What technology where?

Crop and Environmental Sciences DivisionCrop and Environmental Sciences DivisionInternational Rice Research InstituteInternational Rice Research Institute

Los BaLos Bañños, Philippinesos, Philippines

• Nature of water scarcity (“imposed”, natural, physical, economical)• Socio-economic setting (price of rice, price of water, water market, water rights, labor availability, gender issues)• Technical infrastructure (water control, irrigation system)• Organizational infrastructure (water user groups, irrigation association)• Policy (water pricing)

Boundary conditions and settings

Yield

Low High Water availability

Flooded lowland

Upland

Crack plowingCompactionGood puddling……..‘Safe’ AWD

Aerobicrice

Response options to level of water scarcityResponse options to level of water scarcity

Diversification(nonrice crops)

0

5

10

Furrow, Flush, Sprinkler Irrigation S

SC

Soil Management,Reduced water depth

Y = f (variety, management)

Technologies to reduce water input

AWD

Lowland rice system

Aerobic rice system

Traditional upland rice

system

Water availability High

Low

Soil Condition

FC S

Aerobicc

Flooded

Yield (t ha-1)

0

1

2

3

4

5

6

7

8

9

10

200 400 600 800 1000 1200 1400

Yield (t ha-1)

Water input (mm)

aerobic

flooded

Cross-over point flooded - aerobic

Scale level User Objective

Field Farmer Yield, income

Small landscape Competing farmers

Governor, mayor,..

Competing income

Votes, regional production

Irrigation system Competing farmers

Managers

Hydropower, industry, city

Recreation

Competing income

Equity, production, $$

$$

$$

Region, province, catchment

Competing farmers

Governor, mayors,..

Hydropower, industry, city

Recreation

Nature

Competing income

Votes, production, $$

$$, $$, $$

$$

Various services

Country All the above, competing

All the above, competing

Scale considerations

Scale considerations

Loss from field is not always loss from systemIncreasing options for water reuse with increasing scale

y = 0.0046x + 0.8885

R2 = 0.9049

y = 0.0013x + 1.1412

R2 = 0.9174

0

10

20

30

40

50

60

70

80

90

100

0 5000 10000 15000 20000

Water reuse (106 m3)

Area (ha)

Integrated approach

Zanghe Irrigation System. 160,000 ha mainly rice

0

100

200

300

400

500

600

700

800

1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998

IRRIGATION

OTHER USES

Water allocation (106 m3)

Year

Other users:Hydropower, city, industry

Responses

• Double rice => single rice (same total yield, less water• Active promotion AWD• Farmer organization in water user groups• Volumetric water pricing• System modernization (water control, canal lining, water measurement)• Thousands of ponds for water reuse

N

MAP OF WENJIAXIANG SITE IN CHINA

N

TanksGPS Measurements points

Boundary

Irrigation Canals

Drainage CanalsRoads

Ju zh an g R

i ver

Dangyang Ci ty

Zhi jiang Ci ty

Yangtze River

Zhanghe Reservoi r

Zhanghe Project Administration*

Th e

Fir s

t M

ain

Can

a l

Jiangl in Ci ty

Shashi Ci ty

Jinmen City

*Wenjiaxiang

Zhongxiang Ci ty

*Tuanlin

*Shayang Ci ty

Changhu Lake

The Fourth Main Canal

General Main Canal

Z H A N G H E I R R I G A T I O N D I S T R I C T

Designed Irrigated areaCatchment area reservoirArea with supplementary Irr igation, prone to flooding

RiversReservoirs

Main Irrigation canalsIrrigation canalsDrainage canalsNatiral streams

Railway trackRoads

Cities

IW MI - J ANU ARY 20 0 0

So ur ce : Zha ng he Pro ject Adm inis tra tio n De ce mb er 19 86

Water re-use through reservoirs and on-farm pondsWater re-use through reservoirs and on-farm ponds

0

200

400

600

800

1000

1200

1400

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001

0

100

200

300

400

500

600

700

800Water for irrigation (106 m3) Rice production (1000 t)

Rice

Water

Year

More rice using less water!

When water is scarcer than land, maybe maximize water productivity instead of land productivity (= yield)

Suppose:• Irrigation command area of 10,000 ha• Reservoir with 69 106 m3 capacity• Water shortage: only 56 106 m3 available

Rice Yield (t ha-1) Water (mm) WPIR

Flooded 7.4 0.69 1.06

AWD 6.7 0.37 1.81

Conventional

(less area)

Area

(ha)

Water used

(106 m3)

Production (103 t)

Flooded rice 8,000 56 59.2

Fallow 2,000 - -

AWD - - -

Total 10,000 56 59.2

Alternative Area

(ha)

Water used

(106 m3)

Production (103 t)

Flooded rice 5,680 40 42.0

Fallow - - -

AWD 4,326 16 29.0

Total 10,000 56 71.0

Two “response options”

Maximized water productivity

• Higher total production• Increased equity among farmers• No land abandonment