Journal of applied Geophysics, vol. 10, No. 2 Septembe (2011), 201 – 218. 1 DELINEATION OF THE DIRECTION OF FRACTURE SYSTEM AND ITS IMPACT ON THE GROUNDWATER POSSIBILITY AROUND GEBEL EL-MINSHERAH USING GEOELECTRICAL METHODS 1D, 2D AND 3D- CENTRAL SINAI - EGYPT Al-Abaseiry A. Abdel Rahman, Mostafa S. M. Barseem and Ahmed N. El Sayed Geophysical Exploration Department, Desert Research Center, Matariya, Cairo, Egypt ABSTRACT The growing activities in this promising area have caused an ever-increasing need for water resources. Detailed geoelectrical exploration is a suitable technique to achieve such an objective. The study area lies in the central part of Sinai Peninsula, around Gebel El Minsherah and north Wadi EL Brouk, between latitudes 30º 3′ 00′′ & 30º 19′ 00′′ N and longitudes 33º 25′ 00′′ & 33º 45′ 00′′ E to the south of EL Hassana City by 25 km and lies between both El Hassana – Nekhel and El Hassana – Sader El Hittan roads. The present study deals with the application of different geoelectrical exploration techniques with the main objective of investigating the impact of the geologic structural elements on the groundwater occurrences in the study area. Geomorphology, geology and hydrogeology of Central Sinai background furnished the basic information to facilitate the interpretation of the geoelectrical data. A total of 20 vertical electrical resistivity soundings (VES) were distributed among the study area. The resistivity sounding data have been qualitatively and quantitatively interpreted. The qualitative interpretation gave information about the number and continuity of the layers throughout the evaluated section. The data of the existing boreholes were used to construct the initial model for the quantitative interpretation. The details of the findings from the quantitative interpretation of the geoelectrical resistivity sounding data were discussed in terms of geoelectrical parameters of the resulting geoelectrical layers. The resistivity was related to lithology, according to the geologic information of the nearby wells. The general geologic setting and structural elements were visualized and described in view of a number of geoelectrical profiles crossing the investigated sites in various directions. The interpretation results of the geoelectrical resistivity sounding measurements along with the constructed geoelectrical cross sections and the structural contour maps revealed the number of layers, the structural elements and the groundwater occurrences in the investigated area, Six geoelectrical layers were identified, the last layer was divided into three zones (upper, middle and lower) in which the middle zone has resistivity values ranging from 15 to 50 Ohm.m., in which the associated fractures in limestone are saturated with water. The area was found to be affected by a major fold and four normal faults (F1, F2, F3 and F4), which account for groundwater occurrence with different saturation degrees.