The use of spectroscopy to monitor soils and soil crusts

In 1989 the European Imaging Spectrometry Airborne Campaign (EISAC) was carried out with a 63-channel scanner and a resolution of approximately 10 × 10 m. One of the test sites is located in the Ardeche in southern France. In order to contribute to image interpretation the spectroscopic behavior of five Mediterranean soil types was studied under laboratory conditions. The soils were exposed to artificial rain to stimulate crust formation. The SWIR (short-wavelength infrared) spectral reflectance of the soils and their crusts was measured. Correspondence analysis was used to determine the main classification criteria for the different soil types. Furthermore, correspondence analysis was used to determine the most important discriminating wavelengths. It was possible to distinguish two main soil types by means of calcite absorption features. Crusting of the soils could be recognized by an increase of overall reflectance (albedo) of approximately 15%.