Belhaven Bay, Dunbar
COASTAL CASE STUDY
Description
Belhaven Bay is located within John Muir Country Park to the west of Dunbar in East Lothian, south-east Scotland, approximately 30 miles east of Edinburgh. The wide bay (2 km) forms in the mouth of the River Tyne, a small river catchment that drains north-eastwards from its source in the Moorfoot Hills near Tynehead. The bay includes a range of coastal landforms, including extensive intertidal sand flats, sand spits, sand dunes, salt marshes and shore platforms. Low coastal cliffs also include evidence for a raised Holocene shoreline and sand beds interpreted to be the product of the Storegga Slide tsunami (around 8150 years ago).
Value to the nation:
- Walking: the eastern section of the John Muir Way coastal path starts from the harbour.
- Tourist area: views to the open sea, with the open water being extremely popular for surfing.
- Historical: there is an interpretation centre celebrating the life of John Muir and a town house museum.
Location
The nearest town is Dunbar and the nearest village, which is within walking distance, is West Barns. The nearest main road is the A1, just over a mile away.
Development of the Spit system
A complex systems of sand spits occur within Belhaven Bay. An inner sand spit — Sandy Hirst spit — occurs within the mouth of the River Tyne, extending about 1 km south-eastwards across the intertidal shore platform. The spit first appeared on Ordnance Survey maps in 1853 and is fed by powerful wave circulation patterns that transfer sediment along the spit. The spit is densely vegetated, which helps to stabilise the dunes (although the undermining of trees demonstrates that material is frequently lost from the tip of the spit) and a steepened eastern neck. It is also likely that the neck of the spit is regularly breached during spring tides and storms.
The outer spit at Belhaven Bay extends north-westwards from Belhaven for approximately 2 km. Formation of this spit was initiated in 1946, with sediment initially derived from a large sand bank. Subsequently, the spit has been fed by the north-westwards longshore transfer of sediment along the coastline.
Geology and the coastline
The bedrock geology present is the Ballagan Formation, which comprises sandstone, siltstone and dolomitic limestone. Much of this is overlain by marine beach deposits of gravel, sand and silt. The area is dominated by softer sedimentary rocks covered in beach sand. The flat-lying layers are younger than the sandstone present to the east and date from the Carboniferous Period, formed on coastal plains and lagoons. To the east of the bay is volcanic rock consisting of Parade Vent tuff and agglomerate overlain mainly by till and raised beach deposits. The area is a section of coast with a wave-cut platform. The high-tide level comes to the base of the cliffs, where they are still being eroded. There are several ravines cut into the volcanic rocks. To the north, salt marsh fills the area between Sandy Hirst and Fir Links Wood and this appears to be gradually accreting.
The Biel Water enters Belhaven Bay between a rocky foreshore and the sweep of the intertidal Belhaven Sands.
Image - oblique aerial view of Biel Water estuary, Belhaven and West Barns, looking from the north-north-east.
P001301 Photo BGS © UKRI
GeoCoast data
Coast type
A simple four-fold classification that identifies the spatial situation for each grid cell. Each cell identifies a lithology and its coastal setting.
Foreshore and backshore data, onshore (beyond the backshore but within the forecast inundation zone) and offshore (area below low-water line) coverage.
Cliff height
Estimated cliff height in metres, determined from digital terrain model (DTM) analysis. Measured from the high-water line to cliff top.
Height in metres from 0 - >100 m.
Cliff erosion
The worst-case erosion susceptibility classification of the cliff or backshore deposits. Click on a cell in the map for more information.
Cliff erosion, worst class scenario.
The mean erosion susceptibility classification of the cliff or backshore deposits. Click on a cell in the map for more information.
Cliff erosion, mean class scenario.
The base lithology (lith1) erosion susceptibility classification of the cliff. This is the first lithology above the high-water line that will be predominantly subjected to wave processes.
Cliff erosion, base lithology (lith1) erosion susceptibility classification of the cliff.
Inundation
Maximum sea-level inundation extents as defined by UK Climate Projections — UKCP18 sea level rise climate scenarios for future sea level rise.
Maximum sea-level inundation extents.
Subcoast potential subsidence rate (PSR)
The potential subsidence for an area considering the combined effects of the geological factors at that location. Provided as % and mm/yr.
Potential subsidence rate in mm/year.
Area statistics
A range of regional statistics have been generated from the baseline datasets to provide an authority-level overview of coastal properties, cliff erosion and flood susceptibility. These are all provided under the Open Government Licence .
- Coastline cliff erosion: the erosion susceptibility classification based on the geological properties showing the worst and mean scenarios for the coastline
- Multi-formations: length of coastline that is made up of cliffs with multiple different geology layers
- Inundation: maximum sea-level inundation extents as defined by UK Climate Projections , UKCP18 sea-level rise climate scenarios for future sea-level rise
These are available in the BGS Onshore GeoIndex .
Coastline management
The East Lothian Shoreline Management Plan indicates a ‘no active intervention policy’ for Belhaven Bay. It is assumed that the spits will be self-sustaining.
Image - the belt of saltmarsh and the new dunes are clearly visible, with the trees at Tyninghame across the Tyne Estuary in the distance, and Bass Rock even further away.
View north from nearby car park at John Muir Country Park cc-by-sa/2.0 - © Mike Pennington - geograph.org.uk/p/1231069
A range of regional statistics has been generated from the baseline datasets to provide Local Plan Districts (Scotland) level overviews of coastal properties, cliff erosion and flood susceptibility. These are all provided under the Open Government Licence .
- Coastline cliff erosion: the erosion susceptibility classification based on the geological properties showing the worst and mean scenarios for the coastline
- Multi formations: length of coastline that is made up of cliffs with multiple different geology layers
- Inundation: maximum sea-level inundation extents as defined by UK Climate Projections , UKCP18 sea level rise climate scenarios for future sea level rise
These are available in the BGS Onshore GeoIndex .
Aerial photographs
Comparison of aerial photos of Belhaven Bay over an 11-year period. Left: 2009: Right: 2020. Google Earth © 2020 Infoterra Ltd & Bluesky. Image NASA
Onshore and offshore data from BGS
Onshore and offshore agencies and media
Gallery
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