The analysis of spectroscopical data to map soil types and soil crusts of Mediterranean eroded soils

A study was carried out to investigate the potential use of imaging spectroscopy for mapping erosion hazard in Mediterranean areas. In the study area in southern France five soil types are recognized showing different vulnerability towards erosion. Samples were taken to the laboratory and exposed to artificial rainfall to stimulate crust formation. In the laboratory the spectroscopical behaviour of the soils with and without crusts was measured in the near and shortwave infrared in very narrow bands. Correspondence analysis was used to analyze the soil physical data and the soil spectra. This multivariate analysis method was useful to select spectral bands on which to focus to discriminate between the different soil types. Two important soil types having different vulnerability towards erosion, were discriminated by absorption features of iron and calcite. Crusting of the soils was not recognized by spectral absorption features, but generally crusts caused an increase of albedo of approximately 12%. This increase of albedo might be used to assess the presence of crusts. It was concluded that some main soil types can be discriminated by spectral absorption features and that imaging spectroscopy might have a good potential for surveying the hazard of physical soil degradation in Mediterranean areas.