Science et changements planétaires / Sécheresse


Quantification of soil losses in the Nakhla watershed (Rif, North Morocco) Volume 14, issue 2, Avril 2003


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Université Mohammed V, Faculté des sciences de Rabat, Département des sciences de la terre, UFR géoenvironnement, risques naturels et génie littoral, Avenue Ibn Battouta BP 1014 Agdal Rabat Maroc <aitbrahifsr.ac.ma>, Direction de la planification des affaires économiques, Avenue Hassan II Km 4, Station Debbagh Rabat Maroc

This study aims at using cartography techniques such as remote sensing and Geographic Information System capabilities coupled to the Wischmeier‘s Universal Soil Loss Equation in order to calculate the annual soil loss of the Nakhla watershed and to map the regions that need urgent conservation. The average specific degradation in the Nakhla watershed is 38.7 t\ha\year and the quantity of the sediments delivered at the outlet is the 5.6 t\ha\year. This latter value is considered too small in comparison with the bathymetry value of 18.2 t\ha\year. This can be explained by the fact that the Universal Soil Loss Equation of Wischmeier is designed for the rill and sheet erosion and not for the debris flows such as those caused by the landslides frequently met in the Rif mountains.