Area- and Depth-Weighted Averages of Selected SSURGO Variables for the Conterminous United States and District of Columbia

Dates

Release Date: 2014-07-10
Start Date: 2014-03-05
End Date: 2014-07-10
Publication Date: 2023-09-15

Citation

Wieczorek, M.E., 2014, Area- and Depth-Weighted Averages of Selected SSURGO Variables for the Conterminous United States and District of Columbia: U.S. Geological Survey data release, https://doi.org/10.5066/P92JJ6UJ.

Summary

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release. This digital data release consists of seven national data files of area- and depth-weighted averages of select soil attributes for every available county in the conterminous United States and the District of Columbia as of March 2014. The files are derived from Natural Resources Conservations Service’s (NRCS) Soil Survey Geographic database (SSURGO). The data files can be linked to the raster datasets of soil mapping unit identifiers (MUKEY) available [...]

Summary

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release.

This digital data release consists of seven national data files of area- and depth-weighted averages of select soil attributes for every available county in the conterminous United States and the District of Columbia as of March 2014. The files are derived from Natural Resources Conservations Service’s (NRCS) Soil Survey Geographic database (SSURGO). The data files can be linked to the raster datasets of soil mapping unit identifiers (MUKEY) available through the NRCS’s Gridded Soil Survey Geographic (gSSURGO) database (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628). The associated files, named DRAINAGECLASS, HYDRATING, HYDGRP, HYDRICCONDITION, LAYER, TEXT, and WTDEP are area- and depth-weighted average values for selected soil characteristics from the SSURGO database for the conterminous United States and the District of Columbia. The SSURGO tables were acquired from the NRCS on March 5, 2014. The soil characteristics in the DRAINAGE table are drainage class (DRNCLASS), which identifies the natural drainage conditions of the soil and refers to the frequency and duration of wet periods. The soil characteristics in the HYDRATING table are hydric rating (HYDRATE), a yes/no field that indicates whether or not a map unit component is classified as a "hydric soil". The soil characteristics in the HYDGRP table are the percentages for each hydrologic group per MUKEY. The soil characteristics in the HYDRICCONDITION table are hydric condition (HYDCON), which describes the natural condition of the soil component. The soil characteristics in the LAYER table are available water capacity (AVG_AWC), bulk density (AVG_BD), saturated hydraulic conductivity (AVG_KSAT), vertical saturated hydraulic conductivity (AVG_KV), soil erodibility factor (AVG_KFACT), porosity (AVG_POR), field capacity (AVG_FC), the soil fraction passing a number 4 sieve (AVG_NO4), the soil fraction passing a number 10 sieve (AVG_NO10), the soil fraction passing a number 200 sieve (AVG_NO200), and organic matter (AVG_OM). The soil characteristics in the TEXT table are percent sand, silt, and clay (AVG_SAND, AVG_SILT, and AVG_CLAY). The soil characteristics in the WTDEP table are the annual minimum water table depth (WTDEP_MIN), available water storage in the 0-25 cm soil horizon (AWS025), the minimum water table depth for the months April, May and June (WTDEPAMJ), the available water storage in the first 25 centimeters of the soil horizon (AWS25), the dominant drainage class (DRCLSD), the wettest drainage class (DRCLSWET), and the hydric classification (HYDCLASS), which is an indication of the proportion of the map unit, expressed as a class, that is "hydric", based on the hydric classification of a given MUKEY. (See Entity_Description for more detail). The tables were created with a set of arc macro language (aml) and awk (awk was created at Bell Labsin the 1970s and its name is derived from the first letters of the last names of its authors – Alfred Aho, Peter Weinberger, and Brian Kernighan) scripts. Send an email to mewieczo@usgs.gov to obtain copies of the computer code (See Process_Description.) The methods used are outlined in NRCS's "SSURGO Data Packaging and Use" (NRCS, 2011). The tables can be related or joined to the gSSURGO rasters of MUKEYs by the item 'MUKEY.' Joining or relating the tables to a MUKEY grid allows the creation of grids of area- and depth-weighted soil characteristics. A 90-meter raster of MUKEYs is provided which can be used to produce rasters of soil attributes. More detailed resolution rasters are available through NRCS via the link above.

Contacts

Point of Contact :: USGS-WRD MDWSC, Michael E. Wieczorek
Originator :: Michael E. Wieczorek, USGS-WRD MDWSC, Geographer
Metadata Contact :: U.S. Geological Survey
SDC Data Owner :: Maryland-Delaware-D.C. Water Science Center
USGS Mission Area :: Water Resources

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ds866_ssurgo_variables.xml Original FGDC Metadata	View	58.89 KB	application/fgdc+xml
DrainageClass.zip		3.45 MB	application/zip
HydGrp.zip		3.25 MB	application/zip
Hydrating.zip		2.38 MB	application/zip
HydricCondition.zip		3.89 MB	application/zip
Layer.zip		17.61 MB	application/zip
Text.zip		6.43 MB	application/zip
WtDep.zip		2.49 MB	application/zip
SSURGOsand.jpg		260.74 KB	image/jpeg
MUKEY90m.zip		700.86 MB	application/zip

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Illustration of data set	https://www.sciencebase.gov/catalog/file/get/631405c8d34e36012efa31ff?name=SSURGOsand.jpg

Purpose

The data were derived for use in studies requiring estimates of soil characteristics. The georeferenced soil characteristics were intended to be averaged over large areas, such as over a river basin, and used for (1) watershed simulation models that require spatially lumped estimates of soil hydraulic parameters, and (2) as explanatory variables in regional and national water-quality assessment studies.

Area- and Depth-Weighted Averages of Selected SSURGO Variables for the Conterminous United States and District of Columbia

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