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UNESCO-IHE Institute for Water Educationwww.unesco-ihe.org
Beyond more crop per drop
An ecosystems perspective to water productivity
Webinar 24 March 2016
Charlotte de Fraiture
Presentation outline
1. Why water productivity and how do you measure it?
2. What are ecosystem services and how do they link to
water for food?
3. How do you value ecosystem services in water for food?
4. What does this all mean for water productivity?
Part 1: Why is water productivity
important and how do you measure it?
• Policy objective: increase water productivity by 25%
• Why: agriculture is the biggest water user worldwide.
• Water is getting scarce but not used efficiently.
Part 1: Why water productivity; how do you measure it?
• Water productivity = Crop water
productivity (kg/m3)
– More crop per drop
– Remote Sensing (previous
speakers)
• Water productivity = More
income per drop ($$/m3)
– Mixed cropping & multiple use of
water (fish, domestic)
• More jobs per drop = economic
impact of water use in agriculture
Water flows, moves through the basin
• Unintended
by-effects (externalities)
• Use of water in one part affects other parts of basin,
positively
or negatively
Drawing by Olivia Molden
Part 1: Why water productivity; how do you measure it?
Examples of negative externalities of water for food
- Drying of rivers
- Degradation of wetlands
- Pollution (agri-chemicals)
- Salinization
- Groundwater depletion
Part 1: Why water productivity; how do you measure it?
Examples of positive externalities of water for food
+ Drainage water reuse by d/s users
+ Recharge of groundwater
+ Flood retention
+ Esthetic values
Multi-functional landscapes
Part 1: Why water productivity; how do you measure it?
Question:
Potentially what are the positive and negative effects
of the use of water in this paddy field?
Ecosystem services = benefits to humans
provided by natural ecosystems
Examples: food, fish, timber, flood
retention, nutrient recycling, recreation
Ecosystems services
• Provisioning – provide products
• Supporting & regulating – natural processes
• Cultural / recreational / esthetic
Part 2: Ecosystem services and their link to water for food
wetland
weir
12 km upstream from Colombo cityAfter a heavy (but not
unusual) rainstorm
Example from Colombo
Part 2: Ecosystem services and their link to water for food
• Urban area is expanding
• Pressure on land and water resources
• Rice is low value – low crop per drop
• Flood retention & recreational functions very valuable
Part 2: Ecosystem services and their link to water for food
Example from Colombo
Discussion:
• If you just consider rice production, the water productivity
is very low. The low value use of land and water
resources around an expanding city for staple crop
production could be considered inefficient.
• However, if you consider the flood retention function and
the potential damage due to increased flooding, keeping
paddy fields make a lot of economic sense.
• However, farmers do not reap the benefit of preventing
flooding and may be better off selling their land to
developers.
• How could you factor this in?
Potential ecosystems services provided by irrigated
agriculture
• Provisioning services – crops & jobs, fish, herbs
• Groundwater recharge – seepage
• Reduce soil erosion - terracing
• Flood retention
• Supporting biodiversity
• Carbon sequestration and mitigation, GHG reduction
1. Production value – provisioning services
For example: kilogram of crop per
unit of irrigation water applied or
consumed
Part 3: How do you value ecosystem services in water for food?
2. Costs estimation of damage undesired effects
Example 1: Cleaning costs of polluted water
(New York - costs of treatment facility)
Example 2: cost of flood damage (Colombo example)
Part 3: How do you value ecosystem services in water for food?
23
3. Estimation of cultural & recreational values
Willingness to pay (or willingness to accept):
For example: comparing house prices with and without
view, travel costs to touristic places, survey asking
people
Part 3: How do you value ecosystem services in water for food?
Some examples from irrigated rice cultivation
• Xiao et al. (2011) estimate that the economic value of ecosystems services provided by paddy fields in China exceed the value of rice production by a factor of 3 to 8.
• Natuhara (2013) estimates the value of services that regulate ecosystem functions derived from irrigated paddy fields in Japan at US$ 72.8 billion.
• Liu et al. (2005) estimate that seepage from paddy fields accounts for 40% of groundwater recharge in Taiwan, with an economic valued of nearly 60% of the value of the paddy production.
• By installing flood control devices in existing paddy fields in one district in Japan, the flood damage caused by 50-year return period rainfall event was reduced to that of 10-year return period rainfall event (Yoshikawa et al., 2010).
Part 3: How do you value ecosystem services in water for food?
Should we rethink water productivity to include
ecosystems services?
More crop per drop More dollars per crop
More jobs per drop More benefits per drop
(including services to the environment)
4. Beyond crop per drop: incorporating ecosystem services in water productivity
Implications for policy goal of increasing water productivity by 25%?
UNESCO-IHE Institute for Water Educationwww.unesco-ihe.org