LAUSR

Abstract The causes of agricultural land expansion and its impacts on dryland ecosystems such as the oasis regions of Southern Tunisia, are fundamental problems challenging the sustainability of irrigated agriculture on water limited ecosystems. Consequently, a thorough understanding of this phenomenon is necessary to avoid future problems. With the objective of identifying irrigated land expansion dynamics and the primary drivers, two representative oasis regions in Southern Tunisia, Mareth and Fatnassa, were selected. Changes in irrigated lands in both regions between 1985 and 2011 were analyzed, and the land uses from which expansion occurred were identified using Landsat images from different years (1985, 1996 and 2011). The results indicate that the surface occupied by irrigation agriculture has doubled in Mareth, while in Fatnassa, it has increased fourfold. During that period, there was a simultaneous increase in total population, as consequence of human migration that came along with an increase in income. Thus, we could identify human migration and economic development as potential drivers of irrigated agriculture expansion, though further research is warranted to ascertain a quantification that would assist in obtaining the sustainability of these regions.