Soil Type Mapping

Can you locate the untrafficable soil?
This Landsat Thematic Mapper image covers an area of over 31,000 square kilometers in western New Mexico. As part of a military function (Intelligence Preparation of the Battlefield) it was desired to locate occurrences of a particular soil type which could impede off-road trafficability by heavy vehicles in wet conditions. Can you delineate these areas?

IMAGINE Subpixel Classifier did!

Includes material © Space Imaging L.P.

Objective
Identify areas that may be untrafficable by heavy vehicles under wet conditions.

Approach
A signature developed with IMAGINE Subpixel Classifier was used to search this Landsat image for occurrences of a particular soil type that would not be stable during inclement conditions.

Challenges
· A large geographic area needed to be covered and access was very limited
· Complete soil map coverage was not available
· Field soil sampling techniques are extremely time consuming and expensive
· Underlying soil is often obscured by vegetation or man-made materials
· Soil type differences can be very subtle spectrally

Solution
IMAGINE Subpixel Classifier was used to map occurrences of a soil type considered to be indicative of unstable conditions that could impede trafficability by heavy off-road vehicles. The results obtained here were compared to coarse resolution geologic maps (the only relevant maps available), and a high degree of agreement was found. A few areas were spot checked with ground survey with similar results.

Technical Notes
Soil type information is also useful to farmers and land developers. The quantitative pixel fraction information provided by IMAGINE Subpixel Classifier indicates the amount of each pixel where a soil type exists. Subpixel analysis can be used to distinguish a particular soil type even when it is covered by or mixed with a variety of other materials. The presence of the soil type is useful in mapping the extent of a particular soil profile.