Landslides hazard zones’ mapping on the Melah Watershed, Governorate of Jendouba, Northweast of TUNISIA

摘要

Landslides are the major natural hazards among other hazards, leading to downward to outward movement of slope forming materials due to gravity and are particularly dangerous in the case of highways, railroads and dam reservoirs. Landslides characterizing infrastructures of mountains of the governorate of Jendouba, which are developed in massives formed by clay-sandstone levels alternated by fractured bedrock (Flysch Numidien), constitute complex systems of instabilities controlled by many factors. Remote sensing, GIS (geographic information system) and digital terrain modeling are the best application to have different thematic maps. An integration of geological, cartographic and spatial data enabled us to have a geographical and qualitative analysis of RN17 road’s landslides and a clear visualization of the spatial distribution of its predisposition factors along the Melah Watershed in the NW Tunisia. Thus, these combined techniques and methods allowed us the development of a GIS facilitating the mapping of factors controlling ground slides. A terrain motion vulnerability map is then generated, based on field missions, SRTM satellite data and basic mapping documents within a GIS environment. A spatial analysis and semantic queries shows that maximum landslide prone area is noticed beside the RN17 road. In fact, the inventoried disorders are located on clayey and clayey-sandstone sides along the slopes of the Melah basin, near the tributaries of the slopes and water sources, and especially at the level of previously fractured outcrops. In addition, stabilization studies, based on the results of the geotechnical calculations, recognize these factors (lithologic, hydrographic and morphotectonic factors) as the main precursors for these disorders. So, the solution of Wireless Sensor Network (WSN) system implemented all along the road RN17 and on very high-risk zones, may save more lives and may make smooth transportation system.