Mapping Variation in Soil Volumetric Shrinkage Using Aster Imagery

The first stage of any major civil engineering project generally involves some form of preliminary reconnaissance study of project sites followed by detailed geotechnical investigation. Primary aim of this study is to collect data concerning physical characteristics of terrain and ground conditions in order to assess their likely influence on the overall design and performance of infrastructures or vise versa. Potential problems that could eventually affect design, performance and life time of infrastructures are best determined during pre-design and preliminary design phases when compromises can be made between structural, architectural, mechanical, and other aspects of the design without disrupting design processes. Changes during detailed design phase or during construction will probably delay construction and pose economic disadvantages. It is critical to ensure that material conditions are properly assessed in a geotechnical investigation scheme which is one of the bases for designing infrastructures. Of which is identifying expansive soils and thoroughly characterizing their geotechnical properties. Since expansive soils change their geotechnical characteristics with variations in moisture content, possible heave prediction in such soils is important. The later can be achieved through measuring geotechnical parameters of soils. There are a number of qualitative and quantitative, direct and indirect, in-situ and laboratory testing procedures available to identify and characterize expansive soils. Among which, volumetric shrinkage is a measure of decrease in volume of expansive soils upon losing moisture. The more soil testing that is done before hand, the easier it is to reduce risk in the design of infrastructure and produce economically feasible as well as environmentally compatible structures. Though, it is impractical to attempt collecting many samples over short distances and analyze them for it is costly and time consuming. Remote sensing on the other hand can give information covering a large area. It also potentially provide with a continuous representation of a site under investigation other than discrete sampling points.