REPLY: EFFICIENT IRRIGATION; INEFFICIENT COMMUNICATION;FLAWED RECOMMENDATIONS: RESPONSE TO COMMENT

CHRIS PERRY�

WaterWatch, Wageningen, the Netherlands

First, I welcome the constructive approach taken in these comments. However, Naim makes an important error in

his first line in stating that this is ‘‘essentially an irrigation paper’’. The abstract of the paper includes the following:

‘‘Based on the work of various previous writers, an analytical framework and associated terms are proposed to

better serve the needs of technical specialists from all water-using sectors, policymakers and planners in

achieving more productive use of water and tracing the implications of interventions on other uses and

users.’’ (emphasis added)

So the objective here is not sector-specific, and this bears strongly on much of my response – in particular, to the

issue of ‘‘Effective Efficiency’’ – but it is important at the outset to stress that a broader audience is targeted.

Naim states (his Para 2A – all subsequent comments are referenced according to his paragraph numbering):

‘‘The paper puts Classical Efficiency into spotlight by making it clear through various evidences that it does

not work and gives flawed recommendations. This is indeed true.’’

With that agreed, much progress is already evident.

Indeed, I only find substantive disagreement with the thrust of the original paper in two areas. Perhaps the

presentation is less theoretical than an academic might prefer (hence the recommendation ‘‘one needs to develop a

sample population of evidences, make a hypothesis and test its significance by an appropriate statistical test’’) but

the paper is aimed at practitioners and draws on practical examples. If some research funder is willing to support the

proposed research, then perhaps a suitable framework for testing the hypothesis can be formulated. I am already

pleased that we agree, as stated above, that ‘‘Classical Efficiency . . . does not work and gives flawed

recommendations’’.

The two substantive areas that are taken up in some detail by Naim are inadequate specification of basin

efficiency, and failure properly to address the Effective Efficiency approach (I note that David Seckler and Andy

Keller are acknowledged for their contributions to the note.)

So first, basin efficiency:

As I understand it, just as Classical Efficiency is the ratio of water used by the plant to water diverted, Basin

Efficiency is the ratio of water consumed to total water available in the basin (which may be in terms of total

precipitation plus transfers, or just runoff . . .). I have always thought the term meaningless because as with ALL

uses of the term efficiency we have the implication that higher is better.

It is not. Based on this indicator the Aral sea basin would have an ‘‘efficiency’’ in excess of 100%, and is

described (rightly) as in crisis. Indeed any basin where outflow is zero for thewhole or important parts of the year is,

at least, 100% ‘‘efficient’’ and most would agree that a decline in ‘‘efficiency’’ would be a very good thing. Are

IRRIGATION AND DRAINAGE

Irrig. and Drain. 57: 249–252 (2008)

Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/ird.423

*Correspondence to: Chris Perry, WaterWatch, Generaal Foulkesweg 28,Wageningen 6703 BS, the Netherlands. E-mail: chrisjperry@mac.com

Copyright # 2008 John Wiley & Sons, Ltd.

there other efficiency terms where we should be striving for reductions? Electricity transmission, mechanical

efficiency of a gearbox, central heating boilers? I think not, because in these areas efficiency means what it says.

While trying to find a definition of basin efficiency (David Seckler once suggested a sort of economic basis of

maximising economic benefit of basin resources) I came across the following report title and abstract:

Water Use Efficiency at the River Basin Scale: Implications for Hydrologic Science and Water Management

Policies

Ximing Cai

International Food Policy Research Institute (IFPRI), International Water Management Institute (IWMI).

2033 K. St. Washington DC 20006

Although the classical irrigation efficiency concept is appropriate for irrigation system design and

management, it could lead to erroneous conclusions and serious mismanagement of scarce water resources at

a larger scale. This is because the classical approach ignores the potential reuses of irrigation return flows. To

overcome these limitations, researchers have proposed the concept of water use efficiency at the basin scale,

or basin efficiency, which takes into account the potential recycling and reuse of return flows.

So here we have an author actually trying to clarify the confusions arising from basin efficiency who ends up

mis-using ‘‘Water Use Efficiency’’ – conventionally a productivity indicator – to arrive at something called ‘‘Water

Use Efficiency at basin scale, or basin efficiency’’.

At least we know what classical efficiency is, even if it ‘‘gives flawed recommendations’’ (to quote Naim again).

This further highlights a key objective of the paper, which is to make the case that water-related terms involving the

word ‘‘efficiency’’ are often misleading. Basin efficiency is perhaps an extreme example of this.

In the course of drafting this response, I have heard from David Seckler that he now favours ‘‘Effective Basin

Efficiency’’, which leads neatly to . . .Effective Efficiency:

I tried to make clear in the paper that this concept has contributed to thinking and demonstrated that it is possible

– in certain narrowly specified circumstances – to combine quantitative and qualitative measures of water use. But

(contrary to Naim’s assertion that ‘‘any hint for multidisciplinary application has little bearing on the purpose of this

paper’’) it was precisely the objective in the paper to produce a set of terms that can be applied to all sectors: to

quote again from the original:

‘‘The first priority is to define terms that can be used unambiguously by planners, hydrologists, engineers and

others, such as lawyers and economists, concerned with analysing water resources. Given that the science of

hydrology has been in place for many years, it provides the most tested framework, and whatever the irrigation

profession finally opts for should be entirely consistent with hydrological analysis.’’

Effective Efficiency fails this test entirely.

Originally, Effective Efficiency was applied to Egypt (as I recall), with a specified ‘‘parts per million’’ salt

content as the datum definition of what constitutes usable ‘‘water’’. In subsequent years, the issue of the multiplicity

of possible pollutants/uses/crop types was raised, and more recently, I understand that this point has essentially

been recognised and EE is now measured with reference to a standard crop. This entirely recognizes the datum

issue, and the problem increases exponentially when non-agricultural uses are included. Hence my conclusion,

advocated or supported by all commentators on the paper except Andy Keller and now Naim, that we need to

separate quality and quantity issues. Naim’s proposal seems to be that an ‘‘index such as chemical status in WFD’’

or similar should be used. But we then have to weight the various categories of pollutant so end up with a highly

complex system where downstream use inevitably dominates the weightings.

This type of pollution-centred analysis has to be done, but conflating it with the quantity issue simply obscures

both. How will you size your outflow channels if all you have is a pollutant-adjusted water-equivalent flow to work

with? Probably you would also like to know the actual volume of water too.

Copyright # 2008 John Wiley & Sons, Ltd. Irrig. and Drain. 57: 249–252 (2008)

DOI: 10.1002/ird

250 C. PERRY

Naim then suggests a ‘‘quantity only version of EE’’ that includes return flow. So we abandon the attempt to

conflate quality and quantity, a step forward, but continue with the ‘‘E’’ word – which the quote above demonstrates

rather clearly is a source of confusion in and of itself.

I have recently visited Yemen and Tunisia. Both countries face at least local water scarcity – and problems with

pollution. They are both in the process of making irrigation ‘‘more efficient’’ to resolve these problems. How much

better if they had been focussing on (a) reducing non-beneficial consumption and the non-recoverable fraction, and

(b) increasing the productivity of the consumed fraction. I think that identifying those components of the

hydrological cycle would have helped.

For a final comment on Effective Efficiency, see last comment related to Naim’s section 3, below.

I now go through the paper with more general comments:

1. Obviously, if re-specify objectives, the paper may not meet them. I am not sure Naim’s re-specification is

correct: the point of the paper was (a) to demonstrate that on the one hand there is an established methodology

for analyzing water flow in a river system, and that the use of the various ‘‘efficiency’’ terms confuses that

analysis and leads to false conclusions, and (b) to recommend an alternative based on years of work and

publication by other respected writers and practitioners (and finally to point out that other practitioners are

going the same way).

2. I think the paper does follow these lines, and not surprisingly, does not meet the objectives preferred by Naim.

Yes, there is an array of terms that include a reference to ‘‘efficiency’’, but that is exactly the point – the

multiplicity (a) leads to confusion, and (b) always implies that ‘‘better is higher’’. (reference the ‘‘Water

Framework Directive’’ which requires us all to do things that sound nice like ‘‘promote an efficient and

sustainable water use’’. Naim later criticises my reference to an individual’s comment on this topic. He is a

senior official in the UK responsible for implementing whatever that phrase might mean; I think his personal

views are quite relevant – it is certainly easier to write such phrases than to interpret and implement them.

That same source recently told me that he and his department head were recently asked by a parliamentary

committee to define ‘‘water conservation’’ and ‘‘water use efficiency’’. They separately produced very

similar definitions, but applied them to the opposite terms. . .)3. A) as indicated in the text, it was not the purpose of the paper to ‘‘shame’’ countries or agencies, and I still

prefer anonymity.

B) The Gleick example was seminal. How many people, told that an investment that induced a reduction in

‘‘real demand’’ for water would NOT expect saved water to be available for other uses? Again, we end up

playing with words and each taking his own meaning from it. Every politician in the world would be busy

funding expansion of every water-using activity in his constituency once he knew that the current ‘‘real

demand’’ for water had been halved. . . Naim may be aware that the actual units are ‘‘diversion require-

ments’’, but he is an expert and would read the associated material. In the ICID’s proposed new terminology,

there water use would be reduced (‘‘Use’’ being the application of water to any specified purpose, without

clarifying whether the use is consumptive or not), but no reduction in consumptive use would be achieved,

and hence no freeing of water for additional consumptive use elsewhere.

I am glad I was forced to think again about these issues: I began feeling confident that the weight of

evidence supported the conclusion that EE is of limited value and prone to encourage confusion and

misunderstanding. I remain convinced after further thought.

4. A) Obviously one can opt to combine the various fractions in ways that are useful, or not. (As Francois Molle

has pointed out, in the end it is politics that makes these tradeoffs, not multi-dimensional matrices that hide

our inevitably subjective weightings. (I’ve read Naim’s paper on how this process should all be documented,

but do not believe that it is a substitute for the actual process, which should be the clearest, most definitive

‘‘facts’’ we can present, as an input into the inevitable political process.)

The main point is that the meaning of each fraction is clear. This is not the same as saying that it is easy to

specify beneficial use where there are parks, small wetlands with wildlife, etc. But at least we clarify what we

are trying to define. Measuring efficiency (effective, classical or basin) rarely does that.

C) The trouble with the point here is that you must again define what constitutes ‘‘pollution’’.

Copyright # 2008 John Wiley & Sons, Ltd. Irrig. and Drain. 57: 249–252 (2008)

DOI: 10.1002/ird

REPLY 251

In sum I would argue that greater clarity will be achieved for policy makers, planners (in all sectors), the general

public and politicians by moving to the proposed new set of terms. Basin efficiency is already dead, so we can

ignore that one; Effective Efficiency perhaps has a small band of adherents, but the weight of opinion is elsewhere.

We do NOT need more confusion, and just as I would promptly have complied with any swell of opinion towards

(say) using ‘‘depletion’’ (IWMI) rather than consumption, or reuse water (California DWR) rather than recoverable

fraction, I recommend the EE group to consider the benefits of joining the mainstream.

Finally, let me point to another group that is already in the mainstream. Dr Stephen Foster is President of the

International Association of Hydrogeologists. He was recently quoted as follows (http://findarticles.com/p/articles/

mi_qn4158/is_20040128/ai_n9689879):

‘‘[T]he idea that making irrigation more efficient will free water for other uses. . . has the makings of a very

dangerous myth. There is a horrible flaw in the argument. Most of the water being ‘‘saved’’ is never truly

wasted in the first place. Some, it is true, is lost to evaporation. But most – the water that seeps underground

from fields and canals – eventually finds its way to nature’s underground water reservoirs, from which millions

of farmers subsequently pump water to supplement river water for irrigation.’’

Nicely stated.

Copyright # 2008 John Wiley & Sons, Ltd. Irrig. and Drain. 57: 249–252 (2008)

DOI: 10.1002/ird

252 C. PERRY