WATER HARVESTING AND CC ADAPTATION IN THE DRY AREAS OF TUNISIA

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WATER HARVESTING AND CC ADAPTATION IN THE DRY
AREAS OF TUNISIA
Regional Consultation Meeting Climate Change
Impacts in the Arab Region Water Scarcity,
Drought, and Population Mobility ????????
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??????" 16-15 ??????/????????? 2010 15-16
September ????? ?????Damascus , Syria
Dr. Mohamed OUESSAR Institut des Régions Arides
(IRA) 4119 Médenine Tunisie Tél
216-75633005 Fax [phone] Email
Med.Ouessar_at_ira.agrinet.tn
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OUTLINE
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• Introduction
• Basic principles
• Development
• Overview of WH in Tunisia
• CC in Tunisia
• WH CC adaptation
• Conclusions prospects

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INTRODUCTION
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• 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

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BASIC PRINCIPLE
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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
Runoff
Reservoir
Target area
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Runoff harvesting additional 35 of annual
rainfall
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DEVELOPMENT OF WH
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• 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, ).

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OVERVIEW OF WHT IN TUNISIA
Ben Mechlia Ouessar, 2004 Ouessar, 2007
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1500
1000
750
500
400
300
200
100
200
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Agro-ecological zones
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400
100
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CC IN TUNISIA
Minis. Agriculture, 2007
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Temperature increase (in C) for the 2020 (left)
and 2050 (right) horizons.
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Average annual rainfall decrease (in ) for the
2020 (left) and 2050 (right) horizons.
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WH CC ADAPTATION
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Case of Meskat
Snane et al., 1991
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ETa in a Meskat system for different CCR and
annual rainfall (green 413 mm Red 290 mm)
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Case of Tabias
Nasri et al., 2004
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Case of Jessour
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Water balance in of jessour
Hyd. Year ETrel (2/1) ETrel (3/1) ETrel (3/2)
Wet 1.1 - -
Dry 2.3 2.5 1.1
Very dry 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
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Watershed treatment
Schiettecatte et al., 2005 Ouessar, 2007
Ouessar et al. 2009
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SC0 SC0 SC1 SC1 SC2 SC2 SC3 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 0.1 c 0.0 0.1 c 0.0
Perco 14.5 a 7.9 24.3 b 13.2 28.2 b 15.4 28.3 b 15.4
TLOSS 28.0 a 15.2 8.2 b 4.4 3.1 c 1.7 3.2 c 1.7
Seepage 0 a 0.0 0 a 0.0 1.1 b 0.6 0.9 b 0.5
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SC0
SC2
VD
N
D
W
VW
VD
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Vulnerability of olive groves to CC
Sghaier et al., 2010
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CONCLUSIONS PROSPECTS
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• 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.

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• 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 létude de la
  destruction des jessour dans le sud tunisien.
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• De Graaff, J., Ouessar, M. 2002 (eds). Water
  harvesting in Mediterranean zones an impact
  assessment and economic evaluation. TRMP paper
  n40, 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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