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Application of Isotope Hydrology in Groundwater Resources Management in Tunisia
DR. MOHAMED FETHI BEN HAMOUDA
Fulbright Visiting Scholar Division of Earth and Ocean Sciences
Duke University
CNSTN, Isotope Hydrology and Geochemistry Unit, Tunisia
1
University of Hawaii, Manoa Honolulu, April 1, 2015
2
Situation
Most experts consider a 1000 3m per capita per year is water shortage warning line. Tunisia is 393 cubic meters in 2011 !!!
Tunisia is considered as a freshwater scarcity country
3
Tunisia is a country of physical water scarcity, which means water resources development is approaching sustainable limits
4
Global Water Stress Indicator (WSI) for major water basins
The water basins in Tunisia are considered Over Exploited
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393*
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1850 mm Humid 1000 mm 750 mm Sub humid 500 mm Semi arid 300 mm Upper Arid 200 mm Under Arid 100 mm Desertic
Pluvial water resources 36 Billions 3m 225 mm/y
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8
Topography
Water resources 4850 Mm3
Surface water : 2700 Mm3
which 2 170 Mm3 can be mobilized
Groundwater resources 2125 Mm3
745 Mm3 shallow aquifers 1380 Mm3 confined aquifers 650 Mm3 are non renewable
9
10
11
Water resources mobilization and transfer
12
Na/Cl Br/Cl
Ratios
Piezometric
Salinity Nitrates
maps
Time series
PL +TDS
Isotopes
18O,2H
radioactive
Isotopes 3H, 14C
18O/Cl
Ratio
Localisation of
vulnerable zones
to the
overexploitation,
to salinisation
and pollution
Localisation
vulnerable
zones
to SW intrusion
Seawater fresh
water mixing
Origin and
mechanism of
salinisation
Preferential
zones
of recharge
and SW intrusion
Groundwater recharge
and origin
Interconnexion
between
Aquifers
Estimation
of renewal
and recharge
rate
Estimation of
seawater
fraction
Groundwater
Age dating,
Infiltation
velocity
COMBINED USE OF ISOTOPES AND CHEMISTRY GW.R.M
13
take advantage of
natural variations of isotopes
in water to study
hydrological systems
Stable Isotopes In Hydrology •Isotope fractionation
IAEA-WMO Global Network for Isotopes in Precipitation (GNIP)
15
-40
-30
-20
-10
0
-7 -6 -5 -4 -3 -2 -1 0
d2H
(‰
) V
s S
MO
W
d18O (‰ ) Vs SMOW
Plio quaternaire 2001"
Droite météorique mondiale DMM
Droite météorique locale Tunis Carthage
Miocène 2001"
Oligocène 2001
Evaporation line
Mixing line with sea water
Plot of 18O-2H in the Eastern Coast aquifer
1st group: Contribution of rain recent recharge
2nd group: influence of SW intrusion and evaporation
P.Q Shallow aquifer:
M & O deep aquifers:
Isotopic fingerprint Caracteristic of old water
Stables isotopes (18O, 2H)
Old water
Recent water
1
10
100
1,000
10,000
1955 1960 1965 1970 1975 1980 1985 1990
YEAR
TR
ITIU
M
[TU
]
KAITOKE,
NEW ZEALAND
VIENNA, AUSTRIA
Tritium in Precipitation
1 TU = 0.118 Bq/l
Undergo a Radioactive
decay
Tritium 3H indicator of recent rechage
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Tritium distribution map
Low content in 3H Deep aquifer
Fingerprint of Old water Low content :
Up flow
PQ (CO) , Q (H) : High 3H content recent water + Post nuclear water
High content 3H near the rivers
Recharge from rain water
0 2 4
Km
Sidi
Daoud
Azmour
El
Haouaria
Mer
Méditerranée
Dar
Allouch
Mer Méditerranée
Kelibia
Nabeul
Korba
0 5 10
Km
14C Groundwater Dating
0
10
20
30
0 20 40 60 80 100
Distance (km)
14C
go
run
dw
ate
r ag
e (
ka)
confined (artesian) conditions unconfined (phreatic) conditions
Flow velocity = 2.2 m/a
After Vogel et al. (1982)
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Distribution map of 14C in the Eastern cost aquifer
High activities in 14C PQ aquifer
Near the rivers
confirmation stable isotopes results
High recent recharge
Flow velocity: 0.3 to 2 m/year
Low activities Miocene et Oligocene:
Old water fingertprint
14C dating ages confirm hydrogeologic information
Mer
Méditerranée
Kelibia
Nabeul
Korba
0 5 10
Km
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Pliocene confined aquifer: Corrected Ages from 100 to 16000 years according to the depth and undergroud route
Shallow aquifer: recent water (High 14C activities)
Low water velocity 0.2 to 2.5 m/year
Sidi Daoud
Azmour
El Haouaria
Mer Méditerranée
Dar Allouch
Distribution map of 14C in El Haouaria aquifer
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Korba
Kelibia
Mer Méditerranée
Nabeul
0 5 10
Km
Map of localisation de recharge and overexploitation zones
Pizometric data with (18O +2H), 3H, 14C
E : Exploitation CO: The inertia zone is located in the south of O. Boulidine (interconnexion between aquifers).
R : Recharge
R : Recharge
E : Overexploitation : PL < 0 ; Continious decrease (time series)
PL > 0 ; rise in PL (time series)
(18O +2H) close to WA isotope composition TC
3H:
14C:
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Sidi Daoud
El Haouaria
Mer Méditerranée
Dar Allouch
H: the inertia zone is very limited due to the small surface and the thikness of the aquifer
E : Exploitation
R : Recharge
Map of localisation de recharge and overexploitation zones
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Conclusion for these 2 aquifers in term of Groundwater recharge Management
stable Isotopes
18O , 2H
Tritium 3H
PQ, Q Aquifers recharged
Rain water
14C GW Dating
PQ, Q: High Act. O,M,P: Low Act
•Ages 0 to 16000 years •Tr= 0.3 % •Recharge 12 mm/an
• in the preferential zones of recharge authorize
exploitation • Zones of overexploitation
Establish a save and forbidden areas
Fast Infiltration Seawater Intrusion
•Post Nuclear •Last decades •Up flow
Monitoring Pizometry
Hydrogeologic informations
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In Tunisia we have Forbidden & Save areas: 32 Save : 23 (green) Forbidden: 9 (red)
Upstream watershed: 418 km2
Capacity: 130.106 m3
Leak: 500 l/s to 120 l/s
Use of geochemical and isotope tracers for the characterization of water leakage at the Joumine dam, Tunisia
reduction of 75% of leakage
2000 tons of mining residues in the sinkhole
observed: D1 and D2
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After its construction Leakage of 500 l/s
Evolution of salinity and water level in reservoir from 1985 to 2011
40
50
60
70
80
90
100
0
1000
2000
3000
4000
5000
6000
5/6
/84
5/6
/86
5/6
/88
5/6
/90
5/6
/92
5/6
/94
5/6
/96
5/6
/98
5/6
/00
5/6
/02
5/6
/04
5/6
/06
5/6
/08
5/6
/10
Wate
r re
serv
oir
lev
el
in (
m)
Salin
ity i
n (
mg
/l)
Date
Average Reseroir D 1 D 2 P 26 P 57 Water Level
Construction of the
dam Injection of
material
Decrease of the flow rate was accompained by an increase of the Salinity in D2
27
Which was interpreted as a risk of stability of the dam
Geologic map of the Joumine dam (2013)
The two pillars integrated Cretaceous limestone, based on Triassic formations
28
Determination of origin and paths of leaks
Quantify leakage
Reduce the risk of security and stability of dam
Corrective action to minimize losses
Water level, Temperature and EC at boreholes
29
Water samples geochemical and isotopes
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Upstream downstream
Piezometric map at Joumine dam (2013)
Valuable information on the local groundwater flow and hydraulic connections in the dam and in the surrounding areas
The leakage emerging in D1 and D2 is related to infiltaration occuring near the uptake tower were the sinkhole was found
The arrows show the preferential pathway of water escarping from Reservoir
31
Similar EC in R & D1
D2: EC 2.34 mS/cm
The 2nd hypothesis was the valid one
It was not clear high salinity Dissolution of material used for the dam construction
Distribution of EC values at the Joumine dam expressed in mS/cm at 25 °C
Consequence of GW discharging from the underling Triassic formations
32
The samples which are located on the paths of leaks have a Temperature close to the R
Temp °C best
traceur for leaks
Temp R= 14.5 °C
Distribution of temperature in °C values at the Joumine dam
33
34
0.00
5.00
10.00
15.00
20.00
25.00
0.00 20.00 40.00 60.00 80.00 100.00 120.00C
on
cen
trati
on
(p
pb
)
Time since injection
Drain I
Rhodamine
Uranine
0
100
200
300
400
500
600
700
0.0 20.0 40.0 60.0 80.0
Co
ncen
tra
tio
n (
pp
b)
Time in hour after injection
Drain II
Uranine
Rhodamine
Breakthrough curves obtained in drain D1 and D2
dttC
AQ
dttC
VQ
)( were
)(
Where A indicate the surface of the curve, Q represent the flow rate C: concentration T: time
slQslQ DD / 28.44et / 88.57 21
dttCA )(
C
t A
Injection
Piper Diagramm
Various chemical water types
The reservoir & D1 same facies
The SI gypsum / SO4 relationship
Water is unsaturated Vs. gypsum and anydrite
Progressive Saturation Vs increase in SO4
35
-40
-30
-20
-10
-6 -5 -4 -3 -2
Global meteoric water line
Tunis Carthage meteoric local line
Joumine
Old water
recent water
EvaporationLine
P55
P24
P57P22
P49
P12P41
P2
P42
P57-2
D2
P57-14
P21 P57-1
D1R
d18O (‰)
d2H
(‰
)
Correlation (2H, 18O) in Joumine dam
1st group: -4,4< 18O<-3,7 Proximity to the reservoir: same origin :water leakage
2nd group: -5,6<18O<-4,9 Water depleeted: Local groundwater
confirming the above fact that the reservoir water is the main source of water leakage
36
Map of distribution of Tritium in Joumine dam (2013)
1st group 1,2 UT <Tritium<5UT Recent water coming from reservoir.
2nd group: 1,2 UT < Tritium Old water mixing with water coming deep aquifer.
Determine the pathways of water leaks and estimate any recent recharge to the aquifer from the reservoir
37
Watershed of Medjerda river, NW Tunisia
Determination of suspended elements in Medjerda river by using nuclear probe
20 to 25 Mm3
sediments / year
Loss of 0,5 % of storage capacity
Clogging of hydraulic infrastructure
Sedimentation of wadi’s beds
38
Emplacement
du détecteur NaI
Connexion
électrique du
détecteur NaI
Tige de manipulation de la protection de la source
Source radioactive
Joint
Bouchon métallique
Conteneur métallique
Support en plastique
de la source
Cale en plastique
Détecteur NaI
Armoire de
commande
Socle en béton
Porte
source et
détecteur
Translation
verticale de
la colonne
Rotation vers deux
directions
Manivelle de
manutention
Panneau solaire
Pluviomètre
SCHEMA GENERAL DE LA STATION AVEC LES STRUCTURES METALLIQUES
Armoire de
commande
Socle en béton
Porte
source et
détecteur
Translation
verticale de
la colonne
Rotation vers deux
directions
Manivelle de
manutention
Panneau solaire
Pluviomètre
SCHEMA GENERAL DE LA STATION AVEC LES STRUCTURES METALLIQUES
General outline of measuring station with the metallic structures
CCI
Iwsm 1exp
0
wss
wsm
C
µs: sediment mass attenuation coefficient
µw: :Water mass attenuation coefficient
ρm: density of the water-sediment mixture
ρs: density of sediments
ρw: density of water
I: intensity of radiation through a thickness of water with a concentration C. I0 : intensity of the emitted radiation.
Implementation of the radioactive source and the NaI detector in the probe 39
40
41
y = 0,1517x 1,8499
R 2 = 0,99
0
200
400
600
800
1000
1200
0,5 1,5 2,9 4,3 5,3 6,4 7,4 8,4 9,4 10,4 11,4
H(m)
Q(m3 s
-1)
Level of water in river depending on the pressure
Gauging Curve at Slouguia station
1.49
4mAH(m)
Determination of level of water in river
Determination of flow rate in river
43
y = -3919x + 24383R2 = 0.99
0
5000
10000
15000
20000
25000
0 1 2 3 4 5
Co
mp
tage (C
PM
)
C(g/l)
Counting & concentration of SE Relationship
3919
24383)/(
CPMlgC
Determination of the concentration of suspended elements
NaI detector converts into electrical impulses recorded radioactivity in CPM
44
Determination of solid flow Gs of suspended elements Crossing the section of the river
CQsKgGs )/( with Q : flow rate (m3 s-1) C : concentration of suspended elements (kg m-3)
m3/s D
ébit
(Q)
Volume total d’eau m3
mm
Plu
vio
métr
ie
Kg/m3
Cence
ntr
ation d
es
sed.s
usp
C
Gs Kg/m3
Tra
nsp
ort
des
Sed.
Temp (s
Poids total (Kg
45
Example of hydrological parameters over 2005 at Slouguia Station
Big fluctuation of the sediment concentration
concentrations varies from 0.1 to 6 g/l
The amount of sediment during this period was estimated at 780 000 T.
46
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60 70 80 90 100
Pro
fon
deur
(cm
)
Distance (m)
profil 2003 profil 2001 profil 1996 profil 1993
R.GR.D
Profile across the wadi Medjerda at Slouguia station
Continuous sedimentation of Medjerda since entry into service of the Sidi Salem dam
47
• Activities with IAEA: • RAF/0/038: Promoting Technical Cooperation Among Developing Countries (TCDC) in
Africa through Triangular Partnerships: Use of geochemical and isotope techniques to improve water resources management of coastal aquifers in Senegal and Tunisia. (2014-2015)
• Participation in the TC project TUN/7/001: Assessing the Impact of Uses and Management Practices on Water Resources Using Isotopic Techniques to Improve Water Resource Management (2012-2013).
• IAEA Project Counterpart TUN/8/017
• IAEA Project Counterpart TUN/8/014: Evaluation of erosiont and sedimentation in the Medjerda River, (2001-2002).
• IAEA Project Counterpart TUN/8/015: Assessment of marine intrusion in coastal aquifer systems of Cap bon, (2001-2002)
• *Course Director of IAEA training in Isotope Hydrology with particular emphasis on Dam Safety, 22-26 April 2002, Tunisia
• * IAEA Project Counterpart: INT/5/144: Sustainable Utilization of Saline Groundwater and Waste Lands, (1997-2001).
• *Project Counterpart RAF/8/028 “Investigating Dam and Reservoir Leakage and Safety in Africa”, (1998- 2002)
• *Participation in the TC project TUN/5/017: Nuclear Techniques to improve Water and Soil Management of Kairouan plain.
48
Visit of IAEA Director General Yukiya Amano to the Isotope Hydrology Laboratory
CNSTN, Tunisia, 25 June 2012.
49
Isotope Ratio Mass spectrometry Lab
50
Carbon 14 for Groundwater Dating Lab
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GEOCHEMISTRY LABORATORY
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ATLAS - Presents summary information of about 10,500
water samples - 26 countries and 79 IAEA projects
Thank you!
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