CLASSIFICATION OF DEPRESSIONS IN LANDFILL COVERS USING UNCALIBRATED THERMAL-INFRARED IMAGERY

A two-step analysis was used to classify depressions developed in cove rs of two landfills: (1) manual delineation of depressions by stereosc opic, aerial photographic interpretation, followed by (2) classificati on of depressions according to infiltration characteristics using unca librated, nighttime, airborne, thermal IR imagery. Depressions were de lineated as landforms according to their topographic expression using color infrared aerial photography. Classification of depressions into Type I or Type II was made by comparison of mean values of the digital numbers (exitance) inside and outside of a depression (interdepressio nal area). Samples are taken along a single scan line in order to elim inate variations caused by the gain adjustment of the scanner. Compari son of sample means of digital numbers was made using the t-test. The use of the two-step method will permit early detection of apparent inf iltration characteristics of depressions formed in landfill covers.