GEFAG Queries in Respect of
New Floodplain Mapping.

In March Norwich Union announced a new
style of mapping to make what they claimed to
be more accurate risk assessments for flood
insurance.

Using airbourne survey data known as SAR
(Synthetic Aperture Radar) this gives ground
levels in significant detail in comparison to the
traditional Ordnance Survey mapping.
However it has to be treated with extreme
caution since it is associated with a significant
degree of vertical tolerance. This tolerance can
vary from +/-0.5m to +/-2m.


GEFAG contacted the Environment Agency,
Association of British Insurers and Norwich
Union expressing concern that the press
coverage led to an over-statement of the
accuracy and validity of this new mapping.
The various replies and comments are set out
below. The EA statement is in full: the ABI and
NU are edited.

Norwich Union Flood Map

EA Position and Briefing
INTRODUCTION
On March 3rd Norwich Union launched a newly
developed flood map which they will use as the
basis for flood risk insurance.

This new data is tailored for the needs of
insurers. It will provide greater detail than was
available to Norwich Union in the past.
The map uses a digital model as a base map.
The Environment Agency (EA) is using a
derivative of the same digital terrain model
(DTM) as a base for developing the new Flood
Map, which goes live on the Internet in
September 2004 and is one of many outputs of
the Agency’s 5 year mapping strategy.
ENVIRONMENT AGENCY POSITION
 Norwich Union’s new map is a step
forward: it uses the DTM as a first step
assessment tool in providing people
who live on the floodplain with flood
insurance cover.
 The Norwich Union map is designed
purely for insurance purposes.


The EA is the lead authority on flood risk
information for England and Wales. Our role
is to protect people and the environment from
flooding.
In 2003 the EA embarked on a 5-yr flood
mapping programme which represents a
major step forward and provides the strategic
direction to improve information on flood risk
in England and Wales. The work aims to
meet the many business and external needs
for better flood maps.
We are investing £5 million per year in this
programme which maps flooding from rivers
and the sea and the impact this has on land –
not properties.
The Agency provides flood mapping outputs
based on land contours and not properties.
The reason is that the Agency can not keep an
up-to-date database of property type, form of
construction, size, occupancy and threshold
levels of the 2 million properties on the
floodplain. All these factors will affect the
actual level of flood risk. (The insurance
industry may wish to translate flood data to
determine the effect on specific properties of
interest).
We are constantly gathering and developing
new data and information on flood risk and
will be using the DTM as a significant part of
the process.
Our needs are to assess areas of risk and
ensure people in those areas are aware of
those risks and know what to do when
warnings are issued and how to protect
themselves.
The EA will be producing Flood Zones in June
2004 showing the extents of flood risk for
planning consultation purposes in accordance
with PPG25. These show bands of flood risk
(without flood defences):
Flood Zone 3
represents a greater than 1 in 100 chance of
flooding in any year. Flood zone 2 represents
a chance of flooding between 1 in 100 and 1 in
1000. Flood zone 1 represents a lower than 1
in 1000 chance of flooding in any year.
The most significant outcome of the flood
mapping strategy for the public will be the
new Flood Map which will be available on the
EA website in September 2004. It shows the
Flood Zones and also the location of defences
and will give an indication of likelihood of
flooding in a particular location taking these
defences into consideration.
People will be able to check if they live in a
flood plain, see locations of defences and
areas which benefit from them. It will also
link to advice on what action hould be taken
to prepare for flooding and which warning
services are available.



The new Flood Map will replace the
existing Indicative Flood Plain Maps on
the Internet. Over time the map will be
developed to improve accuracy and
indicate the impact of climate change
and flood hazards which will be
particularly useful for Emergency
Planning.
The EA’s Flood Map will incorporate
broad national scale modelling (similar
to that used by NU) but will also
include more detailed local modelling.
Our current information can be
accessed by the public through the
Internet or by contacting their local EA
Area Office through Floodline.
(Issued : March 22nd 2004)
Norwich Union Comment
GIS Manager / Jill Boulton
NU is seeking to establish the correct risk rating
for each property. If, from our flood map or EA
data we believe there is a risk of flooding worse
than 1 in 75 this is put as a ‘refer’ address which
requires an underwriter to review the position.
That review would ask a customer for any
relevant information that would help us to
assess the risk including floor levels, recent
defences or any other mitigation measures that
have been taken. Equally we are happy to take
other relevant information into account – for
instance some councils have had their own
flood maps produced and, if they are willing to
share them with the industry, these are
incorporated into the results.
Also - because we have this map in-house – we
can discuss with customers if they believe they
have been wrongly rated as “at risk”.
Many properties that suffered flooding in 1998
and 2000 where not thought to be “at risk” at
that time so past claims have been
demonstrated to be a poor indication of likely
future flood risk.
Comment by
Association of British
Insurers
Sebastian Catovsky / Natural Perils
The Environment Agency Flood Risk Information
continues to be the key resource for insurers to use to
implement the ABI Statement of Principles on
provision of flood cover.
Pricing of premiums, however, continues to be a
matter for individual insurers, and ABI encourages
members to make use of more detailed risk
information of their own and from other sources to
develop appropriate products and set premiums for
their customers.
In this context, Norwich Union fully supports and
flows the Statement of Principles. NU supplements
the Environment Agency flood risk data with their
own information on flood risk developed from SAR,
and uses this information to make informed decisions
about levels and price of flood cover.
(Letter – 16 March 2004)
TRENT FLUVIAL STRATEGY
STUDY
GEFAG has written to the EA Project Manager to
clarify the predicted computer results for the
Gunthorpe Area in this report.
There appear to be two calculations of flood height
in the area of A6097 giving significantly different
results – and also being substantially higher than
expected.
This might be leading to the inclusion of more
properties than might be necessary as shown on
the map overleaf.
Please remember that the map show ground cover
and does not take account of floor height:
nonetheless this map does have major insurance
risk implications.
What any insurance company is trying to do is
charge the premium that the risk reflects each
year so that when an event does occur the
money is there to pay for it.
STOP PRESS
No insurer wants to see anyone flooded and we
continue to campaign for better defences and
no development on floodplains but this in
hands of Government.
GEFAG will be presenting various
items at the
ANNUAL PARISH MEETING
Wednesday 26th May in Village Hall
(E-mail response / 16 Mar 04)