RESILIENCE OF THE FOOD SUPPLY
TO PORT FLOODING ON EAST
COAST
DEFRA PROJECT FO0454
Sub-Annex 2
East Coast Tidal Flooding Scenarios
December 2015
Kamal Achuthan
Jenny Roan
Taku Fujiyama
1. Introduction
The project seeks to understand the resilience of the UK food supply chain in
response to a potential east-coast flooding event, which could severely impact on the
capacity of east coast ports. Almost 50% of UK imports including food and drink
supplies are handled by the east coast ports; if a major east coast tidal surge
disrupted the capacity of such ports for a sustained period (6-12 months), it could
have significant impact on the food supply chain. Therefore, it is critical to explore
and understand possible coastal flooding scenarios in order to inform sector
resilience plans to mitigate and respond to the risks to disruption in the food supply
chain. This report outlines two possible scenarios (a reasonable worst case and a
moderate case) for an east coast tidal surge that will form the initial basis to explore
the potential impacts to ports and the food imports they handle. The next phase of
the project will involve obtaining the input of key stakeholders to further understand
the impacts and will include the scenarios themselves being validated and refined as
needed.
2. East Coast tidal surge
A tidal surge (or storm surge as referred in Figure 1) is an abnormal rise in sea level
caused by high winds pushing the water surface towards the coast. When strong
winds combine with low pressure, which contributes to the storm raising the water
level, and coincide with high spring tides, it can cause serious coastal flooding (Met
Office1). The occurrence of such a tidal surge, its characteristics and impacts are
highly uncertain and it is therefore difficult to ascertain the vulnerable coastal areas
and the associated critical infrastructures. Tidal surges could happen across most
of the UK coastline; however an east coast tidal surge has the potential to cause
highest level of damage. The East Coast Flood Emergency framework published on
the 60th anniversary of the 1953 East Coast Flood summarises the reasonable worst
case east coast tidal surge scenario and its impacts. The report makes reference to
the Health and Safety Laboratory assessment that the worst possible coastal
flooding event (H19 as defined by the National Risk Assessment process) in the UK
would be a major east coast tidal surge event.
One of the major consequences of an east coast tidal surge would be the severe
damage it could cause to the ports along the east coast and disruptions to UK supply
chains. The major UK ports situated along the east coast account for nearly 50% of
UK port capacity. Nearly 40% of the food consumed in the UK is imported, the
majority via ports. While a healthy balance of domestically produced and imported
food acts to spread risk through a diverse supply base, this highlights the importance
of port resilience to UK food security. The east coast ports, being close to the major
Northern European ports, tend to handle the majority of the imports from the EU, of
which 60% are food commodities. It is expected that a major tidal surge could cause
significant damage to east coast ports and disrupt imports for a sustained period, up
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http://www.metoffice.gov.uk/learning/learn-about-the-weather/weather-phenomena/storm-surge
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to 6-12 months, which could severely disrupt food supplies to the UK. Hence, it is
important to consider such worst case scenarios, understand the consequences and
prepare to alleviate the adverse effects.
Figure 1 East coast tidal surge (Source: Met Office)
Figure 2 Coastline affected by east coast tidal surge
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3. Scenario Design
This project will rely on scenario based modelling to evaluate the consequences of
east coast tidal flooding events. The main reason for this is the uncertainties
associated with tidal surges. The levels of the tide and the severity with which it
would impact different regions of the coastline during a single event could vary
significantly. While it is generally understood, as illustrated in Figure 1, that as the
tidal surge moves south down the east coast could reach higher levels and thus
cause more flooding, the December 2013 east coast tidal surge was more severe on
the Humber/Lincolnshire coast than it was along the Essex or Kent coastline. There
are a multitude of weather related variables that cause these uncertainties in the
nature and the characteristics of the tidal surge itself. The widely agreed upon
characteristics of east coast tidal surges in UK are that they are most likely to occur
between October and March and that the affected coastline could stretch from
Northumbria to Kent, as shown in Figure 2. In addition, the impacts on shore side
infrastructure facilities will depend on their location in relation to flood levels and the
presence of natural and man-made flood defences. The Environment Agency’s flood
risk maps are the best available data on the areas that will be potentially flooded
during such an event.
3.1. Flood maps
The Environment Agency (EA) publishes flood risk maps showing zones that could
potentially be affected by flooding if a river rises above its banks or high tides and
stormy seas occur. The flood maps are designed to increase public, local authorities’
and other organisations’ awareness for preparing for flooding incidents or applying
planning permission (EA, 20112). They combine different sources from model and
survey data, including detailed computational modelling of the rivers and the sea, a
surface model of the ground, a study of estimations of the volume and frequency of
water flow down rivers, and records of previous flooding. The flood maps are
classified into two types: Flood Zone 2 and Flood Zone 3. The definitions of each
flood zone are displayed in Error! Reference source not found.. Flood Zone 3
represents the area that could be affected by flooding in general while Flood Zone 2
includes the additional extent of flooded areas that are likely to be affected by a
major flood. These flood maps overlaid on Department for Transport’s Deep Port3
system help identify critical infrastructures and particularly port infrastructures that
could potentially be inundated.
Table 1 Definition of Flood Zones
From the sea
From rivers
2
Flood Zone 3
0.5% (1 in 200) or greater probability of happening each year
1% (1 in 100) or greater probability of happening each year
Flood Map - Guidance for Professional Partners v3.0
3
Deep Port is a GIS database that holds spatial information on all maritime related transport
infrastructures including detailed information on UK port operations.
3
From the sea or rivers
Flood Zone 2
0.1% (1 in 1000) probability of happening each year
(a) Port of Felixstowe within Flood Zone 2
(b) Port of Felixstowe within Flood Zone 3
Figure 3 Deep Port showing the areas of ports within Flood Zones 2 and 3
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Error! Reference source not found. shows areas in the port of Felixstowe that are
within Flood Zones 2 and 3. It can be seen that if a flooding event of the 0.1% per
annum probability level occurred, the port of Felixstowe would be entirely inundated
and there it could be assumed that it would cause major disruptions to port
operations and its recovery could take a significant period of time, e.g. 6-12 months.
In the case of a flooding event with a 0.5% per annum probability, only a few areas
(less than 25%) of the port estate are inundated and therefore it could be assumed
that the disruption may be minor and the recovery quicker, e.g. 4-6 weeks However,
judging only from the flood zone maps it is difficult to justify this assumption as even
minor flooding could cause severe disruption to port operation if it affects critical port
infrastructure such as electricity and communication cables, quay cranes, and
hazardous goods storage areas or access to road/rail links. Hence for partial flooding
of port areas, a validation exercise with the respective port authorities is needed to
determine the potential disruptions to port operations and its recovery periods.
The other significant issue lies in the representation of the Flood Zones themselves.
In the case of Port of Boston (see Appendix), its area was shown as not inundated
for any flooding event, although the areas surrounding the port were shown within
Flood Zones 2 and 3. However, the December 2013 tidal surge flooded the port itself.
Verification with EA and DfT experts revealed that the flood zone outlines for Boston
did not include the effect of river flooding in some areas. However it could be
reasonable to assume that they could be the means of flooding at this port for a tidal
surge, and hence the Port of Boston could be considered as within Flood Zones 2
and 3 depending on the specific conditions. The EA’s accompanying policy
document (Policy number: 541_05) clarifies that some of the parameters on which
Flood Zones are assessed are continuously changing. The national level flood
outlines, though not able to forecast impacts with 100% accuracy, are fit for their
intended purpose i.e. for screening planning proposals. Hence, the flood zone maps
have to be used carefully in estimating the potential areas of inundations.
3.2. Scenarios
Having discussed all the uncertainties associated with tidal surges, it could be
concluded that it is difficult to design a likely scenario for an east coast tidal surge.
However, it would be prudent to design reasonable worst case scenarios based on
available data that could be further validated and refined with the involvement of
stakeholders. Hence, as a preliminary approach, the EA Flood Zone maps can be
used to estimate the port areas that will be inundated and to categorise disruptions
as minor, moderate or major depending on the percentage of port areas under
different flood zones as shown in Table 2.
Table 2 Categories of port disruption
% of port area under Flood Zone
<25
25-75
>75
Disruption to port operations
Minor
Moderate
Major
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Figure 4 UK ports that import food and drink (Source: Deep Port)
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As discussed in the previous section, it is difficult to assess damages and thus
disruptions to ports based on Flood Zone maps alone. A 25% inundation could
damage critical facilities of a port and thus cause serious disruption, while a 75%
inundation may cause little disruption to operations and hence at this stage the
disruption classification categories are only broad indicators. During the next phase
of the project these will be validated with specific port authorities to understand the
impacts along with periods of disruption to their operations for the different Flood
Zone maps. Error! Reference source not found. shows the locations of ports that
import food and drinks with the east coast ports that could potentially be disrupted by
an east coast tidal surge highlighted. Table shows a list of east coast ports that are
liable to be disrupted under different categories based on the initial assessment
using Flood Zone maps. The Flood Zone maps for the various east coast ports
extracted from Deep Port are presented in the Appendix.
Table 3 Disruption to ports under different flooding events
Port
Boston
Dover
Felixstowe
Goole
Great Yarmouth
Grimsby
Harwich
Hull
Immingham
Ipswich
London(Inc Tilbury)
Medway
Middlesbrough
Ramsgate
Tees
Thamesport
Tyne
Disruption for a 0.1%
annual probability flooding
event (Flood Zone 2)
Major
Moderate
Major
Major
Moderate
Major
Major
Major
Major
Major
Major
Major
Moderate
Moderate
Moderate
Major
Moderate
Disruption for a 0.5%
annual probability flooding
event (Flood Zone 3)
Major
Minor
Minor
Moderate
Minor
Major
Major
Major
Major
Major
Major
Major
Minor
Moderate
Minor
Major
Minor
The results show that almost all of the east coast ports would be either majorly or
moderately disrupted by a 0.1% annual probability flooding event except for the port
of Tyne. It is also assumed that for such a worst case flooding scenario both majorly
and moderately disrupted ports would be unable to operate for longer periods (6-12
months). This scenario, hereafter Scenario 1, would have serious implications for the
UK food supply chain as almost 50% of traffic is handled by these ports.
In a 0.5% annual probability flooding event, on initial analysis many of the ports may
have only minor or moderate disruptions. Thus this event, hereafter known as
Scenario 2, will be the “moderate” case scenario that considers more likely
disruptions at a lower, albeit still significant, impact level. It could be assumed that
with minor disruption the major east coast ports such as Dover and Felixstowe may
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recover and return to normal service levels within days. However, this moderate
case scenario, based on the EA Zone 3 map, will require further validation with port
stakeholders to gain further understanding of the possible impacts on port
infrastructure and subsequent recovery periods. Considering the level of associated
uncertainties, it is likely that Scenario 2 will employ sub-scenarios to capture the
variations. As this project will extensively use simulation models to understand the
consequences to food imports, these variations can be considered and analysed.
Based on the above discussion, this project will focus on the two scenarios as
summarised in Table 4.
Table 4 Port flooding scenarios
Flooding
Ports affected
Damage/Severity
Period of disruption
Scenario 1
All east coast ports
Complete inundation of
most ports causing major
disruption
6-12 months
Scenario 2
Some east coast ports
Uncertain (To be validated
using expert stakeholder
interviews/focus groups )
Weeks to months depending on
damage/severity
4. Conclusions and further work
The two scenarios designed will form the initial basis for the study, to explore the
resilience of the food supply to port flooding on the east coast. Scenario 2 needs
further validation with port stakeholders and will have refinements to consider the
variability of port disruption and damage, period of disruption, etc. Based on these
scenarios, the next phase of the project will analyse the categories/quantities of food
commodities imported by disrupted ports and their UK production and consumption
rates to determine the critical commodities that this work will focus on.
Both the scenarios will lead to the re-routing of ships to unaffected ports. In Scenario
1, ships normally arriving at affected ports will look for alternative unaffected ports
along the South and West Coast as even major Northern European ports may not be
operational. The decisions to be made on alternative ports will depend on many
factors and most importantly the capacity/capability of alternative ports and the
associated transport systems, and the costs incurred by key supply chain
stakeholders such as shipping companies, freight forwarders, importers and retailers.
However, there would be significant bottlenecks due to the lack of capacity at
alternative ports and all imports to the UK would be disrupted in Scenario 1. In
Scenario 2 there may be alternative ports fully or partially operational along the East
coast and hence re-routing may not cause significant disruption to supplies. This will
depend on which ports will be disrupted and likely recovery periods. These options
will be discussed with key stakeholders and experts to arrive at possible re-routing
scenarios before being tested using models to determine the consequences.
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