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

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’

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’

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

{

{

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

{

{

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

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

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

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

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

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.”

“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

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).

World Bank-100M$

IFAD-47M$

AfDB-250M$

OPEC-35M$

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

• Mulching

Reduction in non-beneficial

consumption (Es/Tw) ≈ 20-30%

• Weeding

•Sub-surface irrigation

Decreasing Es & Tw

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) {

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

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

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.)

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

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

http://neareast.fao.org

Thank You