Marc Salmon

Contribution of SAR interferometry (from ERS1/2) in the study of aeolian transport processes : The cases of Niger, Mauritania and Morocco

In order to face desertification and sand encroachment of interdunar depressions as well as to protect soils where food plantations are possible in the area of Gouré (Southeast Niger), it is essential to localize the origin and drift of sands. In this paper, it is showed that radar satellite remote sensing and interferometry offers the opportunity to gather all the required information. Digital Elevation Models (DEM) generated by interferometry on ERS 1-2 SAR images (a tandem pair acquired on April 25 and 26 1996) helped us collect information on relief and provided us with an aeolian model while giving us some insight into the spatial distribution of sand formations. Interpreting the interferometric coherent image by means of a color composite allowed us to detect and locate sand movements in the areas under study. This project mainly highlights the contribution of SAR interferometry in the study of sand movements by developing addedvalue products. Interpretations were validated using high resolution satellite data (SPOT 5, IKONOS, and QUICKBIRD) and field observations made during a campaign in Niger in March 2004. The same procedure was also applied in Mauritania using two tandem pairs (2-3 November 1995 and 7-8 December 1995) and in Southern Morocco (18-19 May 1996) in order to identify active dunes in these regions. These observations will be taken into account when analysing ENVISAT-ASAR data.