Technical Seminar “Water Efficiency, Water Productivity, Water Saving" , by: Pasquale Steduto This topic is part of the Water Scarcity initiative (WSI)’s debate to clarify the confusion between concepts and terminologies related to water management that impede sustainability of this natural resource. FAO tries with the WSI to open the discussions on water allocation and water accounting.

1. Water Efficiency
Water Productivity
Water Saving
Pasquale Steduto
Deputy Director FAO Office
Near East and North Africa
Cairo, Egypt
The mix-up impeding progress towards
Water Sustainability
Cairo - Egypt, 16 September 2015

2. Water Efficiency
In general terms Water Efficiency (e) refers to the ratio
between water used by a ‘user’ for a give purpose to
the water applied to that same user
Irrigation Efficiency (ei)=
water used by a crop field as ET
water applied to the field
e is ‘a-dimensional’, has ‘theoretical limits’ (0-1) and deals with
‘liquid phase’

3. Water Productivity
In general terms Water Productivity (WP) refers to the
ratio of the net benefits from crop, forestry, fishery,
livestock, or mixed agricultural systems to the amount
of water used as ET to produce those benefits
WP =
benefits produced
water used as ET
‘benefits’ can be: biomass; yield; Kcal; proteins; income; jobs; etc.
WP is ‘dimensional’ (kg m-3; $ m-3; jobs m-3) , is not confined to
the ‘theoretical limits’ 0-1 and deals with ‘gaseous phase’

4. Water use
Water Saving
What water saving refers to ?
We need a water accounting framework to make sure
we know what we are talking about
Consumptive
(gaseous phase)
Non-consumptive
(liquid phase)
Beneficial (TC)
Non-beneficial (ES/Tw)
Recoverable (return flow)
Non-recoverable
{
{

5. Now we know that water saving refers to the water
that would be otherwise no longer available to the
system under consideration (spatial-scale issue)
Water use
Consumptive use
Non-consumptive use
Beneficial (TC)
Non-beneficial (ES/Tw)
Recoverable (return flow)
Non-recoverable
{
{

6. Example 1
1 ha 1 ha
5,000 m3 5,000 m3
e= 100%
5,000 m3
ET
5,000 m3
ET
5,000 m3
10,000 m3
1 ha
e= 50%
5,000 m3
ET
Y=100 ton
Total water use = the same
Total water consumed = doubled
Production = doubled
Less efficient water use More efficient water use
Benefits: More production
Less pollution
e, WP and Water Saving

7. Example 2
Less water-productive crop More water-productive crop
Benefits:
Higher yield
5,000 m3
5,000 m3
1 ha
WP= 20 kg m-3
ET
Y=100 ton ha-1
Total water use = the same
Total water consumed = the same
Yield = higher
5,000 m3
5,000 m3
1 ha
WP= 24 kg m-3
ET
Y=120 ton ha-1

8. Example 3
• Total water used
reduced
• Total water
consumed
the same
• Return flow
reduced
Benefits:
Less pollution
More water stream
Less infrastructure
• Yield the same
Less efficient water use More efficient water use
Crop ET=56 units Crop ET=56 units
44
UNITS
44
UNITS
100
UNITS
100
UNITS
20
UNITS
38
UNITS
Return Flow
24 UNITS
Return Flow
6 UNITS

9. Example 4
Less efficient water use More efficient water use
Total water use reduced
Total water consumed the same
5,000 m3
1 ha
ea= 100%
0 m3
5,000 m3
ET
Benefits:
Less energy
Less pollution
10,000 m3
1 ha
ea= 50%
5,000 m3
5,000 m3
ET
Y=100 ton ha-1
Yield the same

10. Key messages
1. Strictly speaking water saving does not come from
higher irrigation efficiency or higher water productivity,
but from reducing the consumptive use and the non-
recoverable fraction of the non-consumptive use of
water
2. Improved irrigation efficiency and water productivity
are beneficial to farmers but not necessarily to water
resources managers concerned with water saving
3. To achieve water saving there is a need to first setting
the limit of ‘water allocation’ and then use any measure
to increase ‘efficiency/productivity’ of water through the
adoption of a solid water accounting framework

11. The confusion
Upon receiving the news, Igal Aisenberg, Netafim President & CEO said,
“We are truly honoured to receive the Stockholm Industry Water Award.
As the global pioneer and leader in drip irrigation, we have always focused on
saving water. With water and land scarcity topping the list of today’s major global
challenges, we’re leveraging our expertise and experience in drip technology to help
combat food price inflation, ensure food security, and achieve water sustainability.
This prestigious award is testimony to our efforts and inspires our work to continue
to help reduce water usage and make the world a better, more sustainable place.”

12. “To counter the challenge of booming water demand we must manage it in a far
smarter way. It concerns our lives and our livelihoods. In five years I want us all in
our daily lives to be as aware of water efficiency as we are of energy efficiency today”
Mr. Torgny Holmgren, Executive Director of Stockholm International Water Institute,
told the closing session.
2014

13. Analysing the study, it came out that ‘consumptive and non-
consumptive’ water use were added together and that only
10-30% of these 14 Million acre-feet were actual savings in
consumptive use (the non-consumptive use was recoverable).

15. World Bank-100M$
IFAD-47M$
AfDB-250M$
OPEC-35M$

16. In Open Fields
• New varieties
• Drip irrigation
Potential ea ≈ 90%
With poor management
ea ≈ 50%
Increasing WP & e
Reduction in non-beneficial
consumption ≈ 0-10%
Some solutions

17. • Mulching
Reduction in non-beneficial
consumption (Es/Tw) ≈ 20-30%
• Weeding
•Sub-surface irrigation
Decreasing Es & Tw

18. In Closed Systems
• Non-consumptive use ≈ 0
• Hydroponic Greenhouses
• ET ≈ -20-30%
• Less Rs, Turbulence and VPD
Technology & knowledge
intensive (high management)
New Generation
Green Houses
Recycled
Reused
}Consumptive use
Beneficial (TC)
Non-beneficial (ES/Tw)
{

19. New Generation Green Houses
Reduction up to 90% of water consumption
48°C
41°C
38°C
39°C
50°C
hot
warm
cold
1
2
4
5
6
3

20. The ‘rebound’ effect
The “rebound effect” is also known as Jevons Paradox
In 1865, the English economist William Stanley Jevons
observed that technological improvements that
increased efficiency of coal-use led to the increased
consumption of coal in a wide range of industries
While common intuition suggested that if less of a
particular input was required to achieve a given
output, the demand for that input would fall (and thus
its price), the observed reality was that with the fall in
price of the input, its demand increased

21. The simple rules for
Water Sustainability
Water
Accounting
Setting the
limits of
consumption
Adopt all measures to
maximize the benefit of
each drop of water
(sources, users, consumptions, re-uses)
(overall, by allocation;
balancing water in&out)
(e, WP, HiTech, governance, etc.)

22. Closing Remarks
Water saving does not relate to irrigation efficiency or
crop water productivity but to water consumption and
to the non-recoverable fraction of water use
Water accounting at basin level and on the whole arable
land (particularly under irrigation) is key to water saving
The more we can manage the environment where crops
grow, the more we can control water consumption. In
fact, hydroponic greenhouses have the potential for the
highest efficiency, productivity and saving of water

23. To obtain water saving towards sustainable water
resources management, sequencing of measures is key:
control of water consumption must precede on farm
interventions
The economic benefits of hi-tech irrigation tend to
make water more valuable to farmers so that they
continue to demand more water
The mix-up between efficiency, productivity and saving
of water is impeding progress towards water
sustainability and proper strategic planning

24. http://neareast.fao.org
Thank You