Stability of tillians and impact on the road network: case of the outside basin of Ouergha (Morocco)

Abstract

The study concerns the cartography of the spatio-temporal evolution of the embankments of the road network of the Oued Ouergha watershed using data from the Landsat images on the one hand, and the modeling of soil stability processes. On the other hand. This region experiences an intense destabilization linked to the combination of several natural factors, such as the brutality and the abundance of the precipitations and the outcrop on the marls and limestones of Cretaceous. Human intervention in this vulnerable environment accentuates its fragility through the clearing and degradation of vegetation cover. The analysis of satellite data has shown that the most degraded soils are not necessarily those with the highest rate of erosion over the past fifteen years and that some well-developed soils are unstable areas after clearing and their non-rational exploitation. Human intervention and the choice of road routes sometimes, combined with climate change, remain the most important factors in weakening and increasing the vulnerability of the slopes. The results obtained made it possible to identify and monitor vulnerable zones at the Ouergha watershed scale, where interventions are needed to limit the processes of slope degradation and their impact on the various road access routes in the region.