Spectral and Physical Properties of Some Desert Soils: Implications for Remote Spectroscopic Terrain Analysis in Arid Regions

Spectral structure between 2.5 and 13.5 μm of a variety of soils collected from the U.S. Southwest and Saudi Arabia is shown to provide qualitative information about composition and texture. Calcite and gypsum, soil components playing significant roles in determining surface hardness, exhibit diagnostic features between 3 and 5 μm which may permit their identification via remote sensing. Gypsum also exhibits high surface reflectance at 8.7 μm; however this feature would be unreliable in a natural setting because it falls in the same spectral region in which quartz displays its strong fundamental. Silicate reflectance between 8 and 12 μm decreases with particle size; thus inferences of soil particle size and texture can potentially be made from spectral data in this region. Such information can be of military importance for forecasting regional vehicle trafficability and dust potential, often crucial concerns in the planning and conduction of tactical field operations.