3.1.3.4 Costal Managment

How much of the population live within 60km of the coast and what % of large cities are costal

50% of the population, 75% of the large cities

Hard engineering

Traditional, mechanical approach of man made structures and technology to control costal processes

Hard engineering advantages

Immediate, effective in high energy coastlines, long lifespan

Hard engineering disadvantages

Expensive, visually intrusive, increase erosion elsewhere, disrupt sediment budget equilibrium

Reasons for intervention (with example)

Resilience against natural hazard, protect high value infrastructure (29% UK natural gas from Easington), managing population pressure, preserve costal ecosystems

Cost benefit analysis

Forecasts total expected costs against total expected benefits for environment and population. DEFRA suggest a 1:1 ratio

Tangible costs/benefits in the CBA

Things with a known monetary value. Land/house market value saved. Design, construction, maintenance

Intangible costs/benefits CBA

Difficult to asses but hold value. Preservation of scientific interest, spirit of a place. Visual impact, loss of identity, disrupt geology

Hard engineering types

Groynes, Sea wall, Rock armour, Revetments, Offshore breakers

Groynes

Timber structures built perpendicular to the coast trap longshore drift and build up beach

Groynes evaluation

Relatively cheap (>10K), built up beaches attract tourists, beach absorbs wave energy. Requires maintaince, visually unattractive, sediment starvation, terminal groyne syndrome

Sea walls

Concrete walls at the foot of a cliff with curved surface to reflect wave energy

Sea wall evaluation

Highly effective, tourism benefit, long lifespan. Very expensive (6K/M), visually intrusive, erosion downdrift, reduce sediment budget to create small beaches

Rock armour

Permeable barrier of boulders at foot of a cliff which reduce/dissipate wave energy

Rock armour evaluation

Relatively cheap (<3k/m), easy to construct/maintain, recreational benefits. Non local geology intrusive, safety hazard, disrupt sediment cell (reduced littoral cell input), erosion downdrift

Revetments

Sloping ‘ramp like’ structures break up/absorb incoming wave energy

Revetments evaluation

Relatively cheap (4.5k/m), effective energy dissipation. Visually intrusive, maintenance required, reduced sediment (from erosion) into littoral cell causes downdrift erosion

Offshore breakers

Rock barriers pararrell to the shore but out to sea forcing waves to break early

Offshore breakers evaluation

Energy reduction, tourism neutrality, artificial reefs support marine life. Navigation hazard, interfere with longshore drift (sediment starvation), visually unappealing

Soft engineering

Utilise natural processes and materials to protect coastal areas and methods to mimic natural ecosystems

Soft engineering advantages

Environmentally friendly/sustainable, cost effective, natural aesthetic

Soft engineering disadvantages

High maintenance, vulnerable to storms/humans, sometimes time consuming

Soft engineering types

Beach nourishment, cliff regrading/drainage, dune stabilisation, marsh creation

Beach nourishment

Adding dredged sand/shingle to increase beach width/elevation to acts as a buffer zone

Beach nourishment evaluation

Natural aesthetics, tourist potential, relatively inexpensive (£3k/m). High maintenance, dredging seabed disrupts ecosystems

Cliff regrading/drainage

Reducing angle of a cliff making it less likely to collapse and removing excess water to reduce pore pressure

Cliff regrading/drainage evaluation

Cost effective, reduces mass movement, effective on clay/loose rocks. Flat slope creates cliff retreat, looks unnatural, sudden rock collapse/fall

Dune stabilisation

Pioneer species (Marram grass), fencing off/boardwalks stabilise dunes and allow plants to develop

Dune stabilisation evaluation

Environmentally friendly/sustainable, creates habitats, cost effective (>£20/m). Fragile to storms/humans, temporal lag, fencing causes stakeholder conflict

Marsh creation

Deliberate breach of defences for flooding to create saltmarsh ecosystems

Marsh creation evaluation

Natural flood buffer, biodiversity increase (vegetation succession), economically sustainable. Loss of farmland, stakeholder conflict, habitat disturbance

SMP (Sustainable management plans)

Holistic, systems based framework identifies sustainable management actions for the 11 sediment cells whilst considering knock on DE effect

SMP positive evaluation

Evidence based from modelling, gives long term clarity through prediction, clear and strategic framework

SMP negative evaluation

Winners and losers from economic bias, not legally binding, sediment cell boundaries don’t match political boundaries

Four policy options in SMP

Hold the line, advance the line, managed retreat, do nothing

Advance the line

Extend coastline seaward by building up beaches

Managed reatreat

Allow coastline to deliberately breach defences and move landward (such as salt marshes)

Integrated Coastal Zone Management (ICZM)

Holistic approach where large sections of the coastline are managed with multiple coordinated strategies

What does the ICZM consider

Political, environmental (DE knock on), social and economic factors

Strengths/aims of the ICZM

Prioritises sustainability, resolves stakeholder conflict, creates opportunities for social/economic growth, long term holistic approaches with cross boundary coordination

Weaknesses of ICZM

Conflicting interests can slow process, benefits uneven for low value land, expensive due to monitoring

ICZM example

2013 EU initiative emphasises ‘ecosystem based’ approach