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

5

393*

6

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

7

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

17

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)

20

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

21

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

22

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:

23

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

24

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

25

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

26

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

30

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

51

GEOCHEMISTRY LABORATORY

52

ATLAS - Presents summary information of about 10,500

water samples - 26 countries and 79 IAEA projects

Thank you!

54