WATER HARVESTING WATER HARVESTING AND CC ADAPTATION AND CC ADAPTATION IN THE DRY AREAS OF IN THE DRY AREAS OF

TUNISIATUNISIA

WATER HARVESTING WATER HARVESTING AND CC ADAPTATION AND CC ADAPTATION IN THE DRY AREAS OF IN THE DRY AREAS OF

TUNISIATUNISIA

Regional Consultation Meeting Climate Change Impacts in the Arab Region: Water Scarcity, Drought,

and Population Mobilityاإلقليمي التشاوري االجتماع

: وتنقل" والجفاف، المياه، ندرة العربية المنطقة في المناخ تغير تأثيراتالسكان"

September 16-15 2010 ٢٠١٠أيلول/سبتمبر 16-15سوريا دمشق ، Damascus , Syria –

Dr. Mohamed OUESSARInstitut des Régions Arides (IRA)4119 – Médenine – TunisieTél: 216-75633005; Fax: +216-75633006Email: Med.Ouessar@ira.agrinet.tn

• IntroductionIntroduction

• Basic principlesBasic principles

• DevelopmentDevelopment

• Overview of WH in TunisiaOverview of WH in Tunisia

• CC in TunisiaCC in Tunisia

• WH & CC adaptationWH & CC adaptation

• Conclusions & prospectsConclusions & prospects

The dry areas are characterized by: The dry areas are characterized by: rainfall is rainfall is rare, variable and torrentialrare, variable and torrential

Insufficient to meet the basic needs for crop Insufficient to meet the basic needs for crop production,production, Poorly distributed over the growing season Poorly distributed over the growing season risky risky farmingfarming Runoff can cause erosion and be lost later by Runoff can cause erosion and be lost later by evaporation from swamps ‘salt sinks”,evaporation from swamps ‘salt sinks”,

High temperature High temperature evapotranspiration evapotranspiration Shallow and poor soils Shallow and poor soils degradation, degradation, moisture stress moisture stress desertification desertification Dominating rainfed agricultureDominating rainfed agriculture

Collection areaCollection area

ReservoirReservoir

Target areaTarget area

DeprivingDepriving part of the land of its share of rain, which is usually small part of the land of its share of rain, which is usually small and non productive, and and non productive, and addingadding it to the share of another part in order it to the share of another part in order to bring the available water amount closer to the to bring the available water amount closer to the water requirementswater requirements of of

crops (Oweis et al., 2001)crops (Oweis et al., 2001)

Runoff harvesting –additional 35%

of annual rainfall

150 mm

200

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

100

200

300

400

5007501000

1500

200

Sebkha

Wadi

LEGENDS Cereals

Forests

Irrigation Fruit trees Rangelands 690 Altitude

200 Isohyet

Agro-ecological zones

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300000 500000 700000

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0 60 12030Km

µ

MM EE DD

II TTEE

RRRR

AANN

EEAA

NN SS

EEAA

LL YY

BB II AA

A L

G E

R I

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Legend

Flood spreading

Jessour

Meskat

Wadi

!@ Gabion check dams

# Hill lake

º' Recharge wells

!. Large cistem

! Small to medium cistem

± Tabias

Sebkha

100

400

CatchmenCatchmenttCatchmenCatchmentt

CroppinCropping Areag AreaCroppinCropping Areag Area

Jessour

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

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70 80 90 100

rainfall in mm

harv

este

d ru

noff

in m

m

with all tabias

without tabias

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 yearETrel: relative ETa1: ETa with only rainfall on the terrace2: ETa with rainfall and runoff on the terrace3: ETa with rainfall, runoff and supplemental irrigation

Water balance in of jessour

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 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

0%

20%

40%

60%

80%

100%

VD VD D D D N N N N N W W W VW VW

Year

Recharge

Flowout

ET

0%

20%

40%

60%

80%

100%

VD VD D D D N N N N N W W W VW VW

Year

Recharge

Flowout

ET

SC0

SC2

VD ND W 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.

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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 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.