RiceWaterv2 - IRRI Rice Knowledge Bank

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RiceWaterv2 - IRRI Rice Knowledge Bank
Rice and water
Crop and Environmental Sciences Division
International Rice Research Institute
Los Baños, Philippines
Irrigated rice and water
• 95% of the world’s rice is produced in Asia
• 75% of rice produced is irrigated (75 m ha)
• Irrigation in developing countries:
uses 80-90% of fresh water developed
In Asia: > 50% of this is for rice
• Rice requires much water: 3000-5000 l kg-1 rice
• Rice receives 34-43% of world’s irrigation water
• Rice receives 24-30% of world’s developed fresh water
• Rice is biggest single ‘user’ of developed fresh water
106 ha
300
250
200
150
100
50
0
World irrigated area
World irrigated rice area
Asia irrigated area
km3
4000
3000
2000
1000
0
World water withdrawal
Rice water use in irrigation
World water use in irrigation
Why does rice require so much water?
Field water balance lowland rice
Computing water balance
Input – outputs = storage change
Neglect storage change: Inputs = outputs
Measure (weir, flume, flow meter)
“Rest term”
Irrigation + rainfall = seepage & percolation +
evapotranspiration
Measure (rain gauge)
Calculate (Penman, pan evaporation)
Water requirements in lowland rice
Daily (mm d-1) Season (100 d)
Land preparation
175-750
Evapotranspiration
Wet season
Dry season
Seepage & percolation
Heavy clay
Loamy sand
(30-40% evaporation)
Total season
Typical value
4-5
6-7
400-500
600-700
1-5
25-30
100-500
2500-3000
: 675-4450 mm
: 1300-1500 mm
Examples water use; China 1999-2000
ZIS (Wuhan)
• Experiment
• Farmers
• Mezo site
Shimen (HZ)
• Early
• Late
Water (mm)
SP (mm d-1)
750-1150
650- 940
750-1525
4.0-6.0
1.6-2.8
4.0-8.0
850-950
575-700
1.0-6.0 (3.8)
1.0-6.0 (3.8)
Examples water use; Philippines 1988-2001
Guimba 88
89
90
91
Muñoz 91
Talavera 93
San Jose 97
San Jose 96
97
PhilRice 01
Water (mm)
2197
1679
2028
3504
SP (mm d-1)
18.3
12.5
16.4
32.8
1019-1238
577- 728
2874
1417 (DS)
1920 (DS)
600
5.2-7.6
0.3-2.0
25.8
9.6
15.2
1.1 (-> 4.4)
Groundwater: a “hidden” source of water
Groundwater depth (cm)
(cm)
20
20
0
Groundwater depth (cm)
Day number
0
168
-20
193
218
243
268
293
-20
-40
-40
-60
Flow ering
-60
-80
-100
Harvest
Panicle
initiation
-80
18
38
58
78
98
118
Day number
Tuanlin, China, 2002
-100
Changle, China, 2002
Groundwater depth (cm)
20
-20
-60
Direct uptake of water by
plant roots
-100
-140
-180
-220
-260
Dolores, Philipines, 2002
37375
37368
37361
37354
37347
37340
37333
37326
37319
37312
37305
37298
37291
37284
37277
37270
-300
Where do the outflows go?
Evaporation and transpiration: unrecoverable
Overbund flow, seepage, percolation: reusable
Pokhara, Nepal, 2006
Surface and subsurface water flows across a
toposequence of rice fields. D = drainage (over-bund
flow); I = irrigation, P = percolation; S = seepage.
Water re-use through reservoirs and on-farm ponds
ZH AN G HE IR RI GA TI ON D IST RI CT
MAP OF WEN JIAXIANG SITE IN CH INA
N
g
an
Zh
R
r
iv e
Ju
R iv
er
Zhon gx iang
Ci ty
The F ourth
M ai n C anal
We njia xi ang
*
Zhan ghe
Reservoi r
Ji nm en Cit y
jin g
T he
W es
M ain
t
C an
al
H an
R iv
er
*
Gene ral Ma
in Canal
Th e
M ai Se c on
nC
d
an al
Tuan lin
*
ird l
Th n a
e Ca
T h in
Ma
T he Firs t
M ain Canal
Zhan ghe P roject
A dm inis trat ion
Dangyang
Ci ty
*
J uz han
Sh ayang
Ci ty
r
g Ri ve
Zhi jian g
Ci ty
R oa d s
Changh u Lak e
D ra in ag e C a na ls
Ji angl in
Ci ty
Ir ri ga t io n C a n al s
Bo u nd ar y
Sh as hi
Ci ty
G P S M e as ur em en ts p oi nts
T an k s
er
Y angt z e Riv
Ra i lw a y tr ac k
Ro a d s
Ma i n Ir rig a tio n c an a ls
Ir ri ga ti o n c a na l s
Dr a in a g e c a na l s
Na ti ra l s tre a ms
Ci ti es
Ri v er s
Re s e rvo i rs
IW MI - J ANU ARY 20 0 0
So ur ce : Z ha ng he Pro ject Adm inis tra tio n De ce mb er 19 86
N
De s ig n e d Ir ri ga te d ar e a
Ca tc hm e n t a re a r e se rv oi r
Are a w ith s up p l em e n tar y Irr ig a tio n , p ro ne to flo o d in g
UPRIIS irrigation scheme,
Philippines
District I: 18,000 ha
Increased production with
increase in scale, using
same amount of irrigation
Water re-use by pumps:
• 18% farmers
• 23% area
• 10% water reused
Reuse surface water by
small dams
• 45% water reused
Water reuse (106 m 3)
100
90
y = 0.0046x + 0.8885
80
R = 0.9049
2
70
60
50
40
y = 0.0013x + 1.1412
30
2
R = 0.9174
20
10
0
0
5000
10000
15000
20000
Area (ha)
Water reuse by check dams in creeks/drains (♦) and
by pumping from shallow groundwater (◊)
District I, UPRIIS, Philippines, 2002
Water productivity (WP)
Amount of grain produced per unit of water used
kg grain m-3 water
What water used?
WPT
WPET
WPI
WPIR
: water transpired
: water lost by evapotranspiration
: water put in by irrigation
: water put in by irrigation and rainfall
Start counting water at land preparation or at crop
establishment
Water productivity (WP)
Water productivity
(kg grain m-3 water)
Rice
Dryland cereal
Per transpiration (T) 1
up to 2
wheat: up to 2
Per evapotranspiration (ET) 2
0.6-1.6 (1.1)
wheat: 0.6-1.6
maize: 1.1-2.7
Per inputs by rain and
irrigation (RI) 2
0.2-1.2 (0.4)
1:
measured in pots
2 : measured in fields
5
2.2-2.4
0.0-0.1
0.1-0.2
0.2-0.3
0.3-0.4
0.4-0.5
0.5-0.6
0.6-0.7
0.7-0.8
0.8-0.9
0.9-1.0
1.0-1.1
1.1-1.2
1.2-1.3
1.3-1.4
1.4-1.5
1.5-1.6
1.6-1.7
1.7-1.8
1.8-1.9
1.9-2.0
2.0-2.1
2.1-2.2
2.2-2.3
2.3-2.4
2.4-2.5
5
2.0-2.2
1.8-2.0
1.6-1.8
1.4-1.6
1.2-1.4
1.0-1.2
0.8-1.0
0.6-0.8
0.4-0.6
0.2-0.4
35
0.0-0.2
35
Frequency (%)
30
Zwart and Bastiaans, 2005
25
20
15
10
WPET
0
Frequency (%)
Tuong, Bouman, Mortimer, 2005
30
25
20
15
10
WPIR
0
Some conclusions
• Rice plant same WPT as other C3 cereals
• Rice field same WPET as other C3 cereals
Variation in WPET caused by variety, climate, management
• Rice field requires 2-3 times more water than other cereals,
mainly because percolation and seepage losses (25-50% in
heavy soil with shallow groundwater, to 50-85% in lighter soils
with deep groundwater)
• Percolation and seepage are/can be reused downstream
Pressure to produce more food (rice) is getting
greater because of ever increasing population
But also:
More people want
• more industry
• more drinking water
• more cities
• more swimming pools
• more….
=> Water is getting scarce and expensive
 Need to develop technologies to help farmers
cope with water shortage (ie, not enough water to
keep rice fields continuously flooded)
Water-saving technologies

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