Can Water Productivity
Improvements Save Us From
Global Water Scarcity ?
25 February 2020
CIHEAM-Bari
Winston Yu, Stefan Uhlenbrook, Rachel von Gnechten

Numerous factors are contributing to increased global
water scarcity. This raises concerns whether there will be
enough water for all uses and particularly for food
production.
Water productivity interventions have been implemented
in response to water scarcity.
Assessing effectiveness is complicated by:
• Multiple objectives (sometimes competing)
• Multiple perspectives and scales
• Terminology
• Data and evidence

Defining water use
Consumption
ApplicationWithdrawal

Water productivity refers to the ratio of the
benefits from agriculture systems to the amount
of water used to produce those benefits
Numerator or
denominator term
reflects water source
(rainfed versus irrigated)
“more crop per drop”
Physical [kg/m3] Economic [USD/m3]
Value derived per
unit of water used
Other

Irrigation efficiency reflects the percentage of
water used in irrigation
Classical irrigation
efficiency
Water-use
efficiency
Effective irrigation
efficiency

Wide range of water productivity interventions, and not
all directly address water scarcity
Breeding and
biotechnology practices
Precision application
practices Production practices
Soil practices Water delivery practices
Water management
practices

Water productivity interventions have different
objectives at different scales and for different users

Water productivity interventions are often branded
for their water “savings” and improved irrigation
“efficiencies”
• “Efficiency” carries the implication that the “increase in efficiency
actually saves some of the resource” (Jevon’s paradox)
• Advanced irrigation technologies that increase ET can actually
increase on-farm water consumption
• Farmers switch to more water-intensive crops, expand
production, or see “a strong marginal yield response from
additional water” with the same crop (Grafton et al. 2018)
• Irrigation efficiency paradox
• Under what circumstances would real water “savings” still occur?
• Food produced at a farmer’s increased irrigated scheme
(enlarged through higher field irrigation efficiency) does not
need to be produced elsewhere and, thus, water can be saved
in a different basin.

Water accounting terminology

Many case studies reveal that water “savings” at the
farmer-scale may not translate to water “savings” at
the larger basin scale.

Water Saving Technologies: Myths and Realities Revealed
in Pakistan’s Rice-Wheat Systems (IWMI RR#108)
Background
• Objective: Assess the impact of “resource conservation” practices on water
application, water productivity and real water savings
• Location: Rechna Doab, semi-arid Punjab Province, Pakistan

Ideally, the water
received in the field
would be used as
transpiration to
support crop
growth.
Some of these
fluxes do not do
this.

Do these fluxes go to places that can be pumped or otherwise
re-used by the same or downstream farmers OR do they go to
degraded sinks?

At field scale: Water application reduced
At field scale adoption of resource conservation technologies led to
• 24-32% reduction in water application at the field scale
• Increased farm level incomes

What does an increase in cropping intensity mean?

At system scale: Water consumption increased
Ahmad et al. 2007
Overall water consumption at the system scale increased by 59 million
cubic meters/year following the adoption of “resource conservation”
technologies.

Reductions on water
applications at the
field scale translate
into reduced water
consumption in the
system (i.e., farmers
won’t use the
“saved” water).
Net farm incomes
increased.
Increased profitability
incentivized farmers to
expand cultivated
area and/or increase
cropping intensity.
Belief Reality

Topics to discuss during the workshop
• Multiple objectives and motivations for adoption of
different water technologies
• “Improving water productivity is not a goal in and of
itself” (Giordano et al. 2017)
• Need to evaluate at the crop, field, farmer, basin, and
regional scales
• “There are rather few examples of carefully documented
impacts of hi-tech irrigation” (Perry et al. 2017)
• Need accepted, unambiguous terminology
• Understand the (mis)conceptions of commonly used
terms, such as water “savings”
• What do “successful” interventions to deal with
water scarcity depend on?

Thank You