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Flood prevention measures at Comrie
James Irvine
Teviot Scientific, Cultybraggan Farm, Comrie,
Perthshire
Filed 20 Dec 06
©www.land-care.org.uk
Three rivers merge at Comrie: the Earn, the Ruchill
and the Lednoch. Indeed, the now large Perthshire village of Comrie
takes its name from the Gaelic ‘Conruith' - meaning the confluence
of streams.
It is therefore hardly surprising that Comrie
has experienced severe flooding, from time to time, going back in
history. The water catchment area for each of these rivers is vast
- Glen Artney, Glen Lednock and of course Strathearn - with the
River Earn flowing from Loch Earn, which extends some 10.5km from
St Fillans to Lochearnhead. After a prolonged period of rainfall
the ground becomes so saturated that further rainfall causes the
rivers to rise rapidly - by many feet in a matter of just a few
hours in the case of the Ruchill. Water can be held back in Loch
Earn by a gating system, but for only so long. Otherwise the level
of the loch would rise to such an extent that the roads and dwellings
close to its shores would be seriously threatened. The River Earn
flows through Strathearn to join the River Tay Estuary 75km
away.
The rapidly rising River Ruchill
on Wednesday 14th December.
Within a further hour the whole field was flooded.
A quite river had become a vicious torrent.
(To enlarge photo Click
Here)
Photo ©Kimpton Graphics
And so it was on Wednesday 13th December 2006
- in much the same way as in earlier years, notably in February
1997 and in 1993, when a number of streets and houses in Comrie
were flooded, as well as farm land and farm buildings. In 1997 the
peak flow in the River Ruchill reached 250 cubic metres per second.
Part of the damage done by the recent flood was
substantial erosion of the bank of the River Ruchill - a matter
of considerable environmental importance as emphasised by Scottish
Natural Heritage, as well as being a loss to the farm.
Major
erosion of the banking of the River Ruchill
at Cultybraggan Farm, Comrie caused by the recent flooding
(To enlarge photo Click
Here)
Photo ©Kimpton Graphics
Following the 1997 event, a flood prevention plan
was drawn up and put into effect in relation to the River Ruchill.
But it came in for serious criticism on account of the extensive
environmental damage it incurred and its poor design (1).
Any competent flood prevention plan is also dependent upon good
maintenance of the facilities that it provides and of existing facilities,
such a drains and ditches (2).
A number of other highly expensive surveys were
subsequently commissioned, including one that advocated the placing
of J-Vanes in the River Ruchill, with the aim of redirecting the
flow of the river so as to avoid erosion of its banks.
However, this was dependent upon fallen trees
that had been washed downstream being removed from the river promptly
- a condition that Perth & Kinross Council clearly could not
fulfill.
Rock armour placed further down the
River Ruchill
to protect the river bank, although it might have been made more
sightly.
This picture was taken just four days after the flood, indicating
how
dramatically the river level can change in a short period.
(To enlarge photo Click
Here)
Photo ©Kimpton Graphics
Rock armour was placed just upstream from the
Dalginross Bridge at Comrie but, sadly, did not extend further up
river. Cultybraggan Farm had no objection to the placing of such
rock armour to secure the banking, as it should be put in place
using appropriate machinery operating from the river bed when the
river is low. This past summer has been a particularly dry one,
when drought was a problem. The River Ruchill was low for many months,
but nothing was done - other than the removal of fallen trees from
the river bed, using machinery operating in the river bed with the
agreement of all concerned.
It is to be hoped, however, that a more attractive
way of using rock armour could be devised to preserve the scenic
beauty of the area and its important wildlife habitat. Trees and
other forms of vegetation should be planted along the river bank
- rather than being removed - in order to help bind the soil and
thereby diminish erosion. The path along the river bank is a right
of way, so it would be to the advantage of the walkers to do a tidier
job of protecting the river bank.I would submit that the funding
of such projects would make better use of resources than the sort
of land management contracts that are being promoted at the present
time.
A much tidier method of protecting
the river bank was used
a little downstream, below the White Church at Comrie
This picture was taken seven days after the flooding.
(To enlarge photo Click
Here to View)
Photo
©Kimpton Graphics
Also, after the previous severe flood in
1997, planning legislation was tightened. Authorities were not supposed
to give planning permission for houses to be built on ground considered
to part of a flood plane. Yet, after going to appeal subsequent
to many objections, new houses were recently built on land known
as the Field of Refuge - very close to the River Earn and not many
feet above it, and on what was recognised to be a flood plane.
On Wednesday 13th December
2006, the River Earn came close to flooding these new houses, which
were saved only by the fact that the level of the ground on which
they had been built had been raised a fraction. A more severe flood
would have flooded them. And a more severe flood is clearly possible,
irrespective of the predictions just a few years ago by the authorities
that the risk might be only once in 100 years. How they arrived
at that is a mystery to most people. How planning permission was
granted after such logical objection is also curious.
For all their shortcomings, it would appear that
the changes made to the River Ruchill had altered the pattern of
the river's behaviour. The main flooding at Comrie this time was
not caused by the River Ruchill, but a little further down stream
by the River Earn. Hopefully, future flood prevention operations
can be carried out with much less environmental damage.
Although Comrie had an anxious time - indeed very
serious for some of its inhabitants - other parts of Scotland were
much worse affected. At Milnathort the River Queich burst its banks
and caused serious flooding - this after a £500,000 flood-prevention
project had clearly proven to be ineffective. Blairgowrie was another
area that suffered severely. The River Allan flooded houses at Braco
and closed the road. Many other country roads were closed.
We are told that global warming is on its way,
and that we can expect more severe flooding. We will need to get
better prepared for it
©www.land-care.org.uk
References
1. Editorial (2002). Botched
flood prevention scheme. How not to do it.
See ENVIRONMENT Home page, filed 25 Nov 02, www.land-care.org.uk
Click Here
to View
2. Editorial (2002). Flood prevention.
See ENVIRONMENT Home page, filed 2w Nov 02, www.land-care.org.uk
Click
Here to View
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