Cell 11 Regional Monitoring Strategy (CERMS) 2010 Monitoring Update Report

Cell 11 Regional Monitoring Strategy (CERMS)

2010 Monitoring Update Report

Contents Amendment Record This report has been issued and amended as follows:

Issue Revision Description Date Approved by

2010 update to CERMS baseline report. Updated by Lily Booth. Comments and 1 1 28.2.12 Nigel Pontee further updates from Alan Wiliams and Ken Pye.

2010 update to Cerms baseline report. 1 1.1 Updated by P.Wisse, Smbc following 31.10.12 comments in first draft

Halcrow Group Limited

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Tel +44 (0)1793 812479 Fax +44 (0)1793 812089 www.halcrow.com

Halcrow Group Limited has prepared this report in accordance with the instructions of their client, Sefton Council, for their sole and specific use. Any other persons who use any information contained herein do so at their own risk.

Metadata

Addressee Aggregation Audience Coastal/Environmental Engineers Contributor(s) Coverage Cell 11: Great Orme’s Head to the Scottish Border (including sub-cells 11a, b, c, d and e) Creator Halcrow Group Ltd Date Description Cell 11 Regional Monitoring Strategy (CERMS) 2010 Monitoring Update Report Format Text Identifier Language English Location Mandate CERMS Regional Monitoring Framework Publisher Sefton Council Relation Status Draft Subject Coastal Processes Title CERMS 2010 Monitoring Update Report Type Text/report

Table of Contents

LIST OF TABLES ...... II LIST OF FIGURES ...... III EXECUTIVE SUMMARY ...... 1 1 INTRODUCTION ...... 2

1.1 CERMS OBJECTIVES 2 1.2 THE ROLE OF THIS REPORT 2 1.3 RELATED STUDIES 3 2 DATA AVAILABILITY ...... 5

2.1 INTRODUCTION 5 2.2 LOCAL FRAMEWORK DATA 5 2.3 CERMS STRATEGIC MONITORING 7 2.4 SUMMARY OF DATA HELD IN EXISTING SANDS DATABASE 8 2.5 OTHER LOCAL DATA COLLECTED BUT NOT CURRENTLY RECORDED IN SANDS 24 2.6 OTHER MONITORING PROGRAMMES 25 2.7 DATA / INFORMATION AVAILABLE FROM LINKED STUDIES 27 2.8 OTHER THIRD PARTY DATA SOURCES 33 3 CELL WIDE BASELINE ...... 34

3.1 INTRODUCTION 34 3.2 EXISTING UNDERSTANDING 34 3.3 ISSUES AND UNCERTAINTIES 56 4 SUB-CELL BASELINES ...... 62

4.1 INTRODUCTION 62 4.2 SUB CELL 11A 63 4.3 SUB-CELL 11B 88 4.4 SUB CELL 11 C 105 4.5 SUB CELL 11 D 131 4.6 SUB CELL 11 E 146 5 OPERATIONAL MATTERS ...... 164

5.1 DATA COLLATION AND MANAGEMENT 164 CONCLUSIONS FROM CERMS REVIEW 165 6 CONCLUSION ...... 167 7 RECOMMENDATIONS ...... 171 8 REFERENCES ...... 188

APPENDIX A

List of Tables

Table 2.1 Sub-cell 11a fixed monitoring instruments…………………………………………... 10 Table 2.2 Sub-cell 11b fixed monitoring instruments…………………………………………... 15 Table 2.3 Sub-cell 11c fixed monitoring instruments…………………………………………... 18 Table 2.4 Sub-cell 11e fixed monitoring instruments…………………………………………... 22 Table 3.1 Uncertainties in present regional understanding…………………………………….. 40 Table 3.2 Recommendations for CERMS arising from CETaSS Study 43 Table 4.1 Extreme Sea Levels for North Wales (Atkins (2008) North Wales Tidal Flood Mapping Phase II Report)……………………………………………………………. 63 Table 4.2 Extreme Sea Levels for Central North West England (JBA Consulting (2007), Central Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... 64 Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding...... 68 Table 4.4 Extreme Sea Levels for Central North West England (JBA Consulting (2007), Central Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... 90 Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding...... 93 Table 4.6 Extreme Sea Levels for Central North West England (JBA Consulting (2007), Central Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... 109 Table 4.7 Extreme Sea Levels for North Area, North West England (JBA Consulting (2007), North Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding...... 113 Table 4.9 Extreme Sea Levels for North Area, North West England (JBA Consulting (2007), North Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... 137 Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding...... 140 Table 4.11 Extreme Sea Levels for North Area, North West England (JBA Consulting (2007), North Area Tidal Areas Benefiting from Defence. Final Sea Level Report)...... 153 Table 4.12 Sub-Cell 11e - Supporting information for Conceptual Understanding...... 154

List of Figures

Figure 2.1 Overview of data currently held in SANDS, database Sub-cell 11a………………... 14 Figure 2.2 Overview of data currently held in SANDS, database Sub-cell 11b……………….... 16 Figure 2.3 Overview of data currently held in SANDS, database Sub-cell 11c ……………….. 19 Figure 2.4 Overview of data currently held in SANDS, database Sub-cell 11d………………... 21 Figure 2.5 Overview of data currently held in SANDS, database Sub-cell 11e………………… 23 Figure 3.1 Overview of Cell 11 study area, showing SMP2 sub-cell frontages………………… 31 Figure 3.2 Bathymetry used in Halcrow’s Irish Sea Regional Model………….. 32 Figure 3.3 Wind rose offshore from Barrow………………………………………...……….... 33 Figure 3.4 Peak depth averaged flood currents in Cell 11………………………………….... 35 Figure 3.5 Peak depth averaged ebb currents in Cell 11……………………………………….. 36 Figure 3.6 Residual (monthly average tidal currents)……………………………………….... 38 Figure 3.7 Wave roses for the Cell 11 coastline (adapted from Halcrow 2002)……………. 42 Figure 3.8 Distribution of sea-bed sediments. Classification after Folk (1954). Modified from Jackson et. al., (1995)……………………………………………………………… 44 Figure 3.9 Mean sea bed bottom stress. After Pingree and Griffiths (1979)…………………... 45 Figure 3.10 Preliminary schematic representation of the principal marine and fluvial sediment transport pathways in the eastern Irish Sea (Pye and Blott, 2009)…………………. 46 Figure 4.1 Location map of sub-cell 11a…………………………………………………….... 61 Figure 4.2 Sub-cell 11a Conceptual Understanding…………………………………………….. 67 Figure 4.3 Location map of sub-cell 11b………………………………………………………... 88 Figure 4.4 Sub-cell 11b Conceptual Understanding………………………………………….. 92 Figure 4.5 Location map of sub-cell 11c…………………………………………………….... 106 Figure 4.6 Sub-cell 11c Conceptual Understanding…………………………………………….. 112 Figure 4.7 Location map for sub-cell 11d…………………………………………………….. 135 Figure 4.8 Sub-cell 11d Conceptual Understanding………………………………………….. 139 Figure 4.9 Location map for sub-cell 11e…………………………………………………………... 151 Figure 4.10 Sub-cell 11e Conceptual Understanding…………………………………………… 156

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Glossary Term Definition Accretion In geography, accretion means the land increasing due to sediment being added to it. Dune system Dunes are subject to dune processes, i.e. accretion (via the onshore transport of sand), and erosion, which maintain the same structure and habitat. Aeolian transport Sediment transport by wind Alluvial deposits loose, unconsolidated (not cemented together into a solid rock), soil or sediments, eroded, deposited, and reshaped by water in some form in a non- marine setting Anthropogenic General term used to describe the influence of man e.g. the influence of sea influences/modification defences or management actions on coastal processes. Barometric pressure Atmospheric pressure. Barrier The function of a barrier is to control the water level. It consists of a combination of a concrete or a steel structure with or without adjacent rockfill dams. Bathymetry The measurement of depths of water in oceans, seas and lakes; also the information derived from such measurements. Beach A deposit of non-cohesive material (e.g. sand, gravel) situated on the interface between dry land and the sea (or other large expanse of water) and actively "worked" by present-day hydrodynamic processes (i.e. waves, tides and currents) and sometimes by winds Beach profile A cross-section taken perpendicular to a given beach contour; the profile may include the face of a dune or seawall, extend over the backshore, across the foreshore, and seaward underwater into the nearshore zone. Beach Recharge This is the management practice of adding to the natural amount of sediment (such as sand) on a beach by using material from elsewhere. This is also known as beach replenishment, nourishment or feeding. Breaker height The wave height at the point a wave breaks Breakwater A structure projecting into the sea that shelters vessels from waves and currents, prevents siltation of navigation channel, protects a shore area or prevents thermal mixing (e.g. cooling water intakes). In beach management, breakwaters are generally structures protecting areas from the full impact of breaking waves. Breakwaters may be shore-attached and extended seawards from the beach, or may be detached and sited offshore, generally parallel to the beach to provide sheltered conditions. Cell 11 Regional Regional Monitoring Strategy for the area known as Cell 11 from Llandudno to Monitoring Strategy Solway Firth (CERMS) Chart Datum (CD) Approximately the lowest astronomical tidal level, excluding the influence of the weather. Clay A fine-grained, plastic, sediment with a typical grain size less than 0.004mm. Possesses electro-magnetic properties which bind the grains together to give a bulk strength or cohesion. Cliffing The development of almost vertical cliffs, up to 2m high (although generally less than 1m) following creation of a new beach slope after beach recharge. The cliffs occur at, or above mean high tide, and are a result of mixing of different sized sediments and compaction of material by mechanical plant. Climate change Long term changes in climate, specifically linked to human activity. For example, the release of greenhouse gases to the atmosphere from burning fossil fuels; the results of which may lead to increased rainfall, tide levels, etc. Coastal Processes Collective term covering the action of natural forces on the shoreline, and nearshore seabed.

Coastal squeeze The process by which coastal habitats and natural features are progressively lost or drowned, caught between coastal defences and rising sea levels Current Flow of water.

Term Definition Cusp/cuspate Seaward bulge, approximately parabolic in shape, in the beach contours. May occur singly, in the lee of an offshore bulk or island, or as one of a number of similar, approximately regularly-spaced features on a long straight beach Defra Department for Food, Environment and Rural Affairs. The Government Department responsible for setting out what the SMP2 should do and look like. Delta Deltas are prograding wedges of sediment at a river's mouth Diurnal Tide A tide in which there is only one high water and one low water each lunar day Downdrift Longshore drift is the movement of beach materials along the shore, if a location is described as downdrift, it is located further down the sediment pathway than an alternative area. Dredging An excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. Dune Accumulations of windblown sand on the backshore, usually in the form of small hills or ridges, stabilised by vegetation or control structures Ebb-tide The falling tide. Part of the tidal cycle between high water and the next low water. Embankment An artificial bank raised above the immediately-surrounding land to redirect or prevent flooding by a river, lake or sea Environment Agency A non-departmental government body responsible for looking after the environment in England and Wales including flood defence, water resources, water quality, pollution control. Erosion The loss of land due to the effects of waves and, in the case of coastal cliffs, slope processes (such as high groundwater levels). This may include cliff instability, where coastal processes result in landslides or rock falls. Estuary Mouth of a river, where fresh river water mixes with seawater. Fetch Distance over which a wind acts to produce waves - also termed fetch length. Flood and coastal Flood Risk Management addresses the scientific and engineering issues of erosion risk rainfall, runoff, rivers and flood inundation, and coastal erosion, as well as the management human and socio-economic issues of planning, development and management. Flood – tide Period of the tide progressing from low water to high water Foreshore The intertidal area below highest tide level and above lowest tide level. Fluvial Belonging to rivers streams or ponds. e.g. Fluvial flooding, fluvial plants Foreshore The area between the high water and low water marks. Geomorphology/ The make up of the earth’s surface including the distribution of the land, water, Morphology etc. Glacier a perennial mass of ice which moves over land Gravel .Sediment particles larger than 2 mm but smaller than 63 mm) Groyne A structure built into the sea from the shore which traps material moved around by the sea. Headland Hard feature (natural or artificial) forming local limit of longshore extent of a beach Hinterland The area landward of flood or coastal defences. Hydrodynamics The study of liquids in motion. Hydrographic Survey The science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore oil exploration/drilling and related disciplines Infrastructure The basic facilities and equipment for the functioning of the country or area, such as roads, rail lines, pipelines and power lines. Inshore Areas where waves are transformed by interaction with the sea bed Intertidal zone The area of the seabed exposed between the highest and lowest levels of the tide.

Isobath A contour line on a map connecting points of equal depth in a body of water Isostatic rebound The rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostasy.

Term Definition Jetty Any of a variety of structures used in river, dock, and maritime works which are generally carried out in pairs from river banks, or in continuation of river channels at their outlets into deep water; or out into docks, and outside their entrances; or for forming basins along the sea-coast for ports in tideless seas. Joint probability The probability of two (or more) things occurring together Land reclamation Creating new, dry land on areas that have previously been seabed. Littoral Of or pertaining to the shore Littoral drift, Littoral The movement of beach material in the littoral zone by waves and currents. transport Includes movement parallel (longshore drift) and perpendicular (cross-shore transport) to the shore Littoral zone Zone from the beach head seawards to the limit of wave-induced sediment movement. Local Development A plan system to manage how development takes place in towns and the Frameworks countryside. It is a folder of local development documents prepared by district councils, unitary authorities or national park authorities that outline the spatial planning strategy for the local area. Longshore current A movement of water along the shore, caused by waves and tides. Longshore transport Movement of material along the shore. Sometimes called longshore drift or alongshore drift. M2 Principal lunar semidiurnal constituent M4 Shallow water over-tides of principal lunar constituent Macrotidal Areas where the tidal range is in excess of 4 m. Tidal currents dominate the processes active in macrotidal areas. Managed realignment Allowing the existing sea defence line to move further inland (naturally or in a controlled way) to reduce flood risk. Material assets Properties, equipment or items to which a value can be assigned Mean sea level Average height of the sea surface over a 19-year period. Mean High Water The average of all high waters recorded over a long period. (MHW) Mean High Water The average height of the high waters of spring tides recorded over a long Springs (MHWS) period. Mean Low Water The average of all low waters recorded over a long period. (MLW) Mean Low Water The average height of the low waters of spring tides recorded over a long Springs (MLWS) period. Mudflats A coastal wetlands that form when mud is deposited by tides or rivers. Multibeam technology The use of echo sounders which can be used for a range of coastal monitoring and mapping applications, including geological and oceanographic research. Nearshore The zone which extends from the swash zone to the position marking the start of the offshore zone, typically to water depths of the order of 20m. Ordnance Datum (OD) The universal zero point used in the UK (equal to the mean sea level at Newlyn in Cornwall) from which the height of the land is measured. Overtopping Water carried over the top of a coastal defence due to wave run-up exceeding the crest height Pebble Beach material usually well-rounded and between about 4mm and 75mm in diameter Policy In this context, “policy” refers to the generic shoreline management options (No Active Intervention, Hold the Existing Line of Defence, Managed Realignment and Advance the Existing Line of Defence). Policy Scenario Brings together individual policy units that interact with those next to them (i.e. a group of policy units which share the same SMP2 policy option). Policy Statement A statement declaring and describing the proposed management policy to be adopted in a particular time period. Policy Unit Sections of coastline for which a certain coastal defence management policy has been defined. Pollution A pollution incident is any discharge to land, air or water that could cause environmental damage

Term Definition Primary defence The main line of defence, usually the most seaward if several defence structures are present. Recharge The process of replenishing a beach by artificial means; e.g., by the deposition of dredged materials, also called beach renourishment or beach feeding. Revetment A coastal defence made with stones laid on a bank sloping upwards from the beach Ridge A geological feature which has a continuous elevational crest for some distance Risk Any uncertainty which should it occur, will affect the delivery of the project objectives. Roll-back The process whereby coastal habitats move landward due to rising sea levels. Saltmarsh Intertidal area having characteristic vegetation adapted to saline soils and to periodic submergence in sea water Sand Sediment particles., with a diameter of between 0.0.063mm and 2mm, generally classified as ‘very fine’, `fine', `medium', `coarse' or `very coarse' Sandflat sandy tidal flat barren of vegetation. SANDS database Coastal information database developed by Halcrow Scour Sand and sediment being removed by waves or currents, especially at the base and ends of coastal defence structures. Sea defences Works to alleviate flooding by the sea, sometimes known as flood defences Sea level rise The rise of the height of the sea in relation to the land. This can be caused by global climate change and changes in local land levels. Seawall Solid coastal defence structure built parallel to the coastline Sediment Particulate matter derived from rock, minerals or bioclastic debris Sediment flux The inputs and outputs of sediment to a given location. Sediment sink Point or area at which beach material is irretrievably lost from a coastal cell, such as an estuary, or a deep channel in the seabed Sediment source Point or area on a coast from which beach material arises, such as an eroding cliff, or river mouth Sediment transport The movement of sedimentary material. The main agents of sediment transport are gravity, running water (rivers and streams), ice (glaciers), wind and sea (currents and waves). Semi-diurnal Tide with two high waters and two low waters each lunar Shingle A loose term for coarse beach material, a mixture of gravel, pebbles and larger material, often well-rounded and of hard rock, e.g. chert, flint, etc. Shoreline The specific point at which the sea meets the land. This can vary depending on when the shoreline is measured, e.g. high water shoreline. Shoreline Management A plan which assesses the coast and provides evidence to Local Authorities and Plan (SMP) other organisations to help them reduce risk of erosion and flooding to people and the developed, historic and natural environment in a sustainable way. The original SMPs were developed in the late 1990s. Silt Sediment particles .in the size range 0.0.002mm to 0.062mm, i.e. coarser than clay particles but finer than sand Spit A build up of sand or gravel where a shoreline changes direction. These are formed by waves moving sand or gravel along the shoreline to form a promontory jutting out from the coast. Spatial scales A ‘shorthand’ term for relative lengths, areas, distances and sizes Stakeholder A person or organisation with an interest in the preparation of, and outcomes from, the shoreline management plan. Stakeholders can include agencies, authorities, organisations, individuals and private bodies. Strategy Studies A long term plan, known as a flood defence management strategy, which sets out ways to manage. These look at a broad range of local interests and issues. Still water level Average water surface elevation at any instant, excluding local variation due to waves and wave set-up, but including the effects of tides, surges and long period seiches

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Term Definition Storm event A storm event can be described by several sea-states, e.g. the increasing phase, the maximum phase and the decreasing phase. At locations under tidal influence the typical sea-state is very often only 2–3 hours, but without tidal effects it may last 6 hours or longer depending on the evolution in time of wind conditions (typical time-scale in the order of 12 hours to one day). Surge Changes in water level as a result of meteorological forcing (wind, high or low barometric pressure) causing a difference between the recorded water level and that predicted using harmonic analysis; may be positive or negative. Temporal scales Time scales. Tidal current The direction that the sea moves when influenced by the rise and fall of the tide. Tidal prism The .volume of water in the estuary between the level of high and low tide. Tidal range Vertical difference in high and low water level once decoupled from the water level residuals Tidal wave The rise and fall in water level due to the passage of the tide Tide The rise and fall of the sea caused by the gravitational pull of the moon and sun on the earth. Toe protection Putting boulders or other large materials at the bottom of coastal defences to stop waves from removing the material that the defence sits on. Topography The shape of the earth’s surface including land levels and the position of natural and man-made features. Training walls A wall built to confine or guide the flow of water over the downstream face of an overflow dam or in a channel Transgression The way that the shoreline moves towards the land due to a rise in sea level. Updrift The opposite direction to the movement of beach materials along the shore. Water depth Distance between the seabed and the still water level Waverider Buoy A surface following buoy anchored to the sea bed by means of elastic mooring. Wave direction Mean direction of wave energy propagation relative to true North Wave height The vertical distance between the trough and the following crest Wave period The time taken for two successive wave crests to pass the same point Wave propagation The way in which a wave travels. Wave transformation Change in wave energy due to the action of physical processes. Mean zero crossing The average time interval between similar direction crossings of mean water period. level for a wave record.

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Executive Summary

This report provides an update of the baseline summary for the Cell Eleven Regional Monitoring Strategy (CERMS) based on the monitoring carried out in 2010. The Cell 11 coastal area extends from Great Orme’s Head in North Wales to the Scottish border in the Solway Firth and has been geographically split into 5 sub-cells, 11a to 11e.

CERMS was developed to provide a consistent regional approach for the gathering and management of coastal process data such as waves, wind, tides, sediment transport, beach levels, shoreline change and coastal defence performance. The purpose of this is to provide coastal defence managers with relevant information that will assist in making sustainable shoreline management decisions.

The report presents:

• An overview of current coastal process data availability;

• A regional (Cell 11) conceptual understanding of coastal processes and shoreline management issues;

• More detailed conceptual understanding of sediment transport and shoreline change for each of the five sub-cells using diagrams and summary tables;

• Summary interpretation of recent local monitoring information, where available, and comments on its agreement with the current understanding; and

• A list of specific uncertainties in coastal processes that need to be addressed through future shoreline management data collection, analysis and interpretation. The 2009 Baseline report has been updated using results from local and regional monitoring and modelling activities carried out in 2010. The Conceptual Model from the previous report has been clarified and improved by the addition of the modelling data. The monitoring gives a picture of the ongoing processes and an idea of the variability of these processes through time. The overview of the dominant processes in each sub-cell is presented in the conceptual model diagram for each sub-cell. Future versions of this report will be compared against the baselines described, reducing uncertainty, either by confirming present understanding or allowing changes to be recognised and trends in behaviour established.

1 Introduction

1.1 CERMS Objectives

The Cell Eleven Regional Monitoring Strategy (CERMS) was developed to provide a consistent regional approach to coastal process monitoring, providing information for the development of strategic shoreline management plans, coastal defence strategies and operational management of coastal protection and flood defence. The CERMS programme is co-ordinated by Sefton Council and is managed by a task group on behalf of the North West England and North Wales Coastal Group, which includes representatives from the local maritime authorities, the Environment Agency, Natural England and Lancaster University. The programme is funded by Grant Aid from the Environment Agency. The main objectives of the CERMS strategy are: • To provide a coherent and consistent framework for strategic and local shoreline monitoring data collection, collation and analysis within Cell 11; • To move forward the recommendations made in the first round of SMPs in order to provide a coherent package of monitoring data collection, collation and analysis; • To improve understanding of coastal process behaviour and how those processes interact with the shoreline at a local, sub-regional and regional scale; • To assist in the definition of the magnitude of risks of coastal flooding and erosion and to provide data to support re-evaluation of those risks in the future; and, • To assist coastal managers by providing them with relevant information on which to make sustainable future shoreline management decisions.

1.2 The Role of this Report

This report summarises present conceptual understanding and areas of uncertainty relating to coastal processes and shoreline management issues throughout the Cell 11 region. The report reviews the data being collected throughout the region and suggests how it can be used to improve the understanding of coastal processes and the management of flood and coastal erosion risk. The report is split into 3 main sections:

• Section 2 - Data availability; • Section 3 - Regional cell-wide baseline; and, • Section 4 - Sub-cell baseline. Additionally, section 5 covers the operational matters associated with CERMS, and provides a summary of the review of CERMS project performance carried out in 2009.

The present report is an update of the Baseline Report produced in 2009 with updates for the 2010 monitoring and modelling. To facilitate future comparison against these baselines summary diagrams, maps and tables have been used wherever possible. The report is intended to assist in the analysis, interpretation and planning of future data collection under the CERMS programme by allowing comparison against an accepted summary of coastal processes. This report presents the existing conceptual model for the Cell 11 coastline, which is a work in progress. The conceptual model should

be seen as being a ‘live’ model which can be updated with the most recent knowledge as the monitoring regime progresses.

1.3 Related Studies Two regional studies, CETaSS and JPS, designed to feed into and inform CERMS, have been carried out as linked studies to the North West England and North Wales SMP2:

1.3.1 The Cell Eleven Tidal and Sediment Transport Study The Cell Eleven Tidal and Sediment Transport Study (CETaSS) .was intended to lead to a better understanding of the coastal processes including tidal currents, water levels, waves and sediment transport within the region.

CETaSS had the following objectives:

• To reduce uncertainty relating to coastal processes and specifically tidal currents and sediment transport; and,

• To provide coastal process information and understanding to improve the evidence base for selection of future flood and coastal erosion risk management (FCRM) policies in the Shoreline Management Plan and Strategy studies.

The following studies were undertaken:

• Regional tidal and sediment modelling - including offshore (Halcrow, 2010c) and littoral transport (Halcrow, 2010d);

• Review of offshore banks - including characteristics and processes (Halcrow, 2010e);

• Estuary Morphodynamics - including morphology, processes, past evolution, sediment supply and future behaviours (Halcrow, 2010f and g);

• Local scale modelling of the Ribble (Halcrow, 2010h) and Duddon (Halcrow, 2010i)

• Morecambe Bay studies - including sediment fluxes, sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j) and,.

• Assessment of coastal squeeze - including historical changes and likely future trends (Halcrow, 2010k);

1.3.2 The Cell 11 Wave and Water Level Joint Probability Study The Joint Probability Study (JPS) (Halcrow 2011a) has produced consistent joint probability estimates for waves and water levels around the whole of the Cell 11 coastline to feed into subsequent studies.

JPS had the following objectives:

• To produce a review of available tide and wave information;

• To produce consistent joint probability estimates for waves and water levels for Cell 11; and,

• To provide consistent wave modelling around the Cell 11 shoreline that can be used to provide sufficient wave data to feed into assessments of regional littoral sediment transport budgets (part of the CETaSS study).

1.3.3 North West England and North Wales Shoreline Management Plan2 The North West England and North Wales Shoreline Management Plan2 (http://mycoastline.org/) provides a large-scale assessment of the risks associated with coastal erosion and flooding at the coast, and provides policies to help manage these risks to people and to the developed, historic and natural environment in a sustainable manner. The SMP2 has undertaken a review of coastal processes, defining the current understanding of how the coast functions and its present behaviour. This review of coastal processes for the Cell 11 coast has fed directly into the present report.

1.3.4 Other Sources In addition, the Cell 11 Regional Monitoring Strategy Project Review (Coastal Engineering UK Ltd, 2009) also includes details of a number of other related national and regional studies and commercially based and non-commercially based monitoring programmes. In summary, these comprise:

• The Irish Sea Coastal Observatory provides recorded wave data, bathymetry, wave and current measurements which can be utilised within CERMS;

• National and Local Research Programmes and Initiatives. Such programmes and initiatives, including Environment Agency/Defra joint flood and coastal defence research programme, should inform CERMS at both local and cell wide scales; and,

• External Sourced Studies. External data sourced as part of offshore or shoreline developments could be useful in supplementing data already collected under CERMS.

2 Data Availability

2.1 Introduction

This section summarises the data that are being collected or is available throughout the Cell 11 region and the annual additions to the database. Data are being collected at two levels, locally by the local authorities and regionally by the coordinating authority, Sefton Council. This covers:

• Local Framework Data;

• Data being strategically collected under CERMS;

• Data already currently held within the SANDS database;

• Data / Information available from linked studies;

• Other third party data sources (e.g. Universities); and,

• Linkages between strategic and local data collection.

2.2 Local Framework Data The local frameworks collect data at a local level and are led by the local authority or, where appropriate, groups of local authorities. The following local frameworks have been set up to manage local data collection and analysis:

• North Wales (Conwy CBC, Denbighshire CC and Flintshire CC) – Managed by Conwy CBC;

• Wirral;

• Sefton;

• Blackpool;

• Wyre and Fylde;

• Morecambe Bay (Lancaster CC, South Lakeland DC) – Managed by Lancaster CC;

• Barrow;

• Copeland; and,

• Allerdale.

Each framework produces a report that analyses the coastal processes and coastal response data in a bid to improve understanding and improve coastal erosion and flood risk analysis to support sustainable management decisions. The following baseline and annual reports have been, or are currently in the process of being, prepared: • Conwy: 1997-2005 Baseline; 2006 - 2009 Annual Reports. 2010 in production • Denbighshire: 2002-2005 Baseline; 2006 - 2009 Annual Reports. 2010 in production • Flintshire: 2002-2005 Baseline; 2006 - 2009 Annual Reports. 2010 in production • Wirral: 1998-2002 Foreshore Survey Report; 2003-06 Coastal Monitoring Report; 2007-08 Coastal Monitoring Report. • Sefton: 1999-2003 Baseline; 2004-2010 Annual Reports. 5

• Blackpool/Fylde: 2008-09 Baseline Process Monitoring Report. 2010-11 Annual report • Wyre: 2010 report in process, baseline data analysis undertaken • Lancaster: Morecambe and Heysham Beach Management Annual Report 2002; Baseline CERMS Report 2010-11 • Barrow: 2009-10 Baseline Process Monitoring Report, 2010-11 Annual Report. • Copeland: 2008-09 Baseline Process Monitoring Report. 2009-10 and 2010-11 Annual Reports. • Allerdale: 2009-10 Baseline Process Monitoring Report. 2010-11 Annual Report.

2.3 CERMS Strategic Monitoring

The collection, collation and dissemination of strategic cell or sub cell wide data is managed under a Regional Framework, which is split into two sub-divisions to recognise the specific and different requirements associated with strategic monitoring within Morecambe Bay compared to open coast areas. The regional framework for Morecambe Bay (Rossall Point, Fleetwood to Walney Island) is managed by Lancaster City Council whilst management for the remainder of the cell is carried out by Sefton Council. The Environment Agency manages some elements of the programme on behalf of Sefton Council, including LiDAR data collection.

The Morecambe Bay Strategic Monitoring (MBSM) was designed to co-ordinate strategic monitoring within Morecambe Bay and is primarily aimed at providing information in relation to bay wide changes in morphology and shoreline exposure.

Strategic data collected under CERMS comprises the following elements:

• Aerial Photography;

• LiDAR data;

• Recorded Tide Level Data;

• Modelled and Recorded Wave Data;

• Satellite Images (Morecambe Bay);

• Hydrographic surveys; and,

• Sediment Sampling

2.3.1 Vertical Aerial Photography A vertical aerial photograph survey of the whole of the Cell 11 coastline, excluding Morecambe Bay, was carried out in May 2010 at 25cm resolution. Planned photography of Morecambe Bay did not occur and a survey of the whole cell is planned for 2012.

2.3.2 Oblique Aerial Photography Oblique aerial photographs were collected across Cell 11 during March 2008 (coastal) and March 2009 (coastal and estuary to SMP boundary).

2.3.3 LiDAR data The majority of the cell 11 coastline has been flown for LiDAR during 2008-2010. The additional datasets collected during 2010/2011 focused on sand banks around the Mersey and Ribble Estuary.

• Great Burbo Bank and East Hoyle Bank, 6th March 2011

• Blackpool and Outer Ribble Estuary, 6th March 2011

• Taylor’s Bank, Sefton, 6th March 2011

2.3.4 Recorded Tide Level Data Recorded tide level data from a combination of Class A, Environment Agency and Privately operated gauges has been obtained, as defined in the CERMS Tide Gauge Review (2009) and in section 2.4 below.

2.3.5 Modelled and Recorded Wave Data Modelled wave data from the Met Office European Waters Wave Model (1988-2006) and from the extended UK Waters (Mesoscale) Wave model (2000-07) has been obtained under the CERMS arrangements for all available points in the Eastern Irish Sea, relevant to Cell 11. Data from the third-generation spectral model WaveWatch III (WW3) has been obtained for the Eastern Irish Sea for 22 points for 2008-2010. Data from the CEFAS wave buoy in Liverpool Bay (Nov 2002 to present) have also been obtained.

Two Nortek Acoustic Wave and Currents recorders were purchased and one deployed of the Blackpool coast in May 2010 and the other deployed off Formby Point in January 2011.

2.3.6 Satellite Images Strategic hydrographic, satellite and other survey data have been collected by Lancaster City Council under the Morecambe Bay Strategic Monitoring Arm of the Strategy. The programme was delayed and a number of these actions were not undertaken. The programme is currently working with UK Space Agency to review existing data and develop a programme of data collection for future years.

2.3.7 Hydrographic Surveys A hydrographic survey of the seabed off the Fylde coast, comprising extension of existing inter-tidal profiles and longshore transects was carried out by the Environment Agency in March 2008, this was repeated in March 2011.

Extensions of inter-tidal profiles across the (English) open coast were carried out during the summer 2010/2011, a total of 376 lines were captured. The lines generally extended to 3km from MLWN. Along each frontage a number of profiles were collected: Wirral MBC 42, Sefton MBC 54, Ribble Estuary 12, Barrow Council including Walney Island

49, Duddon Estuary 6 and Copeland Council 213

2.3.8 Sediment Sampling A cell wide sediment sampling exercise was started during Summer 2009 and was completed in March 2010. Samples were taken along existing profiles at the upper, mid and lower beach. Additional samples were taken offshore and in estuaries.

2.4 Summary of Data Held In Existing Sands Database The SANDS coastal monitoring database system is used by a number of Local Authorities within the Cell 11 region as a tool for storing, processing and analysing data collected 8 through the programme. Sefton Council, as client for the CERMS project, has provided a copy of the CERMS Sub-Cell databases that have been set up to coordinate data in the region for analysis as part of the project. Data extents, both temporal and spatial, have been reviewed in this section to provide an overview of the availability of SANDS data held within the CERMS region. For each Sub-Cell the data held within the database are summarised, and where other data are known to exist this is also discussed.

Some of the sub-cells databases contain wave refraction points which have been derived from modelling studies undertaken in the past within the area. These refraction points have not been included within the summary of available data as only measured physical parameters are discussed.

Where “Data not in SANDS” is shown, this highlights a location within SANDS where an instrument is known to be deployed but the reason for missing data is unclear.

2.4.1 Sub-Cell 11a

• 2 Class A tide gauges with up to date datasets held in SANDS within this sub-cell; at Liverpool (Gladstone Dock) and Llandudno database.

• The CERMS Tide Gauge Review (2009) recommends a further 7 tide gauges that should be incorporated into the CERMS programme. Additional data from these gauges has not been incorporated to date.

• There are 5 wind recorders within this sub-cell; data are currently held for three of these site; two records begin in 2007, whilst a third site, at Leasowe, came online in late 2009. Data are not currently held for the two remaining sites.

• There is 1 ADCP deployed in this sub-cell, however, the data are not currently available for this instrument.

• Two wave buoys are currently deployed in the area, those are:

- The Liverpool Bay WaveNet Datawell Waverider Mk III buoy, data available from download from Cefas; and,

- The RWE npower Datawell Waverider Mk III buoy data, data available from Channel Coastal Observatory.

• National Oceanographic Centre (formerly Proudman Oceanographic Laboratory) operate two radar systems:

- The WERA HF radar system was operatonal between 2005 and 2011. It operated from two land sites, and measures currents and waves over an area of up to 1600 km2; the two sites were based at Llanddulas/ Abergele, North Wales pointing northwards, and Formby, Merseyside pointing roughly west-south-west.

- A standard marine X-band radar was installed on a tower at Hilbre Island (Wirral) in 2003. It uses the shortest range and lowest power settings and is capable of imaging waves to a distance of 5km. It gives coverage across the lower Dee Estuary and into Liverpool Bay.

• There are 263 beach profiles that contain survey data for this sub-cell. Data from 67 profiles in Conwy, Denbighshire and Flintshire are not currently recorded in SANDS. The profiles shown on Figure 2.1 are in the CERMS version of SANDS – other data are currently not uploaded to SANDS but should be incorporated into CERMS analyses.

• A number of profiles throughout this sub-cell have been subject to surveys over the past century, with the earliest surveys dating back to 1916.

• The majority of profiles in this sub-cell have, for the most part, been surveyed at least annually since 1996 (generally bi-annually in Conwy).

• Profiles 11A02531 and 11A02537, at Ainsdale, were subject to intense data collection programme in 2009, to examine short term change.

• Hydrographic extensions of a number of profiles along the Sefton MBC frontage were surveyed during 2002 using a single beam scanner. In 2010 hydrographic lines were scanned using a swath scanner from MLWN to approx 3km offshore for 42 Wirral MBC lines, 54 Sefton MBC lines and 12 across the mouth of the Ribble Estuary.

Table 2.1 Sub-cell 11a fixed monitoring instruments

Instrument Instrument Location Data Collected Date Range Type Owner ADCP Rig POL 291520E, Unknown Unknown 396050N Datawell RWE Npower Rhyl Flats: Wave height, N/A - Not in Directional Renewables 293620E, direction, period, SANDS, but available Waverider Mk III 388400N water temperature from CCO website etc from 2007 onwards

Datawell CEFAS 311300E, Wave height, Data added to Directional 405700N direction, period, database 29/05/2003 Waverider Mk III water temperature to date etc Tide Gauge MDHC Alfred Lock Water Level Data available since 1934. Digital record available since 2000*

Tide Gauge EA North Corus Jetty Water Level July 1995 - Present* West (Summers Jetty)

* Recommended for incorporation to CERMS by CERMS tide gauge review, 2009

Table 2.1 Sub-cell 11a fixed monitoring instruments

Instrument Instrument Location Data Collected Date Range Type Owner Tide Gauge MDHC Eastham Water Level Data available since Lock 1941. Digital record available for 1980 & 81 and since 2000* Tide Gauge MDHC Gladstone Water Level Data available since Lock 1941. Digital record available since 2000* Tide Gauge MDHC Hilbre Island Water Level 1956 – 2009*. Digital record available from 1964-81 (intermittently) and since 2000. Unreliable data since 2007. Not maintained from 2009. Tide Gauge MDHC Burbo Wind Water Level Due to be Farm operational 2009 ** Tide Gauge POL Liverpool, Water Level November 1991 – Gladstone November 1998 Dock Tide Gauge POL Llandudno Water Level January 1971 – February 2009 Tide Gauge Port of Mostyn Mostyn Dock Water Level 2000 - Present* Environmental Metropolitan West Kirby Water Level, Wind August 2008 – Data Collection Borough of Marine Lake speed & direction, Present* (Data Station Wirral temperature and not yet verified for barometric pressure CERMS) Environmental Met Office Crosby Wind speed & Unknown Data Collection Coastguard direction, Station stn temperature and barometric pressure Wind Station Sefton Council Ainsdale Wind speed & May 2007 - May 2009 11

Discovery direction, Centre temperature and barometric pressure Wind Station Sefton Council Formby Wind speed & November 2007 - Blundell direction, June 2008 Avenue temperature and barometric pressure Wind Station POL Bidston Wind speed & N/A - Data owned Observatory direction, by POL temperature and barometric pressure

* Recommended for incorporation to CERMS by CERMS tide gauge review, 2009 ** It is understood that MDHC are having problems with the gauge at this location.

Table 2.1 Sub-cell 11a fixed monitoring instruments

Instrument Instrument Location Data Collected Date Range Type Owner Wind Station POL Hilbre Point Wind speed & N/A - Data owned direction, by POL temperature and barometric pressure Wind Station Metropolitan Leasowe Wind speed & From Nov 2009 Borough of direction, onwards Wirral temperature and barometric pressure HF Radar POL Llanddulas/ Wave height & From 2005 onwards Abergele, direction, current and speeds & direction Formby, Merseyside Marine Radar POL Hilbre Island Wave height & From 2003 onwards Direction

Total number of surveys of profile lines

Figure 2.1 Overview of data currently held in SANDS, database Sub-cell 11a

2.4.2 Sub-Cell 11b

• There are 2 tide gauges with datasets held in SANDS within this sub-cell; the earliest records begin in 1988.

• The CERMS Tide Gauge Review (2009) recommended a further 2 tide gauges that should be incorporated into the CERMS programme

• The number of profiles has increased from 65 to 78 in this sub-cell. The additions are along the Fylde Borough Council frontage. The profiles shown on Figure 2.2 are those in the database

• A number of profiles throughout this sub-cell have been subject to surveys over the past century, with the earliest surveys dating back to 1913 (Sefton) and 1956 (Blackpool).

• Since 1996 the majority of the profiles have been surveyed at least once in most years.

• 30 hydrographic bathymetry profiles were measured along the Fylde coast frontage, for the first time in March 2008, but not all of the data is presently in SANDS, due to quality control issues. In 2010 12 hydrographic lines were scanned using a swath scanner across the mouth of the Ribble Estuary.

Table 2.2 Sub-cell 11b fixed monitoring instruments

Instrument Instrument Location Data Collected Date Range Type Owner Tide Gauge Blackpool End of Pier, Water level June 2004 - June 2007, Council Blackpool issues with recent data quality Tide Gauge Stena Line, Fleetwood Water level February 1988 - April formerly ABP 1998 Tide Gauge EA North Fleetwood Water level July 2003 - Present* West (EA) Tide Gauge EA North Penwortham Water level Jul 2003 - Present* West Environmental Blackpool End of N Wind speed & June 2004 - June 2007 Data Collection Council Pier, direction, Station Blackpool temperature and barometric pressure

* Recommended for incorporation to CERMS by CERMS tide gauge review, 2009

Total number of surveys of profile

Figure 2.2 Overview of data currently held in SANDS, database Sub-cell 11b

2.4.3 Sub-Cell 11c

• There are three tide gauges in this sub-cell, whose records are incorporated in the SANDS database, with records beginning in 1964.

• The CERMS Tide Gauge Review (2009) recommends a further 7 tide gauges that should be incorporated into the CERMS programme.

• One wave buoy is currently deployed in the area; the Barrow WaveNet Datawell Waverider Mk III buoy. Data are available from download from Cefas and have been incorporated into the database.

• There are 179 profiles an additional 15 being established along the South Lakeland coastline with 164 beach profiles that contain survey data for this sub- cell. The profiles shown on Figure 2.3 are those in the CERMS version of SANDS. The earliest current beach profile survey records began in 1996. The 56 profiles between 11C01192 (Sunderland Point) and 11C01573 (Hest Bank) were all measured annually between 1996 and 2005.

• The majority of the remainder of the profiles, to North and South, have been measured at least annually since 2006. The only exceptions to this are the profiles along the west facing coast of Walney Island, which have only been surveyed once; in 2008. Historical surveys for this frontage are available from 1992-1999. They are not currently held within the CERMS SANDS database but should be incorporated into the database if possible.

• In 2010 hydrographic lines were scanned using a swath scanner from MLWN to approx 3km offshore for 49 Barrow Council lines including Walney Island.

Table 2.3 Sub-cell 11c fixed monitoring instruments

Instrument Instrument Location Data Collected Date Range in Type Owner SANDS

Tide Gauge ABP Barrow Water level March 2007 - Present* Intermittent Tide Gauge ABP Roa Island Water level historical data

Tide Gauge ABP Halway Shoal Water level available * Tide Gauge EA North Canal Foot Water level July 2003 - Present West

Tide Gauge EA North Glasson Wave data March 2004 – West Dock Present*

Tide Gauge POL / EA Heysham Water level January 1964 - February 2009

Tide Gauge EA North Heysham Water level June 2004 - June 2007 West Harbour

Tide Gauge EA North Leighton Water level August 2003 - West Beck (at Present* Arnside)

Tide Gauge Lancaster City Morecambe Water level July 2000 - Present* Council Stone Jetty

Datawell CEFAS Barrow Wave height, direction, Available in database Directional period, water

Waverider MkIII temperature etc

* Recommended for incorporation to CERMS by CERMS tide gauge review, 2009

Total number of surveys of profile lines

Figure 2.3 Overview of data currently held in SANDS, database Sub-cell 11c. Profile lines are normally surveyed twice a year, the chart represents the total number of surveys undertaken. 18

2.4.4 Sub-Cell 11d

• There are no fixed monitoring instruments deployed in this sub-cell.

• Historical short term data exists from a number of deployments off Sellafield and St Bees (ex CEFAS WaveNet) this should be incorporated in the SANDs database.

• There are 100 beach profiles that contain survey data for this sub-cell; survey records begin in 2004. The profiles shown on Figure 2.4 are those in the CERMS version of SANDS – other data are currently not uploaded to SANDS but should be incorporated into CERMS analyses.

• The majority of the profiles presently in SANDS have been subject to surveys since 2008 on an annual or greater frequency.

• In 2010 hydrographic lines were scanned using a swath scanner from MLWN to approx 3km offshore for 6 lines across the mouth of the Duddon Estuary and 213 Copeland Council lines.

Total number of surveys of profile lines

Figure 2.4 Overview of data currently held in SANDS, database Sub-cell 11d

2.4.5 Sub-Cell 11e

• The CERMS Tide Gauge Review (2009) recommends that water level data are incorporated into the CERMS at 2 sites in this sub-cell.

• There are 120 beach profiles that contain survey data for this sub-cell; survey records begin in 2004. The profiles shown on Figure 2.5 are those in the CERMS version of SANDS – other data are currently not uploaded to SANDS but should be incorporated into CERMS analyses.

• Current beach profile monitoring within Allerdale generally commenced in 2004 (2002 at Maryport) and within Copeland in 2008.Regular monitoring carried out by the Environment Agency between Whitehaven and Parton, between Workington and Flimby, in Moricambe Bay and between Bowness and Gretna commenced in 2006

Table 2.4 Sub-cell 11e fixed monitoring instruments Instrument Instrument Location Data Collected Date Range Type Owner Tide Gauge Whitehaven Whitehaven Water level No digital records – Harbour hard copy high Commissioners waters only* Tide gauge POL/EA Workington Water level February 1992 – March 2009* Tide gauge Silloth Harbour Silloth Water Level Currently only tide boards. New gauge (EA) due to be operational by 2010* Tide gauge EA Grass Dike Water Level New gauge due to be operational by 2010*

* Recommended for incorporation to CERMS by CERMS tide gauge review, 2009

Total number of surveys of profile lines

Figure 2.5 Overview of data currently held in SANDS, database Sub-cell 11e

2.5 Other local data collected but not currently recorded in SANDS

The following other monitoring data is collected by local frameworks and may be recorded in local SANDS databases but is not presently recorded in the CERMS SANDS database.

2.5.1 Sub-Cell 11a

• Topographic surveys of the inter-tidal zone have been recorded, generally bi- annually, since 1997 at Llandudno North Shore, Penrhyn Bay, Llanddulas and Kinmel Bay; since 2001at Colwyn Bay and since 2006 at Pensarn to Towyn.

• Data from 36 beach profiles in the part of Conwy in Cell 11(since 1997), 26 beach profiles in Denbighshire (since 2002) and 6 beach profiles in Flintshire (since 2002) are recorded in the Conwy CBC’s “Keyshore” system.

• There are historical beach profiles at over 100 locations in Conwy which date back to 1956.

• There are historical beach profiles at approximately 20 locations in Denbighshire which date back in places to 1983.

• Topographic surveys of the inter-tidal zone have been recorded, bi-annually, since 2002 at Rhyl (Denbighshire) and Gronant to Talacre (Denbighshire/Flintshire).

• Monitoring of the position of the seaward edge of the saltmarsh along the Welsh coast of the River Dee between Talacre and Connah’s Quay has been carried out bi-annually since autumn 2002.

• A topographic survey of the inter-tidal zone between Seaforth and Crossens has been recorded annually from 2001-2008 and bi-annually since 2009.

• Fixed offset monitoring of the position of the dune toe across Formby Point commenced in 1980. In 2001 this was superseded by continuous GPS survey along the toe line and is continuing. Similar exercises commenced at Hightown and Crosby in 2008.

• GPS monitoring of the cliff edge between Blundellsands and Hightown commenced in 2008.

• GPS monitoring of the position of the seaward edge of the “green beach” between Ainsdale and Southport was carried out annually between 2002 and 2008. Since 2009 up to 5 surveys per annum have been recorded

2.5.2 Sub-Cell 11b

• GPs monitoring of the position of the seaward edge of the “green beach” between Southport and Crossens has been carried out annually since 2002.

• No other specific monitoring known.

2.5.3 Sub-Cell 11c

• Monitoring of the position of the seaward edge of saltmarsh areas of foreshore has been carried out bi-annually at five separate locations between the River Lune and Silverdale since 1997. • Beach profiles between the Lune Estuary and Hest Bank, Morecambe have continued to be recorded bi-annually • Sampling of beach sediment composition at four locations between Silverdale and Teal Bay (1998-2010) and at eleven locations between Heysham and Cockerham (1999-2010). • No additional data has been acquired under the Morecambe Bay Strategic Monitoring programme, apart from strategic beach profiles around the bay. No remote sensing data (satellite imagery, aerial photography or bathymetric survey data) has been collected. • No other specific monitoring known.

2.5.4 Sub-Cell 11d • No other specific monitoring known.

2.5.5 Sub-Cell 11e • No other specific monitoring known.

2.6 Other Monitoring Programmes

2.6.1 Flood Forecasting The TRITON flood forecasting system for the North West Region (Solway Firth to the Wirral) was developed for the Environment Agency by PlanB and Posford Haskoning. The system integrates with the Agency’s existing data storage systems to collate wind, wave and tide data and undertakes offline transformations to provide hourly inshore forecasts of wave height, and forecasts of overtopping for specific sites. Wind/wave data are provided by the Met Office’s CS3 model with predicted tide and surge levels based on POL/Met Office model forecasts. Wave transformation to nearshore locations is carried out using the SWAN wave model which is run as a coarse model over the eastern part of the Irish Sea, together with more detailed nested models of the Solway, Morecambe Bay, Ribble, Duddon and Mersey. Defence overtopping calculations are made using the AMAZON model which runs a random wave train against the defence and calculates instantaneous peak overtopping rates and mean overtopping rates at two pre-defined points. The model uses SWAN 1D to transform the wave train from the outer boundary of the Amazon model to the sea defence. The results are then used to trigger tidal flood warning as appropriate, and have also been used to produce flood warning maps.

2.6.2 Liverpool Bay (Irish Sea) Coastal Observatory In 2001 Proudman Oceanographic Laboratory (POL) established a pilot Coastal Observatory in Liverpool Bay, funded by the National Environmental Research Council (NERC) with the aims of: a) understanding through effective continuous measurement and modelling, a coastal sea's response to natural and anthropogenic forcing and demonstrating the value of an integrated approach to marine environmental management; and, b) underpinning the ecosystem based approach to marine management and demonstrating the value of an integrated approach to coastal zone management. The Observatory integrates (near) real-time measurements with coupled models in a pre- operational coastal prediction system and displays the results on the web (www.cobs.pol.ac.uk). These data mainly relate to oceanographic parameters that are important to the driving of sediment transport processes. The web site also acts to collate data collected and supplied via other mechanisms (for example the National Tide and Sea Level Facility). The observatory has developed over the past seven years from its original research phase into an operational tool with linkages to a wide range of interests, including Coastal Defence and Shoreline Management, Water Quality, Navigation, Pollution etc. In addition the geographical area of coverage has increased outside of the confines of Liverpool Bay to the wider Irish Sea, which precipitated the change of name. Linkage with CERMS has developed during the period with the Observatory providing recorded wave data, bathymetry, wave and current measurements from HF and ‘X’ band radar systems etc., which can be utilised within CERMS.

2.6.3 Wavenet Wavenet is a strategic wave monitoring network that provides real time data from a number of wave buoys located adjacent to areas at risk from flooding around the coast of England and Wales. The network is funded by DEFRA and the Environment Agency in association with the Met. Office Two directional Waverider buoys are located within the coastal waters of the Eastern Irish Sea; the first is in Liverpool Bay, the second at Barrow. The buoys provide sea temperature, water depth and wave height, period and direction data at 30 minute intervals. The Liverpool Bay buoy has been operational since November 2002, whilst the Barrow buoy was installed in November 2009 and will be operational for one year. At Morecambe Bay Gas Field BHP Billiton operate a Saab downward-looking wave radar. The start date for this deployment was May 2005; it gives wind direction, wave height and period. The implementation plan on the project website describes the establishment of the network between 2002 and 2004, but does not presently indicate any further deployments planned for the future.

2.7 Data / Information Available from Linked Studies

2.7.1 Overview of CETASS The Cell Eleven Tidal and Sediment Transport Study (CETaSS) was commissioned to lead to a better understanding of the coastal processes including tidal currents, water levels, waves and sediment transport in the Cell Eleven region. The objectives of the study were:

• To reduce uncertainty relating to coastal processes and specifically tidal currents and sediment transport; and,

The whole of CETaSS was originally scheduled to be undertaken in advance of the SMP reviews, but due to funding difficulties only a Stage 1 scoping study, CETaSS Phase 1 report (2003) was possible before the SMP review commenced.

Stage 2 of the CETaSS study included two main phases: Stage 2 (i) a review of existing information and ongoing projects (Halcrow, 2010a) to identify the issues that need to be addressed, the approach required and a detailed approach for Stage 2(ii); and, Stage 2 (ii) which was made up of:

• A number of short duration activities that fed into the SMP2 stage 3 assessments; and,

• A number of longer term studies, the results of which will potentially feed into the SMP2 after consultation, and will also lead into future development and implementation of the SMP2 through the Action Plan.

The longer term CETaSS Studies that were.undertaken as part of Stage 2 (ii) include:

• A final summary report that pulls together the results from the more detailed studies to answer a range of questions previously identified for the Cell 11 region (Halcrow, 2010b)

• Regional tidal and sediment modelling - including offshore and littoral transport (Halcrow, 2010c, 2010d);

• A review of offshore banks – including characteristics and processes (Halcrow, 2010e);

• Estuary Morphodynamics - including morphology, processes, past evolution, sediment supply and future behaviours (Halcrow, 2010f, 2010g)

• More detailed modelling of the Ribble and Duddon estuaries (Halcrow, 2010h, 2010i);

• Morecambe Bay studies - including sediment fluxes, sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j); and,

• Assessment of coastal squeeze – including historical changes and likely future trends (Halcrow, 2010k).

Regional uncertainties

Sea level

The pattern of relative sea level along the Cell 11 coastline has been determined by the effects of the last glaciation which has led to marked regional differences during the last 10,000 years (the Holocene interglacial period). The north of the area has shown rising land levels due to the unloading of ice (isostatic rebound); whilst the south shows falling land levels. UKCIP09 projections also show similar trends across the region. Over the next 50 years, taking a 50% probability and a medium emissions scenario, the projections suggest an increase in relative sea level of 0.17m at Bangor and 0.145m at Solway. The larger rates of sea level rise in the southern parts of the region may increase erosional trends in areas where there are limited sediment supplies. Elsewhere in Cell 11 coastal evolution is more likely to be dependent on channel movements or changes in storm activity.

Regional tide and sediment transport

The new regional wave model of the north east Irish Sea is a significant improvement over previous regional or sub-regional models, and has been useful in investigating the specific effects of banks and estuary mouths and how they affect waves.

In the southern half of Cell 11, the potential sediment transport is directed from west to east, with an onshore component along the North Wales coast. Similarly, in the north, the transport is directed towards, and into, the Solway Firth. However, along the Cumbrian coast, from St Bees Head to Morecambe Bay, the potential sediment transport pathway is parallel to the shoreline in a southerly direction. The effect of this is evident when looking at the bathymetry of Cell 11 with narrow steeper shorelines in the north and much wider shallower margins in the south.

This general onshore transport of sand sized sediment provides a supply to the estuaries in Cell 11, especially the larger ones in the south. This is shown for the Mersey, Dee and Ribble estuaries which have extensive sand banks around their mouths.

The effect of climate change on the sub-tidal sediment transport due to potential increases in wave height and raised mean sea level has also been simulated. In general, there is a trend to increase the potential for transport towards the shore and for most areas. This suggests that there is a mechanism for the intertidal areas to respond to sea level rise and that coastal squeeze should not be a significant issue in the coastal environments in the southern part of the region. However, along parts of the Cumbrian coast there is no obvious mechanism to move sediment onshore and, combined with the higher exposure due to storm waves, this area, where the intertidal areas are already relatively narrow, could be subjected to increased narrowing with increasing mean sea level.

The regional wave model has been used to derive wave heights to feed into littoral transport formulae at 141 locations across the Cell 11 area. Confirming a number of drift divergences at Lytham, Walney Island and between the Duddon Estuary and Ravenglass Estuary. These littoral divides can vary by up to 2km, due to the variability of the annual wave climate. This explains why hot spots of beach erosion may vary from year to year.

o Enhanced erosion/accretion;

o Increased variability in beach profiles; and,

o Renewed periods of spit and barrier growth.

Sandbanks

Sand banks have been reviewed consistently across the Cell 11 region. Showing, with the exception of Constable bank, the main banks are associated with estuary mouths. All the nearshore banks are believed to be active under contemporary conditions and are likely to change their morphology in response to changes in hydrodynamic conditions. It is likely that the banks observed today in estuary mouths have been present in some form since sea levels reached their present level around 5000- 6000 years BP.

The banks associated with the mouths of estuaries are expected to remain in some form over the next 100 years continuing to offer protection to the adjacent shoreline.

Estuary Studies

The Cell 11 region contains 12 major estuaries and a number of smaller ones.

One of the most important characteristics is that the Cell 11 estuaries have shown positive sediment budgets. This has been driven by a flood dominance and a plentiful supply of sediment from offshore, and has meant that intertidal habitats have expanded in the estuaries, which has enabled large areas to be reclaimed for various human uses. These positive sediment budgets have also led to various interventions designed to facilitate the use of estuaries as ports. Such actions include dredging and channel training. Reclamation has also encouraged accretion by reducing tidal prisms and flow velocities in a number of estuaries.

Channel movements have been the main cause of saltmarsh erosion in the past, rather than coastal squeeze due to sea level rise. The prevention of this channel movement by the construction of training walls has led to substantial accretion in the Dee, Ribble, Wyre and Lune estuaries. Although they are not considered to be coastal flood or erosion risk management structures, removal or natural deterioration of the training walls would be expected to encourage renewed channel migration, intertidal erosion and possible export of sediment from the estuaries.

The potential for managed realignment shows that the largest increases in intertidal area would be likely to occur in the Dee, Mersey, Ribble and Duddon estuaries, which consequently would have the largest resulting sediment demand. However, the supply of sediment from offshore would appear to be sufficient to meet these demands. If these large increases in intertidal area were realised, then they would be likely to result in significant downstream changes within the estuaries as they adjust to the

new regime. In the more northern estuaries the intertidal areas tend to be higher in the tidal frame due to the sea level history and this will lessen the impacts of managed realignment.

In terms of coastal habitat loss, the term ‘coastal squeeze’ is commonly used. The concept of coastal squeeze has been critically evaluated and clarified. Coastal squeeze appears to be uncommon in the Cell 11 region in terms of open coast and estuarine areas. The Cell 11 estuaries have typically shown accretionary trends over the last few hundred years, if not longer. Thus coastal squeeze has not been a major factor in these areas.

Critically, there are a number of other causes for coastal habitat loss in addition to the presence of sea defences slowing the recession of the high water mark. In Cell 11, the role of changing positions of nearshore channels is likely to have been equally, if not more, important than sea level rise in the loss of habitats.

In the Cell 11 area, plentiful sediment supplies and onshore directed sediment transport suggests that at a cell-wide scale, coastal squeeze will remain a relatively minor issue in the future.

Sub-cell 11a – Great Orme’s Head to Southport

The regional sediment transport modelling shows that:

• Sediment transport pathways are generally from west to east;

• The Dee estuary is a strong sediment sink; and,

• The Mersey presently shows a small export of sediment.

The littoral transport modelling shows west to east transport of material along the north Wales coast, which confirms previous understanding. The Great Orme and Little Orme both act as drift divides, although Little Orme is only a partial divide since sediment bypassing can occur in the sub tidal zone.

Sand banks are important at a number of locations including Constable Bank, which influences wave levels on the Rhyl frontage; and the banks associated with the Mersey, which are also likely to play a role in reducing wave energy along the Sefton and north Wirral coastlines. The onshore movement of sediment will allow these banks to be maintained in the future, and thus continue to moderate wave energy on adjacent shores.

Sub-cell 11b – Southport to Rossall Point

The regional sediment transport modelling shows that offshore sediment transport paths are generally directed onshore from around Formby to roughly central Blackpool. North of here the pathways become more shore parallel and are directed northwards towards and into Morecambe Bay. On the Sefton coast the littoral divide lies some way south of the area from Victoria Road to the apex of Formby Point.

The Ribble is shown to be a key sediment sink.. With the effect of an increase in mean sea level an increase in the potential export of sediment in the main channel is predicted as well as an increase in the import of sediment on the southern flood channel and intertidal areas of the estuary. This

suggests that the main channel may widen under an increased tidal prism whereas the intertidal areas will accrete due to the increased import of sediment.

Large scale realignment on the southern side of the Ribble could reduce high water levels in the mid to upper parts of the estuary, which would represent a flood risk benefit.

The downstream increase in flow speeds is likely to lead to some erosion of the estuary channel in the subtidal or intertidal regions.

The offshore modelling confirms the existence of a flow divergence offshore off Blackpool. However, the littoral transport modelling demonstrates that the littoral drift divide is located to the south of Blackpool rather than at Cleveleys.

Sub-cell 11c – Rossall Point to Hodbarrow Point

The Bay acts as a sink for sediment with a net import on the southern side and a smaller net export on the northern half. The Lune Deep acts to channel much of the flow into and out of the Bay; on the eastern half of the Lune Deep transport has been shown to be into the Bay, whilst outside on the western part of the Lune Deep the transport is directed westward. This potentially maintains the depth of the Lune Deep as this behaviour implies there is a divergence zone for sediment. There is also a spoil site within the Lune Deep which could add to the net import into the Bay. Sediment is transported from the south towards the Lune Deep where it can be transported into the Bay showing this to be a major pathway of sediment into Morecambe Bay. Additionally, the Bay also receives littoral transport from the north and south. Sea level rise will increase the supply of sediment to Morecambe Bay.

Fluvial flows from estuaries of the Leven, Kent, Lune and Wyre appear to play a key role in influencing the position and movement of banks and channels in the Bay. The combination of low and high flows leads to significant morphological change and channel avulsion in unconstrained parts of the Kent and Leven estuaries and inner Morecambe Bay area. Other important factors include tidal currents and the occurrence of storm surges. Future changes in rainfall associated with climate change have the potential to increase channel mobility in the lower parts of the estuaries and the inner Morecambe Bay area. Further data capture is needed to document the variation in position of channels and banks.

Trends of cycles in channel position in response to driving hydrodynamic and fluvial conditions is needed

The net import of sediment to the Duddon estuary is dependant on both sub tidal and littoral transport. Sub tidal transport alone appears to indicate a small export of sediment (as the potential transport in the main channel dominates) at the mouth. However, with the inclusion of the littoral transport there is a net import overall. In the Duddon, the potential realignment areas lie relatively high in the tidal frame and hence have limited impact on the tidal prism.

Sub-cell 11d – Hodbarrow Point to St Bees Head

Transport in this region is dominated by net tidal transport from the northwest towards the southeast.

Like the Duddon estuary, the Ravenglass Estuary complex is shown to be a sediment sink for littoral transport with material being transported into the estuary on both the north and south sides of the mouth. Between these estuaries, littoral transport is generally to the north. From Seascale to Braystones, littoral transport direction is variable (since the shore is swash aligned), but northerly transport becomes more dominant towards St Bees Head, which is itself likely to act as a barrier to littoral transport

Sub-cell 11e – St Bees Head to Scottish Border

The net annual littoral transport direction is towards the north between St Bees Head and the Solway Firth. In the vicinity of the outer portion of the Solway Firth, the regional sediment transport modelling shows that offshore, sediment transport is directed towards the mouth from the west and exiting on the southern part towards the south. There is therefore a mechanism to supply the estuary but also to export sediment. Analysis suggests that the estuary morphology may be close to an equilibrium based on the prevailing dynamics. Around Mawbray to Southerness there is a constriction in the estuary and there is a change from mostly ebb dominated in the outer portion of the estuary to flood dominated transport in the inner part of the estuary. This is likely to lead to infilling of the inner estuary and a more complex system in the outer estuary which is typified by a highly variable system of banks and channels, similar to Morecambe Bay.

2.7.2 Overview of JPS The Joint Probability Study (JPS) was conceived following identification in the 1990’s by the five first round Shoreline Management Plans making up Cell 11, that region wide improvements in the estimates of joint probabilities between waves and water levels should be made. Subsequently, a scoping study was undertaken by Coastal Engineering UK Ltd in 2005. The aim of the Cell 11 Joint Probability Study was to produce consistent joint probability estimates for waves and water levels around the whole of the Cell 11 coastline. These can be used for boundary conditions feeding into subsequent studies, for example assessing performance of flood defences, coastal flood propagation models and preliminary design studies for coastal defences. Wave modelling was undertaken throughout the north-eastern Irish Sea encompassing the entire Cell 11 coastline at a coarse regional scale and finer nearshore model. The models were successfully calibrated against available wave buoy data. Out put from the wave modelling is in the form of up to 20 years of wave height, period and direction data at 52 locations around the Cell 11 coastline. Water level data was available from a series of Class A and other tide gauges. The Class A gauge data provided good temporal coverage but spatially it was not so good in the region. Alternative gauges exist, and together provide good spatial coverage but there were issues with not having a long record, unknown datums etc. Therefore for the joint probability analysis water levels were obtained from a Jeremy Ben Associates (JBA) surge model developed for the Environment Agency. This model provided a long record of water level data and was used to determine extreme water levels as part of a national study. This national study will provide the marginal

extreme water levels for use in the joint probability analysis along with the water level time series at coincident points to the wave time series data. The outputs from the JPS study (Halcrow, 2011a) were wave and water level time series along with joint probability curve data (waves and water levels) for a range of return periods at a number of locations.

2.8 Other Third Party Data Sources

There are a number of third parties actively collecting data in Cell 11. Where such data is publicly available CERMS needs to recognise its existence to avoid duplication of effort, and where possible easy access to the data should be arranged for CERMS partners.

Third party data available through the POL COBS website and historical data on the WaveNet and CCO websites is publicly available and has already been mentioned in the summaries above.

Several Port organisations collect data such as bathy surveys, tide gauge data and dredging quantities. Whilst some summary information is available to CERMS partners, through CERMS studies e.g. Tide Gauge Review, 2009 it would be useful for on-going efforts to obtain any relevant information, commercial terms notwithstanding. Future reports should include such information as and when it is procured.

Data has been collected relating to Environmental Impact Assessments (EIAs) for offshore wind farms, and some wind farms will include fixed instrumentation to facilitate their management and environmental monitoring. Recent consents have included the requirement to make monitoring data publicly available, and a summary of availability of such information should be added to future updates.

3 Cell Wide Baseline

3.1 Introduction This section provides a cell-wide view of coastal processes and flood and coastal erosion risk management issues. This section of the report is the combination of the overview presented in Baseline Report (Halcrow, 2010a), the results from analysis of data collected under CERMS and the outputs from subsequent studies such as the SMP2, the JPS and CETaSS. New information and data are presented in bold lettering while the text from the baseline report is in standard text.

Many of the management issues and gaps in understandings that occur are common to sub-cells throughout the region. This section therefore draws out these similarities and provides an assessment of the gaps in understanding following the specialist studies carried out in 2010/2011. It is hoped that future monitoring data will also help reduce the remaining areas of uncertainty in the Cell 11 region. This section also suggests how the gaps in understanding can be addressed either by ongoing studies or analysis of future monitoring data.

3.2 Existing Understanding

3.2.1 Study Area The North West England and North Wales shoreline is sub-divided using the following boundaries: • Sub-cell 11a: Great Orme’s Head to Southport (including the Clwyd, Dee and Mersey Estuaries); • Sub-cell 11b: Southport to Rossall Point (including the Douglas and Ribble Estuaries); • Sub-cell 11c: Rossall Point to Hodbarrow Point, Haverigg (including the Wyre, Lune, Kent, Leven and Duddon Estuaries); • Sub-cell 11d: Hodbarrow Point, Haverigg to St Bees Head (including the Ravenglass estuary Complex); and, • Sub-cell 11e: St Bees Head to the Scottish Border (including Moricambe Bay and the Eden estuary). A map of the Cell 11 frontage, showing the sub-cell divisions, is provided in Figure 3.1.

Figure 3.1 Overview of Cell 11 study area, showing SMP2 sub-cell frontages.

3.2.2 Physical and Oceanographic Setting Irish Sea Bathymetry

The Irish Sea is open to the Atlantic Ocean at the Northern Passage between Northern Ireland and western Scotland and St. George’s Channel between southern Ireland and south-western England. The Isle of Man and Ireland act to reduce the fetch and protect the North West coastline from the

full effect of waves in the Atlantic. The Irish Sea shelf is generally gently sloping with gradients of 1:1000 to 1:2000 (BGS, 1995). Figure 3.2 shows a plot of the regional bathymetry.

Figure 3.2 CETaSS Model bathymetry for North East Irish Sea area (mODN)

Eastern Irish Sea Bathymetry

The Eastern Irish Sea is to the east of the Isle of Man. Water depths shelve very gently eastwards across the area. The 20m isobath lies within a kilometre or two off the hard rock coasts and St Bees Head. Elsewhere, the 20m isobath lies many kilometres offshore and extensive intertidal flats are developed along the coastal fringe. The 2010 survey broadly agrees with the previous statements on bathymetry.

3.2.3 Overview of Offshore Processes Wind The prevailing wind direction across the eastern Irish Sea and north-west English coast is south- westerly (Pye and Blott, 2009). below presents a wind rose showing wind speed percentages for different sectors, based on all season data from 1989 to 2007. It can clearly be seen that the dominant wind directions are from the west to southwest. During the summer months the wind is more evenly distributed throughout the compass; the dominant winter storms however blow in from the Atlantic predominantly from the southwest.

Calm 7.59 %

wind speed (m/s) Above 20.000 17.500 - 20.000 15.000 - 17.500 12.500 - 15.000 10.000 - 12.500 7.500 - 10.000 5.000 - 7.500 2.500 - 5.000 5 % Below 2.500

Figure 3.3 Wind rose offshore from Barrow (based on data for the period 1989-2007)

Hydrodynamics Within the Celtic and Irish Seas the hydrodynamics are primarily controlled by a combination of bathymetry and sheltering from dominant waves and wind from the Atlantic (Robinson, 1979). The tidal energy of this region is dominated by the semi-diurnal lunar (M2) and solar (S2) tidal constituents. All the tidal constituents in the fourth diurnal and above (e.g. M4 component) are generated by non-linear, shallow water processes.

Tidal Propagation

The tide in the Atlantic Ocean propagates northwards along the western shelf edge into the Irish Sea via the St. Georges Channel and also propagates southwards into the Irish Sea via the Northern Channel. Propagation into the Irish Sea by both channels is virtually simultaneous (Myres, 1993). The M2 component of the tidal wave takes approximately 7 hours to travel from the shelf edge and across the Celtic Sea into the Irish Sea to Liverpool (Howarth and Pugh, 1983). A standing wave exists within the Irish Sea because of the meeting of the two tidal waves, one via the North Channel and the other through St. George’s Channel.

Tidal Range

Due to the tidal propagation described above, energy builds on the flood tide prior to forcing large volumes of water into the Irish Sea. As a result there are generally small differences between high tide times around Liverpool Bay and up to the Solway Firth. The Eastern Irish Sea experiences a semi-diurnal macro-tidal regime, where mean spring tidal range varies from 4.9m at Holyhead, to 8.4m at Liverpool, Morecambe and Silloth (Pye and Blott, 2009).

Tidal Currents

The tidal flows in the Eastern Irish Sea have been modelled by several previous studies often led by or involving researchers from Proudman Oceanographic Laboratory. Predicted currents from POL’s model are available on the coastal observatory webpage. The CETaSS study, which was linked to the development of the second round Shoreline Management Plan, undertook modelling of tidal flows in order to improve the understanding of sediment transport in the Cell 11 region. Figures 3.4 and 3.5 show depth average tidal currents at approximately peak flow on ebb and flood tides. Maximum flows occur in natural depressions e.g. Lune Deep or in man made channels e.g. entrance to River Mersey.

Figure 3.4 Peak depth averaged flood currents in Cell 11

Figure 3.5 Peak depth averaged ebb currents in Cell 11

Residual Currents

Residual sea bed currents in the north-eastern Irish Sea are directed towards the UK coast, with branches entering the Solway Firth, Morecambe Bay and estuaries of the Dee, Mersey and Ribble (Bowden, 1980). Across the Eastern Irish Sea, the flood tidal stream flows in a general easterly to north-easterly direction and the ebb flow is generally south-westerly. The residual current direction is a result of tidal asymmetry, with strong flood tidal currents and generally weaker, longer duration, ebb currents. The interaction of the M2 and M4 tidal constituents induces tidal current transport asymmetry which results in net landward sediment transport on and near the sea bed (Pingree and Griffiths, 1979). This contributes to landward transport of sediment into Liverpool Bay, the Dee, Mersey and Ribble estuaries, Morecambe Bay and the Solway Firth (Halliwell, 1973; Aldridge, 1997; Moore et. al., 2009). Figure 3.6 illustrates the depth average residual tidal flows over a 30 day period, which was calculated as part of the CETaSS modelling.

Figure 3.6 Residual current speed (spring-neap tide) (m/s)

Storm Surges

The Celtic Sea is exposed to Atlantic depressions that pass from west to east over the UK, and is particularly affected by secondary depressions which move north-eastwards over Ireland bringing

strong winds to bear on the West Coast sea areas (Lennon, 1973). The largest storm surges within the entire region are typically generated by depressions travelling from the south and south-west at speeds of approximately 75 km/hr. Within the Cell 11 region, the key features of storm surges (UKDMAP, 1998) are: • The highest surge elevations are located in Liverpool and Morecambe Bay (2m); and, • Maximum surge currents can be of the order of 0.6m/s. Modelling of the impact of a tidal surge on potential regional sediment transport was undertaken within the CETaSS modelling studies (Halcrow, 2010b). This modelling, which included both the effects of the storm surge and the associated waves and wind on sediment transport, generally showed increased transport towards the major estuaries. Additionally, alongshore transport on the north Wales’ coast and southwards transport from the Cumbrian coast towards Morecambe Bay were enhanced. The enhanced sediment transport is considered to be due to a combination of increased bed shear stresses as well as a larger volume of water entering the estuaries during the surge.

Water Levels

The extreme water levels from the Environment Agency’s 2011 study into extreme water levels around the coast. Locations around the coast of Cell 11 for points of along the coast are presented in Table 3.1 below. The sea levels include the affect of surge but not onshore wave action.

The Environment Agency extreme water levels shown in Table 3.1 is similar to, but lower than, the levels provided in the Extreme Sea Levels for North Wales (Atkins 2008). The new predictions from the Environment Agency are also similar to the predictions from the Extreme Sea Levels for Central North West England study (JBA Consulting 2007). However, the JBA water level predictions for North West England are generally slightly lower then the Environment Agency predictions.

Table 3.1. Extreme water levels for a selection of sites around the Cell 11 area (mOD). From the Environment Agency Feb 2011 (Coastal Flood Boundary Conditions for UK mainland and islands). Alongshore chainage is given for each site. The Environment Agency has stated that values provided by this study can be considered accurate to one decimal place. Return Probability Great Formby Southport Fleetwood Morecambe Walney St Bees Workington Period of level Orme Island Head (years) being reached in any year (%) CHAINAGE 1106 1178 1194 1232 1260 1312 1372 1388

1 100 4.71 5.25 5.4 5.59 6.16 5.32 4.97 5.09

10 10 4.99 5.62 5.8 5.98 6.59 5.68 5.31 5.44

25 4 5.09 5.76 5.95 6.14 6.76 5.82 5.44 5.58 50 2 5.18 5.87 6.07 6.27 6.9 5.93 5.55 5.69

100 1 5.26 5.97 6.17 6.39 7.03 6.03 5.65 5.79

250 0.4 5.38 6.09 6.31 6.55 7.2 6.16 5.78 5.93

500 0.2 5.47 6.19 6.41 6.68 7.33 6.26 5.88 6.03

Waves

The wave climate varies throughout the region due to the differing levels of protection afforded by landmasses (e.g. Ireland, Anglesey and the Isle of Man) against waves originating from the Atlantic. These land masses also control fetches for locally generated waves and offshore banks provide sheltering to the coastline. The major characteristics are: • The predominant wave direction varies throughout the region, being from the west- northwest in Liverpool Bay, west-southwest at the entrance to Morecambe Bay, south westerly on the Cumbrian coast (Pye and Blott, 2009); • Minimum wave heights occur in areas sheltered from the dominant south-westerly waves, such as the lee of headlands and estuaries; • The sheltering of the coast from St. Bees Head to Great Orme’s Head from waves of large fetches by the Isle of Man (Horn, 1993); • The annual 10% exceeded wave height can range from 1.0 m upwards;

• Values of Hs rarely exceed 4m and mean zero crossing periods rarely exceed 8 seconds (Pye and Blott, 2009); • The 50 year wave height (Hs) in Liverpool Bay is between 3m and 6m depending on location (Shoreline Management Partnership, 1999a); • Smaller waves (1.4m) affect the Solway Forth, while wave height increases to 1.7m for the North Wales coast, the Dee and Mersey (BGS, 1995); and, • Wave roses show that predominant waves come from the sector with the longest fetch, which is from the south-west for Workington and Eskmeals, from west-south-west for Cleveleys and from the north-west at Hoyle Bank and Kinmel Bay (Figure 3.7).

Figure 3.7 Wave roses for the Cell 11 coastline (from the JPS study (Halcrow, 2010))

The recently completed wave modelling with the Joint Probability Study (JPS) (Halcrow, 2011a) is providing around 20 years of consistent modelled nearshore wave conditions for around 50 locations distributed around the open coastal of Cell 11. The JPS provides a significant improvement over previous regional or sub-regional models, which may not have incorporated the influence of the Isle of Man if the European Met Office wave model had been used for boundary conditions. This wave model, in conjunction with a new regional hydrodynamic model, has allowed the consistent assessment of sediment

transport across the whole region, both in terms of the sub-tidal and littoral regions. The regional wave model has also been useful in investigating the specific effects of banks and estuary mouths, and how they affect wave conditions.

The wave heights calculated for the JPS for a range of locations is presented below

Table 3.2 Significant wave heights (in metres) for selected sites on the Cell 11 coastline from the JPS (Halcrow 2011).

Little Point Mid Formby Blackpool Mouth of Duddon St Mid Orme of Wirral Point Morecambe Mouth Bees Solway Ayr Bay Head

Return JPS Pt JPS Pt JPS Pt JPS Pt JPS Pt 32 JPS Pt 37 JPS Pt JPS Pt JPS Pt Period 5 16 21 29 42 48 56

1 4.76 5.18 5.27 5.36 5.25 5.50 5.24 5.06 5.57

5 4.95 5.41 5.53 5.64 5.51 5.78 5.49 5.29 5.85

10 5.04 5.51 5.63 5.75 5.62 5.90 5.60 5.39 5.97

20 5.12 5.60 5.73 5.87 5.73 6.02 5.71 5.49 6.10

50 5.23 5.73 5.86 6.02 5.87 6.18 5.86 5.61 6.28

100 5.32 5.82 5.96 6.13 5.97 6.30 5.97 5.71 6.41

200 5.41 5.91 6.05 6.23 6.06 6.42 6.07 5.80 6.55

500 5.52 6.04 6.17 6.37 6.19 6.58 6.21 5.92 6.74

1000 5.61 6.13 6.26 6.48 6.28 6.70 6.31 6.01 6.89

10000 5.92 6.43 6.53 6.79 6.56 7.09 6.64 6.29 7.40

Sea-bed Sediments

Prior to the early Holocene marine transgression, the Eastern Irish Sea was covered by a complex suite of clastic sediments laid down by the retreating glaciers and their associated fluvial systems. With the post-glacial rise in sea level these sediments were reworked and additional sediment may have been brought into the area from the Western Irish Sea.

Sea-bed sediments vary considerably in character within the eastern Irish Sea and the Solway Firth. However, there is a general trend from gravels, sandy gravels and gravelly sands in the west, sands and muddy sands in the central zone and sandy muds in the east (Figure 3.8) (BGS, 1995). Sand is dominant close to the coast, with concentrations of gravel along high energy shorelines and muds in sheltered estuaries.

Figure 3.8 Distribution of sea-bed sediments. Classification after Folk (1954). Modified from Jackson et. al., (BGS 1995)

Sediment Transport

Previous studies suggest that there has been large-scale, long-term movement of sediment from the western part of the Irish Sea to the eastern Irish Sea. Consequently, Liverpool Bay, Morecambe Bay and the Solway Firth, as well as their associated estuaries have acted as sediment sinks. This is supported by broad scale modelling work such as that by Pingree and Griffiths (1979), see Figure 3.9.

Figure 3.9 Mean sea bed bottom stress. After Pingree and Griffiths (1979)

The CETaSS regional hydrodynamic and subtidal sediment transport modelling (Halcrow, 2010c) has allowed the simulation of present day conditions and the potential impacts of future climate change in terms of a rise in sea level and an increase in wave height. The model clearly shows the subtidal sediment transport pathways which are key to understanding the large scale sediment budgets for the coastal region. In the southern half of Cell 11, the potential sediment transport is directed from west to east, with an onshore component along the North Wales coast. Similarly, in the north, the transport is directed towards, and into, the Solway Firth. However, along the Cumbrian coast, from St Bees Head to Morecambe Bay, the potential sediment transport pathway is parallel to the shoreline in a southerly direction. The effect of this is evident when looking at the bathymetry of Cell 11 with narrow, steeper shorelines in the north and much wider, shallower margins in the south. This general onshore transport of sand sized sediment provides a supply to the estuaries in Cell 11, especially the larger ones in the south. This is shown for the Mersey, Dee and Ribble estuaries which have extensive sand banks around their mouths.

Locally, sediment transport patterns along the Cell 11 coast are complex, influenced by waves and tides interacting with the sea bed and coastal geomorphology. A preliminary conceptual model of the major regional sediment transport pathways based on a literature review undertaken within CETaSS is shown in Figure 3.10; it should be noted, however, that at some localities littoral drift, particularly close to the shoreline where it can be primarily influenced by wave driven behaviour, may change direction dependant on the prevailing wind directions.

Figure 3.10 Preliminary schematic representation of the principal marine and fluvial sediment transport pathways in the eastern Irish Sea (Pye and Blott, 2009)

The most recent CETaSS modelling supports the overview given by Pye and Blott (2009) in Figure 3.10. The sediment transport modelling for ‘flood tide peak pure tidal sand transport’ is shown in Figure 3.11.

Figure 3.11 CETaSS Flood tide peak pure tidal sand transport

As part of the CETaSS modelling the magnitudes of sediment transport were estimated (Halcrow, 2010c) and are presented in Figure 3.12.

Figure 3.12 CETaSS Yearly potential sediment transport across transects in the North East Irish Sea (1000m3). Representative tide simulation with tide and wave forcing. Yearly potential sediment transport vectors are shown as reference on the right.

A summary of present understanding of regional sediment movement in the Cell 11 is given below. The interpretation is based on information previously discussed in the Baseline Report (Halcrow, 2010a) and additional results obtained by CETaSS (Halcrow, 2010b) and the JPS (Halcrow, 2011a).

Liverpool Bay

Figures 4.2 and 4.4 in Section 4 of this report contain updated plans showing the present conceptual understanding of behaviour in Liverpool Bay)

• Easterly transport of sand and gravel along the North Wales coast;

• The average net potential littoral transport is directed in an easterly direction along the north Wirral shoreline.

• Some potential movement of gravel offshore during storms;

• Minimal supply of sediment into this area from offshore;

• Large volumes of sand held in offshore banks (Constable Bank, West Hoyle Bank);

• The Dee, Mersey and Ribble estuaries are significant sediment sinks;

• The slightly deeper water between the East Hoyle and Great Burbo banks may mark a divide between two offshore sediment transport cells;

• A drift divide in the vicinity of Formby Point with sand transported southerly towards the Mersey and northerly towards the Ribble, although the modelling could not determine the exact location of the drift divide;

• Formby Point is a major store of sediment, at present it is eroding and the beach in front is losing volume.

• The results from the sediment transport modelling, which included the effect of waves as well as tides are presented in Halcrow, 2010h. The main findings are that the mouth of the estuary behaves as a sink for sediment as there is a convergence in sediment pathways. These pathways all converge in the mouth of the Ribble where there are large areas of intertidal sand banks. There is believed to be little sediment bypassing the estuary as the mouth acts as a strong sink and,

• A longshore drift divide was known to exist within the littoral zone on the Fylde coast near Blackpool / Cleveleys. The CETaSS offshore sediment transport modelling confirmed the existence of a flow divergence offshore of Blackpool. However, the littoral transport modelling suggests that the net littoral drift divide is located to the south of Blackpool rather than at Cleveleys. In reality the location will be variable in response to the variable conditions each year.

Morecambe Bay

Figure 4.6 in Section 4 of this report provides an updated plan showing the present conceptual understanding of behaviour in Morecambe Bay)

• The regional sediment transport modelling illustrates that Morecambe Bay acts as a sink with a net movement into the Bay from offshore and the south and to a lesser extent from the north;

• The fluvial flows from estuaries such as the Leven, Kent, Lune and Wyre appear to play a key role in influencing the position and movement of banks and channels in Morecambe Bay. Other important factors include tidal currents and the occurrence of storm surges;

• Sediment transport within Morecambe Bay is dominated by tidal currents;

• Within Morecambe Bay transport is mostly onshore into the inner parts of the bay;

• There is an export of sediment across the northern half of the mouth of the Bay and an export outside the Bay in the western part of the Lune Deep;

• Morecambe Bay also receives littoral transport from beaches and inter-tidal areas to the north and south of the bay;

• The Lune Deep remains open due to focusing of tidal flows; and,

• The CETaSS littoral transport modelling confirms the existence of a net drift divide in the centre of Walney Island and also shows how it has moved back and forth alongshore by some 2km over the last 18 years in response to changing annual wave conditions.

Cumbria

Figures 4.8 and 4.10 in Section 4 of this report are updated plans showing the present conceptual understanding of behaviour along the Cumbrian Coast)

• Coarse sediment does not move from the west across the Eastern Irish Sea Mud Belt onto this coast;

• The regional sediment transport modelling within CETaSS shows that offshore, transport in this region is dominated by net tidal transport from the northwest towards the southeast, i.e. towards Morecambe Bay. Closer to the shore and further to the south the magnitude of the transport reduces;

• Between the Duddon estuary and Ravenglass Estuary Complex littoral transport is generally to the north;

• From Seascale to Braystones, the littoral transport direction is variable (since the shore is generally swash aligned), but northerly transport becomes more dominant towards St Bees Head, which is itself likely to act as a barrier to littoral transport;

• St Bees Head marks a major longshore drift divide. The littoral transport modelling shows that St Bees Head exhibits zero littoral transport rates due to the rocky nature of the headland; and,

• The main source of sediment is from erosion of the boulder clay cliffs and from erosion of the nearshore zone.

Solway Firth

(Refer to Figure 4.10 in Section 4 of this report for a conceptual understanding overview of the Solway Firth)

• The Solway Firth is a major sink for sand and, in its upper reaches, for mud

• The net annual littoral transport direction is towards the north between St Bees Head and the Solway Firth;

• In the vicinity of the outer portion of the Solway Firth, the regional sediment transport modelling shows that offshore, sediment transport is directed towards the mouth from the west and exiting on the southern part towards the south. There is therefore a mechanism to supply the estuary but also to export;

• Around Mawbray to Southerness there is a constriction in the Solway Firth estuary, and there is a change from mostly ebb dominated in the outer portion of the estuary to flood dominated transport in the inner part of the estuary. This is likely to lead to infilling of the inner estuary and a more complex system in the outer estuary;

• The Solway Firth has a significant fluvial input which supplies sediment and which may also influence channel morphology in a similar manner to that which is believed to occur in Morecambe Bay;

• The modelling confirmed the Inner Solway as a strong sediment sink; and,

• New analysis suggests that the Solway Firth estuary morphology may be close to an equilibrium based on the prevailing dynamics.

Climate Change

The Cell 11 Regional Studies (CETaSS and JPS) looked into how climate change might affect the coastal dynamics of Cell 11. The effect of climate change on the sub-tidal sediment transport due to potential increases in wave height and raised mean sea level has also been simulated with the models. In general, there is a trend to increase the potential for transport towards the shore for most areas. A separate assessment of sediment budget shows that in Cell 11, this offshore supply of sediment is critical in maintaining habitats in the face of sea level rise. This suggests that there is a mechanism for the intertidal areas to respond to sea level rise and that coastal squeeze should not be a significant issue in the coastal environments in the southern part of the region. However, along parts of the Cumbrian coast there is no obvious mechanism to move sediment onshore and, combined with the higher exposure due to storm waves, this area, where the intertidal areas are already relatively narrow, could be subjected to increased narrowing with increasing mean sea level.

In terms of potential climate change impacts, the littoral transport modelling suggests that a 10% increase in wave height could lead to a 19% increase in littoral transport rate. This could lead to a number of impacts including: enhanced erosion/accretion; increased variability in beach profiles; and renewed periods of spit and barrier growth.

3.3 Issues and Uncertainties

The recent Cell 11 Regional Studies (CETaSS and JPS) have gone a long way in addressing the uncertainties identified in the Baseline Report, as summarised in Table 3.1.

Table 3.1 Uncertainties in present regional understanding Issue / Uncertainty Monitoring / studies that provide data/information to address uncertainties CERMS CETaSS JPS Other Rate of sea level rise across the area – a hinge line is believed to extend through Morecambe Bay with areas to the north and south reacting differently in terms of isostatic rebound Better definition of tidal current behaviour

Implications of changes in mean wind-wave conditions including consideration of aeolian transport

Availability of nearshore sediments and the likelihood that these could be moved onshore under a scenario of rising sea levels Role of Liverpool Bay and feeder estuaries as a sediment sink

Influence of the estuaries on adjacent open coast shorelines.

Difference between measured and modelled nearshore wave conditions exhibits a general weakness in shallow water transformations Impact of offshore banks and channels on shoreline behaviour and changes that can occur over decadal timescales

Insufficient information on sediments and their variability within approximately 3km of the shoreline

The role of surges in shoreline evolution

Joint probability of waves and water levels

Understanding of littoral drift behaviour for whole of Cell 11 with improved coverage and consistent approach

Following CETaSS and the JPS a number of uncertainties still remain, as shown in Table 3.1 which will be best addressed through the collection of additional local data. In order to better understand the various aspects of coastal systems within Cell 11 it is necessary to gain new data on a number of features. This data capture should feed into the Cell Eleven Regional Monitoring Strategy (CERMS) programme, which should provide more comprehensive data to the next review of the SMP. In many instances further data are required before full value can be derived from additional studies. It would be desirable to have more information on the following:

• Tide gauge data – the recommendations of the tide gauge review (Halcrow, 2010) should continue to be implemented within CERMS. Longer term tide gauge data would provide more information on extreme water levels and act as a record for any sea level rise.

• Wave data

• Sediment provenance

• Sandbanks (specifically their evolution in location and form)

• Estuary parameters

• Bathymetry

• Coastal Squeeze

More information about the requirements for further studies is provided in Section 15 of the CETaSS Main Report. The future plan for the CERMS monitoring is presented in Section 3.3.1 below.

3.3.1 CERMS Programme Design 2011 to 2016 The following text provides an overview of the plan for CERMS in the coming years Review of Risk Based Approach to Programme Design The risk based approach to programme design adopted for the original CERMS project plan provided the basis for identifying the temporal frequency and/or intensity (spacing) of the primary monitoring elements i.e. • Inspection of coastal defence assets • Topographic and bathymetric profiles • Larger scale bathymetric surveys • Sampling of sediments • Locations for collection of hydrodynamic data Definition of the varying level of risk across cell 11 was based on the characteristics relevant to each of the management units defined in SMP1. Key points arising in relation to the risk assessment carried out and its subsequent use in definition of monitoring actions were: • It is important that the comprehensive review of the characteristics (i.e. the source, pathway, receptor, consequence assessment) of each Management Unit is only used as guidance for the appropriate monitoring regime for that frontage. • To be consistent, it is important that the results of all the major elements of such a programme are used to provide increased knowledge of the "risks" of

coastal flooding and erosion, and how they are changing. To this end, the specification of the monitoring plan should be linked to a clear plan for: o Quantifying and disseminating present levels of "risk", as revealed by initial "baseline" monitoring; and o Assessing and presenting information on the changes in risk as the monitoring programme proceeds. o Information obtained on these two important outcomes of the monitoring should then be used to refine the “risk ratings” for the Management Units, as part of a periodic review of the monitoring programme. It is important that the monitoring programme is carefully reviewed after the first few years of operation. With completion of SMP2 in 2010 and the re-defining of frontages for policy definition as Policy Units, the exercise has been repeated for the purposes of informing the project plan for the next five years. The methodology for risk assessment is as previously adopted (Coastal Engineering, 2005). Plans showing the updated risk level for each policy unit are provided in Figure 3.1, Figure 3.2 and Figure 3.3 and, for the south, central and northern sections of frontage, respectively.

Programme Influences Following the commencement of CERMS in 2007-08, the data it has provided has been used to inform a number of different projects and planning initiatives both locally and regionally within Cell 11. Particularly the data has been used to inform the two regional studies, that were identified within the project plan – the Cell 11 Tidal and Sediment Study (CETaSS) and the Cell 11 Joint Probability Study (JPS) which in turn have provided/will provide guidance to inform the development of CERMS over the next five years. In addition CERMS data has been used to inform the review of the Shoreline Management Plan (SMP2).

CETaSS The primary objectives of the Cell Eleven Tidal and Sediment Transport Study (CETaSS) were: • To reduce uncertainty relating to coastal processes and specifically tidal currents and sediment transport; and, • To provide coastal process information and understanding to improve the evidence base for selection of future flood and coastal erosion risk management (FCERM) policies in the Shoreline Management Plan and subsequent Strategies for investment in risk reduction measures. The principal outcomes from CETaSS relating to development of CERMS are summarised in Table 3.2 below: Table 3.2: Recommendations for CERMS arising from CETaSS Study Data Element Recommendation Tide Gauge The recommendations in the recent Cell 11 tide gauge review (Halcrow, Data 2010d) should be taken forward through the CERMS programme. Wave Data 1. It would be beneficial to obtain more nearshore wave data to improve future validation of wave model results over the intertidal zones, around the mouths of estuaries and in parts of Morecambe Bay where the strong tidal flows need to be accounted for in model predictions. The locations for data capture should be prioritised in relation to coastal flood and erosion risks. Suggested priority locations should include

nearshore data along the Cleveleys to Rossall Point frontage, the Morecambe frontage, North Wirral coast, and the Llanddulas to Prestatyn frontage. Data collection should be for a period of at least a year, followed by comparison of measured data against model predictions. 2. It is recommended that time series archived data from the Met Office new WaveWatch III forecasting model at all nearshore points should be obtained annually and stored in the CERMS database for comparison with measured data and for use in analysis of coastal change data. Sediments 1. Data should be collected, in association with other agencies e.g. BGS, to update mapping of sediments particularly in offshore areas to identify whether there will be sufficient sediment available to provide for future requirements. This work could include sampling and profiling surveys, possibly in conjunction with bathymetry surveys for specific areas assessed on a risk basis, guided by the results of the modelling to confirm the availability of sediment for transport and the modelled pathways. 2. Long term suspended sediment concentration data, measured close to a number of estuary mouths, would be extremely useful to examine suspended sediment concentrations and fluxes into estuaries. This can be a difficult and expensive parameter to measure over long time periods as regular instrument maintenance is required. This may be best taken forward on a trial basis for a particular estuary, in collaboration with a University or NOC. The coastal group could seek to collaborate with others when or if data collection campaigns are being planned for tidal power or other estuary studies. Comparison and analysis of concentrations with meteorological and wave data would also Sandbank A combination of LiDAR and hydrographic surveys should be used to Surveys monitor the low water extents of sandbanks that may play a critical role in limiting shoreline exposure conditions. This should focus on the banks considered most important in terms of managing coastal flood risks, so the priority would be the bank system extending south east from Constable Bank and the Shell Flat. Estuaries Combined LiDAR and hydrographic surveys of estuaries should be carried simultaneously to provide a complete snapshot of estuary form and condition. Morecambe Continuation and development of the present system of LiDAR surveys, Bay bathymetric surveys, aerial photographs and satellite images should be used to inform understanding of the changing morphology in Morecambe Bay. Bathymetric 1. Bathymetry data in some areas is old, scarce or non-existent (e.g. Surveys northern part of Morecambe Bay and parts of the Solway Firth). This should be addressed in future through improvements to coastal monitoring being put in place through CERMS. 2. In addition to establishing baseline data, for the whole shoreline, hydrographic surveying of beach profile extensions or multi-beam surveys of the nearshore area need to be continued on a regular basis in order to improve the understanding of ongoing change in nearshore and intertidal zones. These repeat surveys could be prioritised to the high risk frontages from the regional CERMS risk assessment, but they need to consider linked source / sink areas rather than just the immediate areas near the risk zones. As noted in estuaries above the bathymetric surveys should be co-ordinated as far as practicable with airborne

LiDAR surveys of the intertidal areas or topographic surveys. Coastal The assessment of habitat losses and gain requires the capture of new Squeeze LiDAR and aerial photography data for intertidal areas, plus the ongoing collection of beach profile data. This data to be provided through CERMS.

CETaSS also included the setup and calibration of a regional (broad-scale) wave model of the NE Irish Sea and a nearshore wave model that covers the whole of the coastline in Cell 11. The purpose of the broad-scale model was to provide boundary conditions to the nearshore model along the Cell 11 coastline, which will in turn be used to derive marginal extreme wave conditions and joint probabilities between wave heights and water levels along the Cell 11 coast under the JPS and to support the investigations carried out under the CETaSS study. The broad-scale model setup and calibration and verification used data from the Met Office’s UK Waters hindcast model and measured data from the CEFAS WaveNet archive, supplied through CERMS. The nearshore wave model for the Cell 11 coastline was also setup and calibrated against with the relevant Met Office model and CEFAS recorded wave data, plus additional local measured data that was available. CETaSS identified that “The regional wave modelling developed through the CETaSS and linked JPS could be continued annually under CERMS to provide a longer set of consistent regional modelled data suitable for use in boundary conditions for local models. However, the Met Office has recently switched to using the new WaveWatch III model and discontinued use of the European Waters model that was used to provide the 18 year set of boundary conditions for the present study. It is recommended that when a suitable period of simulated regional data become available from the new Met office model a comparison between it, the nearshore climates from the Halcrow model and measured data should be undertaken. Following this intercomparison, a decision can be made over the need for further regional nearshore wave modelling”.

Cell 11 JPS The Cell 11 JPS (Halcrow, 2011a) had a delay in reporting due to delay in the availability of results from the Joint DEFRA/Environment Agency Flood and coastal erosion risk management R&D programme – Project SC060064 – Development and Dissemination of Information on Coastal and Estuary Extremes, which provided: • A consistent set of extreme sea levels around England, Wales and Scotland • A consistent set of wind and swell waves around England, Wales and Scotland • Best Practice Guidance on applying these datasets. As a result recomendations for the CERMS programme design were made before the JPS was published.

4 Sub-cell Baselines

4.1 Introduction This section presents baseline reports for sub cells 11a to 11e, updated with additional information from local monitoring reports and studies, which has become available. For each sub-cell the following topics are covered:

• Existing understanding;

• Issues and uncertainties;

• Interpretation of existing monitoring data;

• Recommendations; and,

• Conclusions.

Information from the 2010 annual monitoring reports is included in this section in bold type. It is intended that these sections of the report act as an overview of current behaviour understanding against which future monitoring reports will be compared. This will allow newly collected data to be checked against existing knowledge and also allow for future annual reviews to provide improved understanding or reduce uncertainty in the baseline conceptual models.

4.2 Sub Cell 11a

4.2.1 Summary Sub-Cell 11a (Figure 4.1) extends between Great Orme’s Head on the North Wales coast and Southport. At the time of writing the 2010 update, for Sub Cell 11a only the 2010 Report on the Sefton coast (Sefton 2011) has been provided. As a result the update will only relate to the Sefton Coast. The understanding of the coastal dynamics of other Local Authority areas is considered unchanged.

Figure 4.1 Location map of sub-cell 11a The main coastal features are: • A backshore comprised of limestone promontories, clay cliffs and low-lying alluvial plain;

• A foreshore composed of sand and shingle beaches; • Two dune systems: Point of Ayr spit at the mouth of the Dee Estuary and the significant Formby Dune system extending from Crosby to Southport; • Two major estuaries; the Dee and Mersey; and, • Two smaller additional estuaries of the River Clwyd and the River Alt. The predominant shoreline response is of erosion with net longshore drift from west to east occurring across the North Wales and Wirral shorelines and most significantly beach and dune erosion across Formby Point. However there are some of areas where sediments are accreting notably on East Hoyle Bank and along the sand dune frontages that flank Formby Point. The Dee estuary is also a major sediment sink, whilst the channel into the mouth of the River Mersey requires dredging to maintain navigable depths. Between Great Orme’s Head and Rhos Point the coastline is strongly controlled by the alternating hard and soft geology, which has led to the creation of a shoreline dominated by headlands and bays. This differs from the adjacent stretch extending to the Point of Ayr, which is one larger embayment with gently curved cuspate bays. The North Wirral Coast and Sefton Coast are both estuary-dominated shorelines but offer different open coast geomorphology and behavioural characteristics, each of which will be influenced by the two major estuaries.

4.2.2 Existing Understanding Wave and Tidal Conditions

The predominant wave direction is from the north-west as is the tidal residual current. Tidal levels and wave heights increase slightly from Great Orme’s Head to Formby Point. Wave action in Liverpool Bay is limited by the relatively small fetch lengths in the Irish Sea at this point due to the presence of the Isle of Man and Anglesey (Hedges et. al., 1991). The annual mean wave height is only 0.8m, but during the winter month’s significant wave heights of 5m (periods 6 to 8s) have been observed (McDowell and O'Connor, 1977). The annual 10% exceedance significant wave height is 1 to 2.0m. The mean tidal range is 6.5m at Liverpool. Real time wave data was obtained by Sefton for the whole of 2010 from the CEFAS/ NOC and wave rider buoy in Liverpool Bay. Data was also obtained from the Met Office WaveWatch 3 model. The 2010 monitoring showed the predominant wave direction was from WNW. Interpretation of the data showed that: • In 2010 data was recorded for just under 93% of the time. The maximum storm wave condition recorded had a height of just under 5.0 metres and waves in excess of 4.0 metres in height recorded between 11/11/2010, 20:00hrs and 12/11/2010 06:30 hrs. • The CEFAS wave climate for 2010 appears similar to the 2003 climate with nearly 80% of recorded waves less than 1.0 metre in height, compared to under 70% in the longer term (Nov 2002-2010) climate. Also there were only 20% of waves between 1 and 3 metres in height compared to 30% in the long term and 0.5% of waves in excess of 3.0 metres compared to 1% in the long term.

Pingree and Griffiths (1979) have shown that the tidal current mean bed stresses are directed into large bays, e.g. Liverpool Bay. This arises from the combination of M2 and M4 tides creating asymmetry in the tides, with a strong flood and a weaker ebb flow of longer duration. Whilst Liverpool Bay displays the presence of sea bed drift towards the coast, surface drift occurs in a northerly direction (McDowell and O’Connor, 1977). This finding has been supported by the CETaSS sediment transport modelling (Halcrow, 2010c). Extreme sea level predictions have however, been derived for the North West England and North Wales coast as part of a number of tidal flood mapping projects. The calculated extreme sea levels for sub-cell 11a are included in Tables 4.1 and 4.2. These tables show present day estimates of extreme levels, and do not allow for sea level rise. These levels present the baseline data to which sea level rise predictions need to be applied. Water level data from the Class A gauge at Liverpool Gladstone Dock have been obtained by Sefton for the past 10 years. Quality checked data are available on a monthly basis but not until three months after the end of the month it was captured. The recorded water level data are presented in Table 4.1 Table 4.1: Summary of Annual Maxima Recorded Water Level Data 2001-2010 (Liverpool Gladstone Dock) (Sefton 2011) 2001 2002 2003 2004 2005

Maximum Reading (m OD) 5.424 5.756 4.975 5.059 5.471

Approx. Return Period of <1 3-4 <1 <1 1-2 Max. Water Level (yrs)

2006 2007 2008 2009 2010

Maximum Reading (m OD) 5.752 5.576 5.096* 5.255 5.442

Approx. Return Period of 3-4 1-2 <1 <1 1-2 Max. Water Level (yrs)

Extreme water levels have also been provided by the Environment Agency from a national scale study, those figures are presented in Table 4.2.

Table 4.2. Extreme Water levels for various sites in sub-cell 11a (m OD). From the Environment Agency study Coastal Flood Boundary Conditions for UK mainland and islands (Environment Agency, 2011). Alongshore chainage is given for each site. The Environment Agency state that values provided by this study can be considered accurate to one decimal place. Return Great Colwyn Rhyl Point of Hoylake Wallasey Formby Ainsdale Period Orme Bay Ary (years)

CHAINAGE 1106 1120 1134 1148 1154 1134 1178 1186

1 4.71 4.86 5.03 5.2 5.28 5.03 5.25 5.3

10 4.99 5.15 5.34 5.53 5.62 5.34 5.62 5.67

25 5.09 5.26 5.46 5.66 5.75 5.46 5.76 5.8

50 5.18 5.35 5.55 5.76 5.84 5.55 5.87 5.9

100 5.26 5.44 5.64 5.85 5.94 5.64 5.97 5.99

250 5.38 5.55 5.76 5.97 6.06 5.76 6.09 6.11

500 5.47 5.64 5.86 6.07 6.16 5.86 6.19 6.19

1000 5.56 5.73 5.95 6.16 6.25 5.95 6.28 6.27

10000 5.87 6.04 6.25 6.46 6.55 6.25 6.56 6.49

Sediment Transport The net sediment transport direction along the North Wales coast is eastwards. The transport rate is moderate to high for sand, but lower for shingle as a consequence of the hydrodynamic energy climate (Motyka and Brampton, 1993). The transport of sand between Liverpool Bay and the Dee and Mersey follows the residual currents within the bay. Sediment transport pathways diverge at Formby such that to the north material is transported northwards towards the Ribble estuary and to the south of the point it generally moves southwards towards the Mersey. The result is beach and dune erosion at Formby. The 2010 monitoring has reinforced the understanding of the Sefton area presented in the Baseline Report and conceptual model. The annual monitoring shows that overall there was a modest reduction in beach volumes of approximately 60,000m3 over the 12 months since the Autumn 2009 survey, with losses of approximately 280,000m3 over the winter period 2009-10 and gains of approximately 220,000m3 over the summer period in 2010. Overall, Sefton beach volumes remain approximately 2.5 million m3 greater than when topographic monitoring commenced in 2001. The change at the Sefton shoreline is very much driven by the energy impacting the shoreline particularly during storm conditions, which varies considerably year on year, induced by natural variation in conditions. However, the net gain each year is due to onshore movement of sand, likely to be by constructive waves gradually building up the shore.

Anthropogenic Modifications This coastline has experienced a number of significant anthropogenic modifications over the last few hundred years. Over the last 200 years, the construction of a mixture of seawalls, revetments, groynes and flood embankments along the majority of the North Wales coast has prevented shoreline erosion and managed flood risk to coastal towns (including Llandudno, Rhos-on-Sea, Colwyn Bay, Towyn, Rhyl and Prestatyn), tourism assets and infrastructure (railway and road). However, these structures have also led to a lowering of beach levels, erosion of dunes and the need for beach management. Consequently, a number of recharge schemes have taken place at Llandudno and along the Point of Ayr frontage to combat the trend of falling upper beach levels. Anthropogenic modifications within the Dee Estuary include past reclamation works, construction of training walls and subsequent dredging. Past reclamation has led to increased accretion rates as the estuary tidal prism has reduced and channel training has prevented channel movement and has consequently encouraged saltmarsh growth. Much of the Welsh bank of Dee estuary has industrial and commercial activities at the shoreline, including factories and power stations, as well as the railway line and roads. A number of urban areas, including West Kirby, Parkgate, Connah’s Quay and the city of Chester are also located around the estuary. The northern Wirral coastline is currently defended along the whole frontage, providing both erosion and in places flood protection to the residential settlements of Hoylake, Meols, Moreton and Wallasey, as well as a number of recreational assets. The hard coastal defences, which consist of a combination of seawalls, revetment, offshore breakwaters and rock groynes, have had the affect of fixing the existing shoreline position, preventing erosion along this coastline and the resultant roll-back of sand dunes in response to sea level rise.

The Mersey Estuary has also experienced a number of significant anthropogenic modifications over the last few hundred years, including dredging of channels for navigation purposes, construction of training walls and the Manchester Ship Canal and significant port and industrial development. Consequently, the ‘Narrows’ shoreline is now almost entirely industrialised with extensive port facilities, power stations, oil refineries and onshore wind farms. There are also substantial urban areas, with associated recreational and amenity facilities throughout the estuary. Training of the Crosby Channel, seaward of the Narrows first took place in the early 1900’s, and since that time it has been extensively dredged. Over the past two centuries material dredged from the Mersey has been dumped offshore, which, together with the training works, is believed to have contributed to siltation of the Formby Channel and the resultant reduction in sediment supply to Formby Point. The Sefton frontage supports a number of large urban settlements, namely Crosby, Hightown, Formby and Southport. Up until, the 1930s the shoreline between Bootle (north of Liverpool) and Southport was a continuous natural dune belt interrupted only at Hightown where the River Alt discharged through the hinterland onto the foreshore. Today, much of the frontage remains unprotected by defences, with structures concentrated at Crosby, Blundellsands and Southport. Although there are few man-made defences, the whole of the Sefton coastline has been affected by anthropogenic modifications. The course of the River Alt has been altered, with a training bank built in the 1930s to deflect the channel away from the shoreline and reduce local dune erosion along the Blundellsands frontage. The Formby Dune system has been modified in the past to limit erosion and stabilise the dunes. In addition, parts of the dune system have been built-on for the creation of recreational facilities, such as car parks and the Holiday Camp at Ainsdale or re-forested. Dumping of organic tobacco waste along the National Trust frontage also took place historically along this frontage. Although originally some way landward of the shoreline, this material is now becoming exposed as dune erosion has continued. There have been no changes to shoreline or defence arrangements on the Sefton frontage in 2010. There are also a number of offshore wind farms within the sub-cell area, both operational and under construction. These developments were assessed at planning stage for impacts on process behaviour both in the vicinity of the developments and along adjacent shorelines. Conceptual Understanding A summary of the conceptual understanding of coastal processes along the sub-cell 11a frontage is presented in Table 4.3 and illustrated in Figure 4.2.

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / Great Orme’s Head and Little Orme - The resistant limestone headlands are barriers to littoral transport, although there may still influencing features be some transport of sands and fines around the Little Orme due to tidal currents (Ref 1). Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d)

Sediment sources • Negligible erosion (<0.1m/yr) from the resistant limestone headlands, recession would be as a result of localised rock falls or landslips (Ref 2) • Low erosion rates from the complex of erodible till (boulder clay) sea cliffs between the headlands. There is only a short section of remaining unprotected land within the bay

Great Orme to Orme Little Great Orme to • The key source of sediment is from the reworking of sediments within the bay

• There may also be a potential feed of fine sediment from offshore (Constable Bank). A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e). Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c)

Sediment sinks / • Constable Bank (5km offshore) A review of offshore banks was carried out for CETaSS, including characteristics and processes stores (Halcrow, 2010e)

Sediment pathways / • The bay experiences a semi-closed system in terms of sediment patterns, any coarse sediment released from cliff erosion will tend dynamics to remain within the bay • Littoral sediment transport takes place predominantly from west to east, although drift reversal resulting from north to east storms does take place. Great Orme’s Head marks the western boundary. This finding was supported by the CETaSS littoral transport modelling (Halcrow, 2010d) • There may be a sub-tidal onshore-offshore exchange of sediment (fines) between Orme’s Bay and Constable Bank, dependant on weather and tidal conditions. There is potential that in some instances the amount of material moved offshore could be greater than the amount of material moved onshore. A review of offshore banks was carried out for CETaSS (Halcrow, 2010e)

Hydrodynamics • The tidal wave propagates from west to east and flood dominance results in a potential west to east movement of material. This was supported by the CETaSS regional transport modelling (Halcrow, 2010c) • Great Orme’s Head induces a clockwise eddy, which results in a small localised circulatory current cell within the western end of

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding Orme’s Bay (Ref 1) • The North Wales coast experiences a high tidal range - spring tide range is up to 7 metres and the neap tide range is over 3.5 metres • Constable Bank has a limited effect of northerly storm waves along this coast. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • The coast is vulnerable to storm surges

Beach & Shoreline • Llandudno - Beach volumes reducing, with a faster rate of lowering taking place to the western end of Orme’s Bay (Ref 3). Response

Control / • Little Orme - The resistant limestone headland is a barrier to littoral transport, although there may still be some transport of influencing features sands and fines around the headland due to tidal currents. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • Tan Penmaen - The rock headland acts as a partial barrier to upper beach drift, but allows the bypass of small amounts of fine gravel and sand across the lower beach • Rhos Point - The artificially defended cliff promontory exerts varying control on exposure conditions, coastal process behaviour and sediment transport

Little Orme to Point of Ayr to Orme Little • Llanddulas - The outlet from the Afon Dulas controlled by an artificial rock groyne exerts varying, generally local control on exposure conditions, coastal process behaviour and sediment transport • Coastal defences - Beach control breakwaters and rock groynes influence littoral transport and upper beach levels at a number of locations, including Rhos on Sea breakwater, Penrhyn Bay fishtail groynes, the training wall at Llanddulas and major groyne fields at Prestatyn. The re-construction of defences at Towyn following the 1990 storm interfered with upper beach longshore drift across this section • The Welsh Channel - This low water channel linked to the tidal regime and channel of the Dee Estuary has local influence on the stretch of coast between the River Clwyd and the Point of Ayr (Ref 4) • Offshore banks - The offshore sand banks of Constable Bank and Rhyl Flats, have an influence on the geomorphology of this coastline, through the possible exchange of sediments and potential impacts on hydrodynamics. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e)

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Sediment sources • Inputs from the till (boulder clay) cliffs and dunes (although the majority of these are currently defended) • Redistribution of glacial material (sand and shingle) eroded from the nearshore bed • Onshore movement of sediment from offshore banks (Rhyl Flats, Constable Bank) • Onshore movement of clay, silt and sand-sized sediments from Llanddulas to the Point of Ayr

Sediment sinks / • Constable Bank stores • Rhyl Flats • Point of Ayr • Dee Estuary (predominantly sink for muds and silts and some sand) • A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e)

Sediment pathways / • Alongshore sediment transport takes place in a net west to east direction along the littoral zone. Any finer sediment moved dynamics offshore from this frontage will be redistributed within the limits of Liverpool Bay. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • The ridges and runnels present along the beaches are quasi-dynamic features and can cause local issues, particularly where runnels move inland producing rapid decreases in beach level. Bars and troughs on this wide foreshore migrate slowly eastwards influencing a pattern of erosion and accretion along the foreshore • A sediment transport pathway exists between Orme’s Bay and Penrhyn Bay to the east, however, due to the presence of Little Orme’s Head, there is a very weak littoral linkage; with transport limited to sand and finer sediments (Ref 5) • Penrhyn Bay - There are large fishtail groynes controlling upper beach levels • East of Llanddulas - The shoreline lies more normal to the prevailing wind and wave direction, reducing net sediment transport rates along the frontage as far as the Clwyd Estuary • Pensarn - Net potential sediment transport is estimated to be in the region of 16,000m3 in front of the Pensarn Promenade, reducing to 4,000m3 in front of the Towyn Seawall (Ref 6) • Dulas and Clwyd Rivers - They discharge to the sea along this coast and in doing so interrupt sediment transport to a minor degree. Sand transport continues across the deltaic formation of the Clwyd as it crosses the lower foreshore • Rhyl - This shoreline is orientated away from the prevailing wind and wave direction, resulting in an increase in net sediment

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding transport • Prestatyn - The upper beach has been stabilised by the construction of large T-head rock groynes, limiting littoral drift • Point of Ayr - Upper beach sediments exhibit a net eastward movement, however, interaction between estuarial and open coastal processes result in a complex nearshore sediment circulation around the Point of Ayr (Ref 7). During storms, material can be pushed into lee of Point of Ayr spit (Ref 5) • Dee Estuary - There is a transport of sand across the mouth of the estuary from the Point of Ayr via the West Hoyle and East Hoyle Banks and there is an exchange of material into and out of the Dee Estuary. The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g)

Hydrodynamics • The North Wales coast experiences a high tidal range - spring tide range is up to 7 metres and the neap tide range is over 3.5 metres • There is a general west to east dominance in the tidal stream with residual tidal currents then turning south-east towards the Dee Estuary. This was confirmed by the regional modelling undertaken as part of the CETASS project (Halcrow, 2010c) • The offshore sand banks of Constable Bank and Rhyl Flats limit the effect of northerly storm waves along this coast. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • A reversal of currents may occur in Colwyn Bay (Ref 8), possibly caused by the construction of the Rhos-on-Sea breakwater, which results in the formation of a localised net drift reversal to the south of Rhos Point during storms • Tidal energy levels have decreased at the Point of Ayr spit in recent years due to a decrease in the tidal energy of the Welshman’s Gutter (which links Hilbre Channel and Welsh channel), resulting in a shift in tidal energy further offshore at the mouth of the Dee Estuary

Beach & Shoreline • Penrhyn Bay - Exhibits cyclic behaviour, beach levels mostly stable where beach recharge and control structures have been Response constructed. Generally stable/marginally lowering beaches between here and Rhos Point • Colwyn Bay - Profile monitoring (Aug 1995 to Nov 1999) has indicated a relative stability of the low water position within seasonal variations but beach volumes are reducing but with some cyclical variation • Afon Dulas - Material lost from west of the beach in the winter appears to have been balanced by accretion on the east side of the Afon Dulas. Cyclical movement apparent, but a net trend towards beach volume loss • East of Llanddulas Head - Upper beach erosion (1968-1988) of -0.04 to 0.14m/year (Ref 6) • Pensarn – Erosion of upper beach over western most kilometre of frontage feeding frontages with build up on updrift side of

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding Towyn sea wall. Lower sand beach is volatile • Towyn Seawall - Upper beach littoral drift which was originally interrupted by the construction of the post 1990 defences gradually re-establishing, lower beach remains volatile • Sunny Vale and Kinmel Bay Dunes - Increases in beach volume from easterly drift with some transference of material on the lower foreshore across the outlet of the Afon Clwyd (2005 - 2006) (Ref 9) • Rhyl - The foreshore immediately east of the Afon Clwyd is relatively stable but beach levels reduce in an easterly direction and the foreshore is eroding by Splash Point and across the Rhyl Golf Links frontage (Ref 10, 11) • Prestatyn - Across Ffrith and Central beaches stability to the upper beach though the lower beach sections outside the influence of the groynes remain volatile with movement of the ridge and runnel features. Material from the eroding sections to the west appears to be moved offshore beyond the groyne field and alongshore to the east • Gronant Dunes – The dunes are vulnerable to breaching with littoral drift reducing beach volumes, east of the Prestatyn groyne field. Further to the east in the vicinity of Prestatyn Gutter there is upper beach spit development and accretion. (Ref 12, 13 & 14) • East of Prestatyn Gutter - Generally this section is loosing material, with losses greater moving eastwards, although cyclical behaviour occurs. Beach recharge in 2003 between Warren and the Point of Ayr has masked natural change. (Ref 12, 13 & 14) • Point of Ayr - Foreshore volumes are decreasing as the upper beach shingle spit moves eastwards. Since monitoring began in 2002, there has been a net loss of beach volume of approximately 85,000m3 although cyclical behaviour is evident with alongshore movement of material occurring (Ref 14)

Control / • Offshore banks - (West Hoyle Spit, West Hoyle Bank, East Hoyle Spit and East Hoyle Bank) at the mouth of the Dee Estuary - influencing features provide a high degree of protection to their lee against waves generated in Liverpool Bay; this affects both the Dee Estuary shores and the open coast either side. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) Dee Estuary • Dee Estuary - The estuary interaction extends westwards to the outlet of the Afon Clwyd and eastwards to the River Mersey. The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g) • Hilbre Islands - Islands locally influence tidal propagation by restricting easterly migration of the Hilbre Channel and provide protection to the leeward inshore area from predominantly westerly waves (influence on open coast) (influence on • Welsh Channel and Hilbre Channel - Deep water channels separated by the West Hoyle Bank influence hydrodynamic conditions

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Sediment sources • The estuary receives sediment from erosion of beaches and sub-tidal profile along the North Wales coast and from offshore. The CETASS project made an assessment of estuaries throughout the Cell 11 region, including the Dee (Halcrow, 2010f, 2010g)

Sediment sinks / • Dee Estuary - large sink for predominantly muds and silts and some sand. This was confirmed by (Halcrow, 2010g) stores • Offshore banks (West Hoyle Spit, West Hoyle Bank, East Hoyle Spit and East Hoyle Bank

Sediment pathways / • Net alongshore drift is from west to east across the mouth dynamics • Although the Dee Estuary acts as a large sink there is still sand transport across the mouth via West Hoyle Bank and East Hoyle Spit. • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d)

Hydrodynamics • The Dee Estuary is macrotidal, mean spring and mean neap tidal ranges at Hilbre Island being 7.6m and 4.1m, respectively • Flows entering the estuary preferentially use the Hilbre Channel rather than the Welsh Channel • Hilbre Channel development has been hindered as Hilbre Island has restricted migration of the channel eastward resulting in the development of Welshman’s Gut and the Mid-Hoyle Channel (Ref 27). Therefore, at present, the Welsh Channel and the Mid- Hoyle Channels are dominant at the expense of the Hilbre Channel

Beach & Shoreline • West Kirby - Restriction of the Hilbre Channel has resulted in accretion of the intertidal zone between the islands and the Response foreshore is becoming vegetated (Ref 17)

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Hilbre Islands - Islands act as natural breakwaters to incoming waves influencing features • Hilbre Point and Red Rocks - The sandstone hard points exert varying control on exposure conditions, coastal process behaviour and sediment transport • Perch Rock - The sandstone hard point reinforced with beach control structures exerts varying control on exposure conditions, North Wirral coastal process behaviour and sediment transport • Dee Estuary - Influences nearshore processes to Leasowe Lighthouse along the Wallasey Embankment frontage (Ref 7) • Mersey Estuary & training walls - Influences the nearshore east end of the frontage (Ref 7) • West and East Hoyle Banks (mouth of the Dee) - Their influence extends to Leasowe Lighthouse along the Wallasey Embankment frontage, and provide protection against waves • Great Burbo Bank - Provides a high degree of protection against the waves generated in Liverpool Bay • Meols Channel - Influences shoreline processes, has generally moved in a easterly direction over time

Sediment sources • Sediment is largely supplied to this frontage via littoral drift from the North Wales coastline. CETaSS undertook littoral transport modelling (Halcrow, 2010d) • Growth of the East Hoyle Bank in an eastward direction has pushed the Meols low water channel landwards, resulting in the potential for greater erosion along the central section of the coast (Wallasey Embankment)

Sediment sinks / • Dee Estuary - Is a sink for muds, silts and some sand stores • Mersey Estuary - Acts as a sink for material lost from the Wirral frontage via easterly transport • The CETASS project made an assessment of estuaries throughout the Cell 11 region, including the Dee and the Mersey (Halcrow, 2010f, 2010g) • East Hoyle Bank - A store/ temporary sink for sediment

Sediment pathways / • Sediment is transported from west to east along the coastline. The CETASS project made an assessment of littoral transport along dynamics this stretch of coast (Halcrow, 2010d) • Alongshore sediment transport takes place in the nearshore zone, primarily on the lower beach; contemporary coastal defence measures have reduced the drift taking place on the upper beach. CETaSS undertook littoral transport modelling (Halcrow, 2010d). • Significant beach control structures provide local control on the upper beach - Leasowe breakwaters, Harrison Groyne, Kings Parade, Perch Rock

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding • The volume of alongshore sediment transport is reduced by the presence of East Hoyle Bank which is growing • The Dee Estuary is a sediment sink, however, there is still some wave-induced current transport of sediment across the mouth via West Hoyle and East Hoyle sand banks • Littoral drift does not continue across the mouth of the Mersey Estuary due to the complicated interaction of waves and strong tidal currents and the training walls • Wind blown sand is a problem at the west end of the frontage and sand mesh is used in various locations to reduce the volume of sand deposited on North Parade • Strong tidal currents swirl around Hilbre Point, transporting sediment from East Hoyle Bank to the upper beaches at Hoylake and West Kirby (Ref 16)

Hydrodynamics • Within the Irish Sea Basin, there is a near bed residual current towards the coast, which turns south-east towards the Dee and Mersey Estuaries. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). • Offshore banks (West and East Hoyle Bank and Burbo Bank) provide a high degree of protection against the waves generated in the Bay. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • The western end of this frontage is protected by the hard sand stone rock outcrop at Hilbre Islands, which acts as a natural breakwater to incoming westerly waves

Beach & Shoreline • North Wirral coastline - There is a general stable/ accreting beach. Overall beach volumes have increased by over 7 million m3 Response in the past twenty years (Ref 18), largely due to the construction of primary beach control structures • Meols Parade - The coastline is reported to have been accreting at a rapid rate over the last 20 years (Ref 17) • Leasowe Bay - The beaches have accreted following the construction of defences and have now reached a state of equilibrium (Ref 17) • Harrison Drive to Perch Rock - Following the implementation of a beach stabilisation scheme, the coastline has accreted (Ref 17)

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Mersey Estuary & training walls - The influence of the estuary and associated training walls extends towards Formby Point influencing features along the Sefton coast to the north and towards Dove Point, Meols to the west (Ref 28), Training walls have contributed to shoaling in the Formby Channel, deepening of the Queen’s Channel and growth of Taylor’s Bank (Ref 24). Dumping of dredge spoil also led to the development of Jordan’s Spit. The net effect of these works appears to have been an increase in wave focussing onto Formby Point (Ref 29). Estuary Morphodynamics was investigated during the CETaSS project, including morphology, processes, past Mersey Estuary evolution, sediment supply and future behaviours (Halcrow, 2010 f and g) • Offshore Banks - (Tailor’s Bank, Formby Bank) Further growth could increase the protection afforded to the Altcar frontage, but may increase wave focusing onto Formby Point. A review of offshore banks was carried out for CETaSS, including characteristics

(influence on open coast) on open (influence and processes (Halcrow, 2010e)

Sediment sources • Offshore Banks (Taylor’s Bank, Formby Bank, Jordan’s Spit, Great Burbo Bank). (Halcrow, 2010e) Sediment sinks / • Mersey Estuary - Is a major sink for sediments lost from the North Wirral frontage. The CETASS project made an assessment stores of estuaries throughout the Cell 11 region, including the Mersey (Halcrow, 2010f, 2010g)

• Offshore Banks (Taylor’s Bank, Formby Bank, Jordan’s Spit, Great Burbo Bank). (Halcrow, 2010e)

Sediment pathways / • The net sediment transport direction along from the neighbouring North Wirral coast is generally eastwards. The CETASS project dynamics made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d). The CETASS project also carried out regional tidal and sediment modelling including offshore dynamics (Halcrow, 2010c)

Hydrodynamics • In the future, further growth in Taylor’s Bank and Formby Bank may increase wave focusing onto Formby Point Beach & Shoreline • Material moved into the estuary can find its way onto the beaches between Seacombe and New Brighton Response

Control / • River Alt Channel and training walls - Act to curtail the southward progression of Formby Bank and redirects drift offshore influencing features • Mersey Channel training walls - Potentially prevent some of the sediment drift offshore from moving eastwards reducing Sefton sediment supply to Formby Point. The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g) • Offshore Banks (Jordan’s Spit, Taylor’s Bank, Horse Bank) - Influence inshore wave conditions (Halcrow, 2010e) • Crosby Channel - Influences inshore wave conditions

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Sediment sources • Crosby & Blundellsands - The foreshore is not covered on all tides, therefore there is potential for aeolian transport, which accumulates at the toe of the defence or is blown onto the promenade at Waterloo • Sand from Jordan’s Spit is moved onshore to the south of Formby • Along much of the frontage the frontal dunes are active, and as the dunes along the Formby frontage erode sand is released to the beach system. CETaSS undertook littoral transport modelling (Halcrow, 2010d) • At Southport there is onshore movement of fine sediment from the offshore banks

Sediment sinks / • Offshore banks (Jordan’s Spit, Taylor’s Bank & Spit, Horse Bank) (Halcrow, 2010e) stores • Infilling of the Formby Channel suggests that it is presently acting as a sediment sink or store • Formby Dune system (either side of the Point)

Sediment pathways / • Crosby & Blundellsands - The net littoral sediment transport is to the south, but the protrusion of the Seaforth Terminal dynamics effectively forms a barrier to littoral drift (Ref 19, 20) • Blundellsands to River Alt - Sediment movement along this frontage is complex, with interactions with the offshore banks. There is a potential onshore movement of sand from the offshore, although much of this sediment is believed to remain in the nearshore, resulting in the growth of Formby Bank. Movement of sand from this bank either through wave or aeolian transport is hindered by the position of the River Alt, which effectively cuts off this stretch of shoreline. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). • Although the River Alt affects the transport of sediment along the upper beach south to the beaches of Crosby and Blundellsands, sand transport is still able to take place along the lower foreshore (Ref 20) • There is a possible local drift reversal in the vicinity of the Alt mouth (Ref 21) • There is strong evidence of a net landward movement of sand from the offshore, due to residual currents, which is supported by the growth of Taylor’s Spit and Formby Banks and the infilling of the relict Formby Channel. This observation is supported by the Regional tidal and sediment modelling, which was carried out as part of CETaSS (Halcrow, 2010c) • A littoral drift divide occurs in the vicinity of Victoria Road, Formby Point, probably associated with the sediment circulation cells of the Ribble and Mersey Estuaries, with net movement of sand away from Formby Point to feed areas to both the north and south of the Point. The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • Sediment transport along the intertidal ridges is evident, and from Formby fine sand is transported northwards onto the offshore banks, such as Horse Bank which lies to the south of the Ribble Estuary

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding

Hydrodynamics • The coast is macro-tidal, with a mean spring range of around 9m at Formby Point • The eastern Irish Sea is characterised by strong tidal currents and, due to higher flood than ebb tidal current velocities, there is a near bed residual current circulation towards the coast throughout the area, turning south-east towards the Dee and Mersey estuaries and north-east towards the Ribble. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • The flood tidal streams flow landwards and then diverge around Formby Point and flow towards the Mersey and Ribble Estuaries • Surface current flow is eastward off the North Wales coast and northwards off the Lancashire coast • The coastline is susceptible to storm surges because of the shallow nature of the eastern Irish Sea and large tidal ranges • Blundellsands to River Alt - Waves from the west and west-north-west are refracted as they approach the shore. Added to this, surge conditions create deeper water over these shallows and thus large changes in the shoreline wave conditions occur during such events • Formby Dunes - Inshore wave conditions along this shoreline are significantly affected by the shallow nearshore bathymetry, including Taylor’s Bank and the Crosby Channel • Waves from the west and west-north-west are refracted as they approach the shore, with a focusing of waves onto Formby Point, resulting in an increase in breaker heights (Ref 23, 24) • Conversely there is a dispersion of waves and therefore reduced wave breaker heights between Birkdale and Southport • When total water levels exceed around 5.2m OD the impact of higher water levels against the toe of the Formby dunes results in dune slumping, adding to the effects of wave impact and undercutting (Ref 25)

Beach & Shoreline • Crosby & Blundellsands - Accretion of the beach with cyclical behaviour Response • Hall Road West to the River Alt - Analysis from historical aerial photos reviewed during the SMP2 development suggests that the frontage is experiencing erosion at an average rate of between 0.3 and 1.0m per annum. Generally stable conditions at Hightown. Formby bank growing • River Alt to Alexandra Road - accretion of the dunes and foreshore is taking place, although during storm events substantial cut back of the dunes can occur. Despite these events there is a long term accretion trend, with dune advance averaging between 0.7 and 2.4m/year (Ref 25) • Formby Point - experiencing a progressive trend of erosion along the central stretch of coast. The southern limit of erosion has remained roughly stable, but the northern limit has gradually extended northwards (Ref 24). Erosion along this central section

Table 4.3 Sub-Cell 11a - Supporting information for Conceptual Understanding Location Conceptual Understanding (between Lifeboat Road and Ainsdale) averages between 1.2 and 3.7m/year (Ref 25) • Ainsdale to Birkdale - There has been saltmarsh development known as ‘Smiths Slack’. Surveys suggest that there has been general growth in the lateral extent of the Smith Slack saltmarsh, although there is uncertainty regarding different interpretations of the marsh edge location (Ref 30) • Ainsdale to Southport - accretion is the long-term trend. Since the 1980s the average long term trend has been between -0.5 to 2.8m/year, with the rate of accretion increasing in a northward direction (Ref 21, 25)

4.2.3 Issues and Uncertainties Uncertainties in the present regional understanding of the Sub-cell 11a region have been assessed within the following strategic studies and plans:

• The first round SMP (Shoreline Management Partnership, 1999a);

• SMP 2 (Halcrow, 2009a);

• Futurecoast (Halcrow, 2002);

• A stakeholder workshop held during Phase 1 of the CETASS stage 1 studies;

• The CETaSS studies;

• The JPS; and,

• The Environment Agency’s 2011 study: coastal flood boundary conditions for UK mainland and islands.

Details of the key issues and uncertainties and where information can be found to support improved understanding of the issues and uncertainties associated with sub cell 11a are provided in Appendix A.

Only the report on the 2010 monitoring for the Sefton Frontage was made available. As a result, the findings on coastal evolution and dynamics during 2010 on the other frontages have not been used to update this report. The CETASS studies, as well the regional and Council Reports, have addressed some of the uncertainties that were identified in the original CERMS Baseline Report (Halcrow, 2010a), notably: • The existence of a drift divide at Formby Point; Erosion of Formby Point. This was investigated to a degree in the CETaSS regional tidal and sediment modelling (Halcrow, 2010c) and the results are summarised in the final CETASS report (Halcrow, 201b). However, a more detailed local model would be required to investigate the combination of littoral and tidal transport at Sefton.

However, the following uncertainties remain: • On/offshore movement of sediment in Orme’s Bay, Llandudno – 3D beach plan surveys are identifying longshore and on-offshore movement. • Potential need for future beach recharge along the North Wales coastline - Topographic beach surveys providing data to support overall beach change. • Reinstatement of drift following intervention along the Towyn embankment –physical surveys and visual observations providing qualitative and quantitative data. • Role of the ridge and runnel system (North Wales and Sefton coasts) – changes in the features identified from 2D profile and 3D plan surveys. • Influence of Talacre dunes erosion/accretion on sediment transport behaviour – Topographic Beach and Dune Surveys and LiDAR data collected are providing data to address this uncertainty. • Accretion rates along the Wirral frontage – changes quantified from analysis of beach monitoring data. This requires a combination of topographic surveys and LiDAR to provide a complete picture of change. • Shoreline exposure changes to be expected with the ongoing retreat of Formby Point – changes quantified from analysis of beach and dune toe monitoring data. • Accretion rates along the Crosby frontage – changes quantified from analysis of beach monitoring data.

4.2.4 Interpretation of Existing Monitoring Data

Interpretation of existing monitoring data is available from local monitoring reports produced for the area. The key points arising from examination of available data are summarised below for various sections of frontage within the sub cell:

Great Orme’s Head to River Clwyd (Not updated in 2010 annual review)

• Generally the upper beach deposits comprise shingle and cobble deposits, whilst the lower beaches are formed primarily of sand.

• There is generally a net west to east drift of sediment taking place across this frontage although drift reversals do take place notably in Llandudno North Shore and Colwyn Bay.

• On/offshore as well as longshore movement has been detected in Llandudno North Shore.

• Overall there have been losses of the order of 40,000m3 from the Colwyn Bay frontage since 2001.

• Across the majority of the frontages neutral behaviour at best, and reductions in volume at worst, have been observed, albeit with cyclical behaviour year on year. At the eastern end of the frontage (Kinmel Bay) upper beach drift is partially stopped by the outlet of the Afon Clwyd, although sand transport occurs across the lower beach.

• Storms surveys indicate that significant volumes of material are in motion at these times.

• From Pensarn eastwards the lower beach is characterised by ridge/runnel features. Movement of these features is transient and lower beach movement is consequently volatile.

• Construction of the Towyn sea wall in the early 1990’s provided a partial barrier to upper beach drift, with material that is moved along the Pensarn frontage being trapped by the new structure. Some drift occurs along the toe of the sea wall and it has taken 10 years for the drift to reach the eastern end of the structure. Notwithstanding this the beach in front of the Towyn sea wall is exhibiting on-going lowering.

River Clwyd to Point of Ayr

• The overall net easterly drift of material has been confirmed

• The western end of the frontage is generally stable/accreting.

• Although cyclical behaviour is taking place across the Rhyl Golf Links frontage., overall there has been a reduction in volume of approximately 60,000m3 since monitoring commenced in 2002.

• The “T” shaped rock groynes are controlling upper beach behaviour across the Ffrith Beach and Prestatyn frontages.

• The lower beach is more volatile and is characterised across the whole of the frontage by ridge/runnel features. Movement of these features is transient but their position and hence the volatility of the beach is reduced in the vicinity of the rock groynes.

• Along the western section of the Talacre Dunes frontage, although cyclical movement is taking place, the whole frontage is showing a net loss of material of nearly 50,000m3, primarily associated with the area directly east of the Prestatyn groyne field, which is losing material to the east at a greater rate than it is receiving it from the west. However further to the west the foreshore volumes are increasing due to the reverse behaviour.

• Along the eastern section of the Talacre Dunes frontage beach volumes at Talacre are higher than they were 5 years ago by virtue of the artificial recharge that was carried out in February/March 2003. However in net terms approximately 75,000m3 has been lost from the frontage over that period, it is considered likely that some of the sediment lost from the beach has moved inland to increase the height / volume of the frontal dunes, although some sediment has been moved alongshore towards the east.

• Whilst the Point of Ayr spit is extending into the estuary, beach volumes are reducing and the spit could potentially be breached by combinations of high spring tides and extreme wave conditions. During 2010 the height and volume of the dune ridge along the spit has increased, making a breach less likely.

River Dee (Not updated in 2010 annual review)

• There is a trend of accretion of the area of saltmarsh in the lee of the Point of Ayr spit.

• Generally stable foreshore conditions apply across the largely sand/mud foreshore between Llanasa and Mostyn Dock.

• The saltmarsh edge between Greenfield and Flint is eroding, primarily due to the proximity of the main Dee channel on this side of the estuary, and is in places threatening the integrity of some of the artificial defences.

• There has been generally neutral behaviour since 2002 in respect of the area of saltmarsh between Flint and Connahs Quay.

• There has been a gradual northerly spread of saltmarsh along the Wirral side of the estuary during the 20th century, which now dominates the shoreline conditions downstream to its present northerly limit at the southern end of Thurstaston Cliffs.

• The behaviour of the shoreline between West Kirby and Thurstaston is linked to the location of the Gayton channel which meanders along the frontage and provides a conduit for tidal energy to reach the shoreline. The cliffs are undefended at the southern end of the frontage and are gradually eroding. Across the northern half the cliffs are defended preventing on-going erosion. There is a weak net southerly drift across this section with upper beach volumes generally reducing.

• Between West Kirby to Red Rocks conditions are driven by the East Hoyle Bank that spans the gap between Hilbre Island and Red Rocks and minimises the direct tide and wave energies impinging on the area from Liverpool Bay. Consequently the main flood flows enter the estuary via the Hilbre channel to the west of Hilbre Island before spilling over the frontage from the south. This results in a low energy environment with beach areas fed primarily by windblown sand blown into the area from East Hoyle Bank or finer sediments transported by the low magnitude flows. This environment has resulted in the formation of green beach areas and dunes in the northern half of the frontage that have covered the artificial defences, and associated windblown sand problems.

North Wirral Coast (Not updated in 2010 annual review)

• Generally upper and middle foreshore volumes are accreting all across the North Wirral coast as a result of the easterly spread of East Hoyle Bank at the western end and the construction of breakwaters and shore connected groynes at the eastern end in the 1980s which have interrupted the longshore drift which used to end up in the Crosby channel and provided improved foreshore conditions.

• Between Red Rocks and Hoylake, the shoreline is well sheltered further offshore by the East Hoyle Bank that is fed by the westerly longshore transport across the mouth of the River Dee. Consequently wave conditions at the shoreline are limited by both the effects of the offshore bank and by the wide foreshore over which they have to travel before they reach the shoreline. Exposure conditions are low across this section with waves generally depth limited when they reach the shoreline. This has led to wind blown sand problems and vegetation growth on the beach, which is controlled by regular spraying.

• Across the Hoylake to Meols frontage, conditions are a continuation of those applying to the west with the shoreline sheltered by the eastward progression of the East Hoyle Bank, consequent low exposure conditions and high beach levels applying. Defences across this section are showing signs of ageing.

• The Wallasey Embankment frontage provides tidal flood protection to large low lying parts of the North Wirral hinterland. The spread of the East Hoyle Bank here has pushed the

discharge from the Meols channel eastwards such that it now meanders along the toe of the embankment across most of the eastern half, providing a threat to the integrity of the shoreline. The channel eventually forces its way across the beach, as the impact of East Hoyle reduces.

• The frontage between Leasowe Bay at the eastern end of Wallasey Embankment and the eastern end of the North Wirral coast is largely controlled by the breakwaters and groynes described above. • The breakwaters at Fort Perch Rock control the longshore drift of sand across the upper beach from the west. However the permeable nature of the structure and movement of material within the lower inter-tidal/immediate sub tidal zone provides sediment that can be moved into the Mersey for distribution on the Wirral beaches. This is supplemented by material brought in directly by the flows within the Mersey entrance channel.

River Mersey (Not updated in 2010 annual review)

• The River Mersey section of the Wirral is essentially sheltered from the predominant exposure directions that impact the shoreline across the North Wirral coast, with conditions becoming more benign moving upstream.

• There is a drift of material southerly along the frontage that is controlled by three rock groynes between New Brighton and Seacombe Ferry. The magnitude of drift reduces moving upstream with some by-passing of the groynes taking place. There is however generally insufficient energy to move this material to the upper parts of the beach.

• Notwithstanding the above beach volumes are improving across the New Brighton to Seacombe frontage

• Upstream of Seacombe Ferry exposure conditions are predominantly influenced by water levels

Sefton Coast

• In 2010 there was a reduction in beach volume within the limits surveyed of approximately 60,000m3, which represents a reduction in average elevation of <5mm over the whole Sefton beach area covered by the surveys. However, overall beach volumes above -5 m OD remain approximately 2.5 million m3 greater than when topographic monitoring commenced in 2001, which represents almost a 1.5% increase in volume and equates to an average increase in elevation over the whole area of about 120mm.

• The River Alt continues to provide a barrier to significant sediment movement inshore from Formby Bank, between Hightown and the Alt training bank.

• The feed of sediment southwards from Formby Bank towards Crosby and Seaforth is variable year on year with the consequence that beach volumes are cyclical across the Crosby frontage with, it is thought, some losses of sediment offshore as well as a feed to the dunes.

• Continuation of the pattern of recession/advance of the dune line .around Formby Point with cyclical behaviour observed between surveys. The dune toe line at the end of 2010 was further seaward than at the end of 2009 along the majority of the frontage.

• The primary driver for dune erosion is considered to be water level, as without high tide levels waves cannot reach the toe of the dunes. Significant dune erosion only occurs during times when high energy waves coincide with high to very high tides, and especially when mid and upper beach levels are low. As a result stoms are an important control. During 2010 the primary erosive events coincided with high spring tides but relatively mild wave conditions (<1.5 metres Hs). Had there been greater wave activity at the times of peak water level then much greater erosion would have occurred. The changes that occurred in 2010 were primarily single event driven erosion interspersed with calmer periods that allowed for dune repair to take place with the reservoirs of eroded sand on the beach being transported back into the dunes.

• Formby beaches are characterised by ridge/runnel features which lie at a slight oblique angle to the high water line. These features vary in amplitude and position over time. Monitoring has recorded their alongshore movement which results in variations in the elevation of the mid and upper beach. This in turn has an influence on the wave energy reaching the dune toe.

• All sections of the Formby dune frontage are exhibiting cyclical behaviour but the section generally between Victoria Road and Fisherman’s Path shows net long-term erosion, while the sections to either side show long-term net accretion. The location of the “hinge points” between accreting and eroding frontages is moving slightly south at the northern end, whilst remaining fairly constant at the southern end since intensive monitoring began in 2001.

• The area of green beach between Ainsdale and Southport has almost doubled between 2003 and 2009, spreading southwards as restrictions to this movement were removed.

• The CEFAS wave buoy lies offshore from this section of shoreline and identifies that the predominant wave directions are from the W to WNW sector, with annual maximum wave heights in excess of 4 metres and sometimes 5 metres. This pattern was repeated in 2010.

• Maximum recorded water levels recorded at Liverpool in the last ten years have coincided with predictions of events of annual probability of occurrence of between 10 and 100%.

4.2.5 Conclusions The update for 2010 has been based only on the report made available by Sefton Council, as reports for other areas were not available. The findings of the 2010 monitoring have supported the conceptual understanding laid out in the Baseline Report (Halcrow 2009). The regional scale modelling and studies carried out as part of the CETaSS work has clafrified the understanding set out in the Baseline Report specifically on the affects of offshore banks such as Constable Bank, tidal and littoral sediment transport and estuary dynamics of the Dee and Mersey.

4.3 Sub-Cell 11b

4.3.1 Summary Sub-Cell 11b (Figure 4.3) extends between Southport and Rossall Point. An annual update has been received from Blackpool Council which updates the overview for the Blackpool and Fylde coastlines (Blackpool 2011).

Figure 4.3 Location map of sub-cell 11b The main coastal features are: • A major estuary: the Ribble; • A smaller additional tidal river: the Douglas; • A dune system at Lytham St Annes;

• A backshore comprising defended clay cliffs at Blackpool and low-lying alluvial plains to the north and south of the town; • A foreshore composed of predominantly wide sand beaches, however, the amount of shingle increases northwards from Blackpool’s North Shore; • A scar feature at Rossall point; and, • Offshore sandbanks to the north and south of the frontage. Accretion is evident to the south of the frontage, with accretion along the Southport frontage and Lytham to Warton frontages resulting in saltmarsh growth in the upper intertidal zone and at the mouth of the Ribble in the form of sand bank development (Motyka and Brampton, 1993). Erosion, however, predominates along the Blackpool - Cleveleys beach frontage, where the beaches are actively lowering. The Fylde Peninsula only the Lytham frontage and eastern part of the Fleetwood frontage are in any sense significantly affected by estuarine processes.

4.3.2 Existing Understanding Wave and Tidal Conditions The predominant wave direction is from the north-west as is the tidal residual current. Wave action in Liverpool Bay is limited by the relatively small fetch lengths in the Irish Sea at this point due to the presence of the Isle of Man and Anglesey (Hedges et. al., 1991). The annual mean wave height is only 0.8m, but during the winter month’s significant wave heights of 5m (periods 6 to 8s) have been observed (McDowell and O'Connor, 1977). The annual 10% exceedance significant wave height is 1.0 to 2.0m. The mean tidal range is 6.6m at Blackpool. There is no new data on inshore waves from the 2010 monitoring. For .information on the 2010 offshore waves please see the sub-cell 11a section. Extreme sea level predictions have however, been derived for the North West England coast as part of a number of tidal flood mapping projects. The calculated extreme sea levels for sub-cell 11b are included in the following table (Table 4.4). This table shows present day estimates of extreme levels, and does not allow for sea level rise. The sea level information has recently been updated by the coastal flood boundary conditions report and the relevant information is presented in Table 3.1. These levels present the baseline data to which sea level rise predictions needs to be applied.

There has been an update to the understanding of extreme water level in this sub-cell during this year. The Environment Agency published an analysis of the extreme water levels for various return periods, their results for a selection of sites is presented in Table 4.4.

Table 4.4. Extreme Water levels for various sites in sub-cell 11b (mOD). From the Environment Agency study Coastal Flood Boundary Conditions for UK mainland and islands (Environment Agency, 2011). Alongshore chainage is given for each site. The Environment Agency state that values provided by this study can be considered accurate to one decimal place.

Return Southport Lytham St Blackpool Cleveleys Fleetwood Period Anne’s (years)

CHAINAGE 1194 1204 1218 1224 1232

1 5.4 5.45 5.35 5.39 5.59

10 5.8 5.85 5.73 5.77 5.98

25 5.95 6.01 5.89 5.92 6.14

50 6.07 6.13 6 6.04 6.27

100 6.17 6.24 6.12 6.15 6.39

250 6.31 6.39 6.27 6.3 6.55

500 6.41 6.51 6.38 6.41 6.68

1000 6.51 6.62 6.49 6.52 6.8

10000 6.8 6.96 6.84 6.88 7.2

Sediment Transport The Fylde coastline is considered to be relatively sediment-starved, with a net trend of erosion and beach lowering experienced along much of its length. There is potential onshore movement of fine to medium sand, although these offshore deposits overlie till and are generally less than 1.5m thick, indicating that supplies are limited and potentially relate to slow erosion of the underlying till. Whilst there is evidence of this movement there is no associated evidence of beach accretion, indicating that rates are less than, or equal to, alongshore transport rates (Halcrow, 2002). The estuary regimes bordering this frontage are considered to be sinks and so provide little sediment. According to the CETaSS modelling a littoral drift divergence occurs south of the Blackpool frontage but its position is uncertain and may not necessarily be constant. There is also a sub-tidal transport divide offshore from Blackpool. Accordingly, material is transported northwards to Fleetwood and southwards towards the Ribble. Any further southwards drift is terminated at the Ribble Estuary where the large sand banks act as sediment stores (Halcrow, 2010b). Anthropogenic Modifications The Ribble Estuary has undergone a number of anthropogenic modifications in the past, including: widespread reclamation, construction of training walls for navigation purposes, dredging and more recently, managed realignment. The low-lying land around the estuary is mostly agricultural interspersed with settlements including Southport, Hesketh, Hutton, Walmer Bridge, Penwortham, Freckleton, Warton and Lytham St Annes while the urban area of Preston lies adjacent to the upper estuary. Tourism and recreational facilities exist, including a number of sailing clubs and nature reserves. The Fylde frontage, between Lytham St Anne’s in the south and Fleetwood in the north, is heavily urbanised and dominated by the major tourist centre of Blackpool and the towns of Thornton and Cleveleys. The majority of the frontage is defended by seawalls. The walls were erected principally to combat erosion and consequently, much of the shoreline is now held seaward of its natural position, which has resulted in beach lowering as the shoreline is unable to retreat. Regular inspections of defence condition have continued for the Blackpool and Fylde .structures. Blackpool inspections were carried out in November 2010. Fylde inspections were, at the time of writing, in progress. As a result the 2010 Flyde defence report was not obtained for this update. No significant changes have been made to the coastal defences that would alter sediment transport on Sub Cell 11b coast (Blackpool 2011). Conceptual Understanding A summary of the conceptual understanding of coastal processes along the sub-cell 11b frontage is presented in Table 4.5 and illustrated in Figure 4.4.

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Ribble Estuary - changes within the estuary (dredging, land claim, training channels) have resulted in accretion and saltmarsh influencing features development along the frontage (Ref 1). Most recently, the cessation of dredging of the main low water estuary channel has enhanced the trend of shoreline accretion at Southport, by reducing ebb tidal current transport in the South Channel, located off Southport.

Southport The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g). Local scale modelling of the Ribble was also carried out as part of CETaSS (Halcrow, 2010h) • Offshore Banks - Have an influence on the geomorphology of this frontage, through the possible exchange of sediments and potential impacts on hydrodynamics. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Formby Point - Influences the position of the drift divide and supplies sediment to the Southport frontage and wider estuary

Sediment sources • Offshore Banks - Unquantified feed of sediments from offshore banks (Halcrow, 2010e) • Formby Point - Feed of sediments from erosion of Formby Point • Ribble Estuary - The River Ribble is believed to carry fine silt downstream, which settles out on the northern beaches of the Sefton coast, where there are sheltered conditions (Ref 2)

Sediment sinks / • Ribble Estuary - Is a strong sink for sediments stores • Offshore banks (Horse Bank) - stores / sinks (Halcrow, 2010e)

Sediment pathways / • Long term estimates of sediment influx suggest there is an average of 1,000,000m3/year sediment entering the Southport system (Ref dynamics 3) • There is littoral sand transport northwards along this frontage, into the Ribble Estuary. CETaSS undertook littoral transport modelling for this region(Halcrow, 2010d) • At Southport there is also onshore movement of fine sediment from the offshore banks (Halcrow, 2010e) • Fine sand is transported northwards from Formby Point onto the offshore banks, such as Horse Bank

Hydrodynamics • The coast is macro-tidal, with a mean spring range of 8m at Formby Point • The eastern Irish Sea is characterised by strong tidal currents and, due to higher flood than ebb tidal current velocities, there is a near bed residual current circulation towards the coast throughout the area, turning north-east towards the Ribble. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • The flood tidal wave propagates landwards and then diverges around Formby Point flowing towards the Mersey and Ribble Estuaries • Reduced ebb tidal current transport in the South Channel, located off Southport, has enhanced the trend of shoreline accretion at

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding Southport • The coastline is fronted by wide intertidal flats, which dissipate wave energy

Beach & Shoreline • Ainsdale to Birkdale - There has been saltmarsh development known as ‘Smiths Slack’. Surveys suggest that there has been general Response growth in the lateral extent of the Smith Slack saltmarsh, although there is uncertainty regarding different interpretations of the marsh edge location (Ref 4) • Marshside - Finer sediments have settled high up the beach, encouraging saltmarsh growth. The saltmarsh extent is extending seawards and southwards towards Southport Pier (Ref 1). There has been an associated seawards movement of the mean high water mark • Accretion has been apparent in the upper intertidal zone (including saltmarshes), with little change in volume in the lower intertidal zone (Ref 5)

Control / • Ribble Estuary - The banks and channels of the outer estuary are a key influence on the adjacent Sefton and Fylde shorelines. influencing features Growth of the offshore banks affords protection to the adjacent open coastlines, due to wave attenuation; whilst the movement of channels close to the shorelines can result in shoreline erosion. The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g). Local scale modelling of the Ribble (Halcrow, 2010h) was also carried out as part of CETaSS. • Offshore Banks (Horse Bank, Salters Bank) - Potential impacts on hydrodynamics. A review of offshore banks was carried out for Ribble Estuary CETaSS, including characteristics and processes (Halcrow, 2010e).

Sediment sources • The main sources of sediment to the Ribble are the offshore region of Liverpool Bay. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) (influence on open coast) (influence on open • Sand-sized sediment is supplied to the Ribble Estuary from the coasts to the north and south by alongshore transport (Ref 6)

Sediment sinks / • Ribble Estuary - Is a strong sink stores • Offshore banks (Horse Bank, Salters Bank) - stores / sinks (Halcrow, 2010e)

Sediment pathways / • The contribution of sediment from erosion around Formby Point to the estuary infilling is minor when compared to the total volume dynamics of material entering the estuary from the bed of the Irish Sea (Ref 7) • The estuary acts as a hydraulic barrier to the movement of sediments, hence the wide expanses of accumulated sand at either side of the river mouth, although small quantities of sediment may be transported across the river mouth. This sand may eventually feed back into the system or is transported offshore. • Sediment is transported south from Blackpool via littoral drift, however, the contribution of sediment is small compared to the influx

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding of fine sediments from the offshore. • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). Local scale modelling of the Ribble (Halcrow, 2010h) was carried out as part of CETaSS. The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d)

Hydrodynamics • The dominant onshore waves are from the north-west and south-west and the orientation of the estuary mouth is such that waves are able to propagate into the estuary; however, the presence of the sand banks helps attenuate waves • Wave action is therefore most significant in the wider outer reaches of the estuary, and less significant in the narrow more sheltered inner reaches; with ‘moderate’ levels of wave energy experienced in the mid and outer parts (Ref 8) • In the vicinity of the mouth the hydrodynamic regime is quite complex. Several circulatory cells appear to operate simultaneously (Ref 9); the first operates from south of the estuary mouth offshore, to the north; the second is an anticlockwise pattern of circulation just north of Blackpool; whilst there is a third, clockwise flow over Salters Bank (located just north of the mouth), with flow over the shallowest areas of the bank being southerly • Tidally induced flows are dominantly west to east, directly into the estuary, although this flow is separated by Salters Bank, and some is directed northwards Beach & Shoreline • Warton Marsh – there has been little change in the past 150 years (Ref 13) Response

Control / • Ribble Estuary - Evolution of this coastline is likely to be affected by changes within the estuaries, particularly the Ribble, which may influencing features affect the configuration of outer banks and main channels. The CETASS project made an assessment of estuaries throughout the Cell 11 region, including the Ribble (Halcrow, 2010g) • Offshore Banks (Salters Bank) - Offshore banks at the mouth of the Ribble Estuary influence shoreline geomorphology by attenuating wave energy and providing shelter to the frontage. Growth of Salter’s Bank affects the ebb tide discharge, forcing it to flow either into the navigation channel of the Ribble, or further north. An area of low discharge may result in increased accretion of fine Lytham St Anne’s St Lytham sediments on the Lytham St Annes frontage (Ref 3). A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Channels - Natural movements of the Ribble channel will affect the southern-facing coast from Lytham Jetty to Lytham St Anne’s. This behaviour is currently artificially influenced by the remains of the navigation training banks, whose influence may change in the future, as they are not maintained

Sediment sources • The main sources of sediment are from the eroding beaches in Blackpool to the north, and onshore sediment movement (Ref 10)

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding

Sediment sinks / • Ribble Estuary - Is a strong sink for fine sediments. This was confirmed by the CETASS project (Halcrow, 2010g) stores • Offshore banks (Salters Bank) - Stores / sinks of sand (Halcrow, 2010e) • Lytham Dunes – Provide a minor sediment store but are largely fixed by human intervention

Sediment pathways / • Sediment is transported in a net southward direction towards the Ribble Estuary, although drift along the whole of the Fylde coastline dynamics is variable. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • Volumes of onshore movement are uncertain, with much of the sediment thought to be stored on Salter’s Bank at the estuary mouth (Ref 11). Sediment transport pathways from Salters Bank were found to be south towards the estuary rather than to the beach, thus indicating that extraction would not adversely affect beach levels (Ref 3) • Patterns of sand transport across the Ribble mouth are slow and complex, with the banks acting as temporary sediment stores and some sediments being moved into the estuary mouth (Ref 11) • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). Local scale modelling of the Ribble (Halcrow, 2010h) was carried out as part of CETaSS.

Beach & Shoreline • East of Church Scar, at the western boundary of Lytham, saltmarsh vegetation has established, with significant growth between the Response 1950s and 1970s (Ref 13) • Past behaviour has been influence by channel changes e.g. training and subsequent natural closure of North channel (Ref 13) • Anecdotal evidence suggests that the beaches at Lytham are accreting • The dunes between Blackpool and St Annes have over the majority of their length been relatively stable to accreting in the past 50 years but have in places been compromised by uncontrolled human access and by the impacts of stockpiling of sand extracted from Salters Bank. The dunes remain vulnerable to extreme events but upper parts of the beach are reasonably stable (Ref 13)

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Ribble Estuary - The evolution of this coastline is likely to be affected by changes within the estuaries, particularly the Ribble, which influencing features may affect the outer banks and main channels. This was confirmed by the CETASS project (Halcrow, 2010g) • Shell Flat sand bank - Provides shelter to the north part of the frontage Blackpool Blackpool • Coastal defences - In places along this section of the coastline the defences were built seawards of the natural shoreline, thus holding it at an artificial position. The historical hard vertical defences have contributed to beach lowering by preventing landward movement. These defences also exacerbated erosion of beach sediments by reflecting the impacting waves back onto the beach, causing the sediment to be lifted into suspension and thus liable to be moved back offshore or alongshore (Ref 10). More recently constructed defences have to a degree mitigated against this

Sediment sources • The shoreline is generally sediment-starved with a net trend of erosion as sediment entering the system, primarily from offshore, is not keeping pace with that being transported alongshore to both the north and south. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d)

Sediment sinks / • The sandbanks offshore of Fleetwood are sediment stores and sinks. A review of offshore banks was carried out for CETaSS, including stores characteristics and processes (Halcrow, 2010e). • Morecambe Bay - Acts as a sink for fine sediments. The status of Morecambe Bay was investigated further in Halcrow (2010j) • Ribble Estuary - Is a strong sink for fine sediments. This was confirmed by the CETASS project (Halcrow, 2010g)

Sediment pathways / • Whilst there is evidence of onshore movement of sediment there is no associated evidence of beach accretion, indicating that rates dynamics are less than, or equal to, alongshore transport rates (Ref 11) • Longshore drift is wave driven and therefore directions and rates are variable, dependent on short-term dominant conditions (Ref 12). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • A net drift divide is reported, with a variable location as a result of changing conditions. It was previously considered that on average this divide is located in the Bispham area (Ref 11), although it was recognised that it could move along the entire west-facing coastline, as the location would depend on average storm conditions over the year (Ref 3). CETaSS modelling confirms the existence of a flow divergence offshore off Blackpool. However, the littoral transport modelling demonstrates that the littoral drift divide is located to the south of Blackpool rather than at Cleveleys (Halcrow, 2010d). • Rates of sediment transport, as derived from beach profile monitoring data, are about 80,000m³ per annum (Ref 10)

Hydrodynamics • There are residual circulatory tidal currents offshore, linked with the Ribble Estuary to the south and Morecambe Bay to the north, the flow diverging offshore of the Blackpool frontage. Regional tidal and sediment modelling was carried out as part of CETaSS

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding including offshore dynamics (Halcrow, 2010c). • Tidal currents travel east to west at the southern end of the frontage, and north-east to south-west at the northern end, offshore of Fleetwood (Ref 10)

Beach & Shoreline • Blackpool beach is showing a slow trend of erosion with variable beach levels, but with a general trend of beach lowering. Figures Response indicate losses of the order of 2,000,000m3 over the past fifty years (Ref 13)

Control / • Rossall School to Larkholme Estate - The headland provides shelter to adjacent areas influencing features • Rossall Scar - Exerts varying control on exposure conditions, coastal process behaviour and sediment transport • Shell Flat sand bank - Provides shelter to the frontage (Halcrow, 2010e) Cleveleys • Coastal defences - Beach groynes influence littoral transport and upper beach levels • Morecambe Bay - The Cleveleys frontage could be influenced by large scale changes within the Morecambe Bay system

Sediment sources • Blackpool frontage - There is a net feed of sediment moving northwards into this area from the eroding beaches on the Blackpool frontage (Ref 11). • There is an onshore feed of sediments from offshore • The CETASS project made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d). Regional tidal and sediment modelling was also carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The results from this work were summarised in the main CETASS report (Halcrow, 2010b).

Sediment sinks / • The sandbanks offshore of Cleveleys i.e. Shell Flats are sediment stores and sinks (Halcrow, 2010e) stores • Morecambe Bay - Acts as a sink for fine sediments. The status of Morecambe Bay was investigated further in Halcrow (2010j)

Sediment pathways / • Drift rates from the Blackpool frontage are moderate and variable, dependent on changes in wind and wave conditions. Potential dynamics transport rates of <10,000m³ per year have been suggested (Ref 10). The CETASS project made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d). • Sediment continues to move northwards around Rossall Point, including shingle from the scar which feeds patches of cobbles on the northern facing coast Previous understanding for this stretch of coast suggested the presence of two littoral divides located at Cleveleys and around Blackpool. The littoral transport modelling undertaken for this study (Halcrow, 2010d) has modified this understanding in two ways. Firstly the littoral divide believed to be located around Blackpool is actually located a considerable way further south. Secondly there is no littoral divide at

Table 4.5 Sub-Cell 11b - Supporting information for Conceptual Understanding Location Conceptual Understanding Cleveleys, although this area has a negative sediment budget. The results from this work were summarised in the main CETASS report (Halcrow, 2010b).

Hydrodynamics • There are residual circulatory currents offshore, linked with the Ribble Estuary to the south and Morecambe Bay to the north, the flow diverging offshore of the Blackpool frontage • Tidal currents travel north-east to south-west at the northern end, offshore of Fleetwood (Ref 10). • Regional tidal and sediment modelling was also carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c).

Beach & Shoreline • Cleveleys to Fleetwood - Beach levels are extremely volatile; beach levels are known to fluctuate by up to 4 metres on a single tide Response (Ref 12), however, in general the shoreline is stable with small losses and gains confined within the area • Rossall School to Larkholme Estate - The controlling influence of the Rossall Point headland on shoreline orientation has resulted in higher beach levels on adjacent frontages (Ref 12)

4.3.3 Issues and Uncertainties Uncertainties in the present regional understanding of the Sub-cell 11b region have been assessed within the following strategic studies and plans:

• The first round SMP (Shoreline Management Partnership, 1999b);

• SMP 2 (Halcrow, 2009a);

• Futurecoast (Halcrow, 2002);

• A stakeholder workshop held during Phase 1 of the CETASS stage 1 studies;

• The CETaSS studies;

• JPS study; and,

• The Environment Agency’s 2011 study: coastal flood boundary conditions for UK mainland and islands.

Details of the key issues and uncertainties and where information can be found to support improved understanding of the issues and uncertainties associated with sub cell 11b are provided in Appendix A. The reports for the 2010 monitoring for Sefton, Flyde, Blackpool and Wyre frontages were made available. As a result there was good coverage for the Cell 11b coast.

The CETASS studies, as well the regional and Council Reports, have addressed some of the uncertainties that were identified in the original CERMS Baseline Report (Halcrow, 2010a), notably: • Existence of a littoral drift divide in the region of Cleveleys. This was investigated in the CETaSS regional tidal and sediment modelling (Halcrow, 2010c) and littoral transport modelling (Halcrow, 2010d) and the results are summarised in the final CETASS report (Halcrow, 201b). This showed that that there is no drift divide at Cleveleys although the area has a negative sediment budget and is prone to erosion.

• The collection of sediment particle size data across the sub cell has provided data to assess potential sediment movement behaviour for correlation with recorded surveys and consequent improvement of conceptual understanding of process behaviour (Halcrow, 2010d). • Impacts of managed realignment – Beach survey, LiDAR and aerial photography support examination of change associated with schemes. • The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010g) including the potential impacts of managed realignment.

However, the following uncertainties remain: • Role of the ridge and runnel system (Sefton and Blackpool/Wyre coasts) – changes in the features identified from 2D profile and 3D plan surveys. • Impact of sand mining at Salter’s Bank – Beach survey and LiDAR data providing information to identify changes within and remote from the area. A summary of existing understanding was provided in Halcrow (2010b).

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• Dune behaviour (erosion / accretion) – Defined from examination of beach survey information. • Impact of coastal structures – Beach changes resulting from new more hydraulically efficient structures supported by examination of nearshore beach change from surveys and visual observations during inspections.

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4.3.4 Interpretation of Existing Monitoring Data

Interpretation of existing monitoring data is available from local monitoring reports produced for the area. The key points arising from examination of available data are summarised below in general and, where applicable, for various sections of frontage within the sub cell:

General

• The shoreline across the majority of the frontage is artificially defended by concrete sea walls, revetments or flood banks, apart from the natural dune frontages between Starr Gate and St Annes Pier and at Fairhaven and the natural earth cliffs between Warton and the Naze Point.

• Predominant incident wave climates are from the sector south west to north west, with inshore the predominant and highest waves are from WSW to WNW.

• Within the Ribble Estuary wave conditions become less important moving upstream and still water levels dictate exposure conditions.

• Recorded wave data is available from the CEFAS WaveNet site in Liverpool Bay although this is not directly representative of conditions applying across the sub cell. Modelled wave climate information is available from a location off the mouth of the Ribble Estuary. Data from the new WaveNet III model were obtained for the Flyde and Blackpool Annual Reports and the modelled datasets from the JPS finish in 2008.

• Quality assured recorded tide level data is available for Liverpool (POL) and Fleetwood (Environment Agency). Locally a gauge is located on the North Pier at Blackpool but the datum for the gauge is unknown and the readings must be treated with caution. Additionally, problems with data recording have meant that there have been no updated data available for the Flyde and Blackpool Annual Reports since the Baseline Report (Halcrow, 2010a).

• Generally, the foreshore comprises predominantly fine to medium grained sand but locally shingle deposits occur on the upper beach, particularly along the northern part of the Starr Hill Dunes frontage, in front of the Fairhaven Dunes and between Bispham and Cleveleys.

• Moving into the Ribble estuary, as the energy levels at the shoreline reduce, finer sediments have settled out. Parts of the upper intertidal zone have been colonised by saltmarsh which increased in extent considerably between the 1950s and 1970s but appears to have slowed down more recently.

• The lower beaches, particularly along the open coast between St Annes and Cleveleys are characterised by ridge and runnel features.

Southport

• There has been an increase in beach volume of about 400,000m3 from 2001-2010 over the upper parts of the beach (typically above 2m AOD contour). Within this overall accretionary trend there is cyclical behaviour.

• The green beach at Crossens is spreading gradually southwards, with the total area south of the River Crossens outlet approximately 1,000,000m2 greater in 2010 than in 2002.

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Ribble Estuary (Crossens/Lytham to River Douglas)

• The contemporary cross sections across the marsh show only minor difference in level (typically 4.2-4.6m AOD) and little obvious change in the location of the seaward edge.

Lytham St Annes

• No specific monitoring results are available, at present, to indicate change in this section.

Blackpool

• Analysis of the monitoring data has shown that, generally, all sections of the Blackpool frontage have historically and are contemporarily reducing in volume, with .approximately 2,000,000m3 of material having been lost from the beach ., generally above -1.0m AOD, over the past fifty years. This equates to an average reduction in elevation across the entire area of about 700mm. These figures must be treated as an indication only, subject to significant uncertainty, as they are based on profiles that are typically of the order of 500 metres apart.

• Generally the trends in beach loss over the past 5-11 years are greater than the 40 year historical trends, with a reduction in volume of approximately 400,000m3 between 1997 and 2010. Different methods of data capture could account for some of the difference, as well as natural variation.

• The annual average trend for the whole frontage from 1997 to 2010 shows a loss of approximately 31,000m3 per annum.

• Within this overall erosional trend there is evidence of cyclical behaviour across all sections of the frontage.

• There is significant seasonal difference in beach movement year on year and consequently from season to season across the frontage.

• The central section of frontage between the north and south piers is eroding less whilst the flank sections to either side are seeing greater reductions in beach volume.

• The section of frontage between North Pier and Bispham is identified as being the most volatile in terms of volumes of sediment in motion.

• Overall there are greater volumes of material being moved away from the upper beach at Blackpool than are being moved into the area by natural process behaviour.

Cleveleys

The 2010 Beach Monitoring Report for the Wyre frontage has been made available by Wyre Council. The main conclusions for this frontage were that:

• the profiles at Cleveleys, to the very south of the frontage have shown an accretionary trend on the upper beach, but the mid-lower beach is eroding. This southern section of the Fylde Peninsula also saw steepening in the upper and lower beach profile and the greatest movement of the MLWN contour; elsewhere there was very little contour movement or change to the beach profile gradient.

• between Cleveleys to Rossall Point, the beaches have eroded. Sand content of the upper and middle beaches reduces towards Rossall Point and gravel content increases.

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4.3.5 Conclusions The monitoring data obtained in 2010 for the Blackpool and. Fylde frontages support the understanding presented in the .Baseline .Report (Halcrow 2009). Generally, the monitoring results support the overall conceptual model that has been previously proposed for the frontage, but volumes of sediment in motion vary considerably year on year and seasonally. Minor updates to the conceptual model diagram have been made to reflect the final findings from CETaSS. Previous understanding for this sub-cell suggested the presence of two littoral divides located at Cleveleys and around Blackpool. The littoral transport modelling undertaken for this study (Halcrow, 2010d) has modified this understanding in two ways. Firstly the littoral divide believed to be located around Blackpool is actually located a considerable way further south. Secondly there is no littoral divide at Cleveleys, although this area has a negative sediment budget. The understanding of the dynamics of the Ribble Estuary has also been improved thanks to local scale modelling.

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4.4 Sub Cell 11 C

4.4.1 Summary Sub-Cell 11c (Figure 4.5) includes Morecambe Bay and extends between Rossall Point and Hodbarrow Point, Haverigg. Reports on the 2010 monitoring were carried out for the Wyre, Morecambe and Barrow areas.

Figure 4.5 Location map of sub-cell 11c The main coastal features are: • Five major estuaries: the Wyre, Lune, Kent, Leven and the Duddon; • Two smaller river systems: the Cocker and the Keer;

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• Lune Bay: predominantly low-lying hinterland fronted by saltmarsh and a wide sandy intertidal zone; • North Morecambe Bay: undulating lowlands interspersed by resistant headlands, fronted by areas of saltmarsh, fringing narrow shingle beaches, scars and a continuous area of intertidal sandflats, mudflats and dynamic channels; • Walney Island: eroding small cliffs separated by the low-lying land and two sand and shingle spit features to the north and south, fronted by a shingle upper beach and sand lower beach, with numerous shingle and cobble scars; • Piel, Roa Islands and Foulney Islands; and, • Dune system at Sandscale Hawes. An important sub-aqueous feature of this area is the Lune Deep, a sub-tidal channel which runs between the inflowing rivers and the outer reaches of Morecambe Bay. It is a steep-sided isolated depression or channel which has an average depth of 40m, a maximum depth of approximately 80m (Wyre Boat Angling Club, 2001) and is subject to strong tidal currents. Morecambe Bay as a whole acts as a sink for sand and silt material. The local estuaries within Morecambe Bay, and their flows, strongly influence the characteristic shifting banks and channels and consequently erosion and accretion patterns along the Bay shorelines.

4.4.2 Existing Understanding Wave and Tidal Conditions

The dominant offshore waves originate from the south-west, coinciding with both the direction of the prevailing winds and maximum fetch. The annual 10% exceedance significant wave height is 1.5 to 2m. Wave action contributes significantly to the suspension of material (Aldridge, 1997). Lower wave energy is experienced on the upper foreshores due to intertidal widths, except in the Lune Deep channel, which typically focuses the energy towards the Heysham and Morecambe frontage (Motyka and Brampton, 1993). Storm surges are important in Morecambe Bay; where they are typically associated with very strong westerly or south-westerly winds (Motyka and Brampton, 1993). The tidal flows in this area are complex and input a significant amount of energy into the system. The mean tidal range is 6.4m at Heysham and 6.2m at Barrow. The main characteristics are summarised below: • flood dominated flow is observed: (1) in the Heysham Channel in a northwards direction, (2) around the southern tip of Walney Island and (3) along the south-east side of the Lune Deep; and, • ebb dominated flow is observed (1) in the Grange Channel, (2) on the north-west side of the Lune Deep and (3) on the Morecambe Flats. Extreme sea level predictions have however, been derived for the North West England coast as part of a number of tidal flood mapping projects. The calculated extreme sea levels for sub-cell 11c are included in the following tables (Table 4.6 and 4.7). These tables show present day estimates of extreme levels, and do not allow for sea level rise. These levels present the baseline data to which sea level rise predictions needs to be applied.

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There is anecdotal evidence that no significant storm events have occurred since the storms of February 1990 so the determination of local guidance for operations during storm events is temporarily on hold. However, no analysis of the wave and tidal data was carried out in the local annual monitoring report. Information about extreme wave heights in the mouth of Morecambe Bay is provided in Table 3.2.

New extreme water level data has been obtained from the EA’s national study into boundary conditions for the UK, which are shown for selected sites in sub cell 11c in Table 4.6.

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Table 4.6. Extreme Water levels for various sites in sub-cell 11c (mOD) (Environment Agency 2011). From the Environment Agency study Coastal Flood Boundary Conditions for UK mainland and islands (Environment Agency, 2011). Alongshore chainage is given for each site. The Environment Agency state that values provided by this study can be considered accurate to one decimal place.

Return Cockerham Morecambe Silverdale Cartmel Roa Island Walney Duddon Period Sands Island Mouth (years)

CHAINAGE 1242 1260 1272 1286 1298 1312 1324

1 5.83 6.16 6.48 6.24 5.75 5.32 5.32

10 6.24 6.59 6.93 6.69 6.14 5.68 5.69

25 6.4 6.76 7.1 6.87 6.3 5.82 5.84

50 6.52 6.9 7.22 7 6.42 5.93 5.96

100 6.64 7.03 7.35 7.13 6.53 6.03 6.07

250 6.79 7.2 7.51 7.3 6.68 6.16 6.21

500 6.9 7.33 7.63 7.43 6.79 6.26 6.32

1000 7.01 7.46 7.74 7.56 6.9 6.36 6.43

10000 7.36 7.88 8.1 7.97 7.25 6.65 6.78

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Sediment Transport Tidal currents dominate sediment transport in Morecambe Bay, with the net direction being controlled by asymmetry between the flood and ebb tides. Hence, the material is believed to be generally transported into the bay along the coastline and outwards in the centre of the bay. Local deviations from this do occur. Landward transport within the bay also occurs, depositing material onto shallow sand banks. Further landward transport occurs onto the sand flats outside Fleetwood and south of Heysham (Aldridge, 1997). There is a net drift divergence roughly mid way along the west coast of Walney Island; resulting mean longshore transport is believed to be directed south into Morecambe Bay and north into the Duddon Estuary. Appendix H of the CETaSS Report (Halcrow, 2010j) found that under the present regime the sediment budget for the inner bay is positive, with accretion along the inner coast, and limited build-up of the intertidal bank system, the outer coast is eroding, suggesting a negative sediment budget in this area. The exact balance of erosion versus accretion is unclear and the present day source/sink status of Morecambe Bay is therefore uncertain. In the inner Bay sediment transport is dominated by tidal action although estuary channel movements are also important. The central and outer parts of Morecambe Bay are also affected by strong tidal currents but wave action also plays a role. Under storm conditions, erosion of the sand and mudflats occurs in the intertidal area; under more benign conditions, the same sand and mudflats are built up by accumulation of sediments. The Lancaster City Council 2010 Report stated that the sediments in Morecambe Bay are highly mobile. The changes in channel position which cause rapid fluctuations in the Bay are recorded, by stationary monitoring positions, as changes in sediment size grading. Ordinarily, sediment grading analysis of a linear foreshore with a simple current model would give a good indication of change in beach gradient and wave energy levels, whilst allowing the progress of nourishment shortfalls and surpluses to be tracked with time . However, Morecambe Bay does not conform to a simple current model with wave energy at adjacent points varying widely due to the presence of volatile channels, and a very shallow foreshore gradient. Tidal currents which force sediment transport are also complicated, being non linear but a series of eddies created by foreshore outline and tidal / river flows. As a result complex dynamics within Morecambe Bay are not predictable by simple sediment grading analysis.

Anthropogenic Modifications The Morecambe Bay coastline is characterised by large areas of agricultural land interspersed with small villages as well as larger urban settlements such as Fleetwood, Heysham, Morecambe, Grange-over-Sands, Ulverston and Barrow-in-Furness. A number of industrial areas are located within the Bay, such as the Hillhouse Plant commercial power station (Wyre), Heysham Port and Nuclear Power Station and Barrow Port. The coastal railway is a significant feature along parts of the northern Morecambe Bay coast. The two railway viaducts at the mouths of the Kent and Leven estuaries are major features which have constrained channel movement, resulting in increased saltmarsh growth.

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Anthropogenic modifications within and around the estuaries include past reclamation works (Wyre, Kent, Duddon), mining and dumping of waste (Duddon, Keer, Leven), construction of training walls (Wyre, Lune) and subsequent dredging (Wyre, Lune). Anthropogenic modifications to the Walney Island shoreline have generally been localised over the past centuries. Defences in the form of rock revetments have been constructed intermittently along the west coast to prevent erosion and flooding. There are also a number of historical landfill sites on the eroding west coast of the island which constitute a risk of pollution if allowed to erode. For navigation purposes, training walls constrain the Walney Channel to the east of Walney Island. Channel dredging takes place for the ports of Barrow and Heysham. An analysis of the transect lines for Morecambe Bay carried out for Appendix H of the CETaSS Report (Halcrow, 2010j) indicates that coastal squeeze has not occurred on the limited number of transects analysed. Furthermore, the extent of saltmarsh in the Bay has increased over the last 100 years and the estuaries have generally shown net accretion, both of which suggest that coastal squeeze has not been a major issue. In Morecambe Bay the mobility of banks and channel plays a greater role in determining patterns of coastal erosion and accretion than sea level rise. This is likely to remain the case in the future. However, coastal structures have been built at a number of locations around Morecambe Bay and these have the potential to cause coastal squeeze in the future. Further studies are needed to evaluate the occurrence of coastal squeeze in these areas.

Conceptual Understanding A summary of the conceptual understanding of coastal processes along the sub-cell 11c frontage is presented in Table 4.8 and illustrated in Figure 4.6.

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Offshore banks (North Wharf Bank, Shell Flat) - Provides shelter to the shoreline dissipating the energy of the waves. A review influencing features of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Lune Deep - Provides protection to the beach by refracting waves away from the shoreline

Fleetwood • Wyre Estuary - acts as a hydraulic barrier to the movement of sediments, hence the wide expanses of accumulated sand at either side of the river mouths, although small quantities of sand and finer sediment may be transported across the river mouth • The CETASS project made an assessment of estuaries throughout the Cell 11 region (Halcrow, 2010f, 2010g)

Sediment sources • Cleveleys frontage - sediment is transported north-east around Rossall Point to the Fleetwood frontage CETaSS undertook littoral transport modelling for this area (Halcrow, 2010d) • Offshore banks (Halcrow, 2010e)

Sediment sinks / • Offshore banks (North Wharf Bank, Shell Flat, banks at the mouth of the Wyre) - Sediment stores and sinks stores • Morecambe Bay - Sediment sink (Halcrow, 2010j) • Wyre Estuary - Sediment sink (Halcrow, 2010g) • Fleetwood Dunes - Sediment store

Sediment pathways / • Alongshore drift is northerly around Rossall Point, then from west to east in response to the predominant wave direction towards dynamics the Wyre Estuary; potential rates in the magnitude of 20,000 to 30,000m³ are suggested (Ref 1). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • Some sediment is transported to offshore banks and from the banks to onshore. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Sediment is also transported onto the beaches from the dunes when there is an offshore wind (Ref 1), and vice versa when there are onshore winds. The dunes also supply sand to the beaches when they are eroded by extreme combinations of waves and water levels • Some alongshore transported material may be stored in the wide banks at the mouth of the River Wyre, whilst some is likely to bypass the river and be moved into Morecambe Bay. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) and showed this transport into Morecambe bay

Hydrodynamics • There are residual circulatory currents offshore linked with Morecambe Bay to the north • Tidal currents travel north-east to south-west offshore of Rossall Point (Ref 1)

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding

Beach & Shoreline • The Fleetwood frontage is accreting (Ref 1) Response • In many places, beach levels have risen significantly, particularly at the eastern end where beach levels have risen by up to 2m over the last 50 years (Ref 2)

Control / • Banks at the mouth of the estuary - Provides shelter to the shoreline dissipating the energy of the waves influencing features • Wyre Channel - influence exposure conditions along the Fleetwood and Knott End coasts • Scars (Great Knott and Black Scar) - aid in attenuating wave energy, offering some protection to the shoreline either side of the estuary mouth. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars.

Wyre Estuary Sediment sources • Morecambe Bay and the Irish Sea provide the main sources of sediment to the Wyre Estuary (Halcrow, 2010b, 2010c)

Sediment sinks / • Wyre Estuary - Acts as a sediment sink. The CETASS project made an assessment of estuaries throughout the Cell11 region stores including the Wyre (Halcrow, 2010f, 2010g) (influence on open coast) (influence on open Sediment pathways / • There is a net import of sediment into the estuary. Regional tidal and sediment modelling was carried out as part of CETaSS dynamics including offshore dynamics (Halcrow, 2010c) • Accretion on the open coast upper beaches either side of the estuary suggests there is also some cross-shore transport operating (Ref 3)

Hydrodynamics • The Wyre has a mean spring tidal range at Fleetwood of 8.3m and a neap tidal range of 4.3m • The Wyre Estuary is flood-dominant • Tidal currents in the outer estuary are typically less than 1.5m/s (Ref 1) Beach & Shoreline • Saltmarsh growth in the lower estuary, upstream of Fleetwood Response

Control / • Lune Deep - Provides protection to the beach by refracting waves away from the shoreline. Restricts sediment transport across influencing features the mouth of the bay • Rivers (River Wyre, Lune, Cocker) - Evolution of this coastline is heavily dependent on changes in the flood / ebb regime of these rivers, which affect the positions of mobile banks and channels, influencing the shorelines’ exposure to waves and currents, and to Heysham consequently control erosion and accretion patterns along the frontage • Sandbanks (Cockerham Sands, Sunderland Bank, Shoulder of Lune, North Wharf Bank) - These sand banks protect the adjacent Knott End-on-Sea End-on-Sea Knott shoreline and influence wave attenuation. A review of offshore banks was carried out for CETaSS, including characteristics and

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding processes (Halcrow, 2010e) • Scars (Hall End Skear, Plover Scar, Long Tongue, Red Nab Scar) - These larger resistant features formed from past erosion of the shoreline, act to provide localised protection to the shoreline behind them by virtue of the elevation ; however, they can also focus waves on adjacent sections of the coast. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Heysham - The headland at Heysham exerts a control on the shorelines to the north and south (as far as Sunderland Point) by constraining the landward migration of the deep water channels of the Kent, to the north, and Heysham Lake to the south. Heysham Harbour mouth acts as a barrier to intercept the net northerly drift along the frontage • Heysham Lake - The changing position of Heysham Lake and dredging within the harbour channel influence shoreline behaviour along this frontage. Changes in channel position influence the shoreline exposure to waves and currents, and consequently control erosion and accretion patterns along the frontage • Morecambe Bay - Changes in the flood / ebb regime of Morecambe Bay heavily influence the evolution of the coastline along this frontage. The CETaSS Morecambe Bay study included sediment fluxes, sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j).

Sediment sources • Offshore - The key sources of sediment are from the offshore zone within Morecambe Bay and from the Irish Sea. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • Adjacent shorelines - Coarser sediment inputs from adjacent shorelines are negligible. CETaSS undertook littoral transport modelling for these areas (Halcrow, 2010d) • Scars - Erosion of these scars releases minimal amounts of sand and shingle, which tends to stay within the frontage creating a storm strip beach at the toe of defences (Ref 4). The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Sunderland Point - Erosion of Sunderland Point cliffs provide a small, local source of material to the upper beach • River Lune – River flows move fluvially derived sediments downstream into the Bay (Halcrow, 2010j).

Sediment sinks / • Saltmarshes - Act as sediment stores stores • Sand banks - Act as sediment stores (Halcrow, 2010e) • Morecambe Bay - Acts as a major sediment sink (Halcrow, 2010j).

Sediment pathways / • Flows in the Wyre entrance channel acts as a hydraulic groyne, limiting littoral drift towards the east (Halcrow, 2010j). CETaSS dynamics undertook littoral transport modelling for this region (Halcrow, 2010d).

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Knott-End to Pilling - Littoral drift is eastward along the frontage by tidal currents, but due to the orientation of the shoreline, shelter from the offshore banks and effect of the River Wyre, littoral drift rates are low with rates decreasing towards the Lune Estuary.

• Cocker Channel - Training of the channel has resulted in reduced sediment volatility and consequently transfer of sediment northwards out of this area has reduced • Sunderland Point to Potts Corner - Littoral drift is northward along the frontage, however volumes of sediment transported along the coast are believed to be relatively small due to the attenuation of waves across the wide intertidal sand banks (Halcrow, 2010d).

• Heysham - Sediment inputs into this frontage are mainly from the south, via littoral transport northward, however volumes of drift are believed to be relatively small, especially along the upper foreshore • Heysham harbour arms act to interrupt some alongshore drift • To the north of the frontage sediment circulates in an anticlockwise direction where Heysham Lake acts as the flood channel and the Grange Channel the ebb • In general, drift rates are low, as fine material is generally moved onshore where it is deposited on beaches and saltmarshes • Material moved offshore may move into the Lune Deep and be recycled northwards or transported back out into deeper water

Hydrodynamics • Dominant waves originate from the south-west • Lower wave energy is experienced on the upper foreshores due to attenuation over wide intertidal flats, except in the Lune Deep channel, which typically focuses the energy towards the Heysham and Morecambe frontage (Ref 5) • Storm surges are important in Morecambe Bay; where they are typically associated with very strong westerly or south-westerly winds (Ref 5) • The mean tidal range is 6.4m at Heysham

Beach & Shoreline • Knott End to Pilling - Although the high water mark has moved seaward, development of saltmarsh on the upper beach has not Response increased. The area of saltmarsh present today appears to be similar to that recorded in the 1970s (Ref 4). Changes in the flood and ebb channels (position, depth and width) of the Rivers Lune and Cocker have resulted in localised erosion of the shoreline / marshes along the frontage

• Pilling and Cockerham Marshes - Net accretion across this section over the past 200 years (Ref 7) but with localised erosion. Saltmarsh area reduced by reclamation in the 1980s (Ref 6)

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Bank End to Bank Houses - Where saltmarsh development has been limited, net change along the shoreline has been negligible • Sunderland Point - Average erosion rate of between 0.5m/yr (Ref 4) and 2m/yr (Ref 6) • Sunderland Point to Potts Corner – Significant saltmarsh accretion over 2nd half of 20th century

• Potts Corner to Heysham harbour – Net landward movement of MHW over 2nd half of 20th century. (Ref 7)

Control / • Scars (Hall End Skear, Plover Scar) - The scars at the mouth of the estuary act to govern the height of waves that progress up the influencing features estuary and influences channel position. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Lune Estuary - Changes in the flood / ebb regime of the Lune will influence the evolution of adjacent coastlines. Regime changes

Lune Estuary Lune will affect the positions of mobile banks and channels and influence shoreline exposure to waves and currents and consequently erosion and accretion patterns (Halcrow, 2010g) • Sunderland Point - Sandstone outcrop constraining the mouth of the estuary thus influencing channel position • Training Walls – Constrain movement of the channel (influence on open coast) on open (influence • Plover Hill - Sandstone outcrop constraining the mouth of the estuary and influences channel position • Lune Deep - Provides protection by refracting waves away from the shoreline. Restricts sediment transport across the mouth of the bay

Sediment sources • Morecambe Bay and the Irish Sea - Provide the main sources of sediment to the Lune Estuary. The CETaSS Morecambe Bay study included sediment fluxes, sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j). • Sunderland Point - Ongoing erosion at Sunderland Point provides limited additional sediment to the Lune Estuary

Sediment sinks / • Lune Estuary - Acts as a sediment sink (Halcrow, 2010g) stores • Saltmarshes - Act as sediment stores

Sediment pathways / • Flux calculations for the Lune Estuary suggest flood transport of 2,700m3 of fine sand and 3,400m3 of coarse silt and ebb transport dynamics of 1,600m3 of very fine sand and 2,200m3 of coarse silt over an individual tide (Ref 6), confirms flood dominance and sediment sink status

Hydrodynamics • Flood dominant • Wave action is most significant in the outer estuary; however, the scars at the mouth of the estuary act to govern the height of

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding waves as they progress up the estuary and the waves are also dissipated by the intertidal flats

Beach & Shoreline • Estuary considered to be generally stable (Ref 6) Response • Overton and Glasson Marshes are generally stable/accreting but vulnerable to influences from local channel changes

Control / • Heysham - The headland at Heysham acts to constrain the migration of the Heysham Lake Channel and therefore is a significant influencing features control on shoreline evolution to the north and south • Scars - Provide localised protection to the shoreline. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Channels and Banks (River Keer, River Kent, Grange Channel, Heysham Lake Channel) - A key control on shoreline evolution • Railway - Constrains potential for saltmarsh rollback and shoreline evolution north of Carnforth • Jenny Brown’s Point & Blackstone Point - Carboniferous limestone outcrops, and key controls on shoreline evolution • Kent Estuary - The dynamic low water channels and banks exert a significant influence upon shoreline evolution both within the estuary and along adjacent shorelines. The CETASS project made an assessment of this (Halcrow, 2010b, 2010g, 2010j) Heysham to the Kent Estuary Kent to the Heysham

Sediment sources • Offshore - The majority of sediment supply is sourced from offshore and transported into the Bay during storms. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • Half Moon Bay - Erosion till cliffs within Half Moon Bay provides small localised inputs of material to the bay • The Rivers Keer and Kent - Provide fluvial sediment to the Bay system • Jenny Brown’s Point & Blackstone Point - Erosion of these cliffs provides some coarse material to local limestone shingle beaches which have formed in small bays, however erosion rates are low • Bolton-le-Sands cliffs - Provide a small amount of sediment to local beaches

Sediment sinks / • Morecambe Bay - Acts as a strong sediment sink for sand and silt. The CETaSS Morecambe Bay study included sediment fluxes, stores sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j) • Kent Estuary - Acts as a sediment sink (Halcrow, 2010g) • Saltmarshes - Act as sediment stores

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Sand banks - Act as sediment stores

Sediment pathways / • Material tends to follow a circulatory pattern within the Bay. Two main patterns of movement have been identified: anticlockwise dynamics drift movement in the outer Bay, and north-easterly drift movement within the inner Bay • It is thought that there is very limited alongshore sediment linkage with the shoreline to the south of Heysham, in part due to the promontory of Heysham Harbour. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c)

• Morecambe - A low to medium net eastward drift is evident along the Morecambe frontage

• Hest Bank to Arnside - Sediment links to adjacent frontages will be negligible due to low rates of littoral drift experienced in this area resulting from the low levels of wave energy

Hydrodynamics • Morecambe Bay has a large tidal range which can reach up to 10.5m during spring tides (Ref 4) • Due to the shallow nature of the Bay, storm surges can be significant, especially when associated with strong westerly or south- westerly winds

• Flood-dominant tidal flows are experienced in the Heysham Channel (in a northwards direction) and along the south-east side of the Lune Deep

• Ebb-dominant tidal flows are experienced in the Grange Channel, on Morecambe Flats and along the north-west side of the Lune Deep

• Heysham and Morecambe - The frontages are exposed to westerly waves focused towards the shoreline by the Lune Deep • Morecambe - The mean spring tidal range at Morecambe is 8.4m (Ref 4). The frontage is subject to high flood and ebb tidal flows crossing the foreshore as well as surges which can increase water levels for several hours during a tidal cycle (Ref 4) • Hest Bank to Arnside - In general, wave exposure will be limited to locally generated waves across the Bay and wave energies will generally be low

Beach & Shoreline • Lower Heysham - Undefended Lower Heysham cliffs have a low erosion potential of between 0.1 and 0.5m/year (Ref 7) Response • Morecambe - Beach levels appear to have stabilised (following completion of the Morecambe strategy), however, sediment accumulations appear to have shifted from coarser to finer grade sediments (Ref 8) • Hest Bank to Arnside - As a whole, the majority of the frontage has experienced a contemporary erosional trend with behaviour linked to movement of the Kent channel (Ref 13)

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Hest Bank - The frontage is relatively stable • Bolton-le-Sands - Erosion of marginally stable partly vegetated cliffs (fronted by saltmarsh) is low, between 0.1 and 0.5m/year (Ref 7) • Warton – General accretion of saltmarsh during the 2nd half of the 20th century but a reversal since the turn of the century (Ref 13) • Silverdale - Erosion of stable resistant cliffs is very low, less than 0.1m/year (Ref 7). Erosion of saltmarsh since mid 1970s (Ref 13)

Kent Estuary Kent 2010e) • Railway - The railway viaduct at Arnside constrains channel movements in this location and therefore has a significant effect on shoreline evolution in the outer estuary. The railway embankment at Grange-over Sands has held the shoreline in its current position

(influence on open coast) on open (influence • Holme Island - Influences shoreline form and restricts channel movement

Sediment sources • The majority of sediment supplied to the Kent Estuary is sourced from offshore within Morecambe Bay • Localised sediment input, from erosion of cliffs at Arnside, will only occur under extreme conditions (Ref 4) and is likely to represent only a small contribution to the estuary budget • River Kent – River flows move fluvially derived sediments downstream into the Bay

Sediment sinks / • Kent Estuary - Acts as a sediment sink (Halcrow, 2010g) stores • Saltmarshes - Act as sediment stores • Sand banks - Act as sediment stores (Halcrow, 2010g)

Sediment pathways / • Sediment is transported in a net northerly direction (Ref 4) into the estuary during storms and is deposited on banks within the dynamics estuary • There are thought to be no significant sediment links to adjacent shorelines due to the low rates of littoral drift along the frontages resulting from low levels of wave activity • Wave energies within the estuary are likely to be low and as a result there will be low rates of littoral sediment transport along the

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding estuary shorelines

Hydrodynamics • The orientation of the estuary means that it is relatively sheltered and therefore, in general, wave exposure will be limited to waves penetrating up the Kent Channel under storm conditions (Ref 4)

Beach & Shoreline • Arnside - Saltmarshes along the Arnside frontage have narrowed from 1975 to 1992 (Ref 4) Response • Grange-over-Sands - Experiencing saltmarsh accretion since the 1970s

Control / • Kent Estuary - Exerts a significant control on the adjacent shorelines within Morecambe Bay; changes in the flood / ebb regime of influencing features the River Kent will affect the channel configuration and therefore influence exposure of adjacent shorelines. • The CETaSS Morecambe Bay study included sediment fluxes, sediment sink status, influences of estuaries, bank/channel systems, future morphological responses and coastal squeeze (Halcrow, 2010j) • Leven Estuary - Exerts a significant control on the adjacent shorelines within Morecambe Bay; changes in the flood / ebb regime of the River Leven will affect the channel configuration and therefore influence exposure of adjacent shorelines Cartmel Peninsula Cartmel • Humphrey Head - A resistant Carboniferous limestone rock outcrop which acts as a control point • Leven Breakwater - Acts to direct the Leven channel toward the western shoreline • Channels and sand banks - Influences wave exposure along the shoreline

Sediment sources • The majority of sediment supplied to this frontage is sourced from offshore within Morecambe Bay. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • Localised sediment input, from erosion of Humphrey Head is negligible • Rivers Kent & Leven – River flows move fluvially derived sediments downstream into the Bay

Sediment sinks / • Morecambe Bay - Acts as a strong sediment sink for sand and silt (Halcrow, 2010j). stores • Kent Estuary - Acts as a sediment sink (Halcrow, 2010g) • Leven Estuary - Acts as a sediment sink (Halcrow, 2010g) • Saltmarshes - Act as sediment stores • Sand banks - Act as sediment stores

Sediment pathways / • Sediment sourced from offshore is transported north towards this frontage during storms dynamics • Sediment links to adjacent frontages will be negligible due to low rates of littoral drift experienced in this area (Ref 4)

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding

Hydrodynamics • This section of coast is exposed to south-westerly storm waves; however, in general, wave exposure will be limited to locally generated waves across the Bay

Beach & Shoreline • Humphrey Head - The recession potential is very low, being less than 0.1m/year (Ref 7) Response • Out Marsh - Experiencing saltmarsh erosion • Sand Gate Marsh - Experiencing saltmarsh accretion

Control / • Leven Estuary - Exerts a significant control on the adjacent shorelines within Morecambe Bay; changes in the flood / ebb regime influencing features of the River Leven will affect the channel configuration and therefore influence exposure of adjacent shorelines (Halcrow, 2010g) • Scars (Wadhead Scar) - Fix the shoreline position, provide local stability and protection to the frontage and control the proximity of the Leven channel to the shore. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of

Leven Estuary scars. • Channel and sand banks - Exert an influence on the degree of exposure of the shoreline to wave energy and control erosion and accretion patterns • Railway - The railway viaduct constrains channel movements in this location and therefore has a significant effect on shoreline (influence on open coast) on open (influence evolution in the outer estuary • Leven Breakwater - Acts to direct the Leven channel toward the western shoreline • Canal Foot - Acts as a control point in the outer estuary

Sediment sources • The majority of sediment supplied to the Leven Estuary is sourced from offshore within Morecambe Bay • Low till (boulder clay) cliffs within the outer estuary provide some sand and shingle to the littoral system, however, due to low rates of alongshore drift in this sheltered area, any sediment released will most likely be retained on local beaches • River Leven – River flows move limited fluvially derived sediments downstream into the Bay (Halcrow, 2010g)

Sediment sinks / • Leven Estuary - Acts as a sediment sink (Halcrow, 2010g) stores • Saltmarshes - Act as sediment stores • Sand banks - Act as sediment stores

Sediment pathways / • Sediment is transported in a net northerly direction into the estuary during storms and is deposited on banks within the estuary dynamics • Some material may be transported into the estuary from erosion to the south, however, this is likely to be negligible • There are thought to be no significant sediment links to adjacent shorelines due to the low rates of littoral drift along the frontages

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding resulting from low levels of wave activity

Hydrodynamics • The northerly orientation of the estuary mouth, combined with the construction of the railway viaduct and breakwater, reduces any wave penetration into the estuary

Beach & Shoreline • Outer estuary - Generally stable, cliff erosion has been relatively insignificant along the western frontage, due to the sheltered Response orientation of the shore • Sand Gate Marsh - Accretion of saltmarsh • Wadhead Hill - The partly vegetated, marginally stable cliffs have a low potential recession rate of between 0.1 and 0.5m/year (Ref 7)

Control / • Scars (Wadhead Scar, Elbow Scar, Moat Scar, Newbiggin Scar, Leonard Scar, Point of Comfort Scar, Head Scar, Concle Bank, influencing features Coup Scar, Foulney Twist, Conger Stones, Slitch Ridge, High Bottom, Barren Point Scar, Treshwood Scar) - Fix the shoreline position, provide local stability and protection to the frontage and control the proximity of channels to the shore. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Channels and sand banks - Exert an influence on the degree of exposure of the shoreline to wave energy and control erosion and accretion patterns. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e). Bardsea to Roa Island • Roa Island and Causeway - Has influenced shoreline evolution along the Rampside frontage • Walney Island - Provides some shelter from direct wave attack and restricts channel movement • Foulney Island and causeway - Provides some shelter from direct wave attack and restricts channel movement • Piel Island - Acts to restrict channel movement

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Sand banks - Act as sediment stores and sinks

Sediment pathways / • Net drift is north-eastwards into the Bay from Walney Island towards Ulverston, however, net transport rates are relatively low. dynamics • Localised sediment movement only occurs under extreme conditions (Ref 4)

Hydrodynamics • Being located adjacent to the mouth of Morecambe Bay, the shoreline is more exposed to wave attack than other parts of the Bay • Both Walney Island and Foulney Island provide some shelter from direct wave attack, to the east of the frontage and to Roa Island

Beach & Shoreline • Wadhead Hill - Erosion of marginally stable partly vegetated cliffs is low, between 0.1 and 0.5m/year (Ref 7) Response • Aldingham - Erosion of marginally stable partly vegetated cliffs is low, between 0.1 and 0.5m/year (Ref 7) • Rampside - Saltmarsh has developed in the sheltered lee of the Foulney embankment

Control / • Spits (South End Hawes, North End Hawes) - provides shelter to the inland coastline influencing features • Training walls - Constrains movement of the Walney Channel • Scars (Hilpsford Scar, White Horse Scar, Cross Dike Scar, Hillock Whins Scar, Cow Leys Scar, Bent Haw Scar, Nanny Point Scar, Tummer Hill Scar, Hollow Scar, Mill Scar, Walk Hall Scar Earnse Scar, North Hill Scar, Shope Tree Scar) - Locally the scars help fix the shoreline and provide shelter to the coast by promoting breaking of incident waves before they reach the shoreline. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Earnse Point Groyne - Is causing reduced sediment supply to the downdrift beaches by interrupting the alongshore transport, and thus depleting them, as well as possibly increasing erosion on the West Park frontage (Ref 9) • Duddon Estuary - changes in the flood / ebb regime of the River Duddon will affect channel configurations and therefore influence exposure of adjacent shorelines. The CETASS project made an assessment of estuaries throughout the Cell11 region including the Duddon (Halcrow, 2010f, 2010g). Additionally Halcrow (2010i) made a more detailed assessment of the Duddon Estuary. Walney Island and Barrow-in-Furness Island Walney • Walney Landfill Tip (south of Hillock Whins) – This has infilled the narrow neck of land that would otherwise have been vulnerable to breaching (Ref 9)

Sediment sources • Cliff erosion (Hillock Whins, Hare Hill) - Episodic sediment input from erosion from cliffs under extreme conditions provides a source of coarser material • Duddon Estuary - It is possible that the Duddon Estuary acts as a source of sediment for Walney Island and channel due to the tidal currents (Ref 7)

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding • Beaches - Sand is eroded from the beach by wave action. Strong onshore winds may also result in wind-blown sand feeding the dune system. Shingle is also moved longshore • Morecambe Bay - Another source of sediment may be from the outer parts of Morecambe Bay, with sand deposited on the southern west coast (Halcrow, 2010j).

Sediment sinks / • Spits (South End Haws and North End Haws) - Act as sediment sinks / stores stores • Saltmarsh - In the lee of Walney Island act as sediment stores and sinks

Sediment pathways / • Alongshore sediment drift rates are relatively low as the shoreline is orientated perpendicular to the dominant wave direction. dynamics CETaSS undertook littoral transport modelling (Halcrow, 2010d) • A mean annual drift divide exists in the region of Walk Haw Scar to Sandy Gap, which results in sediment transport on the exposed westerly coast of Walney Island to be from the centre of the island, north (sand) and south (sand and shingle) towards the spits. The exact location of this divide is uncertain, depending on annual storm conditions. Locations suggested include between Bent Haw and Hillock Whins (Ref 9), and at Mill Scar (Ref 4) • There maybe some onshore supply of fine sand • There is a possible sediment pathway between Walney Island and the Duddon Estuary associated with tidal flows. However, the Scarth Channel, which separates North End Haws, Walney Island, from Sandscale Haws may interrupt this pathway • Some fine sand may be moved offshore via the Walney Channel into Morecambe Bay but it is unlikely to be a significant volume (Ref 7) • The Earnse Point Groyne interrupts the alongshore transport of sediment, causing reduced sediment supply to the downdrift beaches, as well as possibly increasing erosion on the West Park frontage (Ref 9) • Some sediment may be transported offshore during severe weather, including the coarse materials from within the scars

Hydrodynamics • Flood-dominant tidal flows around the south of Walney Island • The main offshore tidal current, which is in a west to north-westerly direction offshore, splits to create a weak current travelling north, and a stronger current moving south, resulting in a drift divide (Ref 10) • West Coast Central - The shoreline in this area is virtually straight and roughly perpendicular to the dominant wave direction with the waves propagating over generally uniform shore-parallel contours (Ref 9). As a result of this there is little wave refraction and the sediment transport is cross-shore dominated with cliff erosion occurring under storm conditions • Tidal flows into and out of the Duddon Estuary are considered to be more significant than alongshore drift north in controlling the

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding shoreline at the very northern extent of Walney Island (Ref 9)

Beach & Shoreline • North End Haws - Accretion, where the intertidal zone has increased by up to 25m/year in the last half of the 19th century (Ref Response 9). However a secondary channel has now split from the main Jubilee Channel, which has started to reverse this trend • North of Earnse Point - Estimated rates of shoreline retreat 0.3m/yr (Ref 11) and between 0.2m and 0.6m/year (Ref 9) • West coast cliffs - Erosion at a rate of between 0.8 and 1.3m/yr (Ref 9) • Hilpsford Scar - Erosion, where approximately 20 to 30 hectares of material has been removed from this area in the past 150 years (Ref 4) • South End Haws - Accretion of the end of the spit, of 75m between 1963 and 1997 (Ref 9) • East Coast - The sheltered east coast is relatively stable. The inland marshes are accreting and expanding in an eastward direction

Control / • Duddon Estuary - Changes in the flood / ebb regime of the River Duddon will affect the channel configuration and therefore influencing features influence exposure of adjacent shorelines. The estuary also exerts a hydraulic groyne effect which impedes littoral transport of sediment. Local scale modelling Duddon (Halcrow, 2010i) was undertaken as part of CETaSS • Ebb-tide delta - Influences evolution of the open coast on either side, by dissipating wave energy and therefore affording protection to the shorelines on either side of the mouth. Probably spans from Kirkstanton Haws, to the north, to North End Haws

Duddon Estuary (Walney Island), to the south • Hodbarrow Point - Acts as a resistant control point • Channels and banks - Channels and banks are continually changing in position and this can influence water depths and local (influence on open coast) on open (influence shoreline exposure and therefore evolution of the shoreline • Hodbarrow Barrier - Acts to fix the shoreline position and constrains movement of channels • Askam Pier – Local influence on sediment movement and fixity for channel • Dunnerholme – Local influence on shoreline exposure upstream • Salthouse Pool - Fixity for channel

Sediment sources • Ebb-tide delta - The delta provides a source of sand for aeolian transport into the dune systems • North End Haws - It is likely that the extension of the North End Haws spit provides a store / source of sediment for the estuary • Irish Sea - Sediment deposits within the outer estuary will be derived from the Irish Sea and reworking of sediments within the estuary itself. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow,

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Table 4.8 Sub-Cell 11c - Supporting information for Conceptual Understanding Location Conceptual Understanding 2010c) • Shoreline and nearshore zone from Kirksanton Haws to Annaside

Sediment sinks / • Duddon Estuary - A weak sink for sand and mud stores • Haverigg Haws - Sediment store • Sandscale Haws - Sediment store • Ebb-tide delta - Sediment store • North End Haws - Sediment store • Saltmarshes - Sediment stores

The CETASS project made an assessment of estuaries throughout the Cell11 region including the Duddon (Halcrow, 2010f, 2010g). Additionally Halcrow (2010i) made a more detailed assessment of the Duddon Estuary.

Sediment pathways / • Net movement of fine sand due to tidal currents into the estuary. The regional tidal and sediment modelling was carried out as part dynamics of CETaSS including offshore dynamics (Halcrow, 2010c) supports this finding • The Scarth Channel may interrupt the feed of sediment from Walney Island • Sandscale Haws - Evidence suggests transport of sediment into the estuary around the dune system, but also movement of shingle around Lowsy Point into the Scarth Bight. The protection afforded by Walney Island to the Barrow-in-Furness frontage means that there are no waves to drive littoral transport from this shoreline onto Sandscale Haws

Hydrodynamics • It is a macro-tidal, shallow estuary, with an average tidal range of 6.5m, but a maximum of 10.4m • The estuary shows spatial separation of flood and ebb-dominant currents, with flood current entering the estuary along its eastern margin and ebb currents leaving the estuary along its western margin (Ref 12)

Beach & Shoreline • Sandscale Haws - A net trend of accretion, where evidence suggests a southward extension of Lowsy Point (Ref 7) where a lobe Response of shingle is moving around the coast, into Scarth Bight. Also, a trend of accretion along the northern shore, which has resulted in the development of a new foredune ridge several hundred metres long

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4.4.3 Issues and Uncertainties Uncertainties in the present regional understanding of the Sub-cell 11c region have been assessed within the following strategic studies and plans:

• The first round SMP (Shoreline Management Partnership, 1999c);

• SMP 2 (Halcrow, 2009a);

• Futurecoast (Halcrow, 2002);

• A stakeholder workshop held during Phase 1 of the CETASS stage 1 studies;

• CETaSS studies;

• JPS studies; and,

• The Environment Agency’s 2011 study: coastal flood boundary conditions for UK mainland and islands .

Details of the key issues and uncertainties and where information can be found to support improved understanding of the issues and uncertainties associated with sub cell 11c are provided in Appendix A.

The reports for the 2010 monitoring for the Wyre, Morecambe and Barrow frontages were made available. As a result, there was good coverage of the 11c area and the monitoring carried out.

The CETASS studies, as well the regional and Council Reports, have addressed some of the uncertainties that were identified in the original CERMS Baseline Report (Halcrow, 2010a), notably: • Role of skears (scars) – The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. CERMS will provide additional data on extent and levels of these features to aid improved understanding of their role;

• Better understanding of littoral drift behaviour identifying quantities. This uncertainty has been ansered to a certain extent by the littoral transport modelling (Halcrow, 2010d);

• Reasons for recent saltmarsh erosion, coastal squeeze losses. The issue of coastal squeeze was investigated as part of CETaSS (Halcrow, 2010k). Additionally Halcrow (2011b) made a more detailed assessment of coastal squeeze in the Kent Estuary. However, further more detailed examination of terrestrial monitoring data and examination of aerial photographs would be needed to make better local assessments;

However, the following uncertainties remain:

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• An investigation of sea bed and water levels within the Lune, Kent and Leven estuaries and the Walney Channel - Data to be supplied from CERMS programmed hydrographic surveys;

• Cliff erosion rates (Heysham to Roa Island and Walney Island) - Defined from examination of beach survey and cliff edge monitoring information;

• Mobility and future change of the banks and channels in the outer Duddon estuary and influence on shoreline evolution - Data to be supplied from CERMS programmed hydrographic surveys and LiDAR data; and,

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4.4.4 Interpretation of Existing Monitoring Data

When the Baseline Report was published there was little information on the monitoring which had taken place in this sub-cell. The key points from this year’s monitoring reports are summarised for the various frontages within the sub cell:

Fleetwood

Analysis of beach profiles for the period 1992 to 2010 has been undertaken for Cleveleys and the River Wyre (Flyde coast) and Knott End-on-Sea to Pilling (Piling coast) coastal frontage. Although the beach profile data set is incomplete in parts, enough profiles exist to draw some conclusions:

• With the exception of the profiles adjacent to the Boat Lake, the profiles between Rosssll Point and the River Wyre have shown an accretionary trend.

The findings of this study are in parts consistent with the findings of the previous beach profile analysis undertaken by Lancaster University. Additional data examination required to inform (WBC/LCC ongoing), to be added in future revisions of the Annual Monitoring Report.

River Wyre to Heysham

The Wyre Beach Monitoring Report for 2010 showed that to the east of the River Wyre, the profiles have accreted and there has been little variation in contour movement or gradient over time. Beaches located around the mouth of the Wyre and to the east along the Piling frontage are dominated by sand and mud sediment.

Heysham and Morecambe

At Morecambe beach monitoring was carried out and it was considered that there was:

• Small amount of beach steepening in front of Hard (concrete wall) defences.

• Large amount of sediment accretion in front of soft (rock armour) defences.

• Significant accretion from Stone Jetty to Whinnysty Lane.

Other monitoring has been carried out but this has not augmented the conceptual model.

Arnside to Teal Bay

• No monitoring report was received for 2010

River Kent to Roa Island

• No monitoring report was received for 2010

Walney Island and Barrow

The 2010 monitoring data for the Barrow and Walney area have supported the current understanding presented in the conceptual model. The 2010 beach surveys show that beach volumes along the west coast of Walney have reduced by approximately 930,000m3 over the period of 1993 to 2010. This equates to an average reduction of

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elevation across the entire beach on the west coast of Walney of 440mm though these figures should be taken as an indication of trends rather then as accurate figures due to the methods used and the changes in methods between surveys.

Duddon Estuary

• No monitoring report was received for 2010

4.4.5 Conclusions The 2010 monitoring reports from Lancaster, Wyre and Barrow have added some clarity to the overall conceptual model. However, no observations were made which challenge the overview presented in the 2009 Baseline Report. Appendix H of the CETaSS Report (Halcrow, 2010j) has gone some way to clarifying the behaviour of Morcambe Bay as a whole and this has resulted in minor updates to the conceptual model diagram presented in this report. The CETaSS study also clarified the behaviour of the Duddon Estuary through localised modelling (Halcrow, 2010i).

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4.5 Sub Cell 11 D

4.5.1 Summary Sub-Cell 11d (Figure 4.7) extends between Hodbarrow Point, Haverigg and St Bees Head. No monitoring reports from 2010 were made available so the conceptual understanding of the coastal dynamics in this sub-cell remains unchanged.

Figure 4.7 Location map for sub-cell 11d The main coastal features are: • Ravenglass Estuary Complex: Rivers Esk, Mite and Irt; • Two smaller river systems: the Calder and Ehen; • A backshore comprised of soft clay cliffs and dunes and the headland at St Bees; • A foreshore composed of sand and shingle beaches; and,

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• Dune systems at Haverigg Hawes, Kirkstanton Hawes, Eskmeals and Drigg. At the northern limit of this stretch St Bees Head is a significant headland, which protrudes into deeper water and is both a control on the evolution of this shoreline and a barrier to littoral drift. The Ravenglass and Duddon estuaries also affect open coast processes, where estuary channels act as hydraulic groynes and ebb-tide deltas at the estuary mouths help to dissipate wave energy and provide protection to adjacent coasts. Erosion of the backshore predominates throughout this section, providing sediment to the littoral drift system and up-drift beaches. However, accretion has been observed in the large sand dune areas along the frontage.

4.5.2 Existing Understanding Wave and Tidal Conditions

The dominant wave direction is from the west-south-west and south-south-west. The wave climate is limited by the length of fetch available in the Irish Sea. The annual 10% exceedance significant wave height is 1.5 to 2m. Aeolian transport is also important in the control of dune system development (Motyka and Brampton, 1993). Tidal residual currents are directed from the west at St. Bees Head and from the north-west for the remainder of the coastline. Tidal currents are important in the transport of material into the estuarine mouths (Motyka and Brampton, 1993). The mean tidal range is 6.2m at Barrow. New calculations for extreme water levels at various sites in .Sub-Cell 11d are provided in Table 4.9. These tables show present day estimates of extreme levels and do not allow for sea level rise. These levels present the baseline data to which sea level rise predictions need to be applied.

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Table 4.9 Extreme Water levels for various sites in sub-cell 11d (mOD). From the Environment Agency study Coastal Flood Boundary Conditions for UK mainland and islands (Environment Agency, 2011). Alongshore chainage is given for each site. The Environment Agency state that values provided by this study can be considered accurate to one decimal place.

Return Silecroft Annaside Ravenglass Braystones St Bees Period Estuary Head (years)

CHAINAGE 1332 1338 1348 1360 1372

1 5.19 5.16 5.24 5.13 4.97

10 5.56 5.51 5.59 5.47 5.31

25 5.7 5.64 5.73 5.59 5.44

50 5.8 5.74 5.84 5.68 5.55

100 5.91 5.85 5.95 5.77 5.65

250 6.05 5.98 6.1 5.89 5.78

500 6.15 6.08 6.2 5.97 5.88

1000 6.24 6.18 6.31 6.05 5.98

10000 6.56 6.5 6.67 6.31 6.31

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Sediment transport

Between the Duddon Estuary and St Bees Head the net sediment transport is generally northwards. However, the alignment of the coast, almost perpendicular to the predominant wave direction, means that the net drift is low and direction can be variable. Local reversals occur at Whitbeck and Seascale. Any sediments currently being supplied to beaches are derived predominately from erosion of the boulder clay along the foreshore and in the nearshore zone. CETASS has shown that offshore trainsport id northwest to southeast direction with both the Duddon and Ravenglass estuaries being a sediment sink. Onshore the transport is generally in a northern direction upto the Ravenglass estuary complex. To the north the modelling agrees that the transport is variable but returns to a more northerly direction around St bee’s head. Anthropogenic Modifications The coast between the Duddon Estuary and Ravenglass Estuary is largely undefended, with very little human modification. Along the coast there are only short stretches of defences and works associated with the small developments, or other activities, such as the use of Eskmeal Dunes as an MoD site. Within the Ravenglass estuary there have been various modifications, including land reclamation for agriculture; the construction of railway viaducts; mining of haematite; and tipping of slag deposits. All these changes will have affected the estuary functioning and also affected shoreline evolution at the estuary mouths.

North of the Ravenglass Estuary, a key anthropogenic modification is the railway line, which runs along the back of the beach from Seascale to St Bees. There are a number of short lengths of defences associated with the railway line, which have limited the input of sediments from cliff erosion. There are also a number of properties built on the beach seaward of the railway which will become increasingly at risk of inundation and are expected to be largely unsustainable in their current position in the long term. Other built assets along this stretch include the Sellafield nuclear waste processing and storage facility and Drigg low-level waste storage site, and the settlements of Seascale and St Bees. Conceptual Understanding A summary of the conceptual understanding of coastal processes along the .Sub-Cell 11d frontage is presented in Table 4.10 and illustrated in Figure 4.8.

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • Duddon Estuary - The ebb-tide delta affects the evolution of the open coast up to Kirkstanton Hawes to the north, by dissipating influencing features wave energy and therefore affording protection to the shoreline. Any changes in the size of this delta will therefore affect future shoreline evolution along the adjacent open coast stretches. Local scale modelling Duddon (Halcrow, 2010i) was undertaken as part of CETaSS. The CETASS project made an assessment of estuaries throughout the Cell11 region including the Duddon (Halcrow, 2010f, 2010g) • Hodbarrow Point - A rocky limestone outcrop which is resistant to erosion and therefore forms a narrow control point along this shoreline • Selker Point - A rock platform extends several metres seaward, forming a small promontory which impacts on wave processes at this location, resulting in a potential drift divide • Ravenglass Estuary - Impacts upon local sediment processes which has resulted in the development of spits at the mouth Hodbarrow Point to Eskmeals to Eskmeals Hodbarrow Point • Eskmeals dune spit - Influences the locations of low water channels and their point of confluence. The spit represents a potential future sediment source which could affect the future evolution of the adjacent shorelines

Sediment sources • Duddon Estuary ebb-tide delta - Provides a source of sand for aeolian transport into the dune systems • Dunes (Haverigg Hawes, Kirkstanton Hawes) - Potential sediment sources in the future • Cliffs (Silecroft to Annaside) - A key contemporary source of sediment. Erosion of the till cliffs provides a wide range of sediments to the beach systems, from muds to boulders, and there is believed to be sufficient till along this coast to provide an effective sediment supply over the next century (Ref 1) • Eskmeals Spit - The dunes and shingle ridges represent a potential sediment source in the future

Sediment sinks / • Duddon Estuary - Sediment sink (sands and silts). Local scale modelling Duddon (Halcrow, 2010i) was undertaken as part of stores CETaSS. The CETASS project made an assessment of estuaries throughout the Cell11 region including the Duddon (Halcrow, 2010f, 2010g) • Ravenglass Estuary - Sediment sink (weak sink for fine sands and silts) (Halcrow, 2010g) • Offshore banks - Sediment sinks / stores. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Haverigg Dunes (Haverigg Hawes, Kirkstanton Hawes) - Sediment store • Eskmeals Dunes - Sediment store

Sediment pathways / • The open coast lies almost normal to the dominant wave direction, therefore net drift is likely to be low along this coastline with

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding dynamics predominant material movement on/offshore. • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • A number of small embayments has resulted in a number of local drift divides such that net drift varies in direction along this coastline • The Duddon Estuary, as it discharges to the sea, exerts a hydraulic groyne effect, which impedes littoral transport of sediment. Local scale modelling Duddon (Halcrow, 2010i) was undertaken as part of CETaSS • Training walls, on the western side of the channel where Haverigg Pool discharges to the sea, appear to be a barrier to littoral transport • Haverigg - Sediment is transport eastwards, into the Duddon Estuary • Haverigg Point - Progressive accretion of shingle ridges along the Haverigg Point frontage, with the source of shingle assumed to be from the north (Ref 2). Accretion linked to erosion of the shingle beach at Silecroft • Silecroft - Futurecoast (Ref 1) reports that there is a net northward littoral drift of sediment along this frontage, which is fed by the erosion of the outer Duddon sandbars. However the possibility of drift southwards during certain conditions is also recognised • Silecroft to Eskmeals - A net northward drift is supported by the northward extension of the Annaside spit (Ref 1) • Eskmeals - Although a net northward drift is reported, the growth of the distal end of the Eskmeals spit into the mouth of the Ravenglass Estuary is probably a result of a sediment circulation pattern within the mouth of the estuary (Ref 1)

Hydrodynamics • Lower tidal range and rotational tidal currents means that this section is less dynamic than coastlines further south • Haverigg - The shoreline is directly exposed to south-westerly waves, but the wide foreshore and offshore banks of the Duddon Estuary help to dissipate the wave energy

Beach & Shoreline • Haverigg - The sand foreshore fronting the town has accreted over recent years and historical Ordnance Survey maps suggest a Response seaward advance of Mean High Water line position (Ref 2). To the east of the Haverigg Pool a ‘green beach’ seems to be developing, indicating rising foreshore levels • Haverigg Point - Progressive accretion of shingle ridges along the Haverigg Point frontage, the most landward of which is approximately 200 to 250m from the shoreline (Ref 2) • Kirkstanton Hawes to Selker Point - Cliff erosion between 0.1-0.5m/yr (Ref 1). Contemporary data and visual inspection indicates relative stability in recent short term

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding • Stubb Place - Cliff erosion estimated to be between 0.2-0.5m/yr (Ref 3) • Eskmeals Dunes - Negligible erosion over the next 100 years is predicted (<0.1m/yr) (Ref 1)

Control / • Ravenglass Estuary - Impacts upon the local sediment processes, changes within these could affect the future evolution of the influencing features spit-dune complexes that exist on either side of the mouth • Channels - Act as hydraulic groynes by inhibiting the wave-driven transport of sands • Ebb-tide deltas - Act to dissipate wave energy and therefore provide protection to the open coast shorelines on either side. The open coast) area of influence is believed to span approximately 3km, protecting both the Drigg and Eskmeal dune system. Any changes in the size of this delta will therefore affect future shoreline evolution along these stretches Ravenglass Estuary Ravenglass Estuary • Spits (Eskmeals, Drigg) - Influence locations of low water channels and their point of confluence

(influence on (influence Sediment sources • There is not thought to be an onshore movement of sand or coarser sediment from further offshore, therefore reworking of the cliff and beach deposits along the open coast is likely to be the primary supply of sediment to the estuary. • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • The ebb-tidal delta is likely to provide a source of sand for aeolian transport into the dune systems

Sediment sinks / • Ravenglass Estuary - Weak sink for fine sand and silt (Halcrow, 2010g) stores • Offshore banks - Sediment sinks / stores. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e)

Sediment pathways / • At the mouth of the Ravenglass Estuary the growth of the two spits illustrates that littoral drift is towards the estuary, probably as dynamics a result of sediment circulation within the outer banks • The estuary, as it discharges to the sea, exerts a hydraulic groyne effect, which impedes littoral transport of sediment

Hydrodynamics • A macro-tidal estuary, with a tidal range of over 7m on spring tides • The estuary has relatively high tidal discharges and velocities (Ref 4), but the rivers that feed into it have relatively low discharges (Ref 5)

Beach & Shoreline • The gap between the two spits that fringe the mouth of the Ravenglass Estuary is narrowing, with the Drigg northern spit growing Response more rapidly than the Eskmeals spit to the south

g g ri D Control / • Ravenglass Estuary - Impacts upon the local sediment processes

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding influencing features • Offshore scars (Carl Crag, Barn Scar, Whitriggs Scar) - Have localised influence on the shoreline by dissipating wave energy. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Small headlands (The Knoll Nethertown, Coulderton) - The small headlands along this coast may also act as partial barriers to alongshore movement of the upper beach sediments • Cumbria Coast Railway - Effectively cuts off much of the cliff from the beach system • St Bees Seawall - The seawall is currently holding the shoreline in an unnatural position, seaward of where it would be if unprotected • St Bees Head - Is both a control on the coastal evolution of this shoreline, providing shelter to St Bees, and is a barrier to littoral drift

Sediment sources • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c). The CETASS project also made an assessment of littoral transport along this stretch of coast (Halcrow, 2010d) • Nearshore zone – Previously it had been suggested that there was a possible source of sand sized sediment to the system, although there was no quantification of this onshore transport mechanism. However, the regional tidal and sediment modelling carried out as part of CETaSS indicates that there is limited ponteial for the onshore supply of material to this stretch of coast. • Beaches - A key contemporary source of sediment along this coast • Unprotected cliffs and dunes - Drigg to Seascale; Seascale to River Calder • St Bees Golf Course cliffs - A key contemporary source of sediment. Erosion of the till cliffs provides a wide range of sediments to the beach systems, from muds to boulders • St Bees Head - Rock debris from erosion of the cliffs is likely to remain on the platform for some time, where it will be gradually broken down by wave action. Eventually, once fine enough to be mobilised by waves, it is likely to be transported to the adjacent shorelines. The headland is therefore a contemporary source of sediment, but the slow erosion rates means that it is not contributing significant volumes of sediment to the beach budget • Rivers Calder & Ehen - River flows move fluvially derived sediments downstream onto the shoreline

Sediment sinks / • Ravenglass Estuary - Weak sink for fine sand and silt stores • Drigg Dunes - Sediment store • Ehen Spit - Derived from southerly longshore drift • Offshore banks - Sediment sinks / stores

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding • Lee side of St Bees Head – Accumulations from northerly drift

Sediment pathways / • Littoral sediment transport of shingle is low along this stretch due to the orientation of the coastline relative to the predominant dynamics wave direction. CETaSS undertook littoral transport modelling (Halcrow, 2010d) • Drigg - The southward growth of the spit suggests the dominant drift is towards the south, which may be as a result of a larger circulation pattern within the mouth of the Ravenglass Estuary, with material potentially being moved from the outer banks of the estuary onto the spits on either side • Ehen / Calder - It is thought that the combined flow of the Calder and Ehen is sufficient to maintain a self-cleansing estuary mouth. There seems to be a sediment circulation associated with the estuary which has resulted in sediment accumulations on either side of the mouth. The estuary seems to be at least a partial barrier to any littoral drift from the north across the frontage, but is unlikely to affect the movement of sand across the lower foreshore • Braystones to Seamill - The coarser upper beach sediment tends to be only mobilised during storm conditions, when the main mechanism of transport seems to be cross-shore drawdown • St Bees - The orientation of this shoreline, and the shelter afforded by St Bees Head means that this shoreline is only exposed to waves from the south-west to south-south-east and therefore there is only a narrow window of waves that can drive southwards drift. Potential drift rates therefore tend to be low. The coarse nature of the upper beach sediments also means that these sediments are only likely to be mobilised by high energy events (Halcrow, 2003). Any alongshore transport of shingle is currently restricted by the groynes. The beach is, however, prone to cross-shore movement and material tends to be draw down during storms • St Bees Head - Is a barrier to littoral sediment transport in either direction.

Hydrodynamics • Less dynamic than coastlines further south, due to the lower tidal range and weaker tidal currents with rotational residuals. • Generally close to normal wave orientation with some sheltering by the Isle of Man.

Beach & Shoreline • Drigg Dunes - relatively stable, erosion <0.1m/yr Response • Barn Scar - Simple cliffs, erosion between 0.1 and 0.5m/year (Ref 1) • Seascale - Simple cliffs prone to failure through erosion and small landslides (less than 10m due to a single event), recession potential was determined to be between 0.5 to 1m/year (Ref 1) • Seascale to Sellafield - The dune fronts show some signs of activity, with cliffing present, but erosion is likely to be confined to storm events. There are no signs of dune accretion, apart from at the mouth of the Calder/Ehen, where there appears to be some dune growth due to protection resulting from the estuary delta and spit development at this location. The response of the dunes is

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Table 4.10 Sub-Cell 11d - Supporting information for Conceptual Understanding Location Conceptual Understanding extremely limited by the embankment, which cuts off the majority of the dune field from the coast • Ehen Spit - The spit has extended in length and migrated slightly in a landward direction, which has resulted in the channel moving towards the Sellafield shoreline • Braystones to Nethertown - General contemporary trend of loss in volume of upper shingle beach (Ref 7) • Nethertown - Erosion rates approximately 0.1m/yr along the southern and central sections of ‘The Knoll’ and 0.2 to 0.3m/yr on the northern side (Ref 3). Anecdotal information from residents suggests that beach levels have also been dropping • St Bees Golf Course - Estimated rates of retreat of 0.2 to 0.5 m/yr from SMP1 (Ref 2, 6). Historical Ordnance survey maps also show some retreat of both mean high water mark and mean low water mark positions. These data suggest that mean low water has been retreating faster than mean high water, which would mean that the beach is becoming generally coarser in composition and consequently narrowing • St Bees Head - The cliffs are retreating at a very slow rate, through both gradual erosion and rock falls. Studies using historical Ordnance Survey maps and photographs, have identified a mean rate of change of approximately 0.15m/year

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4.5.3 Issues and Uncertainties Uncertainties in the present regional understanding of the Sub-cell 11d region have been assessed within the following strategic studies and plans:

• The first round SMP (Bullen Consultants Ltd, 1998a);

• SMP 2 (Halcrow, 2009a);

• Futurecoast (Halcrow, 2002);

• A stakeholder workshop held during Phase 1 of the CETASS stage 1 studies;

• The CETaSS studies;

• The JPS modelling; and,

• The Environment Agency’s 2011 study: coastal flood boundary conditions for UK mainland and islands.

Details of the key issues and uncertainties and where information can be found to support improved understanding of the issues and uncertainties associated with sub cell 11d are provided in Appendix A.

None of the local council reports for monitoring in 2010 were provided .Sub-Cell 11d. However, the CETASS studies have addressed some of the uncertainties that were identified in the original CERMS Baseline Report (Halcrow, 2010a), notably:

• Collection and collation of tidal data to support better definition of extreme water levels and exposure conditions at the shoreline. This has been provided by the JPS study (Halcrow, 2011a); • Limited knowledge of direction and magnitude of sediment drift along this frontage. This has been provided by CETASS littoral transport modelling (Halcrow, 2010d). Additionally the regional tidal and sediment modelling carried out as part of CETaSS indicates that there is limited ponteial for the onshore supply of material to this stretch of coast. • Role of skears (scars) – The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. CERMS will provide data on extent and levels of these features to aid improved understanding of their role; • Evaluation of the loss or gain of saltmarsh and mud/sandbanks within the estuaries - The issue of coastal squeeze was investigated as part of CETaSS (Halcrow, 2010k). Additionally Halcrow (2011b) made a more detailed assessment of coastal squeeze in Moricambe Bay. However further more detailed examination of terrestrial monitoring data and examination of aerial photographs would be needed to make better local assessments. • The collection of sediment particle size data across the sub cell has provided data to assess potential sediment movement behaviour for correlation with recorded surveys and consequent improvement of conceptual understanding of process behaviour (Halcrow, 2010d).

However, some of the uncertainties and issues raised in the Baseline Report remain:

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• Erosion rates - Defined from examination of beach survey and cliff edge monitoring information; and, • Dune behaviour (Drigg and Eskmeals spits) – Topographic Beach and Dune Surveys and LiDAR data collected provides data to address this uncertainty.

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4.5.4 Interpretation of Existing Monitoring Data

General

• Predominant wave action south of St Bees Head is shore normal but wave action from either side of normal can induce longshore movement of the beach in a northerly or southerly direction.

Haverigg to Eskmeals

• Across the Kirksanton to Tarn Point frontage little short term change appears to be taking place with trends indicating general upper shingle beach stability but lower sand beach volatility.

• There .are no data presently available from the monitoring to support change between Tarn Point and the Eskmeals estuaries. Visual observations suggest relative stability but there is some evidence of on-going natural upper beach roll back locally at Stubb Place.

Ravenglass Estuaries

• The limited monitoring at Ravenglass shows little change taking place.

Drigg Dunes to St Bees Head

• There is no monitoring currently carried out to support definition of change between the Eskmeals estuaries and Seascale.

• Monitoring across the Seascale frontage only commenced in 2008 but data between the village and the Calder Viaduct collected by the Environment Agency indicates northerly drift across this section.

• There is no monitoring currently carried out to support definition of change between the outlets of the Calder and Ehen.

• Between the Ehen and Nethertown the beach appears to be behaving similarly to that between Kirksanton and Tarn Point with general upper shingle beach stability but greater lower sand beach volatility. Overall trends indicate loss in volume across this frontage.

• Between Nethertown and Seamill similar behaviour appears to be occurring as south of Nethertown but with only a marginal trend to erosion.

• CBC Monitoring across the Seamill to St Bees frontage only commenced in 2008 so no data is presently available to support beach change here.

4.5.5 Conclusions Local scale monitoring within CERMS only commenced in 2008 so it is not yet possible to identify trends or draw robust conclusions from comparisons to the conceptual understanding. This should be added in future revisions of the current report when more local monitoring and interpretation becomes available. The CETaSS work has provided

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clarification of the sediment characteristics and littoral drift on this coastline, but no significant changes have been made to the conceptual model.

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4.6 Sub Cell 11 E

4.6.1 Summary Sub-Cell 11e (figure 4.9) extends between St Bees Head and the River Sark at the Scottish Border. A monitoring report was available from Allerdale Council for 2010.

Figure 4.9 Location map for Sub-Cell 11e

The main coastal features are: • The resistant cliffed headland at St Bees Head; • A backshore comprised of soft clay cliffs (the majority of which are defended) interspersed with resistant cliffs and narrow dune fields along the open coast; • A foreshore composed of sand and shingle beaches along the open coast; • The Grune. Point .sand and shingle spit;

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• Moricambe Bay: Rivers Wampool and Waver; • Solway Firth: Large embayment with extensive sandbanks, mudflats and saltmarsh front the predominantly low-lying hinterland; and, • Inner Solway Firth: estuary of the Rivers Eden and Esk. . At the southern limit of this stretch St Bees Head is a significant headland, which protrudes into deeper water and is both a control on the coastal evolution of this shoreline and a barrier to littoral drift from the south. The presence of the Solway Firth in the north influences the behaviour of the shoreline north of Workington and is considered to play a dominant role in the evolution of the coast north of Allonby to the River Sark. Movement of principal channels within the estuary control the exposure conditions at the shoreline and influence the scale of tidal scour along the frontage. The behaviour of the shoreline between Cardurnock and the River Sark is highly influenced by the mobile nature of the tidal channels. Erosion of the shoreline predominates along the open coast frontage, releasing sand and gravel to the nearshore zone and transported alongshore in a northerly direction towards the Solway Firth which acts as a sediment sink.

4.6.2 Existing Understanding Wave and Tidal Conditions

The dominant wave direction is from the south-west. The wave climate is limited by the length of fetch available in the Irish Sea and interrupted from the WSW sector by the Isle of Man. The annual 10% exceedance significant wave height is 1 to 1.5m. The most recent monitoring report for Allerdale Council states that wave energy and conditions during 2009, were similar in direction to previous years’ but of significantly reduced magnitude, with 2009 being the least stormy of the last ten years (Allerdale, 2011). Tidal residual currents are directed from the west at St. Bees Head and from the north-west for the remainder of the coastline. Tidal current action is the dominant process in the Solway Firth (Motyka and Brampton, 1993). In addition, the tidal energy through St George’s Channel is greater than through the North Channel, which, combined with the funnelling effect of the coastline, results in fast tidal streams at this location (>1.5 m/s). Bed currents generally flow northwards and eastwards towards the head of the Solway. At Redkirk, (near the head of the Solway Firth) during spring tides, the ebb tide lasts approximately 6 hours, followed by a 5 hour slack period at low water. The subsequent flood tide rises 4m in 2 hours, creating the potential for tidal bores to form (Solway Firth Partnership, 1996). The nature of the tidal asymmetry results in an upstream transport vector (Solway Firth Partnership, 1996). The mean tidal range is 5.9m at Maryport. Extreme sea level predictions have however, been derived for the North West England coast as part of a number of tidal flood mapping projects. The calculated extreme sea levels for Sub-Cell 11e are included in the following tables (Table 4.11). These tables show present day estimates of extreme levels, and do not allow for sea level rise. These levels present the baseline data to which sea level rise predictions needs to be applied.

The Allerdale 2010 Report states that water level data from the Class A gauge at Workington have been obtained for the period since 1992. The data .are presented in

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Table 4.11. Quality checked data are available on a monthly basis but not until three months after the end of the month it was captured. The predicted 1 year level has been re-calculated using the additional data and, based on the 19 years of data available and is now estimated to be 5.10m OD.

Table 4.11 Extreme Tide Levels (Allerdale, 2011)

The Environment Agency study into coastal boundary conditions (Environment Agency, 2011) has also provided new extreme water level estimates (Table 4.12). The one year level for Workington from the Environment Agency study accords, within the predicted confidence limits, with the value calculated from a simplified analysis of the data from the gauge, identified above,

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Table 4.12 Extreme Water levels for various sites in sub-cell 11e (mOD). From the Environment Agency study Coastal Flood Boundary Conditions for UK mainland and islands (Environment Agency, 2011). Alongshore chainage is given for each site. The Environment Agency state that values provided by this study can be considered accurate to one decimal place.

Return Whitehaven Workington Maryport Dubmill Point Silloth Bowness-on- Period Solway (years)

CHAINAGE 1378 1388 1398 1410 1422 1434

1 5.01 5.09 5.25 5.42 5.75 6.11

10 5.36 5.44 5.61 5.79 6.23 6.84

25 5.49 5.58 5.75 5.95 6.44 7.15

50 5.59 5.69 5.85 6.07 6.61 7.41

100 5.69 5.79 5.96 6.2 6.78 7.67

250 5.83 5.93 6.1 6.36 7.01 8.02

500 5.93 6.03 6.2 6.49 7.2 8.3

1000 6.02 6.13 6.3 6.62 7.38 8.59

10000 6.34 6.47 6.64 7.05 8.05 9.66

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Sediment Transport There is wave-driven northwards longshore drift north of St Bees Head, with littoral drift volumes, which are considered to be relatively small, partially interrupted by harbours along the frontage – Whitehaven, Harrington, Workington, Maryport and Silloth. Sediment not intercepted provides a supply to the Solway Firth, which is a strong sediment sink for both fine and coarse sediment. There is evidence of longshore drift transporting .shingle north-eastwards from Skinburness. This transport results in the maintenance of the 2 km-long spit at Grune Point (Solway Firth Partnership, 1996). It has been suggested that the accretion at the head of the Solway, at Cardurnock, indicates the point at which longshore transport converges, primarily due to tidal asymmetry effects (Solway Firth Partnership, 1996). The information provided by the 2010 monitoring report supports the above view of sediment transport in sub-cell 11e. Anthropogenic Modification The Cumbrian coast has experienced a number of significant anthropogenic modifications over the last few hundred years. The Cumbrian Coastal Railway, constructed between Whitehaven and Maryport, is a major modification which presents a significant constraint to the shoreline. Harbours and ports at Workington, Whitehaven, Maryport and Silloth have acted to intercept littoral drift and consequently have reduced sediment volumes transported north along the frontage. In addition, historical reclamation using mine waste has taken place at Workington, Whitehaven and Maryport in the past.

The Inner Solway Firth and Moricambe Bay are relatively natural, largely agricultural frontages, however, there has been considerable land reclamation along the shoreline since Roman times; this has effectively moved the shoreline seaward in some locations. There are also several small settlements as well as the MoD sites at Longtown and Anthorn, located along this frontage. No new defences have been built in this area in 2010. Conceptual Understanding A summary of the conceptual understanding of coastal processes along the Sub-Cell 11e frontage is presented in Table 4.13 and illustrated in Figure 4.10.

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding

Control / • St Bees Head - Is both a control on the coastal evolution of this shoreline, providing shelter to Saltom Bay, and is a barrier to influencing features littoral drift from the south. This finding is supported by the CETaSS littoral transport modelling (Halcrow, 2010d) • Whitehaven - The harbour breakwaters have created a promontory which acts to intercept northward drift • Harrington Harbour - Harbour defences intercept northward drift which has acted to push the natural coast alignment seaward • Workington - The breakwater on the south side of the harbour has acted to stabilise the shore in this location intercepting northward drift which has acted to push the natural coast alignment seaward • Cumbrian Coast Railway - Presents a significant constraint to the shoreline by impeding natural processes, cutting off sediment supply to the beaches and hindering natural rollback of the beach

St Head to Workington Bees Sediment sources • Cliffs at Saltom Bay provide the main source of coarse material to this frontage, feeding the northerly longshore drift (Halcrow, 2010d) • Waste slag deposits on local foreshores and in artificial cliffs (Harrington – Workington) provide an additional source of sediment • River Derwent – River flows move fluvially derived sediments downstream towards the shoreline

Sediment sinks / • South Beach, Whitehaven - Sand and shingle store stores • South of Workington Pier - Shingle store

Sediment pathways / • Littoral drift, which is considered to be relatively small, is transported alongshore in a north and north-east direction toward the dynamics Solway Firth Estuary. CETaSS undertook littoral transport modelling (Halcrow, 2010d). • The promontories created by Workington Harbour, Harrington Harbour and the West Pier at Whitehaven Harbour act to intercept some sediment and consequently have reduced sediment volumes transported north along the frontage • Gravel extraction practices south of Workington Harbour result in the permanent removal of material from the littoral system along this frontage, however this occurs in the hinterland so does not affect processes at present

Hydrodynamics • Dominant south westerly waves and residual tidal currents

Beach & Shoreline • Saltom Bay - Erosion rates of active cliffs is low, between 0.1 and 0.5m/year (Ref 1) Response • South Shore Cliffs, Whitehaven - The artificial mine waste cliffs immediately south of the pier are vulnerable, due to wave interaction with the west pier, with storms potentially causing 2-3m erosion (Ref 2). Here, material does not appear to remain on the beach but may be drawn offshore and out of the local regime • Redness Point - Erosion rates of active defended cliffs is very low, less than 0.1m/year (Ref 1) • Parton to Harrington - Erosion rates of active defended cliffs is very low, less than 0.1m/year (Ref 1)

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding • Moss Bay - Active erosion of cliffs (Ref 3) • Workington - Erosion rates of active defended cliffs is low, between 0.1 and 0.5m/year (Ref 1) • Whitehaven to Workington - The majority of beaches along this frontage are experiencing steepening and narrowing

Control / • Workington - The harbour breakwater intercepts northward drift influencing features • Maryport - The south harbour breakwater intercepts northward drift and has acted to stabilise the shore in this location, locally pushing the natural coast alignment seaward • Artificial defences north of Maryport – Prevent natural foreshore/cliff interaction • Dubmill Point - An artificially reinforced natural promontory, which wants to setback, presently held by coastal defences to the highway • Cumbrian Coast Railway – Where it is defended (only between Workington and Flimby) it is preventing natural erosion from providing a sediment supply to the beaches and hindering natural rollback of the shoreline • Solway Firth - The behaviour of this frontage is strongly influenced by the Solway Firth. Channel and bank movements within the Workington to Dubmill Point estuary mouth can significantly influence the degree of exposure of the shoreline

Sediment sources • Eroding cliffs and dunes (Siddick, North Flimby, Allonby Bay) provide the main source of sediment along this frontage • Waste slag deposits on local foreshores and cliffs provide an additional source of sediment • Erosion of till also releases sand and gravel sediments into the nearshore zone which tends to remain within the nearshore zone and is moved northwards alongshore

Sediment sinks / • South of Maryport Harbour – Upper beach drift store stores • Dubmill Point - The wide intertidal zone to the south of the frontage at Dubmill Point acts as a ‘minor’ sediment sink • Solway Firth - Intertidal sediments which form the outer mouth of the estuary stretch southwards along the Allonby embayment, creating a ‘minor’ sediment sink

Sediment pathways / • Littoral drift is transported alongshore in a northerly and north-easterly direction toward the Solway Firth. CETaSS undertook dynamics littoral transport modelling (Halcrow, 2010d) • The sediment transport rate along the Allonby frontage is estimated to be in the range of 10,000m3 to 20,000m3/ year (Ref 4), with most of the littoral drift from the south actually by-passing the inner Bay

• Sediment drift feed to the shorelines to the north is partly interrupted by the harbours of Workington and Maryport and consequently, sediment volumes transported north along the frontage have reduced

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding • Potential sediment transport rates are more than double at Allonby compared to those further south at St Bees Head, but still remain relatively small (Ref 3) • Only very small amounts of sediment are moved onshore by wave activity, from the large gravel deposit offshore of Workington (Ref 4)

Hydrodynamics • Dominant south westerly waves and residual tidal currents. This was confirmed by the regional modelling undertaken as part of the CETASS project (Halcrow, 2010c) • The promontories at Maryport and Dubmill Point act to concentrate wave activity at the headlands and disperse wave energy within the Bay itself (Ref 4)

Beach & Shoreline • Siddick - Erosion rates of active cliffs is low, between 0.1 and 0.5m/year (Ref 1) Response • North Flimby - Erosion rates of active cliffs is low, between 0.1 and 0.5m/year (Ref 1) • Workington to Maryport - Vegetated dunes fronting the railway embankments are experiencing erosion and beaches are now steepening (Ref 3) • Maryport - Accretion south of the pier, however, experiencing dropping foreshore levels overall; this is attributed to a significant decrease in material supplied to the frontage by littoral drift (Ref 5) • Maryport Golf Club - Analysis of historic OS maps from the 1900s and 1970s, as part of SMP2 studies; suggests that the low cliffs have eroded approximately 85m over the 70 year period, giving an average erosion rate of around 1.2m/year • Saltpans - Erosion rates are estimated to be around 1m/year with erosion most likely occurring as a result of single extreme storm events (Ref 3) • Swarthy Hill - The relict cliffs at Swarthy Hill experience very low rates of retreat, less than 0.1m/year mainly due to sub-aerial erosion (Ref 1)

• Dubmill Point - Experiencing beach steepening to the south

Control / • Dubmill Point - An artificially reinforced natural promontory, which wants to setback, presently held by coastal defences to the influencing features highway • Silloth - Harbour defences have intercepted northward drift which has acted to push the natural coast alignment seaward in this

The Grune The Grune location • Coastal defences within Silloth Bay - Have effectively fixed the shoreline position, stopping natural rollback of beaches Dubmill Point to Point Dubmill • Scars - Scars along the frontage, including Dubmill Scar, Catherinehole Scar, Lowhagstock Scar, Lee Scar, Beck Scar and Stinking Crag, are important for wave dissipation and therefore play a part in controlling shoreline retreat (Ref 3). The final CETASS report

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Solway Firth - The behaviour of the shoreline is highly influenced by the hydrodynamic regime at the estuary mouth. Channel and bank movements within the estuary mouth can significantly influence the degree of exposure of the shoreline. The CETASS project made an assessment of estuaries throughout the Cell11 region including the Duddon (Halcrow, 2010g) • Swatchway Channel - Shoreline evolution is highly influenced by this channel which acts to propagate waves and draws residual tidal currents to the shoreline. The onshore movement of the channel will increase exposure and tidal energy, exacerbating erosion in the intertidal zone

Sediment sources • A small amount of sediment is transported north into this section by littoral drift • Silloth Bay - The primary sediment source along this frontage is from erosion of the beaches • Solway Firth - Some sediment is also transported into the frontage, from the Solway Firth Estuary, by residual currents within the Swatchway Channel • Some dredging material, dumped offshore may find its way back onshore during storms (Ref 3) • Solway Firth Sandbanks - The outer estuary banks are potentially a source of sediment to The Grune spit

Sediment sinks / • Solway Firth - Sediment sink (Halcrow, 2010g) stores • Silloth Dunes - Sediment store

Sediment pathways / • Littoral drift is transported alongshore in a north and north-east direction toward the Solway Firth Estuary. dynamics • A small amount of sediment is transported within the nearshore zone, south from the Solway Firth estuary towards Silloth Bay. • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c) • Material eroded from the Beckfoot frontage appears to have been transported south, accumulating and extending the intertidal area at Dubmill Point (north) • Silloth Bay - Sediment transport rates along this frontage are reduced due to the starvation of sediment by the harbour and defence works along the whole of this section

Hydrodynamics • Dominant south-westerly waves and residual tidal currents. This was confirmed by the regional modelling undertaken as part of the CETASS project (Halcrow, 2010c) • The Swatchway Channel, which is the main passageway for flood and ebb flows entering and exiting the Solway Firth, runs adjacent to the shoreline along the entire length of the frontage

Beach & Shoreline • Dubmill Point to Silloth - The backshore between Dubmill Point (north) and Silloth is generally stable, with the following

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding Response notably applying: o Beckfoot - Erosion of the backshore and beach steepening (Ref 3) o South of Silloth - Stable beach and active accretion of the dune belt (Ref 3) • Silloth Bay - Continued erosion has resulted in the lowering and steepening of beaches in this location

• East Cote (south) - Since 1980 an estimated 8,000m3 of material has been lost, and north of Longhouse approximately 5,000m3 (Ref 3)

• East Cote (north) - From 1999 to 2004 areas of the frontage for which monitoring data was available (approx 50% of the length), have experienced a decrease in volume of approximately 3,000m3 (Ref 6)

• Skinburness - Where the open coast defences end, downdrift erosion is leading to outflanking of defences and the shoreline has eroded by approximately 2m/year at this point (Ref 3)

• The Grune (Grune House) - The Grune has eroded approximately 1 to 3m in the area fronting Grune House (approximating to 0.1 to 0.3m/year) (Ref 6) • The Grune (north) - The coastline to the north has remained relatively stable (Ref 6), however since 2000 there has been evidence of ‘cliffing’ along the landward side of the low water channel fronting The Grune, indicating little or no mobile sediment cover to the lower foreshore and signifying that erosion of the clay substrate is occurring (Ref 6) • Grune Point - At present, the Grune appears to be accreting at the Point as well as along the sheltered back shore (Ref 3). Analysis of historic OS maps from the 1900s and 1970s, as part of the SMP2 study, suggests that Grune Point has accreted by approximately 70m over the 70 year period, equating to an accretion rate of around 1m/year

Control / • The Grune - The spit plays an important role in providing shelter to Moricambe Bay and the saltmarsh in its lee. Any change in influencing features the spit will therefore have consequences for Moricambe Bay • Waver Channel - Evolution of the proximal end of The Grune is influenced by the position of the Waver channel and how it connects with the Swatchway Channel at the mouth of Moricambe Bay open coast) • Scars (Stenor Scar, Tickhill Scar, Longdyke Scar) - The scars at the mouth of Moricambe Bay exert a major influence on the extent Moricambe Bay to which channels move and consequently influence patterns of erosion and accretion along these shorelines. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars. • Cardurnock - the promontory at Cardurnock acts to shelter Moricambe Bay from significant wind and wave exposure (influence on • Skinburness Marsh - provides support to the rear of The Grune spit

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding

Sediment sources • Outer Solway Firth • The Grune • Cardurnock Flatts • Within the Bay, saltmarsh and mudflats provide a source of fine sediment to the larger Solway Firth system

Sediment sinks / • Solway Firth - Sediment sink stores • Moricambe Bay - The extensive marsh systems act as a sediment sink

Sediment pathways / • Littoral drift transported north along the Grune and south along the Bowness Common frontage is deflected into and deposited dynamics within Moricambe Bay • Some sediment may be transported into the frontage, from the Solway Firth Estuary, by wave action and tidal/residual currents • Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c).

Hydrodynamics • The degree to which the Bay is exposed to wind and wave processes is directly influenced by the channel and sand bank positions within the Solway Firth and the sheltering affects of The Grune and Cardurnock promontories Beach & Shoreline Response

Control / • Solway channel and sandbanks - Changes in channel and sandbank positions, alters the degree to which the Bowness Common influencing features frontage is exposed to wave energy. A review of offshore banks was carried out for CETaSS, including characteristics and processes (Halcrow, 2010e) • Eden and Esk channels - The position, size and orientation of channels and banks determines exposure conditions along the frontage. Meandering of these channels concentrates waves and residual currents toward the coastline, resulting in localised erosion and undercutting of the saltmarsh edge

(InnerFirth) Solway • Scars (High West Scar, Brewing Scar, Howgarth Scar) - Influence the position and orientation of the tidal channels. The final CETASS report (Halcrow, 2010b) made an assessment of the origins and behaviour of scars.

Sediment sources • Sand banks (Cardurnock Flatts) - Act as a sediment source • Marshes (Rockliffe Marsh, Burgh Marsh) - Marsh systems provide a source of fine sediment to the system • Rivers Eden and Esk – River flows move fluvially derived sediments downstream into the Solway Firth Cardurnock to the Scottish Border Border the Scottish to Cardurnock

Sediment sinks / • Solway Firth - Is a strong sink for sand and, in the upper reaches, mud. Regional tidal and sediment modelling was carried out as

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding stores part of CETaSS including offshore dynamics (Halcrow, 2010c) • Moricambe Bay - Acts as a sediment sink (Halcrow, 2010g) • The Grune – Acts as a store • Sand banks (Cardurnock Flatts) - Act as temporary stores • Marshes (Rockliffe Marsh, Burgh Marsh) - Act as sediment sinks

Sediment pathways / • Evidence of coal dust concentrations in the sand suggests that some sediment has been transported northwards into the estuary dynamics from the Workington to Whitehaven coast, • (Ref 1) suggests that only limited amounts of sand are transported into the estuary from the west, due to low tidal currents depositing muddy sand at the mouth • Sediment transport within the inner estuary system appears to redistribute material internally rather than transport significant new inputs of material into the system. Regional tidal and sediment modelling was carried out as part of CETaSS including offshore dynamics (Halcrow, 2010c)

• Sediment transport within the wide intertidal zone is variable as local drift reversals occur on a regular basis

• Nearshore sediment transport tends to be in a westerly direction along the southern Bowness frontage, converging with easterly sediment transport along the Cumbrian coast at the mouth of Moricambe Bay

• Some sediment is also likely to be transferred across the mouths of the Sark, Esk and Eden, the direction and magnitude of which is dependant on the movement of low water channels in the area (Ref 9)

Hydrodynamics • The inner estuary is macro-tidal and flood dominant • The funnel shape of the Solway Firth combined with its shallow depth creates strong tidal currents within the estuary • Wave heights and periods are restricted by limited fetch lengths, however, at times wave energy levels can be high • The frontage is exposed to locally generated waves

• Strong flood currents combined with prevailing south-westerly winds result in the piling up of water towards the upper estuary

Beach & Shoreline • North Bowness Common - Has experienced significant erosion as the Solway Channel has moved landward Response • Bowness-on-Solway to Drumburgh - Contemporary erosion is mainly focussed on the banks of the River Eden, for example at Glasson (Ref 3) • Burgh Marsh - Has experienced erosion due to the Eden Channel moving landward

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Table 4.13 Sub-Cell 11e - Supporting information for Conceptual Understanding Location Conceptual Understanding • Rockcliffe Marsh - Marsh accretion (Ref 3)

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4.6.3 Issues and Uncertainties Uncertainties in the present regional understanding of the Sub-cell 11e region have been assessed within the following strategic studies and plans:

• The first round SMP (Bullen Consultants Ltd, 1998b);

• SMP 2 (Halcrow, 2009a);

• Futurecoast (Halcrow, 2002);

• A stakeholder workshop held during Phase 1 of the CETASS stage 1 studies;

• CETaSS studies;

• The JPS modelling; and,

• The Environment Agency’s 2011 study: coastal flood boundary conditions for UK mainland and islands.

Details of the key issues and uncertainties and where information can be found to support improved understanding of the issues and uncertainties associated with sub cell 11e are provided in Appendix A.

The Allerdale 2010 monitoring report was provided so there is a good coverage of cell 11e. Additionally, the CETASS studies have addressed some of the uncertainties that were identified in the original CERMS Baseline Report (Halcrow, 2010a), notably:

• Limited knowledge of direction and magnitude of sediment drift along this frontage. This has been provided by CETASS littoral transport modelling (Halcrow, 2010d) • Evaluation of the loss or gain of saltmarsh and mud/sandbanks within the estuaries - The issue of coastal squeeze was investigated as part of CETaSS (Halcrow, 2010k). However, further more detailed examination of terrestrial monitoring data and examination of aerial photographs would be needed to make better local assessments;

However, the following uncertainties remain:

• There were some extensive areas of the Solway Firth where bathymetric data was limited. Analysis of change to this estuary in the future would be helped by full comprehensive bathymetric surveys at regular intervals; • Cliff Erosion rates - Defined from examination of beach survey and cliff edge monitoring information; • Changes in the orientation and form of banks and channels within Solway Firth - Data to be supplied from CERMS programmed hydrographic surveys and LiDAR data; and,

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4.6.4 Interpretation of Existing Monitoring Data

Interpretation of existing monitoring data is being made available from local monitoring reports being produced for the area. The 2010 report for Allerdale Council has been made available and has been reviewed for this update.

The key points arising from examination of available data are summarised below for various sections of frontage within the sub cell:

General • Predominant wave action north of St Bees Head is from the south west with other principal directions being from between W and WSW, across fetches between the Isle of Man and the Dumfries and Galloway shoreline

• The presence of the Isle of Man offshore, St Bees Head inshore and the orientation of the Allerdale shoreline provides significant shelter and increased focusing of waves from limited directions moving north along the shoreline.

• Generally inshore tidal currents are low in magnitude with longshore drift more likely to be instigated by wave breaking and/or wave induced currents due to oblique incident waves. This results in a longshore drift north easterly across the frontage with there being evidence of material from beaches at the south end of the shoreline found on beaches to the north.

• The drift is interrupted by river discharges and/or harbours, where structures have been built in the past to stop the drift from blocking the navigation channels. In all cases – Harrington harbour; Workington (river Derwent); Maryport harbour and Silloth harbour, some of the drift by-passes these entrances and continues northwards.

• At harbour locations beach levels/volumes are known to be influenced by artificial movement of material if it builds up.

St Bees Head to Workington

• The presence of the Isle of Man offshore, St Bees Head inshore and locally the breakwaters at Whitehaven harbour provide shelter to much of the shoreline such that wave directions are more focussed across this section of the Copeland shoreline.

• CBC Monitoring across the St Bees Head to Redness Point (north of Whitehaven) frontage only commenced in 2008 so no data is presently available to support beach change here.

• North of Redness Point the beach conditions appear to be generally stable to accreting.

• There was no foreshore monitoring available to support definition of change between the borough boundary with Copeland at Copperas Hill and the outlet of the River Derwent at Workington. Data collection commenced in 2010 in this area so at present there is no comparison data currently available

Workington to Silloth • Between Workington and Maryport previous monitoring has continued (North Workington, Flimby and Maryport South), supplemented by some additional baseline profiles. General there has been only modest change taking place across the Siddick and Flimby sections. • South of Maryport harbour little change has occurred with trends in the same direction and similar in magnitude to that observed previously. The largest trends show losses in the sections closer to the breakwater arm suggesting that material may be being moved from this section around the head of the arm.

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• Between Maryport and Dubmill Point previous monitoring has continued supplemented by some additional baseline profiles between the harbour and Bank End. Between Bank End and Dubmill Point behaviour has continued as previously observed with stability/modest accretion at the south end, slight erosion north to Allonby and accretion north of Allonby village. • Between Dubmill Point and Silloth Harbour previous monitoring has continued supplemented by some additional baseline profiles on the north side of Dubmill Point and across the Silloth Golf club frontage. o Across the Beckfoot frontage the southern half continues to erode whilst the northern half is accreting, indicative of northerly drift not being replenished by drift around Dubmill Point. o At Silloth, south of the harbour the trends are indicative of beach loss, apart from the upper beach adjacent to the harbour entrance which is accreting. Further down the beach levels are lowering suggesting that material is being transported around the head of the breakwater. Silloth to Grune Point • Between Silloth Harbour and Grune Point the beach profile is monitored at 44 locations. In 2010 there has been some modest overall increase in beach volumes across the frontage north of the East Cote outfall but losses from the area immediately to the south. • Across the artificially defended frontage (Silloth to Skinburness) the monitoring confirms ongoing beach loss • Across the Grune frontage there has been overall accretion although the majority of this appears to be on the lower beach with upper beach erosion and shoreline recession taking place across the western half of the frontage and stability/modest accretion across the upper part of the eastern section of beach. • In addition shingle drift from the Silloth to Skinburness frontage is continuing to infill immediately to the east of the rock armour revetment. Moricambe Bay • In Moricambe Bay the profile of the saltmarsh in the lee of the Grune, in front of the only artificial defences – Sea Dyke – is recorded by the Environment Agency. Up to the publication of the Baseline Report there were no other monitoring carried out Solway Firth • Before 2010 between Cardurnock and Bowness on Solway, baseline only two monitoring profiles were in existence, but in 2010 additional ones have been established to support definition of change. The two existing Environment Agency profiles at Bowness shows similar behaviour with accretive trends but clear cyclical behaviour taking place • From Drumburgh to the cell 11e boundary at the Scottish border previous Environment Agency monitoring has continued supplemented by some additional baseline profiles. However these generally only record the top level of the saltmarsh and not the sand/mud foreshore in front of it. The time series and trend plots therefore provide little data of use in examining change.

4.6.5 Conclusions Generally the monitoring carried out by Allerdale in 2010 out supports the present understanding of coastal dynamics. Minor updates to the conceptual model diagram have been made to reflect the final findings from CETaSS.

The CETaSS modelling has confirmed the dominance in this sub-cell of sediment movement into the Solway Firth. The modelling shows a dominant upwards transport for tidal and littoral transport, although there is also an export of sediment. In the field

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the cyclical behaviour observed to date will be further investigated by monitoring now that additional beach monitoring profile locations have been added in the sub-cell.

The banks and channels of the Solway Firth are mobile with channel shifting, and there is evidence of extensive erosion and deposition of sediment. This appears to be mainly internal redistribution, rather than new material input (Halcrow, 2010b). An investigation into sandbanks and their affects on the adjacent coastline was carried out as part of CETaSS (Halcrow, 2010e) and is particularly relivant to the mouth of the Solway Firth.

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5 Operational Matters

5.1 Data Collation and Management

The collection, management and storage of regional/sub regional data is carried out on behalf of CERMS partners by Sefton Council, with data distributed to partners and/or their advisors when received, or if specifically requested. Data collected by local frameworks is transferred the opposite way. This system is presently working well. All data collated under CERMS is being stored on a regional server managed by Sefton Council and at the Channel Coastal Observatory (CCO) in Southampton, which has become the data management centre for the Regional Coastal Monitoring Programmes of England and is hosted by New Forest District Council, in partnership with the University of Southampton and the National Oceanography Centre, Southampton.

The CCO provides storage facilities and presentation of data for examination and retrieval through web portals within the Channel Coast Observatory website (http://www.channelcoast.org/). At present data is hosted for the South East and South West Regional Monitoring Programmes. The web site currently allows for examination of data from CERMS which is currently being uploaded, but is not yet fully operational. At present only historical vertical aerial photography for the Liverpool Bay area is available and topographic profiles for Sefton MBC. Delays exist in making available the full CERMS datasets. There are long term issues relating to the dissemination of LIDAr data.

A risk-based model was used as the basis of operational criteria for CERMS and where new monitoring has been undertaken the risk model adopted has generally been used as the basis for defining monitoring actions.

Where existing monitoring regimes already existed these have largely remained as previously carried out, specifically where application of the risk-based approach to existing frontages identified generally good agreement between the monitoring currently being carried out and that defined under the risk- based approach.

There is, however, generally insufficient monitoring or other data available to enable a significant review of the risk assessments carried out originally. Review of the risk assessments in the future is recommended to inform and update project development. .However it is likely that it will be a further 12 months at least before improved information is available to support this, The project plan for the next phase of monitoring 2011-2016 will include a review of the risk ratings.

Data being collected under the local frameworks together with data obtained centrally and other data obtained outside of CERMS has been used to inform and produce the baseline and subsequent annual monitoring reports that have been produced to date. In addition the annual shoreline and coastal defence inspection reports are being used to prioritise maintenance regimes for existing defences and, where appropriate inform medium term plans produced by Authorities and ultimately production of coastal strategies and specific coastal defence scheme proposals. Authorities that have failed to produce reports will be identified and offered support in the production of reports. If continued failure to produce a report exists Sefton Council will step-in to ensure a report is produced.

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Conclusions from CERMS Review

Examination of the linkages between CERMS and on-going national and regional studies and research and other commercially based and non-commercial monitoring programmes has confirmed that there has been significant improvement in some areas with regard to development of contacts, expanding the knowledge base and in identification of synergies. Further work is required to engage, particularly commercial bodies, but also some public organisations, in order to provide ’best value’ for the data being collected and in identification of research needs that would assist in filling the gaps in the database and provide efficiency improvements in the collection of information.

As a result of the review specific actions were identified as being required to accord with the Original Project Plan (post review actions are identified in italics), specifically: • Tide data review to be commissioned as a matter of urgency. This was done in April 2009 and a report which contained specific proposals, as identified herein, has been produced.

• An initial review of wave buoy deployment sites should be carried out as soon as possible in order to determine the appropriate timescale for commencement of deployments. This should include consideration of different types of equipment that may be appropriate in specific locations.

• Urgent review of specific sediment data requirements for CETaSS with CERMS arrangements amended to meet both CERMS and study the study objectives. CERMS to be used as the vehicle to deliver such data, timescales allowing. In the first instance it is suggested that all existing data should be obtained and collated within the CERMS database and used to provide cell wide mapping of sediment type. Information should then be updated as and when new information becomes available. Improved liaison with Conwy required to address need for collection of sediment sampling data for management of their frontages (and potential use within CETaSS). Cell wide sediment sampling carried out during 2009 this information is being used to inform CETaSS.

• Existing local terrestrial saltmarsh extent terrestrial surveys to continue. Remainder of areas to await publication of data from national study and approach to monitoring through Environment Agency led BAP targets. Awaiting publication of Report.

• Improved liaison and interaction with NE and CCW required in years 3 and 4, so that appropriate definition of requirements can be included in the bid for monies for the next five year period.

• Improved efforts to contact external sources and obtain data that would be useful to CERMS.

• CERMS members to identify future research needs. Linkages with POL to be developed further. This is on-going. Ensure outputs from JPS and CETaSS are filtered through CERMS for comment and action. Improved research linkages with educational establishments to be developed.

• Year 2 local framework reports to be completed by September 2009 and regional report by December 2009, and yearly thereafter. This has partially been achieved.

• Links with Welsh Authorities to be maintained, to foster inclusion in the Cell 11 community. Environment Agency (North West) to develop linkages with the counterpart in Wales. Welsh Authorities to approach WAG for funding contributions towards strategic monitoring

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elements, specifically bathymetric surveys and sediment sampling. Welsh Authorities’ represented on CERMS steering group; funding for sediment sampling and contribution to aerial photography obtained but not bathymetric surveys.

With the CERMS programme only having been operational for 18 months and not fully established operationally as yet, and the CETaSS and JPS studies not yet completed, the scope for identifying significant changes to the monitoring regime beyond the initial approval period, at the present time, are limited.

The following areas have been identified, where modification of arrangements from the first project plan, may be required:

• The use of LiDAR data for more detailed monitoring of change in inter-tidal areas;

• Hydrographic surveying in the immediate sub-tidal;

• Appropriate methods for identifying changes in habitats e.g. saltmarsh; and,

• Requirements for monitoring changes in sediment characteristics.

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6 Conclusion

This report provides a baseline for coastal processes against which future monitoring reports can be compared. The report summarises the data availability, provides a regional cell wide baseline and more local baselines. IThis must be culled straight from the Baselinmew Repoet. The whole section needs re-wriring, focusing on what has been achieved in 2010, what the oyustabnding issues are / were at the end of 2010, and what is being / should be done about them.

The main findings from this report are as follows:

- That data from local monitoring frameworks and linked studies are being incorporated to CERMS to supplement the data collected by CERMS. Where these data have not been utilised, or where other third party data sources exist, every attempt should be made to access these data; this will avoid duplication of effort and provide best value to the strategy;

- The CETaSS and JPS studies, currently underway, will further supplement current understanding of the cell-wide baseline of coastal processes;

- Regarding the sub-cell baselines: generally the local monitoring reports, where available, concur with the present conceptual understanding of coastal processes in each sub-cell. In the case of sub-cell B, however, the volume of sediment in motion may vary considerably year on year, and seasonally; and,

- Comparison of local monitoring reports with the conceptual understanding is not currently possible for a number of sub-cells, because either:

- those reports are not yet ready; or,

- the datasets being reported on are not yet sufficient in size to be able to make significant comparisons against the conceptual understanding.

- Bathymetric surveys undertaken across the open coast have produced a substantial near shore baseline. Gaps in the coverage remain and should be collected in the subsequent monitoring programme.

- Colour vertical photography has been collected for substantial sections of the open coast, interpretation of the imagery should be made to ensure best value of the data collection. Areas not collected should be surveyed in the subsequent monitoring programme. Liaison with NE and EA should be undertaken to ensure interpretation is appropriate.

- Estuaries have a significant influence in the region, however, limited data sets exists for these areas. A review of the estuaries should be undertaken to identify key datasets that need to be collected and those that could be incorporated into this programme.

- SMP policy review

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comprehensive data to the next review of the SMP. In many instances further data .are required before full value can be derived from additional studies. It would be desirable to have more information on the following:

• Wave data

• Sediment provenance

• Sandbanks (specifically their evolution in location and form)

• Estuary parameters

• Bathymetry

• Coastal Squeeze

More information about the requirements for further studies is provided in Section 15 of the CETaSS Main Report. The future plan for the CERMS monitoring is presented in Section 3.3.1 below.

6.1.1 CERMS Programme Design 2011 to 2016 The following text provides an overview of the plan for CERMS in the coming years Review of Risk Based Approach to Programme Design The risk based approach to programme design adopted for the original CERMS project plan provided the basis for identifying the temporal frequency and/or intensity (spacing) of the primary monitoring elements i.e. • Inspection of coastal defence assets • Topographic and bathymetric profiles • Larger scale bathymetric surveys • Sampling of sediments • Locations for collection of hydrodynamic data Definition of the varying level of risk across cell 11 was based on the characteristics relevant to each of the management units defined in SMP1. Key points arising in relation to the risk assessment carried out and its subsequent use in definition of monitoring actions were: • It is important that the comprehensive review of the characteristics (i.e. the source, pathway, receptor, consequence assessment) of each Management Unit is only used as guidance for the appropriate monitoring regime for that frontage. • To be consistent, it is important that the results of all the major elements of such a programme are used to provide increased knowledge of the "risks" of coastal flooding and erosion, and how they are changing. To this end, the specification of the monitoring plan should be linked to a clear plan for: o Quantifying and disseminating present levels of "risk", as revealed by initial "baseline" monitoring; and

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o Assessing and presenting information on the changes in risk as the monitoring programme proceeds. o Information obtained on these two important outcomes of the monitoring should then be used to refine the “risk ratings” for the Management Units, as part of a periodic review of the monitoring programme. It is important that the monitoring programme is carefully reviewed after the first few years of operation. With completion of SMP2 in 2010 and the re-defining of frontages for policy definition as Policy Units, the exercise has been repeated for the purposes of informing the project plan for the next five years. The methodology for risk assessment is as previously adopted (Coastal Engineering, 2005). Plans showing the updated risk level for each policy unit are provided in Figure 3.1, Figure 3.2 and Figure 3.3 and, for the south, central and northern sections of frontage, respectively.

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predictions. 2. It is recommended that time series archived data from the Met Office new WaveWatch III forecasting model at all nearshore points should be obtained annually and stored in the CERMS database for comparison with measured data and for use in analysis of coastal change data. Sediments 1. Data should be collected, in association with other agencies e.g. BGS, to update mapping of sediments particularly in offshore areas to identify whether there will be sufficient sediment available to provide for future requirements. This work could include sampling and profiling surveys, possibly in conjunction with bathymetry surveys for specific areas assessed on a risk basis, guided by the results of the modelling to confirm the availability of sediment for transport and the modelled pathways. 2. Long term suspended sediment concentration data, measured close to a number of estuary mouths, would be extremely useful to examine suspended sediment concentrations and fluxes into estuaries. This can be a difficult and expensive parameter to measure over long time periods as regular instrument maintenance is required. This may be best taken forward on a trial basis for a particular estuary, in collaboration with a University or NOC. The coastal group could seek to collaborate with others when or if data collection campaigns are being planned for tidal power or other estuary studies. Comparison and analysis of concentrations with meteorological and wave data would also Sandbank A combination of LiDAR and hydrographic surveys should be used to Surveys monitor the low water extents of sandbanks that may play a critical role in limiting shoreline exposure conditions. This should focus on the banks considered most important in terms of managing coastal flood risks, so the priority would be the bank system extending south east from Constable Bank and the Shell Flat. Estuaries Combined LiDAR and hydrographic surveys of estuaries should be carried simultaneously to provide a complete snapshot of estuary form and condition. Morecambe Continuation and development of the present system of LiDAR surveys, Bay bathymetric surveys, aerial photographs and satellite images should be used to inform understanding of the changing morphology in Morecambe Bay. Bathymetric 1. Bathymetry data in some areas is old, scarce or non-existent (e.g. Surveys northern part of Morecambe Bay and parts of the Solway Firth). This should be addressed in future through improvements to coastal monitoring being put in place through CERMS. 2. In addition to establishing baseline data, for the whole shoreline, hydrographic surveying of beach profile extensions or multi-beam surveys of the nearshore area need to be continued on a regular basis in order to improve the understanding of ongoing change in nearshore and intertidal zones. These repeat surveys could be prioritised to the high risk frontages from the regional CERMS risk assessment, but they need to consider linked source / sink areas rather than just the immediate areas near the risk zones. As noted in estuaries above the bathymetric surveys should be co-ordinated as far as practicable with airborne LiDAR surveys of the intertidal areas or topographic surveys. Coastal The assessment of habitat losses and gain requires the capture of new Squeeze LiDAR and aerial photography data for intertidal areas, plus the ongoing

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collection of beach profile data. This data to be provided through CERMS.

7 Recommendations

It is recommended that recommendations for each sub cell be reviewed and opportunities for inclusion in the monitoring programme be explored. Not all of the recommendations will be able to be undertaken by the monitoring programme and those tht fall out of the programme remit or are too costly to be funpresentedded should be noted and opportunities for collaborative working explored. A summary of recommendations is detailed below and the most likely method of progressing the action detailed. The prioritisation of the recommendation is also considered

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Sub-Cell 11a wide Evolution of offshore sand banks and channels (Dee and Medium N Wales) Sediment budgets (including rates, sources, sinks, CERMS, WAG Medium direction) Sediment transport along the North Wales frontage Better understanding of littoral drift behaviour Role of Liverpool Bay as a sink Extreme water level predictions CERMS High Better definition of tidal current behaviour CERMS Low Expansion of inshore wave climate datasets to cover Low

the lower part of the Dee Estuary (L16) Great Orme Western boundary of the SMP - influence of Great Orme headland on sediment transport (L3) Llandudno The issue of fluvial and pluvial drainage from behind coastal defences increasing flood risk Great Orme to Mobility of the lower beach (composed of cobble and Rhos-on-Sea boulders) (L4)

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Current and future influence of Constable Bank, offshore of Penrhyn Bay The linkage (if any) between Constable Bank and onshore transport of sediments during certain climatic conditions (L8) Onshore-offshore sediment transfer (L6) By-passing of material around Little Orme (L5) Rhos-on-Sea to Source of the shingle beaches and mobility of sub-tidal Point of Ayr shingle deposits (L7) Onshore transport of sand Future beach recharge requirements Reinstatement of drift following intervention along the Towyn embankment (L13) Role of the ridge and runnel system - possibility of wave focusing (L9) Effects of Afon Clwyd discharge (L11) Influence of Talacre dunes erosion/accretion on sediment transport behaviour (L12) Dee Estuary Role of Dee estuary as a sediment sink. Specific report CERMS/WAG Low

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Mobility and future change of the banks and channels in Specific report CERMS/WAG Low the outer Dee estuary and influence on shoreline evolution (L20) Future evolution of the Dee Estuary approaches bank and channel system east of the Afon Clwyd and the propagation of East Hoyle sandbank across the north Wirral shoreline (L14) Development of the Mid Hoyle channel taking over from the Welsh channel / Development of the East Hoyle sandbank pushing the channel onto the Wirral coastline (L21) Influence of the Dee estuary on the adjacent open Specific report CERMS/WAG Low coastlines Sediment transport across the mouth of the Dee Specific CERMS/WAG Low report/study Onshore movement of sediment into estuaries Specific CERMS/WAG Low report/study Impact of man’s activities on current and future estuary functioning (L19) Effects of channel dredging of Welsh Channel - Port of Mostyn (L10) The medium to long term effects of recent developments between Oakenholt and Hawarden Bridge on the Dee Estuary regime (L17) Modelling of Joint wave and water levels in outer Dee

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Estuary (L18) Future morphological evolution of estuaries under SLR Specific report CERMS Medium Wirral Current and future influence of the Dee and Mersey, Specific report CERMS Low/medium and associated banks and channels, on evolution of this coastline Accretion rates along the frontage Annual Local CERMS Medium Report Land contamination issues Mersey Estuary Dredging of Mersey Estuary Specific report Proposed Mersey Crossing Future development of the Port of Liverpool (including dredging) (L24) Impact of man’s activities on current and future estuary Specific report CERMS Medium functioning (L22) Sediment transport across the mouth of the Mersey Specific study CERMS Medium (L23) Sefton Coast Current and future influence of the Mersey and Ribble, Annual Local CERMS Medium and associated banks and channels, on evolution of this Report coastline. Future vulnerability of the River Alt area (L32) Specific report Continued growth of the offshore banks and impact of Annual Local CERMS/MDHC Medium/Low this on the coastal evolution (L25) Report /tracer

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other The correlation (if any) of Formby Bank morphology study changes with deposition of dredging arisings at Jordan’s Bank (L33) Impact of training walls and subsequent dredging and spoil dumps on the transport regime (L26) Accretion rates at Crosby Annual Local CERMS High Report Land contamination at Blundellsands

Existence of a drift divide at Formby Point (L27) Annual Local CERMS Low Report / current monitoring Erosion of Formby Point Specific CERMS Medium Shoreline exposure changes to be expected with the reports, Annual ongoing retreat of Formby Point (L28) Local Report Define the limits of recession that could be reached at Formby Point, due to changes in natural process behaviour and associated effects of human interference e.g. disposal of River Mersey and Ribble dredging arisings, sewage sludge disposal, River Mersey training, etc. Role of the ridge and runnel system - possibility of Specific report/ CERMS Medium wave focusing (L29) Annual Local report

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Impact of changes in shoreline orientation (moving Specific report CERMS Low from a curved plan-shape to a straighter plan-shape) on the sediment transport regime (L28)

Influence of dune erosion/accretion on sediment transport behaviour (L31)

Sub-cell 11b Uncertainties in present understanding

Better understanding of tidal current behaviour along Current CERMS Medium the west and north facing coasts of the Fylde Peninsula Monitoring Better understanding of littoral drift behaviour Specific study CERMS? Medium identifying quantities Ridge and runnel system (Sefton and Fylde) and the Specific Report/ CERMS Medium affect on the sediment budget and shoreline response Local Monitoring report Accuracy of flood risk maps Ribble Estuary Role of estuary as a sediment sink (L34) Specific report CERMS Low

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Area Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Impact of man’s activities, including maintenance of Speciic report CERMS Medium training works on current and future estuary functioning (L35) Contamination risks Mobility and future change of the banks and channels in Specific report CERMS Medium the outer estuary and influence on shoreline evolution (L36)

Influence of the estuary on the adjacent open coastlines Specific report CERMS Medium (L41)

Sediment transport across the mouth of the Ribble Specific report CERMS Medium (L37)

Future response to sea level rise, e.g. capacity for Specific report CERMS Medium further infilling of the estuary (L38)

Impact of sand mining at Horse Bank and Salter’s Bank Specific CERMS Low (L39) report/Annual Local Reports Impacts of managed realignment Physical and/or numerical modelling of the Ribble Specific study Low estuary to be carried out to provide the best possible estimate of likely future estuary changes and to define the implications for future coastal defence provision

Fylde Coast Influence of the Ribble, Wyre Estuary and Morecambe Specific study / CERMS Medium Bay, and associated banks and channels, on evolution of Annual local this coastline report

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Area Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Impact of sand mining at Salter’s Bank Influence of the deep-water channel of Lune Deep, which is thought to afford some protection to the north Fylde Coast (L42) Dune behaviour (erosion / accretion) Annual Local CERMS Medium report and annual local monitoring Role of the banks offshore of Fleetwood (L43) Existence of a flow divergence offshore of the Current CERMS Medium Blackpool frontage (L44) monitoring Existence of a littoral drift divide in the region of Cleveleys (L45)

Understanding the source of cobbles observed along the Cleveleys frontage

Impact of coastal structures (Wyre and Blackpool) Specific study / CERMS Annual Local report Fleetwood Port (navigation channel dredging and disposal in the Lune Deep)

Key: = Regional Tide and Sediment Modelling; = Influence of Offshore Banks; = Estuary Morphodynamics; = Morphodynamics of Morecambe Bay.

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Sub-Cell 11c Role of skears (scars) in diffracting waves (L47) Specific Low wide Evaluation of how skears could be used as coastal defences if study reinforced (L47)

Movement of sediment within Morecambe Bay Specific Better understanding of littoral drift behaviour identifying study quantities

Large scale sediment budget uncertain - local studies have been undertaken, but no large-scale assimilation of data (L48)

Role of Morecambe Bay as a sediment sink (L48) Future response of Morecambe Bay to sea level rise (L48) Impact of man’s modifications (railway, reclamation) Susceptibility of coast to storm surges Extreme water level predictions, with specific emphasis on conditions in the approaches to the three main estuaries (Kent, Leven and Lune)

Better understanding of tidal current behaviour along the whole cell An investigation of sea bed and water levels within the Lune, Kent and Leven estuaries and the Walney Channel

Accuracy of flood risk maps

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Reasons for recent saltmarsh erosion - possible linkage to changes in channel form resulting in a bore-effect at later stages of the tide. Coastal squeeze losses (L49) Influence of estuaries on adjacent shorelines (L48) Changes in flood and ebb channels and banks, and their influence on shoreline evolution, both in terms of their position and also their form (i.e. width and depth) (L46)

No bathymetry of the Lune Deep

River Wyre to Historical channel shift for Wyre Heysham Protective influence of Sunderland Point and future erosion rates Heysham to Roa Influence of the Leven and Kent and associated channels and Island banks (L51) Influence of Walney Island and potential impact should the spit on Walney Island erode (L52) Influence of Heysham harbour and approach channel (L50) Changes in behaviour at Silverdale and Grange over Sands (L53) Better understanding of estuary dynamics, bank and channel changes and shoreline evolution within the Kent and Leven Estuaries

Contamination issues at Ulverston Cliff erosion rates

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Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Walney Island Existence of littoral drift divide along the central section of Walney Island (L55) Feed of sediment to and from both Duddon Estuary and Morecambe Bay (L55) Source of sediment and possibility for onshore movement of beach material (L55) Possibility of a permanent breach being maintained by tidal flows between west and east coasts (L56) Issues relating to role of historical land fill sites (L54) Erosion rates Duddon Estuary Sediment linkages with Walney Island Role of estuary as a sediment sink (L57) Potential responses to implementation of Managed Realignment (L57) Impact of man’s activities on current and future estuary functioning (L57) Mobility and future change of the banks and channels in the outer estuary and influence on shoreline evolution (L57) Influence of the estuary on the Walney Island and adjacent open coastline to the north (L58) Sediment transport across the mouth of the Duddon (L57)

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Sub-cell 11d Uncertainties in present understanding

Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Sub-Cell 11d Determination of sediment pathways and fluxes for the wide eastern Irish Sea by using numerical modelling techniques supported by available field data to enable a sediment budget to be determined for the coast Limited knowledge of direction and magnitude of sediment drift along this frontage (L59) Numerical model to determine nearshore wave conditions and sediment transport arising from individual storms and estimate annual aggregate conditions Quantification of erosion rates along the coast Direction of sediment drift along this frontage Sediment budget (including transport, sources, sinks, availability, etc.)

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Role of skears (scars) in providing localised protection to the shoreline Onshore-offshore sediment transfer Accuracy of flood maps Haverigg to St Influence of Duddon and Ravenglass estuaries Bees Head Erosion rates Ravenglass Evaluation of the loss or gain of saltmarsh and mud/sandbanks Estuary Complex within the estuaries Dune behaviour (Drigg and Eskmeals spits)

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Sub-cell 11e Uncertainties in present understanding

Area/Authority Issue / Uncertainty Likely Potential Priority Monitoring / studies that provide delivery funding data/information to address method source uncertainties CERMS CETaSS JPS Other Sub-Cell 11e Determination of sediment pathways and fluxes for the wide eastern Irish Sea by using numerical modelling techniques supported by available field data to enable a sediment budget to be determined for the coast Limited knowledge of direction and magnitude of sediment drift along this frontage (L62) Numerical model to determine nearshore wave conditions and sediment transport arising from individual storms and estimate annual aggregate conditions Quantification of sediment transport erosion rates along the coast Evaluation of the loss or gain of saltmarsh and mud/sandbanks within the estuaries (Solway Firth and Moricambe Bay) Impacts of offshore windfarms (Robin Rigg)

Potential tidal barrage

St Bees Head to Influence of Solway Firth and associated banks and channels The Grune on the adjacent shoreline (L60) Longer term influences of interventions including harbours at Whitehaven, Workington, Maryport and Silloth and coastal defences (L61) Legacy of past mine waste tipping

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Cliff erosion rates Impacts of erosion of Dubmill Point on adjacent frontages to the north

The Grune Detailed mechanisms for the geomorphological sustenance of The Grune should be identified, in particular the effect of the restriction of sediment supply from the Silloth - Skinburness coast defence works

Solway Firth Sediment dynamics within the Solway Firth (channels / banks, sediment budget) (L60)

Changes in the orientation and form of banks and channels within Solway Firth

Future response of Solway Firth to sea level rise (L60)

186

187

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Conceptual Understanding Sub-cell 11a

1. Shoreline Management Partnership (1999a) Sub-Cell 11a: Great Orme’s Head to Formby Point Shoreline Management Plan. Report produced by Shoreline Management Partnership for Liverpool Bay Coastal Group. Dec 1999, 183pp.

2. Halcrow (2002) Futurecoast. CD produced by Halcrow as part of the Futurecoast project for Defra.

3. Conwy County Borough Council (2008). Annual Local Monitoring Report 2006. Report produced by Coastal Engineering UK Limited for Conwy County Borough Council, February 2008.

4. HR Wallingford (2008) Coastal process study: Rhyl to Prestatyn. Report EC 5690, June 2008. Report produced for Martin Wright Associates, as part of the Denbighshire County Council Report on the Development of a Coastal Defence Strategy.

5. Shoreline Management Partnership (1999a) Sub-Cell 11a: Great Orme’s Head to Formby Point Shoreline Management Plan. Report produced by Shoreline Management Partnership for Liverpool Bay Coastal Group. Dec 1999, 183pp.

6. Countryside Council for Wales (2005) Investigation of Beach Levels at Pensarn Shingle Ridge. Report produced by Dr Mark Lee for the Countryside Council for Wales, Contract Science Report Number 265.

7. Barber P.C. (2006) SMP2 - Dee Estuary Issues Report. Report produced by Shoreline Management Partnership for Tidal Dee User Group

8. HR Wallingford (1991) Colwyn Borough Sea Defence Review - Report EX 2367, October 1991.

9. Conwy County Borough Council (2008) Coastal Defence Annual Inspection Report 2007. Report produced by Coastal Engineering UK Limited for Conwy County Borough Council , January 2008.

10. Denbighshire County Council (2006) Local Monitoring Report 2002-05. Report produced by Coastal Engineering UK Limited for Denbighshire County Council , July 2006.

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11. Denbighshire County Council (2008) Report on the Development of a Coastal Defence Strategy. Report produced by Martin Wright Associates for Denbighshire County Council , August 2008.

12. Flintshire County Council (Flintshire CC) (2006) Annual Local Monitoring Report 2002-05. Report produced by Coastal Engineering UK Limited for Flintshire CC, July 2006. 50pp + Appendices

13. Flintshire County Council (Flintshire CC) (2008a) Annual Local Monitoring Report 2006. Report produced by Coastal Engineering UK Limited for Flintshire CC, April 2008. 49 pp + Appendices

14. Flintshire County Council (Flintshire CC) (2008b) Annual Local Monitoring Report 2007. Report produced by Coastal Engineering UK Limited for Flintshire CC, October 2008. 50pp + Appendices

15. Jemmett A. (1999) The Beach and Sand Dunes at Point of Ayr - An Overview of Recent Changes and Management Issues. Report prepared by Dr Alan Jemmett, Project Manager Dee Estuary Strategy for the Talacre Panel.

16. Metropolitan Borough of Wirral (2000) The Beaches at West Kirby and Hoylake. Options for Managing Wind Blown Sand and Habitat Change. Report for the Metropolitan Borough of Wirral. Prepared by A Jemmett and T Smith with advice from J Houston (Sefton Council). January 2000.

17. Thomas N. and Wardle M. (2003) Foreshore Survey, Bulk Volume Analysis Monitoring Report, 1998-2002. Report produced for Metropolitan Borough of Wirral, March 2002.

18. Metropolitan Borough of Wirral Council (2007) Coastal Process Monitoring Report 2003-2006. Report produced by Wirral CC. 2007.

19. Shoreline Management Partnership (1999a) Sub-cell 11a: Great Orme’s Head to Formby Point. Context Report. Report produced by Shoreline Management Partnership for Liverpool Bay Coastal Group. December 1999.

20. HR Wallingford (2002) Crosby Marine Lake to Formby Point Coastal Defence Strategy Study. Part 1: Preliminary Studies. Report EX 4496. Report prepared for Sefton Council.

21. Coastal Engineering UK Ltd (2005) Local Monitoring Report 2003/4: Coastal process review 1999-2003. Report produced for Sefton Council, April 2005.

22. Sefton Council (2000) Coastal Defence Issues and Strategy. Sefton Council.

23. Neal A. (1993) Sedimentology and morphodynamics of a Holocene coastal dune barrier complex, Northwest England. Unpublished PhD Thesis, University of Reading

24. Pye K. and Neal A. (1994) Coastal dune erosion at Formby Point, north Merseyside, England: causes and mechanisms. Marine Geology 119, 39-56.

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26. Sefton Council (2007) Coastal defence: Report on Coastal Erosion predictions for Formby Point, Formby, Merseyside. Parts 1 and 2. July 2007. Report prepared by G Lymbery, P Wisse and M Newton.

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27. Barbour P. personal communication, (2008)

28. Environment Agency (EA) (2008) Mersey Estuary Catchment Flood Management Plan

29. Pye K. and Neal A. (1993) Stratigraphy and age structure of the Sefton dune complex: preliminary results of field drilling investigations. In: D Atkinson and J A Houston (eds) The Sand Dunes of the Sefton Coast. National Museums of Merseyside, Liverpool. pg 41-44.

30. Coastal Engineering UK Ltd (2007) Local Monitoring Report 2005/6: Coastal process review 2005. Report produced by Coastal Engineering UK Ltd for Sefton Council January 2007, revised April 2007.

Conceptual Understanding Sub-cell 11b

1. Sefton Council (2007) Coastal defence: report on the evolution of salt marsh on the Sefton coast. August 2007. Report prepared by M Newton, G Lymbery and P Wisse.

2. Sefton Council (2007) Coastal defence: Report on Coastal Erosion predictions for Formby Point, Formby, Merseyside. Parts 1 and 2. July 2007. Report prepared by G Lymbery, P Wisse and M Newton. Available online at: http://www.sefton.gov.uk

3. Shoreline Management Partnership (1999) Sub-cell 11b: Formby Point to River Wyre. Context Report. June 1999.

4. Coastal Engineering UK Ltd (2007) Local Monitoring Report 2005/6: Coastal process review 2005. Report produced for Sefton Council January 2007, revised April 2007.

5. Pye K. and Van der Wal D. (2001) Historical Trend Analysis (HTA) as a tool for long-term morphological prediction in estuaries. Presented as Annex 2 of the Sandwinning at Horse Bank, Southport Public Enquiry. July 2001.

6. Halcrow (2004) Ribble Estuary Managed Realignment Study. Report produced by Halcrow for the Environment Agency. July 2004, 69pp + figs.

7. Van der Wal D. Pye K. and Neal A. (2002) Long-term morphological change in the Ribble Estuary, northwest England. Marine Geology 189, 249-266.

8. Pye K. and Van der Wal D. (2000) Historical Trends Analysis (HTA) as a tool for long-term morphological prediction in estuaries. In: Estuaries research Programme, Phase 1 - Emphasys Consortium. Modelling Morphology and Process. Final Report. MAFF Contract CSA 4938, MAFF Project FD1401. Paper 14.

9. HR Wallingford (2001) Sediment transport and the effects of sand extraction. Fylde Shoreline, Lancashire. Stage 3: Modelling Phase II. Report EX4352.

10. Coastal Engineering Consultancy Services (2001) Coastal and River Defence Strategy Plan: Sediment Transport Regime. Report prepared for Wyre Borough Council.

11. Halcrow (2002) Futurecoast. CD produced as part of the Futurecoast project for Defra.

12. Wyre Borough Council (2004) Wyre Flood and Coastal Defence Strategy Plan. 62pp.

13. Coastal Engineering UK Ltd (October 2009) Blackpool and Fylde Baseline Local Monitoring Report 2008/09: Draft Report. Report produced for Blackpool Council October 2009.

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Conceptual Understanding Sub-cell 11c

1. Coastal Engineering Consultancy Services (2001) Coastal and River Defence Strategy Plan: Sediment Transport Regime. Report prepared by Coastal Engineering Consultancy Services for Wyre Borough Council.

2. Produced by Wyre Borough Council. Found at: http://www.wyrebc.gov.uk/Page.aspx?PvnID=58210&PgeID=192&BrdCb=1-1447-1448

3. Halcrow (2002) Wyre Strategy Study. Report produced by Halcrow for the Enviroment Agency.

4. Shoreline Management Partnership (1999c) Sub-Cell 11c: River Wyre to Walney Island Shoreline Management Plan. Report produced by Shoreline Management Partnership for Morecambe Bay Shoreline Management Plan Partnership.

5. Motyka J.M. and Brampton A.H. (1993) Coastal Management: Mapping of littoral cells. HR Wallingford Report SR 328. 102pp.

6. Halcrow (2004) Lune Estuary Habitat Management Study. Lune Estuary Habitat Management Plan. Report produced by Halcrow for Lancaster City Council. August 2004, 46pp + Figs.

7. Halcrow (2002) Futurecoast. CD produced as part of the Futurecoast project for Defra.

8. French P.W. and Livesey J.S. (2000) The impacts of Fish-Tail Groynes on Sediment Deposition at Morecambe, North-West England. Journal of Coastal Research. 16. 3. pg 724-734.

9. Atkins (2000) Walney Island Coastal Management Strategy. Report produced by Atkons for Barrow Borough Council.

10. Bullen and Partners Consulting Engineers (1986) Borough of Barrow-in-Furness, Preliminary Coastal Survey, May 1986. Report produce by Bullen and Partners Consulting Engineers for Barrow in Furness Borough Council.

11. Bullen Consultants Ltd (1998) St Bees Head to Earnse Point Shoreline Management Plan, Volume 1 - Core report.

12. Yasin A.Y. (1991) Sedimentary deposits, Processes, Sources and Evolution of the sandy, macrotidal Duddon Estuary, Northwest England. PhD Thesis, University of Reading. 438p.

13. ABPmer (2006) Morecambe Bay Strategy Scoping Study. Report produced for Lancaster City Council.

14. ABPmer (2003) Roa Island Shorelink: Sustainability Study. Report produced by ABPmer for Barrow Borough Council. Report + Figs + Apps. Available online from: http://www.barrowbc.gov.uk/default.aspx?page=1230

Conceptual Understanding Sub-cell 11d

1. Halcrow (2002) Futurecoast. CD produced as part of the Futurecoast project for Defra.

2. Bullen Consultants (1998) St Bees Head to Earnse Point, Isle of Walney Shoreline Management Plan. Volumes I to III. November, 1998.

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3. JBA Consulting (2005) Coastal Erosion Studies. Final Report, February 2005. Report produced for by JBA Consulting Copeland Borough Council.

4. Jung-Suk O. (1999) The Migration and Accumulation of Radionuclides in the Ravenglass Estuary, Cumbria, UK. Unpublished PhD Thesis. University of Southampton.

5. Assinder D.J. Kelly M. and Aston S.R. (1985) Tidal variations in dissolved and particulate phase radionuclide activities in the Esk Estuary, England and their distribution coefficients and particulate activity fractions. Journal of Environmental Radioactivity 2, 1-22.

6. Bullen Consultants (1995) St Bees Promenade. Emergency Repairs to Northern End. November 1995.

7. Coastal Engineering UK Ltd (October 2009) Baseline Local Monitoring Report 2008/09: Final Report. Report produced by Coastal Engineering UK Ltd for Copeland Borough Council November 2009.

Conceptual Understanding Sub-cell 11e 1. Halcrow (2002) Futurecoast. CD produced as part of the Futurecoast project for Defra. 2. Coastal Engineering UK Ltd (2008) Copeland Borough Council coastal defence monitoring survey March 2008. Report produced by Coastal Engineering UK Ltd for Copeland Borough Council 3. Bullen Consultants Ltd (1998) St Bees Head to River Sark Shoreline Management Plan. Volume 3: Supporting Information. Data Collation, Analysis, Interpretation, Objective setting. 4. Bullen Consultants Ltd (1998) Allonby Bay Coastal Defence Study. 5. Royal Haskoning (2004) Maryport Harbour Flood and Coastal Defence Scheme: Health and safety file.

6. Royal Haskoning (2005) Silloth to Skinburness Beach Management Plan. Monitoring Programme Report 2004.

7. Coastal Engineering UK Ltd (October 2009) Baseline Local Monitoring Report 2008/09: Final Report. Report produced for Copeland Borough Council November 2009.

8. Coastal Engineering UK Ltd (2009) Allerdale Baseline Local Monitoring Report 2008/09: In preparation. Report produced for Allerdale Borough Council.

9. HR Wallingford (2005). Dumfries and Galloway Shoreline Management Plan. Report produced by HR Wallingford for Dumfries and Galloway Council and Scottish Natural Heritage. Available on line at: http://www.dumgal.gov.uk/index.aspx?articleid=7

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APPENDIX A

Sub-cell 11a: Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast Sub-Cell 11a Future offshore energy developments, e.g. offshore windfarms, and potential impacts 3 wide on sediment (including impact of scour protection) Aggregate extraction within Liverpool Bay 3 Tidal barrages and lagoons (e.g. Mersey Tidal Power) (L15) 2,3 Evolution of offshore sand banks and channels (Dee and N Wales) 3 Sediment budgets (including rates, sources, sinks, direction) 1,2,3 Sediment transport along the North Wales frontage Better understanding of littoral drift behaviour Role of Liverpool Bay as a sink Accuracy of flood risk maps 2 Extreme water level predictions 1 Better definition of tidal current behaviour 1 Expansion of inshore wave climate datasets to cover the lower part of the Dee 1 Estuary (L16) Great Orme Western boundary of the SMP - influence of Great Orme headland on sediment 4 transport (L3) Llandudno The issue of fluvial and pluvial drainage from behind coastal defences increasing flood 2 risk

Sub-cell 11a: Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast Great Orme Mobility of the lower beach (composed of cobble and boulders) (L4) 4 to Rhos-on- Current and future influence of Constable Bank, offshore of Penrhyn Bay 1,4 Sea The linkage (if any) between Constable Bank and onshore transport of sediments during certain climatic conditions (L8) Onshore-offshore sediment transfer (L6) 3 By-passing of material around Little Orme (L5) 3 Rhos-on-Sea Source of the shingle beaches and mobility of sub-tidal shingle deposits (L7) 4 to Point of Onshore transport of sand 4 Ayr Future beach recharge requirements 2 Reinstatement of drift following intervention along the Towyn embankment (L13) 3 Role of the ridge and runnel system - possibility of wave focusing (L9) 3 Effects of Afon Clwyd discharge (L11) 3 Influence of Talacre dunes erosion/accretion on sediment transport behaviour (L12) 3 Dee Estuary Role of Dee estuary as a sediment sink. 4 Mobility and future change of the banks and channels in the outer Dee estuary and 4 influence on shoreline evolution (L20) Future evolution of the Dee Estuary approaches bank and channel system east of the 1 Afon Clwyd and the propagation of East Hoyle sandbank across the north Wirral

Sub-cell 11a: Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast shoreline (L14) Development of the Mid Hoyle channel taking over from the Welsh channel / 3 Development of the East Hoyle sandbank pushing the channel onto the Wirral coastline (L21) Influence of the Dee estuary on the adjacent open coastlines 4 Sediment transport across the mouth of the Dee 4 Onshore movement of sediment into estuaries 3 Impact of man’s activities on current and future estuary functioning (L19) 3 Effects of channel dredging of Welsh Channel - Port of Mostyn (L10) The medium to long term effects of recent developments between Oakenholt and Hawarden Bridge on the Dee Estuary regime (L17) Modelling of Joint wave and water levels in outer Dee Estuary (L18) 3 Future morphological evolution of estuaries under SLR 3 Wirral Current and future influence of the Dee and Mersey, and associated banks and 4 channels, on evolution of this coastline Accretion rates along the frontage 2 Land contamination issues 2 Mersey Dredging of Mersey Estuary 3

Sub-cell 11a: Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast Estuary Proposed Mersey Crossing 3 Future development of the Port of Liverpool (including dredging) (L24) 3 Impact of man’s activities on current and future estuary functioning (L22) 3 Sediment transport across the mouth of the Mersey (L23) 3 Sefton Coast Current and future influence of the Mersey and Ribble, and associated banks and 4 channels, on evolution of this coastline. Future vulnerability of the River Alt area (L32) 3 Continued growth of the offshore banks and impact of this on the coastal evolution 4 (L25) The correlation (if any) of Formby Bank morphology changes with deposition of 1 dredging arisings at Jordan’s Bank (L33) Impact of training walls and subsequent dredging and spoil dumps on the transport 4 regime (L26) 3 Accretion rates at Crosby 2 Land contamination at Blundellsands 2

Existence of a drift divide at Formby Point (L27) 3,4 Erosion of Formby Point 2

Sub-cell 11a: Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast Shoreline exposure changes to be expected with the ongoing retreat of Formby 1 Point (L28) Define the limits of recession that could be reached at Formby Point, due to changes in natural process behaviour and associated effects of human interference e.g. disposal of River Mersey and Ribble dredging arisings, sewage sludge disposal, River Mersey training, etc. Role of the ridge and runnel system - possibility of wave focusing (L29) 3,4 Impact of changes in shoreline orientation (moving from a curved plan-shape to a 4 straighter plan-shape) on the sediment transport regime (L28) Influence of dune erosion/accretion on sediment transport behaviour (L31) 3 Impact of sand mining at Horse Bank 4 Onshore transport of sediment (L30) 3

Sub-cell 11b Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Sub-Cell 11b Extreme water level predictions, with specific emphasis on conditions in the Ribble Estuary 1 wide (L40) Better understanding of tidal current behaviour along the west and north facing coasts of 1 the Fylde Peninsula

Better understanding of littoral drift behaviour identifying quantities 1 Ridge and runnel system (Sefton and Fylde) and the affect on the sediment budget and 3 shoreline response

Accuracy of flood risk maps 2 Ribble Role of estuary as a sediment sink (L34) 4 Estuary Impact of man’s activities, including maintenance of training works on current and future 4 estuary functioning (L35) Contamination risks 2 Mobility and future change of the banks and channels in the outer estuary and influence on 4 shoreline evolution (L36)

Influence of the estuary on the adjacent open coastlines (L41) 4 Sediment transport across the mouth of the Ribble (L37) 4 Future response to sea level rise, e.g. capacity for further infilling of the estuary (L38) 4 Impact of sand mining at Horse Bank and Salter’s Bank (L39) 4

Sub-cell 11b Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Impacts of managed realignment 2 Physical and/or numerical modelling of the Ribble estuary to be carried out to provide the 1 best possible estimate of likely future estuary changes and to define the implications for future coastal defence provision

Fylde Coast Influence of the Ribble, Wyre Estuary and Morecambe Bay, and associated banks and 4 channels, on evolution of this coastline

Impact of sand mining at Salter’s Bank 3,4 Influence of the deep-water channel of Lune Deep, which is thought to afford some 4 protection to the north Fylde Coast (L42) Dune behaviour (erosion / accretion) 2 Role of the banks offshore of Fleetwood (L43) 4 Existence of a flow divergence offshore of the Blackpool frontage (L44) 4 Existence of a littoral drift divide in the region of Cleveleys (L45) 4 Understanding the source of cobbles observed along the Cleveleys frontage 3

Impact of coastal structures (Wyre and Blackpool) 3 Fleetwood Port (navigation channel dredging and disposal in the Lune Deep) 3

Key: = Regional Tide and Sediment Modelling; = Influence of Offshore Banks; = Estuary Morphodynamics; = Morphodynamics of Morecambe Bay.

Sub-cell 11c Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Sub-Cell 11c Role of skears (scars) in diffracting waves (L47) 4 wide Evaluation of how skears could be used as coastal defences if reinforced (L47) 1

Movement of sediment within Morecambe Bay 4 Better understanding of littoral drift behaviour identifying quantities 1 Large scale sediment budget uncertain - local studies have been undertaken, but no large- scale assimilation of data (L48) 3

Role of Morecambe Bay as a sediment sink (L48) 4 Future response of Morecambe Bay to sea level rise (L48) 4 Impact of man’s modifications (railway, reclamation) 4 Susceptibility of coast to storm surges 4 Extreme water level predictions, with specific emphasis on conditions in the approaches to 1 the three main estuaries (Kent, Leven and Lune)

Better understanding of tidal current behaviour along the whole cell 1 An investigation of sea bed and water levels within the Lune, Kent and Leven estuaries and 1 the Walney Channel

Accuracy of flood risk maps 2 Reasons for recent saltmarsh erosion - possible linkage to changes in channel form 3 resulting in a bore-effect at later stages of the tide. Coastal squeeze losses (L49)

Sub-cell 11c Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Influence of estuaries on adjacent shorelines (L48) 3 Changes in flood and ebb channels and banks, and their influence on shoreline evolution, 4 both in terms of their position and also their form (i.e. width and depth) (L46)

No bathymetry of the Lune Deep 3

River Wyre Historical channel shift for Wyre 3 to Heysham Protective influence of Sunderland Point and future erosion rates 2 Heysham to Influence of the Leven and Kent and associated channels and banks (L51) 4 Roa Island Influence of Walney Island and potential impact should the spit on Walney Island erode 4 (L52) Influence of Heysham harbour and approach channel (L50) 3 Changes in behaviour at Silverdale and Grange over Sands (L53) 3 Better understanding of estuary dynamics, bank and channel changes and shoreline 1 evolution within the Kent and Leven Estuaries

Contamination issues at Ulverston 2 Cliff erosion rates 2 Walney Island Existence of littoral drift divide along the central section of Walney Island (L55) 3,4 Feed of sediment to and from both Duddon Estuary and Morecambe Bay (L55) 4

Sub-cell 11c Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Source of sediment and possibility for onshore movement of beach material (L55) 4 Possibility of a permanent breach being maintained by tidal flows between west and east 4 coasts (L56) Issues relating to role of historical land fill sites (L54) 2,3 Erosion rates 2,3 Duddon Sediment linkages with Walney Island 4 Estuary Role of estuary as a sediment sink (L57) 4 Potential responses to implementation of Managed Realignment (L57) 3 Impact of man’s activities on current and future estuary functioning (L57) 4 Mobility and future change of the banks and channels in the outer estuary and influence on 4 shoreline evolution (L57) Influence of the estuary on the Walney Island and adjacent open coastline to the north 4 (L58) Sediment transport across the mouth of the Duddon (L57) 4 Onshore movement of sediment 4 Future response to sea level rise, e.g. capacity for further infilling of the estuary (L57) 4

Sub-cell 11d Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 3= CETaSS & CERMS CETaSS JPS Other Workshop 4= Futurecoast Sub-Cell 11d Determination of sediment pathways and fluxes for the eastern Irish Sea by using 1 wide numerical modelling techniques supported by available field data to enable a sediment budget to be determined for the coast 3 Limited knowledge of direction and magnitude of sediment drift along this frontage (L59) Numerical model to determine nearshore wave conditions and sediment transport 1 arising from individual storms and estimate annual aggregate conditions Quantification of erosion rates along the coast 1 Direction of sediment drift along this frontage 4 Sediment budget (including transport, sources, sinks, availability, etc.) 3

Change in MSL from a historical fall to a possible accelerated rise in the future 3

Role of skears (scars) in providing localised protection to the shoreline 3,4 Onshore-offshore sediment transfer 4 Accuracy of flood maps 2 Haverigg to Influence of Duddon and Ravenglass estuaries 4 St Bees Head Erosion rates 2 Ravenglass Evaluation of the loss or gain of saltmarsh and mud/sandbanks within the estuaries 1 Estuary Dune behaviour (Drigg and Eskmeals spits) 2 Complex

Key: = Regional Tide and Sediment Modelling; = Influence of Offshore Banks; = Estuary Morphodynamics; = Morphodynamics of Morecambe Bay.

Sub-cell 11e Uncertainties in present understanding Area Issue / Uncertainty Reference Monitoring / studies that provide 1= SMP1 data/information to address uncertainties 2= SMP2 CERMS CETaSS JPS Other 3= CETaSS & Workshop 4= Futurecoast Sub-Cell 11e Determination of sediment pathways and fluxes for the eastern Irish Sea by using 1 wide numerical modelling techniques supported by available field data to enable a sediment budget to be determined for the coast

Limited knowledge of direction and magnitude of sediment drift along this frontage 3 (L62) Numerical model to determine nearshore wave conditions and sediment transport 1 arising from individual storms and estimate annual aggregate conditions Quantification of sediment transport erosion rates along the coast 1 Evaluation of the loss or gain of saltmarsh and mud/sandbanks within the estuaries 1 (Solway Firth and Moricambe Bay) Impacts of offshore windfarms (Robin Rigg) 3

Potential tidal barrage 3

St Bees Head Influence of Solway Firth and associated banks and channels on the adjacent 4 to The Grune shoreline (L60) Longer term influences of interventions including harbours at Whitehaven, 3 Workington, Maryport and Silloth and coastal defences (L61)

Cliff erosion rates 2 Impacts of erosion of Dubmill Point on adjacent frontages to the north 2

The Grune Detailed mechanisms for the geomorphological sustenance of The Grune should be 1 identified, in particular the effect of the restriction of sediment supply from the Silloth - Skinburness coast defence works

Solway Firth Sediment dynamics within the Solway Firth (channels / banks, sediment budget) (L60) 3,4 Changes in the orientation and form of banks and channels within Solway Firth 4 Future response of Solway Firth to sea level rise (L60) 4