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|Title:||Classification of infiltration characteristics of depressions in landfill covers using uncalibrated, thermal-infrared imagery|
|Author(s):||Stohr, Christopher Joseph|
|Doctoral Committee Chair(s):||Darmody, Robert G.|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Landfill covers are intended to promote runoff and prevent water infiltration into the wastes. Water infiltrating through an earthen cover can mix with the wastes causing an undesirable increase in the amount of leachate and methane generated by decomposition. A common failure of the design is the collection of runoff in depressions developed in the cover.
This study developed a two-step remote sensing method to classify depressions developed in covers of two landfills: (1) manual delineation of depressions by stereoscopic, aerial photographic interpretation followed by (2) classification of depressions according to infiltration characteristics using uncalibrated, nighttime, airborne, thermal IR imagery.
Classification of depressions into two types, I and II, was made by comparison of mean values of the digitized numbers (exitance) inside of a depression with those of the summit. Type I depressions exhibit relatively low thermal exitance presumably because evaporation cools the surface of the moisture-retaining soils in the depression. Type II depressions were defined as exhibiting little or no difference in thermal exitance from the surrounding ground. This is due to the little or no moisture retained in the surface soils after relatively rapid infiltration and water redistribution through the soil profile.
At Landfill A, 24 Type I and 6 Type II depressions were classified. Thirty depressions at Landfill B were classified as Type I and 29 were classified as Type II. Five depressions at both landfills were selected for detailed field study. Bulk density of undisturbed samples taken from depression, summits, and slopes were less in Landfill B than Landfill A. Infiltration and hydraulic conductivity values of Type I and II depressions were not significantly different for either landfill. However, those values were significantly different between the Type I depressions dominating the study area of Landfill A and Type II depressions which predominated the study area of Landfill B.
Originally it was hoped that remote-sensing classification of individual depressions could be used to infer infiltration characteristics of individual depressions, however, field measurements of infiltration and hydraulic conductivity did not support that hypothesis. Nevertheless, when depressions were examined as aggregate features interpreted as having a dominant type for a particular part of a cover, results of infiltration and hydraulic conductivity tests support the hypothesis. The method shows promise for permitting early detection of areas of greater infiltration in landfill covers revealing where repairs would be most effective.
|Rights Information:||Copyright 1996 Stohr, Christopher Joseph|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9712447|