Groundwater and Characteristics of the Tertiary-Quaternary Aquifer System West of Mallawi, Upper Egypt

Abstract

The desert areas in Egypt are suffering from the water shortage, so the groundwater exploration is the main solution for water demands in such areas. The area west of Mallawi, Upper Egypt is considered one of the promising areas for sustainable development. Mallawi area is located to the west of the Nile valley and is bounded by latitudes 27° 23′ 00″ and 28° 00′ 00″ N, and longitudes 30° 25′ 47″ and 31° 00′ 00″ E. The area is arid to semi arid, hot climate, dry, rainless in summer, and mild with rare precipitation in winter. In such area, the groundwater is the only source for sustainable development. So, the evaluation of the groundwater is necessary, where it is characterized by good water potentialities through the existing of three aquifers. These aquifers are; Quaternary sand and gravels, Oligocene-Pleistocene gravels and Middle Eocene fractured limestone. The Quaternary aquifer in the flood plain is considered as highly productive where the aquifer has an average transmissivity value of the order of 8906 m²/day and average specific capacity of 25 m³/h/m. The water salinity of this aquifer ranges between 203 and 549 mg/l and increases westward. The second aquifer; Oligocene-Pleistocene aquifer is moderately productive aquifer having an average transmissivity value of the order of 3291 m²/day and hydraulic conductivity ranges between 13.22 and 59.9 m/day and average specific capacity of 9.6 m³/h/m. Its saturated thickness ranges between 91.5 and 113.5 m and its salinity ranges between 719 and 801 mg/l. The third aquifer; the Eocene fractured limestone aquifer is considered as highly productive aquifer where it attains an average transmissivity value of the order of 6091 m²/day and average specific capacity value of 208 m³/h/m. In this aquifer, the water salinity ranges between 462 and 845 mg/l. The geologic structures play an important role in the direct hydraulic connection between the three aquifers, where; the Eocene fractured limestone aquifer is recharged directly from the Quaternary aquifer and then acts as a rechargeable source for the Oligocene-Pleistocene aquifer. The general flow direction of the groundwater is from east to west with some local change in the Eocene fractured limestone aquifer where there is a flow direction from southwest to the northeast direction which may be attributed to the over-exploitation in this locality or the effect of the fractures orientation in this aquifer system. Groundwater salinity in the three dominant aquifers generally increases westwards; i.e. in the same water flow direction.