Located in the Aures mountains Foum Toub is characterized by an annual average rainfall of  800mm. The hydrology subordinate to the terrain is the direct consequence of surface waters and of snow melting from the heights of Chelia Mountain. The aim of the implantation of the Foum Toub backwater is to minimize the siltation phenomenon at the upstream of the Koudiate El Mdaour dam, to regularize the Rebaa creek flow which runs from south to north and to contribute to the irrigation of the Foum Toub plain. This study puts the emphasis on the mobilization of surface water resources, a policy of the Ministry of Agriculture and Rural Development with a view to rationalize the use and planning of this vital factor, i.e. water. The site selected for the construction of this structure is characterized by a waterproof marly substratum, favourable for implanting the dike and the basin. The clay-silty-gravelly material furniture localized in the depressions as well as sandstones are used as areas for the construction materials of this structure. Stability is one of the most important parameters to take into account for the choice of the site, so as to avoid any problem linked to the withdrawal-swelling phenomena on the banks of creek. However, the sliding possibility, however weak it is, can be generated on the left bank of the creek within deposit and recent silt. The choice of the site for the implantation of this hydraulic structure remains subject to laboratory tests.