Coastal Processes

Bill Cooper

2015 Severn Estuary Forum

29 September

2

ABPmer – brief history

Established in 1950 as the Hydraulics Research Station for government owned British Transport Docks Board (BTDB)

BTDB privatised to become Associated British Ports (ABP) in 1981, owner and operator of 21 UK ports, 5 of which in South Wales

Research Station became ABP Research & Consultancy Ltd in 1985

Re-branded to become ABP Marine Environmental Research Ltd in 2002, short name ABPmer

ABPmer remain as wholly owned subsidiary of ABP Holdings Ltd

2015 is our 65th year since formation

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Coastal Processes

(My) definition:

Understanding the naturally occurring Physical Activity in the marine environment which can affect our coasts

The interaction of weather and the sea that creates waves and surges

The rise and fall of the sea by tides

The movement of the sea (driven by waves, surges and tides) and conditions that can create sediment transport

The balance between losses and gains in sediment transport that can change our coasts (geomorphology)

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What we think we know

Physical Activity driven by cycles and trends:

Cycles Gravitational pull of planets (e.g. sun and moon) creating tides with

daily, monthly, annual, decadal periodicity Seasonal cycles (sun) North Atlantic Oscillation (link with sun activity, jet stream behaviour)

Trends Climate change projections (global warming from sun - leading to

increases in mean sea level, etc.)

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What we think we know

2015 is a notable year for big tides – peak of 18.6 year lunar nodal cycle

3 events close to HAT – 21 February, 22 March and 29 September

117 events greater than MHWS, compared with 74 in 2006

Getty Images

AM 28 September 2015

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What we think we know

Getty Images

AM 28 September 2015

2005 2010 2015 2020 2025 20300.0

2.0

4.0

6.0

8.0

10.0

12.0

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.510.0

Vernal Equinox Spring Equinox Lunar nodal amplitude

Year

Avon

mou

th T

idal

leve

l (m

CD)

Ampl

itude

fact

or

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What we are still learning

Winter Storms December 2013 to February 2014:

Exceptional sequence of severe conditions

Unusually strong North Atlantic Jet Stream

Storm tracks that passed at relatively low latitudes

Key events for the South West occurred in January and February 2014

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Jet Stream

Long-term average climatology for January

(1981 to 2010)

January 2014

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Low Pressure on 12 February 2014

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Observed wind speeds across UK

Gusting 83 knots at Mumbles

Hurricane force winds

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01/01/14 11/01/14 21/01/14 31/01/14 10/02/14 20/02/140

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20

30

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Win

d Sp

eed

(kno

ts)

5 Feb

15 Feb

Observed Winds January and February 20014

1 Feb8 Feb

12 Feb

3 Jan

12

Observed Waves January and February 2014

01/01/14 11/01/14 21/01/14 31/01/14 10/02/14 20/02/140

1

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Scarweather Weston Hinkley

Wav

e He

ight

, Hs (

m)

1 Feb8 Feb

12 Feb

5 Feb 15Feb3 Jan

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What we are still learning

Sequence of 5 storm events in close succession during February 2014

Highest recorded wind speed and largest waves observed on 12 February

From “offshore” hindcast (last 35 years up to end of 2014) top 10 largest wave events occurred on:

Redefining Extreme Value Analysis estimates?

12 February 20148 February 2014

9 December 200728 October 1996

5 January 199126 November 20007 December 2006

3 January 20145 February 2014

10 March 2008

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What we are still learning

Succession of large storms of such high magnitude without intervening periods for recovery led to dramatic coastal change at rates not previously thought possible, especially on westerly facing beaches, e.g. dunes at Berrow receding by 20 to 30 ft.

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Acknowledgements

Thanks to information from:

Met Office Channel Coastal Observatory Tidal Lagoon Power WaveNet

Thank you for your attention

bcooper@abpmer.co.uk