California GAP: Download GIS Data

This page provides online access to the geographic information system (GIS) data sets developed for the California Gap Analysis Project or that are useful as reference data for viewing or analyzing the GAP data. GIS data are in ARC/INFO export file format, with the exception of satellite imagery and shaded relief data which are in generic image format and the vertebrate distribution data which are in a text format that can be linked to the land cover coverage by the polygon id for display. Files are compressed with gzip to improve data transfer rates.

We provide two alternative ways to download the data sets depending upon your hardware and your network connection: statewide data (relatively large files) or subsets by ecological region. If you need data for a large area but have slow Internet access (for example a 9600 bps modem), we recommend you order the entire CA-GAP database on CD-ROM.

We would also like to get anyone using GAP data to describe their applications. Please navigate to the National GAP web site and enter a brief summary of your project and the use of GAP data. Thanks.

Download statewide data

Download by region (Land-cover, TM imagery only)

Important Details

Before using the CA-GAP data in your own applications, we encourage you to read the section on appropriate uses and limitations of the database. Although developed for regional conservation assessment and planning purposes, the CA-GAP database has been used for many other applications. We list some of them here to stimulate ideas for additional uses.

All files are compressed with the public domain gzip function. Gzip is a public domain compression program available for unix, ms-dos and mac platforms which is similar in behavior to the unix "compress/uncompress" programs. You can obtain your own copy of gzip for your particular machine type from our archive.

Map projection parameters for all spatial data sets are:

Projection ALBERS
Units METERS
DATUM NAD27
Spheroid CLARKE1866
Parameters:
1st standard parallel 34 0 0.000
2nd standard parallel 40 30 0.000
central meridian -120 0 0.00
latitude of projection's origin 0 0 0.000
false easting (meters) 0.00000
false northing (meters) -4000000.0000

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