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?

Part 2:

What are ecosystem services and how

do they link to water for food?

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?

Part 3: How do you value ecosystem

services in water for food?

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