Implementation of magnetic, gravity and resistivity data in identifying groundwater occurrences in El Qaa Plain area, Southern Sinai, Egypt (2016)

El Qaa plain is one of the areas that have been proved to be promising as to its soil and groundwater
resources in the southwestern part of Sinai. This study was carried out to study the lateral and vertical
variations in the subsurface lithologic properties in El Qaa plain area and delineating the subsurface
structure that affecting El Qaa plain depression. Gravity, magnetic data, fifty-one (51) vertical electrical
sounding (Ves’s) and Digital Elevation Model (DEM) map were used. Two-dimensional density modeling,
analytical signal, tilt derivatives, Euler deconvolution techniques and interpretation of the resistivity data
were applied on potential data. This study concluded that, El Qaa plain is a NE-SW depression confined by
two normal faults and subdivided into five sedimentary units. Rock fragments and boulders derived to
the plain from the surrounding highlands are the main components of the first surface unit that characterized
by high resistivity values. This layer is overly another unit composed of gravelly sand with thickness
ranging between 10 and 140 m. The third unit is composed mainly of sand with intercalations of clay
with thickness ranging from 2 to 152 m. A Reefal limestone unit is a fourth unit interpreted from this
study. The fifth unit is composed of clay. The water bearing formations in El Qaa Plain area are located
principally in the second and the third layers. Finally, the depth to the basement surface ranges from
400 m to more than 1.5 km below sea level. Also, there are many minor structural trends interpreted
from this study and affecting the El Qaa plain are striking in N–S, E–W and NE-SW directions.