1. Session 1:
Ag Water Management
planning
Robyn Johnston
Photo:cc: Andrew Beirne
March 19, 2013
Photo: David Brazier/IWMI
IWMI-ACIAR workshop
Phnom Penh
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2. IWMI team
• Robyn Johnston
• Sanjiv de Silva
• Elizabeth Weight
• Martina Macarenhas
• Thuon Try
• Terry Clayton
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3. Contributors
• Department of Agricultural Extension (lead by Dr
Mak Souen)
• Royal University of Phnom Penh (lead by Heng
Nareth and John Pilgrim)
• Sonali Senaratana Sellamuttu
• Soraya Nour
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4. Objectives of the Session
• What are the best investments to make in
agricultural water management (AWM)
– To alleviate poverty / increase food security?
– To increase rice production?
Later sessions on
• What institutions are needed? – Session 2
• What are impacts of agricultural intensification on
environment (particularly fisheries)? – Session 3
• What is the role of groundwater? – Session 4
Water for a food-secure world
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5. Context - changing approaches to AWM
• IWMI - FAO 2010 study Trends in Asian irrigation
• IWMI – Gates 2012 study on AgWater Solutions
• RGC National Strategy for Agriculture and Water
• ADB 2010 reviews of project outcomes and 2012 report on
Rural Development for Cambodia Photos: Thuon Try
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6. IWMI – FAO 2010
Revitalising Asia’s Irrigation
• Trends in Asian irrigation
– Large-scale surface irrigation is shrinking or
under-performing
– Small-scale pumped irrigation (surface and
groundwater) is booming- “water scavenging”
– PIM and IMT initiatives have not lived up to
expectations
– New approaches to improve flexibility and
reliability of supply and increase productive
use of water
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7. IWMI – Gates Foundation 2012
AgWater Solutions
• AWM in Africa, India
– Small-scale AWM is outpacing large-scale
formal irrigation in area and value of
production, driven mainly by individual farmer
investments
– Diverse set of AWM approaches targeted to
specific contexts
– Expansion of unregulated small-scale irrigation
poses new challenges
– Strategic investments are needed to support
existing, farmer-driven trends
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12. National Strategy for Agriculture
and Water 2010 - 2013
Output E: Water Resource Management and Agricultural
Land Management
• IWRM plans for Tonle Sap and connected river basins
• Land and water resources inventory; master plans for identified AWM
priorities
• 100,000 ha of wet season and 25,000 ha dry season irrigation per
year is constructed
• Local involvement in IWRM and irrigation infrastructure planning
• Sustainable water management, harvesting and use practices are
adopted by farmers
• Drought and flood forecasting system and mitigation measures
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13. ADB 2010
• A new approach is needed to supporting water
resources management in Cambodia. The scope for
identifying conventional large irrigation projects is limited
and the low level of past success indicates a range of
problems. Other more innovative approaches which
more carefully fit the characteristics of the country need
to be developed, including smaller scale simple water
resource management projects that are easier to
implement.
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14. Irrigation policy in Cambodia
• Irrigation / AWM is a critical input for agriculture to
– Reduce poverty and improve food security
– Increase rice production and exports
• MOWRAM 2012
– USD 260 million in ongoing projects for irrigation /
AWM (loans and grants)
– USD 868 million committed, mainly for large scale
infrastructure
• eg $200 million Vaico project recently announced
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15. Different policy drivers,
different outcomes and focus?
Rice for export Poverty / food security
• Commercial / agroindustry - • Semi-subsistence (only 35%
larger farmers; produce surplus)
• Dry season paddy, full • Early / late wet season rice or
irrigation non-rice, supplementary irrigation
• Intensification • Diversification
• Large scale formal irrigation • Small-scale informal irrigation
and AWM
• Major investments – loans and • Limited funds, mainly small scale
grants / FDI (private sector and NGO and donors
development partners)
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17. 1. Wet season rice and food security
• Existing formal irrigation system in Cambodia
– 0.76 m ha wet season; 0.36 m ha dry season (MAFF 2012).
• Wet season irrigation reduces risk of crop loss, but has little
impact on rice yields (Wokker et al 2011; Halcrow 1994; IRRI 2012)
– increases in yield of WS rice in last 20 years are mainly from
improved varieties and fertilizer use
– farmers unwilling to pay ISFs, maintenance
– losses to flood are 3-4 time greater than losses to drought
• Protecting wet season crop is high priority for food security
– Are formal irrigation schemes the most effective way to do this?
– Would small-scale pumping / on-farm storages be more efficient?
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19. 2. Double cropping for poverty alleviation
• Double cropping is important for food supply and income
• Uptake of double cropping is limited in many formal IS
– unreliable and inflexible water delivery
– IS designed for rice do not adapt well for other crops
• Successful double cropping from small scale pumping
and small storages (farm ponds, small lakes, streams)
– short period crops (rice or non-rice) in early or late wet season
with supplementary irrigation
• Enabling farmers to grow two crops a year requires
change in the way formal schemes are operated, and /
or a shift to individually managed irrigation.
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21. 3. Dry season rice production
• Full irrigation of dry season rice is high input, high return
– Around USD 800 / ha in improved seeds, fertilizer, and pesticides to
stabilize yields at 5-6 t/ha
• Dry season rice production is trending to commercial
– most farmers growing dry season rice have larger holdings, and
mechanization is increasingly common
– poorer farmers can’t afford inputs or take risk
• Could more commercial approach to DS rice irrigation result
in different modes for management and water delivery?
• How can investment be structured to allow the less affluent
farmers to participate in DS rice production?
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22. Is a focus on rehabilitation of existing
schemes impeding progress?
• Two thirds of existing irrigation schemes in Cambodia are
not operational
– CEDAC (2009) found that of 2525 schemes, only 6% were
functioning well and 62% were not functioning.
• Large investment in repair and rehabilitation of gravity fed
canal systems
– widespread failure of rehabilitated schemes after 1-2 years
– attributed to lack of maintenance, flood damage and poor operational
practices
BUT – are these really the problem?
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23. http://www.cambodiaatlas.com/map
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24. Is a focus on rehabilitation of existing
schemes impeding progress?
• 80% of the irrigation schemes existing after 1978 were built
during 1975-8
– plan for leveled 1 ha plots fed by canals in a 1x1 km grid
– built without consideration of overall water requirements or
availability, soil suitability, siting or design of structures
• Many schemes have flawed design, poor construction and
inappropriate siting and will never be feasible
• Distract from rational planning and design
– expectation that irrigation can be extended to all major rice areas;
– gravity-fed canal command irrigation as the norm.
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25. Physical constraints to irrigation
• Flat topography of the lowland plains means few
locations for reservoirs
– <15% of major rice areas are capable of controlled irrigation
based on reservoirs (Halcrow 1994)
• Strong seasonality of flows constrains river pumping
– large pumping heads as river levels fall up to 10 m
• Annual inundation of the floodplain
– infrastructure is flooded, with resulting damage and silting up of
canals, gates and storages, adds to O&M costs.
• Poor soils in half of agricultural areas (White et al 1997);
– sandy, low in nutrients, low potential for yield improvement
– irrigation in these areas is likely to be uneconomic
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26. • Irrigation in Cambodia needs targeting to local conditions
– No “one-size fits all” solutions
• Capitalise on “natural infrastructure”
– floodplain lakes and wetlands (seasonal storage)
– rivers and alluvial aquifers (storage and transmission)
• Shift towards informal pumping is underway
– Surface water and groundwater
– “water-scavenging” irrigation pattern seen in much of the rest of Asia
– advantages in flexibility and individual control over water access
• New set of challenges in water management
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28. Questions for discussion
• What are the most effective means of delivering water for
– Wet season rice
– Small scale double cropping / diversification
– Dry season rice/ intensification (commercial)
• How does this differ between different regions / areas?
• What kinds of support and investment are needed for each
of these?
• What are the main drivers and obstacles?
• How can we move this discussion forward?
– Who should be involved?
– How do we involve them?
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