1 Sustainable Water Management of Paddy Fields In Adapting to Climate Change Dr. Shen-Hsien Chen International Society of Paddy and Water Environment Engineering.
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Sustainable Water Management of Paddy FieldsSustainable Water Management of Paddy FieldsIIn Adapting to Climate Change n Adapting to Climate Change
Sustainable Water Management of Paddy FieldsSustainable Water Management of Paddy FieldsIIn Adapting to Climate Change n Adapting to Climate Change
Dr. Shen-Hsien Chen
International Society of Paddy and Water Environment Engineering (PAWEES)
March 18, 2009
SpeakerSpeaker’’s Corners Corner
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Outline Outline
I. Introduction to PAWEESII. Impact Assessment of
Climate Change on Paddy and Water Environment
III.Adaptation Strategy to
Mitigate Impacts
IV.PAWEES’s Contributions in
Water Management of
Paddy Fields
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I. Introduction to PAWEES
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EstablishmentEstablishment Initiated by Japan, Korea, and Taiwan
Established in January 2003, just prior to WWF3
MissionMission Build and distribute a new system of science and technology
in agricultural engineering
Deal with water issues linked to the environment, food security, and poverty
2008 PAWEES Conference2008 PAWEES Conference
Theme: Impact assessment and adaptation strategy of paddy & water management due to global climate change
International Society of Paddy & Water International Society of Paddy & Water Environment Engineering (PAWEES)Environment Engineering (PAWEES)
I. IntroductionI. Introduction
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II. Impact Assessment of Climate Change on Paddy and Water Environment
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Changes of climate (e.g., air temperature, precipitation, and evapotranspiration) would have direct effects on rice plant growth.
They would also cause hydrological pattern changes of an area or basin with paddy fields.
The impacts on paddy & water environment are believed to have complicated processes so that they are difficult to be assessed precisely.
Although the impacts might be different from place to place, they have been indeed observed more and more.
Climate Change and its impacts on Paddy and Water Environment
II. ImpactII. Impact AssessmentAssessment
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Japanese CaseA study was conducted to assess the future possible
changes in rice cultivation in the 2070s.
The results show that the mean yield and total production of rice would increase in years with cool summer, while decrease with hot summer.
II. ImpactII. Impact AssessmentAssessment
Korea CaseA study was conducted to assess the future
potential impact of climate change on the inflow from agricultural watershed and its temporal variation of reservoir storage in 2020s, 2050s, and 2080s.
The results show that the future decreased inflows
in autumn would affect the reservoir storage during the period of autumn and winter, and cause a severe spring drought if rainfall is insufficient.
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1154mm1154mm 1657mm1657mm
1056mm1056mm
y = 0.0773x - 132.87
0
5
10
15
20
25
30
35
1961 1966 1971 1976 1981 1986 1991 1996 2001 2006
Year
Rain
fall Inte
nsity(m
m/d
ay)
Rainfall Intensity
Linear Fit
II. ImpactII. Impact AssessmentAssessment
0 1 2 3 4 5 6 7 8 9 10
1951-1960
No. of years
3.1
3.2
2.9
3.4
3.3
6.9
Average annual times
< 3 times/yr 4times/yr 5times/yr 6times/yr
7times/yr 8times/yr 10times/yr
1961-1970
1971-1980
1981-1990
1991-2000
2001-Sep. 2008
0 1 2 3 4 5 6 7 8 9 10Average times
Times of typhoons attacked Taiwan from 1951-2008
Rain
fall inten
sity
Year
Trend of rainfall intensity for Keelung Station in Taiwan from 1961 to 2006 Daily and cumulate rainfalls in the
plum rains season from 1989 to 2006
Taiwan Case Some observed changes of
hydrological cycle do match the expected impacts of climate change.
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Taiwan Case (cont’d) The irrigation of paddy rice for first crop duri
ng dry season needs more water than second crop during wet season.
The shortage of rainfalls in dry seasons has had a significant impact on the first crop of paddy rice in Taiwan.
Fallow of paddy fields for supplying agricultural water to domestic users even makes the situation worse.
In adapting to climate change, the first crop of paddy rice should be considered to adopt other up-land crops, such as corn, soybean and sweet potatoes, to conserve the scarce water in dry season for other high productivity uses.
II. ImpactII. Impact AssessmentAssessment
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III. Adaptation Strategy to Mitigate Impacts
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III. AdaptationIII. Adaptation StrategyStrategy
Adaptation Strategies to Mitigate the Impacts (1)
Assess: Assess the most vulnerable areas of paddy fields and periods of
cultivation to climate change impacts
Re-evaluate: Re-evaluate the resistance or supply ability of existed
agricultural water infrastructures and determining if they needed to be
functionally rebuilt and expanded
Minify: Create diversified, distributed, and shock-flexible units and
backup systems.
ARMING for Climate Change!
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III. AdaptationIII. Adaptation StrategyStrategy
Adaptation Strategies to Mitigate the Impacts (2)
Implement: Select, prioritize, and phase implementation of specific
adaptation strategies
No-regret: Reduce, stop, or even avoid the actions assured to result in
hazards to paddy and water environment, and keep or even enhance those
benefit systems
Gather: Gather all stakeholders’ opinions and make the best decision
ARMING for Climate Change!
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IV. PAWEES’s Contributions in
Water Management of Paddy Fields
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農業地帶
排水水路
Evapotranspiration• Increase probabilities of rainfall• Regulate microclimate
Percolation• Purify water quality• Collected to provide the
source of return flow
Return Flow• Reuse to provide for
other users
Domestic use
Industrial use
Agricultural use
Detention• Retain significant amount
of irrigational water or floodwater by deep water management or deep ponding (Japan)
IV. PAWEES’sIV. PAWEES’s Contributions Contributions
Novel Concept:Novel Concept: Multiple functions of Paddies Multiple functions of PaddiesNovel Concept:Novel Concept: Multiple functions of Paddies Multiple functions of Paddies
Phorizontal >>Pvertical (Korea)
Paddy fields
15
6 cm
Regular Application
New Application
18 cm25 cm
Topic 1: Deep Water Management (1)Topic 1: Deep Water Management (1)Topic 1: Deep Water Management (1)Topic 1: Deep Water Management (1)
Advantages: In terms of water storage aspect, extra water obtained can be stored
in paddy fields as well as underground aquifers. In terms of flood detention aspect, lots of paddy fields with taller
border means more space for detaining or storing floodwater. In terms of paddy production aspect, deeper water can protect stem
of paddy from storms, and the quality and productivity of paddy rice are almost the same as and even better than those in the past.
Playgrounds, green spaces, schools, etc.
Watershed
Paddy fields
IV. PAWEES’sIV. PAWEES’s Contributions Contributions
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Demand for raw water
Demand for water of good quality
Paddyfields
Natural river or drainage(non-guaranteed water quality) Treatment
plant
Cut-off gate
Externally Discharge sewage is strictly prohibited
Users
Topic 2: Agricultural Return Flow (1)Topic 2: Agricultural Return Flow (1)Topic 2: Agricultural Return Flow (1)Topic 2: Agricultural Return Flow (1)
Separated ditch for collecting return flow
Pond for storage
Users
IV. PAWEES’sIV. PAWEES’s Contributions Contributions
Drainage ditches
Irrigational ditches
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IV. PAWEES’sIV. PAWEES’s Contributions Contributions
Topic 2: Agricultural Return Flow (2)Topic 2: Agricultural Return Flow (2)Topic 2: Agricultural Return Flow (2)Topic 2: Agricultural Return Flow (2)
Conventional way-- “Differential”
Distribute supply to the sectors with demands
Source of supply
Conveyance system
Distribution system
Domestic water users
Agricultural
water users
Domestic water users
Industrial water usersDrainage system
Return flow
Specify the nearest supply based on integrated demands
New concept-- “Integral”
Paddy field
Paddy field
Advantages:Better water quality because of paddy purificationLow costs of conveyance systems because of short distanceLess argument among sectors because of return flow of paddy fieldsMore flexibility of allocation because of stable return flow
Successful application in “Midori” of Japan
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Sea
Shallow subsurfacehorizontal percolation
Paddy field
Sludge wall in plow zone
Arable Land
Salty water vapor
Windbreak forest
Coast N
Field in Taiwan
IV. PAWEES’sIV. PAWEES’s Contributions Contributions
Sludge SludgeSludge
Windbreak trees
Topic 3: Land Conservation Strategy (1)Topic 3: Land Conservation Strategy (1)Topic 3: Land Conservation Strategy (1)Topic 3: Land Conservation Strategy (1)
Without irrigation
PaddiesAugust, 2008 March, 2009
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Shallow subsurfacehorizontal percolation
Wetland Paddy
Sludge wall in plow zone
Windbreak forest
Without irrigation
N
IV. PAWEES’sIV. PAWEES’s Contributions Contributions
Lake Chad Basin Sahara
Airborne dust
Chad, Africa
Topic 3: Land Conservation Strategy (2)Topic 3: Land Conservation Strategy (2)Topic 3: Land Conservation Strategy (2)Topic 3: Land Conservation Strategy (2)
Reduced Lake Chad
Sahel Area
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Creek irrigation in Japan (for over 300 years)
Arable land in Lake Chad Basin
Map source: http://www.google.com Map source: http://web-japan.org
“Furrow Recharge Technique”(Japan)- Widen and deepen the drainage ditches to
collect more percolation from the bottomPaddy field
Irrigational ditch
Drainage ditch
Prospect of Chad in the future
Crop Rotation in Taiwan (for 80 years)
Topic 3: Land Conservation Strategy (3)Topic 3: Land Conservation Strategy (3)Topic 3: Land Conservation Strategy (3)Topic 3: Land Conservation Strategy (3)
Current
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Thank you for Listening!
Paddy field in Taiwan
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