UPDATE 2004: THE INSTRUCTIONS BELOW ARE NO LONGER VALID, CLICK
THE LINKS ABOVE FOR INFORMATION ON SSURGO SOIL DATA. TO OBTAIN A COPY OF DIGITAL
SOIL DATA FOR EASTERN MASSACHUSETTS IN MASS STATE PLANE COORDINATES
CLICK HERE.
The following are step by step instructions for downloading
SSURGO certified soil data from the Internet. It is assumed that
the user has experience using GIS and is familiar with soil
survey information. These instructions are for using the ArcView
GIS software from ESRI to view
the maps but other GIS programs should also work. There are also
numerous shareware GIS programs available for free, which should
also work. If you plan on using the soil coverages with the MassGIS Data
Viewer, you should request the soil data on CD in Arc format
this way the coverages will overlay and join accurately.
Following these instructions are directions on how to change
projections using an ArcView script but this does not always work
and the coverages may not join.
These instructions are a bit lengthy so you may want to print
this out:
If you need more information about SSURGO try exploring
this site, there is a lot more information there.
Download the Soil Survey Geographic Data Base users guide
for reference (VERY IMPORTANT).
Fill out the information request form (optional) this
will provide the agency with information to aid in future
developments of the program. Select "Download SSURGO
data", this will take you to: ftp://ftp.ftw.nrcs.usda.gov/pub/ssurgo/online98
(of course you can always just click here to jumpstart
once you are familiar with the web site structure.
From here click on the (directory) Data Folder (data is
alphabetized by State, scroll to MA610 for - Hampden and
Hampshire Counties, Massachusetts or MA616 for - Norfolk
and Suffolk Counties, Massachusetts
From this site you will find the following zip files for
downloading (note: some of these are very large files):
cov.zip dlg27.zip: Digital line graph, NAD 27. dlg83.zip: Digital line graph, NAD 83. Doc: Links to metadata. out.zip: Arc/INFO export files (.e00) readme: Complete information on SSURGO structure. tab: Links to each interpretive data text files
such as map unit, yields, etc.
Download the out.zip file to a directory on your
hard drive. This file has the Arc/INFO export files (Arc
interchange format) which will be imported into the
ArcView program.
Once the file has been downloaded extract the zip file
using a zip program. There should be numerous files
ending with the extension .e00 such as interp.e00, and
mapunit.e00. Each of these files can be converted to
coverages and/or tables and used in the ArcView program.
You can import the soil mapping coverage by either a
specific USGS Quadrangle or by the entire county. If you
have a lot of memory and a fast computer you may want to
import the whole county, this is stored in the file ma610_a.e00
(Hampden and Hampshire counties) or ma616_a.e00 (Norfolk
and Suffolk counties). If you are only working in a small
area you can import a specific USGS Quadrangle, these
files are labeled with a lowercase s followed by a number
such as s4107106_0a.e00.
A brief description of the naming convention for
individual quads are as follows:
Sample File Name: tyyxxxzz_qt t - indicates type of data (s = SSURGO) yy - indicates southeast latitude of the one-degree
block in which the quadrangle resides. xxx - indicates southeast longitude of the one-degree
block in which the quadrangle resides. zz - is the 7.5-minute section number of the one-degree
block in which the quadrangle resides (reading left to
right from northwest corner). _q - indicates the 3.75-minute quarter of the 7.5-
minute quadrangle expressed as an integer (7.5-minute
quadrangles are coded as "0")
NE - 1
NW - 2
SW - 3
SE - 4 t - indicates data type: (a - soil polygons, p -
special soil point features, l - special soil line
features).
To view the coverages in the ArcView program use the
Import71 utility that comes with the Arc/View program (Start-
Programs- ESRI- ArcView Version 3.0- Import71). Specify
the export (.e00) file you want to import, then select
the directory to put it into. Data coordinates for Arc
interchange files vary with the geographic extent.
Coordinates for quadrangle coverages are in UTM meters.
Coordinates for survey area wide coverages are in
Geographic decimal degrees. Both are referenced to the
North American Datum of 1983. As mentioned earlier these
coverages may not overlay onto the MassGIS data viewer
because of differences in quadline clipping and
projections, you should order the soil coverages CD from
MassGIS to match the data viewer.
The coverage you just imported can be viewed using the
ArcView program. Start ArcView, click on the "ADD
THEME" button and navigate to the directory you
imported the file to. The only information you will get
from the soil maps is polygon information and a map unit
symbol such as "310B", this is the State-wide
map unit symbol. To view the map unit symbol double click
the soil coverage (or select "THEME", "EDIT
LEGEND"), in the "LEGEND TYPE", select
"UNIQUE VALUE", then under "VALUES FIELD",
select Musym. To show more information such as
interpretive maps or various theme maps you will need to
join the soil map attribute table with other tables
downloaded with the soil coverages. The common field to
join tables should be the Musym field.
Using
SSURGO data with other data available from the Mass/GIS
Data Viewer
If you try to overlay the SSURGO soil maps with other
maps on the Mass/GIS
data viewer the maps may not be aligned. This is
because they may be in different coordinate systems.
SSURGO data is in UTM coordinates and Mass/GIS data is in
Mass. State Plane, NAD 83 coordinates. To overlay the
maps you need to match coordinate systems, here's how:
NOTE: If you have arc/view 3.1 or
greater, use the projection utility wizard to reproject
your data from UTM to State Plane.
There is an Arc/View extension called prjctr.avx which
comes with the program, this is a very useful extension
used to change map projections to various coordinate
systems. The prjctr.ave extension is not one of the
default extensions on the Arc/View progam so you will
need to make it one. To do this use Windows Explorer to
drag the extension into the Ext32 folder. The prjctr.avx
file is in the C:\ESRI\AV_GIS30\ARCVIEW\Samples\ext
directory. Simply locate this file and drag it into the C:\ESRI\AV_GIS30\ARCVIEW\EXT32
directory. Exit Windows Explorer and start Arc/View.
Click on the File, then Extension menu and click on
Projector!
Next, add the coverage you want to convert to the State
Plane coordinate system. You must first select units for
the View, click on View, then Properties, then under Map
Units select Meters, do the same with Distance Units.
Make the Theme active, click on the change projection
icon/button (this is the projector extension you just
added, should be a button with an arrow pointing north).
When you click the projector button it will ask you to
select the input projection in the next dialog box, click
OK. Under the Category, select UTM, under the Type box
select Zone 19 for the Norfolk County data or zone 18 for
H&H, click OK, it will prompt you to pick out-put
units, select meters, click OK. Next you will select the
projection properties: under Category select State Plane
- 1983, under type select Massachusetts Mainland, click
OK.
It will ask you if you want to recalculate area,
perimeter, etc, click OK then it will ask if you want to
add projected shapefile as them to view click OK. Give
the theme shape file a name then click OK.
This new shape file is now in Massachusetts State Plane
coordinates NAD 83 and should overlay or match in with other data
available from MASSGIS such as the orthophotos, scanned usgs
topos or other theme/data.
