Digital soils survey map of the Patagonia Mountains, Arizona

The ‘Soil Survey of Santa Cruz and Parts of Cochise
and Pima Counties, Arizona,' a product of the USDA’s
Soil Conservation Service and the Forest Service in
cooperation with the Arizona Agricultural Experiment
Station, released in 1979, was created according to
the site conditions in 1971, when soil scientists
identified soils types on aerial photographs. The
scale at which these maps were published is 1:20,000.

These soil maps were automated for incorporation into
the hydrologic modeling within a GIS. The aerial photos
onto which the soils units were drawn had not been
orthoganalized, and contained distortion. A total of 15
maps composed the study area. These maps were scanned
into TIFF format using an 8-bit black and white drum
scanner at 100 dpi. The images were imported into ERDAS
IMAGINE and the white borders were removed through
subset decollaring processes. Five CD-ROM’s containing
Digital Orthophoto Quarter Quads (DOQQ’s) were used to
register and rectify the scanned soils maps. Polygonal
data was then attributed according to the datasets.