Environment Agency update beach frontage – March 2020 Introduction

• This update has been produced to communicate information to Climping Parish Council and community instead of the meeting scheduled for 24th March 2020. This meeting was cancelled due to Coronavirus.

• This update contains the following; • Work the EA have been doing since 12th February • Comparisons between the 2015 Strategy and storm Ciara • The Environment Agency’s current position • Outline options for the frontage as requested • Resilience of the current beach Climping beach: work since 12th Feb

Working with Harbour Board and using emergency funds, we have been recycling shingle to increase the size of the shingle bank which has been constructed north of Mill Lane in an area where shingle has naturally migrated during the storms. The new bank contains extra shingle and is now more stable than the previous narrow embankment. The more landward position means waves lose more energy before reaching the beach (More detail in the section Resilience of the current beach). The bay shape allows for additional natural accumulation of shingle that, in the past would have moved straight past this location. Our recycling work has extended this bund through the Eastern Car Park field to cut off the flood route from the recently toppled concrete wall and in anticipation of further damage to the wall in future storms. Climping Beach: Work since 12th Feb Contingency and Emergency plans

In recent weeks we have met with our partners at Council, West County Council and the Emergency Services to update plans which cover the risk from a breach in the defences at Climping. The Environment Agency have robust contingency plans which include; using a bulldozer to re-profile the beach and deploying pumps to help discharge water into the as was actioned following Storm Ciara. There remains a risk that access to The Mill is difficult and may become cut off during high tides, the owner is aware of this risk and should register to the flood warning service and self-evacuate if required. We continue to monitor the condition of Climping Beach alongside weather and tidal forecasts to understand when we may see impacts. For the most up to date information on flood alerts and flood warnings, see our website ; https://flood-warning-information.service.gov.uk/warnings. To sign up to receive free Flood Warnings please call Floodline on 0345 988 1188. Climping beach: work since 12th Feb Geomorphological report and JBA update

Geomorphological Report: Following the community request to make this report available as soon as possible it was released on 12th March.

JBA consultant modelling work: Our consultants JBA have created a flood model that replicates closely the events seen over storm Ciara. Some maps are shared in the next section which explores the difference in the strategy assumptions compared with the reality of what has happened on the beach. The maps can be found on slides 10 and 11. The model will now be used to assess the future options in relation to flood risk reduction. Outcome comparison: Strategy vs Reality How long would it take?

Strategy assumptions What happened On one hand, without ‘patch & repair’ there was and expectation of a 50-50 • Deterioration of timber structures and natural transport of shingle away chance for a ‘breach’ to happen before 2020.1 from the frontage could not be delayed as might have been envisaged through the funds available. On the other hand, with ‘patch & repair’ the ‘breach’ should be delayed until • Damage to the Mill Road embankment incrementally increased from ~2030 to 2050. 2 2006, but especially since Storm Imogen (4/5 January 2018) •  wave and water level conditions needed to be less severe for it to fail than for an ‘undamaged’ structure as anticipated in the strategy Outcome comparison: Strategy vs Reality Resistance of beach and embankment Strategy assumptions What happened The overtopping calculations assumed 3 • The storms have exposed the clay slope (A) under the beach that was • a shingle beach with the associated roughness that reduce the run-up much closer to the beach surface than assumed. Wave run-up over a of the waves clay slope reaches higher than on a deep shingle beach. • an overtopping rate that leads to damage at the rear of the • The historic bank turned out to mainly consist of a shingle ridge faced embankment (which is based on clay dikes covered with turf (e.g. in with a single layer of block work and relatively thin layer of clay on the the Netherlands or in Germany) top and the rear slope (B). Overtopping water running down the rear slope quickly stripped vegetation and clay and then washed out/eroded the bank from the back

A) 10-02-2020 B) 12-3-2020 Outcome comparison: Strategy vs Reality Breach dimensions and storm duration Strategy assumptions What happened The Strategy assumed • The gap width increased gradually and exceeded the 15 m measure • a ‘catastrophic failure’ to be a >15 m wide opening 4 already in 2016 • Storms would only last over one high tide with beach recovery after the • From 2018 onwards gaps were patched with shingle in bags which storm were more resistant than just loose shingle but were outflanked on every storm a little bit more either side

• Storm Imogen in January 2018 lasted over 4 high tides • Storm Ciara in February 2020 lasted over 4 high tides

Cumulative gap width/widths at Mill Road over time Outcome comparison: Strategy vs Reality ‘Breach’ size

Strategy assumptions What happened • A broad range for the variables going into a model is acknowledged • Many of the assumptions that went into a model have turned out to be different from reality (see preceding slides) • The size of a ‘breach’ is limited by the existing topography 5 • The size of the opening was limited by the topography and the coastal processes, ie the sill level was higher than that used in the model • The selection of a representative opening is a key area of uncertainty 6 • The range of openings investigated in the strategy covered the opening observed during Ciara and the ‘centrally representative values’ covered the first high tide of storm Ciara (see preceding slide) which had a width of ~80 m but a sill level of only 3.5 to 3.9 mOD. However, with three more high tides to follow the damage length increased and the sill level dropped in placed to the level of 3 mOD Outcome comparison: Strategy vs Reality Inundation extent

The background shows a satellite image of the area on 11-02-2020 at 11:16 (just before over washing at high tide started on the 2nd day of Storm Ciara). Apart from the field north of the A259, the flooded area is within the extent under a 1 in 50 year breach event southwest of Ferry Road and within the 1 in 200 year breach event in the remainder.

Previous modelling did not account for the large culvert under the A259. Purple is the area under >~0.2m of water, bright green is dry land and vegetation, white are clouds; transitions to lighter purple and purple/green is water <~0.2m deep Outcome comparison: Strategy vs Reality New modelling

The consultancy company JBA have created a new model calibrated with all available observations over the four days of Storm Ciara which shows a very good agreement between the area flooded in the satellite image and the modelled extent. This can be seen in the map.

The model will be used to assess the risk and protection potential of options.

Purple is the area under >~0.2m of water, bright green is dry land and vegetation, white are clouds; transitions to lighter purple and purple/green is water <~0.2m deep Climping beach: EA’s current position

• Our shingle reprofiling and recycling works are complete and operational activity has now stopped on the beach. • We will be doing public safety works shortly and in the future to remove the wooden groynes and structures which have been exposed by recent storm surges and are posing a hazard. Please be careful to avoid these structures when visiting the beach. • Approximate spend: 2018/19 Maintenance : £22k 2019/20 Maintenance : £60k 2019/20 Emergency funding : £50k • The Arun to strategy has a 'do minimum' (patch and repair) approach to this frontage. It is clear that we are reaching the end of this stage as the beach structures can no longer be repaired. At this stage, the strategy recommends that we cease maintaining the frontage. We are currently reviewing our position with respect to this and we welcome your feedback to help inform our decisions around what should happen next. At the same time, we are doing what we can, within the limited funding available, to make the beach as resilient as possible. Climping beach: Outline options for the community

The Environment Agency work within certain guidelines, which shape what we can do and the money available for us to do it. Our Arun to Pagham Strategy sets the direction for our activities on the Climping frontage.

The community have requested options on what others are available and these are presented in this document. These options fall outside our parameters and would prove a challenge for us to justify and fund.

Arun to Pagham Strategy - Economic The strategy recommended do minimum approach for the Climping beach ‘non-legal’ section. This is a reactive patch and repair approach to maintenance of the beach and structures, whilst acknowledging that at some point in the future the costs of maintaining the beach will exceed what we can justify spending under government rules, at that point our maintenance activities will cease.

Shoreline Management Plan - Environmental The recommended long-term plan for Littlehampton Harbour to Poole Place is to allow the coastline to realign to a more naturally functioning system, whilst continuing to provide flood defence to the large hinterland floodplain. Climping beach: Outline options for the community

Option Cost (£m) Life span Pros Cons Timber groynes 1.2 to 1.5 30 to 40 Similar to current Requires maintenance and years replacement

Rock groynes 2.1 100 years Long life span, low Visual impact, construction maintenance needs impact Alternative material 2.5 to 6.6 < 40 to 75 Safe to construct, Deterioration, high carbon groynes (steel/concrete) years good life span footprint, inflexible. Fishtail groynes 6.5 100 years Holds beach position, Visual impact, construction low maintenance impact, down drift sediment starvation Rock islands (like 5.0 100 years Continuous beach Visual impact, construction Elmer) access, long life span, impact, design uncertainty low maintenance Concrete or steel wall 7.2 to 10.0 < 40 to 100 High certainty of No beach, difficult access, years Standard of Protection requires additional protection and end structures Climping beach: Outline options for the community

Option Cost (£m) Life span Pros Cons Containers* 0.325 for 200m 1 to 2 years Relatively quick to Temporary only, uncertain 0.560 for 500m (10 to 20 if install performance, visual and permanent) environmental impacts Rock revetment 12.0 100 years Independent of a No beach, visual impact, beach, most difficult access, ‘guaranteed’ SoP construction impact Swash aligned bays 5.0 to 10.0 100 years Naturally May require beach functioning, can management, loss of land evolve and property Shingle beach (rolled back) 0.4 to 2.4 100 years Already largely in Move landward, loss of place, natural land and property process, adaptable • Option descriptions, structure positions and costs are at very high level but provide a way to compare and rank the cost of the different options • Pro and Con lists are non-exhaustive, non-hierachical and include subjective judgement • All options would be subject to landowner agreement, permissions and consents • Options are primarily ‘capital’ schemes, that is new structures would have to be built and depending on structure may require maintenance. • Almost all options run against the SMP principle “to allow the coastline to realign to a more naturally functioning system”, excluding the Swash aligned bays and Shingle beach options • * This was requested by Climping Parish Council as a short term response to Storm Ciara and would not address the long term risk along the frontage. Climping beach: Outline options for the community

Timber Rock Fishtail Island Wall* Revetment Beach Swash aligned Groyne Groyne Groyne Bay

Structures across the beach Structures along the beach

* A more detailed evaluation of the use of shipping containers Options not to scale on the beach has been provided as a separate document. Structures across the beach

Structures across the beach, ie groynes are used to (in ascending order of impact to beaches down drift, e.g. the SSSI) • Slow down the rate at which beach material moves from west to east and thus • Trap sediment and grow the beach or • Divide the beach into compartments that are filled with beach material with little or no sediment movement between these bays thereafter.

They can be made of timber, rock, concrete steel, or recycled plastic*.

They can simple lines or more complex forms like T- Head, L-Head or fishtail.

Nearshore rock islands have a similar impact on the beach but are covered under “structures along the beach”. * largely halted due to the issue of releasing plastic into the marine environment Climping beach: Outline options: Timber groynes • Timber groynes costs about £110k to £135k each (60 m long, 60 m apart) , i.e. 11 new groynes  £1.2 to £1.5 million. • Costs depend on how the piles can be installed (driving or pre-drilled) which depends on the ground conditions, the length of groynes and the size of the beach to ensure they are not outflanked. • A beach or a hard structure may be required at the landward end of groynes and the bays may need to be filled with shingle (additional costs) • The beach in the groyne bays has to be maintained to a certain volume and position, otherwise the groyne becomes ineffective (landward outflanking) or the wave load may Con damage the groyne. • Plan shape position uncertain to establish Pro • Risk of outflanking at eastern end / impact on SSSI • Looks similar to now/in the past • Maintenance required when planks deteriorate • Proven construction method • Will need replacement after 30-40 years • At replacement intervals (30-40 years) there is an • Reliance on beach material coming from the west or opportunity to relocate groynes and beach landwards recycling if the beach size reduces Climping beach: Outline options: Rock groynes

• Similar to beach • Rock groynes are ~£350k each and 6 would be required (one rock groyne for every 2 timber groynes)  ~£2.1 million • Costs depend on the amount of excavation required, the length of groynes and the size of the beach to ensure they are not outflanked • A beach or a hard structure may be required at the landward end of groynes and the bays may need to be filled with shingle (additional costs) • The beach in the groyne bays has to be maintained to a certain volume and position, otherwise the groyne becomes ineffective (landward outflanking) Con Pro • Plan shape position uncertain to establish • Proven construction method • More significant visual impact and safety concerns for beach users • Rock can be re-arranged • Bigger construction impact (such as Elmer) • Last longer than timber groynes • Risk of outflanking at eastern end / impact on SSSI • Low maintenance needs • Reliance on beach material coming from the west or recycling if the beach size reduces Climping beach: Outline options: Steel/concrete groynes Concrete groynes: (6no. 60m long ~£7k/m) Steel groynes: (11no. 60m long ~£10k/m)

Pro Pro • Narrower than rock groynes • Easy to install • Less of the H&S concern than rock • No excavation required

Con Con • Excavation required • Excavation required • Question of stability on the existing ground • Question of stability on the existing ground • Durable but less flexible to change in future • Durable but less flexible to change in future years years • Large carbon footprint Climping beach: Outline options: Fishtail groynes

• A Fishtail groyne essentially combines a nearshore rock island with a groyne by connecting the island to the backshore • Based on Clacton-on-Sea one groyne +40,000 m3 of recharge recharge was £1.3 million, five groynes  £6.5 million

(Groyne foot print and position of shoreline simply transposed from Clacton-on-Sea.)

Pro • Con • Holds the beach in position • Not very sightly at low tide (mostly covered at high tide) • Does not rely on continued feed of • Bigger structure than the breakwater/island (more visual impact and beach from the west. higher costs) • High impact on SSSI through starvation of sediment • More variables in the design and will require extensive modelling Structures along the beach

Structures along the beach - either seaward of landward of a beach - are used to • Reduce the wave energy that reaches the beach • Modify the alignment of the wave crest reaching the beach • Provide a hard barrier between sea and land

They can be made of rock, concrete or Top right is Elmer showing how wave crests are refracted into a semi circle shape and how wave energy is steel. much less in the left hand bay than in the right hand (as a function of the gap between the rock islands)

Rock revetment fronting a concrete seawall and promenade protecting low lying land at Broomhill Sands, Kent Climping beach: Outline options: Rock Islands

• Breakwater foot print and position of shoreline simply transposed from Elmer. These are about 140m long (western long ones at Elmer) • One Island is ~£1.2 million, four islands  ~£5 million • Beach behind will have to be filled with beach material (additional cost)

Pro • Continued access along the beach without obstacles • Rock can be moved/rearranged • Will last a long time • H&S risk of the rock structure is • Con more removed from potential • Not very sightly at low tide (mostly covered at high tide) ‘users’ • Dimensions and positioning will require significant modelling and design (additional cost) • Relies on continued beach feed from the west Climping beach: Outline options: Sheet Pile Wall

• £10k per metre. The line is 1000 metres long ~£10 million • Cost depends on length of piles (assumption for 15m long piles, top of pile at 5mOD) • Concrete wall ~£7.2k/m, £7.2m.

Pro • Independent of a beach • Provides a ‘guaranteed’ standard of protection

Con • No beach • Not very sightly when exposed • Difficult access across • Would need additional embankment and promenade behind? (additional structures like steps • Will only last a few decades unless protected at the seaward side by rock requiring maintenance) • Uncertain development at either end may require future works • High carbon footprint • Wave reflection will increase seaward erosion and possible further east Climping beach: Outline options: Containers • £0.3 million for 17 parallel to the Mill Road • £0.56 million for 42 to also include the lower lying car park • £0.8 million for 60 to cover the entire length as illustrated • A more detailed evaluation of the use of shipping containers on the beach has been provided as a separate document

Pro • Installed relatively quickly Con • No beach • Not very sightly when exposed • Difficult access across (additional structures like steps) • Would need additional embankment and promenade behind? • High carbon footprint • Will only last a few decades unless protected at the seaward side by rock • Position on top of the beach and • Unlikely to be permitted as permanent feature in single units make them likely to • Uncertain development at either end may require future works move • Wave reflection will increase seaward erosion and possible further east Climping beach: Outline options: Rock revetment

• 150m all in all is £1.8 million, the line is 1000 metres long ~£12 million.

Pro • Independent of a beach • Works on its own • Provides the most ‘guaranteed’ standard of protection

Con • No beach • Not very sightly when exposed • Bigger safety risk for people climbing across to access • Difficult access across • Would need additional embankment and promenade behind (additional structures like steps • Massive construction impact requiring maintenance) • Uncertain evolution of the coast at either end may require future works. Climping beach: Outline options: Swash aligned bays (SMP option)

• Expanding the principle employed at Elmer to a larger scale • Built of rock and requiring large modelling and design effort the very rough estimate would be  in the order of £5m to £10 million • Options include adding a third island between Climping and the River Arun (additional cost) or modify the positions of the two shown. • Only the rock islands built and the coastal alignment with Pro Con evolved through • Largely naturally functioning coast • Additional beach management may be necessary natural processes • Works on its own • Loss of land and eventually properties over decades. • Allow the coastline to evolve • Requires changing access arrangements Climping beach: Outline options: Beach (rolling back) (SMP option) • A 1000 metres long beach, on top of the existing terrain with an average 60m2 cross section (e.g. smaller on the higher car park and larger behind Mill Road) requires 60,000m3 of shingle. A significant volume of this is already in the beach placed in the • Depending on the source landward position following storm Ciara (white area); the 3 this costs between £40/m frontage is east of Bread Lane is already covered with a beach for offshore supply to of those dimensions! £6/m3 for recycling from More will be brought in over time by natural feed from the west. Littlehampton  between £0.4 and £2.4 million Pro Con • Is already largely in place • Will increase the SSSI • The beach will move landwards • Works with natural processes • Can be increased in size • Loss of land and eventually properties at • Natural beach without structures length over time in Climping Street • Can change and adapt to sea level response to requirements rise (within limits) • Requires changing access arrangements Resilience of the current beach

A shingle beach is a very effective natural defence as is visible just east of Climping and along much of the Sussex coastline. Beaches absorb wave energy, for example, through the friction they create for the waves and in the way they change their shape depending on the wave conditions. Hard structures like vertical walls work by blocking the wave energy and reflecting it out to sea again which leads to erosion right in front of them as can be seen in front of the car park wall. It also means that the structure will eventually be broken down through the wave impact. However, for a beach to be sustainable into the future it needs the space to change its shape (in a storm the beach slope becomes longer and shallower) and adjusts to rising sea level by moving landward. What will happen in the next storm/spring tide? Re-establishing the beach! The map on the right shows the location of the profile line towards the western part of the overwashing gap created by storm Ciara crossing the newly created shingle bank landwards of Mill Road.

The graph shows elevation along the profile line (red line above) for five surveys from 15-12-2014 to 12 -03- 2020. It shows the narrowing of the beach up to the pre-Ciara situation represented by the survey on 19-11-2019 and the

Mill Road location Road Mill progress of re-establishment. The profiles are almost identical seawards of ~80 m but the beach crest is ~20(35) m further landward than in 2019(2014) providing a shallower slope over which more wave energy is lost. Strategy references (slides 6-9)

1. “At present, the shingle ridge on the Climping frontage has a typical 50% probability of breach occurring within the next five years (following completion of the minor works to reinforce the frontage against mach-stem wave attack in June 2014), assuming no further maintenance is carried out.” Appendix P:5

2. “The annual benefit of the Do Minimum option at Climping was compared against the annual costs. For the chosen mid-range 3.3mOD sill level analysis, benefits are greater than the costs until Year 31. Therefore, based on this economic analysis and the best available data, it is likely to be economically viable to continue to Do Minimum and undertake regular repairs to the Climping frontage until Year 31, unless a major breach occurs before that time. Minor breach damage variability indicates that this duration should be expected to vary with a range of 14 to 34 years” Appendix P:65

3. “The resilience of the defence was determined by comparing these likelihoods to critical overtopping threshold values. These threshold values represent the overtopping rates at which the defence is likely to experience damage or breach.” Appendix P:13

4. “In its relatively recent history (1970’s onwards), there are no known catastrophic failures of the defences leading to large (>15m wide) openings in the shingle ridge. Localised overtopping and in some cases damage through under wash is common (one to two times per year in recent years). Such damage is limited in extent with beach berms forming in the shingle as the storm subsides or over the ensuing period.” Appendix P:31

5. “Breach conditions: Once overtopping rates exceed the breach threshold rate, it is assumed that an opening will develop in the shingle ridge. The width and sill level of this breach will vary significantly depending on the structural state of the shingle ridge and foreshore, the size and duration of storm conditions and the prevailing sea conditions immediately following the storm. The range of this variation is broad, but ultimately constrained by the topography of the area, notably the length of the narrow section of shingle ridge, the rear berm to the ridge formed by an access road and the ground levels behind this road. In order to determine the volume of water entering the flood cell through the breach, a representative opening has to be selected. This is a key area of uncertainty in the analysis, so a range of values for breach width and breach sill level have been tested to identify the stability of the option selection against these parameters.” Appendix P:8

6. “centrally representative values: […] Width of ensuing breach = 80m, Sill level of ensuing breach = 3.3m.” Appendix P: 37