Storm Event

This event preceded the severe wave event at Chesil Beach in February 1979 – surge and percolation flooding

Severity ? 4

Source

The storm developed along the eastern US seaboard during 10th February 1978, following a north-westerly track before eventually combining with a larger depression over the central Atlantic. By 13th February, a large area of low pressure extended over the northern North Atlantic, deepening to below 960 mbar and producing south-westerly winds over the English Channel.

There is no local sea level data available at the time of this event. This event occurred during spring tides.

Wave heights exceeded 4.5 m at a period of around 12 seconds (Frampton, 1997). This type of combined wave and surge event was thought to have a return period of between 1 in 5 to 1 in 10 years (e.g. Frampton, 1997).

Pathway

Overtopping was the primary flood pathway during this event, most notably at Chesil Beach. At the junction of the sea wall and Chesil Beach there was overtopping was extreme, resulting in shingle overspill (Frampton, 1997). The beach ridge itself was not breached. In parts of Chiswell, the flood water reached a depth of 1.2 m.

Receptor and Consequence

This event was associated with coastal flooding along parts of the English Channel, most notably in Portland (Met Office, 1978; Zong and Tooley, 2003). According to West (2014) and references therein, the overtopping at Chesil Beach was the worst in several years. The road adjoining the main island was partly washed away, exposing underlying electricity and gas pipes. The damages here during this event (and subsequently the event to occur 3 months later in February 1979), resulted in over £5 million in investments to improve defences at Chesil.

References

  1. Frampton, S., 1997. Managing the Wessex Coast: The Chesil sea defence scheme. Geography Review, 10(4), pp.8–10
  2. Met Office, 1978. Monthly Weather Report of the Meteorological Office. Monthly Weather Report, 95(12). Available at: http://www.metoffice.gov.uk/learning/library/archive-hidden-treasures/monthly-weather-report-1970s
  3. Zong, Y. & Tooley, M.J., 2003. A Historical Record of Coastal Floods in Britain: Frequencies and Associated Storm Tracks. Natural Hazards, 29(1), pp.13–36. Available at: http://link.springer.com/article/10.1023/A%3A1022942801531 [Accessed March 5, 2015].
  4. West, I.W., 2014. Chesil Beach -Hurricanes, Storms, and Storm Surges. Geology of the Wessex Coast of Southern England. Available at: http://www.southampton.ac.uk/~imw/chestorm.htm [Accessed March 8, 2015]