Watchet Coast At Threat
Unsustainable coastal developments in Watchet, Somerset puts an internationally important site at risk
Watchet: A Harbour Town
Watchet is a picturesque seaside town with an active marina, situated on the Somerset coast just 10km east of Minehead.
With a population of approximately 3,500, Watchet is a quiet but vibrant county town. However, music festivals, carnivals, fossil collecting and an esplanade overlooking the historic harbour draws tourists to enjoy the area every year.
Watchet has its roots in trading and maritime activities, with notable historic exports including coins, alabaster (gypsum) and lime. In addition to these trades, the famous West Somerset Mineral Line (built 1857-1864) terminated in Watchet, bringing iron ore from the Brendon Hills for export to Wales.
An Impressive Coast
The coastline immediately north of Watchet draws the attention of locals, artists, tourists and academics who are enticed by the beautiful views and spectacular cliffs.
From Blue Anchor to Lilstock, the coastline has been recognised by Natural England (the government's advisors for the environment in England) as hosting exceptional rock outcrops, and has subsequently been protected as a designated Site of Special Scientific Interest .
Blue Anchor to Lilstock Coast SSSI
The cliffs and foreshore surrounding Watchet are an important part of the Blue Anchor to Lilstock Coast SSSI, exposing incredible outcrops of Lower Lias limestones and shales (approximately 200 million years old), in addition to the bright red cliffs of ~230 million year old Triassic mudstones and alabaster.
The scale and quality of these exposed rock successions are of international importance showing some of, if not the best examples of Rhaetian to Lower Lias stratigraphy in northwest Europe.
For these reasons, the cliffs and foreshore were designated as a SSSI in 1986.
Why Designate a Site?
Sites that are identified as having national importance can be notified as a statutory site and subsequently offered legal protection through the Wildlife and Countryside Act 1981 (as amended). This includes protection from damaging activities including quarrying, building developments, coastal defence works or excessive fossil collection.
By designating an area as a Site of Special Scientific Interest, Natural England aims to enhance and conserve the area for future generations.
Geology with Inter-Planetary Importance
The remarkable exposures of red Mercia Mudstone streaked by white gypsum veins are not only of local, regional and international importance, but also of inter-planetary significance.
Scientific study of the geology at West Cliffs, Watchet has led to the exposures being used as an analogy to sediments found in Gale Crater on Mars, 33.9 million miles away.
A paper published by The Meteoritical Society in 2016 describes how the geology of West Cliffs has aided researchers in developing a better understanding of the possible presence of water on Mars. This is in conjunction with other researchers who have used Watchet as a 'test bed' for developing novel space craft instruments .
Watchet Coast: A Site Under Threat
An outline application made to Somerset West and Taunton Council (SWaT) in April 2021, proposes the development of 136 new dwellings on Cleeve Hill, Watchet. This highly controversial development has received backlash from the public due to worries about:
- Increased traffic and congestion along Cleeve Hill and through Watchet
- Increased pressure on pre-existing infrastructure and services
- The development's close proximity to the fragile West Cliffs
- Proposed re-alignment of the B3191 road close to the cliff edge
The easily-erodible geology observed in the cliffs to the west of Watchet Harbour extends below the Cleeve Hill site. This geology is highly susceptible to weathering and erosion, and as a result the ever-changing coastline has encroached to within meters of the B3191 and the Cleeve Hill site itself.
Cleeve Hill Road (B3191). Guard rails separate the busy B3191 from the cliffs and foreshore below.
Development Along the Foreshore
With a large-scale development proposed on the cliff top in Watchet, planners turn to the adjacent West Cliff Beach, and the inevitable pressure of coastal erosion.
It is accepted that coastal erosion can have damaging influences on coastal communities, and the use of sea defences, where appropriate, can have a positive impact in reducing this damage.
However, interference through means of hard engineered sea defences needs to be carefully considered, including the impacts on sensitive and finite geological features along the foreshore. Geological features found within rocks of the Triassic Period directly below the Cleeve Hill site in the cliffs and foreshore are unique to this section of coast. Inappropriate coastal management can have irreversible and damaging effects to the geology and SSSI as a whole.
Hard Sea Defences
Proposed Unsustainable Coastal Management
In addition to the application for 136 new dwellings on the cliff-top at Cleeve Hill site, a new application has been proposed regarding the development of sea defences on the foreshore below West Cliffs (photo).
This coastal development has the potential to cause irreversible damage to the internationally important geology exposed in the cliffs and foreshore, in addition to reducing the accessibility of the coastline, and the value of the SSSI for recreational, academic and educational purposes.
The following slides visualise the potential coastal management methods that could be employed along the Watchet coast.
West Cliffs: The Current Condition
West Cliffs are currently fully exposed, with access in the east from Watchet. The Upper Triassic - Lower Jurassic geology is readily accessible for study both in the cliff sections and in the foreshore.
A mixture of 'Hold The Line' and 'No Active Intervention' Shoreline Management Planes are currently employed within this section of coastline.
Stone Revetment & Soil Backfill
Boulders of Carboniferous Limestone and Cornish armourstone are a common sight along the Somerset coast, with instalments in Helwell Bay and Watchet Harbour. Recent developments in Blue Anchor have seen 1,800 tonnes of armour stone emplaced against the cliffs to combat coastal erosion.
The proposed installation of a stone revetment, backed by soil/hardcore infill will obscure and irreversibly damage the geological exposures along this stretch of coast.
Photo: Current boulder revetment installed in Helwell Bay, Watchet (2021).
'Offshore' revetment
'Offshore' boulder islands or revetments reduce wave activity and associated cliff erosion; however they have the potential to significantly obscure geological features on the foreshore, in addition to influencing erosion and sedimentation further along the coast.
Similar structures can be seen today in Sidmouth, Devon (below) where the Sidmouth and East Beach Management Plan is developing sea defences to protect Sidmouth and its crumbling cliffs within the Dorset and Devon Coast UNESCO World Heritage Site .
Photo: 'Offshore' boulder islands in Sidmouth, Devon.
Concrete Groynes
Concrete groynes, similar to those already installed in Helwell Bay, Watchet (below), decrease wave energy and reduce sediment transport/erosion along the coastline (longshore drift).
Installation of groynes is less damaging to the cliffs, however can obscure the foreshore geological exposures in addition to influencing sediment transport, build-up and erosion both in the immediate area and further along the coastline.
Photo: Concrete groynes located in Helwell Bay, Watchet (2021).
Wooden Groynes
An alternative visualisation of a groyne installation. Wooden groynes are a common feature in South West England, employed primarily to reduce soft sediment erosion and longshore drift.
Examples of current wooden groynes can be seen in Dunster less than 8km from Watchet (below). These wooden groynes extend up to 35m from the cliffs.
Photo: Wooden groynes located at Dunster Beach, Somerset.
West Cliffs: An Uncertain Future
Coastal erosion is an ongoing and inevitable force on the Somerset coast; landslips and rock falls on the Watchet coast are a common occurrence, and the pressure on local infrastructure , such as the B3191 road, is clear.
Cliff top recession, caused by coastal erosion (image below), illustrates how within the next 30 years much of the B3191 and cliff top dwellings within Watchet itself could be lost to the sea.
Coastal management plans including sea defences, if deemed necessary, should carefully consider all possible impacts on the environment. This includes the risk of coastal development on protected sites such as the Blue Anchor to Lilstock Coast SSSI where sensitive geological interests could be irreversibly lost.
Recent Cliff Subsidence
Further evidence of cliff instability around the Cleeve Hill Site has emerged in April 2022.
Signage warning of the risks of unstable cliffs and rock falls (2022)
Subsidence of a section of the cliff top on West Street was reported to Watchet Town Council in April 2022. Geckoella subsequently undertook an urgent site investigation on behalf of WTC, including drone photogrammetry of the area.
The images below illustrate the scale of subsidence, with the blue line delineating the main scarp plane separating the slumped blocks and the new cliff top. This subsidence has caused the loss of four allotments.
Geckoella's geologists continue to monitor the condition and subsidence of the cliffs in this area using drones, to provide Watchet Town Council with accurate and reliable data to help inform management decisions within and around the site.
Hint: Use the slider to swipe between the annotated image (left) and the aerial image (right).
Cliff subsidence: an orthophoto of the cliff top near West Street, Watchet.
