2B.11 Coastal Management Flashcards
2B.11a Hard engineering
general
Hard engineering is
The aim is to directly stop physical processes altogether (such as erosion or mass movement) or alter them to protect the coast (such as encouraging deposition to build larger beaches)
2B.11a Hard engineering
advantages of hard engineering
It responds to the demand for action from stakeholders
It can protect the most vulnerable coastlines and completely eliminate the threat
2B.11a Hard engineering
disadvantages of soft engineering
extremely expensive and ongoing maintenance costs
coastlines are made visually unattractive
the needs of the ecosystem are usually overlooked
defences built in one place frequently have adverse consequences further along the coast (promontory effect)
2B.11a Hard engineering
Groynes
vertical stone or timber ‘fences’ built perpendicular to the coast and spaced along the beach
purpose:
prevents longshore movement of sediment and encourage deposition, building a wider higher, beach
impact:
deposition and beach accretion
prevention of longshore drift, sediment starvation and increased erosion downdraft
cost:
£150-250 per metre
2B.11a Hard engineering
Sea Wall
concrete with steel reinforcement and deep-piled foundations; can have a stepped and/or ‘bullnose’ profile, to dissipate wave energy
purpose:
a physical barrier against erosion
they often also act as flood barriers
modern sea walls are designed to dissipate, not reflect, wave energy
impact:
destruction of the natural cliff face and foreshore environment
if reflective, it can reduce beach volume
cost:
£3000-10,000
2B.11a Hard engineering
Rip Rap (rock armour)
large igneous or metamorphic rock boulders, weighing several tonnes
purpose:
their purpose is to break up and dissipate wave energy
often used at the base of the sea walls to protect them from undercutting and scour
impact:
reduced wave energy
sediment deposition between rocks
may become vegetated over time
cost:
£13,000-6000
2B.11a Hard engineering
Revetments
stone, timber or interlocking concrete sloping structures which are permeable
purpose:
to absorb wave energy and reduce swash distance by encouraging infiltration
reduce erosion on dune faces and mud banks
impact:
reduced wave power
can encourage deposition and may become vegetated
2B.11a Hard engineering
Offshore Rock Breakwater
large igneous or metamorphic rock boulders weighing several tonnes (offshore rip-rap)
purpose:
forces waves to break offshore, rather than at the coast, reducing wave energy and erosive force
impact:
deposition encouraged between breakwater and beach
can interfere with longshore drift
2B.11b Soft engineering
a
2B.11b Soft engineering
general
attempts to work with natural physical systems and processes to reduce the coastal erosion and flood threat
2B.11b Soft engineering
advantages of soft engineering
less obvious and intrusive at the coast
2B.11b Soft engineering
disadvantages of soft engineering
not suitable for all coasts
2B.11b Soft engineering
beach nourishment
artificial replenishment of beach sediment to replace sediment lost by erosion, enlarge the beach, dissipate wave energy and reduce erosion, increase the amenity value of the beach
£20 million per km of beach
ongoing costs are high
sediment must not be sourced from elsewhere in the sediment cell
2B.11b Soft engineering
cliff regrading and drainage
cliff slope angles reduced to increase the stability
re-vegetated to reduce surface erosion
in-cliff drainage reduces pore-water pressure and mass movement risk
costs £1 million per 100m
can be disruptive during construction
2B.11b Soft engineering
dune stabilisation
fences are used to reduce wind speeds across the dunes
dunes are then replanted with marram and lyme grass to stabilise the surface, reducing wind and water erosion
fencing costs $400-2000 per 100m and replanting £1000 per 100m
can be very cost effective in the long term
2B.11b Soft engineering
a
2B.11c Sustainable Coastal Management
sustainable coastal management- managing the wider coastal zone in terms of people and their livelihood, social and cultural well-being, safety from coastal hazards as well as minimising the environmental impacts
2B.11c Sustainable Coastal Management
methods
managing natural resources (fish, farmland, water supply) to ensure long-term productivity
managing flood and erosion risk where possible, or relocating to safe areas
creating alternative livelihoods before existing ones are lost to the sea
adapting to sea level rise by relocating, alternative building methods and water supplies
educating communities to understand why change is needed and how to adapt
monitoring coastal change and adapting to unexpected trends
2B.11c Sustainable Coastal Management
causes of conflict
coastal natural resources may have to be used less in order to protect them- so people lose income
relocation may be needed where engineering solutions are costly or not technically feasible
some erosion and/or flooding will always occur, as engineering schemes cannot protect against all threats
future trends, such as sea level rise, may change, creating uncertainty and the need to change plan
2B.11c Sustainable Coastal Management
Integrated Coastal Zone Management (ICZM)
The idea of ICZM was introduced at the 1992 Earth Summit meeting and aims to bring together economic decision-makers such as tourism, fishing and ports, and different government levels (including international). other aims include the conservation of coastal ecosystems, ensuring the ability of future generations to use the coast and the involvement of all relevant stakeholders
ICZM emphasises cooperation between all stakeholders so that everyone benefits. It is a dynamic process because of changing demands at the coast, and decisions are likely to be increasingly concerned with vulnerability and sustainability.
The EU adopted the Recommendation on ICZM in 2002, and Maritime Strategy Framework Directive of 2008 also emphasised a comprehensive and integrated approach to protect all European coasts and seas. ICZMs can now be found worldwide, at varying states of sophistication and with various levels of action
