Being seen needs in increasing waters in our contry for fine domestics, manufacturs and agricultural, the prospecting of subterranean waters by geologic and hydrogeologic classic method remains inaplicable in the cases of the regions where one does not arrange drillings or polls (soundings) of gratitude (recongnition) in very sufficient (self-important) number.

In that case of figure, the method of prospecting geophysics such as the method of nuclear magnetic resonance (NMR) and the method of the geophysics radar are usually used most usually because they showed, worldwide, results very desive in the projects of prospecting and evaluation of the ressources in subterranean waters.

In the present work, which concerns only the methodology of the electric resistivities, we treat the adopted methodological approach and the study of the case of application in the turonien aquifer in the plain of Tadla and the tray of phosphates.

The adopted methodology has to consist at first in realizing a study of regional synthesis of the sector of study notably the geology of surface and sub-surface and the hydrogeology. The second phase has to consist in realizing on one hand the systematic partner of the electric polls (soundings) following a meshing dictated by the study of synthesis and on the other hand the electric etalons polls (soundings) and of wedging respectvely on the geologic emergences and on the drillings, polls (soundings) or well which are in or in the neighborhood of the sector of study. The ultimate phase has to consist in interpreter and to exploit (run) the data of the electric polls (soundings) dy specific software.

As for the application in the turonien aquifer, we indicate that sectors can vassed by this method allowed results very ecisive with geo-electrics profiles perfectly identical to the geologic cups (cuttings) abtained by correlation of the data of drillings. Also, the contribution of the present methodology in the gratitude (recongnition) of the aquifer turonien materializes in the fact which she allowed to show that the productivity of this aquifer decline of the north sounthward. This deminution of productivity, dictated by the deminution of the transverse résistance, is due to the lateral variation of the geologic facies which become more and more marly southward.