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Groundwater modeling study central Dhofar, Oman
Thomas Mller1, Gerhard Strauch1
1Helmholtz Centre for Environmental ResearchUFZ, Department of Hydrogeology, Leipzig
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HEADLINE ARIAL FETT 30pt
Subline Arial Roman 30ptStudy Area
study
area
Dhofar
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Study Area
boreholeDAWKAH Town/ Village
main Wadi channels
no DEM
surface water divide
Digital Elevation Model (DEM) of the SRTM Data (Shuttle Radar Topography Mission; USGS 2006)
100-200m
1800 m
Elevation
0 50 100 km
main roads
Study Area
boreholeDAWKAH Town/ Village
main Wadi channels
no DEM
surface water divide
Digital Elevation Model (DEM) of the SRTM Data (Shuttle Radar Topography Mission; USGS 2006)
100-200m
1800 m
Elevation
0 50 100 km
main roads
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Study goals
Goal I: Understanding the hydrogeological systemarid area and scarce data
Goal II: Quantification of the water budget components
precise determination of groundwater resources, recharge and
safe yield
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Climate and Rainfall- considerable variations of climatic conditions between Salalah plain,
- main weather systems: Frontal System, Cyclones, MonsoonDhofar Mountains and Najd
Salalah plain Dhofar MountainsNajd
Salalah plain
Dhofar MountainsNajd
100 mm/yr
300 mm/yr
70 mm/yr
40 mm/yr
0 100 km
S N
- average temperature: 6.1C to 44.6C, grand mean 26,2C
- high ET rates
- rainfall amount low and irregular, average 49mm/yr
Monsoon
Lower Umm Er Radhuma
Upper Umm Er Radhuma
RUS
Dammam
Salalah plain Dhofar MountainsNajd
Salalah plain
Dhofar MountainsNajd
100 mm/yr
300 mm/yr
70 mm/yr
40 mm/yr
0 100 km
S N
- average temperature: 6.1C to 44.6C, grand mean 26,2C
- high ET rates
- rainfall amount low and irregular, average 49mm/yr
Monsoon
Lower Umm Er Radhuma
Upper Umm Er Radhuma
RUS
Dammam
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Climate and Rainfall > Groundwater Recharge
Arabian
Sea
0
250
500
750
[masl]
0 8000 16000 24000 32000 40000 48000 56000 64000 [m]
recharge
amount ?
increasing
spring discharge
2 to 5 weeks
after the monsoon
Monsoon
two recharge mechanism
1) Dhofar Mountains - Monsoon 2) interior Najd Cyclones, Frontal Systems
- direct recharge - causing large short term floods
Cyclonic Storms
recharge?
1) present day recharge in
the Dhofar Mountains:
3 to 9 Mm/year
2) perched aquifers or
infiltration to the deeper ground?
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southern Dhofar
0.00
50.00
100.00
150.00
200.00
250.00
14 Nov 1984 11 Aug 1987 07 Mai 1990 31 Jan 1993 28 Okt 1995 24 Jul 1998 19 Apr 2001 14 Jan 2004 10 Okt 2006
Spring Garsis [elevation 110 m a.ms.l.]
date of observation
discahrgeinl/s
0.00
50.00
100.00
150.00
200.00
250.00
14 Nov 1984 11 Aug 1987 07 Mai 1990 31 Jan 1993 28 Okt 1995 24 Jul 1998 19 Apr 2001 14 Jan 2004 10 Okt 2006
Spring Garsis [elevation 110 m a.ms.l.]
date of observation
discahrgeinl/s
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southern Dhofar
106
108
110
112
114
116
118
25-Mai-79 14-Nov-84 07-Mai-90 28-Okt-95 19-Apr-01 10-Okt-06 01-Apr-12
date of observation
GW-levelm
a.m.s.l.
GW-monitoring point [elevation 132 m a.m.s.l.] 200 m upstream to Ayn Garsis
highest GW-levels in August/ September
106
108
110
112
114
116
118
25-Mai-79 14-Nov-84 07-Mai-90 28-Okt-95 19-Apr-01 10-Okt-06 01-Apr-12
date of observation
GW-levelm
a.m.s.l.
GW-monitoring point [elevation 132 m a.m.s.l.] 200 m upstream to Ayn Garsis
highest GW-levels in August/ September
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Najd
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
11.08.1987 07.05.1990 31.01.1993 28.10.1995 24.07.1998 19.04.2001 14.01.2004 10.10.2006 06.07.2009
560
561
562
563
564
565
566
date of observation
wadidischarge[m/d]
GW
le
velma.m.s.l.
Wadi station Ghadun
monitoring well Aqu A
Wadi Flow and Groundwater level approximately 60 km north of swd
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
11.08.1987 07.05.1990 31.01.1993 28.10.1995 24.07.1998 19.04.2001 14.01.2004 10.10.2006 06.07.2009
560
561
562
563
564
565
566
date of observation
wadidischarge[m/d]
GW
le
velma.m.s.l.
Wadi station Ghadun
monitoring well Aqu A
Wadi Flow and Groundwater level approximately 60 km north of swd
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Najd
0
10
20
30
40
50
60
70
80
31. Jan 93 28. Okt 95 24. Jul 98 19. Apr 01 14. Jan 04 10. Okt 06 06. Jul 09
0.00E+00
5.00E+05
1.00E+06
1.50E+06
2.00E+06
2.50E+06
3.00E+06
3.50E+06
4.00E+06
4.50E+06
date of observation
rainfall[m
m/day]
Wadifl
ow[m
/da
y]
wadi flow
rainfall
0
10
20
30
40
50
60
70
80
31. Jan 93 28. Okt 95 24. Jul 98 19. Apr 01 14. Jan 04 10. Okt 06 06. Jul 09
0.00E+00
5.00E+05
1.00E+06
1.50E+06
2.00E+06
2.50E+06
3.00E+06
3.50E+06
4.00E+06
4.50E+06
date of observation
rainfall[m
m/day]
Wadifl
ow[m
/da
y]
wadi flow
rainfall
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Monitoring
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noble gases
Isotopes and hydrochemistry
stable isotopes
and radionuclides
Use of:
see presentations Mr. Khalid Al-Mashaikhi and Mr. Christian Herb
for origin and age dating of groundwater
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Water Demand
- first water boreholes drilled in the Najd in the beginning of the 1970,
- Agriculture major water consumer (~ 90%)
since then more then 1000 boreholes were drilled
- increasing population >> increasing domestic, industrial, commercialand municipal demand
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Impact on groundwater resources
275
285
295
305
315
325
335
1993 1994 1995 1997 1998 1999 2001 2002 2004 2005 2006
1988
Time
GroundwaterLev
el[m.a.s.l.]
25 kmAqu C
Aqu B
Aqu A265
Groundlevel329
O
2003
275
285
295
305
315
325
335
1993 1994 1995 1997 1998 1999 2001 2002 2004 2005 2006
1988
Time
GroundwaterLev
el[m.a.s.l.]
25 kmAqu C
Aqu B
Aqu A265
Groundlevel329
O
2003
> use of fossil water
> groundwater depletion
limit of artesian flow 1988 and 2003observation values Aqu A, B, C in central Dhofar
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Study goals
Goal I: Understanding the hydrogeological systemarid area and scarce data
Goal II: Quantification of the water budget componentsprecise determination of groundwater resources, recharge and safe yield
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innovative tool for Assessment, Prognoses, Planning and
Management of water resources
Approach > Groundwater modeling
local groundwater modelgroundwater levels maintained by present-day
recharge
fine model mesh
vertical discretisation
steady state calibrationpredevelopment state
transient calibrationmodeling period 1970 to 2010
short term simulation long term simulation
regional groundwater modelchanging gradients due to changing climate
conditions
rough model mesh
one model layer
Isotopes and Chemistry2H, 18O, C14, C13, noble gases
transient calibrationalong flow paths
calibrated and validated localgroundwater model
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Geology
0 100 km
Upper
Umm Er Radhuma
UUER
Lower
Umm Er Radhuma
LUER
Tertiary
Sediments
(Hadramout
Group)
cretaceous
sediments
Arabian
Sea
Tertiary
Sediments
(Fars
Group)
0
250
500
750
[masl]
0 8000 16000 24000 32000 40000 48000 56000 64000 [m]
DAM
RUS
S N
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HydrogeologyFormation Lithology mean aquifer
thickness
(m)
mean storage
coefficient
mean
Transmissivity
(m/day)
Dammam
(DAM)
RUS
Formation
Limestone,
with Marl
Breccia, Marl,
laminated
gypsum
21 3.2e-06 485
Upper UER
grey to brown
dolomitic
limestone
16 1.0e-06 680
upper part of
Lower UER
lower part of
Lower UER
olive, sparry
limestone with
shale
23
73
1.5e-04
1.4e-05
556
13
- Aqu A (Central Najd) and Aqu B (Eastern Najd) have more local significance
- Aqu C and Aqu D are the most important sources of Groundwater
for domestic and agricultural use in the Najd
(GRC 2008)
Upper
Umm Er Radhuma
UUER
Lower
Umm Er Radhuma
LUER
0
250
500
750
[masl]
16000 24000 32000 40000 48000 56000 64000 [m]
RUS
Aqu A
Aqu B
Aqu C
Aqu D
DAM
direction of
groundwater flow
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Conceptual model Najd Aquifer System
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Conceptual model Najd Aquifer System
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Conceptual model Najd Aquifer System
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Groundwater Model
boreholes
3-D body
initial values + boundary conditions
calibration
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Pre-development state
GW-level
Aquifer C and D in m amsl
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Present situation
GW-level
Aquifer C and D in m amsl
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Groundwater discharge
- no monitoring of groundwater abstraction
- use of satellite imagery for agricultural areas
- assumptions for municipal and industrial demand
Thumrait
Hanfeet
Heelat
As SafaFarm
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Outlook
- transient model for the period 1970 to 2010
- including water chemistry and Isotopes
- defining discharge areas and discharge amount
- calibration of the transient model for the period 1996 to 2008
- comparison of monitored and simulated values with increasing drawdown
short-term modeling
long-term modeling
- developing model
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Acknowledgments
Thanks
for support and cooperation to the Ministry of Regional
Municipality and Water Resources, Sultanate of Oman
to the BMBF for funding the IPSWaT Scholarship
and to my colleagues from the Department of
Hydrogeology and Environmental Informatics
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Using a large scale groundwater model to quantify
water resources availability in an arid area
Thomas Mller1, Gerhard Strauch1
1Helmholtz Centre for Environmental ResearchUFZ, Department of Hydrogeology, Leipzig
Thank you very much for your attention!
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