/ice changes, and - Urban change. We began imagery selection by focusing on odd-numbered Landsat paths. We selected as many leaf-on, cloud-free (or few clouds), same-date images in a path as possible, and mosaicked those to create larger mapping units. Final mapping units were composed of one to four Landsat images. For the Aleutians and other islands, cloud-free images were virtually nonexistent, so those areas were not mapped using image processing and models. Instead, they were visually checked for change from the 2001 land cover map using any available Landsat images and Google Earth. For the mainland area of Alaska we created 44 mapping units and used 22 additional Landsat scenes for the visual inspections of the islands. Once mapping units were identified, the “base” images were cloud-masked. “Reference” scenes from different dates were used in a model to fill in the masked areas of the base scenes. Once the base scenes were cloud-filled, they were mosaicked to form each full mapping unit. Tasseled cap, normalized burn ratio (NBR), normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) images were calculated for each mapping unit. Ancillary data included: - Digital elevation model (DEM) and derivatives (slope and aspect), - Fire and forest thinning polygons obtained from the state of Alaska, Landfire, and the Monitoring Trends in Burn Severity (MTBS) project, - Moderate Resolution Imaging Spectroradiometer (MODIS) snow/ice raster data, and - 2001 NLCD. Change detection and classification models used NLCD 2001 and ancillary data to predict land cover classes for changed areas. An example of the logic is as follows: If (NLCD 2001 is forest & wildfire occurred less than 4 years ago & dNBR is high & NBR 2011 is low), then it is likely the new land cover type is herbaceous in 2011. The general modeling process was as follows: 1. Biomass increase was calculated from spectral and DEM derivatives, plus 2001 land cover. 2. Biomass increase was added to the disturbance data, yielding a disturbance template. 3. The disturbance template plus the spectral derivatives (NBR, NDVI) were compared to the 2001 land cover to model updated vegetation change areas. 4. The updated vegetation change areas were inserted into the 2001 land cover to create training data for a classification and regression tree (CART) model. 5. A CART classification was used to detect unmapped disturbances and change. 6. The vegetation classification was refined to detect and correct for areas of shadow and succession after forest fires, clearing or thinning. 7. Snow/ice change was detected using an algorithm based on NDWI for 2001 and 2011 plus topography (correction for shadows) and MODIS snow/ice data, which yielded snow/ice change areas. 8. Water change was detected using a Landsat-based water change detection algorithm, refined by land cover and topography data (shadow areas) to detect changes. 9. The vegetation, snow/ice, and water change areas were combined to update the overall classification and to derive a set of change pixels. 10. Change pixels in urban/developed areas were created by modeling change in major cities. Manual editing was used to add developed change for small towns and other features. After all mapping units were processed, the change pixels were mosaicked and checked for consistency and quality. Manual edits were used to clean up areas that were incorrectly classified. Snow, ice, and water extents were mapped directly from Landsat imagery. As a result, the extent of snow, ice, and water reflects the year and season when the imagery was recorded. Differences in snow, ice, and water extent between 2001 and 2011 may not reflect perennial changes in their extent, but simply reflect seasonal change between the two time periods.
Landsat ETM
USDA
FIA
DEM
USGS/EROS
20200724
USGS NLCD
Customer Services Representative
U.S. Geological Survey
mailing address
47914 252nd Street
Sioux Falls
SD
57198-0001
United States
605/594-6151
605/594-6589
custserv@usgs.gov
Raster
Pixel
67844
124236
1
Albers Conical Equal Area
55.000000
65.000000
-154.000000
50.000000
0.000000
0.000000
coordinate pair
30.000000
30.000000
meters
World Geodetic System 1984 (WGS 84)
WGS_1984
6378137.000000
298.257222
None
NLCD Land Cover Layer
National Land Cover Database 2016
ObjectID
Internal feature number
ESRI
Sequential unique whole numbers that are automatically generated
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
NLCD
Integer
ValueLand Cover Class Code Value: Land cover defines the material on the land’s surface. The categories, or classes, used by the NLCD are from a modified Anderson Land Cover Classification SystemNLCD
0
Background/No Data
NLCD land cover class descriptions
1
No data value, Alaska zones only
NLCD land cover class descriptions
11
Open Water - All areas of open water, generally with less than 25% cover or vegetation or soil
NLCD 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 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 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 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 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 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 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 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 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 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 tundra and may be periodically or seasonally wet and/or saturated with wate. This type commonly occurs in alpine or tundra areas and may contain permafrost
NLCD 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 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 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 and may be periodically or seasonally wet and/or saturated. This type may contain permafrost
NLCD land cover class descriptions
74
Moss- Alaska only areas dominated by mosses generally greater than 80% of total vegetation
NLCD 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 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 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 persistently saturated with or covered with water
NLCD 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 persistently saturated with or covered with water
NLCD land cover class descriptions
Red
Numeric code for Red color in RGB slice format for image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user
NLCD
0
100
CSS Color Value Percentage
0.1
Green
Numeric code for Green color in RGB slice format for image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user
NLCD
0
100
CSS Color Value Percentage
0.1
Blue
Numeric code for Blue color in RGB slice format for image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user
NLCD
0
100
CSS Color Value Percentage
0.1
Opacity
A measure of how opaque, or solid, a color is displayed in a layer
NLCD
0
100
percentage
0.1
Attributes defined by USGS and ESRI. Class Red Green Blue 0 0.000000000 0.000000000 0.000000000 1 0.000000000 1.000000000 0.000000000 11 0.325490196 0.462745098 0.662745098 12 0.854901961 0.913725490 1.000000000 21 0.913725490 0.819607843 0.815686275 22 0.890196078 0.615686275 0.545098039 23 0.976470588 0.000000000 0.000000000 24 0.705882353 0.000000000 0.000000000 31 0.741176471 0.725490196 0.670588235 41 0.443137255 0.701960784 0.419607843 42 0.137254902 0.423529412 0.231372549 43 0.752941176 0.827450980 0.607843137 51 0.694117647 0.588235294 0.235294118 52 0.835294118 0.764705882 0.533333333 71 0.925490196 0.925490196 0.796078431 72 0.823529412 0.823529412 0.505882353 74 0.513725490 0.725490196 0.619607843 81 0.901960784 0.882352941 0.282352941 82 0.709803922 0.486274510 0.200000000 90 0.760784314 0.878431373 0.949019608 95 0.486274510 0.674509804 0.772549020
Attribute accuracy is described, where present, with each attribute defined in the Entity and Attribute Section
GS ScienceBase
U.S. Geological Survey
mailing address
Denver Federal Center, Building 810, Mail Stop 302
Denver
CO
80225
United States
1-888-275-8747
sciencebase@usgs.gov
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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
Digital Data
https://doi.org/10.5066/P96HHBIE
None
20200924
Customer Services Representative
U.S. Geological Survey
mailing and physical
47914 252nd Street
Sioux Falls
SD
57198-0001
United States
605/594-6151
605/594-6589
custserv@usgs.gov
FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata
FGDC-STD-001.1-1999