‫اإلهداء‬
‫الق لب موطن الذكريات‬
‫حلوها ومرها‬
‫يطير بك على جناح السرعة‬
‫ما أن تمسه الذاكرة بعصاها السحرية‬
‫إلى عالم ساحر ف اتن‬
‫يثير في النفس الحنين‬
‫إلى كل لحظة حلوة‬
‫ف إلى كل من أهدى لنل ذكرى جميلة‬
‫والداي‬
‫وإليكما أعز الناس‬
‫‪1‬‬
Acknowledgement
We present our thanks and our appreciation to the staff of Environmental
and Earth science Department at the Islamic university – Gaza
Special thanks and gratitude for the capable Dr. Zeyad H. Abu Heen, the
supervisor,
To Engineer/ Ahmed Al Yaaqubi
To Designer/ Ashraf Al Kassas
2
Abstract
The Geophysical method is one of the successful methods to identification of the
subsurface formation, structures and economic fortunes.
In this research we were interpreted the data from Italian project by using IPI2win
program. We compared our work with American project (Black hook) and well
logging.
finally we suggested a structural model for the study area and an evaluation of the
thicknesses of the overlying layers. This suggestion model includes the following
arrangement from upper to bottom.
1- Sand layers represent the sand dunes.
2- Kurkar formation (sand stone cemented with lime, and Hamra which is red
sandy clay) which is the main aquifer of Gaza Strip.
3- Saqia formation (Sandy limestone, Limestone, Evaporates, Conglomerate,
Shall and Marl).
3
TABLE OF CONTENTS
Chapter 1: Study area
1.1 Demography of the study area
1.2 Topography
1.3 Geomorphology
1.4 Coastal Geology
1.5 Coast and sea bed characteristics
1.6 Climate
1.7 Nature Resources
1.7.1 Water Resources
1.8 Sand
1.9 Agriculture
1.10 Housing
1.11 Industry
2
2
3
3
4
5
5
5
7
7
8
Chapter2: Resistivity Survey
2.1 Introduction
2.2 Definition and Resistivity Units
13
14
2.3 Electrode Arrays
19
2.4 Resistivity Sounding and Horizontal Profiling
20
2.4.1 Sounding
21
2.5 Interpretation of Electrical Soundings, Profiling, Mapping and
Imaging
23
2.5.1 Types of theoretical electrical sounding curves over
horizontally stratified layers
25
2.5.2 Elements of Resistivity Sounding Interpretation Process of 1-D
Earth Model:
31
4
Chapter 3: Geophysical Methods Application on study Area
34
Chapter 4: Interpretation of Apparent Resistivity Field Data
4.1 Introduction and objectives of the chapter
45
4.2 Qualitative Interpretation of Apparent Resistivity cross–sections
46
4.2.1 NorthWest – South East pseudosections
49
4.2.2 North East – South West Pseudosections
54
4.3 Quantitative Interpretation of Apparent Resistivity Field Data
4.3.1. Interpretation of sounding curves
4.3.2 Geoelectrical Cross sections interpretation
57
57
110
4.3.2.1 North Wes–South East cross section
110
4.3.2.2 NE–SW Cross section
115
Chapter 5:
Conclusion
119
References
120
Appendix
122
5
LIST OF FIGURES
Chapter 1
Figure 1.1: Location map of Gaza Strip
Figure 1.2: Location map of the study area
Figure 1.3: Geologic Sketch Across Gaza Governorates
Figure 1.4: Generalized Stratigraphic Column
9
10
11
12
Chapter2
Figure (2.1): An electrode at origin O of a co-ordinate system. S is the surface of a
sphere of radius r.
16
Figure (2.2): Two current and two potential electrodes on the surface of a
homogeneous isotropic earth.
17
Figure (2.3): Electrode configurations used in electrical resistivity surveys and the
corresponding apparent resistivity equations
20
Figure (2.4): Proportion of current flowing below depth z ; AB is the current electrode
half-spacing.
22
Figure (2.5): Resistivity sounding curve showing apparent resistivity as a function of
current electrode half-separation (AB/2)
23
Figure (2.6): The three different models used in the resistivity measurement
interpretation.
Figure
(2.7)
25
Two-layer
ascending
and
descending
type
master
curves.
28
Figure (2.8): Three-layer type curves.
29
Figure (2.9): Nature of four-layer type curves:. A) HA- and HK-type; B) QH- and
QQ- type; C) KH- and KQ-type; D). AA- and AK type.
30
Chapter 3
Figure ( 3.1) : Location map of VES
35
Chapter 4
Figure ( 4.1.A ) : Location map of cross section profile P
47
Figure ( 4.1.B ) : Location map of cross section profile C
48
Figure ( 4.2): Resistivity pseudo cross-section for ( P1-P1\ ) to ( P3-P3\ ). (a) Pseudo
cross- section( P1-P1\ ) , (b) Pseudo cross- section ( P2-P2\ ) ,(c) Pseudo cross- section
( P3-P3\ ).
52
6
Figure ( 4.2 ): Resistivity pseudo cross-section for ( P4-P4\ ) to ( P5-P5\ ) .(d) Pseudo
cross- section ( P4-P4\ ), (e) Pseudo cross-section ( P5-P5\ )
56
\
\
Figure ( 4.3 ): Resistivity pseudo cross-section for ( C1-C1 ) to ( C4-C4 ). (a) Pseudo
cross- section profile ( C1-C1\ ), (b) Pseudo cross- section profile ( C2-C2\ ), (c)
Pseudo cross-section profile ( C3-C3\ ), (d) Pseudo cross-section profile ( C4-C4\ ) 60
Figure (4.7 ): An interpretation model and model parameters for sounding Ky33
61
Figure (4.8 ): An interpretation model and model parameters for sounding Ky39
61
Figure (4.9 ): An interpretation model and model parameters for sounding Ky13
61
Figure (4.10 ): An interpretation model and model parameters for sounding Ky16 62
Figure (4.11): An interpretation model and model parameters for sounding Ky22 67
Figure (4.12): An interpretation model and model parameters for sounding Ky51 67
Figure (4.13): An interpretation model and model parameters for sounding Ky50 67
Figure (4.14): An interpretation model and model parameters for sounding Ky49 68
Figure (4.15): An interpretation model and model parameters for sounding Ky37 68
Figure (4.16): An interpretation model and model parameters for sounding Ky46 68
Figure (4.17): An interpretation model and model parameters for sounding Ky44 69
Figure (4.18): An interpretation model and model parameters for sounding Ky45 69
Figure (4.19): An interpretation model and model parameters for sounding Ky43 69
Figure (4.20): An interpretation model and model parameters for sounding Ky41 70
Figure (4.21): An interpretation model and model parameters for sounding Ky30 74
Figure (4.22): An interpretation model and model parameters for sounding Ky24 74
Figure (4.23): An interpretation model and model parameters for sounding Ky28 74
Figure (4.24): An interpretation model and model parameters for sounding Ky56 75
Figure (4.25): An interpretation model and model parameters for sounding Ky1
75
Figure (4.26): An interpretation model and model parameters for sounding Ky3
75
Figure (4.27): An interpretation model and model parameters for sounding Ky8
76
Figure (4.28): An interpretation model and model parameters for sounding Ky27 79
Figure (4.29): An interpretation model and model parameters for sounding Ky7
79
Figure (4.30): An interpretation model and model parameters for sounding Ky54 79
Figure (4.31): An interpretation model and model parameters for sounding Ky2
80
Figure (4.32): An interpretation model and model parameters for sounding Ky6
80
Figure (4.33): An interpretation model and model parameters for sounding Ky66 80
Figure (4.34): An interpretation model and model parameters for sounding Ky65 85
Figure (4.35): An interpretation model and model parameters for sounding Ky64 85
Figure (4.36): An interpretation model and model parameters for sounding Ky63 85
Figure (4.37): An interpretation model and model parameters for sounding Ky62 86
Figure (4.38): An interpretation model and model parameters for sounding Ky61 86
Figure (4.39): An interpretation model and model parameters for sounding Ky60 86
Figure (4.40): An interpretation model and model parameters for sounding Ky59 87
Figure (4.41): An interpretation model and model parameters for sounding Ky58 87
Figure (4.42): An interpretation model and model parameters for sounding Ky57 87
Figure (4.43): An interpretation model and model parameters for sounding Ky8
88
Figure (4.44): An interpretation model and model parameters for sounding Ky42 92
Figure (4.45): An interpretation model and model parameters for sounding Ky4
92
Figure (4.46): An interpretation model and model parameters for sounding Ky16 92
Figure (4.47): An interpretation model and model parameters for sounding Ky14 93
Figure (4.48): An interpretation model and model parameters for sounding Ky21 93
Figure (4.49): An interpretation model and model parameters for sounding Ky17 93
Figure (4.50): An interpretation model and model parameters for sounding Ky6
94
7
Figure (4.51): An interpretation model and model parameters for sounding Ky9
98
Figure (4.52): An interpretation model and model parameters for sounding Ky45 98
Figure (4.53): An interpretation model and model parameters for sounding Ky12 98
Figure (4.54): An interpretation model and model parameters for sounding Ky13 99
Figure (4.55): An interpretation model and model parameters for sounding Ky15 99
Figure (4.56): An interpretation model and model parameters for sounding Ky19 99
Figure (4.57): An interpretation model and model parameters for sounding Ky5 100
Figure (4.58): An interpretation model and model parameters for sounding Ky54 103
Figure (4.59): An interpretation model and model parameters for sounding Ky3 103
Figure (4.60): An interpretation model and model parameters for sounding Ky4 103
Figure (4.61): An interpretation model and model parameters for sounding Ky46 104
Figure (4.62): An interpretation model and model parameters for sounding Ky57 104
Figure (4.63): An interpretation model and model parameters for sounding Ky27 107
Figure (4.64): An interpretation model and model parameters for sounding Ky28 107
Figure (4.65): An interpretation model and model parameters for sounding Ky31 107
Figure (4.66): An interpretation model and model parameters for sounding Ky51 108
Figure (4.67): An interpretation model and model parameters for sounding Ky40 108
Figure (4.68): An interpretation model and model parameters for sounding Ky20 108
Figure ( 4.69 ): Interpreted geoelectrical cross-section for : (a) cross- section profile
( P1-P1\ ), (b) cross- section profile ( P2-P2\), (c) cross- section profile ( P3-P3\) 109
Figure ( 4.69 ): Interpreted geoelectrical cross-section profiles for: (d) cross- section
profile P4-P4\ ), (e) cross section profile ( P5-P5\ )
113
Figure ( 4.70 ): Interpreted geoelectrical cross-section for : (a) cross-section profile
( C1-C1\ ), (b) cross-section profile ( C2-C2\ ), profile, (c) cross- section profile ( C3C3\), (d) cross- section profile( C4-C4\ )
118
8
LIST OF TABLES
Chapter2
Table (2.1): Main electrode arrays types and sub-types
19
Chapter 3
Table ( 3.1 ) :Geographic location of VES
Table ( 3.2 ) :Raw data.
36
38
9
Chapter 1
1. Study area:
This study covers the southern part of Gaza strip, that is a small portion of the coastal
area of Palestine.(Figure 1.1),(Figure1.2).
1.1 Demography of the study area:
The broad population characteristics of Gaza Governorates are strongly influenced by
political developments, which have played a significant role in the growth and
distribution of population in the Governorates.
Today Gaza Governorates have a very going population in comparison to other
countries, 51% of the population is 14 years or younger. As much as 21% of the Gaza
citizens are 4 years or younger. In addition, Gaza govern orates have an average of
nearly 9 persons per house hold. Moreover, they have a higher average number of
children per adult household members in comparison with west bank and East
Jerusalem.
1.2 Topography :
Gaza Strip characterized by several topographic features .
These features are Elongated ridges, depressions, dry streambeds and shifting sand
dunes.
The ridges and depressions generally extend in a NNE–SSW direction, parallel to the
coastline. They are narrow and consist primarily of Kurkar sandstone. In the south,
these features tend to be covered by sand dunes.
Land surface elevations range from mean sea level (MSL) to about 10 meters a above
mean sea level (m ASL). The ridges and depressions show considerable vertical relief,
in some places up to 60m. Surface elevations of individual ridges range between 20m
and 90m above mean sea level (MSL). The major topographic depressions, filled
with alluvial sediments, collect considerable quantities of storm–water. Flooding is
common in Rafah and Gaza City during the wet season.
The parallel, Kurkar ridges have been dissected by Wadi Gaza, the largest surface
water feature in Gaza. It rarely flows due to numerous water diversion and storage
projects upstream in Israel.
10
However, it has historically cut an incised valley with river terraces to the sea. There
are two other wadies in Gaza:
Wadi Silka near KhanYounis ( a fossil river and now a dry wash) and Wadi Halib
near Beit Hanoun (at tributary of the much larger Nahal shiqma – Israeli terminology)
that drains to the sea just north of Gaza.
1.3 Geomorphology :
Gaza Strip is essentially a foreshore plain gradually sloping westwards. The
quaternary rocks are visible as Kurkar ridges go South West – North East. The ridges
have an increasing height towards the east, from 20 to 100m above sea level. Among
these ridges there are 20-40m deep depressions filled with soils. This geomorphologic
shape continues to the west to Sinai Desert, and to north east to Almajdal. Among
different quaternary soil deposits, the sand dunes are of special interest. They are
formed by wind (Eolic), and located along the seashore. Their main distribution is in
the South and the North. Sand is extensively quarried for construction purposes, e.g.
for local use and export to Israel. The quarrying is an encroachment both on the
landscape and the geomorphologic history of Gaza.
1.4 Coastal Geology :
Holocene and Pleistocene deposits in the Gaza terrestrial area are approximately
160m thick and cover the underlying Pliocene sediments. These deposits consist of
marine Kurkar formation. Shell fragments and quartz sands cemented together, and
sometimes calcareous sandstone. Due to its high porosity and permeability the marine
Kurkar forms a good ground water aquifer. Most of the groundwater in the Gaza Strip
is extracted from this layer. The thickness of the marine Kurkar varies between (10100m) showing a tendency to be thicker near the coast.
The continental Kurkar formation varies from friable to very hard, depending on the
degree of cementation,. Alluvial and wind blown sand deposits are found on top of the
(Pleistocene) Kurkar formations and can locally reach a thickness of 25m. The
following types of alluvial deposits can be distinguished:
-
Sand dunes especially in the south, neat Rafah, oriented mainly ENE to WSW.
More to the north, dunes become sporadic and the sand accumulations are
scattered in a zone of 2 to 3 km from the coast,
11
-
Wadi fillings consist of sandy loess and gravel beds, which can reach a
thickness of 10 to 20m.
-
Alluvial and Aeolian deposits are of varying thickness in the northern part
from the Wadi Gaza alluvial deposits that are widely distributed and
dominated by heavy, loamy brown clay.
Figure (1.3,1.4) present a geological cross section of the costal aquifer and
a generalized stratigraphic sequence .
1.5 Coast and sea bed characteristics :
Going from sea to land, the coastal profile can be divided into the seabed, the beach,
the dune face or Kurkar cliffs, and the adjacent body of the dune or cliff plateau.
The coastal profile does not only consist of sand, but locally also erosion–resistant
formations of rock and Kurkar protrude on the seabed, on the beach, and in the cliffs.
Geophysical survey for the Port of Gaza demonstrated the presence of non-erodible
layers at a mean distance of about 3m below the alluvial seabed. Further, a detailed
bathymetric survey of the area where the Gaza Sea Port is planned revealed that
between the shoreline and 10m depth , the seabed is characterized by areas of rock
outcrops and linear features of sand bars (Sogreah, 1996). On the beach and near the
waterline of the Gaza shoreline on many places Kurkar outcrops and rocky ridges can
be seen.
These hard ridges are important coastal features in that they form natural breakwaters
that tend to mitigate an eroding trend. Where those hard layers are covered only by a
relatively thin layer of sand, a retreating coastal profile will gradually consist of an
increasing amount of erosion-resistant surface.
Defining the erodibility and composition of the steep Kurkar cliffs along the Gaza
coastline is another important challenge, which will hopefully be undertaken soon. If
the ridges are attacked by waves and locally collapse, the eroded Kurkar material will
feed the beach with a mixture of very fine to very coarse sediment.
The fines parts will soon be transported to deep water, whereas the coarse particles
will act as armor layer, protecting the freshly exposed Kurkar cliff face during some
time.
12
1.6 Climate :
Gaza Strip has a characteristic semi – arid climate, and is located in a transitional zone
between a temperate Mediterranean climate to the west and north, and the arid Negev
and Sinai deserts to the east and south.
There are two well – defined seasons: the wet season starting in October and
extending through march, and the dry season from April to September. Peak months
for rainfall are December and January.
Annual average rainfall varies considerably from more than 400 millimeters per year
(mm/y) in the north to about 200 mm/y in the south near Rafah.
The average mean daily temperature in Gaza ranges from 26 degrees centigrade (C) in
summer to 12 degrees C in winter.
1.7 Nature Resources :
Even though Gaza consists largely of built up areas and agricultural land, there are
still some remains of nature. With regard to the natural environment, the differences
in annual rainfall within Gaza are important. The southern part is arid to semi–arid.
The northern part of Gaza City has a semi–humid climate.
Geomorphology and distribution of soil types are of importance with regard to the
distribution of nature areas worthy of protection.
1.7.1 Water Resources :
The water balance in the Gaza Strip is much worse than that in any area around. Gaza
Strip depends on groundwater as the main source for the purposes of drinking
domestic, agriculture and for industry. There are severe problems of water shortage as
well as with water quality. In addition, economic development is well short of what
would be necessary to allow for adequate standards of living, and for shorter for what
would be necessary to improve the quality of life. The water situation in Gaza Strip is
desperate from both quality and quantity perspectives. There is no surface water
except immediately following rainfall and the two shallow aquifers that underlie the
Strip, one is fresh and the other is saline, are both being over pumped. The portion of
the coastal Aquifer that underlies the Gaza Strip is particularly sensitive because of
the low rainfall and because it is the only indigenous source of drinking water. Water
13
is pumped from over 2000 wells, primarily for irrigation purposes. The total
withdrawal is estimated at 140 Mm3/ year.
The main source of water in the Gaza Strip is the groundwater from the coastal
aquifer. No exact figures are available on the total ground water abstraction from the
aquifer, due to unlicensed wells and the Israeli kept secret abstraction.
The coastal Aquifer Management Program (CAMP) estimates the total Palestinian
water abstraction at about 127-147 MCM and the Israeli Mekorot abstraction at about
5-8 MCM and the natural groundwater discharge from the aquifer as 10-15 MCM.
These figures make the total abstraction to be 132-155 MCM and the total discharge
from the aquifer as 142-170 MCM, while the estimated total annual replenishment of
the aquifer is estimated 50-55 MCM. Some studies show the deficit to be in the range
of 50-66 MCM/yr. About 98% of the house holds are served with a water supply
network. Households average monthly consumption of water is 31.3 CM/ month with
average daily per capita consumption of 93 liter.
Indeed, even the total existing quotas for agricultural extraction from existing wells
appear to exceed recharge, there are more than 1,500 illegal wells and extractions
beyond quotas. The quotas permit the digging of new wells with high pumping rates
for drinking water.
In addition to the mining of Gaza aquifers, ground water quality in the Gaza Strip is
threatened. The shallow, unconfined nature of the upper fresh aquifer makes it
vulnerable to contamination from all sources. Over–pumping has permitted saline
intrusion, both from the coast and from the depth. Heavy fertilizer use is leading to
high nitrate concentrations and heavy pesticide use to other residues. Therefore,
groundwater quality deterioration is an additional problem emerged due to many
inter–complicated factors. Increase of all chemical pollutants is well established,
nitrates chlorides, fluorides, and others to the degree are much higher than the
recommended standards of the WHO.
1.8 Sand :
The sand resources in Gaza, especially the coastal sand dunes, represent important
environmental values. These dunes traditionally protect the coastal areas against the
sea. The sand dunes have a natural water cleaning capacity. They are the habitat for
flora and fauna. They also represent certain natural landscape values.
14
1.8 Sand :
A land use of Gaza Strip is based on a regional plan developed by the Ministry of
planning and International Co-operation for the West Bank and Gaza strip (MOPIC.
1998).
A agricultural land occupies about 50% of the and surface and is the dominant
economic sector in Gaza Israeli settlements occupy about 15% of the total land area.
The largest settlement is Gush Qatif in the Mawasi area in Southwest Gaza.
Settlements consist primarily of agricultural land, with intensive farming in
greenhouses. Surrounding the settlements, Israeli authorities have established security
zones, which further reduce access to surrounding land.
1.9 Agriculture :
Agricultural land occupies about 170 Km2, which is close to 50% of the total area of
Gaza. Agricultures the largest single sector in the economy and contributes to 32% of
the economic production. This sector employs approximately half of the active labor
force ( = 50000 employees).
Agriculture has passed through stages of expansion and land reduction. The cultivated
area increased from 170 to 198 km2 from 1966-1968.
Ten years later, the cultivated area was reduced to 179 km2 mainly due to the increase
in urban areas from 11% to 19% of the total area of Gaza. Also, the forest areas and
sand dunes were reduced from 32% to 22%. Green Houses are introduced and the
traditional system of irrigation has been replaced by drip and sprinkler irrigation. Also
traditional crops such as citrus are replaced by other crops such as strawberries,
flowers and others.
Agricultural land is mostly in private ownership, registered in the cadastre or owned
by inheritance. Gaza experiences a fragmentation of agriculture land due to the
traditional system of ownership by in inheritance and percolation of land to family
members. 73% of the agricultural land consists of parcels of less than 9 dunums.
1.10 Housing :
The housing conditions in Gaza Governorates can be classified in terms of density,
quality and types of buildings. Densities vary from 1-6 housing unit per dunum
15
(HU/dun) near the city centers, to 1-3 HU/dun in the suburbs. In the camps the density
can reach 9 housing units per dunum. In rural areas housing is either concentrated in
small villages or in scattered settlements with densities of less than 0.5 HU/ dun.
1.11 Industry :
Industrial output in Gaza Governorates contributes to a law 7.5% to the GDP. The
industrial sector employs 14.7% of Gaza’s labor force, in which small scale, privately
owned enterprises, employing 1-8 employees, dominate. The main industrial sub–
sector that have the largest number of employees are: Garment and Textile,
Construction and Building Materials, Metal Products and Food and Beverages.
Industrial production is distributed among: the local market, the west bank and Israeli
market, at 74%, 6.5% and 18.5% respectively.
16
Figure 1.1 : Location map of Gaza strip
17
90000
Deir El Balah
Mediterranean Sea
85000
Khan Younis
Abasan
Rafah
75000
Egypt
80000
90000
Figure 1.2:Location map of the study area
18
Figure 1.3 Geologic Sketch Across Gaza Governorates
19
Figure 1.4 Generalized Stratigraphic Column
20
Chapter 2
Resistivity Survey
21
2 Resistivity Survey
2.1 Introduction:
Electrical resistivity methods were developed in the early 1900, and have been
widely used since 1970. Resistivity methods employ an artificial source of direct
commutated or low frequency alternating current (I). This current is introduced into
the ground by means of two electrodes. The resulting potential distribution (V) on the
ground, mapped by means of two probes, gives information about the electrical
resistivity distribution below the surface.
Resistivity methods have been used in two types of application mainly:
(a) To survey areas for location of subsurface materials with abnormally high
or low resistivities compared to the surroundings.
(b) To estimate depth of subsurface boundaries that separate layers of different
resistivities, and to estimate these resistivity values.
Many authors have recommended that resistivity methods are used routinely in
exploration fields such as geothermal, mining, groundwater, environmental
engineering and archaeological applications.
2.2 Definition and Resistivity Units:
Resistance, true resistivity, and apparent resistivity:
Consider an electrical uniform cube of side length L, through which a current
(I) is passing. The material within the cube resists the current conduction of electricity
through it, and thus a potential drop (V) between opposite faces is observed. The
resulting resistance (R) is proportional to the length (L) of the resistive material and
inversely proportional to the cross section area (A). The constant of proportionality is
the true resistivity (referred by symbol ). Thus:R L/A
R
L
A
(2.1)
Where , the constant of proportionality is known as the electrical resistivity or
electrical specific resistance.
According to Ohm’s Law, the resistance is given by:
22
R 
V
I
(2.2)
Where V is the potential difference across a resistor, and I is the electrical current
through a resistor.
Substituting equation (2.1) in equation (2.2), we get:

V A
I L
(2.3)
The unit of resistivity is the Ohm.meter ( m), and its inverse, the
conductivity (), has units of Siemens/meter (S/m) or mhos/meter (-1 m-1).
The apparent resistivity of a geologic formation (a) is equal to the true
resistivity of a fictitious homogenous and isotropic medium in which, for a given
electrode arrangement and current I, the measured potential difference V is equal to
that for the given inhomogeneous medium Resistivity measurements are usually
carried out with four-electrode arrays consisting of two current and two potential
electrodes. For a better understanding of the resistivity calculation, it is better to
assume, at first, that the current enters an isotropic homogeneous whole space by an
electrode placed at the origin (O) of a three-dimension coordinate system (Fig. 2.1). In
such a medium at a distance (r) from the origin, the current density J at a distance (r)
is:
Jr 
I
4r 2
(2.4)
since the area of the surface is 4r2
Ohm’s law, in general form, can be written as:
Er  J r  
I
4r 2
(2.5)
The potential (V) at a distance (r) from the current electrode is given by the
integration of the electrical field (Er) between (r) and infinity, by the usual definition
of potential, as follows:
23

V   Er dr 
r
I
4r
(2.6)
S
X
O
r
Y
z
Figure (2.1): An electrode at origin O of a co-ordinate system. S is the surface of a
sphere of radius r.
Considering the source electrode at the surface of a half-space, then the
current flows through a hemisphere of radius (r) and the surface area 2r². Hence
equation (2.5) will be reduce to:
Jr 
1
2r 2
(2.7)
and the potential of equation (2.6) to:
V 
I
2r
or   2r
V
I
(2.8)
This equation provides the fundamental relationship for all electrical
prospecting performed at the surface of the earth.
24
In the field four electrode arrays are used generally. For such an array, as in
Figure (2.2), there are two current electrodes AB, or C1C2 and two potential
electrodes MN, or P1P2.
I
V
A
N
B
P2
C2
M
C1
Figure (2.2): Two current and two potential electrodes on the surface of a
homogeneous isotropic earth.
A, B = Current electrodes (or C1, C2).
M, N = Potential electrodes (or P1, P2).
To calculate the potential differences (V) between M and N, the reciprocity
theorem can be used and thus:
A
Potential at M due to source I at A = VM 
I
2 AM
Potential at N due to source I at A = VN 
I
2 AN
A

 I
2 BM
VNB 
 I
2 BN
B
Potential at M due to sink –I at B = VM
Potential at N due to sink –I at B =
25
Total potential at M due to source at A and sink at B is
VMA, B 
I  1
1 



2  AM BM 
Total potential at N due to source at A and sink at B is
V N A, B 
I  1
1 



2  AN BN 
Then, the total potential difference is:
VMNA, B  VMA, B  V NA, B 
I  1
1
1
1 


 

2  AM BM AN BN 
(2.9)
The resistivity of a half-space is then given by rewriting equation (2.9) as:
  2
V
K
I
1
1
1 
 1



Where K = 

 AM BM AN BN 
(2.10)
1
that so called
geometric
factor, which depends on the specific array used.
If the measurements of the resistivity () in equation (2.10) are made over a
semi- infinite homogeneous and isotropic medium, then the value of  will be the true
resistivity of that medium. If the medium is inhomogeneous, then the resistivity
computed from equation (2.10) is called apparent resistivity (a). The apparent
resistivity depends upon the geometry and resistivities of the elements constituting the
given geologic medium and is a function of several variables such as electrode
spacing, geometry of electrode array, true resistivities, layer thicknesses, angles of dip
and an isotropic properties.
2.3 Electrode Arrays:
A variety of electrode arrangements have been proposed. Whitely (1981)
presents a set of 25 electrode arrangements, and comments on the advantages and
disadvantages of each one. Three main types of electrode configuration (Wenner,
26
Schlumberger and Dipole-dipole array) can be considered. Table (2.1) shows the three
main array types and sub-types, and on Figure (2.3) the more common electrode
arrays are shown as well as the equations for the calculation of the apparent resistivity
for each electrode configuration.
Table (2.1): Main electrode arrays types and sub-types.
Wenner arrays
Standard Wenner
Offset Wenner
Lee partitioning array
Tripotential (,  ,and  arrays)
Schlumberger array
Standard Schlumberger
Brant array
Gradient array
Dipole-Dipole arrays
Normal (polar) array
Azimuthal
Radial
Parallel
Perpendicular
Pole-dipole
Equatorial
Square
27
Wenner array ()
C1
P1
a= 2aR
P2
a
Wenner array()
a= 6aR
a
C1
a
C2
P2
a
Wenner ()
P1
a
C1
Schlumberger array

 
2
V C1C 2 / 2  P1P 2 / 2
a  
*
I
P1P 2
P1
a
C1
a= 3aR
C2
P1
a
C2
P2
a
a
P2
C2

2
with C1C 2  5 P1P 2
C1
Dipole-dipole array
a= n ( n+1) (n+2 )
aR
C2
a
P1
P2
na
* C1C2
Current electrodes
* P1P2
Potential electrodes
a
* R is the electrical resistance
Figure (2.3): Electrode configurations used in electrical resistivity surveys and the
corresponding apparent resistivity equations.
2.4 Resistivity Sounding and Horizontal Profiling:
The subsurface materials electrical properties can be explored by sounding,
profiling and imaging techniques. The objective of a sounding survey is to determine
the variation of electrical conductivity with depth, theoretically without any lateral
28
variations, therefore it is important to stress that the Vertical Electrical Sounding
(V.E.S) is only vertical in the above sense.
Briefly:

When a resistivity sounding is carried out, the electrode spacing interval is
changed while the location of the spread center remains fixed.

When a resistivity profile is carried out, the whole array is moved along
lines across the area under investigation with a fixed electrode spacing.
The purpose of profiling is to detect lateral changes in resistivity that
might be caused by a dipping fault, a cavity, and therefore the profile
orientation should be perpendicular to the expected geological strike.
As resistivity sounding survey does not take into account the lateral changes in
the subsurface resistivity, a more accurate way to investigate the subsurface is a twodimensional (2-D) survey. These surveys are normally carried out using a large
number of electrodes (25 or more), connected to a multi-core cable. A laptop
microcomputer together with an electronic switching unit is used to automatically
select the relevant electrodes for each measurement.
The development of software and hardware allows using of 3D surveys. In this
case 2D surveys are carried out along parallel profiles and better picture of the earth is
obtained.
With increasing application of resistivity studies to the environmental time
lapse, 1D surveys have also been proposed. In this case the whole survey is repeated
at different times so that time variations of resistivity are recorded.
2.4.1 Sounding:
An electrical sounding consists on a succession of apparent resistivity
measurements carried out with an increasing electrode separation, while the array
centre and its orientation remains fixed. Figure (2.4) shows how the distance between
the current electrodes is related with the depth to which the current penetrates .
29
Figure (2.4): Proportion of current flowing below depth z ; AB is the current electrode
half-spacing.
Presentation of resistivity sounding field data:
Apparent resistivity sounding data are presented normally on double
logarithmic co-ordinates graphical form. Figure (2.5) shows an example for a
resistivity sounding curve.
30
Figure (2.5): Resistivity sounding curve showing apparent resistivity as a function of
current electrode half-separation (AB/2)
2.5 Interpretation of Electrical Soundings, Profiling, Mapping and
Imaging:
The measured apparent resistivity values are normally plotted on a log-log
graph paper. To interpret the data from such a survey, it is assumed that the
subsurface consists of horizontal layers. That is, the subsurface resistivity changes
with depth only, and not laterally. A horizontally layered earth with no in
homogeneities is a 1-D earth model (Figure 2.6).
The geoelectrical sounding consists on a particular set of readings done at a
specified point, such that the value of K is progressively changed. With Wenner array
the sounding is done by progressively increase the value of “a” by moving all the four
electrodes outwards after each reading. With the Schlumberger array, the sounding
maybe done by moving only the current electrodes, progressively increasing the
distance AB. When AB is very large compared to MN, the potential drop between M
31
and N may be too small to be measured. Hence, it is necessary to increase the distance
between M and N.
The ideal situation shown in Figure (2.6) for 1-D structure is rarely found in
practice. Lateral changes in the subsurface resistivity will cause changes in the
apparent resistivity values that may be misinterpreted as changes with depth in the
subsurface resistivity. Loke (2001) mentioned that there are two main reasons why 1D resistivity sounding surveys are common. The first reason is the lack of proper field
equipment to carry out the more data intensive 2-D and 3-D surveys. The second
reason is the lack of computer interpretation tools to handle the more complex 2-D
and 3-D models. However with late 90´s there have been important hardware and
software developments so that, 2D and 3D surveys are commoner.
The geoelectrical profiling is obtained when an array, with constant geometry,
is used along a line. That is, lateral changes can be surveyed along a particularly
chosen direction.
On other hand, geoelectrical mapping consists on obtaining resistivity readings
over an area with an array with a constant geometry. In this case a resistivity
distribution is obtained over a (X,Y) surface.
A further field arrangement is a pseudosectioning or imaging. In this case a
two-dimensional electrical imaging survey are usually carried out with a large number
of electrodes, connected to a multi-core cable. The field technique involves doing
repeated constant-separation apparent resistivity traverses along the chosen profile,
but the electrode spacings are being incremented at each pass. In this way an apparent
resistivity space section, or pseudosection, is built up, which is then contoured
providing a qualitative picture of the distribution of the subsurface resistivity.
However, where the subsurface is 2D and some control is available, quantitative
interpretation is possible. The selection of configuration and spacing depends on
many factors. For general purposes the Wenner array seems preferable, where
subsurface structures are more easily visualised from inspection of the contoured
sections than from those developed from Dipole-Dipole data, and Wenner apparent
resistivity values are also less affected by near-surface variations. Moreover, in the
case of Wenner array, the tripotential checks can also be made to test measurement
accuracy.
32
In the interpretation of resistivity sounding data, there is a difference between
geological and geoelectrical section. A geological section may show a series of
lithologically defined interfaces that do not necessarily coincide with boundaries
identified electrically. Different lithologies can have the same resistivity values and
thus would form only one electric unit.
C1 P1 P2 C2
1
2

3


1-D model
2-D model
3-D model
Figure (2.6): The three different models used in the resistivity measurement interpretation.
2.5.1 Types of theoretical electrical sounding curves over horizontally
stratified layers:
The interpretation of electrical sounding data requires a large number of
theoretical master curves. Mooney and Wetzel (1956) prepared a set of 2300 curves
for the Wenner array, from which only 15% are three-layer and, the reminder
representing four–layer cases. A set of two-layer curves is also included to complete
the set. La Compagnie Generale de Geophysique (1957) published a set of 480 curves
for the Schlumberger array for two layers resting on an infinite substratum. Orellana
and Mooney (1966) published a set of 25 curves of two–layer models and 76 master
tables and curves for three layer sets, with a total of 712 three–layer cases.
Anonymous (1963a) published 72 sets; each set containing 10 curves, making a total
of 720 curves available for interpretation of three-layer case. Van Dam and
33
Meulenkamp (1969) published a comprehensive set of 3 layer curves for the
Schlumberger array.
Theoretically plotted master curves for four–layer cases are available as “
Paletka ” in Anonymous (1963b), where this set contains 122 sets. The four–layer
curves of Orellana and Mooney (1966) consist of a total of 480 cases distributed in 30
sets. All these of theoretical master curves have been plotted on a double logarithm
graph sheets with a modulus of 62.5 mm.
The form of the curves obtained by sounding over a horizontally stratified
medium is a function of three factors: the resistivity of the layers (1, 2,…n), the
thicknesses (h1, h2, ….hn), and the electrode configuration. If the ground is composed
of a single homogeneous and isotropic layer of infinite thickness (h) and finite
resistivity, then the apparent resistivity curve will be a straight horizontal line whose
ordinate is equal to the true resistivity of the semi-infinite medium.
A brief description for the types of theoretical electrical resistivity curves will
be given bellow.
Two-layer earth model curves:
For two-layer earth model, there are two sets of theoretical master curves;
ascending type, where 2>1, and descending type, where 2<1 (Figure 2.7). These
sets can be used also for the construction and interpretation of multilayer curves.
From Figure (2.7) it seems that the sounding curve begins at small electrode spacing,
with a horizontal segment (a  1). As the electrode spacing is increased, the curves
rises (if it is ascending type), or falls (if it is descending type). At electrode spacing
larger than the first layer thickness, the sounding curve asymptotically approaches to
the horizontal line whose value represents that of the apparent resistivity for the
second layer.
Three-layer earth model Curves:
If the ground is composed by three layer of resistivities 1, 2 and 3
respectively, with thicknesses h1 and h2, the whole set of the three layer sounding
curves can be divided into four groups according to the relation between resistivity
values (Figure 2.8). These groups are:
34
(1) H-type section: 1 > 2 < 3 (referred to Hummel) and known as minimum
type curves.
(2) A-type section: 1 < 2 < 3 (referred to the term anisotropy).
(3) K-type section: 1 < 2 > 3 and known as maximum type curves.
(4) Q-type section: 1 > 2 > 3.
Orellana and Mooney (1966) presented 76 three-layer sets of master tables and curves
including 25 each of H- and K-types, and 13 each of Q- and A-types, with total of 912
three–layer cases.
Four-layer earth model curves:
Orellana and Mooney (1966) published four-layer curves. The curves consist
of a total of 480 cases distributed in 30 sets, while the set of Anonymous (1963b)
contains 122 sets of four layer curves. The curves form of four-layer curves comes
from the combination of the curves of the types H, A, K and Q. Therefore, it is easy to
see that there are only eight types of four-layer curves designated as HA; HK, AA,
AK, KH, KQ, QQ and QH (Fig. 2.9).
35
Figure (2.7) Two-layer ascending and descending type master curves.
36
Figure (2.8): Three-layer type curves.
37
Figure (2.9): Nature of four-layer type curves:. A) HA- and HK-type; B) QHand QQ-type; C) KH- and KQ-type; D). AA- and AK type.
38
Multilayer earth model curves:
If the ground is composed by more than three horizontal layers, then the
geoelectric section is described in terms of the relation between the main types (H, A,
K, and Q). As indicates for four-layer section, there are 8 possible relations between
the resistivities. For a five-layer geoelectrical section there are 16 possible
relationships between the resistivities. Each of these 16 geoelectrical sections may be
described by a combination of three letters. In general, an n- layer section (where n 
3) is described by (n-2) letters.
2.5.2 Elements of Resistivity Sounding Interpretation Process of 1-D
Earth Model:
The aim of geophysical interpretation of the resistivity sounding data is to
determine the thickness and the resistivity of different horizons from the study of the
sounding field curves and then to use these results to propose a geological model for
the study area. The sounding curves can be interpreted qualitatively or quantitatively.
Mooney (1984) summarized the basic resistivity interpretation process in four
steps as follows:
(1) Assume a trial earth model. The assumed model will specify the numerical values
of all the required parameters (resistivities, and thicknesses). By using the
catalogue of pre-calculated theoretical curves the initial choice can be proposed.
The catalogue must be searched for a theoretical curve, which matches the field
curve. The second approach, often used in conjunction with the first, is to base
the trial model with all the available geologic and drilling information.
(2) Compute the theoretical field curve to be expected from the trial model. Using
software computer program helps in this stage.
(3) Compare the theoretical model with the observed field data.
(4) Modify the earth model as necessary to improve the agreement, until the best
possible fit has been achieved. The comparison of the field data and the
adjustment of the trial model must be interpreted with understanding the
relationship between the geoelectrical model parameters and the resistivity
sounding curves. This understanding may be developed easier by studying the
theoretical curves set and by using computer programs. Computer programs can
39
be used to obtain better models by a calculation a wide variety of geoelectrical
models and computing the resulting sounding curves.
40
Chapter 3
Geophysical Methods Application on
study Area
41
Chapter 3
Geophysical Methods Application on study Area
In this research we have must to do an applicative part in the field, but we can’t
because of the political situation of the area. So we used the previous results
which produced by Italian project 1997.
Vertical Electrical sounding (VES) were conducted at 66 sites in the study area
(Figure 3.1).
Field data presented on tables (3.1) , (3.2).
Vertical Electrical sounding measured by applying a current directly into the
ground through a pair of electrodes. A voltage difference measured across a
second electrode pair provides the necessary information to calculate the apparent
earth resistivity.
The depth of investigation is a function of electrodes spacing and geometry.
42
95000

66 64 
63
Mediterranean Sea
Deir El Balah
62

61 60

59 58

57
32

30
 23
85000
26
27
24
28
Khan Younis
29
22

31
51
 40
35
34
33

39

Rafah
20

EGYPT
56 55

36
1
38
Abasan
49
34
37
 11
47 46
44
45 
 9
10 43

13 12  42

41
15

16
14

7

5
54
 2
6
8

19 18
75000
17 21
90000
80000
Figure ( 3.1) : Location map of VES
43
Table ( 3.1 ) :Geographic location of VES
VES
X
Y
Z
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
87350
89400
88000
88000
89750
90000
88600
89600
87800
86850
86400
87000
86000
85500
85100
86500
83750
84600
83700
80100
84500
83500
85550
85150
85700
87000
87100
85950
81700
84800
85100
87100
83800
84300
82800
85500
85550
85250
84250
83350
87800
87600
87350
82400
81900
80900
81000
83100
81800
84000
79750
79100
79100
80300
78000
76200
75750
76750
76750
74000
75200
75150
77950
74000
83100
85700
85350
86150
87100
85720
84400
82700
86200
83300
87900
80500
81500
82000
82350
80700
81850
80000
81750
77250
77650
78000
85
92
82
82
101
100
86
80
75
76
69
58
53
52
52
55
70
58
66
50
66
50
36
36
34
40
80
60
60
33
80
30
65
70
74
83
58
73
50
70
68
60
58
44
VES
X
Y
Z
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
86550
87000
86150
85700
85850
85200
84750
84100
89300
87900
86700
91700
91300
90750
90100
89750
89600
89050
88550
88150
88050
79200
78750
79800
80300
80400
81200
81600
82600
82750
82900
83350
90850
91150
91500
92050
92400
92600
93350
93650
93900
93950
74
72
70
64
64
63
70
70
95
83
71
60
48
37
28
25
23
9
4
1
1
45
Table ( 3.2 ) :Raw data :
AB/2
Ky1
Ky2
Ky3
Ky4
Ky5
Ky6
Ky7
Ky8
Ky9
Ky10
3
4
5
6
8
10
13
16
20
25
30
40
50
60
80
100
130
160
200
250
300
400
500
600
800
1000
1300
1600
2000
14.5
11.2
9.7
8.8
7.7
7.4
7.2
7.7
8.1
9.4
10.6
12.5
14.9
17.7
22.6
25.6
30.4
32.6
33.7
34.4
32
25.9
18.7
24.7
19.3
14.6
12.8
10.6
10.4
9
8.9
9
9.5
10.3
12.5
14.4
16.9
21
25.2
29.2
33
36.7
38.7
39
40
37.6
31
22.5
11.6
54.6
53.1
53.1
45.3
59.2
69.4
71.6
68.6
66.6
61.4
56
52
55
60.2
72.3
80.2
83.5
83.5
80.7
73.5
67.3
53.3
38.4
23.1
9.8
5.1
45.4
51.3
50.5
52.2
56.2
63.6
63.2
63.2
61
64.5
65.3
69
75
80
75
80
75
77
73.4
9.6
7.3
6
4.8
4.5
4.2
4.4
4.9
5.7
7.3
8.3
10
12.3
14.4
18.2
21.4
25.8
28.8
32.4
32.8
31.4
28.1
26.6
24
19
14
11.5
9.3
7.7
6.8
6.2
6.2
6.8
7.9
9.6
11.1
12.8
14.8
16.9
19.5
21.8
23.6
26.4
30.4
36.6
14.2
10.6
8.6
7.9
7.3
7.4
7.6
7.6
8.5
9.6
10.7
14
17.5
19.8
25.2
29.8
31
32.5
34.5
35.2
33.6
29.8
5.9
20.6
14.1
37.4
33.2
25.7
21
15
15
16.3
18.6
21.2
32.8
26.4
30.1
32.6
35.3
41.1
64.6
82
91
99.2
110.4
112.1
115.6
118.4
119.4
119.8
122.8
125.6
129
123.7
122.7
117.9
111.8
94.3
71.2
42.2
26.7
13.9
7.8
4.7
3.4
2.9
56.3
51
49.8
49.6
45.4
59.2
69
78.5
88.5
100.2
112.4
125.8
143
57.5
42.8
24.7
13.9
6.3
46
45.4
41.5
38.2
30.7
22.7
20.4
14.8
10.1
8.9
34.4
32.3
14.4
9.1
4.7
3.5
161.2
165.4
149.2
130.5
105.9
79.9
Ky11
Ky12
Ky13
Ky14
Ky15
Ky16
Ky17
Ky18
Ky19
Ky20
61.7
50.2
42.5
36.9
30.9
31.3
31.5
34
36.8
38.5
40.9
48
52.3
56.3
63.1
71.7
83.2
86.8
83.7
70.5
61.4
42.3
26.5
18.1
7.2
2.6
44.5
34.8
29
23.1
16
16.8
14.7
14
15
16
17.1
51
34
26
20.8
15.3
14.1
14.7
15.3
18.1
19.4
21.5
24
28.3
31.5
34.8
35.4
33.1
30.4
26.8
21.4
17.2
10.3
6.8
4.7
2.4
1.9
18.1
17.2
17.6
17.3
17.1
16.6
15
14.3
54.9
39.1
30.1
22
16.1
13.6
13.7
15.6
16
17.9
19
19.8
19
19.8
20.2
20.3
19.4
18.1
11
7.8
5.6
3.7
2.9
2.3
1.9
1.7
26.4
17.8
13.9
10.4
8.2
48.3
42
35.2
32.7
32.3
35.6
37.7
39.4
41.5
42.6
45.7
47.9
49.2
53
51.6
53.7
45.3
40.2
31.3
51
39.8
35.3
29
26
21.8
16.4
14.9
13.1
11.2
10.6
9
7.8
6.5
5.5
5.4
5.4
5.6
6
6.6
7
7
6.6
4.6
3.5
2.7
1.8
1.5
39.9
34.2
50.1
53.5
63.5
74.8
86.5
101.4
109.3
117.8
125
134.7
137.1
146.4
144
130
123.4
108.2
94
66
23.3
25.9
29.9
33.7
35.7
36.2
34.2
28.2
20.1
10.5
5.9
3.1
1.9
1.3
14
14.3
15
15.9
16.5
17.6
18
16.6
13.2
10.3
7.4
5.9
3.9
3
2.5
2.1
1.9
9.7
10.2
11.1
12.8
14.1
16.3
18
19.5
21.2
21.2
20.9
19.1
15.5
11.3
7
3.8
2.7
2.2
1.9
47
29.7
27.1
26.2
26.9
27.3
27.4
28.8
29.4
31.2
33.5
35.9
38.8
39.5
38
34.6
25.8
17.9
4.6
3.9
3.3
Ky21
Ky22
Ky23
Ky24
Ky25
Ky26
Ky27
Ky28
Ky29
Ky30
46
34.3
30.3
24.7
21.4
20.4
19.7
18.5
16.2
15.9
15
14.8
16.2
17.6
20.9
24.1
28
27
24.9
21.7
18.9
12.5
8.3
5
3.1
2.9
160.1
148.1
135
127.3
122.9
126.4
130.3
132.9
135.1
143.5
143.2
143.2
138.4
126.8
93.3
68.9
52.7
46.1
40.9
37.5
36.6
31.3
21.1
16.6
13.2
10.1
8.5
8.8
9.8
11.1
12.9
13.6
14.6
15.3
15.9
17
18.5
18
17.3
14.6
40.9
40.8
41
40.5
41.4
41.9
43.3
44.8
47.1
50.5
52.5
58.1
62.8
67.1
72.7
73.4
64.3
50.1
33.3
20.8
12.1
8.2
5.3
4.1
34.2
31
28.4
26.2
23.8
21.9
20.2
19.5
18.7
18.8
19.2
22.3
26
27
31.2
33.2
32.2
49.4
40.3
33.6
27.4
21.4
18.8
15.4
13.7
13.8
15.2
17.6
22
26.1
30.4
35.8
39.5
42
41
37.3
31.3
22.4
8.9
184.3
198
211.5
221.4
247.6
255.5
226.7
200.2
170.5
131.1
117.7
112.9
110.3
117.3
136.4
61.6
60.8
61
62.2
68.2
72.4
82.4
99.7
112.7
128.6
140.1
145.3
154.3
168.9
186.6
183.8
173.3
147.3
130
136.8
131.3
128.3
124.3
115.6
119.2
123.3
123.6
122.9
120.4
116
103.5
90
48.6
45.6
44
44.2
41.6
42.5
39.1
38.5
35
30.6
27
22.3
16.8
14.1
13.3
12.7
10.7
9.5
6.7
5.2
4.5
2.8
8.3
48
67
45.6
31.5
54.3
44
36.4
33.3
30.2
26.8
Ky31
Ky32
Ky33
Ky34
Ky35
Ky36
Ky37
Ky38
Ky39
Ky40
27.2
23.4
21
21.5
23.3
26.5
30.7
33.8
36.8
41
44.2
47.2
36.3
32.6
29.5
25.1
23
22
22.1
22.6
22.7
22.4
25.3
27.3
27.6
28.5
27.7
24.2
18.9
14.5
11
9.2
7.1
6
75.1
75.5
75.3
75.5
63
55
46.3
38
29
23.7
22.1
22.4
25.2
28.2
32.6
38.3
46.8
57.6
65.5
82.1
93.4
101.8
112.5
117.2
109.5
92.8
110
109
105
105
96.5
19.3
21.5
22.8
25.8
28.6
30.9
32.8
30.6
26.1
26.2
28.2
31.8
34.5
37.3
41.6
46.7
50.7
50.3
44.6
23
26.3
19.6
16.6
30.7
29.9
21.2
18.2
17.2
17.6
19.4
22
25.8
29.1
32.4
36.1
40
48.2
53.89
57.7
65.7
71.2
73
69.7
63.3
53.8
43.9
26.5
17.5
175.2
160.2
143.2
124.7
103.9
95.7
87.6
80.3
70.6
70.8
67.5
56.5
44.2
36.5
31.2
29
27.2
24.7
22.6
19.8
17.1
13.1
11.2
81.3
85.5
86
83.8
76
69.4
65.5
65.2
65.6
68.6
74.3
83.2
85.6
85.3
86.4
84.2
81.3
74.5
67.8
54.4
46.4
26.9
14.8
55.8
57.8
62.5
66.6
67.8
65.3
55.2
43
34
22.7
38
39.7
43.5
47.4
49.4
53
52
54
46
41
34.2
73.8
60.8
47
35.2
32.5
33.7
39
44.4
55.6
61.7
63
61.8
59.8
55
49.4
39.7
30.2
49
26.9
24.4
23.5
24.1
24.8
27.2
30.8
34.2
39.3
44.3
48.9
52.6
56.8
57.1
54.5
49.4
41.4
36.9
29.4
Ky41
Ky42
Ky43
Ky44
Ky45
Ky46
Ky47
Ky48
Ky49
Ky50
60
58
53
51
49
34
25
20
18
19
20
24
28
33
48
40
42
42
40
35
30
18
10
7
4
38
30
25
20
18
16
33
33
34
34
33
40
40
39
38
39
40
50
54
60
60
60
54
45
36
31
25
15
6
68
70
72
80
90
100
110
120
120
130
130
130
130
130
130
140
120
83
65
45
20
38
45
57
70
100
130
150
160
160
180
190
200
190
180
160
180
140
130
100
68
48
18
10
4.5
2
68
85
100
130
140
150
160
170
180
190
180
170
160
150
140
130
110
90
80
60
58
36
21
48
44
42
38
32
27
25
24
25
28
31
38
42
49
62
78
90
10
100
70
52
28
40
35
33
30
29
28
28
29
30
33
93
44
50
59
70
80
89
92
90
78
64
36
20
12
34
32
32
31
32
32
31
32
30
30
29
30
34
37
43
45
40
36
32
30
20
15
7
38
39
39
40
50
60
72
75
83
80
75
69
61
59
51
51
50
40
39
29
24
9.5
4
17
19
20
25
30
34
39
40
30
26
21
11
7
4
50
Ky51
35
38
40
41
49
50
62
70
83
85
95
100
100
110
94
90
93
78
70
52
40
20
Ky52
Ky53
Ky54
Ky55
25
23
18
16
13
12
13
14
15
17
19
25
29
33
40
45
45
45
40
42
38
30
25
51
Ky56
Ky57
Ky58
Ky59
Ky60
48
37
30
26
23
20
19
18
17
16
15
16
17
17
16
16
18
20
21
23
24
22
18
62
85
100
120
160
180
200
200
190
180
160
155
150
165
160
150
150
145
160
7
7.5
8
8
8.9
9.5
12
14
16
18
19
24
29
32
45
50
59
62
62
55
48
35
23
40
32
27
20
17
14
16
16
17
22
32
39
40
42
49
49
39
29
20
16
9
8.5
12
44
49
42
40
30
28
19
19
18
17
17
18
19
22
21
21
19
18
16
14
9.5
9.6
3.9
Ky61
Ky62
Ky63
Ky64
Ky65
Ky66
32
22
18
12.5
9.5
9.5
9.5
12
13
16
18
20
24
25
23
20
15
13
8.5
4.8
1.2
18
15
14
10
8.9
9
9.5
10
14
18
19
24
27
32
32
32
20
12
11
7.5
4.4
4
40.9
50
60
60
58
47
40
32
26
17
11
8.5
6
6.2
2.6
6.1
5.4
4.2
2.6
2.2
1.6
16
4.9
3.9
3.4
3
3
4
4.5
5
5.5
6.4
7
6.8
7
6.5
5
4.5
3.4
3
1.9
5
5
5
4.5
4.2
4.2
4.5
4.4
5
5.9
7
7.9
8.4
8.4
7.9
8
6.3
6.5
6
6
5.5
5
4.7
4.9
4.3
4.9
5.9
6
7
7.5
7.9
7.8
6
4
1.6
1.2
52
Chapter 4
Interpretation of Apparent Resistivity
Field Data
53
Chapter 4
Interpretation of Apparent Resistivity Field Data
4.1 Introduction and objectives of the chapter:
The aim of the geophysical interpretation of resistivity sounding data is to determine
the thickness and the resistivity of different profiles for the area of study, and to use
these results to obtain a geological model of the area.
We can estimate the number of layers and the relative magnitudes of the resistivities
from the curve shape.
The objectives of this chapter can be summarized as follows:1- To construct pseudo sections to trace any change in resistivity.
2- To construct cross – section to identify the true sequence of beds and
its true thicknesses and depths.
3- To trace any structural features such as fault, low resistivity zones and
to correlate there features with the known geology and structures of the
area deduced from borehole information.
Some of the proposed geoelectrical models have been supported and confirmed by
seismic survey which produced by black hawk project.
4.2 Qualitative Interpretation of Apparent Resistivity cross–sections:
The vertical scale represents the electrode spacing, and doesn’t represent the actual
depth, so the sections followed only show a relation of apparent resistivity with depth
(pseudosection).
Five pseudosection with a NW-SE direction and four pseudosections with NE-SW
direction, were chosen in the study area. The distribution of the pseudosections is
shown in the Figures (4.1.A) (4.1.B). the apparent resistivity values and their
corresponding electrode spacing are inputted in the IPI 2 win program to produce the
pseudosections. These pseudosections are presented in Figures (4.2) (4.3) more details
about these pseudosections is given below.
54
95000
P5  
66 64 
63
Mediterranean Sea
Deir El Balah
62

61 60

59 58

57
P4
P5\
P3
32

P2
30
 23
P1
26
27
24
85000
Khan Younis
29
22

51
34
33

7
56 55


5

36
54
1
38
 2
6
Abasan
3
49

P4\
4
37
 11
47 46
8

44
45 
 9
P3\
10 43

13 12  42

41
15

16
P2\
P1 \
14
31
 40
35
28

39

Rafah
20

19 18
75000
17 21
EGYPT
80000
90000
Figure ( 4.1.A ) : Location map of cross section profile P
55
95000

66 64 
63
Mediterranean Sea
Deir El Balah
62

61 60
C4

59 58

57
32

30
 23
85000
26
27
24
28
Khan Younis
22
29

31
51
 40
35
34
33

39

Rafah
20

C4\
56 55

36
1
38
Abasan
49
34
37
 11
47 46
44
45 
 9
10 43

13 12  42

41
15

16
14

7

C3
5
C2
 2
6
54
8

C1
19 18
75000
EGYPT
17

21
C3\
C2\
C1\
90000
80000
Figure ( 4.1.B ) : Location map of cross section
profile C
56
4.2.1 NorthWest – South East pseudosections:
Five NW–SE pseudosections have been selected to cover the study area. The
pseudosections are presented in Figure (4.2) and their locations are shown in Figure
(4.1.A) these pseudo sections are:
Pseudosection line P1–P1\:
Pseudosection line P1-P1\ (NW – SE) including soundings ky29, ky35, ky40, ky33,
ky39, ky13 and ky16, extends to about 7700m in North-West to South-East direction
in the southern side of the study area (Fig 4.2.a).
In this section we observed two high resistance area, the first one extend between
ky29 and ky35 (about 4500) in NW direction, then the resistivity values decreased at
SE direction in between ky40 and ky33, after that it is start to increased another time
in the second area at ky39.
Lately, the resistivity values decreased until reaching ky16.
In vertical direction of the pseudosection, we see general decreased in resistivity
values with increasing spacing, the apparent resistivity shows a general decrease with
apparent depths.
Lateral change of apparent resistivity can be observed a long this section from ky29
(NE) to ky16 (SE) where the contour line values decreases from 75m to 13.3m for
the larger electrode spacing. A low resistivity zone is observed in between ky13 and
ky16, that may related to a structural features.
Pseudosection P2‫ــ‬P2\:
Pseudosection line P2-P2\ (fig 4.2.b) extend to about 1000m from North-West to
South-East and includes sounding ky22, ky51, ky50, ky49, ky37, ky44, ky45, ky43
and ky41. the pseudosection shows a long resistive area from ky46 to ky45.
surrounded by two conductive zones, one of these zones near to North Western started
to increased in resistivity values begin from Ky49 to ky22. at large spacing we
noticed a horizontal layers. Inspection of pseudosection P2-P2\ makes it possible to
propose a fault between ky37 and ky46 because of the contour lines is parallel and
semi – perpendicular.
57
Pseudosections P3‫ــ‬P3\ :
This pseudosection extends to about 7800m from North-West to South-East, and
includes soundings ky30, ky24, ky28, ky50, ky1, ky3 and ky8 as shown in Figure
(4.2.c).
There are two resistive zones, separated with low values at ky1. one zone take place at
the left of ky1 especially at ky28, and the other sets to the right of ky1, and
concentrated at ky3 to ky8. With increasing electrode spacings. The apparent
resistivity show a general in crease with apparent depth. Lateral change of apparent
resistivity can be observed along this section from ky24 (to the NW) to ky8 (to the
SE), where the contour line values increased from 27.8m to 129m for the larger
electrode spacings. A low resistivity zone is observed in the area and is located
between soundings ky56 and ky3. that may related to a structural accident.
We observed that the contour lines are parallel and semi-perpendicular to the surface
at ky56 and at ky1 to ky3, that may overbalance a presence of two faults at these
places respectively.
Pseudosection P4‫ ــ‬P4\:
Pseudosection P4-P4\ extends to about 5400m from North-West to South-East, and
including soundings ky27, ky7, ky54, ky2 and ky6 as shown in Figure (4.2.d). The
pseudosection shows a large resistive area from ky27 and extends to about 1700m to
the direction south east of the profile. Then the resistivity values started to decrease
until reaching ky6. The section also shows a general decrease in the apparent
resistivity as the electrode spacing increase from 3m to 20m between ky7 to ky6,
then the values of resistivity begin to increase to reaching spacing 400m.
At ky27 as the electrode spacing increase the apparent resistivity values increased.
Fault can be proposed between ky27 and ky7, that may related to extending the ridges
which Gaza Strip include them. This fault is confirm on the semi parallel and semi
perpendicular of contour lines sitting in this area.
58
Pseudosection P5‫ ــ‬P5\ :
Pseudosection P5-P5\ (Fig 4.2.e) includes soundings ky66, ky64, ky63 , ky62, ky61,
ky60, ky59, ky58 and ky57. the section shows two conductive areas. The first one
started from ky66 continued to ky64 with gradually decrease of apparent resistivity
values.
The second area begin from ky63 to ky57 with increasing of apparent resistivity
gradually. A high resistivity values concentrated at ky63, ky60, and ky57.
In vertical direction we observed general decreased in resistivity values as electrode
spacing increase. In between ky63 and ky62 we saw that the apparent resistivity
values decreased with increasing electrode spacing. At ky62 to ky59 we observed that
the apparent resistivity values are increased at approximately spacing 100, and the
contour lines are closed to each other. A semi-perpendicular lines are presented
between ky58 and by 57, that may related to a structural formation As electrode
spacing increase especially from spacing 100 the container lines are parallel to each
other and to the surface. Fault may be proposed left of ky57.
59
P1\
P1
(a) Pseudo cross- section P1-P1\
P2\
P2
(b) Pseudo cross- section P2-P2\
P3\
P3
(c) Pseudo cross- section P3-P3\
Figure ( 4.2): Resistivity pseudo cross-section for ( P1-P1\ ) to ( P3-P3\ ) . (a)
Pseudo cross- section( P1-P1\ ) , (b) Pseudo cross- section ( P2-P2\ ) ,(c) Pseudo crosssection ( P3-P3\ ) .
60
P4\
P4
(d) Pseudo cross- section P4-P4\
P5\
P5
(e) Pseudo cross-section P5-P5\
Figure ( 4.2 ): Resistivity pseudo cross-section for ( P4-P4\ ) to ( P5-P5\ ) .(d)
Pseudo cross- section ( P4-P4\ ), (e) Pseudo cross-section ( P5-P5\ ).
61
4.2.2 North East – South West Pseudosections:
Four pseudosections are selected to cover the study area in this direction. The
pseudosection are presented in Figure (4.3) and their location is shown in Figure (4.1
B).
Pseudosection C1 ‫ ــ‬C1\ :
Pseudosection C1-C1\. Figure (4.3.a) includes sounding ky17, ky21 ky14, ky16, ky42
and ky8. This section contain two resistive areas at the two sides of the section
separated with a conductive zone extends to about 4500m in between ky21 and, ky41,
the apparent resistivity values are in general low in this zone.
As the electrode spacing increase the contour lines are folded as anticline. One of the
resistive area is sitting between ky17 and ky21 and the other is presents at ky41 and
ky8.
In vertical direction in the conductive zone we observed that the apparent resistivity
values decreased as electrode spacing increase.
Pseudosection C2 ‫ ــ‬C2\ :
Pseudosection C2-C2\ (Fig 4.3.b) includes soundings ky19, ky15 ky13, ky12, ky45,
ky9 and ky6. In the middle of this section there is a very resistive zone. This zone
extends to about 4500m horizontally and vertically extends between 3m to 200m.
This zone is surrounded by conductive layers in both sides.
One of this zones have an apparent resistivity values decreases to the SW of the
pseudosection (at ky19). At large electrode spacing we observed a semi-parallel
horizontal contour lines that related to the shape of layers in the natural. Fault can be
proposed between ky12 and ky45 which confirm with our observation of vertical
layers.
Pseudosection C3 ‫ ــ‬C3\ :
Pseudosection C3-C3\ runs in NE – SW direction (Fig. 4.3.c) includes soundings
ky46, ky4, ky54 and ky5. The distance between the successive sounding in larger than
that in the other pseudosections, which may reduce the accuracy of the interpretation.
62
Pseudosection C3-C3\ shows a high resistive area between ky46 to ky4. In another
side there is a conductive area extend between ky4 to ky5. These consequences of
apparent resistivity are also repeated as the electrode spacing increase.
Pseudosection C4 ‫ ــ‬C4\ :
This pseudosection line C4-C4\ (Fig4.3.d), at the bottom of the page including
soundings ky20, ky40, ky51 , ky31 , ky28, ky27 and ky57.
This section shows a large resistive area between ky28 to ky57, this resistive zone
gives an indication to a thick resistive layers at this location.
Another resistive zone is observed between sounding ky40 to ky20. Aconcductive
area separates these two resistive zones. This conductive zone extend to the largest
electrode spacing, and it is reflect a vertical and closed contour lines to each other,
which corresponds to a presence of fault.
63
(a) Pseudo cross-section profile C1-C1\
(b) Pseudo cross-section profile C2-C2 \
(c) Pseudo cross-section profile C3-C3 \
(d) Pseudo cross-section profile C4-C4\
Figure ( 4.3) : Resistivity pseudo cross-section for ( C1-C1\ ) to ( C4-C4\ ).
(a) Pseudo cross- section profile ( C1-C1\ ), (b) Pseudo cross- section profile
( C2-C2\ ), (c) Pseudo cross-section profile ( C3-C3\ ), (d) Pseudo cross-section
profile ( C4-C4\ ) .
64
4.3 Quantitative Interpretation of Apparent Resistivity Field
Data:
4.3.1. Interpretation of sounding curves:
There are sixty–six geoelectrical soundings were carried out in the study area. The
sounding locations and its qualitative interpretations were described in the previous
articles.
More details about quantitative interpretation of the sixty–two of sounding curves are
given below. For all the curve models figures, the X–axis is the electrode spacing (m),
Y-axis is the apparent resistivity ( m), the field values of the apparent are marked by
circles and the curve it self is presented by a black line, the blue curve is the
calculated mode, and the red curve is the theoretical sounding curve.
For the tabulated data, N is the layer number, A is the calculated resistivity (m) , h is
the layer thickness (m), d is the layer depth (m), and alt is the layer altitude (m) above
the man sea level. The error value represents the relative difference between the
theoretical and field curves for the current sounding and its model parameter.
65
Profile P1 ‫ ــ‬P1\ :
Ky29 :
The interpreted geoelectrical model for this sounding is depicted in Figure (4.4) as:
1- As upper most sand soil cover with a resistivity of 195m and 1.78m
thickness.
2- A second layer with a resistivity of 91.5m up to a depth of 3.98m,
that could be clay.
3- A third layer with a resistivity of 220m up to a depth of 11.2m, that
could correspond to sand.
4- A fourth layer with a resistivity of 41.7m up to a depth of 106m, is
believed to be saturated Kurkar.
5- A fifth layer with a resistivity of 1.35m, that may represent the Saqia.
Ky35:
The interpreted geoelectrical model of this sounding is illustrated in Figure (4.5) and
shows:
1- An upper most soil cover with a resistivity of 116m, and 6.46m thickness.
2- A second layer with a resistivity of 5.42m, up to a depth of 3.57 m, that could be
interpreted as clay layer.
3- A third layer with a resistivity of 100m, up to a depth of 102m, is believed to be
Kurkar formation.
4- A fourth layer with a resistivity of 1.02m, that could be correspond to the Saqia.
Ky40:
The interpreted geoelectrical model of this sounding is illustrated in Figure (4.6) and
shows:
1- The first sand soil layer with resistivity of 94.1m, and 4.71m thickness.
2- The second layer with 31.9m resistivity and 4.7m thickness, so it could be clay
layer.
3- The most resistive layer of 111m and with a depth of 113m, it could be Kurkar
formation.
66
4- The fourth layer with resistivity of 1.15m, that could be correspond to Saqia.
Ky33:
The geoelectric model for the sounding ky33 is shown in the Figure (4.7) as follows :
1- An upper most layer with a resistivity of 75.2m up to a depth of 6.13m, that could
be sand layer.
2- A second layer with a resistivity of 16.6m up to a depth of 7.17m, is believed to
be clay.
3- The more depth layer with 66.6m and a resistivity of 100m, that could be Kurkar.
4- A fourth layer with a resistivity of 0.96m that may represent the Saqia.
Ky39:
The geoelectrical model of sounding ky39 is illustrated in the Figure (4.8) and is
shown as:
1- The first layer of sand with a resistivity of 205m, up to a depth of 2.35m.
2- The second layer with a resistivity of 77.8m, up to a depth of 18.2m, and it might
be predict to be clay.
3- The most deeper layer of 158m and a resistivity of 25.8m could be Kurkar.
4- The fourth layer with a resistivity of 5.67m, it reflect the Saqia layer.
Ky 13:
The geoelectrical model of this sounding is illustrated in Figure (4.9) and shows:
1- An upper most layer with a resistivity of 88.6m up to a depth of 1.56m, that could
be soil cover.
2- A second layer with a resistivity of value 12.3m up to a depth of 12.4m, that
represents a clay.
3- A third layer with a resistivity of 54.8m, and 98m of thickness and this make it to
be probable to be saturated Kurkar.
4- A fourth layer with a resistivity of 108m, which could be interpreted as a Saqia.
67
Ky16:
The interpreted geoelectrical model for sounding ky16 illustrates in Figure (4.10) and
shows the following sequence:
1- The first layer of sandy clay with a resistivity of 57.2m, and 1.52m thickness.
2- A second layer have a resistivity of 4.77m, up to depth 4.76m that corresponds to
be clay.
3- A third layer with a resistivity of 31.3m, extending to a depth of 61.3m that could
be saturated Kurkar.
4- A fourth layer with a resistivity of 1.66m, which may be interpreted
as a Saqia.
68
Figure (4.4 ) : An interpretation model and model parameters for sounding Ky29 .
Figure (4.5 ) : An interpretation model and model parameters for sounding Ky35 .
Figure (4.6) : An interpretation model and model parameters for sounding Ky40 .
69
Figure (4.7 ) : An interpretation model and model parameters for sounding Ky33 .
Figure (4.8 ) : An interpretation model and model parameters for sounding Ky39 .
Figure (4.9 ) : An interpretation model and model parameters for sounding Ky13 .
70
Figure (4.10 ) : An interpretation model and model parameters for sounding Ky16.
71
Profile P2 ‫ ــ‬P2\ :
Ky22:
The interpreted geoelectrical model for this sounding is depicted in Figure (4.11) as:
1- An upper most sand layer with a resistivity of 182m and 3.24m thickness.
2- A second layer with a resistivity of 52.5m up to a depth of 5.88m that may be
sandy clay.
3- A third layer with a resistivity of 234m up to a depth of 88.6m, that could
correspond to unsaturated layer of Kurkar.
4- A fourth layer with a resistivity of 0.631m, that represent the Saqia formation.
Ky51:
The interpreted geoelectrical model for this sounding is shown in Figure (4.12) as :
1- An upper most soil cover with a resistivity of 33.9m, and 1.89m thickness.
2- A second layer with a resistivity of 43.7m, up to a depth of 5.21m, that could be
sandy clay layer.
3- A third layer with a resistivity of 148m, up to a depth of 98.9m, that could be
interpreted as unsaturated kurkar layer.
4- A fourth layer with a resistivity of 1.0m, that could be Saqia layer.
Ky50:
The interpreted geoelectrical model for this sounding is shown in Figure (4.13) as:
1- An upper most clay layer with a resistivity of 35.8m, and 4.59m thickness.
2- A second layer with a resistivity of 296m up to a depth of 4.12m that could be
interpreted as sand layer.
3- A third layer with a resistivity of 31.3m up to a depth of 20.8m, is believed to be
clay.
4- A fourth layer with a resistivity of 107m, with a thickness of 63.8m that could be
correspond to unsaturated Kurkar layer.
5- A fifth layer with a resistivity of 0.832m that could be the Saqia.
72
Ky49:
The proposed geoelectrical model for ky49 is illustrated in Figure (4.14) and shows
the following sequences:
1- The topmost layer have a resistivity of 33.1m with a thickness of 10.7m, so it
could be sandy clay layer.
2- The next layer with a resistivity of 20.4m and a thickness of 20.9m, that could
reflect clay layer.
3- A third layer with a resistivity of 117m up to a depth of 53.5m, that may
represent saturated Kurkar.
4- A less resistive layer with a resistivity of 0.933m, reflect the Saqia.
Ky37:
The interpreted geoelectrical model for sounding ky37 illustrates in Figure (4.15) and
shows the following sequence:
1- The upper most soil layer with a resistivity of 45.8m up to a depth of
1.51m.
2- The second layer with a resistivity of 20.1m up to a depth of 11m,
which may be clay.
3- The third layer with a resistivity of 104m, and a depth of 74.1m, so it
may be the unsaturated kurkar layer.
4- The lowest layer with a resistivity of 1.23m, that may represent the
Saqia.
Ky46:
The interpreted geoelectrical model for this sounding is depicted in Figure (4.16) as:
1- An upper most soil cover with a resistivity of 33.9m, up to a depth of 1.2m.
2- A second layer with a resistivity of 282m, and thickness of 11.1m, so it may be
reflect to sand layer .
3- A third layer with a resistivity of 13.2m, and 108m of thickness, is believed to be
Kurkar layer.
4- A fourth layer with a resistivity of 2.75m that may represent the Saqia.
73
Ky44:
The proposed geoelectric model is illustrated in Figure (4.17) as follows:
1- An upper most clay soil layer with a resistivity of 21.4m up to a
depth of 1.02m.
2- A second layer with a resistivity of 229m, up to a depth of 4.6m that
could correspond to sand layer.
3- A third layer with a resistivity of 132m, up to a depth of 120m, is
believed to be unsaturated Kurkar.
4- A fourth layer with a resistivity of 1.03m, that may represent the
Saqia.
Ky45:
The interpreted geoelectrical model for this sounding is shown in Figure (4.18) as
follows:
1- An upper most soil cover with a resistivity of 11.1m up to a depth of 0.734m.
2- A second layer with a high resistivity of 409m, up to a depth of 9.98m this high
resistivity layer could correspond to a sand layer.
3- A third layer with a resistivity of 162m up to a depth of 108m, that could
correspond to unsaturated Kurkar.
4- A fourth layer with a resistivity of 1.67m that may reflect a Saqia.
Ky43:
The geoelectrical model of this sounding is illustrated in Figure (4.19 ) and shows:
1- An upper most layer with a resistivity of 29.5m, up to a depth of
2.72m, that could be clay soil layer.
2- A second layer with a resistivity of value 39.8m up to a depth of
22.4m, that represent a clay layer.
3- A third layer with a resistivity of 112m, up to depth of 64m, that
could correspond to Kurkar.
4- A fourth layer with a resistivity of 1.74m, that may represent the
Saqia.
74
Ky41 :
The geoelectrical model of this sounding is illustrated in Figure (4.20) as follows:
1- An upper most sandy soil cover with a resistivity of 61.7m, up to a depth of
4.47m.
2- A second layer with a resistivity of value 11.5m, up to depth of 14.2m, that
represent a clay layer .
3- A third layer with a resistivity of 102m, up to depth of 68.5m, that could
correspond to unsaturated Kurkar.
4- A fourth layer with a resistivity of 2.5m, that may reflect a Saqia .
75
Figure (4.11) : An interpretation model and model parameters for sounding Ky22.
Figure (4.12) : An interpretation model and model parameters for sounding Ky51.
Figure (4.13) : An interpretation model and model parameters for sounding Ky50.
76
Figure (4.14) : An interpretation model and model parameters for sounding Ky49.
Figure (4.15) : An interpretation model and model parameters for sounding Ky37.
Figure (4.16) : An interpretation model and model parameters for sounding Ky46.
77
Figure (4.17) : An interpretation model and model parameters for sounding Ky44.
Figure (4.18) : An interpretation model and model parameters for sounding Ky45.
Figure (4.19) : An interpretation model and model parameters for sounding Ky43.
78
Figure (4.20) : An interpretation model and model parameters for sounding Ky41.
79
Profile P3 ‫ ــ‬P3\ :
Ky30:
The interpreted geoelectrical model of this sounding is illustrated in Figure (4.21), and
shows:
1- An upper most soil cover with 45.5m value of resistivity and 13.2m thickness.
2- A second layer with a resistivity of 12.8m, and up to a depth of 101m, that this
layer could be Hamra (clay) .
3- A third layer with a resistivity value of 1.76m, that may represent the Saqia.
Ky24:
The geoelectrical model of sounding ky24 is illustrated in the Figure (4.22) and is
shown as:
1- The first layer of day with a resistivity of 40.2m, up to a depth of
16.6m.
2- The second layer with a resistivity of 126m, up to a depth of 54.2m,
and it might be predict to be Kurkar.
3- The most deeper layer of 1.62m value of resistivity, represents the
Saqia.
Ky28:
The proposed geoelectrical model is shown in Figure (4.23) as follows:
1- Clay layer of 6.92m thickness, and with a resistivity of 58.5m .
2- Resistive layer with a resistivity of 252m and a thickness of 88.6m,
that could be interpreted as sand layer.
3- A third layer that is the substratum, with a resistivity of 1.01m, and
that could correspond to the Saqia layer.
80
Ky56:
The interpreted geoelectrical model for this sounding is shown in Figure (4.24) as:
1- An upper most sandy soil cover with a resistivity of 111m, and 0.816m thickness.
2- A second layer with a resistivity of 43.4m, up to a depth of 1.79m, that could be
interpreted as clay layer.
3- A third layer with a resistivity of 15.7m, up to a depth of 72.6m, is believed to be
Hamra (clay).
4- A fourth layer with a 113m resistivity value, with a thickness of 49.9m that
could be correspond to unsaturated Kurkar layer.
5- A fifth layer with a resistivity of 0.96m that could be the Saqia.
Ky1:
The geoelectrical model for this sounding was interpreted as follows in Figure (4.25)
as:
1- An upper most soil cover with a resistivity of 21.5m, and 1.7m thickness.
2- A second layer have a resistivity of 5.89m, up to a depth of 14.9m, that
corresponds to clay layer.
3- A third layer with a resistivity of 102m, extending to a depth of 83.4m, that could
be Kurkar layer.
4- A fourth layer with a resistivity of 0.741m, which may be interpreted as the
Saqia.
Ky3:
The proposed geoelectrical model for ky3 is illustrated in Figure (4.26) and shows the
following sequences:
1- The topmost layer have a resistivity of 50.1m with a thickness of 4.41m, so it
could be soil cover.
2- The next layer is may be sand that, it have a resistivity of 371.2m and a thickness
of 1.74m.
3- A third layer with a resistivity of 22.4m, up to a depth of 14.3m, that may
represent Hamra (clay).
81
4- A fourth layer with a resistivity of 170m, and 99.8m thickness, this layer could be
reflect the Kurkar layer.
5- The last layer with a resistivity of 1.66m, which could be interpreted as a Saqia
layer.
Ky8:
The proposed geoelectrical model for ky8 is illustrated in Figure (4.27) and shows the
following sequences:
1- The topmost layer have a resistivity of 44.9m with a thickness of 3.43m, so it
could be soil cover.
2- The next layer with a resistivity of 139m, and thickness of 5.798m so it may be
sand.
3- The third layer with a resistivity of 18.7m, up to a depth of 10.6m, that may
represent clay (Hamra).
4- The more resistive layer with a resistivity of 166m, with a thickness of 88.5m, so
it could be Kurkar layer.
5- Finally, The substratum layer with a resistivity of 2.11m, that may represents the
Saqia.
82
Figure (4.21) : An interpretation model and model parameters for sounding Ky30.
Figure (4.22) : An interpretation model and model parameters for sounding Ky24.
Figure (4.23) : An interpretation model and model parameters for sounding Ky28.
83
Figure (4.24) : An interpretation model and model parameters for sounding Ky56.
Figure (4.25) : An interpretation model and model parameters for sounding Ky1.
Figure (4.26) : An interpretation model and model parameters for sounding Ky3.
84
Figure (4.27) : An interpretation model and model parameters for sounding Ky8.
85
Profile P4 ‫ ــ‬P4\ :
Ky27:
The interpreted geoelectrical model is illustrated in Figure (4.28) as follows:
1- An upper most layer of sandy soil cover with a resistivity of 122m, up to a depth
of 1.2m.
2- A second layer with a high resistivity of 316m up to a depth of 5.88m, this layer
suitable to be sand.
3- A third layer with a resistivity of 100m, up to a depth of 65.4m, is could be
reflect to Kurkar Formation.
4-A fourth layer with a resistivity of 0.474m, which could be interpreted as a Saqia.
Ky7:
The interpreted geoelectrical model of this sounding is illustrated in Figure(4.29)and
shows:
1- An upper most layer with a resistivity of 20.5m up to a depth of
1.5m, that could be soil layer.
2- A second layer with 6.2m resistivity value and 15.4m thickness, so it
could be clay layer.
3- A more depth layer with 10.2m and a resistivity of 136m, that could
be Kurkar Formation.
4- A fourth layer with a resistivity of 1.17m, that may represent the
Saqia Formation.
Ky54 :
The interpreted geoelectrical model of sounding ky54 is illustrated in Figure (4.30)
and shows:
1- The first layer of soil with a resistivity of 31.8m, up to depth of 2.02m.
2- The second layer with a resistivity of 9.13m, up to depth of 11.8m, and it might
be predict to be sand.
3- The most deeper layer of 96.9m and a resistivity of 100m, that could be Kurkar
Formation.
4- The fourth with a resistivity of 2.04m, it reflect the Saqia formation.
86
Ky2:
The geoelectrical model of this sounding is illustrated in the Figure (4.31) and shows
as:
1- An upper most layer with a resistivity of 38.8m, up to depth of 1.66m
that could be soil layer.
2- A second layer with a resistivity of value 8.47m, up to depth of
26.5m, that represents a clay layer.
3- A third layer with a resistivity of 148m, and 101m thickness and this
make it to be probable to be unsaturated Kurkar Formation.
4- A fourth layer with a resistivity of 1.95m, which could be interpreted
as Saqia Formation.
Ky6:
The geoelectrical model of this sounding is illustrated in the Figure (4.32) and shows
as:
1- A first layer of clay soil with a resistivity of 9.27m, and 1.5m
thickness.
2- A second layer with a resistivity of 4.98m, up to depth of 5.93m, that
represents clay layer.
3- A third layer with a resistivity of 53.5m, and 147m thickness, that
corresponds to unsaturated Kurkar Formation.
4- A fourth layer with a resistivity of 4.9m, that could be Saqia
Formation.
87
Figure (4.28) : An interpretation model and model parameters for sounding Ky27.
Figure (4.29) : An interpretation model and model parameters for sounding Ky7.
Figure (4.30) : An interpretation model and model parameters for sounding Ky54.
88
Figure (4.31) : An interpretation model and model parameters for sounding Ky2.
Figure (4.32) : An interpretation model and model parameters for sounding Ky6.
89
Profile P5 ‫ ــ‬P5\ :
Ky66:
The interpreted geoelectrical model of this sounding is depicted in Figure (4.33) as:
1- An upper most clay soil cover with a resistivity of 6.41m, and 6.52m
thickness.
2- A second layer with a resistivity of 1.13m, up to a depth of 2.51m,
that may be clay layer.
3- A third layer with a resistivity of 15.3m, up to a depth of 38m, that
could correspond to saturated Kurkar Formation.
4- A fourth layer with a resistivity value of 0.283m, that represent the
Saqia Formation.
Ky65:
The interpreted geoelectrical model of this sounding is shown in Figure (4.34) as:
1- An upper most clay soil cover with a resistivity of 4.99m, and 5.54m
thickness.
2- A second layer with a resistivity of 1.03m, up to a depth of 2.27m,
that could be clay layer.
3- A third layer with a resistivity of 19.5m, and a thickness of 38.4m, is
believed to be saturated Kurkar Formation.
4- A fourth layer with a resistivity of 0.542m, that represent the Saqia
Formation.
Ky64:
The interpreted geoelectrical model of this sounding is shown in Figure (4.35) as:
1- An upper most soil cover with a resistivity of 21.1m, and 1.47m
thickness.
2- A second layer with a resistivity of 0.752m, up to a depth of 1.79m,
that, could be clay layer.
3- A third layer with a resistivity of 12m, up to a depth of 40.1m, that
could be saturated Kurkar Formation.
4- A fourth layer with a resistivity 0.96m, that could be interpreted as
Saqia Formation.
90
Ky63:
The interpreted model of this sounding is depicted in Figure (4.36) as:
1- An upper most soil cover with a resistivity of 27.3m and 1.41m
thickness.
2- A second layer with a resistivity of 257m, up to a depth of 1.54m,
that could be sand layer.
3- A third layer with a resistivity of 6.92m, up to a depth of 72.9m, that
could be saturated Kurkar Formation.
4- A fourth layer with a resistivity of 1.26m, that could be interpreted as
Saqia.
Ky62:
The interpreted geoelectrical model of this sounding is shown in Figure (4.37) as:
1- An upper most soil cover with a resistivity of 23.4m and 2.09m of
thickness.
2- A second layer with a resistivity of 3.27m, up to a depth of 2.59m,
that may represent the clay layer.
3- A third layer with a resistivity of 43.7m, up to a depth of 51.6m, so it
believed to be saturated Kurkar Formation.
4- A fourth layer with a resistivity of 1.02m, that could be Saqia
Formation.
Ky61:
The interpreted geoelectrical model of this sounding is shown in Figure (4.38) as:
1- A first layer with a resistivity of 49.6m, and 1.79m of thickness, that
could be soil layer.
2- A second layer with a resistivity of 3.89m, and 3.71m of thickness, so
it may be reflect to clay layer.
3- A third layer with a resistivity of 38m, and a thickness of 44.6m, that
could be saturated Kurkar.
4- A fourth layer with a resistivity of 0.933m, that may represent the
Saqia Formation.
91
Ky60:
The interpreted geoelectrical model for this sounding is shown in Figure (4.39) as:
1- A first layer with a resistivity of 64.6m, and 2.69m of thickness, that
could be sandy soil cover.
2- A second layer with a resistivity of 15.8m, up to a depth of 34.5m,
that may represent the clay.
3- A third layer with a resistivity of 8.91m, up to a depth of 25.9m, that
could be Kurkar Formation.
4- A fourth layer with a resistivity of 1.5m, that could be interpreted as
Saqia.
Ky59:
The interpreted geoelectrical model of this sounding is shown in Figure (4.40) as:
1- An upper most sandy soil cover with a resistivity of 51.6m, and
2.02m of thickness.
2- A second layer with a resistivity of 9.55m up to a depth of 6.69m,
that could be clay layer.
3- A third layer with a resistivity of 115m, up to depth of 38.1m, that
could be unsaturated Kurkar.
4- A fourth layer with a resistivity of 1.23m, that could be Saqia
Formation.
Ky58:
The interpreted geoelectrical model of this sounding is shown in Figure (4.41) as:
1- An upper most clay soil layer with a resistivity of 6.93m, and 6.76m
of thickness.
2- A second layer with a resistivity of 30.2m, up to a depth of 9.84m,
that could be clay layer.
3- A third layer with a resistivity of 186m, up to a depth of 62.8m, that
may represent the unsaturated Kurkar.
4- A fourth layer with a resistivity of 0.891m, that could be interpreted
as Saqia Formation.
92
Ky57:
The interpreted model of this sounding is depicted in Figure (4.42) as:
1- The first layer with a resistivity of 36.5m and 2.09m thickness, that
could be soil cover.
2- The second layer have a resistivity of 646m, up to depth of 1.07m,
that corresponds to sand layer.
3- The third layer with a resistivity of 195m, extending to a depth of
97.9m, that could be unsaturated Kurkar.
4- The fourth layer with a resistivity of 5.25m, which may be
interpreted as Saqia.
93
Figure (4.33) : An interpretation model and model parameters for sounding Ky66.
Figure (4.34) : An interpretation model and model parameters for sounding Ky65.
Figure (4.35) : An interpretation model and model parameters for sounding Ky64.
94
Figure (4.36) : An interpretation model and model parameters for sounding Ky63.
Figure (4.37) : An interpretation model and model parameters for sounding Ky62.
Figure (4.38) : An interpretation model and model parameters for sounding Ky61.
95
Figure (4.39) : An interpretation model and model parameters for sounding Ky60.
Figure (4.40) : An interpretation model and model parameters for sounding Ky59.
Figure (4.41) : An interpretation model and model parameters for sounding Ky58.
96
Figure (4.42) : An interpretation model and model parameters for sounding Ky57.
97
Profile C1 ‫ ــ‬C1\ :
Ky8:
The proposed geoelectrical model for ky8 is illustrated in Figure (4.43) and shows the
following sequences :
1- The topmost layer have a resistivity of 44.9m with a thickness of
3.43m, so, it could be sand soil cover.
2- The next layer with a resistivity of 139m and a thickness of 5.79m,
so it may be sand layer.
3- The third layer with a resistivity of 18.7m, up to a depth of 10.6m,
that may represents clay layer.
4- The more resistive layer with a resistivity of 166m, with a thickness
of 88.5 m, so, it could be Kurkar Formation.
5- Finally, The substratum layer with a resistivity of 2.11m, that may
represents the Saqia Formation.
Ky42:
The geoelectrical model for this sounding was interpreted as follows in Figure (4.44):
1- A topmost layer with a resistivity of 46.9m, up to a depth of 2.08m,
that represent the soil cover.
2- The second layer with a resistivity of 12.4m up to a depth of 13.8m,
which may be clay layer.
3- The third layer with a resistivity of 100m, and a thickness of 57m, so
it may be Kurkar Formation.
4- The lowest layer with a resistivity of 2.05m, that may represent
Saqia.
Ky41:
The geoelectrical model of sounding ky41 is show the following sequence as shown
in Figure (4.45):
1- An upper most soil cover with a resistivity of 61.7m and a depth of
4.47m.
98
2- A second layer with a resistivity of 11.5m up to a depth of 14.1m, so
it could be clay layer.
3- A third layer with a resistivity of 102m and 68.5m thickness, that
could correspond to Kurkar.
4- A fourth layer with a resistivity of 2.5m, which could be interpreted
as Saqia.
Ky16:
The interpreted geoelectrical model for sounding ky16 illustrates in Figure (4.46) and
shows the following sequence:
1- A first layer of soil with a resistivity of 57.2m and 1.52m thickness.
2- A second layer have a resistivity of 4.77m up to a depth of 4.76m,
that corresponds to clay layer.
3- A third layer with a resistivity of 31.3m, extending to a depth of
61.3m, that could be saturated Kurkar.
4- A fourth layer with a resistivity of 1.66m which may be interpreted
as Saqia Formation.
Ky14:
The geoelectrical model of this sounding is illustrated in Figure (4.47) and shows:
1- An upper most soil layer with a resistivity of 18m, up to a depth of
7.18 m.
2- A second layer with a resistivity of 8.28m up to a depth of 9.04m,
which may reflect a clay layer.
3- A third layer with a resistivity of 28.8m up to a depth of 44m, that
could correspond to saturated Kurkar or Hamra.
4- A fourth layer with a resistivity of 2.05m, and we expected it as
Saqia.
99
Ky21:
The geoelectrical model of sounding ky21 is show the following sequence as shown
in Figure (4.48) :
1- An upper most sand soil cove with a resistivity of 55.9m and a depth
of 2.02 m.
2- A second layer with a resistivity of 14.9m up to a depth of 40.3m, so
it could be clay layer.
3- A third layer with a resistivity of 97.4m and 39.5m thickness, that
could correspond to Kurkar Formation.
4- A fourth layer with a resistivity of 2.38m, which could be interpreted
as Saqia.
Ky17:
This curve in the Figure (4.49) was interpreted as:
1- An upper most sand soil cover layer with a resistivity of 67.6m and
a thickness of 1.57m.
2- A second layer with a resistivity of 22.6m up to a depth of 5.36m,
that may correspond to the clay layer.
3- A third layer which more resistive with a resistivity of 67.9m, and
85.2m of thickness and this make it to be probable to be Kurkar
Formation.
4- A fourth layer with a resistivity of 0.4m that may correspond to be
Saqia.
100
Figure (4.43) : An interpretation model and model parameters for sounding Ky8.
Figure (4.44) : An interpretation model and model parameters for sounding Ky42.
Figure (4.45) : An interpretation model and model parameters for sounding Ky41.
101
Figure (4.46) : An interpretation model and model parameters for sounding Ky16.
Figure (4.47) : An interpretation model and model parameters for sounding Ky14.
Figure (4.48) : An interpretation model and model parameters for sounding Ky21.
102
Figure (4.49) : An interpretation model and model parameters for sounding Ky17.
103
Profile C2 ‫ ــ‬C2\ :
Ky58:
The interpreted geoelectrical model of this sounding is shown in Figure (4.50) as:
1-An upper most clayey soil layer with a resistivity of 9.27m and 1.5m
of thickness.
2-A second layer with a resistivity of 4.98m up to a depth of 5.93m,that
could be clay layer.
3-A third layer with a resistivity of 53.5m up to a depth of 147m, that
may represent the Kurkar.
4-A fourth layer with a resistivity of 4.9m, that could be interpreted as
Saqia Formation.
Ky9:
The proposed geoelectrical model for sounding ky9, depicted in Figure (4.51) shows:
1- An upper most layer with a resistivity value of 52.6m and 1.5m
thickness, that may could be soil layer.
2- A second layer with a resistivity of 136m up to a depth of 107m. this
layer reflect a Kurkar Formation.
3- A third layer with a resistivity of 2.9m that may reflect the Saqia.
Ky45:
The interpreted geoelectrical model for this sounding is shown in Figure (4.52) as
follows:
1- An upper most clayey soil cover with a resistivity of 11.1m up to a
depth of 0.734m.
2- A second layer with a high resistivity of 409m up to a depth of
9.98m, this high resistivity layer could correspond to a sand layer.
3- A third layer with a resistivity of 162m up to a depth of 108m, that
could correspond to Kurkar Formation.
4- A fourth layer with a resistivity of 1.67m that may reflect Saqia
Formation.
104
Ky12:
The geoelectrical model of this sanding is illustrated in Figure (4.53) and shows:
1- An upper most sand soil cover with resistivity of 59.2m up to a
depth of 2.15m.
2- A second layer with a resistivity of value of 10.7m up to a depth of
13.6m, that may correspond to the clay layer.
3- A third layer with a resistivity of 91.4m and 48m of thickness and
this make it to be probable to be Kurkar layer.
4- A fourth layer with a resistivity of 1.02m, which could be interpreted
as Saqia Formation.
Ky13:
The geoelectrical model of this sounding is illustrated in Figure (4.54) and shows:
1- An upper most layer with a resistivity of 87.7m up to a depth of
1.56m that could be sand soil cover.
2- A second layer with a resistivity of value 12.3m, up to a depth of
12.4m, that represents a clay.
3- A third layer with a resistivity of 54.8m and 98m of thickness and
this make it to be probable to be Kurkar Formation.
4- A fourth layer with a resistivity of 1.8m, which could be interpreted
as Saqia.
Ky15:
The interpreted geoelectrical model for this sounding is shown in Figure (4.55) as
follows:
1- An upper most layer with a resistivity of 77.8m and a depth of
1.92m, that could be sand soil cover.
2- A second layer with a resistivity of 9.56m, up to a depth of 7.27m,
which may reflect clay layer.
3- A third layer with a resistivity of 28.9m, extending to a depth of
70.1m that could be saturated Kurkar or Hamra.
105
4- A fourth layer with a resistivity of 2.14m, which may be interpreted
as a Saqia.
Ky19:
The interpreted geoelectrical model for this sounding is shown in Figure (4.56) and
shows:
1- A topmost layer of soil with a resistivity of 34.4m and 2.81m
thickness.
2- A second layer with a resistivity of 11m up to a depth of 15.9m, that
corresponds to be clay layer.
3- A third layer with a resistivity of 2.52m, up to a depth of 28.8m, that
could be clay.
4- A fourth conductive layer with a resistivity of 39.6m, up to a depth
of 32.3m, that could be saturated Kurkar or Hamra.
5- A fifth layer with a resistivity of 1.17m, that corresponds to Saqia.
106
Figure (4.50) : An interpretation model and model parameters for sounding Ky6.
Figure (4.51) : An interpretation model and model parameters for sounding Ky9.
Figure (4.52) : An interpretation model and model parameters for sounding Ky45.
107
Figure (4.53) : An interpretation model and model parameters for sounding Ky12.
Figure (4.54) : An interpretation model and model parameters for sounding Ky13.
Figure (4.55) : An interpretation model and model parameters for sounding Ky15.
108
Figure (4.56) : An interpretation model and model parameters for sounding Ky19.
109
Profile C3 ‫ ــ‬C3\ :
Ky5:
The geoelectrical model of this sounding is illustrated in Figure (4.57) and shows:
5- An upper most layer with a resistivity of 15.8m up to a depth of
1.49m that could be clayey soil layer.
6- A second layer with a resistivity of value 3.53m, up to a depth of
11.9m, that represents a clay.
7- A third layer with a resistivity of 87.2m and 103m of thickness and
this make it to be probable to be Kurkar Formation.
8- A fourth layer with a resistivity of 8.63m, which could be interpreted
as Saqia.
Ky54:
The geoelectrical model of this sounding is illustrated in Figure (4.58) and shows:
1- An upper most layer with a resistivity of 31.8m up to a depth of 2.02m, that could
be soil cover.
2- A second layer with a resistivity of value 9.13m up to a depth of 11.8m, that
represents a clay.
3- A third layer with a resistivity of 100m, and 96.9m of thickness and this make it
to be probable to be Kurkar.
4- A fourth layer with a resistivity of 2.04m, which could be interpreted as a Saqia.
Ky3:
The proposed geoelectrical model for ky3 is illustrated in Figure (4.59) and shows the
following sequences:
1- The topmost layer have a resistivity of 50.1m, with a thickness of
4.41m, so it could be sand soil cover.
2- The next layer is may be sand, that it have a resistivity of 371m, and
thickness of 1.74m.
3- A third layer with a resistivity of 22.4m, up to a depth of 14.3m, that
may represent Clay layer.
110
4- A fourth layer with a resistivity of 170m, and 99.8m thickness, this
layer could be reflect to unsaturated Kurkar.
5- The last layer with a resistivity of 1.66m, which could be interpreted
as Saqia Formation.
Ky4 :
The interpreted geoelectrical model for this sounding is depicted in Figure (4.60) as:
1- An upper most soil cover with a resistivity of 44.5m, up to a depth of
3.96m.
2- A second layer with a resistivity of 503m, and thickness of 0.649m,
this layer could be reflect to sand layer.
3- A third layer with a resistivity of 37.8m, up to a depth of 8.04m, that
could be clay layer.
4- A fourth layer with a resistivity of 97.7m and 130m of thickness, is
believed to be Kurkar formation.
5- A fifth layer with a resistivity of 0.393m, that may represent the
Saqia.
Ky46:
The geoelectrical model of this sounding is illustrated in Figure (4.61) and shows:
1- An upper most layer with a resistivity of 33.9m up to a depth of 1.2m, that could
be soil cover.
2- A second layer with a resistivity of value 282m up to a depth of 11.1m, that
represents a sand layer .
3- A third layer with a resistivity of 132m, and 108m of thickness and this make it
to be probable to be Kurkar.
4- A fourth layer with a resistivity of 2.75m, which could be interpreted as a Saqia.
111
Figure (4.57) : An interpretation model and model parameters for sounding Ky5.
Figure (4.58) : An interpretation model and model parameters for sounding Ky54.
Figure (4.59) : An interpretation model and model parameters for sounding Ky3.
112
Figure (4.60) : An interpretation model and model parameters for sounding Ky4.
Figure (4.61) : An interpretation model and model parameters for sounding Ky46.
113
Profile C4 ‫ ــ‬C4\ :
Ky57:
The proposed geoelectrical model is illustrated in Figure (4.62) as follows:
1- An uppermost soil layer with a resistivity 36.5m up to a depth of 2.09 m .
2- A second layer with a resistivity of 646m up to a depth of 1.07m, that could
correspond to sand layer .
3- A third layer with a resistivity of 195m, up to a depth of 97.9m, is believed to be
Kurkar Formation .
4- A fourth layer with a resistivity of 5.25m, that may represent the Saqia .
Ky27:
The interpreted geoelectrical model is illustrated in Figure (4.63) as follows:
1- An upper most layer of sand soil cover with a resistivity of 122m, up to a depth
of 1.2m .
2- A second layer with a high resistivity of 316m up to a depth of 5.88m, this layer
suitable to be sand .
3- A third layer with a resistivity of 100m up to a depth of 65.4m, is could be reflect
to Kurkar Formation .
4- Fourth layer with a resistivity of 0.474m, which could be interpreted as a Saqia .
Ky28 :
The proposed geoelectrical model is shown in Figure (4.64) as follows :
1- Sand layer of 6.92m thickness, and with a resistivity of 58.5m .
2- A conductive layer with a resistivity of 252m and a thickness of
88.6m, that could be interpreted as unsaturated Kurkar .
3- A third layer that is the substratum, with a resistivity of 1.01m, and
that could correspond to the Saqia layer .
Ky31 :
The proposed geoelectrical model is shown in Figure (4.65) as :
1- An uppermost layer of clay soil with a resistivity of 21.3m, up to a depth of
8.48m .
114
2- A second layer with a resistivity of 100m up to a depth of 74m, this layer suitable
to be Kurkar Formation .
3- A third layer with a resistivity of 4.88m, that could correspond to the Saqia layer.
Ky51 :
The interpreted geoelectrical model for this sounding is shown in Figure (4.66) as :
1- An upper most soil cover with are a resistivity of 33.9m and 1.89m thickness .
2- A second layer with a resistivity of 43.7m up to a depth of 5.21m, that could be
sand layer .
3- A third layer with a resistivity of 148m up to a depth of 98.7m, that could be
interpreted as Kurkar layer .
4- A fourth layer with a resistivity of 1m that could be the Saqia layer .
Ky40 :
The interpreted geoelectrical model for this sounding is shown in Figure (4.67) as :
1- An upper most sand layer with a resistivity of 94.1m and 4.71m thickness .
2- A second layer with a resistivity of 31.9m up to a depth of 4.7m, that could be
clay layer .
3- A third layer with resistivity of 111m up to a depth of 113m, that could be
interpreted as Kurkar Formation .
4- A fourth layer with resistivity of 1.15m, that could be the Saqia .
Ky20 :
The interpreted geoelectrical model for this sounding Figure (4.68) shows :
1- An upper most layer with a resistivity of 31.9m and 2.9m thickness, that could be
soil cover .
2- A second layer with a resistivity of 176m, up to a depth of 99.5m, that could be
Kurkar Formation .
3- A third layer with a resistivity of 1.5m, that could be Saqia layer .
115
Figure (4.62) : An interpretation model and model parameters for sounding Ky57.
Figure (4.63) : An interpretation model and model parameters for sounding Ky27.
Figure (4.64) : An interpretation model and model parameters for sounding Ky28.
116
Figure (4.65) : An interpretation model and model parameters for sounding Ky31.
Figure (4.66) : An interpretation model and model parameters for sounding Ky51.
Figure (4.67) : An interpretation model and model parameters for sounding Ky40.
117
Figure (4.68) : An interpretation model and model parameters for sounding Ky20.
118
4.3.2 Geoelectrical Cross sections interpretation :
Five NW–SE cross–sections were carried out in the study area and another four NE–
SW cross–sections . Its locations are shown in Figure (4.1.a,b) .
The cross–sections for the five NW–SE and four NE–SW cross sections were
constructed and shown in Figure (4.67) and Figure (4.68) taking the topography of the
area into account .
More details about cross–sections are given bellow :
4.3.2.1 North Wes–South East cross section :
Cross Section Profile P1 ‫ ــ‬P1\ :
The resistivity interpretation for cross section profile P1-P1\ is shown in Figure (
4.69a ) . The interpreted geoelectrical model shows that the first sand layer from this
sounding has resistivities varies from NW to SE, where as Ky29 has the highest value
of 195Ωm decreases to 57Ωm in Ky16 .
But we observed that Ky39 has high value of resistivity (205Ωm) and that may be
related to the natural of soil in this area.
This differences of resistivity value related to heterogeneous of surface layer.
The geoelectrical model also shows that the second layer is sand layer and include
extraneous small clay lenses.
The third layer represent the Kurkar layer which its resistivities value vary, and so
thickness values(66-150m) , these resistivity differences related to presence of aquifer
in Kurkar rocks that the salinity of ground water change from one place to another.
The last layer represent the Saqia formation which mainly consists of evaporations,
limestone, conglomerates and marl, which causes the depression of resistivity that
increased in places where sea water intrusion occur. Borehole KH /13, between Ky29
and Ky35 shows layers of light brown calcareous sand stone with Brown sandy marl.
Cross Section Profile P2 ‫ ــ‬P2\ :
This cross section is carried out to the right of cross section profile P1-P1\, and is
parallel to it exactly. The interpreted model is shown in Figure (4.69) .
119
The model shows that the upper most layer has different resistivities and thicknesses,
from sounding to sounding .
In fact, the heterogeneous structure of the soil is related to the differences in soil
texture, grain size and water saturation .
This is what interpreted the being of lower resistivity value (11m) in sounding ky45,
while the higher resistivity value is (182m) at ky22 .
The geoelectric model also shows that the second layer has two conductive zones, the
first one at sounding ky50 with small thickness and resistivity value of 296m .
The second conductive zone extend from ky46 to ky45 with resistivity value extended
from 2.29m to 409m .
The third layer which believed to represent the Kurkar layer with resistivity in the
range of 234–102m . The maximum thickness for this layer at ky44 is about 120m .
The lowest layer represents Saqia Formation which is very conductive layer with
resistivity values from 2.5 to 0.6m .
Bore hole L/43 near ky22 in this area indicate the presence of consequences layers of
sand, clay, and Kurkar .
Cross Section Profile P3 ‫ ــ‬P3\ :
This section was carried out to the right of cross sectionofile P2-P2\, and is roughly
parallel to it. The interpreted geoelectrical model is depicted in Figure (4.69 c) . The
interpreted model shows low resistivity values for the upper most cover of soil (21 to
58m), except at sounding ky56 where its resistivity value is 111m with very small
thickness.
Under this cover at ky56 to ky1 we can see small extraneous lenses which have
different thickness and resistivity values .
Kurkar layer has –as usual– different resistivities value from sounding to sounding,
the lower resistivity value ky30 with 12m, this depression in resistance could be
related to the sea water intrusion, or in another case because of presence of high
salinity ground water .
The last layer represent Saqia Formation which characterized by low values of
resistivity .
In this section we observed –at ky56– vertical layer in Kurkar and that may
correspond to faulted area .
120
Borehole Kh/1 near sounding ky28, shows 15m of clay overlying a very thick sand
stone layer . This may explain the increase in the resistivity values westwards .
Cross Section Profile P4 ‫ ــ‬P4\ :
Cross section profile P4-P4\ was carried out to the right of cross section prfile P3-P3\ .
It is include ky27, ky7, ky54, ky2 and ky6 and its geoelectrical model is shown in
Figure (4.69 d) .
The first layer is very thin with average thickness of 1.5m and low resistivity value
(less than 38m) except at sounding ky27 which have 122m . This layer overlays
another conductive layer with resistivity values less than 10m and thickness
between 26m to 5m .
In this layer we have resistance zone at ky27 with 316m, this differential resistivity
may be related to the effects of the fault which we talked about it lately .
Under this layer we have Kurkar layer followed by Saqia Formation, we observed that
the thickness of Kurkar bed increased in the direction from North–West to South–East
in specific length then it began to depressed another time . This is what we observed it
in all cross sections .
Cross Section Profile P5‫ ــ‬P5\ :
All cross sections that we talked about them are located in Khan-Yunis, but cross
section profile P5-P5
\
is located in Der El–Balah and we see that is very complex
than the others .
In this section Figure (4.69 e) we observed general increasing in resistivity and
thickness values in the direction from North-West to South-East .
At the surface of this section we found that the layer which close to the sea have a
lowest resistivity values (0.7m), that may reflect to its saturation with sea water .
This value of resistivities are increased in the direction of South-East .
The Kurkar layer indicate gradient lateral resistivity change from 15m to 185m,
and so that in values of thickness .
Lastly, Saqia layer, we observed it at the lower part of the cross section, and it
characterized by small values of resistivity (1m) .
121
P1\
P1
(a) Cross- section profile P1-P1\
P2\
P2
(b) Cross- section profile P2-P2\
P3\
P3
(c) Cross- section profile P3-P3\
Figure ( 4.69 ): Interpreted geoelectrical cross-section for : (a) cross- section profile
) P1-P1\ ), (b) cross- section profile ( P2-P2\), (c) cross- section profile ( P3-P3\).
122
P4\
P4
(d) Cross- section profile P4-P4\
P5\
P5
(e) Cross section profile P5-P5\
Figure ( 4.69 ): Interpreted geoelectrical cross-section profiles for : (d) cross- section
profile P4-P4\ ), (e) cross section profile ( P5-P5\ ) .
123
4.3.2.2 NE–SW Cross section:
Cross Section Profile C1 ‫ ــ‬C1\:
Cross section profile C1-C1\ was carried out in order to study the resistivity
distribution a long the profile .
Section locations are shown in Figure (4.1.B) , and the interpreted geoelectrical model
is shown in Figure (4.70a) .
This cross section consists of sounding ky8, ky42, ky16, ky14, ky21 and ky17, with
total length of about 8000m . the model shows an upper most layer with different
resistivity values and thicknesses from sounding to sounding . This difference is due
to the heterorganic of soil as we mention before .
A conductive layer is found under lay the soil cover with resistivity tanging between
4m and 22m with different layer depths. The maximum interpreted depth for this
layer is found close to ky21 and approximately 42.3m . This depth is decreases to a
value of 6.2m at ky16 .
The third layer represent the Kurkar layer which have a conductive zone from
sounding ky14 to ky16 with a resistivity values 28m and 31.3m respectively .
The rest of this layer characterized by high resistivity extended between 166m and
67.9m . This difference related to being the Kurkar layer saturated with ground
water in Gaza Strip as we talked about before . So the resistivities value affected with
distribution of ground water and its salinity .
The deeper layer represent Saqia Formation, which is very conductive layer and it’s
resistivity value about 1m .
Cross Section Profile C2 ‫ ــ‬C2\ :
Cross section profile C2-C2\ was carried out to the left of cross section profile C1-C1\
and is roughly parallel to it .
The interpreted geoelectrical model is depicted in Figure (4.70b) . The interpreted
model shows different resistivity values for the upper most cover ranging between
9.2m and 87.7m .
The interpreted uppermost soil cover thickness in the range of 0.7 to 2.8m, this layer
over lay another layer with low resistivity value (13m) except at sounding ky45
which have a resistivity of 409m (very high value) .
124
The third layer have a resistive zone extended a bout 3800m at sounding ky12 to ky9,
that surrounding by a conductive zones . This layer represent Kurkar layer which
characterized by presence of ground water, that make the resistivity values depressed .
The last layer represents Saqia Formation with resistivity values from 1m to 4.9m.
Cross Section Profile C3 ‫ ــ‬C3\ :
Cross section profile C3-C3\ is located to the left of cross section profile C2-C2\, and
includes sounding ky46, ky4, ky54 and ky5 . Its geoelectrical model is shown in
Figure (4.70 c) .
The model shows four layers, that the first and second layers are have different
resistivity values and thicknesses at the length of profile .
We observed that the resistivity is more than 200m up to 3000m, then it is began to
decreased because of presence of clay lence at ky5 and ky54 .
The third layer is correspond to Kurkar rocks (87–170m) as we move to ky5 .
The last layer represents Saqia Formation which un saturated with water that reflect
its relatively height of resistivity value (8m) .
Cross Section Profile C4 ‫ ــ‬C4\ :
Cross section profile C4-C4\ was carried out in order to study the resistivity
distribution a long the S-W orientation .
The interpreted geoelectrical model is on figure (4.70d) . This cross–section consists
of soundings ky57, ky27, ky28, ky31, ky51, ky40 and ky20 with total length of about
8000m .
The model shows an upper most cover with variables values of resistivity as we
discussed previously (heterogenic soil) .
The second layer shown at ky57, ky27 with high resistivity values (606–316m), and
a move conductive zone at ky51 and ky40 .
A third layer represent the Kurkar which reflect the highest resistivity values (100195m) . But with different layer depths from sounding to sounding .
A lower resistivity layer is assumed underneath the Kurkar layer and it is reflect the
Saqia Formation, with resistivity values ranging from 5-0.4m . Fault is proposed at
sounding ky28 .
125
In this section there are an apparent ridge can be seen in the geological map .
Bore hole KH/1 to the left of sounding ky28 indicates a 15m of clay layer and about
64m of sand stone layer, that may explain the high resistivity values .
126
C1\
C1
(a) Cross- section profile C1-C1\
C2\
C2
(b) Cross- section profile C2-C2\
C3\
C3
(c) Cross- section profile C3-C3\
C4\
C4
(d) cross- section profile C4-C4\
Figure ( 4.70 ) : Interpreted geoelectrical cross-section for : (a) cross-section profile
( C1-C1\ ), (b) cross-section profile ( C2-C2\ ), profile, (c) cross- section profile ( C3C3\ ), (d) cross- section profile( C4-C4\ ) .
127
Chapter 5
Conclusion
128
Conclusion
From the previous discussion based on the quantitative and qualitative interpretation
of field resistivity data, it can be concluded:
1- The geological model of Gaza Strip Especially in the study area is
consist of three layers as below:
a- High resistive sand layer.
b- Kurkar layer, that have variable resistivity values,
because the kurkar formation is represent the aquifer of
the area, which consists of interbedded sand and clay
lenses. When these strata contain fresh or saline water
in lithology this is an important factor affecting
apparent resistivity. Therefore, in the Kurkar Formation
resistivity boundaries do not always coincide with
lithologic ones.
c- Saqia Formation which represents a consistent boundary
of low resistivity. This low resistivity is likely due to
high clay content, high concentration salts or both.
2- There are an extraneous lenses of clay distributed between sand and
Kurkar layer, and it have a low resistivity values. These lenses of clay
are called Hamra which is a red clay soil.
3- A structural formation such as faults and folds (Ridges) are suggested
for the study area. Some of these structures are shown on the geology
map of the study area, while others are suggested as results of the
geophysical data interpretation.
4- Contamination of some zones from the study area by the sea water
intrusion, especially closed to the sea are also presented and proposed
as interpreted from geoelectrical interpretation .
5- More geophysical investigations are need for the area. Detailed seismic
studies are proposed to obtain more information for the subsurface
geological model for Gaza Strip.
129
References
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