Regional Consultation Meeting
Climate Change Impacts in the Arab Region: Water Scarcity, Drought,
and Population Mobility
‫االجتماع التشاوري اإلقليمي‬
"‫ وتنقل السكان‬،‫ والجفاف‬،‫ ندرة المياه‬:‫"تأثيرات تغير المناخ في المنطقة العربية‬
15-16 September 2010 ٢٠١٠‫أيلول‬/‫سبتمبر‬16-15
‫ سوريا‬،‫دمشق‬Damascus , Syria –
WATER HARVESTING
AND CC ADAPTATION
IN THE DRY AREAS OF
TUNISIA
Dr. Mohamed OUESSAR
Institut des Régions Arides (IRA)
4119 – Médenine – Tunisie
Tél: 216-75633005; Fax: +216-75633006
Email: Med.Ouessar@ira.agrinet.tn
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Introduction
Basic principles
Development
Overview of WH in Tunisia
CC in Tunisia
WH & CC adaptation
Conclusions & prospects
The dry areas are characterized by:
 rainfall is rare, variable and torrential
 Insufficient to meet the basic needs for crop
production,
 Poorly distributed over the growing season  risky
farming
 Runoff can cause erosion and be lost later by
evaporation from swamps ‘salt sinks”,
 High temperature  evapotranspiration
 Shallow and poor soils  degradation,
moisture stress  desertification
 Dominating rainfed agriculture
Depriving part of the land of its share of rain, which is usually small
and non productive, and adding it to the share of another part in order
to bring the available water amount closer to the water requirements of
crops (Oweis et al., 2001)
Collection area
Reservoir
Target area
200
150 mm
Runoff harvesting –
additional 35%
of annual rainfall
 As long as the people have inhabited the dry areas
and made cultivation, they have harvested water.
 In southern Jordan early WH structures are believed
to have been constructed around 5000 years ago,
 Southern Mesopotamia: 4500 BC,
 Negev desert: 1000 BC,
 Yemen (Tihama): spreading system dating 1000
years BC
 Pakistan (Balauchistan): Khuskaba and salaiba
systems
 Tunisia: Jessour, meskat and cisterns,
 Egypt (North west and Sina): wadi bed systems and
cisterns,
 Moroccco, Syria, Iran, Oman, : Groundwater
galleries (fouggara, falej, …).
Ben Mechlia & Ouessar, 2004; Ouessar, 2007
1500
1000
750
500
400
300
200
100
200
Agro-ecological zones










LEGENDS
 Cereals










 Forests
 Irrigation
Fruit trees
 Rangelands
Wadi
 690
Altitude
Sebkha
200
Isohyet



500000
700000
ME
#
#
R
E
ER
!@
#
!@
A L G E R I A
!@
#
!.
!@
Croppin
g Area
!.
!
#
!.
!@ !.
±
!@
!
±
±#
!.
±±
±
!@
±
!
3800000
!@
!
!
!.
#
!@
!@
!@ #
!
±
!
!@
º'
!
º'
400
100
!@
!@
#
!@
A
EA
SE
N S
AN
EA
NE
R
RA N
#
Catchmen
t
D
II TT
!@
4000000
300000
!@
!
!@
±
!@
!
±
3600000
!
!@
±
Legend
!
!
Flood spreading
!
±
Jessour
!
BB
!@ Gabion check dams
º'
#
µ
Hill lake
Recharge wells
!.
Large cistem
!
Small to medium cistem
±
A
II A
L Y
Wadi
Tabias
Sebkha
0
30
60
Jessour
3400000
Meskat
120
Km
Dike
Minis. Agriculture, 2007
Temperature increase (in °C) for the 2020 (left) and 2050
(right) horizons.
Average annual rainfall decrease (in %) for the 2020 (left) and
2050 (right) horizons.
Snane et al., 1991
ETa in a Meskat system for different CCR and annual
rainfall (green: 413 mm; Red: 290 mm)
Nasri et al., 2004
400
with all tabias
350
without tabias
harvested runoff in mm
300
250
200
150
100
50
0
0
10
20
30
40
50
rainfall in mm
60
70
80
90
100
Water balance in of jessour
Hyd. Year
Wet
Dry
Very dry
ETrel (2/1) ETrel (3/1) ETrel (3/2)
1.1
2.3
2.5
1.1
12.0
15.6
1.3
Hyd. Year: type of the hydrological year
ETrel: relative ETa
1: ETa with only rainfall on the terrace
2: ETa with rainfall and runoff on the terrace
3: ETa with rainfall, runoff and supplemental irrigation
Schiettecatte et al., 2005; Ouessar, 2007; Ouessar et al. 2009
SC0
SC1
SC2
SC3
mm
%
mm
%
mm
%
mm
%
Rainfall
183.9
-
183.9
-
183.9
-
183.9
-
ET
107.0a
58.2
147.2b
80.1
150.9 b 82.0 150.9 b
82.0
Outflow
34.3 a
18.7
4.0 b
2.2
Perco
14.5 a
7.9
24.3 b
13.2
TLOSS
28.0 a
15.2
8.2 b
4.4
3.1 c
Seepage
0a
0.0
0a
0.0
1.1 b
0.1 c
0.0
0.1 c
0.0
28.2 b 15.4
28.3 b
15.4
1.7
3.2 c
1.7
0.6
0.9 b
0.5
100%
80%
60%
Recharge
SC0
40%
Flowout
ET
20%
SC2
0%
100% VD
VD
D
D
D
N
N
N
N
N
W
W
W
VW
VW
Year
80%
SC2
60%
Recharge
Flowout
ET
40%
20%
0%
VD
VD
VD
D
D
D
D
N
N
NN
N
N
W
W
W
W
VWVW
VW
Sghaier et al., 2010
Water harvesting techniques have been
developed since antiquity to cope with
climate variability in the dry areas.
They played major role in the
development of rainfed agriculture in
addition of providing other ecosystem
services
 With the prospect of CC, those
systems/techniques would be more useful.
Therefore, they need to be well considered
in the national/regional strategies for
adaptation with CC.
• Alaya, K., Viertmann, W., Waibel, Th. 1993. Les tabias. Imprimerie Arabe de Tunisie, Tunis,
Tunisia. 192 pp.
• Carton, D. 1888. Essai sur les travaux hydrauliques des Romains dans le Sud de la Régence de
Tunis. Bulletin Archéologique du Comité des Travaux Historiques et Scientifiques, 438-465.
• Chahbani, B. 1990. Contribution à l’étude de la destruction des jessour dans le sud tunisien.
Revue des Régions Arides, 1: 137-172.
• De Graaff, J., Ouessar, M. 2002 (eds). Water harvesting in Mediterranean zones: an impact
assessment and economic evaluation. TRMP paper n°40, Wageningen University, The
Netherlands.
• Fleskens, L., Stroosnijder, L., Ouessar, M., De Graaff, J. 2005. Evaluation of the onsite impact
of water harvesting in Southern Tunisia. Journal of Arid Environments, 62: 613-630.
• Genin, D., Guillaume, H., Ouessar, M., Ouled Belgacem, A., Romagny, B., Sghaier, M.,
Taamallah, H. (eds) 2006. Entre la désertification et le développement : la Jeffara tunisienne.
CERES, Tunis, 351 pp.
• Nasri, S. 2002. Hydrological effects of water harvesting techniques. Ph.D. thesis, Lund
University, Sweden, 104 pp.
• Oweis, T., Hachum, A., Bruggeman, A. 2004. Indigenous water harvesting in West Asia and
North Africa. ICARDA, Aleppo, Syria.
• Ouessar M. 2007. Hydrological impacts of rainwater harvesting in wadi Oum Zessar watershed
(southern Tunisia). Ph.D. thesis, Faculty of Bio-Engineering Sciences, Ghent University,
Belgium, 154 pp.
• El Amami, S. 1984. Les aménagements hydrauliques traditionnels en Tunisie. Centre de
Recherche en Génie Rural (CRGR), Tunis, Tunisia. 69 pp.
• Ennabli, N. 1993. Les aménagements hydrauliques et hydro-agricoles en Tunisie. Imprimerie
Officielle de la République Tunisienne, Tunis, 255 pp.
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