Journal of American Science 2015;11(6) http://www.jofamericanscience.org 281 Sea Water Intrusion in Nile Delta in Perspective of New Configuration of the Aquifer Heterogeneity Using the Recent Stratigraphy Data Nofal E. R. 1 , Amer M. A. 2 , El-Didy S. M. 3 and Akram M. Fekry 4 1, 4 Research Institute for Groundwater, National Water Research Center (El-Kanater El-Khairiya- Egypt). 2, 3 Irrigation and Hydraulics Dept., Faculty of Engineering, Cairo Univ. (Giza, Egypt). emanragab29@yahoo.com Abstract: Egypt is considered an arid country. The main and almost exclusive source of water is the River Nile. The second source of water is groundwater whereas a variety of aquifer systems exist. Nile Delta aquifer is a large freshwater reservoir which is mainly replenished from irrigation activities. A proper management and development of such aquifers should be directed to satisfy water requirements. Groundwater development in the northern region is restricted due to the risks of inland movement of saline water/ fresh water interface to properly manage groundwater in this region. To achieve the proper management of groundwater resource in this region, it is important to understand the patterns of seawater movement and mixing between fresh and saline groundwater. In order to understand the salinity distribution and seawater movement, the actual heterogeneity and stratigraphy of the Nile Delta aquifer should be determined. The conventional modeling concept of the Nile Delta aquifer had assumed the aquifer as a homogenous media of graded sand and gravel with a clay cap at the top. In this study, assessment of recent stratigraphy of the Nile Delta aquifer is carried out using litho-logical data from the new drilled groups of multi depths wells. These wells has been designed and implemented especially to investigate the actual litho-stratigraphy and heterogeneity of the aquifer in the northern and middle region of the Nile Delta as a part of National Groundwater Quality Monitoring program, by Research Institute for Groundwater (RIGW). In this study, new configuration of the Nile Delta aquifer system has been obtained by assessing the Hydro-geological stratification of Nile Delta aquifer using RockWorks software. The study concluded that the northern part the aquifer is devolved into multi-layered aquifer system while in the southern part; the aquifer constitutes sand and gravel facies. Furthermore, this study assessed the Hydrochemistry status of the groundwater in the Nile Delta aquifer by using the results of chemical analysis of multi depths points (25- 650 m) of the National Groundwater Quality Monitoring network. This assessment confirmed that there is a multi wedge system for the sea water intrusion in the Nile Delta aquifer. The shape and direction of the wedges differs between the different layers of the aquifer according to the salinity and density of the groundwater present in each layer. This new multi system wedge can be used to model and simulate the new conceptual and configuration of the Nile Delta aquifer to fulfill proper groundwater development and management. [Nofal E. R. , Amer M. A., El-Didy S. M. and Akram M. Fekry. Sea Water Intrusion in Nile Delta in Perspective of New Configuration of the Aquifer Heterogeneity Using the Recent Stratigraphy Data. J Am Sci 2015;11(6):281-292]. (ISSN: 1545-1003). http://www.jofamericanscience.org. 33 Key words: Nile Delta aquifer, Aquifer Heterogeneity, Multi-layered aquifer system, Multi sea water intrusion wedge, Sea water intrusion, Groundwater quality. 1. Introduction The Nile aquifer system in the Nile Delta is a huge groundwater reservoir extending to cover the entire Nile Delta region. Previously, most of the Nile Delta aquifer studies neglected the geological stratification inside the aquifer either for: 1. Lack of enough litho-logical stratification data for multi depths observation points, 2. Difficulty at that time of studying and simulating the aquifer with the detailed geological stratification. The aquifer was only considered in all the previous studies as a sand and gravel aquifer with a variable clay top cap. Figure (1) shows the typical cross section of the Nile Delta aquifer that was used before in most of the aquifer studies. According to this simple conceptual cross sections along the Nile Delta aquifer, the hydro- geological units that were considered in studying the Nile Delta aquifer before were summarized as follows: a. Top unit of Holocene clay aquitard; b. Quaternary and late Tertiary gravels and sands unit (aquifer); c. Basal unit of Pliocene clay aquiclude. In the last two decades, some authors have given attention to the geological history of the stratigraphy of the Nile Delta region due to the sea shore movement and the Nile river progresses and behavior during the recent thousands years. During these thousands years, the old deltatic of Nile river branches and the regression and transgression of the sea shore caused the subsystem aquifer in the Nile Delta.