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.

The community of nematodes (Nematoda: Secernentea) in groves of North East Algeria, has been the subject of regular observations of September 2011 to May 2012. Sampling and extraction of nematodes by the buckets technique are conducted following the method of Baermann. The sampling groves are composed by olive trees (Olea europea: Oleaceae) from four varieties: Chemlal, Sigoise, Frontoï and Sévillane. We identified a total of 531 individuals. The systematic inventory revealed 14 genus of Nematoda, belonging to 10 families and 3 orders. The Tylenchida and Dorylaimida are the best represented orders. They represent 92.85% of the total community of all identified nematodes, while Aphelenchida represent only 7.15%. The genus Pratylenchus records alone 54.75% on the Sévillane variety and 33.02% on the Frantoi variety. The most represented genus on Sigoise and Chemlal varieties is Meloidogyne with respectively 43.24% and 30.43%. Grove of Sévillane variety hosts the highest abundance of nematodes with 57.44%; against only 19.96%, 13.94% and 8.66%, respectively, for the varieties Frantoi, Sigoise and Chemlal. Depending on the seasons, nematodes are more abundant in autumn (88.52%) than in winter (8.66%) and the spring (2.82%). Pratylenchus and Meloidogyne are noted with large numbers, especially in winter.

This research work deals with the problem of karst sinkhole collapse occurring in the last few years in Cheria area (NE Algeria). This newly revealed phenomenon is of a major constrain in land use planning and urbanization, it has become necessary to locate and assess the stability of these underground features before any planning operation. Several exploration methods for the localization of underground cavities have been considered. Geological survey, discontinuity analysis, resistivity survey [ground penetrating radar has not been used as most of the Mio-Plio-Quaternary filling deposit covering Eocene limestone contains clay layers which limits the applicability of the method (Roth et al. in Eng Geol 65:225–232, 2002)] and borehole drilling were undertaken in order to locate underground cavities and assess their depth, geometry, dimensions, etc. Laboratory testing and field work were also undertaken in order to determine both intact rock and rock mass properties. All the rock mechanics testing and measurement were undertaken according to the ISRM recommendations. It has been found that under imposed loading, the stability of the karst cavities depends on the geo-mechanical parameters (RMR, Rock Mass Rating; GSI, Geological Strength Index; E, Young modulus) of the host rock as well as the depth and dimensions of the gallery. It increases with RMR, GSI, E and depth and decreases as the cavity becomes wider. Furthermore, the calculation results show that a ratio (roof thickness to gallery width) of 0.3 and more indicate, a stable conditions. The results obtained in this work allow identifying and assessing the stability of underground karst cavities. The methodology followed in this paper can be taken as a road map in the establishment of a hazard map related to the studied phenomenon. This map will be a useful tool for the future urban extension planning in Cheria area.