Geographic information system (GIS) and remote sensing for multi-temporal analysis of sand encroachment at Oglet Merteba (South Tunisia)

Sand encroachment in South Tunisia is one of the most serious environmental problems. Close to six decades, several irrational human activities are responsible for the increase in the magnitude of sand encroachment. They include overgrazing, denudation of vegetation cover and many other disturbances of the fragile arid ecosystem. Mapping this phenomenon is now essential for a better understanding of the general evolution of this process to setup and implement efficient protection techniques. The study done in the “Oglet Merteba” area was performed using the geographic information system (GIS) and remote sensing techniques particularly those referring to change detection. This kind of approach integrates direct and calculated environmental parameters in a geo-referenced data base, allowing the spatial and temporal analysis of the evolution of this phenomenon. The results show that despite the multiple efforts put together to control wind erosion, areas prone to wind erosion increased from 5 % in 1975 to 6.7% in 2006. The most important progression rate is noticed between 1987 and 2000.Key words: South Tunisia, sand encroachment, geographic information system (GIS), remote sensing, change detection, progression rate