Analysis of desertification trends in the Algerian steppe using multitemporal satellite imagery for the period 2002-2022

Desertification is a process of land degradation in which fertile land becomes increasingly dry and unproductive, eventually transforming into desert-like conditions. The Algerian steppe, due to its geographical location in arid and semi-arid regions, faces increased vulnerability to desertification, exacerbated by unsustainable exploitation and ecological degradation. In this study, we analyze desertification dynamics in this region over the period 2002-2022 using Landsat images. Our analytical approach is based on deriving a Vegetation Sparsity Index (VSI) that combines two spectral indices using linear regression. In our study area, the combination MSAVI-TGSI provides the best fit. We classified VSI values into 5 classes that represent different levels of vegetation sparsity. Although some cyclic behavior can be observed, we identified two distinct parts of the steppe: one towards the west and center, with a noticeable pattern of progressive land degradation; and one towards the northeast with steady greener conditions. In addition, after a period of fluctuating conditions, the years from 2014 onward are characterized by an overall trend of desert degradation.