REPORT
: FLOODING IN BRIDGE 2001 - property insurance
In early Spring 2001, the River Nailbourne flooded
through the valley from Elham to beyond Wickhambreaux where it
joins the Little Stour. The rainfall during the autumn and winter
of 200/2001 was the heaviest by far since records began in 1766
and for the South Canterbury area the annual rainfall was well
over double the average. Nobody can recall flooding from the Nailbourn
to anything like the extent of 200/2001.
Properties in the village of Bridge were affected
and the Bridge Parish Council joined with all the other parishes
along the Nailbourne to form a committee - Little Stour and Nailbourne
River Management Group (LSNRMG) to investigate the cause and to
bring pressure to bear on the various statutory authorities to
ensure corrective action was taken to avoid a re-occurrence. The
author of this brief report was a Parish Councillor on Bridge
Parish Council and undertook to represent the parish on the LSNRMG.
Initially under the supervision of the City Council
and more lately the Environment Agency the whole of the Nailbourne
river channel has been inspected and cleaned out. Dredging and
removal of any shoals of material and removal of vegetation and
debris has also taken place. This has resulted in the capacity
of the river channel increasing over and above what existed when
it flooded. Other improvements have been made to some of the culverts
where there were potential restrictions and Kent Highways has
cleaned out to original capacity all road culverts. Since that
initial major work after the flooding there has been regular inspection
and clearance of the river channel by the Environment Agency.
At the time of the flooding there was a major
restriction to the river at the Mill Lane (Bridge Place) footbridge.
This caused water to back up and flow into Brewery Lane. This
footbridge has been totally renewed by Kent County Council and
the flow capacity of the river has been significantly increased.
A further general improvement has been made to the highway drainage
in the High Street by Kent Highways, which will help to reduce
flooding in the village. Two parallel events occurred which affected
property insurance :-
a) the government agreed a 10 year moratorium with the insurance
companies to not increase rates specifically on properties affected
by flooding.
b) The Environment Agency (EA) prepared maps that allegedly indicated
the flood zone, in our case those associated with the 2001 events.
See Drawing "B ".
The Environment Agency has not been able to put a firm return
period on the Nailbourne flooding basically because there is nothing
at all recorded previously to match it against. The Environment
Agency estimate the return frequency flood to be between 1 in
50 and 1 in 200 years.
Now in 2012 the moratorium is about to be lifted
and all properties within the flood zones indicated on the Environment
Agency maps will face increased insurance premiums. This is linked
to postcodes which alert insurers to check the EA maps. There
have already been reports of new house purchasers being refused
insurance or being asked for high premiums.
The flooding in Bridge in Spring 2001 reached
a maximum depth of 300mm near the ford in Mill Lane and in most
properties affected, reached no more than 150mm dependent on the
ground floor level. Drawing
"A" shows the recorded extent of floods in Bridge.
The author occupies 90-92 High Street, Bridge and was directly
affected. Drawing “A” has not been agreed by all householders
shown.
The LSNRMG has met 2/3 times a year since its
formation in 2001 and in summary has monitored the following :-
(i) Extensive efforts by the Environment Agency (EA) to clear
the Little Stour and parts of the Great Stour of debris, trees
and all impediments to the general flow. Dredging has been undertaken
for the first time in many years.
(ii) The EA has overseen work by the riparian owners to clear
banks etc and maintain a clear channel for the river flows.
(iii) Action by River Stour Internal Drainage Board to similarly
ensure open flows.
(iv) To pressure other agencies who have some responsibilities
with respect to the River Nailbourne and other water systems or
who were caught up in the flooding i.e. Southern Water.
(v) To pressure Southern Water to inspect and repair the main
foul drainage system which also runs down the valley and which
became water bound and a catalyst for water rising through manholes
and causing effluent to become enmeshed with the surface water.
The LSNRMG has been very successful in ensuring
removal of many of the 2001 obstacles to the water flows such
that the risk of a future "back up" and localised flooding
has greatly receded. Southern Water have recently repaired joints
in the main sewer substantially reducing surface and ground water
ingress into the sewers but have not as yet any responsibility
to deal with the ‘laterals’ from this system.
Should there be a similar situation in the future
the Environment Agency has now instigated a full flood warning
system for the Nailbourne, including Bridge. Because of the nature
of the river, which is fed from an aquifer, it will be possible
to give a few days notice of probable high flow in the river which
will allow residents etc time to take their own precautions against
possible flooding – floodboards, sandbags etc.
The conclusions that can be drawn from this ten
year exercise is that :-
a) there is a much reduced risk of a future pluvial
flood given the same rainfalls
b) the local agencies have a greater knowledge of the possible
consequences
c) the local residence have a greater knowledge of cause and effect
d) the planning authority are more vigorous, when granting approval,
in asking for scheme that reduce the surface water run off.
Attached to this report are :-
Drawing “A”
– contemporary report on actual flooding in Bridge Village.
(2001)
Drawing “B”
– EA current "Risk of flooding map" (from website
03/2012)
Drawing “C”
– an overlay of the risk of flood map onto a detail O.S.
map of the centre of Bridge.
Conclusions :
It is clear that the EA map encompasses numerous
properties that due to their ground floor datum level were not
affected by the 2001 flood, had no claim against any insurance
company and are no more at risk now than in 2001. Given the extensive
work by LSNRMG with all agencies, the ability of the River Nailbourne,
the Little Stour and to some extent the Great Stour to cater more
successfully with any increase water flows is assured and will
be monitored in the future.
Thanks to:- Ted Edwards Senior Drainage Engineer.
Canterbury City Council and Jill Thomas, Secretary LSNRMG
Mervyn Gulvin RIBA - March 2012
|
