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This statewide dataset contains a combination of land cover mapping from 2016 aerial imagery and land use derived from standardized assessor parcel information for Massachusetts.
Each location in this layer is associated with a land cover class value as well as a parcel use code
Although both land cover and land use information are included, each of these aspects can be accessed independently, or in interesting and useful combinations with one another. For instance, a user can simply display impervious surfaces (land cover), or commercial parcels (land use). In combination, it is possible to display and measure the portions of the commercial parcels that are covered by impervious surfaces or the portions of residential parcels used as developed open space.
This layer is the result of a cooperative project between MassGIS and the National Oceanic and Atmospheric Administration’s (NOAA) Office of Coastal Management (OCM). Funding was provided by the Mass. Executive Office of Energy and Environmental Affairs.
MassGIS stores the data as a single statewide polygon feature class named LANDCOVER_LANDUSE_POLYin the spatial reference of NAD_1983_Contiguous_USA_Albers (EPSG: 5070).
Data development
The following sections describe the development and features of the two components, land cover and land use, as well as the final combined dataset.
Land cover
The thematic land cover dataset was created in raster format by NOAA's Coastal Change Analysis Program (C-CAP). C-CAP has produced numerous standardized land cover products which are included in the National Land Cover Database. These products are used in numerous ways to assess urban growth, inventory wetlands, coastal intertidal areas, and adjacent uplands, and delineate wildlife habitat to monitor changes in these areas. This information helps in the understanding of the landscape's response to natural and human-caused changes. OCM worked in close coordination with MassGIS to produce the land cover. OCM delivered the data to MassGIS in an Albers projection.
2016 NAIP imagery This 2016 land cover information was initially developed as a 1-meter, 6-category draft raster derived from 2016 USDA National Agricultural Imagery Program (NAIP) aerial multispectral imagery. Classes were impervious, bare, grass, shrub, tree, and water. Additional reference data were used to create this 19-class version, including: 2016 WorldView multispectral satellite imagery, lidar-based terrain elevation data, 2016-era 2D structures data, and other ancillary data such as MassDOT Roads, MassDEP Wetlands, etc. The wetlands in the final land cover product are exclusively from the C-CAP program and will differ from the MassDEP Wetlands data.
The land cover information in this product is consistent with C-CAP’s High-Resolution Land Cover Classification Scheme (PDF). Also see General information about C-CAP High-Resolution Land Cover.
Land use
The land use component of the data layer is represented by the Property Type Classification Code associated with each parcel in MassGIS' Standardized "Level 3" Parcels layer. These "use codes" come from the Mass. Department of Revenue Division of Local Services (DLS), along with custom use codes some municipalities include in their parcel data.
For this project, MassGIS created a parcel layer using data deliverables as close as possible to the time of the 2016 NAIP imagery used for the land cover. Since parcel data complying with Level 3 of the MassGIS standard was not available from every municipality for the year 2016, some information was selected from a different year to use data as close to 2016 as possible, with the following rules:
If Fiscal Year (FY) 2016 data was available, it was used. Otherwise, data was used from other years in the following order: 2017 (+1), 2015 (-1), 2018 (+2), 2014 (-2), 2013 (-3), 2012 (-4), 2011 (-5). Fiscal year values were retained in the final product to help indicate relative reliability of the USECODE.
MassGIS merged these parcel data into one feature class and dissolved them based on these fields:
USE_CODE: Use code from DOR DLS, along with custom use codes some municipalities include in their parcel data.
FY: Fiscal year
POLY_TYPE: Parcel type (FEE, TAX, ROW, WATER, PRIV_ROW, RAIL_ROW)
TOWN_ID: Town ID (1-351)
GEN_CODE: Generalized use code chosen by MassGIS for this project to simplify the 1,600+ USE_CODEs for map display.
Combined Land Cover – Land Use Data
For efficient processing and distribution, MassGIS split up the statewide land cover raster into 291 smaller, regularly sized and spaced tiles, each 10km by 10km (10,000 x 10,000 pixels).
The Create Fishnet tool produced a polygon index that precisely fit the tiles. The tiles were identified with a TILENAME value based on row and column position. For example, TILENAME “R07C17” identifies the tile in row 7, column 17. The index is named LANDCOVER_USE_INDEX_POLY. Aside from TILENAME, the other field is SHP_LINK, which stores a link to download a zipped land cover-land use shapefile for each tile.
Each land cover image was converted to a polygon shapefile using a Raster to Shapefile model in ERDAS IMAGINE. This method preserves the thematic attributes and simplifies the polygons very slightly.
MassGIS carried out the following steps in ArcGIS 10.6.1:
Reprojected the land use polygons from Massachusetts State Plane to the same Albers projection of the land cover.
Used the Identity tool to geometrically combine the land cover polygons with the dissolved parcel data to produce a land cover-land use feature class for each tile.
Checked and repaired the geometry of the Identity output.
Converted all multipart polygons to single-part polygons in the Identity output.
The Identity created numerous very small polygons because the two components (land cover and land use) were not spatially correlated. To preserve the input data, MassGIS decided not to eliminate polygons or perform any other cartographic refinement at this point. Users can easily perform these operations if desired.
As part of final QA, MassGIS modified the attributes of a small number of polygons with erroneous land cover or generalized land use codes, including a few right-of-way polygons in Boston that did not have the correct USEGENCODE of 55.