Dave Ferguson - 6-Mar-2008
- The Environment Agency has completed its
review into the July 2007 summer flooding
in Swindon when up to four inches (96mm)
of rain fell on the town in just 15 hours.
The review concludes that the widespread
flooding in many areas was as a result of
flooding from the rivers, surface water,
groundwater, sewer flooding or a combination
of these.
This torrential downpour
on the 19 and 20 July, combined with an
unusually wet May and June, with rainfall
up to 195% above the long term average,
caused flooding from the River Ray and the
River Cole (which rose by up to two metres
in some places), as well as their many tributaries,
surface water flooding and drainage sewers.
The Environment Agency
has now come up with several recommendations
to take forward with the help of local partners,
and for residents themselves.
Susan Servais, a technical
specialist at the Environment Agency, said:
“The weather we had on the 19 and 20 July
was the catalyst for some of the worst flooding
to hit Swindon for several years.
“While this combination
of factors was obviously exceptional, it
highlighted a number of issues across the
town, particularly from smaller, localised
streams and rivers, and surface water run
off.
“As a result of the
review, which draws upon knowledge from
local residents, the emergency services,
local councils and our flood risk teams,
we have put together some recommendations
for ourselves, local residents and other
groups, which we hope can be used to reduce
the impact and risk of any future flooding
in Swindon. There may be areas such as the
Liden Brook, which still need to be looked
at in more detail in order to ascertain
exactly what flooding occurred and where
it came from.
“Some of the recommendations
we have made include optimising the flow
of watercourses by raising low spots in
banks or enlarging culverts when possible,
encouraging new developments to make improvements
to existing systems and working with the
local authority to reject inappropriate
development.
“However, there are
a number of things residents can do to help
themselves reduce the impact of flooding.
These include signing up for our free Flood
Warnings Direct service where it is available,
considering resilience measures for homes
and ensuring that riparian owners understand
their responsibilities to clear ditches
on their property.
“They can also ensure
that they have a flood action plan in place,
ideally one which has been undertaken within
the whole affected community, to look at
ways of dealing with flooding should the
worst happen again.”
The recommendations will now be discussed
with other partners who may be able to carry
out works which will help to reduce the
risk of flooding in Swindon.
To request a pdf version
(7 Mb) of the report, please email thwest@environment-agency.gov.uk
(please quote: Swindon Floods Review: July
2007) or hard copies are available by calling
01491 828511 between 9am and 5pm.
Notes
July 2007 Flood Facts
The two main rivers
flowing through Swindon are the River Ray
and the River Cole, both of which are tributaries
of the Thames. There is a network of smaller
streams and ditches that flow into these
two rivers throughout the area.
The drainage systems and rivers were inundated
by intense rainfall on the 19 and 20 July.
Rainfall recorded at
the Covingham rain gauge was 96mm in 15
hours, and in Swindon at the Rodbourne Sewage
Treatment Works 80.2mm in 15 hours.
This caused widespread
flooding in many areas as a result of fluvial
(i.e. from rivers), pluvial (i.e. surface
water), groundwater or sewer flooding or
a combination of these.
The return period for
the flooding was found to be between 50
and 100 years, well in excess of the carrying
capacity of most of the watercourses within
the Swindon area. The only exception was
Haydon Wick which had a return period of
30 years.
Where low points were
indicated in flooded areas, bank surveys
are recommended so that it will be possible
to pinpoint locations which would benefit
from flood bunding. Although we know that
such bunds would not be helpful for the
high return period events (i.e. July 2007)
it should provide residents with protection
during lower order flooding.
We have an ongoing maintenance
programme for the Swindon area. For example,
significant clearance work recently took
place on the Whitehill Stream in Westlea
as part of this programme.
Trigger levels and level
recording instruments will be checked and
improved where possible to improve accuracy
of flood warnings.
We will continue to
encourage and support communities in producing
flood plans.
