Contribution of GIS to mapping sensitivity to sand encroachment in the Boussaada sub-basin (South-west of Hodna, Algeria) using the MEDALUS approach

Desertification is a critical issue of our time, posing an immediate challenge to Algeria. The Hodna region is undergoing rapid landscape transformation due to sand encroachment. Protecting against desertification and improving the living conditions of dependent populations have become national priorities in Algeria. The aim of this study is to assess desertification sensitivity, develop a set of thematic maps (such as vegetation quality map, soil quality map, etc.), and create a database (DB) of the study area using Geographic Information System (GIS) based on the MEDALUS (Mediterranean Desertification and Land Use) approach. The Desertification Sensitivity Index (DSI) is mapped by combining four major indicators: Soil Quality Index (SQI), Climate Quality Index (CQI), Vegetation Quality Index (VQI), and Anthropogenic Quality Index (AQI). Analysis of the desertification sensitivity map of the Boussaada sub-basin identified five zones: very sensitive, sensitive, moderately sensitive, less sensitive, and non-sensitive. The map shows that three-quarters of the Boussaada sub-basin, totaling 76%, are classified as sensitive to very sensitive to desertification. The area is characterized as pre-desert due to its arid climate with low and irregular precipitation, as well as poor land management practices.