4.a human activity - intentional - MINEHEAD Flashcards
what is the purpose of intentional activity?
coastal management is an INTENTIONAL CHANGE
planned, deliberate
aim to** protect land behind from floods, retreat, mass movement, threshold events**
with groynes, sea walls etc
why are coastlines managed and how are they managed?
the aim of coastal management is to protect people and the environment from the impacts of coastal erosion and flooding.
however, tough decisions have to be made about where to spend the money and also to consider the impacts of management strategies to the coastal system.
the next step is to come up with a Shoreline Management Plan (SMP)
what is a shoreline management plan?
An SMP oversees a sediment sub-cell.
it assesses the risk to people and the environment and devises a sustainable strategy for flood and coastal defences.
what are the 4 options for managing a coastline?
Do nothing - take no further action
Retreat the line - allow the shoreline to move inshore in a controlled manner (managed retreat/realignment). there is intention here to allow the land behind the coastline to be reclaimed by the sea (often forming a saltmarsh)
hold the line - maintain or sustain the present shoreline using soft and/or hard engineering techniques.
advance the line - use coastal defence works to move the shoreline into areas now covered by the sea. not common but it does hapen in large port cities where space is at a premium.
what is the do nothing coastal management plan?
take no further action
what is the retreat the line coastal management plan?
Retreat the line - allow the shoreline to move inshore in a controlled manner (managed retreat/realignment). there is intention here to allow the land behind the coastline to be reclaimed by the sea (often forming a saltmarsh)
what is the hold the line coastal management plan?
maintain or sustain the present shoreline using soft and/or hard engineering techniques
what is the advance the line coastal management plan?
use coastal defence works to move the shoreline into areas now covered by the sea.
not common but it does happen in large port cities where space is at a premium.
how does a curved sea wall work in coastal management?
this deflects waves and reduces overtopping.
the recurved face rotates the wave backwards so that some of the energy is reflected back at sea.
this impedes the next wave, reducing its energy, and thus its erosive power.
the nature of the wall also prevents all but extreme coastal flooding
how does Rip Rap/rock armour work in coastal management?
a permanent, erosion-resistant ground cover of large, loose, angular stone boulders.
the boulders absorb wave energy and so reduce erosion and flooding
some consideration needs to be given to the size of the boulders and the rock type to ensure resilience
how does (stepped) revetments work in coastal management?
they can be made of wood or concrete (although concrete step now seem to be favoured)
they allow the backwash to lose energy and so encourage deposition building up the beach profile
how do groynes work in coastal management?
these are constructed from a variety of materials, including concrete and wood
they are rarely used on their own and are placed in what is known as a groyne field.
they interrupt LSD so that sand accumulates between the groynes and helps build up the beach profile.
how does managed retreat work in coastal management?
this where the coastline is left undefended, so that the coastal processes may flood the land, often creating a salt marsh.
this then creates a natural buffer to protect land further inland.
it is inexpensive, sustainable and creates good habitat
how does beach nourishment work in coastal management?
sometimes known as beach recharge, this strategy depends on a source of sediment nearby, which can then be dredged and placed on the depleted beach
this builds up the beach and helps create a natural buffer against erosion and flooding.
also helpful for the tourism industry by bolstering the local beach
what is the management strategy Gore point to Hurlstone Point and the justification for it?
MANAGED RETREAT in short and longer term.
low value land
already a salt marsh there
what is the management strategy Selworthy Cliffs and the justification for it?
DO NOTHING
land has no settlements behind/hills behind cliff, therefore not important land to keep safe.
cliffs act as a natural barrier
what is the management strategy Minehead and the justification for it?
HOLD THE LINE by maintaining and improving defences
keep beach wide for tourism
populated, high value land
bay made of mudstones (vulnerable)
3x the amount of beach material on the updrift side of the groyne
sediment provided to Minehead due to slow erosion = increased inputs
what is the management strategy The Warren (golf course) and the justification for it?
Continuing to provide protection by HOLDING THE LINE.
In the long term (as it becomes unsustainable) = managed retreat
not important in ST, but if flooded, massive impact on Butlins
what is the geology of West Somerset?
Porlock Bay = softer Permian Triassic marls
Old Red Devonian Sandstone (quartzite)
Minehead = mudstone
what was the cost of the management strategies in Minehead?
£13.5 mill
what does the socio-economic profile of Minehead rely on?
Butlins
how does Butlins impact Minehead?
main input of income
popular all year round
minehead beach = key attraction for tourists
positive multiplier effect as tourists spend money = creates jobs
what are the advantages of using OS maps?
easy to read/interpret
gives scale = can compare differences and measure
spatially/proportionally accurate
layers of info -physical/human/land uses -rich source of data
how are the groynes impacting the beach profile?
intentionally trapping beach material
3x the amount of sediment on the updrift side of the groynes
building up the beach which acts as a coastal buffer and is also an attraction for tourists
