APPENDIX 38
Memorandum submitted
by Mr Malcolm Read (F63)
Although members of the Select Committee will
be familiar with my writing to them on agricultural policy, your
press notice of 23 June reminds me that I should make a contribution
on the question of flood defence. The insight gained as the main
hydrological witness for the objectors to the (now cancelled)
A36 Salisbury Bypass is I feel worth passing to the committee's
inquiry.
I found myself in this position having taken
a keen interest in Salisbury's two major floodplains—as
a member of the LPA during the eighties. The Avon and Nadder join
in the shadow of the Cathedral. There are also three other rivers
which join the Avon within a two mile radius of the spire.
In December 1988 Tesco dumped the surplus soil,
from the site of their new out-of-town superstore—onto four
acres of the nearby Avon floodplain. The rivers' authority (which
was in its one year change-over from Wessex Water to the NRA)
wrote to the contractors indicating a daily fine until the soil
was removed. As nothing happened I wrote to the rivers' authority
to enquire what the position was. I was told that no action would
be taken as the contractors had "compensated" for this
loss of four acres of floodplain. Eventually I was given a plan
showing that a length of the river bank of the nearby Avon main
channel had been dug away, and this "compensated" for
the loss of floodplain storage. No calculations were provided
however. I naturally became very suspicious of the concept of
"compensating" for the gradual erosion of the floodplains.
My suspicion grew to alarm when the Department
of Transport announced its plans to construct a massive dual-carriageway
road embankment right across both of these two major floodplains.
(I later calculated that the volume of water passing through Salisbury
in a 100 year flood would be 17 times the flow of water at the
height of the Chichester flood of January 1994). My alarm changed
almost to desperation when the NRA indicated they would not be
opposing the DoTs scheme. As no-one else was willing, I agreed
to take the lead on hydrology at the public inquiry, and registered
as an individual objector to give myself the maximum flexibility
in tackling what appeared at the time to be a very arcane subject.
I felt that I had done the right thing when
the DoT's expert witness said that hydrology was "a philosophical
technical question". In other words it is an inexact "science"
where the practitioners make great claims to prescience, but are
always surprised when a flood occurs, saying that these particular
events could not possibly have been foreseen.
If I sound scathing about the "science"
of hydrology, it is because I see it as very much a "part
of the problem" of diminishing floodplains. For example the
DoT produced both an hydrological study, and a vast hydraulic
study, which purported to show that these road embankments across
both floodplains would not increase the flood risk to the city
of Salisbury.
It was easier to challenge the hydrological
study at the inquiry. By briefing other objectors to ask certain
points before my own appearance (three days and two half-days),
I was, (according to others), able to demolish the DoT's proposals
for "compensating" for the loss of floodplain storage
on the land to be taken out for the road embankments. The proposal
was to dig out large "lagoons" on the floodplain itself
which were supposed to provide alternative flood water storage.
However, as I pointed out, in a permeable catchment
(as the Avon system mostly is), flooding does not occur until
the catchment has soaked up a lot of water to become saturated.
By which time the holes on the floodplain will have filled to
ground level, by a combination of rain water, ground water, or
even an earlier, partial flooding in the floodplain, which cannot
drain back into the channel as the above ground-level floodplain
storage does. Once a permeable catchment has become saturated
and starts to discharge the river remains at the top of its bank
for a couple of months. This would prevent a so-called storage
lagoon from draining away once it is filled, and so when the real
flood occurs it does not provide any additional flood water storage
to compensate for the loss of the original above ground-level
floodplain storage.
Under my questioning the DoT's witness agreed
that their "compensation" scheme was therefore "cosmetic".
However he added that this really didn't matter as it was a very
large floodplain, but they had to present such a scheme to satisfy
the NRA. Unfortunately the NRA was not present to answer why they
had accepted the veracity of a scheme which the DoT later agreed
was "cosmetic". The DoT's evidence stated that the NRA
had "expressed their satisfation" with their scheme.
Despite this the Inspector refused to ask the
NRA to attend, even though I pointed out that the rules stated
that if "another government department" supports a scheme,
they should appear. The NRA had entered written evidence, they
were of a similar status to a government department, and the rules
were drawn up before the advent of quangos.
The Inspector seemed to be fully a part of this
charade; in addition to refusing to ask the NRA to attend the
inquiry, he concluded in his report—"The wetlands (lagoons)
are therefore of minor consequence, but are required by the NRA."
So the scheme which was supposed to compensate
for a substantial loss of floodplain was ageed by the DoT to be
"cosmetic", and was described by the Inspector as "of
minor consequence". The NRA were not asked what they thought
about being duped because they did not attend the inquiry.
The question however which remains unanswered
is—was the NRA duped? Or were they willing parties to a
deliberate attempt to deceive the public on the question of "compensating"
for the loss of floodplain storage?
For his part the Inspector took no notice of
my argument that any other developer could come along and demand
to build on the floodplain, on the grounds that he was going to
provide "compensating" flood storage, albeit of a similarly
"cosmetic" nature. Is it any wonder that floodplains
have been eroded?
I mentioned earlier that it was easier to challenge
the hydrological part of the DoT's evidence than the hydraulic.
This was because the latter was based upon computer modelling.
However an opportunity did present itself because a couple of
months after the Bypass Inquiry closed, the Salisbury District
Local Plan Inquiry opened. Among other things, this inquiry had
to look at the District Council's proposal to locate a large area
of housing and also light industrial use, on the side of the Nadder
floodplain. (The NRA was present at this inquiry, but they were
appearing as THE COUNCIL'S EXPERT WITNESS—in support of
the proposal to build on the floodplain.)
The argument used by the Council (and the NRA)
was that the site in question was not actually on the floodplain.
In support they produced an hydraulic computer model which showed
the 100 year flood level not covening the area in question. (It
should be noted that hydrologists recognise a floodplain to be
that area indicated by a computer model to be flooded in a 100
year flood, rather than the flat area on either side of the river
which has historically flooded.)
Fortunately, on looking through the evidence,
I noticed that this hydraulic model had given a 100 year flood
level which was nearly a metre lower than the DoT's hydraulic
model had given for the same location. I pointed this out to the
LP Inquiry Inspector and his attitude towards hydrological expertise
changed dramatically. He ordered a third firm of consultants to
look into the discrepancy between the two models. In its report
they mentioned the "residual unexplained difference"
between the two predicted flood levels.
The NRA continued to support the Council, but
the Inspector recommended deletion of the site from the Local
Plan on the grounds than computer modelling was not sufficiently
reliable, and he would sooner rely upon the precautionary principle,
and also the historical evidence of where the floodplain boundary
might be. The Council accepted his recommendation.
So the hydraulic model which was used by the
DoT showed a high 100 year flood level, to support their claim
that the bypass embankment would not increase flood levels in
a 100 year flood, and the model used by the Council showed a low
100 year flood level to support their claim that their proposed
development was not even on the floodplain at all. The dear old
NRA "expressed their satisfaction" with one of the models,
and actually turned up to support the veracity of the other model.
I put all of this to the Secretaries of State
who were reaching a decision on the Salisbury Bypass. In their
"minded to approve" letter of 22 October 1996 they "noted
that the L P Inspector had taken a cautious approach in the light
of differing predicted flood levels in the Nadder". But they
also noted that the development "has not been rejected purely
on hydrological grounds". (So in the twisted logic of officialdom,
if something has been rejected on two grounds rather than one,
it is possible to invalidate both objections purely on the grounds
that each was not the only objection).
So despite the fact that the bypass was eventually
cancelled, as far as Whitehall was concerned hydrology was not
a factor. Whitehall was clearly not ready to accept any evidence
that pointed to the fact that the only way to maintain flood storage
is not to build on floodplains.
The Chichester flood took place during the course
of the Salisbury Bypass Inquiry, and as the flood waters were
starting to recede, I drove to Petersfield and thence down from
the head of the Lavant valley. Whilst the Lavant runs in an underground
culvert under the City of Chichester, this requires a floodplain
just as much as one which runs in an open channel.
Obviously the floodplain cannot follow the route
of the underground culvert, and so the excess flood water should
have been allowed to have flowed towards the sea on the east side
of the city. Sadly this route was blocked by all sorts of development,
but it was nevertheless the "detached" Lavant floodplain,
and should not have been built on. The ensuring memory of my visit
was of seeing the recently burnt out Sainsbury superstore standing
in a vast expanse of flood water.
The Salisbury Bypass Inquiry Inspector would
not allow me to introduce general conclusions from my visit to
Chichester. He would not call the NRA to the inquiry, and he allowed
the DoT to answer the 20 or so questions I had drawn up for the
NRA to answer. Clearly the Inspector and the NRA were instructed
that the bypass inquiry was to be no more than a formality.
Had a change of Government not caused the bypass
to have been cancelled, the Council would have come back again
with its proposal to build on the floodplain. (I forgot to mention
that this was between the line of the proposed bypass and the
existing edge of town). The City of Salisbury would by now be
well on its way to losing the valuable protection afforded by
its two major floodplains.
As for the DoTs point (supported by the inspector),
that these floodplains are pretty large and can afford to lose
some ground; a recent and belated study of the floodplains by
the Environment Agency says that certain parts of the city are
already below the 100 year flood level of protection, which is
the standard set by MAFF. So much for our large floodplains.
My conclusion from this four years of work (which
cost me a great deal of money in phone calls and postage—without
a penny in expenses), is that the official policy, that it is
possible to "compensate" for building on floodplains,
is a sham.
My second point is that hydrology and hydraulic
modelling has been used to obfuscate, to deceive the public and
to lull everyone into a false sense of security with regard to
building on the floodplain. Real fears about flooding and common
sense, based on historical events, were dismissed as "anecdotal
evidence", whereas something coming out of a computer was
regarded as real evidence.
Thirdly the NRAs lower order of officers were
bemused by this false science. They were not "hydrologists"
and so did not question the "expert witnesses" employed
by those who sought to build on floodplains (liars for hire?).
I suspect that the higher order of NRA officers were capable of
being leant upon by civil servants in the DoT.
As for the future; I cannot see the Environment
Agency doing any better unless its becomes official policy to
prevent all further development on river floodplains, with no
exceptions granted on the grounds that loss of flood storage can
be "compensated" for.
My best wishes to all members of the committee.
25 June 1998
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