Spatio-temporal structure of natural and anthropogenic land use in a semi-arid watershed: Northwest Algeria

The objective of this study is to map through multisource data, the change in land use structure and quantify its evolution around the semi-arid watershed of Wadi Sarno of Sidi Bel Abbès between 2000 and 2021. To this end, satellite images of 2000 and 2021 have been exploited by remote sensing and GIS, as well as field surveys for verification and validation of the results obtained. The methodology is based on supervised classification by maximum likelihood from the processing of satellite images. The analysis of the dynamics of land use shows that the areas of natural formations (dense forest and bare land) have decreased from 17,560 ha to 15,516 ha, that is to say, a regression of 8.04%, while the anthropised formations (Agriculture, open forest and rangeland, built-up areas, water bodies) have experienced an increase in their surface area, they have gone from 7901 ha to 9945 ha, that is to say, 10.4% of the total surface area of the basin. In the light of these results, it is possible to define priority areas for restoring degraded zones and enhancing natural formations. by giving priority to perennial crops to fix the soil in place and benefit from additional income for the region's farmers. By planting hardy species such as olives, figs, almonds, carob trees and so on. These species have proven their effectiveness and adaptation to local soil and climate conditions.