Coastal Change and Coastal Processes

1. Coastal Processes
Bill Cooper
2015 Severn Estuary Forum
29 September

2. 1
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

3. 2
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)

4. 3
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.)

5. 4
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

6. 5
What we think we know
Getty Images
AM 28 September 2015
-0.1
0.0
0.1
13.6
13.8
14.0
14.2
14.4
14.6
14.8
2005 2010 2015 2020 2025 2030
Amplitudefactor
AvonmouthTidallevel(mCD)
Year
Vernal Equinox Spring Equinox Lunar nodal amplitude

7. 6
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

8. 7
Jet Stream
Long-term average
climatology for January
(1981 to 2010)
January 2014

9. 8
Low Pressure on 12 February 2014

10. 9
Observed wind speeds across UK
Gusting 83 knots at Mumbles
Hurricane force winds

11. 10
0
10
20
30
40
50
60
70
01/01/14 11/01/14 21/01/14 31/01/14 10/02/14 20/02/14
WindSpeed(knots)
5 Feb
15 Feb
Observed Winds January and February 20014
1 Feb
8 Feb
12 Feb
3 Jan

12. 11
Observed Waves January and February 2014
0
1
2
3
4
5
6
7
8
01/01/14 11/01/14 21/01/14 31/01/14 10/02/14 20/02/14
WaveHeight,Hs(m)
Scarweather Weston Hinkley
1 Feb
8 Feb
12 Feb
5 Feb 15Feb
3 Jan

13. 12
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 2014
8 February 2014
9 December 2007
28 October 1996
5 January 1991
26 November 2000
7 December 2006
3 January 2014
5 February 2014
10 March 2008

14. 13
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.

15. 14
Acknowledgements
Thanks to information from:
 Met Office
 Channel Coastal Observatory
 Tidal Lagoon Power
 WaveNet

16. Thank you for your attention
bcooper@abpmer.co.uk