Walker Institute, Reading, December 17th 2014
Understanding
UK flood risk:
now and in the
future
Edmund Penning-Rowsell
Member: Flood Hazard Research Centre http://www.fhrc.mdx.ac.uk
Member: Oxford Water Security Network www.water.ox.ac.uk
Editor: Environmental Hazards (Taylor and Francis) http://mc.manuscriptcentral.com/ehaz
Credit: E. C. Penning-Rowsell (Middlesex University) and J. Fielding (University of Surrey)
Copyright (text) FHRC
Two metrics of the
flood risk that we face:
1. The current annual
average damage from
flooding in England and
Wales
2. The number of
properties at risk of
flooding in England and
Wales
Edmund Penning-Rowsell
Member: Flood Hazard Research Centre http://www.fhrc.mdx.ac.uk
Member: Oxford Water Security Network www.water.ox.ac.uk
Editor: Environmental Hazards (Taylor and Francis) http://mc.manuscriptcentral.com/ehaz
Copyright (text) FHRC
1. Our assessment of risk*: Why is a national
economic** assessment of flood risk important?
• It informs the whole UK
discourse and debate
about floods, risk
management and climate
change
• It therefore affects policy
to a significant extent
• It also affects capital and
revenue budgets for flood
risk management
*
Fluvial and coastal ONLY here
** Not financial losses
Who said annual average flood damage was
approximately £1bn in England and Wales??
Document
Foresight Future
Flooding (Ex. Sum.)
Foresight Future
Flooding (Volume 1)
Flooding in England
(the EA)
£1bn
Quotation
“…even with the present flood defences, we experience an (annual) average of
£1,400 million of damage (£1,040 in England and Wales).”
“Within the NAFRA 2002 study it was estimated that the annual average
economic damage due to flooding is, on average, in the order of £1billion pa”.
“The expected annual damages to residential and non-residential properties in
England at risk of flooding from rivers and the sea is estimated at more than
£1 billion.”
“The annual costs of flood damage in England are estimated to be at least
£1.1 billion”.
GoS
2004
Evans
2004
EA
2009
All based on the same NAO
assessment of risk; these 2011
are
Defra
not independent
2011
verifications
Flood risk
management in
England (NAO)
CCRA, main document “Present day Expected Annual Damage (EAD) to residential and nonresidential
(flooding)
properties from tidal or river flooding is of the order of £1.2 billion in England
and Wales. The EAD is an estimate of the average annual damage to property
and contents. The total damage could be much higher if other assets and
indirect and intangible losses are included.”
The EA’s Long Term
“The average annual cost of damage from flooding in England is estimated at
Investment Strategy
more than £1 billion. These costs are borne by householders, businesses,
central and local government and others including insurance companies”.
CCRA Executive
“Annual damage to UK properties due to flooding from rivers and the sea
Summary
currently totals around £1.3billion (and) is projected to rise to between
£2.1billion and £12 billion by the 2080s.”.
CCRA: Floods and
“On average, annual damage to properties and their contents due to river and
Coastal Erosion,
tidal flooding in the UK currently totals around £1.3billion”
Sector Perspective
EA
2011
Defra
2012b
Defra
2012b
2010
2013
The Middlesex FHRC* Manuals:
From 1977 to 2013
Blue
Manual
1970
1977
Centre
founded
Direct
damages
Red
FLAIR
Manual
1987
1990
Indirect
losses
Yellow
Manual
2005 MultiColoured
Manual
1992
2005 2010
Coastal
added
All Update
topics
Why? To seek sensible decisions on
where and when to invest our hardpressed taxpayers’ money on
reducing the risks of flooding…..
Routledge, November 2013
* Flood Hazard Research Centre, Middlesex
University
@fhrc_mdx
From ‘NAAR’ in 2000/2001 to ‘NAFRA’ 2008 (£ billions)
Conclusion
No. 1:
the model(s) appears unstable and
….. modelling flood
risk to gauge
AAD
unreliable
Coverage
Damages p.a.
(England)
Damages p.a.
(Wales)
Damages p.a.
(total England
and Wales
(£bn)
Properties
affected
(England)
Properties
affected
(Wales)
Properties
affected (total
England and
Wales)
NAAR
2000
NAAR
2001
RASP
2002
NAFRA
2004
NAFRA
2005
NAFRA
NAFRA NAFRA 2008(B)
2006
2008(A)
England
England and
Wales
England
and Wales
England
and Wales
England
and Wales
England
and Wales
England and Wales
1.149
But without any
0.626
significant calibration
0.262
0.801
1.060
Results
not
available
2.332*
1.411
5.136
1.281
2,400
Each one2,137
traceable2,400
back to one
source: These, again, are NOT really
independent
169assessments
225
225
1,797
1,909
1,741
Results
not
2,218++
available
2,306
2,625
2,625
…. all accompanied by myriad changes in method and data, but with the same aim
NAAR = National Assessment of Risk.
NAFRA = National Flood Risk Assessment
From ‘NAAR’ in 2000/2001 to ‘NAFRA’ 2008 (£ billions)
….. modelling flood risk to gauge AAD
Damages p.a.
(England)
Damages p.a.
(Wales)
Damages p.a.
(total England
and Wales
(£bn)
Properties
affected
(England)
Properties
affected
(Wales)
Properties
affected (total
England and
Wales)
NAAR
2001
RASP
2002
NAFRA
2004
NAFRA
2005
NAFRA
NAFRA NAFRA 2008(B)
2006
2008(A)
England
England and
Wales
England
and Wales
England
and Wales
England
and Wales
England
and Wales
0.626
1,797
New flood
0.262spreading model
5
0.801
4
England and Wales
1.149
6
Annual average flood
damage (£billions)
Coverage
NAAR
2000
1.411
5.136
3
2,137
2,400Based2,400
2
169
1
1,909
0
1.060
Results
not
available
c. £1bn
1,741
NAAR
2000
2.332*
Results
not
2,218++
available
NAAR
2001
RASP
2002
NAFRA
2004
NAFRA
2005
2,306
NAFRA
2006
1.281
on the
WAAD
225 method225
2,625
2,625
NAFRA NAFRA
2008(A) 2008(B)
…. all accompanied by myriad changes in method and data, but with the same aim
Doubts about
coastal flood
risk:
Foresight 2004
(The only
mapped RASP
result): what
does geography
tell us?
Doubts about
coastal flood
risk:
Most of Blackpool is well above current extreme sea
levels if defences are breached
24m
23m
£10 millions
annual average
damage??
The
Environment
Agency’s
flood maps
showing
defences
14m
9m
£0.25m to £2.5m
per annum
£2.5m per
annum
Doubts about
coastal flood
risk:
Where else is
current AAD
also deemed to
be ‘high’ or
‘medium’?
Is this a pattern
of actual flood
damage that we
recognise?
? Boston
? Dawlish
Doubts about all flood risk:
The (independent) IBM
analysis (2006)
They concluded that “the
NAFRA model over-states
the exposure of the UK
economy (to flood losses)”
(IBM, 2006, 1).
And that this conclusion
“is supported by the views
of the relevant experts
within Defra and the EA
who, from the outset of
this (IBM) project, noted
that the NAFRA
predictions seemed high”
(IBM, 2006, 2).
Conclusion No. 2: some RASP/NAFRA predictions look badly exaggerated
The flood damage record:
What have been the historical damage values?
Date
Economic
losses at 2010
values
1947
1953
2000
2007
£0.45bn*
£5bn
£0.79bn+
£3.2bn
How can the annual average be c.
£1bn if there have only been two
(maybe three) floods since 1894 with
losses greater than that value ?
* £12m at 1947/8 prices (the £0.45bn may well be too low); + 2000 prices
The flood damage record:
ABI data on flood insurance claims (£ billions)
1.2
1
0.8
0.6
From the ABI Press
Release of Nov. 2010 we
get an inflation adjusted
average for the period
1990-2009 of just
£0.226bn
0.4
0.2
£0.272bn
0
The simple average (£0.226bn) has
been up-rated by 20% to reflect
less than compete insurance
penetration (c. 90%) and an
element for underinsurance
The flood damage record:
Environment Agency data on the number of houses
flooded
60,000
50,000
40,000
30,000
20,000
10,000
0
The houses > total AAD is factored by the proportion of 2007 losses
attributable to the residential sector, adjusted to economic values
At an average of
£30,000 per event,
this gives a grossedup (economic) AAD
of
£0.261 bn
The flood damage potential:
London’s flood risk (£ billions)
£0.70
£0.60
AAD
£0.50
£0.40
£0.30
NAFRA value for
the TE2100 area
+ all the Thames
region: £0.66bn
TE2100
value:
£0.07bn
£0.20
£0.10
£0.00
EA Thames TE2100 non- TE2100 nonTotal
TE2100 area Thames area
region
Thames
Thames
Thames
AAD
outside
areas:
areas:
Region plus
TE2100 area
Southern
Anglian
all the
(50%)
(50%)
TE2100 area
Implied AAD in
the rest of the
Thames region of
£0.59bn: This is
simply not
credible
‘Reversing’ the WAAD analysis: What event losses are
‘needed’ to get to the ‘target’ AAD of £1bn?
18
16
Eight times the huge
2007 losses of £1.84bn
Residential flood losses, 100-year event
Flood event losses (£bn)
14
Residential flood losses, 50-year event
12
10
Residential flood losses, 25 year event
8
6
WAAD =
4
2
0
SOP 25 years
SOP 10 years
c. £0.38bn
SOP 25 years
SOP 10 years
SOP 25 years
c. £0.25bn
National residential AAD 'targets' at the national SOPs above
SOP 10 years
c. £0.10bn
Weighted
Annual
Average
Damages
If residential AAD is £0.38bn (to get a total AAD of £1bn), these are the event losses that are needed for
the 100- and 50-year events, assuming a ‘national’ mean SOP of 1:10 and 1:25 years
Summary results: Not £1bn+ but less than a
third of that (averages = £0.26bn to £0.30bn)
Sources of data
£1bn?
Annual average loss [£bn]: financial
values
Annual average loss [£bn]:
economic values
N/A
1.281
N/A
1.1
0.491
0.261
0.360
0.192
Environment Agency NAFRA 2008
(adjusted by Area teams)
National Audit Office (2011)
EA residential property numbers
flooded (Harmar, 2011), grossed up
ABI press release (ABI, 2010) covering
1990-2009
ABI claims average 1998-2009
0.606
*
0.268
From residential-only figure of
From residential-only figure of
0.272
0.141
N/A
0.500
N/A
0.263
0.49
0.25 [0.26*]
0.30
with the NAFRA-informed IBM
result included
IBM risk profile (adjusted NAFRA model
to historic data)
‘Reversing’ WAAD calculations
Conclusion
No.of3:items
Theinlikely
Simple averages
bold (2AAD is £0.26significantnot
figures
only)
£0.30bn,
£1.0-£1.3bn
* Corrected in the Circulation Note to 0.322 and 0.26 to allow for insurance penetration
Counter-arguments
Conclusion No. 4: Counterarguments are at best weak and at
worst misinformed
You are ignoring climate change
Well, we cannot detect ANY ‘signal’ on rivers such as the Thames of
increasing flood flows and hence higher losses now to affect current AAD
Current floods are likely to be more damaging than floods 20-50 years ago, so
you cannot use data from the past (e.g. 1947 and 1953)
Yes: a good point BUT there has also been huge investment over that period
that should have drawn down losses!
You are missing the key “intangible” losses
True, but we ARE comparing like with like, as NAFRA ignores these too
You have ignored “surface water flooding” which is a major hazard
True: BUT insurance data include these in claims, so the amount remaining
from claims totals for NAFRA type fluvial/coastal floods is even less
Even a long record misses extremes that add significantly to AAD values
Well, we go back to 1947 and to 1894 (Thames). And Merz et al.’s (2009)
work in Germany shows that only 20% (2%) of AAD is generally attributable
to floods over a 100 (500)-year return period. Floods that are unlikely to
show up in a 50- to 100-year record will never add hugely to AAD.
1.2
0.8
Raw data from ABI
Deflated to economic values + 22%
(see text)
0.6
0.4
0.2
0
*
Penning-Rowsell, E.C. (2014) What do the 2013/14 floods tell us
about overall flood risk in England and Wales? Circulation, 121, 5-6
Caveat: the ABI
does not
represent the
whole market
(c. 82%)
£0.146
1
£0.147
£bn at 2010 prices (except 2011 to 2013/14
which are at prices then ruling)
Up-date
The Circulation* Note’s extension of
economic damages (residential only)
Up-date
Paul Samuel’s analysis of the Circulation
Note’s economic damages (residential only)
Conclusion No. 4b: Up-dating for
2013/14 floods, correcting one
small error, and a changed
residential/NRP ratio does not
change the results to any marked
extent
The
2007
flood
Up-dated residential
fraction of damages:
2000 (45.2%); 2007
(37.9%) & 2013/14
(64.9%). Weighted
mean = 41.8%.
Calculated Residential
AAD = £0.144bn
Total ADD
= £0.34bn
£0.25 [0.26*]
£0.30 billion
PS (12.6.2014): “I have played with the data and supposed 2007 would be the highest damage if we had 50 years of record. Assuming my use of the
Gamma function is correct (need to check this), this changes EAD to £144 M from £178 M to give you an idea of the importance of this particular
event in the bigger picture. I have ideas for other ways of exploring sensitivities, we should also explore some of the temporal and spatial differences
of the 2007 flooding to understand the impact of the event”
A ‘realist’ approach to the extent of fluvial and coastal
flood risk in England and Wales:
Conclusion No. 1: the model(s) appears
unstable and unreliable
Conclusion No. 2: some RASP/NAFRA
predictions look badly exaggerated
Conclusion No. 3: The likely AAD is £0.26£0.30bn, not £1.0-£1.3bn
Conclusion No. 4: Counter- arguments are
at best weak and at worst misinformed
Conclusion No. 4b: Up-dating does not
change the results to any marked extent
(maybe to £0.34bn)
Conclusion No. 5: This exaggeration
must not continue; we must be realistic
and honest about the risks that we face
2. The number of properties at risk of
flooding in England and Wales*
“The Environment Agency’s 2008 National Flood
Risk Assessment shows there are 2.4 million
properties at risk of flooding from rivers and the
sea in England”.
“Our preliminary assessment of surface water
flood risk also suggests that one million of these
are also susceptible to surface water flooding
with a further 2.8 million properties susceptible
to surface water flooding alone”.
“In all, around 5.2 million properties in England,
or one in six properties, are at risk of flooding”.
Environment Agency, 2009, page6.
Yalding, Kent, 2000
* Original analysis by Jane Fielding, University of Surrey
Table 1. Properties at flood risk from different
flood sources in England and Wales
Source of risk
England
(Properties)
No.
%
1,400,000
26.9
Fluvial and Tidal
only
Surface water
2,800,000
only
Fluvial & Tidal & 1,000,000
surface (all 3)
Total at risk
5,200,000
Source: Environment Agency
Wales
(Properties)
No.
%
123,000
34.5
53.9
137,000
38.4
19.2
97,000
27.2
100.0
357,000
100.0
Table 2. The number of properties in England
and Wales
England
Residential
TOTAL
Properties
(Census
2011) or
VOA
TOTAL
Properties
(CodePoint
®) Analysis)
TOTAL
Nonresid’ial
Wales
TOTAL
GRAND
TOTALS
Resid- Nonential resid’ial
22,063,400
1,734,790 23,798,100 1,302,700
104,720
1,407,420 25,205,520
23,068,604
1,135,822 24,204,426 1,385,847
+ 57,081
(excl PO
PO Boxes
boxes)
66,048
+ 1,942
PO Boxes
1,451,895 25,656,321
(excl PO
boxes)
24.2 million
1.5 million
25.6 m
Table 3. Properties at flood risk in England and
Wales (Environment Agency/Defra data)
ENGLAND (thousands)
Rivers and Seas
Surface
At flood risk
2,400,000
2,800,000
Total
5,200,000
Residential
Total at flood
risk
% at risk using
CodePoint®
estimates
Notes
Nonresident
ial
1,850,000 550,000
WALES (thousands)
Rivers and Seas
220,000
Residential
148,000
Nonresidential
60,000
Surface
Total
137,000
357,000
(+97,000)
8.02%
48.42%
21.48%
10.68%***
90.84%***
24.59%
One in
twelve
One in
two??
One in
five
One in
ten
Nine in
ten??
One in
four
Table 4. Properties at fluvial and tidal flood risk
(independent assessment, but using EA maps**)
England
Total
Properties
Properties
at risk
% at risk
Proportions
TOTAL
England
Residential
Nonresidenti
al
23,068,604
1,135,822
1,808,748
Wales
TOTAL
Wales
GRAND
TOTALS
Residential
Nonresidenti
al
24,204,426
1,385,847
66,048
1,451,895
25,656,321
146,693
1,955,441
142,078
14,037
156,115
2,111,556
7.84%
12.92%
8.08%
10.25%
21.25%
10.75%
8.23%
One in
thirteen
One in
eight
One in
twelve
One in ten
One in
five
One in
nine
Result: good agreement overall, although Non-Residential
** NAFRA based …
property numbers seem to be highly uncertain, and “surface
water flooding” is unverifiable (as yet). But ….
The Thames Estuary’s floodplain: “at risk”
• >1.25million people [TE2100 data]
• 400 Schools, 16 Hospitals
• £160bn Property
• International Habitats & Species
• Port of London generates £2.7bn/yr.
• City Airport
• Olympic site
- 30 Mainline Railway Stns
- 68 Underground & DLR Stns
- 8 Power Stations
• c. 520,000 residential properties ……
“at risk”, out of our 1,808,748
from our assessment (29%), and ...
Floodplain
The Thames Barrier: a
design standard of
effectively 1:5,000 years
… 29% of the properties
“at risk” have this
standard of protection.
Oxford’s flood risk
Fluvial/coastal
“Surface water”
flooding: 2.4m
(pluvial) flooding:
properties
2.8m properties
nationally ? nationally?
Central
London’s
“Surface
water
flooding”
0
South
Reading’s
“Surface
water
flooding”
You are here
“Surface
water
flooding”
at
Kingstonupon-Hull
“Surface water”
(pluvial) flooding:
2.8m properties
nationally?
Result:
Some quite serious
questions remain to be answered
here about the national ‘surface
water’ flood risk situation.
My conclusions
1.Exaggerated assessments of fluvial
and coastal risk have become
“embedded” in our thinking.
2.The situation is akin to a conspiracy to
exaggerate, fuelled by an upward
spiral of expectations of future risks
that have generated the substantial
increases in all flood-related budgets
that have occurred over the last
decade or so. We have all gained…
3. It is not a real conspiracy, in that
there is little actual conspiring, but it
resembles a collective myopia and
lack of critique driven by an inherent
satisfaction that the results show (or
purport to show) a level of risk that
attracts strong and widespread
public, political and financial support.
Member: Flood Hazard Research Centre http://www.fhrc.mdx.ac.uk
4. In my view, this is distinctly
Member: Oxford Water Security Network www.water.ox.ac.uk
Editor: Environmental Hazards (Taylor and Francis) http://mc.manuscriptcentral.com/ehaz
unsatisfactory.
Edmund Penning-Rowsell
Copyright (text) FHRC
Edmund Penning-Rowsell
Member: Flood Hazard Research Centre http://www.fhrc.mdx.ac.uk
Member: Oxford Water Security Network www.water.ox.ac.uk
Editor: Environmental Hazards (Taylor and Francis) http://mc.manuscriptcentral.com/ehaz
Copyright (text) FHRC