الفهرس 
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Abstract
This study was conducted in El-Sadat city, which is considered as one of the biggest industrial cities in Egypt. It was constructed at about 80 kilometers north-west of Cairo, along Cairo-Alexandria desert road with a total area of about 500 km2.
El Sadat city and its surroundings occupy the area bounded by latitudes 30º 15ʹ 50ʺ, 30 º 34ʹ 00ʺ N and longitudes 30º 19ʹ 30ʺ , 30 º 40ʹ 27ʺ E. Two main problems can be identified in the city. The first problem comes from the fact that there is no source for surface water. So, groundwater is the main source for water supplies needed for domestic, agricultural and industrial activities in the city. Accordingly, the unmanaged overexploitation of the groundwater led to depletion of the groundwater level which may affect the water quality. The second problem that threatens the life in the city is the possibility of groundwater contamination due to infiltration of wastewater from the oxidation ponds (2 huge lakes for collecting wastewater from all parts of the city) into the groundwater aquifer.
This study aims at characterization of groundwater occurrences in the study area, determination of the proper locations for new water wells, and investigation of the possibility/effect of the wastewater infiltration from the oxidation ponds to the shallow aquifer.
To achieve these objectives, a regional survey in the form of Vertical Electrical Sounding (VES) and Transient Electromagnetic (TEM) data were measured at 24 stations distributed in the area under consideration. Moreover, detailed study in the form of seven Electrical Resistivity Imaging (ERI) profiles and chemical analysis of ten water samples were conducted around the wastewater ponds (oxidation ponds). Two water samples were collected from the wastewater ponds and eight samples were collected from the nearby groundwater wells.
VES and TEM data were inverted individually by IPI2WIN 1-D and TEMIX XL4 programs, respectively. To obtain more accurate results, the VES models were used as initial models for inversion of TEM data. This was followed by a joint inversion of VES and TEM data sets. Joint inversion was conducted by DCEMNT code. The joint models were used for construction of three geo-electrical cross-sections describing the subsurface stratigraphic section at the study area. from the VES-TEM survey conducted at El-Sadat area, two aquifer systems could be described ; the shallow aquifer of Pleistocene Age and the deeper aquifer of Pliocene Age, where Pleistocene aquifer is the main one and it composed of sand, gravel with clay lenses. The depth to the upper surface of the Pleistocene aquifer is ranging from 6 to 36 m with resistivity varying from 27 to 115 Ohm-m and thickness from 171 to 218 m. Transverse resistance and salinity distribution maps were drawn for the Pleistocene aquifer. These maps revealed that the first priority for drilling new water wells is given to locations of soundings No. 1, 4 and 17. The depth to the upper surface of the Pliocene aquifer is ranging from 192 to 241 m with resistivity values ranging from 6 to 22 Ohm-m. It consists of sandy and silty clay deposits. Detection of the top surface of this aquifer was a big advantage as it acts as a marker bed defines the bottom of the main Pleistocene aquifer in this area.
As for the detailed survey, the ERI data inverted by using RES2DINV software and the obtained 2-D images revealed two geoelectrical units where the lower unit represents the Pleistocene aquifer. The ERI results strongly suggest a surface infiltration of the wastewater ponds to the Pleistocene aquifer. To confirm or deny the role of oxidation ponds and the infiltrated wastewater as a controlling factor for the groundwater chemistry, the water samples were analyzed for physical parameters, major cations, major anions, nutrients and heavy elements. The results of hydrochemical analysis revealed that the oxidation ponds are NOT the main controller of the ionic level distribution in the studied area. The rapid variation in the ionic dominance from sample to sample could be attributed to local, natural and anthropogenic, processes controlling the ground water chemistry in this area.