Spatiotemporal changes of desertification degree in the Algerian green barrier over the last four decades (1984–2020)

Abstract

Desertification is a major challenge for the sustainable development of arid and semiarid regions worldwide. The major novelty of this study lies in assessing, for the first time, the desertification degree changes in the Algerian green barrier using remote sensing and the Analytic Hierarchy Process (AHP) approach from 1984 through 2020. Four widely used remote sensing indices (LSA, NDVI, TGSI, and PDSI) were used in the Google Earth Engine (GEE) cloud computing platform as indicators of desertification in the study area. The results of the accuracy assessment of the generated desertification degree maps for 1984, 2000, and 2020 show high Kappa coefficient values exceeding 80%. Overall, the degree of desertification of the green barrier increased from 1984 to 2020. The area of medium degree has decreased from 15393.21 km2 (37.70%) to 9624.43 km2 (23.57%) between 1984 and 2020, respectively; whereas the area of high degree has increased from 23907.08 km2 (58.55%) to 30502.52 km2 (74.70%) for the same period. The combination of remote sensing and the AHP technique has proven to be effective in the spatiotemporal monitoring of the desertification degree particularly in data–scarce regions. Our findings emphasize the high expansion of desertification across the green barrier area, which information is essential for adopting adequate strategies for desertification control in the future.