MEDWAY ESTUARY AND SWALE FLOOD ANDEROSION RISK MANAGEMENT STRATEGY
CONSULTATION DOCUMENT – WINTER 2017
Milton Creek in Sittingbourne (BA 5.2) Kingsnorth Power Station (BA 1.2) Promenade and Groynes at Minster (BA 11.1)
Wouldham Marshes (BA 3.5) Leysdown Beach (BA 9.1) Oare Creek (BA 6.1)
Introduction
Aim of the Document:
We are keen to hear your views and inthis document we:• explain what the Medway Estuary and
Swale Strategy (MEASS) is• explain the key risks including the
current level of flood and erosion riskand the effects of climate change;make recommendations for managingthese risks
• look at the next steps for the Strategy• provide links to further information and
ways to comment.
This non-technical summary documentoutlines the work undertaken to date forMEASS and the potentialrecommendations to manage flood andcoastal erosion risks within the Strategyarea. A glossary of terms and acronymscan be found at the end of this document.
We cannot eliminate these risks, but wecan reduce their impact by working withothers and preparing for them. MEASS isbeing developed by the EnvironmentAgency in partnership with otherorganisations which share coastalinterests in the area. These includeNatural England and the Local Councils.Participation in the development ofMEASS is not limited to theseorganisations and contributions have andwill continue to be welcomed from anyorganisation or individual with an interest.This approach is being taken to ensurethat MEASS is widely understood andjointly supported.
MEASS has reviewed the policies thatare set out in the 2010 Medway andSwale Shoreline Management Plan(SMP) and the 2010 Isle of Grain andSouth Foreland Shoreline ManagementPlan (SMP) (http://www.se-coastalgroup.org.uk/category/shoreline-management-plans/). These plans conclude that acombination of Hold the Line, andManaged Realignment options should beimplemented to help protect thecommunity from coastal flooding anderosion over the next 100 years.
In particular, they both make reference tothe important environmental designationsin the area and the impact of sea levelrise on coastal squeeze. MEASS isneeded to enable these policies to bereviewed, developed and updated whereappropriate, and then delivered.
MEASS will aim to be a sustainablecoastal flood risk strategy which willshape the area for the next 100 years.We cannot be certain about futurechanges and so it will be recommendedthat MEASS is reviewed in the future asmore information becomes available. Thisis particularly true when assessing thepotential impacts of sea level rise and theeffects on the hydrology and sedimentmovement around the estuary. Numericalmodelling has been used in MEASS tolook at potential future scenarios andimpacts.
Figure1: Saltmarsh areas along the south of the Isle of SheppeyPage 1
Strategy AreaThe MEASS area encompasses the Isle of Sheppey, Medway Estuary and the Swale.The Medway Estuary and Swale includes the large urban areas of the Medway Townsincluding Rochester, Strood, Chatham and Gillingham. Within the MEASS area thereare:• a number of major industrial and commercial areas• important infrastructure including the railway lines, electricity lines and roads• large swathes of rural farmland• extensive salt marsh and mudflats along the Medway and Swale Estuaries and the
Isle of Sheppey.
Many of the rural areas are environmentally designated and protected for theirheritage, landscape, and environmental value. There are also large areas ofagricultural land which are important to the economy.
As the MEASS study area covers approximately 120km the coastline has beenbroken down into a series of Benefit Areas (BAs) based on discrete flood cells andland use. These BAs have been broken down further into 35 sub-BAs based on theSMP policy units. Figure 2 demonstrates the different BAs.
Although there are key risks and vulnerabilities that apply throughout the MEASSarea, each BA has it’s own specific requirements from coastal management and thisassessment has taken these into account.
Figure2: Map of the MEASS area divided into BAs. Page 2
Flood Risk andClimate Change
Flood risk combines the probability of aflood occurring and the impact the floodwould have.Flood risk assessed within MEASSconsiders flooding from the sea only(including the tidal reaches of theMedway Estuary).In assessing flood risk it is important toconsider the impact it may have onhomes, infrastructure, businesses andthe environment.
Climate ChangeWe expect sea level to continue torise at increasing rates with climatechange. Our best estimate currently isthat the sea will rise by approximately0.8m over the next 100 years in theMEASS area. This increase can havea significant effect on overtopping ofsea defences and coastal flood riskwithin an area.
Increasing Risks for PeopleHigher sea levels lead to greater risksof flooding, particularly in stormyconditions. Coastal flooding that hasonly a 1% annual chance of occurringtoday will potentially have a 10%chance by 2067.
Climate ChangeThe climate is changing and we expectsea level to continue to rise atincreasing rates. As the sea level rises,the wave energies which impact theland will increase and the rate oferosion of the land will also increase.This can have a significant impact onthe area of land at risk from erosion.
Increasing Risks for PeopleIf defences are not maintained, the landbehind these becomes vulnerable toerosion. The soft nature of the cliffsmay see rapid erosion issues similar tothe soft cliffs of Norfolk and Suffolk.Rising sea levels increases this risk oferosion.
Erosion Risk andClimate ChangeErosion risk occurs from the ongoingerosion of the land by wave action,combined by the impact of the loss ofland.There are some areas in MEASS wheredefences are present to protect againsterosion, but there are others where thecoastline should remain undefended,due to the environmental designationsbeing based on the geology of the cliffs.
Figure 3: UK climate change projections over the next 100 yearsPage 3
Managing Impacts on the EnvironmentProtected AreasThere are a number of national and international environmental designations in theMEASS area. These designations have to be adhered to when developing the optionsto ensure that the negative impacts on the designations are mitigated.
Coastal SqueezeIntertidal areas such as saltmarsh and mudflats, which can be seen at low tide, will beunderwater for longer in the future due to rising sea levels. Built defences, such as seawalls and beaches, can cause a reduction in the area of mudflats and saltmarsh as thesea level rises. This is because the habitats are prevented from moving further up theshore by the presence of the defence. This process is called coastal squeeze.
Coastal Squeeze will affect the wildlife that depend on these habitats, including thebirds, which are of international importance. We cannot stop sea level rise but we cantry and compensate for the loss of habitat caused by our built flood defences, bycreating new areas of suitable habitat.
Future management of the coastline will need to protect the natural environment andbe cost-effective. This may mean that in certain areas formal defences may need to bewithdrawn in the future to let more natural evolution of the habitats.
An assessment of the potential coastal squeeze of intertidal mudflat and saltmarshhabitat, as well as impacts to freshwater habitat from not defending the coastline or notraising defences in line with sea level rise. We have worked very closely with NaturalEngland, RSPB and Kent Wildlife Trust to ensure that the least damaging schemes areproposed.
Within MEASS, a study has been done which estimates a total loss of saltmarsh overthe next 100 years of 113ha (0-20 years), 140ha (21-50 years), and 308ha (51-100years). The Strategy looks to address this by creating Managed Realignment Siteswhich will aim to provide areas to create additional intertidal habitat.
Environmental ReportsMEASS will be supported by anenvironmental study which will look at thepotential impacts of the Strategy on theenvironment and identify required mitigationgoing forward to reduce impacts. This ispresented as the Strategic EnvironmentAssessment (SEA) Report. This Report willbe supported by a Water FrameworkDirective Assessment, as well as a HabitatRegulations Assessment to comply with theinternational legislation.
CoastalSqueeze
Natural Habitat Migration
Figure 4: Diagram illustrating coastal squeezePage 4
MEASS will guide the approach taken to manage coastal flood and erosion risk aroundthe Medway and Swale estuary over the next 100 years.To define the management approaches, government guidance and processes must befollowed and presented within the Strategy.As this is a Strategy stage document, the aim here is to identify management
Task 1: Define Long List of OptionsTo develop the management approach,we have first considered a range ofpotential options for each Benefit Area .This was developed in consultation with anumber of stakeholders. The optionsconsidered included:
Hold the Line (HTL) – continuedmaintenance, repair and building of newdefences to stop coastal erosion of thecoastline and protect (to a definedstandard of protection) from coastalflooding.
How Flood and Coastal Erosion RisksCan Be Managed
Managed Realignment (MR) – creationof a new line of defence either seaward(advance the line) or landwards(retreat).
No Active Intervention (NAI) – noactivity or works to maintain, repair orbuild defences.
Adaptation Measures – improving theflood resilience and resistance at anindividual property level.
Task 4: Select the Leading OptionThe results from Task 3 present leadingoptions which are then tested throughnumerical modelling, environmentalreporting and stakeholder engagement,of which this document is an importantpart.
Task 2: Screen Long List to CreateShort List of OptionsThe long list of options for each BenefitArea was assessed against technical,environmental, social and costfeasibility.
Three different Hold the Line optionshave been considered: maintain,sustain and upgrade (Figure 7). Thesedifferent options provide differentimprovements to the standard ofprotection from coastal flooding.
Task 3: Evaluate the Short ListTask 3 refers to the work that wasundertaken to evaluate the short list ofoptions in detail, looking at theeconomic viability, environmental andsocial acceptability, and differentsensitivity options in more detail.
Task 5: Select the Preferred Optionsand submit for approval.Following Task 4, updates will be madeto the Leading Options which arepresented in this document, and thefinal Strategy will be written andsubmitted for approval to DEFRA.
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How Flood and Coastal Erosion RisksCan Be Managed (continued)
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Managed Realignment (MR)MR is a multi-functional, multi-benefit approach to managing coastal flood risk.
The key benefits of MR are:• Moves the defence line inland, which reduces the long term costs of maintaining
flood defences and can relieve pressure on neighbouring flood defences.• Sustainable approach to managing flood risk.• Naturally adapts to climate change and sea level rise.• Creates valuable intertidal habitat.
No Active Intervention (NAI)NAI involves the Operating Authority (Environment Agency/ Local Authority)reducing, and eventually ceasing all work on the defences including patch and repairmaintenance. As such the defences could fail and there may be inundation/erosion.
JustificationIn these areas the costs of maintaining the defences outweigh the economicbenefits associated with the reduced risk and government funding can not bejustified to realign or replace the defences, so nature is likely to take its course. Thisis not likely to occur immediately in a lot of areas. The EA will aim to advise ownersas there might be the option for private investment in the defences subject tolicencing and approval.
Undertaking Private worksUnder the Environmental Permitting (England and Wales) Regulations 2016, youmust submit plans to the Environment Agency and apply for a Flood Risk ActivityPermit (FRAP) if you wish to undertake works:• In, over or under a main river.• Within 8m of the bank of a main river, or 16m if it’s a tidal main river.• Within 8m of any flood defence structure or culvert on a main river, or 16m on a
tidal main river.• Within 16m of a sea defence operated by the Environment Agency.• In a flood plain.
Figure 5 and 6:L: River Medway atHallingR: Marshes on the southof the Isle of Sheppey
How Flood and Coastal Erosion Risks Can Be Managed (continued)Figure 7: The difference between the HTL options
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The draft MEASS recommendationswill only be implemented if sufficientfunding can be found. MEASS doesnot propose detailed schemes nordoes it guarantee that funding isavailable. We have to prioritise wheremoney is spent in order to getmaximum benefit for communities. Werecognise that availability of money islikely to limit the ability to deliver workson the ground.Using the current government process,schemes are given a portion of thefunding required towards to costs, andfurther funding is often required fromthird parties which is called partnershipfunding.
ConsequencesIf funding cannot be found, this can leadto projects identified in the Strategy notbeing taken forward. In MEASS thiscould lead to increased flooding fromovertopping as sea levels rise, as wellas increased risk of collapse and failureof defences, leading to flooding anderosion of the land.
How will Coastal Works be Paid for?
ContributionsWhere proposed works will not attract100% funding from centralgovernment, they can only go aheadby either reducing the costs (potentiallyby accepting a lower standard ofprotection) or if a local contribution isprovided, or a combination of these.Funding partnerships can use localcontributions to unlock national fundingand increase priority, which can meanthat the project can go ahead sooner.These can come through LocalAuthorities, developers, infrastructureproviders or from the Regional Floodand Coastal Committee (RFCC) locallevy.
Figure 8: The River Medway through Rochester Figure 9: Hoo Marina
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Partnership FundingPartnership Funding (PF) approachawards coastal defence schemes apercentage of government funding,based on the degree to which theyachieve specific outcomes. Theoutcomes are based on:• A reduction of flood and erosion
risk (based on the value ofbenefits associated with ascheme);
• The number of properties betterprotected from flood anderosion risk; and
• The creation of new habitats.
Figure 10: Graph explaining how partnership funding allowsmore projects to be progressed.
How does Partnership Fundingwork?• Funds are allocated nationally on
an annual basis.• Each project is given a score to
determine the % of the schemecosts that will be eligible forgovernment funding.
• The rest of the funding will needto be covered by third partyfunders e.g. Local Authorities,developers, infrastructureproviders or from the RegionalFlood and Coastal Committee(RFCC) local levy.
• The government funding receivedcan be applied to any flood andcoastal defence scheme, as longas the shortfall is met from thirdparty contributions.
• This process ensures that taxpayers’ money is spent where itcan deliver most benefit for leastcost.
How will Coastal Works be Paid for?(continued)
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