coastal trends report...1.3 beach topographic profile data the environment agency has collected...

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Coastal Trends Report

Essex

(Subcell 3d - Harwich to Canvey Island)

RP008/E/2008

July 2008

ii

We are the Environment Agency. We protect and improve the environment and make it a better place for people and wildlife.

We operate at the place where environmental change has its greatest impact on people’s lives. We reduce the risks to people and properties from flooding; make sure there is enough water for people and wildlife; protect and improve air, land and water quality and apply the environmental standards within which industry can operate.

Acting to reduce climate change and helping people and wildlife adapt to its consequences are at the heart of all that we do.

We cannot do this alone. We work closely with a wide range of partners including government, business, local authorities, other agencies, civil society groups and the communities we serve.

Published by:

Shoreline Management Group Environment Agency Kingfisher House, Goldhay Way Orton goldhay, Peterborough PE2 5ZR Email: [email protected] www.environment-agency.gov.uk © Environment Agency 2008 All rights reserved. This document may be reproduced with prior permission of the Environment Agency.

Further copies of this report are available from our publications catalogue: http://publications.environment-agency.gov.uk or our National Customer Contact Centre: T: 03708 506506

Email: [email protected].

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mailto:[email protected]

Glossary Accretion The accumulation of sediment on a beach by the action of

natural forces or as a result of man-made artificial structures Bathymetry The topographic relief of the seabed Chainage The distance along a topographic survey transect line,

measured in metres Chart Datum The level to which all soundings on a marine navigational chart

are based Erosion The loss of material from a beach by the action of natural

forces or the result of man-made artificial structures interfering with coastal processes

FCP Foreshore Change Parameter Foreshore The area of beach lying between high water and low water Foreshore rotation Foreshore steepening or flattening resulting in the

convergence or divergence of high and low water marks Longshore drift Movement of sediment along the shoreline MHWS level of Mean High Water Spring tides MHWN level of Mean High Water Neap tides MLWN level of Mean Low Water Neap tides MLWS level of Mean Low Water Spring tides MSL Mean Sea Level Ordnance Datum The mean sea level ( as derived from 6 years of observation at

Newlyn, Cornwall) used as a datum for calculating the absolute height of land on official British maps.

Recharge A management practise of adding to the natural amount of

sediment on a beach with material from elsewhere. This is also known as beach replenishment, nourishment or feeding

SMP Shoreline Management Plan

Coastal Trends Analysis……………………………………………………..........

1.0 INTRODUCTION 1.1 PURPOSE AND APPLICATION 1.2 BACKGROUND 1.3 BEACH TOPOGRAPHIC PROFILE DATA 1.4 ANALYSIS METHODOLOGY 1.5 FUTURE OUTPUTS 2.0 ESSEX (SUB-CELL 3d) COASTAL TRENDS 2.1 INTRODUCTION 2.2 GENERAL DESCRIPTION – HARWICH TO CANVEY ISLAND 2.3 OUTLINE OBSERVATIONS

2.3.1 Harwich to Hamford Water 2.3.2 The Naze (Stone Point) to Lee-over-Sands (Colne Point)

2.3.3 Mersea Island

2.3.4 Dengie Flat (Bradwell Peninsular to Ray Sand)

2.3.5 Maplin Sands (Foulness Point to Havengore Head)

2.3.6 Southend-on-Sea (Haven Point to Leigh-on-Sea)

3.0 GRAPHICAL VIEW OF RESULTS APPENDIX 1 – DETAILED RESULTS APPENDIX 2 - REFERENCES

Map 1 – The Anglian Coast

copyright and/or database rights 2008. All rights reserved.© Crown copyright and database rights 2008 Ordnance Survey 100024198. © Environment Agency

1.0 Introduction

1.1 Purpose and application This report is intended as a tool to assist coastal managers in a variety of their functions including; strategic planning, capital engineering works and maintenance programmes. In addition to this the report will be of assistance with general education and awareness raising of coastal issues. The outputs will also aid the determination of beach health parameters within NFCDD (National Flood and Coastal Defence Database).

1.2 Background The Anglian coastline stretches from Grimsby near the mouth of the River Humber to Canvey Island on the northern side of the outer Thames estuary (Map 1). With a total length of approximately 470km the coast is a diverse mixture of dune fronted flood plains, shingle barrier beaches, saltmarsh and soft cliffs. There are no major geological ‘hard rock’ coastal areas and thus significant proportions of the coast are vulnerable to marine flooding and erosion. This is likely to be compounded by climatic change and sea level rise in the future. In order to reduce the impacts of this upon the built and natural coastal environment much investment has been made in both hard and soft engineering solutions over the last century. This has resulted in significant proportions of the coast being artificially held to prevent the loss of development and infrastructure located in vulnerable areas. The Environment Agency has undertaken regular strategic coastal monitoring of the Anglian coast since 1991. The rationale behind the programme is to assist the implementation of appropriate and sustainable works on the coast, whether this be works undertaken by the Agency for the purpose of flood risk management or works undertaken by various maritime district council partners for erosion reduction purposes. An additional output from the monitoring programme is the assessment of coastal dynamics to inform long term strategic plans for the coastline. The vehicle for this is the Shoreline Management Plan (SMP) process, which is currently being reviewed along the entire Anglian coast. The Anglian Coastal Monitoring programme collects a variety of data including; Annual aerial photographs Annual topographic beach surveys (winter and summer) at 1km intervals Bathymetric surveys (extension of beach survey lines out to approximately 10

metre depth offshore) Continuous wave and tide recording (nearshore and offshore)

In addition to this, in-depth monitoring addresses specific sea defence scheme requirements at a variety of locations along the coast. At the time of writing, the Anglian monitoring programme has begun phase VII, which includes a suite of five offshore, and twenty nearshore continuous wave and tide recorders. Various reports based upon the data collected over the years have been produced. Until now the work undertaken has been unable to assess any significant trends in the data due to the insufficient length of time over which the data has been collected. However, the Agency now possesses sixteen years of beach topographic data and it is therefore possible to analyse these to determine initial indicators of longer-term trends. Data collected in the future can be readily added to this analysis to further ascertain the validity of the trends.

1.3 Beach topographic profile data The Environment Agency has collected beach topographic profile data at 1km intervals along the coast since 1991. Profiles are taken twice yearly in summer and in winter. The most recent set of available data means that there is now a continuous record of beach levels spanning sixteen years. Generally the area of interest is the average rate of beach erosion or accretion along the coast. In addition to this, gradual change to the gradient or steepness of the beach is of particular interest to coastal managers. The analysis of trends in beach morphological behaviour may have significant impacts upon coastal management decisions in the future. Artificially defended beaches that are experiencing erosion and steepening trends may prove to be increasingly difficult and expensive to maintain. Even with maintenance, the structures may fail because of inadequate structural support or ground movements from diminishing quantities of beach material and subsequent beach platform loss. However, it is not the intention of this report to ascertain such issues at a local scale. The ongoing revisions of the Shoreline Management Plans (SMPs) and Coastal Strategic Studies, which are currently being compiled along the Anglian coast, are the appropriate vehicle for this assessment. The length of the Anglian coast means that there are over 400 topographic profiles that have been collected over the years. For the purposes of regional strategic coastal management, the entire UK coast has been divided up into sediment cells and sub-cells (HR Wallingford, 1994 & Defra, 2006). These are individual discrete sections of the coast that are considered to be independent from each other in terms of coastal processes. The relevant sections on the coast are: - Flamborough Head to Donna Nook Sub-cell 2a+b1*

Donna Nook to Gibraltar Point Sub-cell 2c Gibraltar Point to Old Hunstanton Sub-cell 2d Old Hunstanton to Kelling Sub-cell 3a Kelling to Lowestoft Ness Sub-cell 3b Lowestoft Ness to Felixstowe Sub-cell 3c Harwich to Canvey Island Sub-cell 3d These boundaries are convenient divisions for the separation and publication of the results of the trends analysis reports.

1.4 Analysis methodology The profile data presented in this report is in the form of beach level analysis. The data was analysed using a function of ‘SANDS’ software (1). Tidal levels and conversions from Chart Datum to Ordnance Datum were kindly supplied by Proudman Oceanographic Laboratory from their ‘POLTIPS’ software (2). Generally, the accepted definition of the foreshore is the intertidal region between the highest and lowest tide level. In this report the area between the MHWN (Mean High Water Neaps) and MLWN (Mean Low Water Neaps) level is used2**.

* The first SMP review for this section of coast will encapsulate the coast from Flamborough Head to Gibraltar Point. Only that part of the coast south of the Humber is within the Anglian region. ** For some profiles where there are limited data at MLWN the data from MSL (Mean Sea Level) is utilised.

Figure 1 demonstrates the principle of beach profile change over time along with changes to beach gradient. Along certain stretches of coast where seawalls or other structures constrain the landward movement of the coast, beach volumetric change may be of interest. This is particularly relevant where artificial beach nourishment is undertaken. In other areas, where long frontages are unconstrained by linear defences the quantification of beach volumetric change is of less importance.

Figure 1 – Conceptual diagram of a beach profile showing shoreline advance/retreat and

foreshore change parameter

Figure 2 demonstrates how the analysis was performed and a trend is obtained. The example used in Figure 2 is from an eroding beach, which is retreating with an average trend of -3.86m/yr. However, in any single year the actual erosion observed varies considerably. For example between 1996 and 2000 very little erosion occurred, whereas between 2000 and 2001 the beach retreated by almost 20m.

Figure 2 – Suite of coastal profiles after SANDS beach level analysis with linear regression of MSL giving annual trend (data gaps are due to certain profiles not extending down to MLW

level) An important factor in coastal risk management policy decision making is foreshore steepening. A wide flat beach can dissipate incoming wave energy much more readily than a narrow steep beach. Using historical Ordnance Survey data, Taylor et al (2004) concluded that 61% of the coastline of England and Wales had steepened since the first OS County Series Survey published between 1843 and 1901. Of the remainder 33% had flattened and 6% experienced no rotational movement. Earlier work by Halcrow (1988) used the method to assess the Anglian coast to assist in the development of a management strategy for the Environment Agency’s coastal flood defence predecessor, Anglian Water. This study concluded that 78% of the Anglian coast had experienced steepening between the mid 1800’s to the 1970’s. The analysis in this report uses a similar methodology to that of Taylor et al (2004) and although the length of time covered in this report is an order of magnitude less than their data-set, the data utilised here is likely to be of much greater accuracy. The positional accuracy quoted in Taylor et al for OS maps are +/-5m for pre-1945 County Series Maps and +/-3.5m for post-1945 National Grid mapping. Whereas the accuracy of the Anglian Coastal Monitoring profiles is +/-0.05m vertical and +/-0.02m horizontal. Changes in the gradient of the beach between MHWN and MLWN are expressed in the form of the ‘Foreshore Change Classification system’ (Halcrow, 1988) shown in Table 1. Positive Foreshore Change Parameter (FCP) values indicate a beach system advancing seaward and negative values show a system retreating landward. The individual FCP numbers indicate either flattening, steepening or no rotation. As no pair of MHWN and MLWN trendlines were likely to possess exactly the same gradient, every profile could be described as either flattening or steepening. In order to eliminate insignificant rotational changes any change of less than 1.0% of the mean width of the foreshore was considered to be ‘no change’. In addition to this,

judgement was used where some apparent rotational changes were deemed to be unreliable due to high degrees of foreshore variability.

1.5 Future outputs Future updates of this report will include updated information on beach trends using the latest available profile data. In addition to this, the report may include extended analysis utilising other data sets collected by the Shoreline Management Group. Bathymetric surveys have been undertaken at 5 year intervals and this will be enhanced as part of the phase VII (2006-2011) monitoring programme. In addition to this, output from the wave and tide recording buoy deployments will be included. These reports will support and inform the move towards a ‘risk-based’ monitoring programme for 2011 and beyond.

Table 1 – Foreshore change classification system (adapted from Halcrow, 1988). The change is indicated in red.

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2.0 Essex (sub-cell 3d) coastal trends

2.1 Introduction The Essex study area for this report extends from Harwich on the southern bank of the Stour to Southend-on-Sea on the northern bank of the Thames. [Canvey Island has not been included in this analysis as profiles here have been regarded as estuary (Thames) and not coastal]. Essex has an unusual coastline formed by a series of interlinked estuaries (the Roach/Crouch, Blackwater, Colne and Hamford Water) giving rise to relatively discrete units of open coast in between – the Tendring, Dengie and Foulness peninsulars. Much of the coastline is low lying and protected by earth/clay flood embankments with sea facing revetment works or sea walls together with groynes. The highly developed Tendring peninsular is characterised by long term shore recession with groyned sand and shingle beaches backed by sea walls. At Jaywick, a number of shore defence works have taken place between West Clacton and Cocketwick to try to keep longshore drift to a minimum, reduce beach scour and subsequent erosion in front of the existing 1930s sea wall. The original scheme at Jaywick (1986 – 1988) consisted of four rock armoured fishtail breakwaters plus beach recharge and was only the second scheme of its kind to be implemented in Britain. Following construction, however, continued beach loss between the breakwaters confirmed that the fishtails had been spaced too far apart. This lead to the instigation of the second Jaywick scheme in 1999 which introduced a further fishtail groyne, offshore breakwater and continued beach recharge. Ongoing works will continue in 2008/2009 to add an additional breakwater adjacent to Brooklands which had been omitted from the second scheme. The adjacent frontage at Seawick – to the west of Cocketwick breakwater – has seen new sea defences established in 1998 consisting of a series of shore normal rock groynes together with a shore parallel rock groyne to replace an old groyne system. Further west of here the beach continues to erode to the sea wall. Works to improve the 2.3km frontage to the Tendring and Holland sea wall were completed in 2001/2002. These sea defences protect properties and land in Holland-on-Sea and Frinton-on-Sea. Significant erosion rates along the cliffs at the Naze has led to several proposals for protection works to reduce cliff erosion by stabilising the beach fronting the cliffs. A rock hard point has been constructed at the southern end of the Naze and the beach material imported at the northern end to offset the effects of foreshore erosion. The cliffs at the Naze represent the only example of cliffs of any height in the county. They are a designated Geological SSSI and archaeologically significant due to their nationally important Pleistocene exposures which contain some of the first evidence of human occupation in this country. In additional to Tendring, Southend-on-Sea and Harwich represent the other developed areas along the Essex coastline and are characterised by sand/shingle beaches with groynes, backed by sea walls. Recharging of the beach to the east of

Southend Pier as far as Thorpe Esplanade in 2002 has created a new beach at Southend-on-Sea. The remainder of the coastal frontage is largely rural and supports agricultural land and some nationally and internationally important wildlife and conservation sites. On Dengie and Foulness the shoreline is largely artificial in nature due to a succession of sea wall enclosures and extensive reclamation of saltmarshes during the period 1650 to 1850. These low wave energy environments form rare examples of open coast marsh. The protected land here is lower than the saltmarsh on the seaward side of the embankments, with the large extents of saltmarsh and mudflats providing an important role in coastal defence and the first line of defence to the land, reducing the pressures on the embankments –- the formal flood defence. Thames lighter barges, now redundant, were introduced along sections of the Essex coast from the mid 1980s and sunk in the nearshore zone to reduce wave energy and help maintain the saltmarshes. These are located at two sections along the Dengie peninsular and also at Horsey Island in Hamford Water. The saltmarshes are amongst the most extensive in the country with the mudflats and drainage ditches at Maplin Sands forming the largest continuous intertidal area in Britain extending several kilometres offshore down to MLWS. Much of the saltmarsh areas are designated SSSIs –- Maplin Sands regularly supports around 130,000 waterfowl, ranking this site (along with the Thames estuary) fourth in the country. Major centres of tourism, leisure and recreation along the Essex coastline are located at Southend-on-Sea, Tendring (particularly Clacton-on-Sea and Walton-on-the-Naze) and at Canvey Island. Harwich is a predominantly industrial unit and has the second largest passenger port in the country. Fishing is a major industry – the most productive cockle beds in the UK are located at Maplin Sands. Oyster beds and winkle fisheries are also of significant importance. West Mersea supports the largest concentration of trawlers operating from the Essex coast. This study deals with the coastline only and does not analyse any data that has been collected further inland or along the estuaries. The Environment Agency has collected a total of 78 beach profiles along the Essex coastline at 1km intervals since 1991.

2.2 General description – Harwich to Canvey Island Figure 3, overleaf, shows the general results of the analysis, which are summarised in Table 2 below. Percentages are worked out from the total of 78 beach profiles along this section of coast. In addition, Figures 3 and 4 show the trends analyses split into two sections, between Harwich to Mersea Island and Dengie Flat to Southend-on-Sea respectively. This is to show with greater clarity the smaller variation in trends between Harwich and Mersea. Appendix 1 shows the names and general locations of the profiles.

No. Percentage Accretion 38 49

No Change (+/- 0.2m yr) 18 23 General Trend Erosion 22 28

Flattening 38 49 Steepening 20 26 No rotation 15 19

Foreshore Gradient

N/A+ 5 6 Defences#

3 72 92 Defences at

profile location No defences 6 8

Table 2 – general results of analysis

2.3 Outline observations The majority of the Essex coastline (92%# of profiles) is artificially held by defences. Along the developed sections of coast at Harwich, Walton-on-the-Naze to Jaywick and at Southend-on-Sea beaches are backed by concrete sea walls with groynes. Clay or earth embankments back the expanses of mudflat and saltmarshes at Dengie Flat and Maplin Sands. As a result beaches may have been unable to behave naturally (to a significant degree) and where applicable ‘roll back’ in response to natural processes. Of the 78 profiles along this stretch of coastline almost half (49%) of profiles show a general accretion trend over the last 16 years. Significant trends of accretion were apparent along the broad expanses of mudflats at Dengie Flat, Maplin Sands and Shoeburyness where the foreshore can extend several kilometres seaward of MHWS. Rotational changes here in the order of several tens of meters are regarded as insignificant although erosion/accretion trends of the foreshore are presented. Over a quarter (28%) of profiles showed some erosional trend of the foreshore. Significant erosion was observed at three main locations – the Naze, particularly at Stone Point at the tip of the Naze with erosion trends of -3m/yr; at Jaywick, adjacent to Brooklands where trends were -4.5m/yr (despite beach nourishment works); and on the east of Mersea Island with rates between -3.2 and -4.4m/yr.

+ Some profiles did not have sufficient MLWN data to determine a reliable FCP score. # This figure relates to actual long-shore structures at the location of the profile determined from 2006 aerial photography and National Flood and Coastal Defence Database (NFCDD).

The majority of profiles (49%) show a significant flattening trend of the foreshore and around a quarter (26%) show a foreshore steepening trend. Roughly one fifth of profiles have shown no change in the general trend and no change in rotation of the foreshore gradient. The following section offers a description of the results of the analysis as well as graphically showing the trends overlaid over a suite of aerial photographs that were taken during summer 2006. Unless stated otherwise all trends and rates expressed relate to changes on the foreshore i.e. on or between the MHWN and the MLWN levels. The descriptions are divided into six sections which broadly relate to the divisions concluded by Halcrow (1988). Mean annual longshore wave energy values for the entire study area were 0 – 500 kN/s except for the section of coast from Stone Point on the Naze to Holland-on-Sea where values increased to 500 – 1000 kN/s (Halcrow, 1988).

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2.3.1 Harwich to Hamford Water E1D1A – Harwich. No movement at MHWN. Small accretion trend at MSL and small erosion trend at MLWNs. Therefore, mean rate is no movement. Slightly steepened profile. MLWN lies 70 – 100 m offshore. Surveyed profile crosses groyne. E1D2 – Harwich. Insignificant trends at all levels. No movement. E1D3 – Smack. No movement at MHWN and MSL. Relatively modest erosional trend at MLWN of -0.4m/yr. Narrow beach has receded from c12m to c6m in width in period 1992 – 1997. Significant steepening profile. Beach lies in front of revetment. E1D4 – Middle Beach. Erosion at all levels, significant at MHWN (-3.1m/yr) and MLWN (-0.9m/yr) to give a mean erosional trend of -1.5m/yr. Profile shows a flattening trend. MLWN lies 120m offshore. Saltmarsh in front of clay embankment appears to have retreated in period 1992 – 2006 by approximately 27m. E1D5 – Long Bank. Small accretion trend at MHWN; erosional trend at MSL with little overall movement at MLWN. Mean trends are slightly erosional. Steepening trend in profile. E1D6 – Irlam’s Beach. Accretion trends at MHWN (0.7m/yr) and MLWN (2.2m/yr) with erosional trend at MSL to give significant mean accretion rate of 0.7m/yr and a flattening profile. MLWN lies 700m offshore. No structures at this location. Sand beach backed by saltmarsh. Aerial photos show that beach has accreted by c15m in the period 1992 – 2006. 2.3.2 The Naze (Stone Point) to Lee-over-Sands (Colne Point) E1C1 – Stone Marsh. Profile data shows variability but a strong erosional trend at MLWN of -4.5m/yr. MSL and MHWN show similar strong erosional trends of -2.5m/yr and -2.2m/yr respectively. Profile therefore shows a slight steepening trend. No embankment at this location. Analysis shows recession of c30m of MHWN and MSL. Aerial photography shows saltmarsh depletion of c12m between period 1992 – 2006. E1C2 – Stone Creek. Strong erosional trends of -3m/yr at both MHWN and MLWN. Slightly increased erosion at MSL. Saltmarsh is backed by clay embankment. No beach rotation. All levels have receded by c50m in the period Feb 1992 – Jan 2007 (aerials support this). Period of accretion in 2000/2001. E1C3 and E1C4A – The Naze. Steady erosional trends at all levels. MHWN (-1.4m/yr) showed slight accretion in 2000/2001 then continued steady erosion. E1C3 is backed by a clay sea wall with concrete slab revetment. E1C4A has no defences and aerials show a cliff recession of c23m between the period 1992 – 2006 (see Figure 6). E1C5A – Cliffs near the tower at the Naze. Slightly lower erosional trends of cliff recession than the rest of the Naze and lower erosional trend at MLWN (-0.4m) compared to MSL and MHWN (-1.2m). Analysis of aerial photos between 1992 and 2006 shows that the base of the cliff has retreated by 15m in this period (see Figure 7).

1992

2006

Figure 6 – a) Aerial photos at the Naze (E1C4A) showing cliff retreat of c23m in the period 1992 to 2006. b) Photo of cliff erosion taken a few meters north of profile location (2008).

© Environment Agency copyright and/or database rights 2008. All rights reserved.(Photo: Environment Agency)

1992 2006

Figure 7 – a) Cliff slumping at the Naze. At E1C5A the beach has retreated by c15m in the period 1992 – 2006. b) Photograph of cliff slumping just south of profile location (2008).

© Environment Agency copyright and/or database rights 2008. All rights reserved.

(Photo: Environment Agency)

E1C6 – Jubilee Beach. All levels show high variability. MHWN shows a sudden erosional trend around 1996/1998, but the overall trends shows no movement. Slight erosional trend at MSL and MLWN gives profile a steepening trend. Concrete recurved sea wall at this location. Overall, little mean rate of movement. E1C7 – Walton-on-the-Naze. Slight erosional trend at MHWN although showing high variability. Higher erosional trend at MLWN gives a slight steepening of profile. Profile is backed by sea wall and is between groynes. Mean rate of erosion trend is 0.2m/yr. E1B1 – Walton-on-the-Naze. High variability of lower beach at MLWN with a slight general trend of erosion. Stable MSL. Little movement of upper beach. No significant change in profile. E1B2 – Frinton-on-Sea. Moderate trend of accretion at MHWN and MSL (0.5m/yr and 0.6m/yr). Lower rates of accretion at MLWN giving mean rate of 0.4m/yr accretion trend. E1B3 – Frinton-on-Sea. Significant rate of accretion at MLWN of 10m/yr. Accretion rates at MSL and MHWN (0.2m/yr to 0.3m/yr) giving a flattening profile (aerials support this). Mean accretion rate is 0.5m/yr. E1B4 – Frinton Golf Club. No significant change in profile. Slight erosional trend at MSL. Profile crosses longshore groyne. E1B5A – Holland Gap. Steady accretion trends at MSL and MHWN of 0.4m/yr with an accretion jump at 1996 and again in 2002 after which levels remain stable. MLWN trends are highly variable. Rock armour placed at seawall. E1B6 – Holland Haven Country Park. Slight accretion trends at MSL and MHWN (0.3m/yr – 0.1m/yr). Profile shows steepening trend due to MLWN showing no overall movement (although data points are highly variable). Rock armour has been placed along sea wall here and shore normal rock groynes near the profile removed during the study period. E1A1S – Holland-on-Sea. No overall significant change in profile. Both MSL and MHWN have shown identical periods of erosion and accretion. Profile located between groynes and backed by piling. E1A1 – Holland-on-Sea. Rock armour added to sea wall between 1999 and 2000. Profile shows little overall change. No movement of MSL or MHWN. MLWN is variable but shows a steepening and eroding trend. E1A2 – Holland-on-Sea. No movement of MHWN. MSL and MLWN show accretion trend from 1996 which then drop off around 2001 to give slight erosional and steepening mean trend of change. E1A3 – Clacton-on-Sea. Rock armour placed along sea wall between 1992 – 1997. Profile shows strong accretional trend at MSL and MHWN with less accretion at MLWN to give a steepening profile. Accretion trends are largely due to distinct accretion jump in 1994 at MSL and MHWN. Thereafter trends are relatively stable and the stated mean trend may be misleading. E1A4 – Clacton-on-Sea. Groynes removed and toe piling put in between 1992 and 1997. Strong accretion trends at MSL and MHWN due to 5m jump from 1994 –

1998. Steepening of profile due to erosional trend at MLWN. Trends since 2004 are very stable with no movement for all levels. General rate of trend is no movement. E1A5 – South Clacton. Strong accretional trends at all levels. MLWN has a higher accretional trend to give a flattening profile which is backed by sea wall. Mean rate of accretion is 0.6m/yr. E1A6, E1A7, E1A8 – West Clacton to Jaywick. Trends for these profiles have been calculated from 1999 when an additional fishtail breakwater, shore parallel breakwater plus arm extensions to an existing fishtail breakwater along with beach recharge took place as part of the West Clacton to Jaywick Sea Defences. This was in addition to the original scheme of 1986 to 1988 when four fishtail breakwaters were constructed together with beach recharge. Pre-1999 trends showed significant erosion trends at all profiles. Post-1999 trends also showed strong erosion at all levels on all profiles (except MLWN on E1A7) since 1999. Mean rates of erosion are highest at E1A8 showing -4.5m/yr erosional trend (no rotation). E1A6 and E1A7 show -1.7m/yr and -1.6m/yr, with steepening and flattening respectively. E1A8 MHWN has returned to pre-1999 levels showing substantial erosion. E1A6 and E1A7 appear more stable at all levels although showing lower erosional trends than E1A8 (see Figure 8). E1A9 – Seawick. New Seawick defences were added in 1998 consisting of a series of shore normal rock groynes to replace old groyne system, plus reinforcement of a shore parallel rock groyne (Hutley’s platform) adjacent to this profile together with beach recharge. Moderate erosion trends at all levels. Beach has been eroding since 1998 but shows slight flattening. E1A10 – Seawick. Significant erosional trends at all levels of -1.2m/yr to -1.3m/yr at MSL and MHWN. Slower erosional trend at MLWN to give flattening profile. Progressive retreat at all levels showed big jump in 1997. Aerial photography suggests beach profile has retreated c20m in the period 1992 – 2006 (see Figure 9). E1A11 – Lee-over-Sands. No significant change in profile although slight accretion trends at all levels. Trends are calculated up to 2005 after which the data appears misaligned. E1A12 – Colne Point. Strong accretional trends at all levels particularly at MLWN to give flattening profile. No defences at this location. Mean accretion rate of 1.3m/yr. Dunes.

1992

2006

1992

2006

Figure 8 – West Clacton to Jaywick sea defences 1992 and 2006 along with location of profiles E1A6, E1A7 and E1A8. An additional breakwater is being introduced in 2008/2009 (dashed orange line) adjacent to Brooklands pictured below – the most westerly fishtail breakwater can be seen in the distance (2008).



1992

2006

Figure 9 – Seawick sea defences 1992 and 2006 along with location of profiles E1A9 and E1A10. Profiles show erosion at all levels. The beach pictured lies to the west of the last groyne midway between the two profiles and shows significant foreshore erosion (2008).



2.3.3 Mersea Island E2A1 – Cudmore Grove Country Park. Little movement at MHWN. Strong erosional trends at MSL and MLWN (-8m/yr) to give a mean erosional trend of -3.2m/yr. Immediately west of this profile are the remains of a polder site in front of the cliffs (Figure 10) and immediately north, a spit which protrudes into the Colne estuary (Figure 11). Between the period 1992 – 2006 the base of the spit has accreted just north of the E2A1 profile by c40m with erosion midway along the spit (c35m) and accretion at the distal end of the spit (by c50m). MLWN extends 500m offshore. E2A2 – Fen Farm Caravan Park. No defences at this location. Significant accretion trend of 8.5m/yr at MLWN with moderate erosion at MHWN (-0.9m/yr), which is more significant at MSL (-5.4m/yr). Mean rates are skewed here to show a mean accretion trend of +0.7m/yr. MLWN extends 1km offshore. E2A3 – Hall Farm Caravan Park. Little movement at MHWN. Steady erosion at MLWN and MSL to give mean trend of erosion at -1.9m/yr. Clay embankment with revetment has been extended alongshore in front of the caravan park since 1997. MLWN extends 500m offshore. E2A4 – Youth Camp. Moderate to significant erosion at all levels to give mean erosion trend of -4.4m/yr, the highest along Mersea Island (see Figures 12/13). MLWN extends 1km offshore. Essex block revetment on clay embankment since 1997. E2A5 – Waldegraves Farm. No movement. E2A6 – West Mersea. No movement at MHWN. Moderate erosion trend at MSL and MLWN. MLWN extends 325m offshore. Rock armour revetment. Figure 10 – Cliff erosion adjacent to profile E2A1 showing remains of polder site on left (2008).


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Figure 12 – Sea defences adjacent to the Youth Camp, 1992 and 2006, near profile E2A4. Mean erosion trends here of -4.4m/yr are the highest along Mersea Island and amongst the highest along the entire Essex coastline. The locations of photographs a, b and c, displayed on the 2006 aerial, are shown in Figure 13.



a

c b

Figure 13 – a) View looking eastwards towards E2A4 (dashed orange line) where the most significant erosion trends occur along Mersea Island, b) Revetment works running adjacent to the Youth Camp looking west and c) beach erosion is occurring where the defence line stops, looking east (2008).


(Photo: Environment Agency) (Photo: Environment Agency)

2.3.4 Dengie Flat (Bradwell Peninsular to Ray Sand) E2A15 – Bradwell Peninsular. Lighter barges placed on profile in late 1980s at 240m chainage and not always shown in profile (Figure 14). No movement at MHWN with slight accretion trend at MLWN, slight erosion trend at MSL to give mean rate of trend as no movement. MLWN extends 400m offshore.

Figure 14 – Lighter barges at E2A15 with embankment in foreground (2008). E3E1 – St Peter’s Flat. Profile shows strong erosional trend at MHWN of -3.4m/yr compared to significant accretion trends at MSL and MLWN (between 13.8m/yr to 14.5m/yr). MLWN lies 1.4km offshore. Saltmarsh and mudflats on seaward side of embankment. Aerials indicate that saltmarsh extent has receded since 1992 by c50m. E3E2 and E3E3 – Dengie Flat. Profiles show relatively moderate erosion trend at MHWN with significant accretion trend at MSL and MLWN to give mean accretion rates of 6.6m/yr and 9.5m/yr respectively. MLWN lies 1.5 – 1.8km offshore. Aerials indicate that saltmarsh extent has receded since 1992 by c24km at both locations. E3E4 – Dengie Flat. Lighter barges placed on profile in early to mid 1980s at 600m chainage. These are usually shown in the profile but not always. They have skewed the MHWN accretion trend to 38.6m/yr which should be disregarded (see Figures 3 and 5). Moderate accretion trend at MSL with significant at MLWN. MLWN lies 2.3km offshore. Extent of saltmarsh appears to have accreted slightly on seaward side of embankment corresponding with midway along section of lighter barges. E3E5 – Dengie Flat. Slight accretion trend at MHWN. MSL shows moderate accretion trend with significant accretion trend at MLWN of 39m/yr. MLWN lies 2.5km offshore. Aerials indicate extent of saltmarsh has receded by c10m since 1992. E3E6 – Dengie Flat. Moderate to significant retreat of MHWN of -2.1m/yr and MSL -3.5m/yr. MLWN data was insufficient to form trend and FCP score. Mean rate therefore becomes -2.8m/yr for MHWN and MSL only. Aerials indicate retreat of saltmarsh since 1992 (c50m).


E3D1 – Ray Sand. Moderate erosion trend at MHWN (-2.5m/yr) but accretion at MSL (4.8m/yr) and at MLWN (39m/yr) giving a mean accretion rate of 13.8m/yr. MLWN extends 2.km offshore. Saltmarsh retreat by c40m in the period 1992 – 2006. E3D2 and E3D3 – Ray Sand. Moderate erosion trend at MHWN with significant accretion trend at MSL. Insufficient MLWN data for trend or FCP score. Mean trend of accretion of between 5 – 10m/yr respectively (MSL and MHWN only). Aerials show slight retreat of saltmarsh since 1992. MLWN extends 2.5 – 2.7km offshore. E3D4 – Ray Sand. Small erosion trend at MHWN (-1.2m/yr). Significant accretion trends at MSL and MLWN to give mean accretion rate of 12.3m/yr. MLWN extends up to 3km offshore. Aerials show small amount of saltmarsh retreat since 1992. E3D5 – Ray Sand. MHWN and MLWN appear highly variable. Therefore, MSL only was used (-4.7m/yr). No saltmarsh. MLWN extends between 1.5 – 3km offshore. E3D6 – Ray Sand. Good trends at all levels. No movement of MHWN. Slight accretion trend at MSL with significant accretion trend at MLWN (4.9m/yr). MLWN lies 350-450m offshore. No saltmarsh. Mean trend of accretion is 1.9m/yr. 2.3.5 Maplin Sands (Foulness Point to Havengore Head) E3C1 and E3C2 – Foulness Point. Slight erosion trend at MHWN and at MSL, MLWN shows a strong accretional trend and lies between 2.5 – 3km offshore. Saltmarsh shows little movement. Mean accretion trends are 12.3m/yr – 13.9m/yr and profiles show a flattening trend. E3C3 and E3C4 – Fisherman’s Head. These profiles show little or no movement at MHWN, with strong accretional trends at MSL and MLWN to give mean accretion values of >20m/yr. MLWN extends several kms offshore. Saltmarsh shows little overall movement. E3C5 – Eastwick Head. Little movement at MHWN. Significant accretion at MSL. MLWN does not have enough data points to give a meaningful trend or FCP score. Mean rate of accretion is 5.8m/yr (MSL and MHWN only). MLWN extends 2.5 – 3.5km offshore. Aerials show little movement of saltmarsh. E3B1 – Rugwood Head. Slight erosional trend at MHWN. Significant accretion at MSL and MLWN (although MLWN showed more variability). MLWN extends several kms offshore. Aerials show significant accretion of saltmarsh since 1992. E3B2 – Asplin’s Head. Accretion trends at all levels. MLWN shows some variability in data points but overall trend is highly accretive and extends up to 5km offshore. Mean accretion rate is 42m/yr. Saltmarsh appears relatively stable. E3B3 – New Burwood Farm. This profile shows erosion at MHWN of -0.8m/yr and significant accretion trends at MSL (12.6m/yr) and MLWN (81m/yr) which lies c3.5km offshore. Saltmarsh extent appears stable. E3B4 and E3B5 – Havengore Head. Significant accretion trends at all levels to give mean annual trends of 31m/yr and 29m/yr respectively. MLWN is 3.5km offshore. Saltmarsh extent appears stable. Flattening profile.

2.3.6 Southend-on-Sea (Haven Point to Leigh-on-Sea) E3A1 – Haven Point. No movement at MHWN with strong accretional trends at MSL and MLWNs. MLWNs extend up to 3.5 – 4km offshore. E3A2 – Shoeburyness New Ranges. Accretion trends at all levels with MLWN extending up to 4.5km offshore. Saltmarsh extent appears to have receded by c30m. E3A3 – Poynter’s Point. Small erosional trend at MHWN. Significant accretion at MSL and MLWN (extending up to 3.5km offshore). Saltmarsh may have retreated. E3A4 – Suttons. No movement at MHWN. Significant accretion trend at MSL and MLWN. MLWN extends 3.5km offshore. Rock armour in front of seawall. E3A5 – Shoeburyness. Profile shows slight erosion at MHWN and significant accretion trend at MLWN. MSL shows only slight accretional trend but has been steadily accreting since 1997. MLWN lies c3km offshore. E3A6 – Shoeburyness. MHWN shows small accretion trend with moderate erosion trend at MSL. MLWN shows high variability with a resulting slight mean accretional trend (2km offshore). No change in profile shape. Slight erosional mean trend. E4A1 – Shoebury Ness. Slight accretion trend at MHWN. Slight erosion at MSL. Significant overall accretion trend at MLWN (although data points were highly variable). Flattening profile. MLWN lies between 130 – 600m offshore. E4A2 – The Promenade, Shoebury Common. Little movement at MHWN. Slight erosion at MSL which is stronger at MLWN (-0.5m/yr). MLWN is 100m offshore. Steepening profile. E4A3 – Thorpe Esplanade. Erosion trends at all levels. Slight at MHWN and strong, -3m/yr at MLWM to give mean erosion trend of -1m/yr. Profile steeping. MLWN 600m offshore. E4A4 – Eastern Esplanade. Significant accretion trends at all levels. Mean accretion trend of 2.3m/yr. MLWN 900m offshore. No change in profile. (see Figures 15/16). E4A5 – Eastern Esplanade. Strong accretion trend at MHWN (1.8m/yr). No movement at MSL. Significant accretion trend at MLWN (10.9m/yr) to give mean trend of 4.3m/yr. MLWN lies 300 – 600m offshore although this trend is highly variable. (see Figures 15/16). E4B1 – Southend-on-Sea Pier. Accretion trends at all levels, increasing at MLWN to 3.9m/yr to form flattening profile trend. MLWN lies 600 – 700m offshore. E4B2 – Western Esplanade. No movement. MLWNs 840m offshore. (see Figure 17). E4B3 – Chalkwell Esplanade. No movement at MHWN. Significant erosion trend at MLWN of -8.4m/yr. Mean erosion trend is -2.9m/yr. MLWNs lie 600 – 800m offshore. Steepening profile. (see Figure 17). E4B4 – Chalkwell. The Leigh Swatch (offshore channel) lies 580m offshore from sea wall. Slight accretion trend at MHWN. MSL shows slight erosion trend. MLWN

shows moderate accretion trend of 0.5m/yr. Mean trend of accretion shows little movement. MSL and MLWNs lie 900 – 950m offshore respectively. E4B5 – Leigh Cliffs. Profile lines surveyed to Ray Gut (offshore channel). No movement at MHWN. Strong accretion trend at MSL. Moderate accretion trend at MLWN of 2.7m/yr. MSL and MLWNs lie 1000 – 1200m offshore (Ray Gut). Mean accretion trend is 3.2m/yr. E4B6 – Leigh-on-Sea Station. Slight erosion trend at MHWN. No movement at MSL. Moderate accretion at MLWN (0.6m/yr). No overall movement. MSL and MLWNs lie 1.5 – 1.6km offshore. Ray Gut lies at 1.6km chainage.

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Figure 16 – Southend-on-Sea. Wide beach midway between E4A4 and E4A5 looking west towards Southend Pier (2008).

Figure 17 –Westcliff-on-Sea. Much narrower beach midway between E4B2 and E4B3 looking east towards Southend Pier (2008).



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l with

sto

ne re

vetm

ent

1.79

0.

02

10.9

6 4.

26

6

E4B

1 S

outh

end-

on-S

ea

conc

rete

reve

tmen

t 0.

29

0.60

3.

85

1.58

6

E

4B2

co

ncre

te re

vetm

ent

-0.0

1 0.

24

0.04

0.

09

0

E4B

3

sea

wal

l and

gro

yne

encl

osur

e -0

.01

-0.1

8 -8

.39

-2.8

6 -1

E4B

4

pitc

hing

0.

12

-0.2

6 0.

48

0.11

1

E

4B5

pi

tchi

ng a

nd a

rmou

r -0

.01

6.92

2.

68

3.20

1

E

4B6

co

ncre

te p

aved

ear

th e

mba

nkm

ent

-0.8

9 0.

16

0.59

-0

.05

-2

Appendix 2 - References (1). SANDS software by Halcrow Group PLC. http://www.halcrow.com/sands (2). POLTIPS software by Proudman Oceanographic Laboratory. http://www.pol.ac.uk/appl/poltipsw.html Defra, 2006. ‘Shoreline Management Plan Guidance: Volume 2, Appendix E – Open coast SMP management boundaries’. http://www.defra.gov.uk/environ/fcd/policy/smp.htm Halcrow, 1988. Anglian Coastal Management Atlas. Sir William Halcrow & Partners. HR Wallingford, 1994. ‘Coastal Management: Mapping of Littoral Cells’, Report SR328 HR Wallingford , 2002. Southern North Sea Sediment Transport Study, Phase 2, Report EX4526 May, VJ, 2003. Dengie Marsh, Essex. In Coastal Geomorphology of Great Britain, Geological Conservation Review Series, No. 28, (VJ. May and JD Hanson), Joint Nature Conservation Committee, Peterborough, pp. 534-538. Mouchel, 1997. Essex Shoreline Management Plan. Environment Agency. Posford Haskoning, 2002. Essex Coast and Estuaries Coastal Habitat Management Plan (CHaMP). English Nature. Taylor, JA, Murdock, AP & Pontee, NI, 2004. A macroscale analysis of coastal steepening around the coast of England and Wales. The Geog. Journal, Vol 170, No. 3, Sept 2001, pp. 179-188.

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