APPLICATION OF DIRECTIVES PAP/RAC AND GIS FOR MAPPING FORMS OF EROSION AND LAND MOVEMENTS IN THE WATERSHED OF OUED SAHB LAGHRIK (NORTHWEST TAZA, MORROCO). MAPPING APPROACH
The watershed of Oued Sahb Laghrik is a sub tributary of the Oued Inaouène. It is characterized by a very vulnerable environment: a favorable climate (intense and concentrated rainfall). The vegetation is very low (13%), which promotes runoff, decreases infiltration and increases the morphogenic processes on slopes (erosion, landslides ...). The lithological formations are mostly marl, soft, impermeable and easily altered (54.1% of the basin). The water system is temporary and very active during rainy phases. The human intervention is very important in the degradation of the environment through a number of interventions such as plowing, overgrazing, etc.The consequences of these human actions are that the watershed of Oued Sahb Laghrik has been affected by intense erosion, the forms of water erosion (sheet erosion, rill, gully erosion, Badlands ...), ground movements (landslides, mudflows ...). This dynamic threatens more homes and infrastructure and especially the Fez-Taza highway.Sheet erosion attacks most of the watershed: 53.7% of threatened land and 18.3% for mass movements. In contrast, medium and profound ravines settle always on the banks of rivers and cover 23.6%. Badlands cover 3.8% and are still at the top of gully erosion; they are deeper. By contrast, the channels have only 0.6%
