Supplementary content to the description of Withernsea south in the terminal groyne effect page.
1968
The most recent seawall extension to the Withernsea frontage was completed. Built of reinforced concrete, the new revetment followed the course of a setback in the cliff line caused by the terminal groyne effect at the south of an earlier section, constructed in the 1920s.
1981
In order to address setback and possible outflanking, 29 metres of rock armour were installed at the cliff foot beyond the seawall.
1995
Again to counter setback, a further 25 metres of rock were added. At the same time, a shore-parallel breakwater, also of rock, was positioned some 30 metres seaward of the extensions.
1998
Once more, setback became evident, and rock armour was extended by another 60 metres. The work was treated as urgent.
▲ The rock extensions of 1981, 1995, and 1998, totalling 114 metres in length. Note the parallel breakwater to seaward. EP87 is an erosion post from which cliff loss was previously measured [Google Earth: 2003].
▲ Where the seawall ends (and the rocks start) [13 June 2018].
2005
This time, a 95 metre length of rock was installed, not directly at the cliff foot but offset by a gap of approximately 15 metres. The 1995 breakwater was removed.
▲ Offsets are introduced as a means of preventing revetments being undermined in the event of outflanking. Hornsea and Mappleton defences also include an offset design. In the picture, there is a small fall of cliff material [13 June, 2018].
▲ The 2005 extension (slightly paler grey), two years after installation [Google Earth: 7 May 2007].
▲ The 2005 extension, fourteen years after installation, demonstrating a convincing example of the terminal groyne effect [Google Earth: 21 September 2019].
![Withernsea south rock extensions 1981 to 2005 [Internet Geography]](images/TGE-WS-4.jpg "Withernsea south rock extensions 1981 to 2005 [Internet Geography]")
▲ Aerial view of extensions established 1981 to 2005. The setbacks are distinct [Internet Geography, Withernsea Photos no. 12].
2020
Completion of the South Withernsea Coastal Defence Scheme 400 metre extension, with the rock added in 2005 being realigned at the cliff foot. The last 100 metres is, as before, offset.
▲ The project continued during COVID restrictions [20 May 2020].
![aerial image [Internet Geography: 17 December 2020]](images/TGE-WS-7.jpg "aerial image[Internet Geography: 17 December 2020]")
▲ Entire rock extensions. The fence at the lower left in the picture marks the boundary of the town of Withernsea [Internet Geography, 17 December 2020].
▲ Southern end of the 2020 extension showing offset and cliff loss [20 December 2022].
any more?
“It should...be noted that ERYC [East Riding of Yorkshire Council] has no intention to extend the...line of defence further to the south beyond the
boundary of Withernsea...”
Report: South Withernsea Coastal Defences, 15 February 2019, 16.3.1, p96.
Page prepared by Brian Williams, June 2025.
