Geographia Technica, Vol. 09, Issue 1, 2014, pp 1 to 9 USING LANDSAT IMAGERY FOR MONITORING THE SPATIOTEMPORAL EVOLUTION OF SANDING IN DRYLAND, THE CASE OF IN-SALAH IN THE TIDIKELT (SOUTHERN ALGERIAN SAHARA) BOULGHOBRA Nouar 1 , HADRI Toufik, BOUHANA Mamar ABSTRACT The exposure to sanding risk in the Tidikelt plain is particularly ascribed to its physiographic and climatic conditions, the location of agglomerations, agricultural and socioeconomic activities in a corridor of severe wind action, increases the vulnerability to the risk as a response to the relentless human pressure, which is exerted on an arid environment already subject to climatic extremes. The use of remote sensing tool and the multitemporal Landsat imagery have allowed the regional and static observation of sand accumulation forms, and also monitoring the spatiotemporal dynamics of mobile dunes during 19 years. This gradual mutation still confronted with a noticeably low resilience from the population and the authorities. Key words: Sanding; Mobile dunes; In-Salah; Algeria; Landsat imagery. 1. INTRODUCTION The international United Nations convention of desertification combating, defines the term desertification as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities (UN, 1994). Currently, the subjected areas to desertification occupy 39.2 % of the globe, i.e. nearly 51.6×10 6 km² of degraded land, in which 4.86×10 6 km² in Africa (Thomas, 1995; Arar, 1993). Algeria includes large arid and semi arid areas subjected to adverse impacts of desertification; 20×10 6 ha area is threatened by wind erosion, 5×10 6 ha area is already in an advanced state of degradation (Bensaid, 2006). These spaces that are part of the Algerian Sahara which covering 200×10 6 ha (80 % of the Algerian territory) have broad aptitudes to the land degradation, i.e. paleoclimate, drought, long duration of insolation and high wind activity. This translates to increased wind erosion and therefore, amplifying the sanding risk which induces not only the decline of ecosystems, but also increased the society vulnerability to climatic risks. This is the case of the In-Salah region in southern Algerian Sahara, which offers favorable physical and climate context to wind erosion. All human and socio-economic installations in this region are located in a wind corridor of high dynamics, and then present the only stopping obstacles at the actions of moving sands, hence frequent sanding of agricultural lands, palm groves, urban agglomerations and road infrastructures. This article focuses on the diachronic analysis of the sanding evolution in the In-Salah region using remote sensing tools. The experimental approach involves the study of spatial extension and bi-temporal evolution of mobile dunes, using multitemporal Landsat imagery; the TM scene of 1987 and ETM + of 2005. After determining the physiographic and climatic abilities to sanding in the region, we proceeded to define the various components of the 1 Scientific and technical research center for arid regions (CRSTRA), Touggourt, Algeria, boulghobra.n@gmail.com, hadtoufik@gmail.com, bouhanamamar@gmail.com