water harvesting and cc adaptation in the dry areas of tunisia regional consultation meeting climate...
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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: [email protected]
• 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
AA
L G
E R
I A
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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• 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.
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• 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.
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