Methods of Determining Playa Surface Conditions Using Remote Sensing

摘要

Playas (dried lakes) commonly found in arid regions are geomorphic surfaces of importance for military and civilian use as aircraft landing sites, areas of easy or difficult vehicular movement, sources of dust produced by vehicles or munitions, and as a source of chemical and mineral deposits. The ability to remotely detect and determine the surface character of playas is of concern to the modern Army in preparing terrain intelligence for desert operations. To this end, 20 Mojave Desert playas were sampled and classified as to surface type, ranging from hard and dry to wet and soft. Spectral reflectance measurements were collected using a Geophysical Environmental Research IRIS MkIV spectroradiometer over the 400 to 2500 nm spectral range. This range includes the non-thermal bands of Landsat TM and all the bands of the Airborne Imaging Spectrometer (AIS). Physical and chemical analyses of the surfaces were compared to the spectral curves and to the surface character of the playas. Air photo pattern analysis was also used to determine special patterns associated with the surface types. The results show limited success in assessing the mineralogy important to surface hardness. The relative moisture conditions could be detected using reflectance spectra in the short wave infrared region and gypsum surfaces could be determined. The use of the spectral data in conjunction with air photo pattern analysis gave the best results for determining surface conditions.