Delineating groundwater and subsurface structures by using 2D resistivity, gravity and 3D magnetic data interpretation around Cairo–Belbies Desert road, Egypt

AbstractGeophysical tools such as magnetic, gravity and electric resistivity have been used to delineate subsurface structures, groundwater aquifer around Cairo–Belbies Desert road. A dipole–dipole section was measured at the central part of the study area with 2100m length and electrode spacing 50m for greater penetration depth. The results of the inverse resistivity data indicate that the study area includes two groundwater aquifers at different depths. The shallow aquifer water is near the surface and the deep aquifer lies at depth of about 115m and exhibits low resistivity values ranging from 20 to 100ohmm.One hundred and fifty-two gravity stations were measured using Autograv gravimeter (CG3), different gravity corrections (drift, elevation and latitude corrections) were applied. The corrected data represented by Bouguer anomaly map were filtered into regional and residual gravity anomaly maps. The residual gravity map indicates that the area is dissected by many faults with NW-SE, N-S, E-W and NE-SW trends.One hundred and fifty-three ground magnetic measurements are collected using two Proton magnetometers (Envimag). The corrected magnetic data are represented by total magnetic intensity map that was reduced to the magnetic pole. 3D magnetic modeling was applied to detect the depth of basaltic sheet and basement complex. The results indicated that the elevation of upper surface of basalt is ranging from 148 to −153m and the elevation of lower surface of basalt is ranging from 148 to 269m

Contribution of geophysical studies on detection of the Petrified Frost Qattamiya, Cairo

Different geophysical tools such as resistivity, seismic refraction, and magnetic survey have been applied to delineate the subsurface stratigraphy and structural elements, which controlled the distribution and origin of the Petrified wood in Qattamiya, Cairo, Egypt. Land magnetic survey was carried out in the study area through two stages, the first stage includes all area by measuring 11,674 stations and the second stage was carried out in the detailed area that was located at the southeastern part of the all area including 9441 stations. All measurements have been corrected for diurnal variation and reduced to the north magnetic pole. The results of magnetic interpretation indicated that the area dissected by different structural elements trend toward NE–SW, NW–SE, N–S and E–W directions. Twenty-eight samples have been collected from the detailed area to analyze for magnetic susceptibility values. Four electrical resistivity tomography (ERT) profiles were measured by using dipole–dipole configuration to estimate the vertical and lateral variation of the subsurface sequence. Results of quantitative interpretation of the ERT data indicate that the subsurface sequence consists of different geoelectric units; the first unit is characterized by high resistivity values upto 1000 ohm m corresponding to sand, gravel and Petrified wood at the surface and extends to a depth of a few meters. The second geoelectric unit is corresponding to sandy clay which exhibits moderate resistivity (few hundred ohm m) values with thickness ranging from 6 to10 m. The third geoelectric unit is characterized by very low resistivity corresponding to clay of depth ranging from 10 to 30 m overlaying the fourth unit which reached to a depth ranging from 30 to 56 m and characterized by very high resistivity (8000 ohm m) corresponding to limestone. Three shallow seismic refraction spreads of geophone spacing 7.5 m were measured to investigate the subsurface sequence, where the results of interpretation indicate that the subsurface section consists of three units of average velocity 500, 2000 and 4000 m/s, respectively corresponding to sand, gravel and Petrified wood, sandy clay, clay and limestone

Assessment of groundwater aquifer using geophysical and remote sensing data on the area of Central Sinai, Egypt

Abstract The study aims to assess groundwater resources in Sinai's central area using remote sensing, geoelectric, and well-logging data, utilising techniques for modelling hydrogeological frameworks and evaluating desert regions' groundwater potential. Its utilized satellite image sources, soil maps, and geological maps to map the effects of various factors on groundwater potentiality recharge, dividing it into five zones. Eighteen deep VES stations were used to examine the upper part of the groundwater aquifer in Central Sinai, Egypt, comparing it with available borehole information (Well-1, and JICA-1) to establish subsurface geology and hydro-geology positioning. Borehole data, VES interpretation results, hydro-geophysical maps, and four geoelectrical cross-sections were used to visualize the rearward expansion of eight lithological units, groundwater-bearing sections, and aquifer-filled thicknesses. From interpretation data output reveal three zones with significant recharge and storage potential, including two groundwater aquifers. The shallow aquifer has a saturation thickness of the fractured limestone of 35–250 m, while the deep aquifer Nubian sandstone is detected at depths ranging from 660–1030 m. NW–SE and NE–SW faults likely recharge conduits connecting shallow and deep aquifers, providing sites with acceptable groundwater potential for living, agriculture, and development in Sinai

Groundwater aquifer assessment using hydrogeophysical investigations: the case of western Al Ain Sokhna area, Gulf of Suez, Eastern Desert, Egypt

This study aims to assess the groundwater aquifer and defined the quality of water in the Gulf of Suez region. Hydrochemical and electrical resistivity techniques have been used for evaluating an aquifer, including its extension and quality, in the western Al Ain Sokhna area, Gulf of Suez. This study collected 16 groundwater samples from wells tapping the upper Miocene aquifer. Laboratory tests, including the estimation of electrical conductivity (E.C.), pH, total dissolved solids (TDS) and major ions such as Ca2+, Mg2+, Na+, K+, CO32–, HCO33–, SO42– and Cl–, were conducted. Most water samples belonged to the category of permissible water (TDS 500–1500 ppm) which represented 62.5% and brackish water which represented 37.5%. A total of 47 vertical electrical sounding stations were measured using the Schlumberger array of AB/2 up to 1500 m to detect the subsurface geologic section and delineate water-bearing layers. The results of geoelectrical interpretation illustrated that the subsurface section has five geoelectrical layers. The third layer represents the freshwater aquifer, and the fourth layer represents the brackish water aquifer. The upper Miocene aquifer represents the first aquifer with fresh groundwater of resistivities ranging from 14.7 to 100 Ω.m and thickness ranging between 28.4 and 86 m

Subsurface investigation on Quarter 27 of May 15th city, Cairo, Egypt using electrical resistivity tomography and shallow seismic refraction techniques

AbstractGeophysical tools such as electrical resistivity tomography (ERT) and shallow seismic (both P-wave seismic refraction and Multi-channel Analysis of Surface Waves (MASW)) are interesting techniques for delineating the subsurface configurations as stratigraphy, structural elements, caves and water saturated zones. The ERT technique is used to delineate the contamination, to detect the buried objects, and to quantify some aquifer properties. Eight 2-D (two dimensional) electrical resistivity sections were measured using two different configurations (dipole–dipole and Wenner). The spread length is of 96m and the electrodes spacing are 2, 4 and 6m, respectively to reach a depth ranging from 13 to 17m. The results indicate that, the subsurface section is divided into main three geo-electrical units, the first is fractured marl and limestone which exhibits high resistivity values ranging from 40 to 300ohmm. The second unit is corresponding to marl of moderate resistivity values and the third unit, which is the deeper unit, exhibits very low resistivity values corresponding to clayey marl. The fourth layer is marly clay with water. The presence of clay causes the most geotechnical problems. Fourteen shallow seismic sections (both for P-wave and MASW) were carried out using spread of 94m and geophone spacing of 2m for each P-wave section. The results demonstrate that the deduced subsurface section consists of four layers, the first layer exhibits very low P-wave velocity ranging from 280 to 420m/s, the second layer reveals P-wave velocity ranging from 400 to 1200m/s, the third layer has P-wave velocity ranging from 970 to 2000m/s and the fourth layer exhibits high velocity ranging from 1900 to 3600m/s. The ERT and shallow seismic results, reflect the presence of two parallel faults passing through Quarter 27 and trending NW-SE