Spatio-Temporal Monitoring of the Meskat System Distribution in the Tunisian Sahel Region Using TM Landsat Images

The Meskat system, which is an ancestral anti-erosion practice, has faced abandonment in the last decades. The present study is intended to monitor the spatial and temporal evolution of the Meskat system in the region of Sousse (Tunisian Sahel). Satellite images from the Landsat Thematic Mapper (TM) 5 sensor were used for four years of 1987, 2003, 2007 and 2011. The detection of land use changes was applied with the Geomatica Focus software, based on a supervised classification. Analysis of land use validation and classification highlighted nine land use classes, with an average global success and Kappa indexes of, 86 and 84%, respectively. Results of the space-time evolution of the Meskat system showed that it is mainly divided among three watersheds: Sabkha Halek El Menjel, Wadi Laya El Hammam and Wadi Hamdoun. The diachronic analysis of these three watersheds classification between 1987 and 2011 revealed an expansion of urban areas at the expense of the Meskat system. Indeed, urban areas recorded an increase of 1, 8, and 4%, while areas occupied by Meskat system were decreased by 6, 8, and 13% for the Sabkha Halek El Menjel, Laya El Hammam Wadi and Hamdoun Wadi watersheds, respectively.