Coasts

constructive waves properties

strong swash, weak backwash

low height, large wavelength
depositional nature

Destructive waves properties

strong backwash, weak swash
high height, small wavelength
erosional nature

wave size factors

wind strength
wind direction
water depth
fetch distance

define fetch

the length of water over which the wind has travelled

5 coastal processes

erosions

weathering

transportation

mass movement

deposition

5 erosional processes

corrasion

abrasion

attrition

hydraulic action

corrosion (solution)

define corrasion

sand and pebbles are picked up by the sea and hurled against the cliff at high tide , causing the cliffs to be eroded.

define abrasion

sediment scrapes and bangs against the base of a rockface, and so wear away the face gradually

define attrition

wave action causes rocks and pebbles to hit against each other, wearing each other down and so becoming round an eventually smaller.

define hydraulic action

air is forced into cracks within the rock. the high pressure causes the cracks to force apart and widen when the wave retreats and the air expands

define corrosion (solution)

the mildly acidic seawater can cause alkaline rock such as limestone to be eroded. This is similar to chemical weathering

Caves,Arches,Stack & Stumps LEARN THROUGH THE NOTES

nth

WAVE CUT NOTCH AND PLATFORM LEARN THROUGH THE NOTES

nth

define longshore drift

sediment is transported along the coast through the process of longshore drift

LONGSHORE DRIFT LEARN THROUGH THE NOTES

nth

define deposition

when a wave loses energy meaning the sediment becomes too heavy to carry

example of depositional landforms

beaches

spits

bar

define beaches ( if in notes us those)

beaches are large desposits of sand and shingles and are cuased by constructive waves hitting a coastline

SPITS AND BARS IF HAVE NOTES USE THOSE

nth

define embryo dunes

found in the upper beach area where sand starts to accumilate around a small obstacle

define hard engineering:

structures that have been built to alter or to defend the environment.

MAN-MADE

define soft engineering:

those that adapt and encourage natural processes to take place

NATURAL

define groynes:

• wooden barriers constructed at right angle to the beach to retain materials.

• they encourage a wide beach (prevents longshore drift)

• hard engineering

positives and negatives of groynes

negative

• considered unattractive

• hazard for children. Groynes maybe also be a ganger to wind surfers

positive

• can walk along to reach a viewing or fishing point

• relativley cheap and if well-maintained can last up to 40 years

define Gabions:

• Where rocks and boulders are encased in wired mesh and placed at the back of the beach

• they absorb and dissipate energy from waves

• hard engineering

Positives and negatives of Gabions

negatives:

• can be easily destoryed so regular maintenance is required

• people may trip or cut themselves on broken steel wire mesh

positives:

• relatively cheap (£100 a metre) and easy to construct

• blend in better than other hard engineering methods

define sand dunes:

• artificial creation of new sand dunes or restoration of existing dunes

• helps be a physical barrier between the sea and the land

• soft engineering

positives and negatives of sand dunes

negatives:

• regenerated sand dunes are fenced off and signs tell people to keep out. This may deter tourists.

• has to be check twice a years and have fertilisers applied

positives:

• can help maintain a habitat for rare species

• once established , they are popular as picninc and walking areas

define Beach recharge:

• helps with the replacement of lost sediment through longshore drift

• beach recharge - is where shingles is dredged from the seabed and pumped onto the beach

  • soft engineering

positives and negatives for beach recharge

Negatives:

• during re-nourishment access to the beach is restricted for several weeks

• costs a lot (£300,000) to hire a dredger

positives:

• Wider beaches protect expensive properties and reduce sea wall maintenance costs

• it is natural and blends in with the environment

define Beach Reprofiling:

• the artificial re-shaping of the beach using existing beach material to make it wide

• soft engineering

positives and negatives of beach reprofiling:

Negatives;

• can be expensive

• may restrict access to the beach, especially in winter

Positives:

• still looks relatively natural

• residents feel safer with a built up beach

define Rock Armour:

• large boulders placed on the base of the clidd to absorb wave energy

• hard engineering

positives and negatives of Rock armour

Negatives:

• can make access to the beach difficult for people

• it is ugly and covers vast areas of a beach

Positives:

• relatively cheap - £1000 to £3000 a metre

• quick and easy to build

define Sea wall

• usually built along the front of cliffs/back fo beach

• to protect settlement

• hard engineering

positives and negatives of Sea wall:

Negatives:

• ugly to look at and can destroy habitats

• restricts people’s access to the beach

Positives:

• gives people a sense of security

• if well maintained it can last up to 50 years