Contribution of Geographic Information Systems to the evaluation land degradation and anti-erosion management in the watershed of Oued Agareb [Contribution d'un Système d'Information Géographique à l'évaluation de la dégradation du sol et des aménagements anti-érosifs au niveau du bassin versant de Oued Agareb]

The watershed of oued agareb,located on the southern coast of sfax and subjected to an irregular climate,is characterized by low topography,a soft structure and a dense river network. these factors make the watershed fragiler and thus trigger various forms of soil degradation. the present work aims to identify the different forms of degradation affecting the land in the watershed. the work also includes the assessment of erosion control works implemented in order to identify priority areas for any intervention. the study was based on the manipulation of a set of map data (topographic maps,satellite images with high resolution,etc.) in a geographic information system and the development of thematic maps. a critical review of anti-erosion interventions was well presented,followed by a reflection on the nature of action to be taken,given the scale and persistence of the degradation phenomenon registered throughout the watershed (physical,chemical and anthropogenic).