Storm Surge Prediction and its Impact on the UK Economy

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    Storm Surge Prediction and its Impact on the UK Economy

Summary of Impacts

    Impact                                                  Value
    Safeguarding the London Economy                         £94 million per flood day
    Safeguarding property in the Thames Estuary area        £2 billion per annum
    Giving confidence to future London investment           £2.1 billion per annum
    Value of human lives in the Thames floodplain           £31.25 billion per annum

Summary of Key Points

          NERC’s Proudman Oceanographic Laboratory (POL) is a world leader in storm surge
           modelling and in partnership with a number of other key organisations, it plays a critical role in
           the UK Coastal Monitoring and Forecasting (UKCMF) service.

          Storm surges are temporary increases in sea level caused by low atmospheric pressure
           combined with strong winds. Heavy rainfall, high tide and waves combine with storm surges
           to be capable of flooding entire coast lines.

          A North Sea storm surge in 1953 killed 307 people. In 2007 the worst storm surge in 20 years
           hit the coast of England. However damage and disruption was limited due to accurate and
           timely forecasts informed by NERC research which enabled effective and proportionate
           responses.

          Storm surges are likely to increase in frequency as global sea level is expected to rise by
           approximately a metre by 2100.

          Key partners with NERC are the MET Office, Environment Agency, Defra, the Scottish
           Environment Protection Agency and the Rivers Agency of Northern Ireland. The Environment
           Agency is the key user of research outputs.

          Storm surge modelling is fundamental in protecting the London economy and is worth £94
           million for each flood day. Since 1983 the Thames Barrier has been closed 107 times (as of
           January 2008). In 2001 the barrier was closed 15 times and is expected to be closed 30 times
           a year in 2030 in order to maintain the current standard of tidal defence.

          If NERC research helps to safeguard 1% of property in flood risk areas, this represents £2
           billion worth of property.

          A 5% fall in Foreign Direct Investment due to perceived flood risk would cost the London
           economy £2.1 billion per annum. NERC research gives confidence to London’s ability to
           withstand future flood events which supports FDI.

          The value of human lives safeguarded from flooding in the Thames floodplain is £31.25 billion
           per year.




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Introduction

This case study considers the impact of the storm surge modelling work carried out at NERC’s
Proudman Oceanographic Laboratory (POL) in Liverpool.1

It provides an overview of the scientific research, the funding inputs, research partners, industry
collaborations and the resulting socio-economic impacts.

POL is wholly owned by NERC and co-located with the University of Liverpool. It was formed in 1850
when its focus was on ship navigation and issues such as accurate time-keeping. It became a world
leader in tidal dynamics and currently has 137 staff and 25 PhD students. Today POL continues to
focus on tidal dynamics and the physics of shelf seas.

There are four strands to NERC research at POL:

             Ocean circulation and climate
             Physics of Shelf Seas
             Technologies to Support POL Science
             Hosting of the British Oceanographic Data Centre.

More information on POL can be found at www.pol.ac.uk.

Storm Surge Context
Storm surges are temporary increases in sea level caused by low atmospheric pressure combined
with strong winds. They are a critical component of total sea level during coastal flood events and
occur as storms push huge quantities of water towards the coastline. Heavy rainfall, rising tide, large
waves and storm surge elevation produce a destructive force that is capable of flooding entire coast
lines.

One of the most famous storm surges of recent times was the one associated with Hurricane Katrina
in 2005 which produced a maximum storm surge of 7.6 metres. Storm surges can be incredibly
destructive and are responsible for many deaths. For example, in 1970 a severe tropical cyclone hit
the coast of Bangladesh, drowning 300,000 people. Every tropical storm that hits the coast has the
potential to produce a storm surge, however not all storm surges rise to dangerous levels. Dangerous
storm surges are dependent upon a number of factors occurring at the same time.

The UK is not at risk from hurricanes however storms have resulted in destructive storm surges along
the east coast of England, for example, a North Sea storm surge in 1953 killed 307 people in Britain.
This disaster led to the development of the UK tidal gauge network. In 2007 the worst storm surge in
20 years hit the coast of England, peaking at 2.1 metres. However damage and disruption was
limited due to accurate advanced forecasts informed by NERC research.

Although destructive storm surges are less frequent in the UK than the USA for example, flood
defence measures such as the Thames barrier are used regularly during the year. Since 1983 the
barrier has been closed 107 times (as of January 2008). Before 2001 the barrier was closed three
times per year on average. However, in 2001 the barrier was closed 15 times and is expected to be

                                                            
1
 This report was produced for NERC by DTZ, a private consultancy. It does not necessarily reflect NERC's
opinions and policies.

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closed 30 times a year in 2030 in order to maintain the current standard of tidal defence2. It currently
costs £16,000 to close the Barrier on each occasion.

Global sea level is expected to rise by approximately a metre by 2100, which will change the
frequency and extent of coastal flooding. Higher sea levels will increase the importance of managing
the risks through better forecasting systems, which can take into account the science behind sea-level
rise, storm surges and inundation. In particular, effective warning systems for storm surge prediction
are essential in order to protect coastal communities and minimise economic loss.

Storm Surge Modelling
Storm surge modelling forms one part of wider NERC work on shelf sea circulation models at POL. In
partnership with the Environment Agency, Met Office, Defra, the Scottish Environment Protection
Agency and the Rivers Agency of Northern Ireland, NERC provides the coastal flood forecasts used
operationally across the UK.

The components of the UK coastal flood warning service are outlined in Figure 1, with NERC models
forming a key part of the model suite that runs four times per day at the Met Office. Storm surge
forecasting is aided by real-time sea level information from a network of 44 precision tide gauge sites
maintained and developed by NERC. This UK Coastal Monitoring and Forecasting (UKCMF) service
is owned and funded by the Environment Agency and costs £2 million per year to maintain.
Information from the service is ultimately provided to Environment Agency regional forecasters.

Figure 1: Components of the UK Coastal Flood Warning Service




Source: NERC’s Proudman Oceanographic Laboratory

                                                            
2
     http://www.environment‐agency.gov.uk/static/documents/Leisure/Project_Pack.pdf 

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NERC surge models predict the scale and timing of storm surges around the coast of the UK. They
rely on numerical weather prediction and high performance computers.

Storm surges combined with high tidal range provide the main driver of coastal flooding in the UK. In
the long term, the impact of rising mean sea level due to climate change will exacerbate the effects on
low lying coastal areas, particularly the south east of England – where more than 100,000 properties
are at significant risk of flooding3. In addition, some southern areas of the UK are actually sinking due
to land movement, again increasing the risk from storm surges.

Modelling a Storm Surge Event
In order to fully appreciate the impact of NERC’s storm surge research, it is useful to analyse how it is
put into practice in an actual event. In November 2007, the east coast of the United Kingdom had the
worst storm surge in more than 20 years. However, as a result of precautionary evacuations in East
Anglia and by raising the Thames Barrier, there were no fatalities or significant financial losses.

In a paper published in November 20084, the performance of the operational modelling system used
for surge forecasting was examined. Significantly, this found that the modelling system provided
accurate estimates of water levels at all east coast locations up to two days ahead of the event. The
research compared predictions from the modelling system with quality-controlled data from several
tide gauges and the key finding was that the surge was accurately forecast along the whole of the
UK’s east coast. The model slightly overestimated the peak of the surge at Sheerness but overall, the
research noted that the agreement with all observation was good.

As already noted, projected sea level rises up to 2100 will reduce the return period for any given
extreme sea level. This presents a challenge to flood warning systems, which will be required, more
frequently, to deliver accurate and timely predictions of coastal water levels to protect people and
property. In particular, accurate information on future sea levels is needed in areas such as the
Thames Gateway - which will see substantial development over the next 10-15 years, but which is at
risk from flooding.

NERC Research Partners/Collaborators
The storm surge modelling represents a number of key partners working together and these are
shown below. Much of NERC’s work on operational storm surge modelling is paid for by the
Environment Agency as the key government user. NERC and the Met Office work closely together to
develop and improve storm surge modelling.




                                                            
3
  Environment Agency (2009) “Flooding in England: A National Assessment of Flood Risk”. Available at:
http://publications.environment-agency.gov.uk/pdf/GEHO0609BQDS-E-E.pdf
4
 Horsburgh, K. Et al (2008) “Aspects of operational forecast model skill during an extreme storm surge event”,
Journal of Flood Risk Management (2008), 213-221.

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Figure 2: Partners and Collaborators 



Quantification of Economic Impact
Market Failure and Rationale for Storm Surge Modelling

When assessing the economic impact of NERC’s storm surge modelling work, it is useful to consider
the rationale for investing in the research. This can be done by considering whether a market failure
exists. Market failure is when the market, by itself, has not and cannot be expected to deliver an
efficient outcome. Thus, any research intervention must seek to redress this failure in the market.

There is no incentive for the private sector to develop and monitor storm surge models. Storm surge
events are infrequent and require expertise to predict, however the effects are devastating. The costs
of developing and maintaining the models combined with the uncertainty of capturing a return on the
investment mean the private sector is unlikely to invest. Many of the benefits are in savings to human
lives, as the 1953 UK storm surge disaster showed. The private sector is unwilling to invest in this
type of situation.

The benefits of protection from storm surges are for all of society (the UK tax payer) in terms of
protection of lives, property, supporting planning decisions (where development can safely take place)
and in advising where engineering works are needed to protect communities and businesses.

In particular, storm surge modelling has been fundamental in supporting the London economy. It has
done so, and continues to do so through the accurate prediction of severe storm surge events so that
steps can be taken to prevent loss of human life and moveable property. In other words, the
application of the research is all about avoidance of negative effects.




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The research is applied in the following ways:

Ongoing protection

The monitoring and forecasts of UKCMF allows up to 58 hours advance notice of a storm surge (with
an 18 hour window for evacuation to safeguard personnel in day light). This allows time for
evacuation of personnel, movement of valuable property to safe areas and, for London, closure of the
Thames barrier.

Informing the required future flood protection for areas such as London – TE2100

Established in 2002, the Thames Estuary 2100 project (TE2100) aims to develop a long-term coastal
flood risk management plan for London and the Thames Estuary led by the Environment Agency. The
key reason for developing TE2100 is outlined by the Environment Agency:

“When an area of low pressure, perhaps hundreds of miles across, moves eastwards across the
Atlantic towards the British Isles, it raises the level of seawater beneath it by up to a third of a metre. If
this 'plateau' of sea water passes north of Scotland and then down into the shallow basin of the North
Sea, perhaps further heightened by strong winds from the north, it can cause excessively high surge
tides in the Thames Estuary of up to 4 metres leading towards London. When a surge tide also
coincides with a spring tide (which occur twice monthly), flooding would be a serious possibility.”5

Important aspects of the TE2100 have been informed by NERC’s research in the area of storm surge
modelling. Being able to predict the required height of sea defences with any level of confidence is a
critical element of the work. As the November 2007 storm surge (discussed above) hit the east coast
of the UK, it was accurately predicted by POL and the evacuation of people and property took place.
While this event was not as severe as the 1953 event, the forecasts suggested that serious risk to
people and property was possible. The quantification of the value of the research can therefore be
estimated as follows6:

Safeguarding the London economy – The London economy is worth £230 billion7 per annum and is
the centre of government as well as many other sectors. For example, London accounts for more than
one third of total Gross Value Added (GVA)8 in the UK in the finance sector. London is low lying and
at particular risk of flooding from the Thames. Whilst the Thames Barrier and other flood protection
mechanisms are in place, it is critical that London should be able to operate, safe from extreme storm
surge events. POL provides the science to inform the forecasts. Work undertaken by the Environment
Agency9 has identified which parts of London are at risk from tidal flooding (see Figure 3).

                                                            
5
    http://www.environment-agency.gov.uk/homeandleisure/floods/38351.aspx
6
 This assesses the counterfactual – that is, what would have happened had the NERC investment not been
made? The calculation is therefore an additional benefit attributable to NERC and partners.
7
  Figure relates to London’s Gross Value Added (provisional estimate) in 2007. Sourced from “Regional, sub-
regional and local gross value added”, Office for National Statistics. 12 December 2008. Available at:
http://www.statistics.gov.uk/pdfdir/gva1208.pdf
8
  Gross value added is the difference between output and intermediate consumption for any given
sector/industry. That is the difference between the value of goods and services produced and the cost of raw
materials and other inputs used up in production.
9
 Environment Agency: TE2100 Plan – Consultation Document, April 2009. Available at : http://www.environment-
agency.gov.uk/static/documents/Research/TE2100_Chapter01-04.pdf

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Figure 3: Areas and Employment in London at risk from tidal flooding




Source: Environment Agency and Annual Business Inquiry – adapted by DTZ

Adding employment data from the Annual Business Inquiry10 shows that there are approximately 1.1
million people in London working in areas at risk from flooding. According to the Office for National
Statistics, GVA per head in London is £31,28011 - meaning the total GVA contribution of the 1.1
million people is £34.4 billion per year (£94 million per day). If POL advice safeguards this contribution
for only 2 days per year, it is worth £188 million per annum to the London economy.

Safeguarding property – Based on analysis undertaken by the Environment Agency12, over 300km
of roads and more than 500,000 homes are at risk in the Thames floodplain. Significantly, the
estimated value of property within this area is £200 billion. Even if the work by POL helps to
safeguard 1% of this property, this still represents £2 billion in property assets within the Thames
Estuary area.

Giving confidence to future London investment – As well as safeguarding the London economy,
the fact that there is confidence about London’s ability to withstand future flood events arising from
storm surges is a major factor in underpinning investment. Foreign Direct Investment is worth £42
billion in GVA to London per annum13. Were London to be perceived as at risk from flooding, it is
                                                            
10
  The Annual Business Inquiry is an employer survey (conducted by the Office for National Statistics) of the
number of jobs held by employees broken down by sex, full/part time and detailed industry.
11
         http://www.statistics.gov.uk/pdfdir/gva1208.pdf

12        12
        Environment Agency: TE2100 Plan – Consultation Document, April 2009. Available                 at   :
http://www.environment-agency.gov.uk/static/documents/Research/TE2100_Chapter01-04.pdf 
13
         London – Global City, International Business. DTZ, October 2006

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unlikely that foreign companies would invest there. POL therefore plays an important role in giving
confidence to future investment. Even a 5% fall in FDI due to perceived flood risk would cost the
London economy £2.1 billion per annum.

Value of human lives – The work of POL not only helps to safeguard the lives of people in London,
but also throughout the Thames Estuary area. To put this in context, the Environment Agency has
estimated that 1.25 million residents (in addition to commuters, tourists and other visitors) are at risk
in the tidal Thames floodplain14. Work undertaken by the Department for Transport15 has estimated
that: the average cost of one human fatality is £1 million; and the average cost of a serious injury to
one person is £150,000.

Taking these figures, it is possible to arrive at an estimate for the value of human lives being
safeguarded by POL’s storm surge research:

             Assuming 1% of the 1.25 million residents at risk were to be killed by flooding, this gives
              12,500 lives being lost – which translates into £12.5 billion in terms economic cost (12,000
              multiplied by £1 million.

             Assuming a further 10% of the 1.25 million residents suffer some form of serious injury, this
              gives 125,000 people – at an economic cost of £18.75 billion (125,000 multiplied by
              £150,000)

Taking the two figures outlined above, this gives a total economic value of £31.25 billion per year in
terms of human lives being safeguarded by the research16.

Informed decision making – As already noted, it costs £16,000 each time the Thames Barrier is
closed – money which will ultimately be provided by the UK tax payer. The UKCMF service is
becoming more accurate over time, which could help to reduce the number of times each year the
Barrier is closed. Even reducing this need 2-3 times a year could lead to savings of between
£32,000 and £48,000 – money which can ultimately be fed back into maintaining and improving
the UKCMF service. As noted by the Environment Agency:

“One of the main things that the surge model as an integral part of the UK Coastal Monitoring
and Forecasting Service (UKCMF), has assisted with over the last few years, is that as
confidence in the accuracy and understanding of the limitations of the model has improved
then operational cost savings have been made in the none closure of barriers as well as
flooding being avoided by closure of barriers. This is throughout the UK not just on the
Thames.”




                                                            
14
     Environment Agency: TE2100 Plan – Consultation Document, April 2009. Available                         at   :
http://www.environment-agency.gov.uk/static/documents/Research/TE2100_Chapter01-04.pdf 
15
    Department for Transport – Transport Analysis Guidance. TAG Unit 3.4.1, April 2009. Available at:
http://www.dft.gov.uk/webtag/docs/expert/safety-objective/3.4.1.pdf
16
   Please note – while this figure is similar to that produced by Government estimates on the cost of flooding in
London (£30 billion, Jane Kettle, EDIE 1/4/2005), it should be treated as a separate piece of analysis as it takes
into account a larger geographical area than only London.

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Wider Qualitative Impacts

Human Capital
NERC investment in this area helps to support 137 staff and 25 PhD students at POL. The expertise
of POL staff is used across the globe in Bangladesh, China and India, for example. POL is also
helping to monitor sea levels at strategic sites in the south Atlantic and across other British Overseas
Territories. In addition, following the 2004 Boxing Day tsunami which killed more than 230,000 people,
scientists at POL helped to develop and install a tide-gauge network around Africa to better monitor
sea levels in the Indian Ocean.

Impact on Policy

NERC research on storm surges has a significant impact on UK policy helping to inform new
legislation relating to the marine environment. Policy inputs include:

        The UK Marine Monitoring Assessment Strategy (MMAS)

        The EU Maritime Strategy

        The formation of the Marine Management Organisation.

Oceans 2025 is NERCs key strategic marine science programme and includes seven UK marine
centres including POL. Oceans 2025 aims to address three main challenges:

    1. Understanding the rules of ocean behaviour

    2. Monitoring long-term changes in the oceans

    3. Helping ensure sustainable use of marine resources.



Consultees and Reviewers
In order to produce this case study on the storm surge modelling work carried out at NERC’s
Proudman Oceanographic Laboratory, the following people were consulted and reviewed a draft of
the case study:

        Professor Andrew Willmott – Director, Proudman Oceanographic Laboratory

        Dr Kevin Horsburgh – Head of National Tidal and Sea Level Facility, Proudman
         Oceanographic Laboratory

        Angela Scott – Environment Agency.




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