Table 1 Seismic data acquisition: equipment and parameters
Recorder 48 channel EG G seismograph, model ES-2401X
Ž .
Energy source Dynasource truck mounted vacuum accelerated heavy weight drop
Ž .
Receivers—single geophones 10 Hz vertical
Receiver spacing 2.5 m
Ž .
Shot spacing 2.5 m every station
Ž .
Shot location Near 1st receiver off-end geometry
Minimum offset 1 m
Maximum fold 24
Record length 0.5 s
Time sampling interval 0.5 ms
Analog band-pass filters 70–250 Hz
provide better vertical resolution and accuracy Ž
. of interpretation Goldman et al., 1994 , both
shallow Geonics EM47 and deep EM37 systems were applied in the western part of the line.
For interpretation of the TDEM data, the following approach was applied. First, the inter-
pretational model consisting of a minimum pos- sible number of layers was used. After compar-
ing with the seismic results, additional layers were included in the initial model according to
the seismic interpretation. Such an approach led to a significant improvement of the interpreta-
tional results.
2. Hydrogeological background
The Coastal Plain aquifer of Israel extends along the Mediterranean shore line from the
Gaza Strip in the south to the Mount Carmel in
Fig. 4. Examples of field records from line GI-0082.
V. Shti
Õ elman,
M. Goldman
r Journal
of Applied
Geophysics
44 2000
197 –
215 202
Fig. 5. Seismic section along line GI-0082. Every forth trace is displayed; the trace spacing is 5.0 m.
V. Shti
Õ elman,
M. Goldman
r Journal
of Applied
Geophysics
44 2000
197 –
215
203 Fig. 6. Seismic section in the eastern part of line GI-0082. Every trace is displayed; the trace spacing is 1.25 m.
V. Shti
Õ elman,
M. Goldman
r Journal
of Applied
Geophysics
44 2000
197 –
215 204
Fig. 7. Seismic section in the western part of line GI-0082. Every trace is displayed; the trace spacing is 1.25 m.
the north, reaching the width of 10–15 km eastward. The aquifer consists of the Quaternary
sequence of marine and continental deposits composed predominantly of calcareous sand-
Ž .
stone the Kurkar unit resting on an erosional contact. The sequence starts with the Calabrian
regional regression which terminates the Saqiye marine regime. The accumulated succession of
sediments which follows bears evidence of sev- eral cycles of transgressions and regressions of
the sea. With each cycle, deposition environ- ment shifted from west to east and back. The
lithologic variability observed in the Quaternary sequence reflects different types of sediments
characteristic of a certain environment: calcare- ous sandstone, sandy limestone, sand, clay, silt,
conglomerate and loam. In the west, the aquifer consists of marine deposits, while in the east,
the deposits are of continental origin. Calcare- ous sandstones are generally porous and hydro-
logically conductive and considered aquifers, whereas clays are impermeable and act as
aquicludes. In the places where the clays are thick and extensive enough, they divide the
aquifer into distinct subunits. The aquifer rests on impermeable black shales and clays of the
Saqiye group of Pliocene–Miocene age. The coastal aquifer is replenished by rain
precipitation during the winter months. Ground- water flows westward, toward the sea. Usually,
the groundwater level rises from west to east with a gradient of about 1 m per 1 km. Dis-
charge of the aquifer is in the form of seepage along the seawaterrfreshwater interface. In cer-
tain areas, over-exploitation of the aquifer has caused inland seawater encroachment to more
than 1 km from the sea shore.
A number of observation wells are located at Ž
the investigated site in the Nitzanim area Figs. .
Ž 1 and 2 . Three of the wells 12r0, 12rA and
. 12r1 penetrate the entire aquifer down to the
Saqiye group which is about 160 m deep in this Ž
area. In the western part of the area wells 12r0 .
and 12rA marine sediments are penetrated,
Ž .
whereas in the eastern part well 12r1 conti- nental sediments were encountered. In Fig. 2,
various Kurkar subaquifers encountered in the wells are designated by capital K with corre-
sponding indices.
According to hydrological data, the water table level in the area is about 2–3 m above the
Ž .
mean sea level MSL . The sea water penetrates into the aquifer up to about 1.0 km from the
coastal line.
Fig. 8. Seismic section along line GI-0083. Every forth trace is displayed; the trace spacing is 5.0 m.
A schematic W–E hydrogeological section across the investigated area is represented in
Fig. 3.
3. Seismic survey
