East Yorkshire coastal erosion

hotspots


Created by Brian Williams in September 2012.
Revised July 2016.




 Holderness location

This page considers erosion hotspots in the context of the glacially deposited coastline of East Yorkshire, the greater section of which is known as the Holderness coast.






definition

A coastal erosion hotspot, otherwise written hot-spot or hot spot and very occasionally abbreviated to EHS, may be regarded as a location along a designated stretch of receding coast where cliff loss is reliably measured over a period of time as being significantly above the average for that length of coast.




causes

Any natural or human action that brings about a local reduction in beach level is almost certain to produce an erosion hotspot. Two processes can be observed to do this. Different in origin, one static and the other dynamic, they sometimes act together.


1. terminal groyne effect
The construction of defences against the sea in order to reduce erosion invariably results in an increase in the rate of cliff loss downdrift of the installation. This is called the terminal groyne effect (TGE). Hotspots caused by the terminal groyne effect are associated with particular locations.


 link to the terminal groyne effect page


2. sediment segmentation
Material which forms the beach is called beach sediment, a broad term for sand of all grades, for shingle, pebbles, cobbles, and rocks. Sediment is gradually driven down the coast by the action of sea current and tides. It moves not as a whole but in segments, or bodies. Depletion of sediment as one body gives way to another allows waves to reach the base of the cliff more frequently and with greater energy, often creating erosion hotspots.


 link to the sediment segmentation page




tracking hotspots

Monitoring of East Yorkshire coastal erosion takes place at the cliff top, twice a year. By making use of collected data, it is possible to track erosion activity, including hotspots. Below are some examples.

The tables display cliff loss in metres. Cells are colour graded for all values above coastal average – the darker the fill the greater the erosion.

Data for the entire coast is available from the following sheets:
the first ten years, 2003-2012 spreadsheet pdf
the last ten years, 2006-2015 spreadsheet pdf





Skipsea Withow

 Skipsea Withow hotspot migration example map

Shown on the map is the stretch of coast south of Skipsea towards Skirlington, passing Skipsea Withow SSSI (Site of Special Scientific Interest). Arrows indicate where monitoring profiles 26 to 30 intersect the cliff line, at 500 metre intervals.

 hotspots table 1: profiles 26-30 seasons 2008-2012

It can be seen from cell shading in the table how exceptional cliff recession – that is, a hotspot – has migrated southwards along the coast, at roughly half a kilometre per year, over a five year period.

A visual idea of the erosion process may be had from the opening trio of pictures at the Skipsea Withow page, taken close to the Profile 27 intersect, and from the image below, where mudballs and a thin beach just south of the Withow site indicate high erosion activity [26 May 2013].



 Skipsea Withow, East Yorkshire (21)




Tunstall to Withernsea

A further example of hotspot movement is captured in the table below.

The path of severe cliff loss is imprinted across twenty seasons (ten years) as it travels five kilometres from the now truncated Pastures Lane, Tunstall (Profile 79), across Sand-le-Mere (profiles 82 to 84) and Waxholme (profiles 86 to 87), to approach the Withernsea defences.

Evidence of the course of two other movements appear in the table. From a fixed point on the cliff top, recession is seen to occur in cycles.


 hotspots table 2: profiles 79-89 seasons 2004-2013

 Pastures Lane, Tunstall: 6 May 2013
Pastures Lane. Once a link between the communities of Tunstall and Hilston, the route along the cliff top has disappeared within the last decade [6 May 2013].
 beach below Pastures Lane, Tunstall: 28 Septemner 2013
Beach below Tunstall. Another characteristic hotspot scene. Here, an exposed clay platform is breaking up to form mudballs [28 September 2013].
 gap at Sand-le-Mere
Sand-le-Mere. Site of the lost mere in the name (cf. Skipsea Withow), this low lying section of coast is particularly vulnerable to the effects of erosion events [25 June 2013].
 Withernsea defences compartment #1
A volumetrically low sediment compartment at Withernsea north coincides with the arrival of an erosion cycle [20 November 2014].




Withernsea to Easington

The length of Holderness coast from Withernsea to Easington gas terminal contains within it a marked contrast in erosion activity.

At the northern end, the cliffs south of Withernsea are, for about four kilometres or so, subject to extreme erosion. Because of the number of extensions added to defences protecting the town from the sea – the most recent in 2005 – the section provides an excellent illustration of the terminal groyne effect (TGE pictures).

A little north of The Runnell, Holmpton, 18.84 metres were lost at Profile 99 through the summer of 2007, representing a record seasonal value for the East Yorkshire coast since comprehensive monitoring began. Other exceptionally large losses can be seen in the data.


 hotspots table 3: profiles 94-109 seasons 2004-2013

Conversely, the southern end of the same stretch of coast experiences very little recession over the span of the table. This part includes Dimlington High Land, another SSSI (video scan, 11th August 2014: .mov, .wmv, .mp4).

The thick, often contorted deposits of till are considered to be a push moraine, and the land is understood to have once risen even higher to the east before being consumed by the sea.

This section does of course experience loss over time but material released from the cliff by heavy erosion in the northern section has offered some protection.


 Intack Farm (site of), Hollym: 5 July 2013
Site of (the previous) Intack Farm, Hollym, built in the 19th century, dismantled before it could fall over the edge [5 July 2013].
 close to intersect of Profile 102, Holmpton: 20 April 2013
The cliffs become higher south of Holmpton and may for a period absorb some hotspot movement [20 April 2013].
 ord system (part) at DHLZ: 31 August 2013
High sand ridge and deep runnel, part of an ord system, passes the Three Sisters at Dimlington [31 August 2013].
 differential erosion at Hollym: 13 June 2013
Differential erosion of till units produces a ‘shelf’ at Hollym [13 June 2014].




Hornsea to Aldbrough

Finally, an example of a data table prepared for an ongoing hotspot study.

Cells given a yellow fill represent the migrationary course of a dynamic erosion hotspot which is seen in the table to begin at the south of the Hornsea defence system and later to traverse the defences at Mappleton. Although the table uses data from the current monitoring profile system, readings from the previous erosion post arrangement allow migration to be tracked back to 1984, when the hotspot was opposite Skipsea.

Hornsea and Mappleton are sites affected by the terminal groyne effect, which is responsible for potentially increasing the rate of erosion downdrift of impediments to beach movement and thereby activating a static hotspot. There is some suggestion in the table that incidents of cliff loss are more widespread in the section from Hornsea to Mappleton and for a couple of kilometres below (i.e. south of) Mappleton.

Unfilled cells flanking and separating yellow fills denote that no loss is recorded. Cells in grey-blue mark the paths of two other hotspot migrations, one preceding and the other following the subject (for clarity, values are omitted).

Average losses at undefended cliffs for the coast as a whole over the last ten years of the table are 0.58 metres and 1.15 metres, autumn and spring respectively.


 hotspots table 4: profiles 44-67 seasons 2001-2015

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