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Coastal flooding, 1607 floods, recent
storm surges and weather events in
the Severn estuary
Dr Kevin Horsburgh
Head of Marine Physics, National Oceanography
Centre
23 September 2011
National Oceanography Centrefrom coast to deep ocean
Waterfront Campus, Southampton Joseph Proudman Building, Liverpool
Vision: The National Oceanography Centre will, by 2015,
be recognised as the world-leading Centre for integrated ocean sciences and technology".
Some key facts
Owned by the Natural Environment Research Council (NERC)
• Based in two sites at Southampton and Liverpool
• 560 NERC staff (>200 scientists and technologists)
• £52 million annual budget (including capital)
Facilities directly managed for NERC• Royal Research Ships, James Cook and Discovery
• National Marine Equipment Pool
• British Oceanographic Data Centre
• Permanent Service for Mean Sea-level
National Capability Facilities
Global-class Research Vessels National Marine Equipment Pool and seagoing technical support
British Ocean Sediment Core Research FacilityPermanent Service for
Mean Sea Level
National Oceanographic LibraryNational Tidal and Sea-level Facility
British Oceanographic Data Centre
Independent scientific advice
Global mean sea level rise
Storm surge hypothesis for the 1607 flood
Storm surges
• Deviations from
predicted tidal heights
are mainly due to the
effect of the weather on
the sea surface
– Low atmospheric
pressure
– Strong winds
• Storm surges are
devastating, and cause
loss of life
The flooding of the Bristol Channel in 1607
• At about 0900Z, on 30 January 1607, the lowlands surrounding the
Bristol Channel suffered the worst coastal flooding on record
• The flood waters caused extensive damage in Bristol, the Somerset
levels, Barnstaple and places on the Gwent levels
• Its geometry, orientation with
respect to prevailing storms, and
exceptional tidal range make the
Bristol Channel and surrounding
regions susceptible to flooding
• About 44 square miles (120 km2)
of Somerset are at or below sea
level, a fact that inevitably gives
rise to inundation
• Similar topography on Welsh
side
• A flood risk management
document for the Environment
Agency refers to severe
historical flood events in 1672,
1770 and 1809
Taunton to
Glastonbury road
in flood (2000)
Bristol Channel tides• The Bristol Channel has the world’s second highest tidal
range:
– Bay of Fundy, Novascotia 15.4 m (Spring range)
– Bristol Channel 12.6 m
• Gulfs like the Bay of Fundy and the Bristol Channel are
known as quarter-wave resonators. They dimensions are
very favourable to amplification of any ocean wave (e.g.
tides)
ocean tide
head of gulf
amplification
l
Real time data span selector
• The tide of January 1607 was the largest in a century
• Tidal amplitude was 7.86 m which occurred at 0900h on 30 January 1607 (new style)
• Times of exceptional tidal forcing tend to recur every 4-5 years
• The largest tide at Avonmouth this century was 7.78 m on 20 March 2007
But the yeere 1606, the fourth of King James, the ryver of Severn rose upon a sodeyn
Tuesday mornyng the 20 of January beyng the full pryme day and hyghest tyde after
the change of the moone by reason of a myghty strong western wynde.
John Paul, Vicar of Almondsbury, 26 January 1606 (Old Style).
This storme begane at 3 of clock in the morning and continue tyll 12 of clock on the
same day.
Barnstaple Parish Register, 1607
Source/
Reported weather
Chap-book by Edward White Stormy
Puritan pamphlet by William Jones Vaguely implies fine weather
Anonymous pamphlet Stormy
Camden’s Brittania Stormy
Walter Yonge’s Diary (1848) Stormy
Barnstaple Parish Register Stormy (see text box)
Almondsbury Parish Register Stormy (see text box)
Arlingham (Glos) Parish Register Stormy
Stow (1631) Stormy
Historical sources of information
1 “A true report of certaine wondefulle
overflowings…”
Chap-book by Edward
White
The Mirror?
2 “God’s warning to his people of
England…..”
Puritan pamphlet by
William Jones
The Mail?
3 “Lamentable Newes out of
Monmouthshire in Wales….”
Anonmymous pamphlet The Sun?
4 Brittania William Camden The Telegraph?
5 Stow’s Chronicle The Times?
6 The diary of Walter Yonge Spectator?
Storm surges in the Bristol Channel
• Tidal curves for Avonmouth, Newport and Hinkley Point were calculated
• Surge (from 27 Oct 2002) of amplitude 2 m was added to the tidal curve over a cycle centred on high water, plus 0.3m for wave set-up
• The water level was input to a flood plain inundation computer model
• Even allowing for topographic changes, the inundation of 30 January 1607 could have been brought about by a more modest surge than that selected here
The Lisbon 1755 earthquake and tsunami
• The great earthquake
of 1 November 1755
(~8.5 Ms) destroyed
the city of Lisbon
• Waves of over 10 m
were reported in Cadiz
along North African
coastline
• Evidence of waves 2-3
m with correct periods
in Mounts Bay,
Cornwall Copper engraving of Lisbon harbour (J
Kozak collection)
Run 26 - Bristol Channel
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 50 100 150 200 250 300 350 400 450 500
Node number along section
Ma
xim
um
tsu
na
mi
wa
ve h
eig
ht
(m)
Ten
by
Mil
ford
Hav
en
Car
dif
f
Lla
nel
li
Sw
anse
a
Av
on
mo
uth
Min
ehea
d
Ilfr
aco
mb
e
Bu
de
Further flooding events of 1607
• According to the same
historical sources, regions
in East Anglia flooded on
the same day – (two
tsunamis would certainly be
a warning from God)
• The 1607 event reminds us
of the destructive power of
storm surges
• Scientific effort goes
constantly into the
improvement of surge (and
tsunami) forecasting
systems
Components of the UK coastal flood warning system
National tide
gauge network
15° real-time
data
Met Office
0.11°atmospheric
model
0.22°ensemble
atmosphere
3rd
generation
wave model
NOC
Tide-surge
models
Surge
ensemble
Flood
Forecasting
Centre
24/7/365
Environment Agency
Regional forecasters
(Wave transformation and
overtopping models)
EMERGENCY
RESPONSE
UK operational storm surge modelling system
What caused the flooding in 1607?
• The balance of evidence is that the event
was a storm surge on top on an
exceptionally high tide
• The majority of the historical writings imply
a time of great storminess and the same
conditions were reported widely across
Britain
• The villages affected correspond to those
that suffer during floods today
Meteotsunami
– 27 June 2011
Weather patterns for 1607• The 16th and 17th centuries appear to have been
windy. Lamb (1977) records 116 North Sea flood events between the years 1500-1599 and 128 events for the 17th century. This number then diminishes to 68 for the years 1700-1799
• One climatic reconstruction for 1596 suggests constant gales for western Britain as a result of enhanced variability of temperature
• One serious candidate for the windy conditions would be the displacement southwards of the atmospheric jetstream, causing a corresponding shift in depression tracks to lower latitudes than now (i.e. Britain would receive ‘Icelandic’ weather)
Sheerness
Lowestoft
Immingham