1

IMPROVING WATER AND LAND MANAGEMENT FOR EFFICIENT WATER USE IN IRRIGATED AGRICULTURE

Luis S. Pereira

Vice-president Hon., ICIDPresident, CIGR

Technical University of Lisbon

The 19th ICID Congress, Beijing, Sept. 2005

Q52.1: On-farm water and soil management;Q52.2: Performance evaluation and integrated

management of irrigation and drainage systems;

Q52.3: Conjunctive use of water to optimize food production;

Q52.4: Policy options for water saving in irrigation;Q52.5: Management transfer and participatory

irrigation and drainage management;

Q52.6: Application of information technology in irrigation and drainage management.

Q52. IMPROVING WATER AND LAND MANAGEMENTFOR INCREASING EFFICIENCY IN IRRIGATED AGRICULTURE

Tozeur

For millennia, civilisations developed in water scarce environments. The respective cultural skills are an essential heritage of those nations and peoples, and the humanity as well.

However, progress in XX century questioned the traditional know-how, which has been often replaced by modern technologies and management imported from different environments and cultures.

A water economic culture is now following a technical one, imposed when the large irrigation schemes were built. Both are generally imported from different cultural and instituttional environments.

Management faces therefore difficult challenges due to the fact that irrigators have a perception of problems, practices and objectives different from the non-farmer managers.

A turn in viewing traditional irrigation is starting in the non-technical media

But we need to help providing our know-how accepting farmers cultures and perception

Oasis of Turpan, Xinjiang

Pressures about water use in irrigation are coming from a ever growing urban society that understands less and less the rural world and, mainly, the peasants. Most common include:

“decrease water consumption” - when it should be said “control water demand”

Farmers may not have access to other and better technologies, and may do not know how to improve those they are using after centuries

2

Zairi et al., 2003

Reducing the demand for supplemental irrigation of cereals may be feasible if to decreasing Gross Margins per unit land (GM/ha)correspond increased GM per unit water. The farmer incomes then reduces but, when water is lacking, thatincome is higher than reducing the cropped area.

0

1000

2000

3000

4000

5000

240 320 400 480 560 640 720 800 880

Season irrigation (mm)

GM

(U

SD

/ ha)

(6) (8) (10) (12) (14) (16) (18) (20) (22)

Number of irrigations

r average ( ), high ( ) and very high ( ) demand conditions Zairi et al., 2003

However for crops having a high demand for water such as summer crops, including if they have a favourable ratio between yield price and water cost, e.g. tomato in Tunisia, when GM/ha decreases due to less water application

GM/ha

0.0

0.2

0.4

0.6

0.8

240 320 400 480 560 640 720 800 880

Season irrigation (mm)

GM

(U

SD

/ m3 )

(6) (8) (10) (12) (14) (16) (18) (20) (22)

Number of irriga tions

GM/m3

the GM/m3 do not increase. It is then questionable to adopt deficit irrigation

More knowledge about water-yield-revenues is required before adocating deficit irrigation for demand reduction

“pay the full costs of water”, but, …

what about yield prices and farmers revenues?

Paddies in the Po Valley, courtesy by M. Greppi

what about the externalities of irrigation such as aquifer recharge and flood control?

Impacts of water prices on water demand (and irrigated cropped area) at system level

Traditional irrigation, Duero Modern irrigation, Guadalquivir

Impacts of water prices on water demand, cropping pattern and income at farm level, Alentejo, Portugal

If water is to be paid in full as an economic good the demand will decrease together with the irrigated area and farm income Pinheiro and Saraiva, 2002

Japan. Inst. Irrig. Drain., 2003Mitsubishi Res. Inst., 2001

If multifunctions of irrigated agriculture are recognized, the water is “fully” valued and farmers will pay what is socially and economically acceptable

3

“improve irrigation efficiency”, but

New developed oasis near Tozeur, Tunisia

farmers generally know they need to apply water in excess to leach salts, to store water in the soil when deliveries are not reliable, or to overcome the distribution uniformity of the system

Mantovani, 1993

The depth of applied water D depends upon the technologies available. Improving them to achieve an high uniformity UC that provides for making D close to Dopt relates to the relationship between the price of the yield commodity (PY) and the cost of the water (PW)

“more crop per drop”, or “increase water productivity”. However, this may be achieved by improving agronomic practices not decreasing water use

Qingtongxia, Ningxia

Moreover, a peasant farmer, having 0.5 ha/family, do not understand the water productivity concept: he needs to increase land not water productivity, because it relates to the revenue he may get from his land

Maximing Yields or maximizing WP follow different objectives which relate to the socio economic farming conditions

Molden at al., 2003

There is a contradiction between water and land productivity that is solved differently by

a water manager Max(WP)a farmer Max(LP)

English et al., 2002

A key issue is to know the relationship between “applied water” and “costs” and “revenues”, maily these ones!

4

The farm’s socio economic conditions dictate options that may be different of those of water managers

Max net income for commercial farming Is below max Yield

(near max WP)

Max total income for small (family) farmers

Is near max Yield (far from max WP)

Where this water goes? To irrigation only?

Tank irrigation in Sigirya, Sri Lanka

May be it is worthwhile to adopt new water use concepts

WATER USE = Diverted for any purpose

CONSUMED FRACTION

NON-CONSUMED FRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

WATER USE

CONSUMED FRACTION

NON-CONSUMEDFRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

Beneficial

Non-beneficial

LOSSES

Non-beneficial (waste) Non-beneficial

Pathways to improve water use Pathways to improve water use

Maximize beneficial uses

Minimize non-beneficial uses

Control, avoid water losses

WATER USE

CONSUMED FRACTION

NON-CONSUMEDFRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

LOSSES

Beneficial

Non-beneficial

Waste

WATER USE

CONSUMED FRACTION

NON-CONSUMEDFRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

LOSSES

Beneficial

Non-beneficial

Waste

Identify the water pathways

A new approach looking the Basin and not the irrigated fields alone has been developed by IWMI along these lines

5

WATER DIVERSION

Agriculture Domestic Industry Environmentand other

Effective rain

Transpiration Soil evapor

Seepage +runoff

Conveyance + distribution

Application tocropped field

Percolation +runoff

Non-crop ET

YIELD

reuse

Classical transport & distribution efficiency

Classical application efficiency

WATER DIVERSION

Agricultureand landscape

Effective rain

Transpiration Soil evapor

Seepage +runoff

Conveyance + distribution

Application tocropped field

Percolation +runoff

Non-crop ET

YIELD

reuseTotal WP Irrig WP

WUE

Farm WP

WATER DIVERSIONAGRICULTURE

Reservoir

System

Field

YIELD

Crop ET

Leaching

BWU

Seepage + runoff

Non-crop ET

Evaporation

Percolation +runoff

N-BWU

WATER DIVERSIONAGRICULTURE

Reservoir

System

Field

YIELD

Crop ET

Leaching

BWU

Seepage + runoff

Non-crop ET

Evaporation

Percolation +runoff

N-BWU

WATER DIVERSIONAGRICULTURE

Reservoir

System

Field

YIELD

WATER DIVERSIONAGRICULTURE

Reservoir

System

Field

YIELD

Crop ET

Leaching

BWU

Crop ET

Leaching

BWU

Seepage + runoff

Non-crop ET

Evaporation

Percolation +runoff

N-BWU

Seepage + runoff

Non-crop ET

Evaporation

Percolation +runoff

N-BWU

NCF CF CF NCNRF NCRF

WATER DIVERSION

Agriculture(and landscape) Urban Industry Environment

and other

Reuse

Non-consumNon-reusable

Non-consumReusable

Consumpuse

treatment

Crop ET

Non-beneficial use

NetworkSeepage + runoff

Field Runoff + percol

Reusable

Wild ET Leaching

Non-reuse

Losses Wastes Beneficial use

LossesWastes

Beneficial + non-benef. use

Cons.use

Pathways to improve water use Pathways to improve water use

WATER USE

CONSUMED FRACTION

NON-CONSUMEDFRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

LOSSES

Beneficial

Non-beneficial

Waste

WATER USE

CONSUMED FRACTION

NON-CONSUMEDFRACTION

REUSABLENON-

REUSABLE

Degraded Quality

Preserved Quality

LOSSES

Beneficial

Non-beneficial

Waste

Identify the water pathways

Maximized beneficial uses

Minimized non-beneficial uses

Controlled, avoided water losses Efficient water use

High water productivity

6

On farm water management for efficient water use

Objective Technology Reduce demand Water saving

Water conservation Higher yields per unit of water Higher farmer income

• Select low demand crop varieties/crop patterns

• Adopt deficit irrigation • Improve irrigation systems uniformity and management

• Reuse water spills and runoff• Soil management/surface mulch

• Adopt best farming practices • Avoid crop stress at critical periods

• Select cash crops • Adopt appropriate irrigation technologies

Modern sprinklers may produce excellent performances in set systems, ...

if design is adequate and the selected system is appropriate for the local environmental constraints and farming conditions

The same applies to moving gun sprinklers under non-windy conditions ...

... and to the modern sprinklers in moving laterals. They produce excellent performances with low energy when design and management fit the environmental constraints

When micro-irrigation – drip, SDI, micro-sprinkling -are well designed and managed, performances can be excellent, but …

these are not achievable without appropriate support to farmers

Excellent performances may be achieved with surface irrigation when land levelling and irrigation technologies are appropriate

The challenge is to pay adequate attention and provide incentives to support farmers in improving their systems

Adopting zigzag furrowing, shortening the basin strips and using a PE pipe and valved tubing available in the market, this farmer reduced the demand from about 1500 to near 1000 mm. But DU still is very low because land is unlevelled!

7

With poor nozzling design, without assistance, what can this farmer do to get an uniform crop?

Near a tower, a well developed crop

In betwwen the towers, a less developed crop

The reality is far from ideal: without techical assistance, this farmer was unable to adequately use drip irrigation – he was using more water and expecting less yield than for his surface irrigated field, ...

...but Services in his region were just advising to move from surface to drip

1st case: basin irrigation in the Yellow River Basin

Huinong Irrigation System

This is an arid region, with very cold winter and rain generally < 200 mmMain crops are wheat and maize, often intercropped, and rice

Crop Irrigationsafterplanting

Seasonirrigation(mm)

Deeppercolation(mm)

GWc(mm)

ETcadj(mm)

ETc(mm)

Intercrop 6 630 386 471 810 816

Wheat 4 422 213 297 546 554

Maize 5 521 266 383 747 780

Present: excess water diversion causes high watertable and salinity, making inadequate the typical irrigation schedules

Pre-conditions for farm water savings and increased productivity:

1st: cut to about half the diversions from the river

2nd: rehabilitate the drainage system (without great investments)

3rd: reduce percolation (to the level required for leaching, upland crops)

Irrigation number

q (l s-1 m-1)

D (mm)

Zreq (mm)

Ea (%)

DUlq (%)

Percolation(mm)

1st 1.0 - 1.4 107 - 109 92 77.8 - 85.9 61.4 - 90.9 15 - 24 2nd 0.7 - 1.3 90 - 136 30 22.0 - 33.5 56.8 - 95.6 64 - 106 3rd 0.4 - 0.9 94 - 114 51 44.8 - 54.4 82.9 – 87.3 43 - 63 4th and 5th 1.2 105 - 157 50 25.6 - 35.2 84.4 - 92.7 12 - 77 6th 0.7 - 0.9 97 - 141 14 9.9 - 14.4 99.3 - 94.3 83 - 127

Present Irrigation Performances

Uniformity DU is acceptable to very good Efficiencies Ea are very low because

•Irrigations after the first are applied when there is too much water in the soil (lack of watertable control)•Applied depths are much above required•Percolation very high

8

Irrigation depths may be optimized according to pre-defined objectives. If yields are to be improved the total water application may have to increase but percolation is controlled.

Season irrigation volumes

0100200300400500600700

Intercrop wheat maize

Vol

umes

(mm

)

Deep percolation

0100200300400500600700

Intercrop wheat maize

Vol

umes

(mm

)

Present Improved Salt control Salt control with water savings

Zero level basins are required if such results are intended

1 2 3 4 5 6 78

9

ET+PercolationActual

0

50

100

150

200

250

Depth (mm)

GIRFARM(mm)GIDSUPPLY(mm)

Foreseen

Actual

0

500

1000

1500

2000

2500

3000

3500

Irrigation (mm)

Adopting low paddy water depths, improved delivery and irrigation scheduling, demand reduces by 50% and yields increase by 10%

Improved Irrigation Performancesimproved schedulecontrolled water tablezero levellinghigher inflow rates

field length of 48m

Irrigationnumber

q(l s-1 m-1)

D(mm)

Zlq(mm)

Ea(%)

DUlq(%)

Percolation(mm)

1st 1 130 112.0 84.3 75 20.43 113 106.9 97.0 93 3.2

2nd 1 123 110.3 89.5 85 12.93 113 108.3 97.4 95 2.9

3rd 1 119 108.2 92.1 88 9.33 111 106.7 98.5 95 1.5

4th 1 119 109.7 92.3 93 9.03 113 109.0 97.5 97 2.7

5th 1 120 110.5 91.4 92 10.23 112 108.5 97.4 96 2.8

Present

Drain+sched

40% Imp farm

50% Imp syst

Imp deliv+farm

no rice

High improv

V. High imp.

Max imp.

GM/Vol_DelivGM/Vol_Farm

0

0.5

1

1.5

2

2.5

Yuan/m3

Gross margin per unit water use, Huinong

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

0 1 2 3 4 5 6 7 8 9 10 Time implementation

Util

ity

farm gross margin delivery cost water use delivery

and to utilities show that more stringent improvements (after level 4) have relatively reduced impacts

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10

Time implementation (years)

Wat

er v

olum

es (1

0

3 m 3 /h

a/ye

ar) Total water use, TWU

Non-beneficial WU, farm Non-beneficial WU, delivery

Using a DSS mulyicriteria model applied to the system to analyse the foreseen improvements. results relative to water use

Improved 4

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

decade

wat

er v

olum

e (1

000

m3/

year

)

farm demandfarm consumptive usesimulated demand

Present

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

decade

wat

er v

olum

e (1

000

m3/

year

)

farm demandfarm consumptive usesimulated demand

Combined Improvements in delivery conditions, drainage, farm irrigation scheduling and basin irrigation systems lead to reduce the demand

at system and farm levels, and to increase the consumptive use

system demand

system demand

Present conditions

Improved to level 4

9

Improvements at farm – land levelling, inflow rates, irrigation scheduling – reduce the non-consumed and non-reusable fraction (percolation),

and the non-consumable but reusable fraction (runoff), mainly relative to paddies

Improved 4

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

decade

wat

er v

olum

e (1

000

m3/

year

)

farm demandfarm consumptive usefarm percolationfarm runoff

Present

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

decade

wat

er v

olum

e (1

000

m3/

year

)farm demandfarm consumptive usefarm percolation farm runoff

Present conditions

Improved to level 4

Fergana Valley2nd case: 2nd case: furrow furrow irrigation in irrigation in the Aral Sea the Aral Sea BasinBasin

Arid climate where excessive water use produced enormous changes in Aral Sea and river ecosystems

Main crops are wheat and cotton, furrow irrigation

2.39 2.36 1.79 1.78 1.791.78 1.21

Ea

Ea (adj tco)DU

DU (adj tco)0

10

20

30

40

50

60

70

80

90

100

Inflow rate (l/s)

Best performances are for alternate furrow irrigation

Efficiencies (Ea) are low except for alternate furrow irrigation due to excessive time of application. Uniformities (DU) are good/very good

Furrow irrigation with continuous flow to alternate or every furrow

Reducing cutoff times the irrigation depth D reduces, Ea improve, and DU decreases

0

10

20

30

40

50

60

70

80

90

100

%

2.4/1.2 2.4/1.2 2.4 2.4 3.0/1.5 3.0/1.5 2.4/1.2 2.4/1.2 2.4 2.4 3.0/1.5 3.0/1.5Inflow rate (l/s)

EaDU

Comparing continuous and surge flow, the later tends to provide for better performances

0

1

2

3

4

5

6

7

8

9

treatmentsEC ES AC AS Average

103 m3/ha or kg/ha D Yield

Water use is less for alternate furrows (A) than for every furrow irrigation (E) and also decrease from continuous to surge flow

However, the highest land/farm productivity is for continuous flow in every furrow

EC ES AC AS Average

ECES

ACAS

WP (irrig) kg/m3

WCF(field)

BWUF(field)

Ya/Ymax

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Every furrow continuous flow provides for maximizing yields (Ya/Ymax) but to minimal water use ratios. Opposite, alternate surge irrigation do not achieve maximal yields but highest WP(irrig) and highest beneficial water use fraction

However, if prices of production factors are high and those of commodities are low the farmer option is to maximise Ya/Ymax

10

Using a DSS in a GIS environment to evaluate alternative improvements operating

Satellite image

Fields layer

Irrigation network layer

Application to Fergana, Uzbekistan

Present

Cutoff-Ev

Sched-Ev

Sched-Alt

Def-Ev

Def-Alt

Surge-Ev

Surge-Alt

Sur-Def-Ev

Sur-Def-Alt

EconomicsUniformWater saving0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Glo

bal U

tility

Comparing alternative improvements through multi-criteria analysis, for the actual farming conditions in Fergana, the bestaletrnatives are the present one – no changes - or Sched + AC: The price of products do not compensate for improving farm irrigation. Surge flow has not enough economic return

Concluding: Knowledge and technologies exist that allow to make a more efficient the use of water in irrigation

These should mean capability to transfer into practice and to improve the existing irrigation, both at farm and system levels.However, knowledge and technologies progress much faster than technology transfer in case of small family and peasants farms

Technologies are easily available when manufacturers have an easy market, as it is for a variety of irrigation scheduling equipment adopted by commercial farms and for sprinkler and micro-irrigation equipment, the so-called “modern irrigation”. But when the markets have no quality exigences and control, the farmers may be purchasing less good equipment, poorly designed and demanding too much energy. In case of surface irrigation such market is generally not existing and surface irrigation becomes synonimous of “old fashion”

Knowledge and technologies that exist to provide for a more efficient use of water in irrigation need that appropriate quality control of equipments and management tools be enforced to support farmers in modernizing the systems

The constraints imposed to farmers, which they know well, need to be recognized, such as

inappropriate delivery conditions high costs of production factors, of irrigation equipments, low prices of commodities, low incomeslack of technical assistance and poor systems design

Using indicators need to be carefully done and taking into consideration the irrigator constraints, not to be used to describe environmental and managerial objectives

Incentives that compensate for the upgrading costs, society responsibilities, recognition of cultural skills, farmers decision making and not only PIM, need innovative approaches.