ARSF project ET07/05: Determining engineering parameters of expansive soils using an integrated airborne and field spectroscopy and geophysical dataset. Led by: Dr. Graham Ferrier, Department of Geography, University of Hull, Hull, HU6 7RX. Location: Mojo, Ethopia.

Conventional methods of assessing the geotechnical properties of expansive soils are expensive, time consuming and provide only sparse point samples. The presence, nature and spatial distribution of these soils can be overlooked leading to inadequate surveying of construction sites, inappropriate design specifications and subsequently result in damage to life and property. There was therefore an urgent need to develop a methodology that could accurately map these soils types, over large areas at low cost. Reflectance spectroscopy has been demonstrated to have the capability to identify and quantify specific engineering parameters of expansive soils. As the geotechnical problems of expansive soils are not only lateral, three-dimensional subsurface information was required and the vertical variation in properties of expansive soils needed to be resolved to provide engineers with more information. The aim of this project was to develop empirical models for quantitative measurement of engineering parameters of expansive soils from spectral reflectance. Ground geophysical survey data were integrated with the results of the remote sensing study to develop a generalised 3D subsurface profile model to resolve the thickness and variability in properties of expansive soils. Integration of results from the airborne study was used to calibrate measurements from satellite imagery.