Abstract
The 23 and 29th September, 2016, the phenomenon of "Back to East" is caused in the region of Sousse in Tunisia, pouring rains, risings, floods and significant socioeconomic and environmental impact. The recorded dramatics damages are determined by the importance of precipitations, by the concentration of the water and by the shape of the catchment areas. Also, in the peripheral urban areas, these damages are worsened by an abandonment of the traditional hydro-agricultural works especially the "Meskat-Mankaa". Today, the urban areas became vulnerable to the normal quantities of the rains and more vulnerable with the strong rains. In this article, we show in particular that the urbanization modifies the components of the flows by increasing the surface streaming, and we test the assumption that the damage related to the floods is attached to the failures in the urban planning more than the intensities and quantities of the rains.