Remote sensing and modeling of topsoil properties, a clue for assessing land degradation

Semi-arid regions are under high pressure to supply the required food for their rapidly-increasing populations. This, together with the harsh climatic conditions and changes in land use accelerates land degradation processes, which eventually leads to yield reduction. Conventional sensor systems provide data in only a few spectral bands, which can be, to a given extent, used to model the reflectance of some of the soil components. With the development of scanner systems, that acquire data in many narrow-wavelength bands, almost continuous reflectance data become obtainable, which have considerably enriched all studies of the Earth’s surface. In order to examine the capability of the narrow absorption bands three different study levels, namely spot, local and regional can be planned. At the spot level, soil properties are determined in soil profiles and in laboratory. The key narrow bands, which highly correlate with any of the soil properties, are measured in laboratory and in field. The results should give room to develop a model to predict each property from its spectral signature. The data obtained at this stage might be used to model soil structure and the affect of salinization on it. At the local level, high-resolution air-borne data together with ground-based reflected measurements and laboratory data, from previous phase, are used to determine the spectral reflectance of the salt-affected soils. Ancillary data such as spatial distribution and surface conditions of the salt-affected areas are to be correlated with reflectance data. At the regional level, multi-spectral and multi-spatial resolution spaceborne data and the data from previous phases are used to delineate salt-affected areas.