Configuration of the limestone aquifers in the central part of Egypt using electrical measurements M. M. Abou Heleika & E. Niesner Abstract The Western Desert of Egypt is an area of natural expansion for agricultural, industrial, and civil activities. This expansion has led to a great demand for groundwater. In the central part of Egypt, on the western limestone plateau, vertical electrical sounding and bore- hole geophysical logging were conducted to delineate aquifer boundaries. The measurements were interpreted using the lithological information from the drilled wells as a constraining factor. Fractured chalky limestone sedi- ments represent the main aquifer, which is covered by sand and gravel deposits and which rests directly on partially saturated and highly resistive massive limestone. Discontinuous clay layers, which overlie the aquifer unit, were detected in the southern part of the study area as well as a relatively thin marly limestone layer in the northern part. The integrated analyses carried out represent a significant and cost-effective method for delineating the main aquifer in this area. In turn, future well locations can be placed with more confidence than before, in accordance with the evaluation of the potentiality of the groundwater aquifers in the area. Although the groundwater is normally brackish, it can serve the acute demands for water, especially for agricultural purposes. Keywords Egypt . Geophysical methods . Groundwater exploration . Limestone . Agriculture Introduction Egypt is facing greatly increasing demands for water due to a rapidly growing population. Surface-water resources originating from the Nile are now fully exploited (Hvidt 1999). Great attention is now focused on groundwater extraction from the desert. The legendary fertility of Egypt is a consequence of the fact that only about 3% of the country comprises the Nile Valley and Delta but supports about 95% of Egypt’ s population. This makes it one of the most crowded areas in the world. Recently, there has been a development program of progressive reclamation and urbanization of the desert fringes of the Nile Valley including the study area. This area lies at the eastern border of the Western Desert in the central part of Egypt between latitudes 28° 00′– 28° 40′ and longitudes 30° 30′– 30° 42′ with an area of about 360 km 2 (Fig. 1). Temperatures in the area range from 41 to 9°C and the annual rainfall is about 25–50 mm, but several years may pass without any significant rain. Geomorphologically, this area is a moderately elevated plateau relative to the Nile banks and it consists mainly of limestone covered by alluvial deposits, formed from sand and gravel. It is characterized by low relief with elevations ranging between 120 and 45 m a.s.l. (mean elevation of the river banks is 35 m) with a gentle slope from south to north. In the development of the area, the government has followed a policy of giving out land concessions to private investors. Since there is an inadequate surface-water supply, the investors started speculative drilling to satisfy their demands of water for cultivation and domestic purposes. After a series of failures and successes in the drilling process, El Minia University was consulted. As a result, a vertical electrical sounding survey has since been carried out for each of the desired well sites on the concession holders’ land before drilling commenced. Also, from the drilling process, lithologic information and the depth of the water table were obtained for each well. Before this consulting program, which was in operation from 2002 to 2006, the limestone as a groundwater aquifer in this area was unknown. Since the aquifer has been explored, the rate of drilling has increased. In some localities the drilling program continued without taking the aquifer geometry and potential yields into consideration. Measured electrical data, in combination with some borehole geophys- ical data and the lithological information from the drilled Received: 6 August 2007 / Accepted: 31 August 2008 Published online: 3 October 2008 © Springer-Verlag 2008 M. M. Abou Heleika ()) Faculty of Science El Minia University Egypt, El Minia, Egypt e-mail: heleika@yahoo.com Tel.: +20-862-377118 Fax: +20-862-342601 E. Niesner Institute of Geophysics Leoben Austria, Leoben, Austria E. Niesner e-mail: Erich.Niesner@mu-leoben.at Hydrogeology Journal (2009) 17: 433–446 DOI 10.1007/s10040-008-0360-8