4th World Water ForumMexico march 16-22, 2006

Special session on« WUE in Agriculture and Potential for Water Saving in the Middle East Region »

CIHEAM/IAM-B

Water Use Efficiency and

Agronomic Techniques for Water Saving

Netij Ben MechliaInstitut National Agronomique de Tunisie- Tunisia

Precipitation Renewable (m3/cap.) (m3/cap.)(Km3) (Km3) (2000) (2025)

Algeria 163 14 450 300

Morocco 150 30 1000 800

Tunisia 34 4 450 300

Water Resources in North Africa

Cultivated and irrigated areas in North Africa (million ha)

Algeria Morocco Tunisia

Cultivated 8.0 9.6 4.9

Irrigated .6 1.3 .4

Conceptual Frameworkfor Efficient Water Management

A fundamental relationship between production (W) and transpiration (T) is:

W = mT/ETo

ETo is a measure of evaporative demand andm is a crop constant, (100-200Kg/ha/day)

for Efficient Water Use in Crop Growth (W) :

• Maximize m- select species of large m

• Maximize T- store water on appropriate soils- deep roots to extract all water- weed control, mulching- rapid crop growth

• Minimize ETo- select locations with small ETo- grow at times of year when ETo is small

Further requirements for yield (Y):

- maintain T for duration of crop cycle.

- avoid stresses at vulnerable times for yield formation.

- seek optimum balance of water use during vegetative and reproductive phases.

4-Practices to improve water productivity, WP

0

10

20

30

40

50

60

70

80

50 150 250 350 450 550 650

ETa (mm)

Yiel

d (q

t/ha)

Rainfed

Irrigated

1. Supplemental Irrigation

yield of wheat under S. I. and Rainfed conditions

2. Water harvesting

WH has an advantage if :

• Soil has good water-holding capacity.• Crop relies on stored water.

When

Rainfall is infrequent.Lasting drought is probable

3. Deficit Irrigation

the rationale of DI is to reduce irrigation during periods of vegetative growth of plants, thus effects on yield are minimized.

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80

PrimeurSaisonArrière saison

Ren

dem

ent r

elat

if (Y

/Y10

0 )

Réduction de l'irrigation (%)

Deficit irrigation of Potatoes

Deficit Irrigation of Peach Trees

0.6

0.8

1

1.2

0 10 20 30 40

Y/Yo

Irr. Deficit (%)

DI-Spring

DI-Summer

DI-Continuous

Full Irrigation

4. Inter Cropping: adjusting cropping systems to unreliable water supply

R1

R2 R4

R3

Rainfall

ETR

Irrigation

Inter- cropping systems: association of cereals and olive trees

Future Challenges

• reduce the need for more water supply

• improve food security

Assessment of water harvesting and supplemental irrigation potential in arid and semi-arid areas of West Asia and

North Africa

Assessment of water harvesting and Assessment of water harvesting and supplemental irrigation potential in arid supplemental irrigation potential in arid and semiand semi--arid areas of West Asia and arid areas of West Asia and

North AfricaNorth Africa

< 200 mm200-400 mm400-600 mm600-800 mm800-1000 mm1000-1200 mm> 1200 mm

PrecipitationPrecipitation mapmap

ElevationElevation mapmap

0-100100-200200-400400-600600-800800-900900-12001200-1600

Hill reservoirsHill reservoirs

Capability of the methodology developed to identify hill reservoirs potential sites

Validation of the methodology using ASTER 2003Validation of the methodology using ASTER 2003

MeskatMeskat

MappingMapping oliveolive--MeskatMeskat usingusing LandsatLandsat ETM imageETM image

Re f

l ec t

anc e

Bands

Subset Unsupervisedclassification

Landsat ETM Image 06 March 2002

RGB 453

Olive Class

00.10.20.30.40.5

ETM1 ETM2 ETM3 ETM4 ETM5 ETM7

Thank you for your attention