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About the Study

SCOPAC Committee

Chairperson Councillor Mrs M Penfold MBE, West Dorset District Council.

Vice-Chair Councillor Jackie Branson, Havant Borough Council.

Technical assistance provided to Councillors by Mr Lyall Cairns (Southern Coastal Group Chair) and Dr Samantha Cope (SCOPAC Research Chair).

Introduction & Acknowledgements

Methods

Map Design, Symbols & Reliability

User Guide

Bibliographic Database

The STS 2012 update

The 2012 update of the SCOPAC Sediment Transport Study (STS) was funded by the Environment Agency under FDGiA, grant number LDW 41230, with additional contributions from SCOPAC.  

It is referenced as: New Forest District Council (2017). 2012 Update of Carter, D., Bray, M., & Hooke, J., 2004 SCOPAC Sediment Transport Study, www.scopac.org.uk/sts.

Sediment Transport Study 2012

HOMEBIBLIOGRAPHIC DATABASE

Pagham Estate Beach to River Adur, Shoreham-by-Sea

1. Introduction

Coastal Morphology and Evolution

This sector of shoreline has a slightly arcuate planform, with a near west to east alignment. Its continuity is interrupted by the mouths of the Rivers Arun (Photo 1), at Littlehampton and Adur, at Shoreham-by-Sea (Photo 2). The latter is an artificially maintained absolute boundary to littoral drifting of coarse sediments and is adopted as the eastern limit to this sector. The western boundary is the tidal inlet of Pagham Harbour, which is a transport discontinuity, but only a partial barrier to sediment transfer under most wave and tidal conditions. The coastal hinterland is low-lying, forming the West Sussex Coastal Plain with typical land levels being less than 10mOD for several kilometres inland. There is also a wide nearshore shelf, with the -20m seabed contour occurring between 10 and 17km seaward. The plain is backed by the Chalk upland of the South Downs that meets the coast and forms cliffs and shore platforms to the east of this unit, between Brighton and Beachy Head. The southward flowing rivers Arun and Adur, the latter reaching the coast at Shoreham, dissect the South Downs and the coastal plain. These rivers have cut deep channels into the sub-drift Chalk bedrock that have subsequently been filled with alluvium. Bellamy (1995) has described the sediment infill of the buried channel of the former seawards extension of the Arun, which was a tributary of the Northern Palaeovalley of the English Channel during the Devensian and perhaps earlier glacial periods of low sea-level.

The West Sussex Coastal Plain narrows progressively eastwards and consists of low gradient bevelled erosion surfaces resulting from successive Middle and Late Pleistocene sea-level transgressions and regressions (Hodgson, 1964; Bates, et al., 1998; Roberts, 1998; Bates, et al., 2003; Teasdale et al., 2010). Bedrock is largely concealed by a sequence of soft easily eroded mid to late Quaternary sand and gravel drift deposits. However, Eocene and Chalk basement rocks are exposed at various locations along the lower foreshore and in the offshore and nearshore zones. Relatively more resistant Eocene calcareous sandstone units create inter-tidal and offshore rock outcrops and reefs, as at Bognor Regis and between Felpham and Elmer. These result from subsequent differential sub-aerial and later marine erosion of the previously bevelled surface of the west-north-west/east-south-east striking Littlehampton anticline and Chichester-Worthing syncline, which reveals a lithologically contrasting set of offshore outcrops (Young and Lake, 1988; Castleden, 1996).

A well-defined inter-tidal beach, with a predominantly steep and often narrow gravel backshore and low gradient wide sandy foreshore, dominates much of this coastline. It is a product of inundation and erosion of the coastal plain by rising sea-levels of the Holocene transgression over the past 12,000 years. As sea-levels rose, quantities of sand and especially gravel deposited by terrestrial processes during periods of cold climate (e.g. periglacial solifluction fans) were driven landwards by overtopping to create a series of ancestral shingle barrier-type beaches located seaward of the present shoreline. It is thought that these beaches transgressed landward by continuing sea-level rise and storm activity, fed by aperiodic pulses of sediment supply from offshore sources (Cope, 2004). The present beaches are residual barrier-type features with a continuing inherent tendency to migrate landwards, though for the past one hundred and fifty years constrained by defence and protection structures. The conjectured barrier coastline was indented by several estuary re-entrants, which progressively infilled with marine, brackish and terrestrial sediments after sea-level rise stabilised at approximately 3,000 to 3,300 years Before Present. The rivers Arun and Adur once formed estuaries extending several kilometres inland, but have infilled by natural sedimentation and have also been embanked and reclaimed over the past 500 years (Wallace, 1990a; 1996). Aldingbourne Rife, Bognor Regis is another example of a former estuarine inlet whose infilling has resulted in the smooth planform of the modern coastline. The deep infill of sediment in the former estuary of the lower Arun Valley is an indication of the rapidity of mid to late Holocene sedimentation. Low bluffs, cut into both drift and substrate materials, are temporary local features of the upper backshore, usually appearing after storm action. Submerged low cliffs, ledges and reefs occur in the offshore zone, e.g. between Pagham and Bognor Regis.

A major new source of coastal data is from the Defra-funded National Network of Regional Coastal Monitoring Programmes.  The Programmes consist of topographic beach surveys, nearshore bathymetry, aerial photography, lidar, coastal hydrodynamics (waves and tides) and terrestrial habitat mapping.  Specifications for data collection are consistent for all regional programmes and the data and analysis reports are made freely available under the Open Government Licence from www.channelcoast.org.  

The Southeast Regional Coastal Monitoring Programme commenced in 2002. The Lead Authority is New Forest District Council, with data collection, analysis and reporting led by specialist teams at the Channel Coastal Observatory (CCO), Canterbury City Council and Adur and Worthing Councils. (See CCO Annual Survey Reports for further details).

Wave Climate and Tidal Regime

Most of this coastline is open to a moderate to high-energy wave climate comprising English Channel wind generated waves from the south-east, south and south-west as well as Atlantic swell waves propagating up the Channel from the west that become diffracted around the Isle of Wight. Shoreline wave exposure increases gradually eastward from Pagham to Shoreham, the sector of the Sussex coast which is least affected by the sheltering influences of Selsey Bill, the Isle of Wight and Beachy Head.

The Southeast Regional Coastal Monitoring Programme measures nearshore waves using a Datawell Directional Waverider buoy deployed at Rustington in 10mCD water depth. Between 2003 and 2012 the prevailing wave direction is from the southwest-by-south, with an average 10% significant wave height exceedance of 1.57m (CCO, 2012).

Hydraulics Research (1989), Robert West and Partners (1991) HR Wallingford (1994) and Gifford Associated Consultants (1997) and Environment Agency (2012) all report that prevailing waves are from the west-south-west and south west, with maximum significant wave heights of 5m generated over a fetch distance of 320km. For waves from the south-east, maximum fetch is 160km (figures relate to offshore of Bognor). Jelliman, et al. (1991) examined wave conditions at Littlehampton as part of a national study attempting to predict future wave climates in the context of relative sea-level rise and climate change. Using a hindcasting approach based on wind data, they determined that 40% of waves (1974-1990) came from the west or south-west, with a mean significant wave height (Hs) of 1.8m. Analysis revealed a slight increase over this period in incident waves propagating from the east and south-east, thus reducing maximum wave height values. However, for waves approaching from the south-west, Hs increased by 1.3cm per year for heights above 3.5m, and 0.5cm per year for heights between 2.1 and 3.5m. For Hs values below 2.1m there was a 0.2cm per year decrease over the time period studied. Halcrow, et al., (2001), using wind data for Shoreham observed similar trends, with a small increase in Hs values during the autumn period. Draper and Shallard (1971) analysed the wave climate at Owers Light Vessel, 11km south-east of Selsey Bill. A wave rider buoy was deployed for one year, providing 2,917 significant wave height values. A maximum of 7.6m was recorded, with Hs greater than 1.25m occurring 54% of the recording period; and Hs between 0.6 to 1.25m for 28% of this time. Maximum offshore wave height has been estimated to be as high as 15m to 20m for a 1 in 50 year frequency, but for inshore waters the equivalent value is approximately 6.90m (Hydraulics Research, 1989). Immediately offshore Pagham Harbour entrance, maximum significant waves of less than 1m height occur for 35% of the year and greater than 4.5m for 10% of an average year. The above data refer to offshore waves that have not been modified by inshore conditions of reduced water depth and complex bathymetry.

Shoreham and Middleton, east of Bognor, are locations for which wave modelling exercises were undertaken as part of the DEFRA Futurecoast Project (Halcrow, 2002). An offshore wave climate was synthesised based on 1991-2000 data from the Met Office Wave Model and then transformed inshore to prediction points at -5.3m and -5.1mOD. Potential sensitivities to likely climate change scenarios were then tested by examining the extent to which the total and net longshore energy for each scenario varied with respect to the present situation.

Although the tidal range increases from west to east, the inshore tidal current velocities decrease eastwards. Typical spring tidal range is 5.3m at Pagham increasing to 6.5m at Shoreham, with a neap range at the latter of 3.0m. Locally strong ebb and flood tidal currents are generated by the exchange of tidal waters at the Pagham, Arun and Adur inlets. At Pagham Harbour entrance, velocities range from 1.4m per second (springs) to 0.7m per second (neaps), whilst at Shoreham the corresponding speeds are 0.8m per second and 0.4m per second.  

Dominant Shoreline Processes and Management

Net beach drift and nearshore longshore transport is from west to east. Evidence of this drift direction is provided by the development of Shoreham spit over several centuries, the probable formerly eastwards deflection of the mouth of the Arun and the pattern of sediment retention in the near continuous present day groyne fields (Robinson and Williams, 1993). A sequence of transport sub-cells has been identified, using spatial variations in littoral drift rates in combination with various natural and artificial boundaries conditioning sediment movement associated with the Rivers Arun Adur inlets (Gifford Associated Consultants, 1997; Halcrow, 2006). Coastline recession has historically been rapid (e.g. Harper, 1985; Halcrow, 2006; Worthing Borough Council, 2009) though some temporary progradation may have occurred in response to landward barrier translation in earlier centuries (Smail, 1969). Since the early nineteenth century, coastline retreat has been reduced, but not entirely eliminated, by management interventions to "hold the line".

Previous to shoreline management, beaches were periodically very vulnerable to the impacts of high magnitude storm events. Examples include some 275m of shoreline retreat along the Worthing frontage in the eighteenth century, a 600m wide breach at Widewater Lagoon in 1908 and 20m of recession in less than 7 hours at Lancing in 1877. Although this type of catastrophic response has been constrained by defences since the early decades of the twentieth century, several locations have continued to experience overtopping and retreat during surge events (Halcrow Maritime, et al., 2001; Halcrow, 2006; Worthing Borough Council, 2009). Many of the original barrier beach characteristics such as a wide crest, backslope seepage cans and dissipative response to high wave energy and elevated water levels have now been lost as a consequence of intensive management (Cope, 2004).

Following increasing urbanisation of this coastline from the mid-19th Century onward the beaches have become heavily managed. The shoreline has been stabilised extensively by seawalls, revetments and groynes built on or behind the backshore gravel beach ridges over the past 100 to 150 years, such that the frontage between Selsey and Brighton is almost completely defended (Photo 3 and Photo 4). The Arun and Adur river channels have been embanked and their estuaries have been substantially reclaimed, thereby reducing their tidal prisms and flushing capacity. To maintain fixed inlets the tidal passes at Pagham, Littlehampton (River Arun) and Shoreham (River Adur) have been stabilised by breakwaters and/or training walls. Together, these hard defences and structures have had the effect of significantly reducing the net drift on the shingle upper beaches, but have only partially affected transport of sands on the lower foreshores. Over the 20th Century these defences induced downdrift shingle deficits. In addition natural sources of shingle supply reduced thus requiring increasing structural control to maintain existing lines of coastal defence (Gifford Associated Consultants, 1997; Halcrow, 2006; Environment Agency, 2008). These problems have led in more recent decades to intensive beach management involving traditional ”hard” engineering methods accompanied by replacement of timber by rock groynes, offshore breakwaters at Elmer, and more sustainable techniques such as gravel (shingle) beach recharge and updrift recycling, for example at  Goring-by-Sea, Lancing and West Beach, Littlehampton, and inlet bypassing at Shoreham. Seawalls, revetments, rock armour and bunds built on or behind backshore gravel beach ridges provide protection against all but extreme wave action (McInnes, et al., 2011). Some immediate hinterland areas are below maximum high water (e.g. Lancing and Goring-by-Sea) and have been subject to repeated flooding (twelve events at Goring-by-Sea between 1980 and 1992) resulting from the overtopping of beach crest levels during storms (Environment Agency, 2008). At Goring-by-Sea at least temporary success in reducing flood risk from has been achieved through the installation of flexible sheet piling, anchored in substrate deposits, to prevent percolation through the beach during events of elevated water levels (Worthing Borough Council, 2006).

2. Sediment Inputs

Three naturally occurring potential sources of sediment are identified for this coastline, comprising offshore to onshore transport, fluvial discharge and shore erosion. These have been supplemented in recent decades by beach replenishment and maintained by beach recycling at several sites.

2.1 Offshore to onshore sediment transport

Diffuse gravel feed by kelp-rafted shingle between Pagham Harbour Entrance and Shoreham-by-Sea

Analysis of Coastal Monitoring Programme bathymetry data and sediment sampling provide no evidence of onshore transport by kelp rafted shingle, which was postulated to potentially constitute a small (not reliably quantified) but regular and significant gravel supply in certain areas (Jolliffe and Wallace, 1973; Jolliffe, 1978). The sandy lower foreshore extends sub-tidally between 50 and 200m. West of Bognor Regis to Selsey Bill, the nearshore seabed comprises homogeneous coarse-grained sediment; no bedforms are discernible. Further seawards, between Bognor Regis and Lancing, there are considerable and extensive exposures and outcrops of rock; where there is a thin veneer of surficial sand and mixed sediments these are largely constrained by the underlying geology in localised patches and plumes. Eastwards of Lancing and extending beyond Shoreham-by-Sea, the seabed comprises of sand of a thickness to mask the underlying bedrock features. Therefore, the 2004 arrows indicating speculative weed rafted gravel transport have been removed.

Septarian nodules and reworked flint pebbles are released from nearshore outcrops of the London Clay (Aldwick Beds) between Bognor and Felpham, but this is probably a very small input into local beaches.

Wave-powered onshore shingle “creep”

Analysis of Coastal Monitoring Programme bathymetry data provide no conclusive evidence of onshore transport in the nearshore zone to support F2 arrows in the 2004 SCOPAC study. The F2 arrows were based on experiments conducted between 4km and 10km offshore from Shoreham by Crickmore et al. (1972) and Jolliffe (1978), indicated a landward drift of gravel. No evidence of the sediment reaching the shore was presented, and therefore this information does not support the process of wave powered onshore shingle ‘creep’. The F2 arrows have been removed from this 2012 update, and where suitable, replaced by O arrows to represent sediment transport occurring offshore. Refer to section 4.1 for details of O arrows

2.2 Fluvial Inputs

» FL1 · FL2

Two regionally significant rivers, the Arun and the Adur, discharge at Littlehampton and Shoreham-By-Sea respectively. Rendel Geotechnics and the University of Portsmouth (1996) have assessed the potential inputs of mostly suspended sediments from sandstones, clays derived from Eocene rocks and drift sediments, as well as flints from the Chalk, that each of these catchments provide, as follows:

FL1 River Arun (see introduction to fluvial inputs)

Quantities of fine sediment delivered at the coastline are estimated as being approximately 9-12,000 tonnes per year but actual delivery is reduced by the presence of various barriers to transport and by flow diversion at times of high discharge in the lower flood plains (Halcrow, 2004). The river is considered unable to contribute a significant gravel (bedload) input, due to the restricted source area and upstream and in-channel storage of any gravels entering the system (see Photo 1 of river mouth).

FL2 River Adur (see introduction to fluvial inputs)

Estimated potential input is 20,000 to 26,000 tonnes per year of suspended load, but actual delivery is reduced by the presence of various barriers to transport and by flow diversion at times of high discharge in the lower flood plains. The river is considered unable to contribute a significant gravel (bedload) input, due to the restricted source area and upstream and in-channel storage of any gravels entering the system (see Photo 2 of river mouth).

2.3 Coastal Erosion / Shoreline Recession

Although some lengths of the beaches of this shoreline are currently, or have until recently, been either stable or accreting, the long-term trend has been that of erosion and recession. Between the early eighteenth and mid-nineteenth centuries the unconstrained retreat rate along the Worthing frontage, for example, was a mean of 2.0m per year (Halcrow, 2006). Shoreline behaviour has been substantially modified by the insertion of defence structures over the past 100-150 years. Extensive groyne systems, in particular, have been designed to maintain or increase beach volumes. In recent decades, these structures have been supplemented or in some instances largely replaced by practices of gravel recharge and recycling. Full details of historical beach behaviour and estimated rates of retreat and advance of the position of mean high and low water are given in Gifford Associated Consultants (1997), Scott Wilson Kirkpatrick (2000b, 2000c), Halcrow (2002; 2006), Harris (2003 and Atkins (2010). Taylor et al. (2004) include a data set from this shoreline to support their conclusion that inter-tidal steepening has been a characteristic trend along much of the shoreline of south-east England since the mid-nineteenth century. In summary, the late Holocene history of this coastline would suggest an earlier stage (probably several discrete stages) of barrier beach emplacement, followed by erosion and depletion in historical times up to the introduction of formal shoreline management. Indirect evidence favouring the concept of a sequence of barrier beaches includes the apparent blockage of the former mouth of the Aldingbourne Rife sometime after the twelfth century and the presence of former barrier lagoons at Bognor, Brooklands (Worthing) and Lancing. Widewater persists as a brackish lagoon (Photo 5), but partly occupies a probable former channel of the River Adur. Wallace (1994; 1996) has noted the extensive offshore presence of a Chalk platform, patchily overlain by cemented beach cobbles offshore Felpham. He interprets the latter as the residue of one or more former barrier beaches that were submerged by an acceleration of sea-level rise after approximately 2,500 years before present. Some of the material contained in this ancestral barrier may have been incorporated into the modern beach, although it does not appear to be mobile under contemporary wave action.

Analysis of the relative movements of the positions of mean high and low water on successive Ordnance Survey maps from 1875 to 2004 reveals long-term coastline recession, intertidal narrowing and beach steepening for the majority of this coastline (Gifford, 1997; Taylor et al., 2004; Halcrow, 2006). However, since the mid to late 1960s and up to the late 1990s the general trend - but with exceptions (refer to section 5.2) - was one of overall stability or net accretion. This, however, has only been achieved through successive recharge programmes and routine recycling of beach sediment (refer to the next section); had this not been practiced, retreat rates of up to 4m per year and substantial loss of gross volume would have been experienced at most locations during recent decades (Gifford, 1997; Mouchel, 1995a and Halcrow, 2006). Two exceptions where there has been net accretion independent of management input are immediately west of Littlehampton (Photo 1) and West Beach, Shoreham-by-Sea (Photo 2). In the case of Climping, the position of mean high water advanced throughout the twentieth century and the beach gained volume due to the efficiency of the West Pier at the mouth of the Arun at trapping eastwards directed longshore transport. The same applies in the case of West Beach, although in this case there has been regular removal of sediment excess to compensate for net downdrift losses resulting from the presence of the Shoreham Harbour breakwater. Several locations have experienced fluctuating trends, notably that immediately to the east of the entrance to Pagham Harbour (Pagham Estate beach) where significant earlier recession was replaced by  accretion from the middle to the late twentieth century. Erosion and retreat have resumed along this frontage since 2002, although analysis of Coastal Monitoring Programme data up to 2012 indicates that recession rates are minimal, perhaps reflecting the influence of the installation of further defence and remedial measures. Further discussion of erosion/accretion and beach volumetric trends, and their explanation, is contained in sections 5.2 and 5.3.

Posford Duvivier and British Geological Survey (1999) have calculated that vertical wave erosion of the shoreface zone between Bognor and Rottingdean (east of this unit) yields between 1,900 and 4,000m³ per year of coarse material and 2,000 to 7,000m³ per year of fine sediment. Most of the latter is presumed to be lost to the coastal transport system as suspended load.

2.4 Beach Nourishment and Recycling

Several significant gravel beach nourishments have been completed by coastal defence authorities over the past 45 years with numerous local, small-scale beach renourishment episodes (Photo 6) that date back to the late nineteenth century at a few locations, e.g. Brooklands (Lancing) and recycling operations.

The table below provides data on approximate quantities of renourishment, by site and dates. It was compiled based on Gifford Associated Consultants (1997), Williams (2005) and Halcrow (2006), with additional information provided by Adur and Worthing Borough Council, Arun District Council and the Environment Agency.

N1, N2, N3



Beach Renourishment/Replenishments are regarded generally as having been successful, although rapid initial diminution of beach fill volume by 20-40% has been recorded at several locations. This probably results from net offshore transport of fines, abrasion of less resistant constituents and profile adjustment.

Material is lost even with well-designed and well-maintained new or reconstructed groyne systems, thus frequent “top-up” renourishments as well as routine recycling to offset losses are now common practice. Source areas for primary recharges are normally from offshore gravel deposits that are not contributing to the contemporary littoral sediment budget (Emu Environmental Ltd, 2000; Williams, 2005).

The most substantial recharge to date has taken place along the Shoreham to East Lancing beach frontage, where introduced shingle has been sourced from offshore reserves, in several phases. This has been accompanied by the construction of eleven rock groynes, designed to help retain this material (Environment Agency, 2012).

Beach Recycling

There are sites of periodic removal of accumulated beach sediments for recycling at other locations. At West Beach, Littlehampton, sediment being transported eastwards by longshore drift is retained at the West Pier breakwater. It is then removed for periodic beach recycling updrift along the Climping frontage (Elmer to Climping).

The Environment Agency conduct recycling and reprofiling of the foreshore at Climping/Atherington (Poole Place to The Mill) using a sand/shingle mix material recycled from West Beach at Littlehampton further downdrift. Records of this recycling are presented by Williams (2005) for the period 1993 and 2005. Recycling logs from the Environment Agency show this recycling has since continued, occurring twice in 2006 and then annually 2008-13. In the period 1993-2004, an average of 23,000m³ (Williams, 2005) was recycled per year. This appears consistent with the period 2006-13 with a continuing average of 23,000m³ (Environment Agency recycling logs up to 2013).

Under the Shoreham Harbour Act, Shoreham Port Authority conducts periodic harbour inlet bypassing through extraction of sediment that accumulates in the 100m length of beach adjacent to the Old Fort West breakwater (Photo 2 and Photo 7) owned by Shoreham Port Authority. This material is then deposited immediately downdrift of the east breakwater along the frontage which is not the management responsibility of the Port Authority (East Shoreham and Southwick).

Based on a calculation of net input of 10-15,000m³ per year due to eastwards longshore transport (Halcrow, 1990), an average quantity of 8,500m³ per year was removed between 1993 and 2000 (Vaughan, 2001). This increased to 12,000m³ per year between 2003 and 2011 (Worthing Borough Council, 2009; 2012). Monitoring of West Beach for the period 1993-2000 demonstrated no loss of volume and is thus regarded as a viable source for continued bypassing operations (Vaughan, 2001). 60,000m³ was transferred from West to East Beach between 2002 and 2005 (Worthing Borough Council, 2009), i.e. twice the annual quantity compared to the previous nine years. It is not clear if this indicated acceleration of the rate of loss of volume at East Beach. Excess accumulation updrift of Shoreham West Pier has also been used as a source for recharge of the frontage between Brooklands and South Lancing, although details have not been available. Between 2003 and 2011, overall accretion of West Beach, taking into account extraction for recycling, was nearly 20,000m³ (Worthing Borough Council, 2012).  

Small quantities of sediment dredged from areas of Littlehampton and Shoreham harbours adjacent to their confining breakwaters are periodically used to recharge beaches immediately downdrift (e.g. 2,000m³ was placed on Littlehampton East Beach in 2004). Williams (2005) and Moses and Williams (2008) provide further background and a critical evaluation of recent (post-mid 1970s), current and prospective recharge and recycling of the beaches of this shoreline.

3. Littoral Transport (Beach Drift)

» LT1 · LT2 · LT3   

Net longshore transport along the West Sussex coast from Pagham Harbour to Shoreham-by-Sea is eastwards, a process clearly evident from historical and contemporary observations of the eastward deflection of the mouth of the River Adur by the western spit at Shoreham (West Beach) and the consistent pattern of sediment accumulation in inter-groyne compartments throughout the frontage (Ballard, 1910; Brookfield, 1952; Smail, 1969; Robinson and Williams, 1983; Castleden, 1996 and Halcrow, 2006). Movement is substantially wave-induced, with tidal currents being insufficiently strong to move coarser sands and gravels independently, except at estuary mouths. Transport rates are spatially variable and reflect not only the energy available but also barriers to movement (i.e. the effectiveness of by-passing mechanisms) and sediment availability. However, most studies either assume or have measured highest rates over the west sector of this shoreline. This reflects, above all, incident wave approach and energy; waves become progressively more shore-parallel from west to east. Predicted or potential longshore transport rates, based on theoretical calculations, are everywhere significantly higher than actual observed or measured rates. Several authors fail to distinguish between sand and shingle and between upper and lower shore movements. Rates of transport across the lower foreshore are likely to be higher because of lack of interruption by most groynes and the finer grades of the sediments present (i.e. material with greater mobility). Smail (1969) and Robinson and Williams (1983) describe  the historical record of eastward deflection of the exit of the Adur from medieval times, so that net eastward drift would appear to have persisted at least along this sector over  the past several centuries.

Many earlier accounts are general and fragmentary and offer only limited quantitative evidence. Much more substantial are the results of several site specific numerical modelling, documentary and field-based investigations. Gifford Associated Consultants (1997) detailed the results of a numerical model (LITPACK), which calculated net sediment transport across a series of shore-normal profiles, adjusted to take account of probable groyne-induced reduction of actual transport rates. This model was operated using local data on nearshore bathymetry, grain-size parameters, sediment sorting patterns and wave climate. Changes in profile, 1972-1992, for 30 beach sections, were used to calculate annual changes between adjacent profiles, and thus deduce erosion and accretion trends that could be applied to provide validation of the modelling. The combination of LITPACK data with a conceptual model was used to derive net sediment transport volumes for a series of consecutive sections of shoreline. These are given below for each sector. It should be noted that if not specified all values in the following sections refer to potential rates, which are often well in excess of actual rates, because shortages of sediment often result in failure to achieve the predicted drift potential.  

LT1 Pagham Estate Beach to River Arun (see introduction to littoral transport)

A general west to east net drift operates along this frontage.

Rock groynes (installed in the early 1990s to replace earlier timber structures), demonstrably inhibit potential drift rates, and the local transport system is further complicated by artificial beach crest elevation, replenishment and regrading in the areas of persistent erosion (Photo 8). In 2009-2010 30,000m³ of gravel were added to Pagham Beach in response to an acceleration in erosion, sourced initially from the adjacent tidal delta and thereafter imported from an offshore aggregate extraction site.

Periodic onshore gravel migration from Pagham tidal delta and the Inner Owers is subsequently moved north-eastwards by onshore and littoral drift. A proportion by-passes Pagham Harbour inlet, involving temporary storage on the tidal delta. Thereafter, a further proportion is driven shoreward where it feeds the beach drift system that delivers material east to Aldwick. Updrift of Aldwick, an episodic history of beach retreat indicates that longshore transport is faster than onshore shingle supply (Wallace, 1990b). Between Pagham Beach Estate east of the drift divide and West Bognor Gifford Associated Consultants (1997) estimated a potential drift rate of 60,000m³ per year, which reduces eastwards to 47,000m³ per year along the main Bognor frontage, 10,000m per year of which is shingle. However, analysis of Coastal Monitoring Programme baseline topographic (2008-12), lidar and aerial photography data indicates rates of eastward drift, extending from the drift divide west of the Pagham harbour channel, in the order of 1-3,000m³ per year between Pagham and Aldwick. This is a reduction from the 2004 estimated rate of 10-20,000m³ per year, and reflects the significant accretion and storage of shingle in Church Norton spit during this period. The eastward drift then increases to 3-10,000m³ per year between Aldwick and Bognor, reaching a maximum of 5,000m³ per year at Bognor Regis. The rate reduces to 1-3,000m³ per year at Elmer, as the rock breakwaters disrupt the diminishing throughput of sediment and act as a partial littoral drift boundary. There has been little change in beach levels and volumes at Elmer from analysis of Coastal Monitoring Programme data. The sediment transport rate then increases towards Littlehampton West Pier to approximately 10-20,000m³ per year, which includes the recycling operations that occurs between Littlehampton West Beach and Poole Place (N1).

The construction of eight shore-parallel, inter-tidal detached rock breakwaters at Elmer Beach, Middleton-on-Sea (Photo 9 and Photo 10), was completed in August 1993 to promote beach accretion along a frontage with a long previous history of erosion and low drift rates. This work generated several physical and numerical modelling studies (Robert West and Partners, 1991; 1992) and a programme of monitoring. King, et al. (1996) reported that beach planform monitoring, carried out over the 32 months following scheme completion, revealed that stability was achieved after rapid initial adjustments. Individually numbered aluminium pebbles and fluorescent coated indigenous gravel sized particles were used to identify sediment transport pathways and rates of movement. Cooper, et al. (1996 a, b and c) and Cooper (1997) stated that these tracer materials moved more rapidly as breaking wave energy increased, with the coarsest particles moving furthest. The studies clearly identified a potential for sediments to drift through (along) the scheme frontage, but they could not reliably estimate typical annual volumes that might be involved. HR Wallingford (2003) gave a provisional estimation of between 3,000 and 23,000m³ per year, a wide range that presumably reflects seasonal variation in wave energy and the effects of beach salient dynamics (discussed below). It should be noted that these initial experiments were conducted on a recently renourished beach that had only undergone partial re-working and natural shaping of its configuration. It is apparent that attempts at the simulation of both cross and longshore transport need to trace all size ranges of sediment. This is due primarily to the fact that grading is initially absent on artificial beaches and subsequent morphodynamic behaviour may therefore depart from that which might be anticipated as the beach approaches a more mature, adjusted sedimentological and morphological configuration. Furthermore, Loveless and MacLeod (1999) point out, in conclusion to their research at Elmer examining the hydrodynamic and morphodynamic effects of building submerged rubble mound breakwaters, that characteristic "set-up" currents generated behind breakwaters (when water and crest levels are approximately coincident) have only partially accounted for adaptations of beach form. Illic et al. (2005) examined, from physical and numerical modelling, the influences on the hydrodynamics of wave directionality and directional spread of the detailed bathymetry and breakwater permeability at Elmer. They observed that for monochromatic normal incidence waves the highest induced current velocities occurred in the embayment behind breakwater 3; as the longshore current flows from its edge, it moves towards breakwater 4, to the east, and then turns towards breakwater 3 as it leaves the embayment, where the velocities are at a maximum. This suggests the dominance of a single current gyre in the middle of the embayment, a conclusion confirmed by experiments with other wave types. That cross-shore directed velocity moments are larger than longshore may be one explanation for marginal accretion associated with the sand tombolos between 1998 and 2001 (HR Wallingford, 2003) and some loss of cross-sectional area of the beach opposite the gap between breakwaters 3 and 4 (Atkins, 2010).

Over 220,000m³ of mixed sand and gravel was used to replenish Elmer Beach between 1989 and 1993, with the main function of the breakwaters being to retain this by reducing nearshore wave energy. The gaps between breakwaters are designed to effect a longshore transport system that minimises the downdrift impact of the shore-attached terminal rock groyne on beach volumes. King, et al. (2000) calculate, using 10 cross-shore beach profiles resurveyed monthly between April 1994 and April 1996, together with analyses of photogrammetric measurements and sediment tracing, that some 5,300m³ of material accreted on the immediate west of this frontage whilst a loss of 14,250m³ occurred to the east. The latter volume would have been greater without some interim renourishment. Well-developed shingle salients formed in the lee of each breakwater and extended seawards thereafter towards each breakwater as sand tombolos. Tracer experiments indicated gravel movement around these salients, but with no apparent net onshore to offshore losses. Monitoring of rates of sediment motion within one salient-defined inter-tidal embayment indicated a maximum drift of 57m³ per tidal cycle during a moderate storm; most of the other study intervals indicated transport of at least an order of magnitude lower than this. King, et al. (2000) thus concluded that longshore transport took place via the salients, and did not (at that time) occur in the immediate lee of the breakwaters. The presence of the latter has reduced longshore transport rates by a factor of at least two, compared to the shingle beaches immediately up and down drift. Those immediately updrift experienced some accretion following the implementation of this scheme. Compared with the original design parameters, the embayments are wider and the salients narrower than originally anticipated, thereby giving Elmer Beach a markedly sinuous beach planform. Between 2003 and 2008 the Elmer frontage recorded a modest net accretion of 3,500m³, (Worthing Borough Council, 2009) but with some fluctuation of gains and losses during this period. Between 1993 and late 1997, estimation of depletion of shingle immediately downdrift (eastwards) of this scheme (Photo 11) amounted to a potential of 22,500m³ per year (a total of 90,000m³) suggesting that efficient interception and retention by the scheme was not allowing sufficient throughput to feed the drift potential downdrift at Poole Place This shortfall, later confirmed by survey, has been partially offset since 1993 by biannual recycling of material taken from Littlehampton West Beach where it accumulates against the River Arun training works. However, between 2003 and 2008 a net erosional loss of 11,000m³ was recorded (Worthing Borough Council, 2009), most of which occurred in the sector directly downdrift from the terminal groyne .This may be explained in part by an acceleration in the local drift rate due to a change at this location in shoreline orientation with respect to the approach direction of dominant waves.

Littoral drift of gravel was calculated to be potentially between approximately 60,000m³ per year (Mouchel, 1997a, b, c) and 50,000m³ per year (Gifford Associated Consultants, 1997) at Felpham. The actual rate is likely to be significantly less, at approximately 20 to 40,000m³ per year; this estimate is proposed by HR Wallingford (2003) based on beach modelling. At West Beach, Littlehampton, Hydraulic Research (1987) using a calibrated wave power model based on a 15-year hindcast wave climate estimated net potential eastwards beach drift of coarse sand and gravel either side of the harbour mouth to be 65,000m³ per year (13,000m³ of which is gravel) to the east. The equations used in this latter study to derive sediment transport from wave power were theoretical, but the general order of magnitude is considered to be representative although an earlier study (Posford Duvivier, 1987) proposed a marginally lower volume. The LITPACK figure is similar, at just under 60,000m³ per year (Gifford Associated Consultants, 1997). Scott Wilson Kirkpatrick (2000a, b, c) derive the lower figure of 50,000m³ per year for West Beach that includes some consideration of the downdrift effects of the Elmer breakwaters and terminal groyne. It should be noted that transport uninterrupted by groynes is possible only along the 1,200m frontage of West Beach. Drift rates along the inter-tidal beach zone between Felpham and West Beach, based on monitoring data between 1995 and 2001 (HR Wallingford, 2003) were estimated to be between 21,000 (Aldingbourne) and 10,000 (West Beach) m³ per year; and for 2003 to 2007 13,000 and 24,000m³ per year respectively (Atkins, 2010). These are lower figures, in comparison to those given above, because they relate to actual rates of longshore transport determined by beach control structures. The differences between the two periods since 1995 illustrate the natural variability of drift rates over short timescales, due to inter-annual changes of wave climate, though the impact of variable year on year recycling may also be a partial explanation. Transport of gravel in the nearshore and offshore areas is given a conceptual estimate of between 30,000 and 60,000m³ per year in Atkins (2010), but the basis for this is not made explicit.

River training works and piers at the mouth of the River Arun have intercepted beach drift since the earliest constructions in 1736 and 1793 They caused accretion to the west resulting in increasing stability of what had previously been  described as a low and marshy (presumed back barrier) area subject to frequent inundations. By 1830, beach accretion to the west had produced a distinct offset in the coastal planform and sand dunes (Photo 1) began to form behind the wide foreshore. Not all drift was intercepted, for a proportion of the sand and fine gravel moved around the western training wall and thus bypassed the Arun inlet. Much of this is likely to be sand (Hydraulics Research, 1987). The progressive accretion of Littlehampton West Beach, to the immediate west of West Pier, indicates that historically there has been greater input of littoral sediment than natural losses. However, detailed study of beach profiles measured over the period 1973 to 2002 identified a trend for accretion at West Beach from 1973 to 1993, but with a tendency for erosion thereafter, especially within a zone extending 300m to the west of West Pier (Harris, 2003; HR Wallingford, 2003; Jezard, 2004). It can be postulated that less fresh sediment is entering the system due to retention by the Elmer breakwaters and that the recycling operations at West Beach are possibly removing material at a more rapid rate than it can be replaced naturally by eastward drift.

The mouth of the River Arun at Littlehampton appears to form a partial barrier to bedload movement of shingle due to strong tidal flushing and the intercepting effect of river training structures. Posford Duvivier (1987) report some overflow of fine shingle into the channel of the Arun and Hydraulics Research (1987) and Environment Assessment Services (1997) report significant sand transport across the Littlehampton Bar further offshore. Therefore, it is likely that the River Arun inlet is a more effective barrier to shingle than sand. Indeed, if bypassing of sand did not occur, recession of Littlehampton East Beach would have been significantly greater than it has been in recent decades. Jezard (2004) has analysed the historical evolution of the mouth of the Arun since the late 16th century. The first piers date back to the early 18th century and were associated with river straightening operations to improve navigation. The first reliable map to show the offset alignment of the west and east beaches dates to 1830, although there are some documentary records of West Pier extension in 1793 and 1825, possibly arising due to accretion to the west. 110m of retreat of the position of low water along East Beach (Photo 12) occurred between 1875 and 1979 (Gifford Associated Consultants, 1997), but most of this adjustment to the effects of the piers and training works upon sediment bypassing had occurred by 1900. Indeed, some advance of low water mark has occurred since 1930 (Jezard, 2004), possibly in part reflecting the periodic (but largely undocumented) addition of fine gravel and sand obtained from dredging Littlehampton Harbour and its approach channel. HR Wallingford (2003) estimated up to 20,000m³ per year of sediment may by-pass the entrance to Littlehampton Harbour, but in certain years this may be very substantially less. However, analysis of Coastal Monitoring Programme data indicates that shingle sediment by-passing across the River Arun channel harbour entrance is not occurring.

LT2 River Arun to Lancing (see introduction to littoral transport)   

Although natural potential for littoral drift on East Beach, Littlehampton was estimated to be between 20,000 and 65,000m³ per year eastward (Hydraulics Research, 1987; Posford Duvivier, 1987; Scott Wilson Kirkpatrick, 2000c), the LITPACK figure (Gifford Associated Consultants, 1997) for East Beach was an actual rate of 37,500m³ per year.

Analysis of Coastal Monitoring Programme baseline topographic (2008-12), lidar and aerial photography data indicates actual rates of eastward drift, extending from the harbour entrance channel, are in the order of less than 1,000m³ per year, due to shortage of sediment supply and interception and storage by groynes, and increase to 1-3,000m³ per year between Rustington and Brooklands. All of the shoreline between Littlehampton and Worthing is controlled by a long sequence of timber and rock groynes, revetments, and sea walls. These defences prevent free drift of shingle and control inputs to West Beach. For a distance of 1.5km westward of the western breakwater, upon the West Beach itself, transport is uninterrupted. The dominant waves from the south-west causes net drift on the beach from west to the east so that shingle accumulates against the breakwater. The sediment transport rate along this frontage increases towards Shoreham to approximately 15-20,000m³ per year, which includes the replenishment operations at Lancing (2007).

For the Worthing frontage, the LITPACK figure for eastwards movement of 38,500m³ per year was based on observed and estimated storage in the numerous inter-groyne compartments (Photo 4). This reduced slightly to 35,000m³ per year, at Lancing. Jelliman, et al. (1991) calculated changes in offshore wave climate at Littlehampton between 1974 and 1990. Based on evidence of a shift in the wave climate direction of around 6 degrees, a potential increase in actual (as opposed to potential) littoral drift rate of 1,720m³ per year was estimated to have occurred over the period 1974-1988. Holmes and Beverstock (1996) also concluded that longshore transport rates between Worthing and Shoreham vary significantly with short-term changes in wave climate. Actual rates may decline to 15,000m³ per year under low wave energy conditions (Scott Wilson Kitkpatrick, 2000c). The most significant factor that controls drift rates is the presence of groynes. Their role, for the most part, is to reduce natural throughput within the longshore transport system. The highest rates of interception and accretion take place along those sectors of coastline whose orientation is closer to being parallel to the predominant direction of wave approach - that is, near-parallel to breaking waves.

A major rock groyne and gravel replenishment scheme was completed in phases at Lancing over the period 1997 to 2003, with further subsequent additions, e.g. 117,000m³ between 2005 and 2007 (Photo 13 and Photo 14). Studies of the initial beach behaviour suggested that the new rock groynes intercepted drift and retained material effectively, but that they were partly permeable, allowing some throughput of gravel to Shoreham West Beach (Coates, et al., 1999). It should be noted that the studies were undertaken over a three month autumn season shortly following completion of one section of the scheme. Beach behaviour and groyne permeability have altered over the following years following subsequent recharges and the development of a new beach equilibrium. However, the continuing efficiency of the groyne field is apparent from modest changes in volume between 2003 and 2008 (Worthing Borough Council, 2009).

LT3 Shoreham West Beach (see introduction to littoral transport)  

West Beach comprises the western portion of a shore-parallel barrier type shingle spit fed by net west to east shingle drift that deflected the mouth of the River Adur eastwards as far as Portslade in 1810. Up to the early 19th Century there was a complex history of natural and artificial breaching to reinstate the mouth of the Adur opposite Shoreham, typically followed by renewed eastward extension of the spit (Brookfield, 1949 and 1952; Castleden, 1996; Robinson and Williams, 1983). The patterns of spit growth and river deflection therefore suggest that a net eastwards littoral transport pathway has prevailed for several centuries. The beach drift and spit behaviour has been modified since 1821 by various harbour training works designed to stabilise the inlet at approximately its present position (Gifford Associated Consultants, 1997). These structures interfered with the dominant west to east drift leading to accretion of shingle and growth of the West Beach. The present configuration of harbour breakwaters (Photo 2) dates from 1955-58 when various modifications were undertaken to improve navigation in connection with construction of the power station on the east spit (Ridehalgh, 1958). Beach evolution over the past century has been studied by Baily (2001) based on historical maps and aerial photos. The western breakwater was significantly upgraded and lengthened to around 250m, of which over 150m extended seaward of the mean low water mark on the beach. It has functioned to intercept all shingle drifting along the shoreline, although it only partly intercepts sand transport in the nearshore and offshore zones.

The Shoreham Harbour Authority have by-passed shingle (Photo 7) eastward around the harbour entrance from the West Beach to East Beach. This averaged 8,500m³ per year between 1993 and 2000 (Vaughan, 2001) increasing to 12,000m³ per year between 2003 and 2008 (Worthing Borough Council, 2009; 2012).

Analysis of Coastal Monitoring Programme baseline topographic (2008-12), lidar and aerial photography data indicates actual rates of artificial sediment by-passing at Shoreham are 12,000m³ per year on average.

As part of the Shingle Beach Transport Project (funded by MAFF and the EA) undertaken at Shoreham West Beach between 1996 and 1999 (Coates, et al., 1999), the deployment of six different tracer types over a 700m frontage indicated a net eastward actual drift of between 15,000 and 20,000m³ per year. Van Wellen, et al. (1997, 1999) and Lee, et al. (2000) reported that there was preferential transport of larger particles, suggesting the operation of sorting process that could result in beach grading. Most transport was confined to the beach face, with negligible exchange with the nearshore zone. Transport rates were closely related to wave energy flux, with "bursts" of more rapid drift. (During the experimental period 48% of waves approached between west and south, with a maximum offshore wave height of 4m). Tidal currents are weak (0.1 to 0.7m per second) and of no significance in effecting sediment transport. It was additionally concluded that vertical mixing depths have a linear relationship to significant wave height (Lee, et al., 2000). Beach elevations were found to oscillate by as much as 1m during single tidal cycles. Sediment exchange rates of 10m³ per tide for low energy waves, and 150m³ per tide for medium to high energy waves were recorded for specific experimental areas. Especially large high energy events were found to result in exchanges of up to 3,000m³/tide (Bray et al., 1996; Stapleton, et al., 1999). Taking a longer perspective, Mason, et al. (1999) found reasonable agreement for both short-term and longer time-averaged longshore transport rates, based on the application of an energetics model for shingle transport. Van Wellen, et al., (1999) however found differences between field measured (short timescale) transport and longer term accretion based evidence. Scott Wilson Kirkpatrick (2000a, c) calculate the current eastward drift to be 16,000m³ per year, with most of the gravel fraction retained by the substantial breakwater protecting Shoreham Harbour. This study concluded that West Beach accumulated 98,000m³ between 1993 and 2000. Worthing Borough Council (2012) report net accretion of just short of 20,000m³ between 2003 and 2011; during this period 101,000m³ were extracted to feed East Beach, thus gross accretion would have been close to 120,000m³.  

Beach Plan Shape Models (Halcrow, 1990; Chadwick, (1988a, b, c and d, 1989a and b, 1990; Baily, 2001; Duane 1998) have been tested at Shoreham by comparing their predictions with observed beach accretion. Models were calibrated so that littoral drift volume and direction, together with its effect on beach plan/volume, could be determined from suitable wave climate data. Despite this, wave refraction and reflection from the artificial breakwaters protecting the harbour mouth were found to cause anomalous effects on the drift pattern and beach volumes nearby, which could not be consistently predicted. Additionally, sediment transport was measured in the field using shingle traps and related to wave power to create calibrated transport equations (Bray et al., 1996). Halcrow (1990) reported that wave reflection from the breakwater caused a progressive eastwards reduction in the rate of longshore transport. This was also apparent over the frontage west to Lancing, possibly because of a slight change in shoreline orientation.

4. Sediment Outputs

» O1 · O2

4.1 Transport in the Offshore Zone

Analysis of Coastal Monitoring Programme bathymetry data and sediment sampling provide no conclusive evidence of onshore transport by kelp rafted shingle, which was postulated by Jolliffe and Wallace (1973) and Jolliffe (1978) to potentially constitute a small (not reliably quantified) but regular and significant gravel supply in certain areas. The sandy lower foreshore extends sub-tidally between 50 and 200m. West of Bognor Regis to Selsey Bill, the nearshore seabed comprises homogeneous coarse-grained sediment; no bedforms are discernible. Further seawards, between Bognor Regis and Lancing, there are considerable and extensive exposures and outcrops of rock; where there is a thin veneer of surficial sand and mixed sediments these are largely constrained by the underlying geology in localised patches and plumes. Eastwards of Lancing and extending beyond Shoreham-by-Sea, the seabed comprises of sand of a thickness to mask the underlying bedrock features. Therefore, the 2004 arrows indicating speculative weed rafted gravel transport have been removed.

O1 Sand Transport between Pagham and Worthing (see introduction to sediment outputs)

There is an apparent trend for sediment to grade from coarser to finer in both shoreward and eastward directions (Halcrow, 2004). All possess a distinctive cross-sectional asymmetry, indicating a net eastwards to north-eastwards transport pathway. Gravel waves also occur in deeper water, but are not considered to be mobile under prevailing hydrodynamic conditions. Gravel particles are considered to be stable on the seabed at water depths in excess of 12-15m.

Binnie and Partners (1987 and 1988) report that the seabed 2km to 8km offshore Worthing consists of a thin cover of sand and medium to fine gravel. Faintly defined sub-parallel ridges of very fine gravel were identified, and it was tentatively suggested that they may be the product of bedload transport by tidal currents; however, they do not clearly indicate net directions of transport. Some rock exposures related to more resistant lithologies up to 8km offshore may also be due to tidal current scour.

Potential shorewards transport of sand and gravel from the Inner Owers, 15km offshore Littlehampton is regarded as very unlikely (HR Wallingford, 1993), and this observation has provided some confidence that long-term aggregate extraction within this area should not have significant impacts at the shoreline. Environmental assessments for two proposed licenced areas (Emu Environmental, 2000) indicated possible tidal current induced sand transport pathways to the east-north-east and west-south-west. It has been suggested that dredging over the past 30 years might have had the effect of increasing nearshore concentrations of sand through entrainment of spoil materials, particularly offshore between Pagham Harbour entrance and Bognor Regis (Emu Environmental, 2000).

O2 Eastward Sand Transport off Shoreham (see introduction to sediment outputs)

A series of sand waves were mapped off Shoreham and Brighton by the British Geological Survey (1990) using information from seismic and echo sounder surveys. Sand wave morphology indicated a net eastwards sediment transport pathway. It was, however, uncertain whether these sand waves were permanent bedform features or were intermittently developed, indicating periodic transport. HR Wallingford (1993) report large areas of sand in shallower water, with dominant but thinly veneered gravel further seawards. Much of the seabed is colonised by various flora and sedentary marine life, and sediment transport potential was thus considered to be low. Gravel was presumed to be immobile below depths of 12-18m.

In both areas, residual tidal currents provide the main transport mechanism for very fine sand, although waves are a significant process in maintaining movement of suspended fine grained sediment in the nearshore zone.

Experiments conducted between 4km and 10km offshore Worthing and Shoreham by Crickmore et al. (1972) indicated a landward drift of gravel. Crickmore et al. (1972) concluded that the 9m water depth onshore feed was measured at 1,000-1,500m³ per year per km whilst at 12m depth it reduced to less than 500m³ per year per km. No transport was recorded in excess of 18m depth. The knowledge of these processes was derived from experiments with a limited quantity of radioactive tracers carried out over 2 years and correlated with wave data. HR Wallingford (1993) subsequently confirmed patchy distribution of inshore gravels together with the lack of shingle mobility beneath water depths greater than 15-18m.

Jolliffe (1978) conducted painted pebble experiments 8-9km offshore Shoreham to assess the potential for shingle transport, and observed net onshore movement. The smaller, more angular and discoidal pebbles moved the most rapidly, so any onshore input is likely to consist preferentially of these types. Transport was also found to be more rapid over areas of seafloor composed of exposed bedrock or gravel banks, (e.g. Kingston Rocks and offshore Ferring), suggesting that onshore feed might be spatially variable according to seabed roughness. No correlation of pathways of movement with tidal current vectors was apparent, and it was thus presumed that movement was entirely wave-propagated. Rate of supply was calculated to be between 750 and 1,500m³ per year per km. Few experimental details are given, so the representativeness of this estimate is difficult to assess.

4.2 Estuarine Outputs

EO1 Littlehampton Harbour Entrance and Bar

Tidal flushing operates at the mouth of the River Arun, but as training walls (Photo 1 and Photo 12) inhibit gravel entering the inlet channel (Posford Duvivier, 1987) transport mostly involves sand. Sediment sampling by Hydraulics Research (1987) demonstrated that sandy ebb tidal delta deposits extend up to 1km seaward of the East Pier comprised of sediments that drift into the inlet channel and then become flushed seaward. A study of the estuary mouth regime (Environmental Assessment Services, 1997) estimated that return shoreward transport from the delta is possible so that by-passing of sediments transported longshore occurs in both eastwards and westwards directions. The former takes place only under high wave energy conditions, as the West Pier is otherwise a major impediment. The shorter, lower level extension of East Pier (Photo 12) provides more limited impedance to littoral drift into the inlet when net westwards movement of sediment operates under waves approaching from the east or south-east. The quantity of sediment capable of moving across the harbour mouth was calculated by Posford Duvivier (1987) to be a gross volume of 5,000 to 10,000m³ per year, with a revised upwards estimate of a maximum approaching 20,000m³ per year by HR Wallingford (2003).

The mean tidal flow at Littlehampton Harbour mouth is 135m³ per second, with tidal current velocities of up to 2.5m per second. Tidal scour has thus maintained the inlet and the depth of clearance over the harbour bar, which consists of two parts, an inner component (West Pier Head to East Beacon, to about 150m seawards), and an outer component between 150m and approximately 500m seawards of the outer entrance channel. Although the inner bar is more dynamic, there has been little overall morphological change since the late nineteenth century. However, new shoals have appeared inside West Pier and on the seaward margin of the outer bar, the former tending to reform between dredging operations. A reduction of depth of clearance over the outer bar, of 0.5m between 1887 and 1993, could be due to weed growth stabilising the sandy surface of the bar, which overlies consolidated cobbles. Alternatively, this trend may indicate an increase in the volume of sediment in transit across the harbour mouth, though there are no sedimentary structures that are diagnostic of sediment mobility.

5. Sediment Stores: Beach Characteristics

Beaches comprise the main zones of littoral sediment storage. Ebb tidal deltas associated with the inlets of the rivers Arun and Adur are relatively poorly developed, possibly due to the loss of tidal prism resulting from infilling and reclamation of these estuaries. It can be postulated that larger tidal deltas could have been maintained in the past when the estuaries were larger, but their sediments would presumably have been driven onshore to feed beaches following estuary infilling and reclamation. Further information may be found at http://www.scopac.org.uk/sediment-sinks.html.

5.1 Beach Sediments

Upper beaches are composed predominantly of coarse flint gravel and are relatively steep and flat-crested and often have an upper storm berm. Lower beaches are usually composed of fine gravel, granules and medium to fine sand; they are significantly less steep forming a low gradient foreshore often extending for several hundred metres seaward to maximum low water. Overall, beach profiles are convexo-concave in form.

There are sand dunes behind Climping Beach, to the immediate west of Littlehampton Harbour West Pier that have accreted since 1830 in apparent response to the interception of drift by the River Arun training structures and the wide sandy lower foreshore that has accreted as a result (Harris, 2003). Although stabilised in parts by vegetation planting, they remain an open, active deposition system. Former dunes to the east of the River Arun, at Littlehampton, are now concealed by urban development (Jezard, 2004).

These general statements are based on analyses of beach composition at several specific locations, e.g. Shoreham (Chadwick, 1989; Coates, et al., 1999), Middleton and Felpham (Lewis and Duvivier, 1973; Mouchel, 1997a, b and c), Elmer (Cooper, 1997), Littlehampton West Beach, (Harris, 2003), Worthing (Binnie and Partners, 1987) and Lancing to Shoreham (Scott, Wilson Kirkpatrick, 1995). Quantitative data on beach sediments based on significant field sampling is provided principally by Gifford Associated Partners (1997), Cooper (1997), Coates, et al., (1999), and Scott Wilson Kirkpatrick (2000b, c) and Harris (2003). Gifford Associated Partners (1997) present trends of mean grain size, sorting and skewness separately for the upper and lower beaches. Although there are some site-specific deviations from general trends, values for all three measures display expected longshore and cross-shore responses to energy gradients created by shoaling and breaking waves.

5.2 Beach Volumes

Information includes a variety of site-specific measurements and more comprehensive sets of data for the entire frontage calculated by Gifford Associated Consultants (1997), for Climping to the River Arun, (Harris, 2003) and the shoreline between Littlehampton East Beach and Shoreham West Beach, by Scott Wilson Kirkpatrick (2000b, c) and Jezard, (2004). The studies are primarily based on data covering 1973 to 2003 derived from the Environment Agency Annual Beach Monitoring programme (refer to Riddell and Ishaq (1994) for analysis of data up to 1990). It should be noted that there are have been some uncertainties in the past relating to the reliability of parts of this data set. Changes in cross-sectional areas for the beaches between Pagham Estate Beach and Climping, 2003 to 2007 are detailed in Atkins (2010) [see below], but there are no precise calculations of volumes.

Beach thickness is available for the vicinity of Littlehampton Harbour, where 4 boreholes were drilled (Environmental Assessment Services, 1997). On the lower foreshore (East Beach), 0.2-0.3m of sand covered a 4-5m thick sandy gravel and cobble deposit overlying in situ Chalk at 10-12m. Boreholes themselves are reliable sources of information; however, it is uncertain just how representative 4 boreholes are of local conditions at the mouth of the Arun. Gravel deposits adjacent to the mouth of the Arun are probably not representative of general beach thickness because the river has excavated a deep (up to 30m) channel, which has subsequently been infilled by gravel, sand and clay (Jones, 1981; Bellamy, 1995). Scott Wilson Kirkpatrick (2000 b and c) were unable to discern any obvious trends in beach volume changes at this location for these reasons, although there may have been a small annual loss of between 1,200 and 4,700m³ between East Beach and East Preston.

The gravel volume of Pagham Estate beach, east of Pagham Harbour entrance, is estimated at 2-3 million m³ (Wallace, 1990) based upon measurement of beach width and length and an estimated thickness of 5m. No details of sediment composition changes with depth are given - the beach may have a sand, sandstone or clay base, so that gravel volume could be significantly less than the above calculation.

Scott Wilson Kirkpatrick (2000b, c) calculate a mean volume of 2.5 million m³ for central-east Worthing beach, with gains up to 1983 switching to net losses after 1988. This gives an overall annual volume addition of 7,300m³ between 1973 and 1998. Losses, mainly affecting the lower foreshore, between 2003 and 2008 were 233,400m³, taking into account the additions from recharge during this period (Worthing Borough Council, 2009.)  

The volume of West Beach at Shoreham is approximately 2.5 million m³, calculated from analyses of beach monitoring profiles derived from Environment Agency annual aerial photo surveys (Gifford Associated Partners, 1997). Scott Wilson Kirkpatrick (2000a, c) calculate that there was a steady gross increase in volume, between 1974 and 1998, in the order of 470,000m³. Duane (1998) reports an earlier net gain of 15,340m³ per year from 1971 to 1986, some 4,000m³ less than subsequently, but with some natural inter-annual fluctuation. This accretion trend continued into the twenty-first century, with a gain of 114,000m³ between 2003 and 2008 (Worthing Borough Council, 2009), not taking into account abstraction of 60,000m³ for recharge of East Beach. Some of this was derived from the renourishment of the frontage to the west in 2003/5. Longshore feed into this beach is retained by the western breakwater protecting the entrance to Shoreham Harbour, but, as stated above, an average of 8,500m³ per year was removed and placed on East Beach by recycling operations conducted by the Shoreham Port Authority between 1993 and 2000 (Vaughan, 2001). This quantity increased to 12,000m³ per year in the following eleven years (Worthing Borough Council, 2011).

5.3 Accretion/Depletion Trends, 1973 to 2008

A comprehensive review of beach volume changes between 1973 and 2000 has been provided from analysis of the Environment Agency (and predecessor organisations) Annual Beach Monitoring Survey (ABMS) by Gifford Associated Consultants (1997), Scott Wilson Kirkpatrick (2000b, c) and Jezard (2004). Harris (2003), HR Wallingford (2003; 2007),  Halcrow (2004), Worthing Borough Council (2009) and Atkins (2010) provide analysis of beach volume and cross-sectional changes between 2001 and 2008 based on more detailed and frequent measurements obtained from regional and local monitoring surveys. Analyses have sought to identify specific accretion/depletion zones and net volumetric erosion/accretion rates, an approach which is dependent on the accuracy of data sources, photogrammetric and statistical analytical techniques, imagery resolution and both the spatial and temporal representativeness of selected beach profiles. Analysis of all data sets identify trends that are apparent after inter- and intra-annual fluctuations of volumes and/or cross-sectional areas caused by short-term effects such as winter storms are omitted. Whilst these can be substantial, losses are normally followed by recovery of a high percentage of material within a few weeks. Scott Wilson Kirkpatrick (2000b, c) used ABMS data to specifically investigate trends in beach crest height and width, and beach volumes. They considered it to be reasonably reliable as an indicator of trends over decadal periods. Atkins (2010) detail reservations concerning data quality and reliability as well as the robustness of analytical procedures, but consider their observations and conclusions to be sufficient for ongoing management.    

The major trends between the early 1970s and 2011 that have been identified are (i) narrowing and steepening of most inter-tidal beach profiles along this entire frontage; (ii) beach depletion at Pagham Estate Beach (Environment Agency, 2012), Middleton, Elmer, Goring-on-Sea and Lancing, and (iii) net accretion at Aldwick Beach (24,000m³, 2003-2011), immediately west of Littlehampton and at central Worthing and Shoreham West Beach. Intervening areas have shown no consistent or uniform trends. This could mean either that (a) these beaches were relatively stable; or (b) beach volume fluctuation was such that significant trends could not be established statistically (e.g. the sector between Rustington and Goring-by-Sea showed depletion between 1983 and 1988; slow, cumulative recovery throughout the 1990s, followed during the period 2003 to 2008 by a net loss of 26,000m³, except for a 330m frontage length at Ferring (Worthing Borough Council, 2009). However, Atkins (2010) conclude that between 2003 and 2007 all of the shingle dominated beaches between the drift divide west of Aldwick and the west end of Climping showed an underlying trend of loss of volume, at a rate approximately one third of the  actual longshore drift rates detailed in section 3. A detailed analysis of erosion and accretion trends in nine contiguous sections of the beach between Pagham Harbour entrance and Aldwick for the period March 2003 to February 2011 based on volume calculations (Environment Agency, 2012) revealed dominant erosion. Net loss of volume was approximately 30,000m³ inter-annual variations of beach width and the position of the main berm crest indicated steady narrowing and retreat for the same sector. Erosion was most apparent at Middleton-on-Sea and immediately east of Aldingbourne Rife where losses tended to be focused on the lower sector of the inter-tidal profile. (There may have been a small increase in volume at Elmer between 2003 and 2008, but this would probably be accounted for by updrift recycling in excess of losses). The above observations will have been conditioned by beach management, especially the replenishment and recycling of sediments on the majority of beaches of this frontage. Their effect has been to substantially compensate for ongoing natural depletion. Modelling of beach volume changes between 2003 and 2008 revealed that any recovery was short-lived.

Analysis of profile changes between Poole Place (Photo 11) and the River Arun identified a trend for cutback erosion, crest flattening and overall loss of volume between  Poole Place and Climping and accretion at West Beach from 1973 to 1996 (Harris, 2003). Erosion continued at Poole Place thereafter up to 2002, but at significantly reduced rates. Between 2003 and 2007, erosion downdrift of Poole Place migrated eastwards, but accretion occurred to the immediate west of Climping Car Park (Atkins, 2010). At West Beach, the accretion rate reduced slightly from 1993 to 2002 with erosion being temporarily recorded within a zone extending 300m to the west of West Pier. It can be postulated that the Poole Place frontage suffered sediment shortfall for some time prior to construction of the Elmer breakwaters and that the recycling operations from West Beach since 1993 have provided compensation for this deficit. Erosion at West Beach and some marginal dune erosion at Climping between 1993 and 2003 could indicate that less fresh material has entered the system since the Elmer breakwater construction, although it could also indicate that the recycling operation may have been removing material at a more rapid rate than it can be replaced naturally by eastward drift. Between 2003 and 2008 the Elmer to West Beach sector recorded a net gain of 3,500m³ (Worthing Borough Council, 2009) suggesting that a condition of quasi-equilibrium between gains and losses had been attained during this period.

Worthing Borough Council (1987) stated that beach levels along their western frontage were previously appreciably lower. Thus, there has been a general trend for accretion of all grades of sediment throughout much of the twentieth century at a rate calculated at 7 to 9,000m³ per year. This has been attributed to the effectiveness of successive generations of groynes at intercepting drift. This assessment is based on comparisons of old photographs, plus observations of groynes periodically exposed by storms and some survey records. Reliability is only low/moderate, because insufficient quantitative evidence was presented. This report mentioned that in the mid-1980s the beach showed possible symptoms of depletion, but Binnie and Partners (1987) indicate that beach widths at Worthing are highly variable from year to year. They calculate short-term beach volume changes for this frontage of as much as 790,000m³ per year (1982-83) with apparent long-term accretion of 100,000m³ between 1974 and 1985. The equivalent calculation by Scott Wilson Kirkpatrick (2000b, c) for 1973-1998 is a net accretion gain, at approximately 9,000m³ per year, of 183,000m³. Jezard (2004) also identifies net accretion along the whole frontage from East Beach, Littlehampton to Worthing between 1993 and 2000, but her analysis of ABMS data from 1973 to 2000 revealed an overall reduction in volume. It is apparent that there has been a steady reduction of the volume of coarse sediment retained on the foreshore between Goring-by-Sea and Lancing over at least the last fifteen years, despite renourishment. This latter input amounted to 118,000m³ between 2003 and 2008 (Worthing Borough Council, 2009). Between 2003 and 2008, there was an apparent net loss of 26,000m³ of shingle within the Rustington to Goring-by-Sea beach unit, excepting for a 300m long sector at Ferring which recorded slight accretion (Worthing Borough Council, 2009). This anomaly was probably the result of recharge in 2003.  

A consequence of shoreline management by groynes has been both narrowing and steepening of beach profiles between Goring by Sea, South Lancing and West Shoreham Beach (east to King's Walk). Dobbie and Partners (1990) and Scott, Wilson Kirkpatrick (1995) identified these trends to have been uninterrupted since at least the 1870s. Mean Low Water mark retreated 1.7m per year between 1875 and 1896 and continued at a mean rate of between 2 and 3m per year up to the early 1970s. In response to very substantial losses of beach volume in the winter of 1989/90, a recharge of 110,000m³ was carried out in 1991/2. At the same time, beach crest height and width was increased. Resulting from subsequent shoreline management strategic studies (Scott, Wilson Kirkpatrick, 1995; 2000b and c), further small recharges and the construction of a series of rock groynes have been undertaken (Photo 13 and Photo 14). Recharge in 2003, 2005 and 2007  provided a total of 390,000m³ of gravel to help restore depletion of coarse sediment, thus clearly indicating that  loss of volume is an ongoing inherent problem that continues the behavioural character of the beaches of this frontage experienced during the past forty years.

Analysis of beach monitoring data by Chadwick (1989) showed that the beach immediately west of the Shoreham harbour entrance was subject to net shingle accretion (1973-82) over a stretch 1.5km long. The mean rate was estimated as being 14,539m³ per year from 1973 to 2000 (Halcrow, 2003). A total net increase in beach volume of 166,000m³ occurred over this period, with 98,000m³ accumulating between 1992 and 1995. Sir William Halcrow and Partners (1990) calculated accretion of approximately 200,000m³, 1973-1989 for the frontage extending 2,000m west of the breakwater. This figure, however, included an estimate of net deposition across the sandy lower foreshore. Analysis of beach volume trends between 2003 and 2008 indicated an increase of 75,000m³ (Worthing Borough Council, 2009) and a further 25,000m³ in the subsequent three years (Worthing Borough Council, 2011). Thus an adjusted figure for accretion 1973 to 1989 is 6,600m³ per year, but some 15 to 16,000m³ per year for the 1992-1999 and 2003-2011 periods. Some variability therefore exists in the rate of net drift operating along the beach (Halcrow, 2003). It is likely that future climate change could have moderate effects upon drift on this beach. Modelling of a range of feasible future scenarios, including sea-level rise, has indicated a possible tendency for increased rates of net eastward drift (Halcrow Maritime, 2001; Halcrow, 2002).

Baily (2001) has analysed Lancing and Shoreham beach profile data for consecutive years, and decadal periods, and has concluded that shorter-term records fail to reveal process response relations between beach morphology (including volume); transport processes and wave forcing. Antecedent beach condition was revealed as critical to beach behaviour under storm conditions. A general finding was that the upper gravel beach displayed moderate net accretion over virtually the whole coastal segment, whilst the sandy lower foreshore showed loss of volume. This would point to a tendency towards beach steepening, thus continuing a trend established over the previous 100 years. Baily (2001) has confirmed the historical pattern of steepening and narrowing, and his research reveals that recession rates, up to 6m per year, are highest around mean low water. These losses are not necessarily sustained, and may be recovered over relatively short-term periods. Symonds (2002), in a study of the short-term morphodynamics of a 100m length of Shoreham beach, highlighted changes in wave height and approach direction as the main controlling variables on profile shape, crest height  and berm migration.

6. Summary of Sediment Pathways

  1. This coastline is characterised by a dominant west to east directed littoral drift pathway operating along the gravel upper beaches and sandy lower foreshores. It forms the key central part of the wider circulation cell that operates between Selsey Bill and Beachy Head.
  2. The drift pathway has been sustained by sediment inputs from the shore between Selsey Bill and Pagham Harbour as well as receiving modest gravel inputs from the nearshore bed. Historically rapid coastal retreat has provided important sources of fresh sediment derived from this source, and erosion of the progressively submerged outcropping sand and gravel sediments and surficial sediments of the previously more extensive West Sussex Coastal Plain. Additional feed has been provided by offshore relict barrier beaches. None of these sources are now available in any significant quantity, thus partly accounting for the depletion of several of the beaches that run continuously between the much modified estuary inlets.
  3. Intensive management involving the holding of a largely fixed line of coastal defence for the past 100-150 years has eliminated natural erosion and shoreline recession and inhibited the natural tendency for landward migration of this transgressive barrier shoreline. It has greatly reduced the supply of fresh sediments and extensive groyne fields have intercepted much of the drift of gravels and coarse sand on the upper beaches. Major cross-shore training breakwaters constructed at the inlets of the Arun and Adur rivers have substantially intercepted drift, though some by-passing occurs. They function as artificial transport boundaries.
  4. Tidal exchanges at the Arun and Adur inlets exert only a modest influence upon the sediment dynamics because both estuaries are substantially infilled and reclaimed. Prior to estuary reclamation it is likely that both inlets would have generated substantial ebb tidal deltas that would have tended to dissipate wave energy in their immediate vicinity. Following the loss of tidal prism due to reclamation it is likely that most of the volume of the sediments of the tidal deltas were driven landward to contribute to the local beaches. These supplies are anticipated to be largely exhausted.
  5. Intensive beach management operations throughout this shoreline involving gravel recharge, re-cycling and bypassing supported by carefully designed and maintained control structures now largely determine sediment transport rates and volumes and attempt to maintain beach stability. Given the low-lying and erodible nature of this shoreline, its limited natural sediment supplies and the potential for sea-level rise and climate change impacts there are some uncertainties relating to the sustainability of trying to hold the present defence line in the long term.
  6. Much aggregate dredging has been undertaken in areas offshore although most studies suggest that it has mined immobile deposits and is unlikely to have had, or will have, any significant shoreline effects. Indeed, local offshore resources have frequently been used as sources for beach re-charge operations.

7. Opportunities for Calculation and Testing of Littoral Drift Volumes

Data collected by the Defra-funded National Network of Regional Coastal Monitoring Programmes is pivotal for future improvement in estimating beach change.  The Programmes consist of topographic beach surveys, nearshore bathymetry, aerial photography, lidar, coastal hydrodynamics (waves and tides) and terrestrial habitat mapping. Specifications for data collection are consistent for all regional programmes and the data and analysis reports are made freely available under the Open Government Licence from www.channelcoast.org

The Southeast Regional Coastal Monitoring Programme commenced in 2002. The Lead Authority is New Forest District Council, with data collection, analysis and reporting led by specialist teams at the Channel Coastal Observatory (CCO), Canterbury City Council and Adur and Worthing Councils. Longer term Coastal Monitoring Programme data, when combined with other data sets, academic research and historical studies may enable sediment budgets, transport rates and directions to be identified and/or validated in the future.

Estimates of gross and net littoral drift derived from numerical modelling based upon wave hindcasting are available at numerous points along the shoreline due to previous studies in support of schemes and the decision taken within the Beachy Head to Selsey Bill SMP to routinely provide such information (Gifford Associated Partners, 1997). Difficulties encountered in applying these models included the problem of selecting a representative sediment gain size on the mixed sand and gravel beaches (sediment mobility is highly sensitive to grain size) and the need to estimate (or ignore) the extent to which groynes on the upper beach intercepted any potential drift. It has meant that the data generated from these studies has had to be interpreted carefully.

Shoreham West Beach provides some of the best opportunities in the region for calculation and testing of littoral drift volumes. This is due to due to its simple morphology and bathymetry, unconfined transport and abundant shingle available for transport. These qualities were recognised by a series of researchers who have attempted to measure sediment transport in the field, develop relationships with hydrodynamic forcing and undertake numerical model application, development and verification e.g. Chadwick (1989b); Morfett (1990); Bray, et al. (1996); Duane (1998); Coates, et al. (1999); Mason, et al. (1999); Stapleton, et al. (1999); Van Welen, et al. (1999) and Lee, et al. (2000). The presence of the breakwater was especially advantageous for much of this work because the shingle accretion that it promoted to its west offered an independent estimate of long-term drift. Results from these studies suggested that extremely large quantities of sediment could be mobilised during storm events, rapid reversals of drift could occur in response to changes in wave conditions and most gravel transport was retained on the upper beach. Difficulties were encountered in comparing short and long term transport measurements and in comparing field measurements of transport with predictions made with existing theoretical approaches. Other uncertainties involved determination of grain size on the variable mixed gravel beach together with the tendency of waves to be reflected from the breakwater and interfere with transport processes on the beach.

Other comparative work has been undertaken on beaches controlled by rock breakwaters Elmer (Cooper, 1997; King, et al. 1996) and rock groynes at Lancing (Coates, et al., 1999). Although it proved possible to demonstrate that transport could occur through such schemes over short intervals it proved difficult to determine generic controlling relationships that would enable scaling up of results to longer time periods. The problems encountered related to the complex configurations of these features and the tendency for rapid initial sedimentological and morphological changes of the recently replenished beaches.

8. Knowledge Limitations and Monitoring Requirements

Notwithstanding results from the Southeast Regional Coastal Monitoring Programme, and the summarised information and assessments from the Beachy Head to Selsey Bill SMP2 (Halcrow, 2006), recommendations for future research and monitoring that might be required to inform management include:

  1. The effective application of numerical modelling studies of beach behaviour and sediment transport processes requires the input of high quality bathymetric survey data. This is especially important for those sectors of the near and offshore environments with complex landform and sediment.
  2. To understand beach profile changes it is important to have knowledge of the beach sedimentology (gain size and sorting). Sediment size and sorting can alter significantly along this frontage due to beach management, especially the practices of recharge and recycling. Ideally, a one-off field-sampling programme is required to provide baseline quantitative information along this shoreline together with a provision for a more limited periodic re-sampling to determine longer-term variability.
  3. Studies are needed of the losses of sediment that occur from beach replenishment schemes over the short to medium term and the relative roles of processes such as sorting, attrition and longshore leakage. Work could be extended to a involve review of re-cycling and bypassing schemes with consideration of processes occurring at both the "borrow" and "fill" sites.
MAP 26aPHOTOSMAP 26bLITERATURE REVIEW

Index

26a & 26b. Pagham Estate Beach to River Adur

References

Ref Map 26a / Map 26b

Rustington DWR

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​01

Start Point to Berry Head

​02

Berry Head to Hope's Nose (Tor Bay)

​03

Hope's Nose, Torquay to Holcombe

​04

Holcombe to Straight Point (including Exe Estuary)

​05

Straight Point to Otterton Ledge

​06

Otterton Ledge to Beer Head  

​07

Beer Head to Lyme Regis

​08

Lyme Regis to West Bay

​09

West Bay to Portland Bill  

10

Isle of Portland and Weymouth Bay  

11

Redcliff Point to Durlston Head (Purbeck)  

12

Durlston Head to Handfast Point

13

Handfast Point to South Haven Point (Studland Bay)  

14

Poole Harbour

15

Poole Harbour Entrance to Hengistbury Head (Poole Bay)

16

Hengistbury Head to Hurst Spit (Christchurch Bay)

Quaternary History of the Solent

​17

Hurst Spit to Calshot Spit (Western Solent Mainland)  

18

Southampton Water  

19

River Hamble to Portsmouth Harbour Entrance  

20

Portsmouth, Langstone and Chichester Harbours  

21

Portsmouth Harbour Entrance to Chichester Harbour Entrance

22

North West Isle of Wight

23

North East Isle of Wight

24a

South West Isle of Wight  

24b

South East Isle of Wight  

25

East Head to Pagham, West Sussex

26a

Pagham to Littlehampton

26b

Littlehampton to Shoreham-by-Sea  

27a

Shoreham-By-Sea to Newhaven  

27b

Newhaven to Beachy Head  

Introduction & Acknowledgements

Methods

Map Design, Symbols & Reliability

User Guide