Recharge systems for protecting and enhancing groundwate

TOPIC 7
Arid zones water management / Sustainability of managing recharge systems 871
H
H
0.10
0.09
0.08
0.07
0.06
o
/ 0.05
0.04
0.03
0.02
0.01
Matching point
Type curve
H : Residual
drawdown
Field data curve
t = 5 min.
–1
o< = 10
2
T = ((rc) / t) X 1
2 = ((1.65) / 5) X 1
T = 784 m 2/day
S = 2 2 (rc) / (rs) X o<
2 2 –1
= ((1.65) / (1.85)) X 10
S = 0.080
)
B 1
10,
w
U
F (
0
10
3 0
1 2
1
10
10 10 10
10 4
10 10
m 10 0 )
5
T = ( Q / 4 Π SW ) . F(Uw, B) S = (4 Tt / (rw) ) . U
= (0.2 / 4 X 3.14 X 0.1) X 6.2
2 4
/ (1.575) x = ( 4 X 0.016 X 200 (5x10)
= 23.68 m /day
S = 1.03 x 10 –5
10 2 3 4 5 6 7
- 1
10
wdownsw(
D r a
10 - 2
Field data
Type curve
Matching point
Time (t) (min.)
10- 2 - 1
10 100 10 1
10 2 103
Time (t) min.
Figure 4. Analysis of pumping test data of El Gahelia dug
well using slug test (Papadopulos et al., 1973)
1 -
10
2
10 10 10
1 / U
10 10 10
Figure 5. Analysis of pumping test data
of Frokeit well (Papadopulos’ method).
Hydrogeologic conditions of Nubia sandstone aquifer
Nubia sandstone aquifer has a tremendous importance in the area. It covers the northwestern part of the investigated
area. Nubia sandstone rests directly on basement rocks. It is composed of fine to coarse sandstone intercalated
with clay. The thickness ranges between 100 m up to 500 m (Aglan, 2001). It is detected as a water-bearing
in Wadi Abraq, Abu Saafa and Wadi EL Dif. Five representative water points were selected in the study area. The
groundwater occurs under confined conditions (Abraq spring) and semi- confined conditions (drilled wells).
Rainfall and flash floods on the sandstone plateau and the surrounding fractured basement rocks are considered to
be the main sources of groundwater replenishment. Depth to water varies from 8.17 m to 21.75 m from the ground
surface. On the other hand, the water level ranges between + 248 m and + 281 m (Fig. 6, Table 1).
The hydraulic parameters of Nubian sandstone aquifer
Elewa (2000) mentioned that, the aquifer sediments reflect a wide range of transmissivity (from 2.72 m 2 /day to
72.4 m 2 /day)). This could be attributed to the lateral facies change as well as the impact of the structural setting. To
confirm the obtained results, a trial was carried out by the author using raw data of pumping tests of El Dif well
(GARPAD, 1996), using Jacob straight line method (1963). The obtained value of the transmissivity is comparable
to the previous data (Fig. 7).
Ab u Saafa- b
Abu Saafa - c
)
(
ti on
l
300
280
260
240
220
200
180
m
160
a 140
e v E 120
100
80
60
40
20
0.0
-20
W.T.
SW
Abu Saafa - a
a
-
i q
t a
i r E
B
l w
e
l i
h
e
a
G
a
L
E
D'
4 8 12 16 20 24 28 32 km
Legend
Sand
Quaternary
Gravel
Sandstone Nubian
Sandy clay Sandstone
Basement rocks
Suggested fault
0.0 5 10 15 20 25 km
H. Scale
-40 -20 0 20 40 60 km
V. Scale
Figure 6. Hydogeological cross section ( D–D' )
from southwest to northeast Abu Saafa-El Gahelia area
3.5
3
)
( m
2.5
n s
2
o w
1.5
D r awd
1
0.5
0.0
1
∆s = 1.2 m
Q = 480 m3 / day
T = 73.31 m 2 / day
10
T = 2.3 Q / (4π∆S)
100
Time t (min)
1000
Figure 7. Analysis of pumping test data
of Bir El Dif
10000
10 – 16 June 2005, Berlin ■ 5th International Symposium ■ AQUIFER RECHARGE ■ ISMAR 2005