Research opportunities for studying land degradation with spectroscopic techniques

Desertification is a land degradation problem of major importance in the arid regions of the world. Deterioration in soil and plant cover have adversely affected nearly 70 percent of the drylands as mainly the result of human mismanagement of cultivated and range lands. Overgrazing, woodcutting, cultivation practices inducing accelerated water and wind erosion, improper water management leading to salinisation, are all causes of land degradation. In addition to vegetation deterioration, erosion, and salinisation, desertification effects can be seen in loss of soil fertility, soil compaction, and soil crusting. Combating desertification involves having an accurate knowledge on a current land degradation status and the magnitude of the potential hazard. We present here a new project that aims at deriving a global simplified Land Degradation Index (LDI) from hyperspectral remote sensing data. Indeed, specific soil properties directly linked to soil degradation status, such as chemical properties, organic matter content, mineralogical content, soil crusting, and runoff, as well as vegetation content and degradation status, could be derived from high-spectral resolution imagery. Then, global maps assessing drylands desertification status could be routinely developed. This paper, after a brief review of land degradation processes and assessment, discusses the capabilities of hyperspectral imagery for land degradation assessment.