Isles of Scilly PDZ18
General actions for this subsection
There are no actions generic to the whole of this subsection. For actions relating to specific locations, select an area on the map above or use the postcode/location search and click on the Action Plan tab.
All actions are subject to funding and approval, often by other parties than the Lead Organisation shown.
Download SMP documents
The information on this website represents the current SMP management approaches adopted by the local authorities within its area, and current actions needed to deliver them. These management approaches have been approved by the Environment Agency under its Strategic Overview for coastal flood and erosion risk management and are considered to be local policy.
The documents below provide the full SMP adopted locally and approved by the Environment Agency at the time of publication. Some of the information has changed in response to new government policy, new evidence or new work identified.
Data on this page
Main report
- Chapter 1 - Introduction
- Chapter 2 - Environmental Assessment
- Chapter 3 - Basis for the Plan
Chapter 4 - Management Units:
- Introduction to the management units
- PDZ1 - Pencarrow Head to Gribbin Head - Introduction
- MA1 - Rame Head to Downderry
- MA2 - Downderry and Seaton
- MA3 - Seaton to Pencarrow Head
- PDZ2 - Pencarrow Head to Gribbin Head - Introduction
- MA4 - Pencarrow Head to Gribbin Head
- MA5 - Fowey Estuary (above Mixtow) inc tributaries
- PDZ3 - Gribbin Head to Black Head - Introduction
- MA6 - Gribbin Head to Par Docks
- MA7 - Par Docks to Black Head
- PDZ4 - Black Head to Zone Point - Introduction
- MA8 - Black Head to Dodman Point
- MA9 - Veryan Bay
- MA10 - Gerrans Bay
- PDZ5 - Zone Point to Nare Point - Introduction
- MA11 - Lower Fal
- MA12 - Upper Fal
- MA13 - Pendennis Point to Rosemullion Head
- MA14 - Helford
- PDZ6 - Lizard (Nare Point to Baulk Head - Gunwalloe) - Introduction
- MA15 - Lizard East (Nare Point to Lizard Point)
- MA16 - Lizard West (Lizard Point to Baulk Head)
- PDZ7 - Mounts Bay East (Baulk Head (Gunwalloe) to Marazion) - Introduction
- MA17 - Baulk Head to Trewavas Head
- MA18 - Trewavas Head to The Greeb
- PDZ8 - Mounts Bay West (The Greeb to Point Spaniard (Inc Marazion and St Michael’s Mount - Introduction
- MA19 - Marazion to Longrock
- MA20 - Longrock to Penzance
- MA21 - Penzance and Newlyn (Albert Pier to Sandy Cove)
- MA22 - Mousehole (Sandy Cove breakwater - Point Spaniard)
- PDZ9 - Penwith Peninsula (Point Spaniard to Clodgy Point) - Introduction
- MA23 - Point Spaniard to Land’s End
- MA24 - Land’s End to Clodgy Point (St Ives)
- PDZ10 - Clodgy Point to Godrevy Point - Introduction
- MA25 - Clodgy Point to Porthminster Point
- MA26 - Porthminster Point to Hayle Estuary
- MA27 - Hayle Estuary
- MA28 - Black Cliff to Godrevy Point
- PDZ11 - North Cliffs (Godrevy Point - Pentire Point West) Introduction
- MA29 - Godrevy Point to St Agnes Head
- MA30 - St Agnes Head to Pentire Point West
- PDZ12 - Newquay (Pentire Point West - Trevelgue Head) Introduction
- MA31 - Fistral Bay and Crantock
- MA32 - Newquay Bay
- PDZ13 - Trevelgue Head to Stepper Point - Introduction
- MA33 - Trevelgue Head to Trevose Head
- MA34 - Trevose Head to Stepper Point
- PDZ14 - Camel Estuary (Stepper Point to Pentire Point) - Introduction
- MA35 - Camel Estuary (Stepper Point to Trebetherick Point)
- MA36 - Trebetherick Point to Pentire Point
- PDZ15 - Pentire Point to Wanson Mouth - Introduction
- MA37 - Pentire Point to Boscastle
- MA38 - Boscastle to Wanson Mouth
- PDZ16 - Widemouth & Bude (Wanson Mouth to Lower Sharpnose Point) - Introduction
- MA39 - Wanson Mouth to Higher Longbeak
- MA40 - Higher Longbeak to Lower Sharpnose Point
- PDZ17 - Lower Sharpnose Point to Hartland Point - Introduction
- MA41 - Lower Sharpnose Point to Hartland Point
- PDZ18 - Isles of Scilly - Introduction
- MA42 - St Mary’s
- MA43 - St Martin’s
- MA44 - Tresco
- MA45 - Bryher
- MA46 - St Agnes and Gugh
Chapter 5 – Summary of Preferred Plan Introduction:
- Chapter 6 - Action plan
- Glossary
- Acknowledgements
Appendices
- Appendix A – SMP Development
- Appendix B – Stakeholder Engagement
- Appendix C - Baseline
- Appendix D – Theme Review Final Report
- Appendix E – Issues and Objectives
Appendix F - SEA:
- Appendix G – Scenario Testing
Appendix H - Economic Appraisal:
Appendix I - HRA:
- Appendix A Cornwall And Ios Smp2 Appropriate Assessment 1
- Appendix B Sssi Condition Tables
- Appendix D Hr01
- Appendix E Hr02
- Hra Appendix C1 Pdz10 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz11 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz12 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz13 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz14 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz16 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz18 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz1 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz2 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz3 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz4 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz5 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz6 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz7 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz8 Assessment Tablesv2 Submitted
- Hra Appendix C1 Pdz9 Assessment Tablesv2 Submitted
- Appendix J - Water framework Assessment
- Appendix K - GIS Data
- Appendix L - Adoption
About this subsection
This sub-section covers the Isles of Scilly. These are an archipelago of around 140 islands that emerge from the Atlantic around 45km west of Land’s End, formed from the remnants of an upstanding granite landform linked to Cornwall. Of the 140 islands, the five main inhabited islands are considered within the SMP. These islands are St Mary’s, Tresco, Bryher, St Martin’s and St Agnes. The sub-section is split into 62 smaller local shoreline management units.
The very location of Scilly makes it a unique place to live or to visit. All the islands display an extremely strong sense of community and this cohesion and sense of identity is a key asset.
The archipelago combines areas of wild, exposed coastline, open to the full energy of the Atlantic, with extremely sheltered nearshore areas of white sand and shallow blue seas. The entire archipelago is owned by the Duchy of Cornwall although there are residential parts of St Mary’s which are held by private landowners and the Island of Tresco is wholly leased to another organisation.
The largest inhabited island is St Mary’s, which is home to the main settlement of the islands, Hugh Town. Hugh Town is built for the most part on a sandy iszmuth, which connects the two granite islands that form St Mary’s. St Martins is the most northerly of the populated Isles of Scilly and lies 2.5km NNE of St Mary’s. It is surrounded by numerous smaller uninhabited islands and islets, particularly on its western and southern flanks.
Tresco and Bryher lie close to one another to the north-west of St Mary’s. Numerous uninhabited islands and islets, including one of the large uninhabited islands, Samson, which is renowned for its archaeological interest, surround them. Bryher is more exposed than Tresco and its sheltered eastern shoreline has extensive sandy areas. The island of Tresco is to an extent managed separately from the other islands, under a long-term lease from the Duchy.
The most southerly of the inhabited Isles is St Agnes. Immediately to the east lies Gugh, a smaller island that is considered along with St Agnes as they are linked by coastal processes.
Coastal processes are complex across the archipelago, with different islands exposed to different angles of wave attack, which can be extreme, but equally some areas are very sheltered. The complex archipelagic geometry and the resulting numerous channels between islands creates a myriad of tidal flows and strong currents under certain tidal conditions.
The more sheltered inner coastal areas are dominated by fine sandy sediments and some sediment exchange between frontages would be anticipated. Whilst the fact that the entire archipelago is formed from an enormous granite batholith means the bedrock geology is resistant to erosion, there are significant overlying superficial periglacial slope deposits (locally known as ‘ram’) which are highly erodible. The granite and ram in Scillonian coastal cliffs are both competent enough to stand up at least vertically and in some cases beyond vertical (overhangs), particularly where horizontal layers exist in the granite. The main process of mass movement is therefore falls, where wave undercutting and/or high pore water pressure overcome the resistance of the slope mass to failure, or weathering leads to slope failure. Toe regolith is usually removed quickly by the sea, so masking of the toe is rare, although granite boulder regolith toes do exist where granite cliffs are particularly tall.
This erosion puts a significant amount of the island’s existing development at risk in the longer term. Flood risk driven by wave overtopping is already pronounced during severe storm events, and the defended areas of Scilly will become increasingly vulnerable to flooding as sea level rise accelerates.
The risk profile across the five main islands is therefore also complex. A key problem for Scilly is that it has limited physical space to accommodate adaptation, and its main settlement sits in one of the lowest lying areas. In addition, the risk to potable water supplies from saline intrusion is already high and will also increase in line with sea level rise. Climate change impacts and sea level rise therefore represent something of an existential challenge for Scilly, at least in terms of the form currently taken by its built environment and how its populated areas function.
The historic environment is of great importance to Scilly with scores of Scheduled Monuments (238 in total), reflecting centuries of inhabitation upon the Islands. This is the highest density of designation within any local authority area within the UK. Large areas of the five inhabited islands are also scheduled for their nationally important archaeology, much of which lies within coastal or intertidal locations. The entire archipelago and its ecology is also designated for its international importance.
Key drivers for management therefore include the hugely significant value of tourism to Scilly’s economy; the historical, archaeological, geological and ecological significance and importance; fundamental and far-reaching impacts of sea level rise and erosional processes; connectivity to the mainland for essential services and for tourism; the identity of communities and the different Island’s; potable water resources and impacts from sea level rise (particularly for St Agnes).
The high-level objective for Scilly must be based upon providing a framework of management which will support the adaptation of all island communities to coastal change and developing their resilience. However, the techniques employed in doing so must be sensitive to the wider aspirations of bodies such as Natural England and the Wildlife Trust in managing the archipelago much as a fragile Marine Park eco-system.