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