Examination of Witnesses (Questions 160
- 169)
WEDNESDAY 7 NOVEMBER 2007
PROFESSOR EDMUND
PENNING-ROWSELL
AND PROFESSOR
HOWARD WHEATER
Q160 Mr Drew:
If we can look at this issue of the maintenance of existing flood
defences, if you look at some of the evidence that has come our
way—which I presume we have published and so is in the public
domain—there are a lot of people who feel very strongly
about some of the maintenance gaps. We have had this popular debate,
for example, should we be dredging the rivers? I am pretty sure
that this is not helpful in terms of anything other than good
maintenance, but it would not to my mind prevent flooding. I just
wondered where both of you stand on this issue about the degree
to which the Environment Agency, and indeed the water companies,
have been negligent in some of the maintenance programmes that
they have operated, and is this something that in a sense we should
be really hot on in terms of our report?
Professor Wheater: I do not really
have personal expertise to give you a comment on that. I think
there are people who could help you, so there is Professor Jim
Hall from Newcastle who has done a lot of work in this area, and
a team at Hydraulics Research at Wallingford, including Dr Paul
Sayers, but I have just not been involved with the maintenance
side of the business.
Professor Penning-Rowsell: The
same.
Chairman: It is no use asking
these two!
Q161 Mr Drew:
Could I have a quick rejoinder there. You have given us some pointers
as to who we should go to, but looking at the more strategic direction,
you said that you are not expert but, again, if I was a climate
change denier, which I am not, I think I could come up with a
pretty good set of opinions on how this could all be sorted out
in due course of time, we do not need all this big map stuff,
we can deal with it on a pretty micro level, and just a few thousand
years will make all the difference. I see Professor Penning-Rowsell
has been roused!
Professor Penning-Rowsell: I think
you have to remember that in the 2007 events very few flood defences
failed. They may have been overtopped—
Q162 Mr Drew:
--- Hilary Benn always reminded us on that.
Professor Penning-Rowsell: I think
that is a very important consideration and poor maintenance, if
it were really poor, would show itself as failure; it would not
show itself as over-topping because every flood defence has a
finite standard and may be over-topped, particularly when you
get ten centimetres of rain in 24 hours. If you are to criticise
maintenance you would have to show that there were widespread
failures and I do not think you can demonstrate that.
Q163 Chairman:
Do I assume that perhaps the probing of you gentlemen about changes
in farming practice and flooding may also be slightly outwith
your knowledge?
Professor Penning-Rowsell: No,
he knows lots about that!
Chairman: Roger, you are on!
Q164 Mr Williams:
In terms of land management there are two ways you could approach
it: change your land management to prevent run-off; or dedicate
land for taking water that could flood other areas. Are both those
approaches being investigated?
Professor Wheater: Yes, I think
there are some important issues in the area of agricultural land
management and river flood plain management, and technically they
are quite challenging. I think it is clear that there has been
a very large amount of intensification in the rural agricultural
sector and there is quite a lot of anecdotal evidence that that
has given rise to increases in local flooding, but there is no
evidence of what the impacts might be at the larger scale of the
Severn River, for example. At the moment I lead a research programme
which is working with a consortium of farmers in Wales to consider
impacts of intensification on the way in which run-off is produced
and what that might do for flood risk. Just to give you some examples,
over the period from the 1970s to the 1990s the number of grazing
animals—sheep mostly—went up by a factor of six and
in some cases the weight doubled, and so the farmers themselves
were very concerned about issues of compaction and the fact that
they perceived that run-off was occurring more rapidly and streams
were having more flashy response and a higher flood response.
Interestingly what the farmers have been doing is to reinstate
some of the features they were paid to take out—and that
is things like hedges and shelter belts—and what has been
observed as a result of that is a significant improvement in the
structure of the soil and hence its ability to absorb water. We
are carrying out trials at the moment with different land use,
different grazing densities, different land use in terms of tree
planting, and those are fairly long term, and we have also developed
models which have been built around the data to come up with predictions
of effects, and you can clearly see that if you put tree shelter
belts, improve the soil structure and put them in the right places,
you can improve flood risk. The level of improvement is still
very much open to debate, particularly as you move up scale, and
of course the effects are likely to be much more evident for the
frequent events than for the really big events because with the
really big event everything that is going to run off is going
to run off, and what you do on the land has less effect, but our
work indicates that you might reduce flood risk by the order of
a few tens of per cent. There is a certain amount of work that
has been done at the larger catchment scale, up to 100 square
km, simply by simulation modelling and the conclusions there are
that under an extreme range of different land uses you might see
a ten or 20 per cent change in flood risk. For the rarer flood
events—50 or 100 years events—it might be a three
to ten per cent effect. That is in terms of run-off production.
I think there is certainly scope for mitigating flood risk by
appropriate changes to agricultural practice, and those are the
sorts of changes that are consistent with what you would need
to help the problem of nutrients and pollution from fertilisers
and so on. Thus there is a need for an integration of land management
and water management; I think that is clear. The problem of transmission
is very interesting because clearly the history has been that
flood plains have been progressively disconnected from the rivers
for urban protection, and also to increase agricultural productivity,
and there is a lot of interest in reconnecting them and using
them for retarding the floods and stalling the floods. There are
some examples of flood mitigation schemes which use constructed
flood plain storage, but there is a lot of interest, I think,
within the agricultural sector in the return of some farmland
to increasingly active use for flood mitigation, and that can
have quite a significant and beneficial effect.
Q165 Chairman:
I just want to conclude to go back Professor Penning-Rowsell to
some critique you were making about the scoring system for prioritising
future flood expenditure. The Chartered Institution of Water and
Environmental Management have advised the Committee that this
activity should be reviewed because they say that the rules of
the system "allow for almost no consideration of scheme components
that do not directly contribute to flood alleviation", and
they would like to see what they describe as a more holistic approach
to be adopted in terms of the scheme justification criteria.[5]
Taking that into account, are we too narrow and too restrictive
and, in contrast, are there any other types of flood prevention
prioritisation processes that you have seen outwith of the United
Kingdom that we ought to be aware of and ought to look at?
Professor Penning-Rowsell: The
answer is we have been too narrow but there is a change being
made now away from a narrow economic appraisal of flood and coastal
erosion risk management investment towards a series of outcome
measures which are broader in scope, and Defra has been consulting
and the Agency has been consulting over the last, I guess, 12
months on that new system, which would move away from a simple
economic analysis to one based on a number of metrics including
social, environmental and economic considerations. In that respect,
I think we probably are ahead of practice in many countries which
are only just catching up with our rather narrow approach that
we are now rejecting, if you see what I mean. So if you look at
countries across Europe the investment criteria has become rather
narrow in its focus on economic analysis whereas we are moving
in the other direction. The effects of that other direction in
the UK will not be felt for some time because of course the investment
programme that the Environment Agency has stretches ahead for
many, many years—several years anyway—so you will
not see a change immediately, but the philosophy has been changing
quite radically since Making Space for Water was introduced and
Making Space for Water made it clear that a broadening of the
appraisal criteria was needed and it set out some ideas which
have now been taken forward by Defra.
Q166 Chairman:
So effectively this broadening process will not have any impact
until after the current Comprehensive Spending Review?
Professor Penning-Rowsell: I do
not know what the timescale of the Comprehensive Spending Review
is.
Q167 Chairman:
Three years.
Professor Penning-Rowsell: Three
years from now?
Q168 Chairman:
Yes.
Professor Penning-Rowsell: I would
say that the effect of the outcome measures will probably be felt
towards the back end of that period but not before because otherwise
you simply waste the effort that has been put into appraising
the projects that already are in the queue and, as I said before,
the queue is congested and therefore there are undoubtedly schemes
that should be done. Whether a slightly different and broader
appraisal system would bring other schemes in and throw some out,
I am not very clear about, but a change is afoot, and I think
a change for the good.
Chairman: That is a good note
on which to end.
Lynne Jones: Could I ask one last
question?
Chairman: As long as it is a tiny
postscript.
Q169 Lynne Jones:
We were discussing earlier the inadequacy of investment in this
area. Is there any scope for UK plc, as it were, to benefit in
this area—you said we were ahead of game—in terms
of benefits to the economy for having this expertise and offering
it in other countries?
Professor Wheater: I think that
we have a very strong engineering sector in the UK with a huge
international portfolio and these techniques and the skills will
be marketable and used worldwide, particularly I think within
Europe under the new Floods Directive that will encourage much
more of an integrated assessment, and I think there are opportunities
there.
Chairman: Jolly good. Thank you both
very much indeed both for your oral evidence and, as I said at
the outset, for your written evidence. There may be one or two
points upon which we would like to quiz you further and I hope
you will not mind if we decide in the future to write to you.
Thank you very much indeed for giving us the benefit of your knowledge
and perspective; it has been genuinely very useful.
5 Ev 481, para 23 Back
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