P1C Physical Landscapes

what causes waves

transfer of energy from the wind to the sea

what are the factors that determine the strength of the waves (3)

speed of the wind

how long the wind has been blowing

the fetch

label the points of the wave

crest - the top of the wave

trough - the base of a wave

wave height

wave length

wave frequency

what are constructive waves

found in sheltered bays where they build up sandy beaches

what are destructive waves

found in more exposed bays where they build up pebble beaches

characteristics of a constructive wave

strong swash

weak backwash

characteristics of destructive waves

restricted swash

very strong backwash

what are the types of weathering processes

chemical

mechanical

what are the types of chemical weathering (3)

carbonation

• carbonic acid in rainwater reacts with calcium carbonate in limestone to form calcium bicarbonate - this is soluble so limestone is carried away in solution

hydrolysis

• acidic rainwater breaks down rock causing it to rot

oxidation

• rocks are broken down by oxygen and water

what are the types of mechanical weathering (2)

freeze thaw weathering

• water enters crack

• freezes and expands (increases volume by 9%)

• makes the cracks wider

salt weathering

• salt spray from the sea goes into crack

• may evaporate and crystallise, weakening the structure

how does mass movement happen (3)

sliding

• downhill movement of large amounts of rock, soil and mud (sometimes rock slides)

rock falls

• like sliding but vertical - literally falling - usually found on vertical cliffs

slumping

• concave slip plane (literally slumping - part of cliff closest to water)

erosional processes (3)

hydraulic power

• relentless force of destructive waves pounding on the base of cliffs

abrasion

• sand and shingle is hurled at a cliff from the water causing pieces to eventually fall

attrition

• the grinding of load particles during transport , pebbles collide with each other

transportation along the beach?

long shore drift

• direction is determined by the prevailing winds

• OTHER THAN THAT LONG SHORE DRIFT

what conditions cause deposition (4)

low energy

large sources of sediment updrift

where there are large expanses of flat beach

where engineered structures like groynes trap sediment

draw concordant and discordant coast lines and explain what each of them create

create headlands and bays

what is a headland

cliff that juts out into the sea - composed of hard rock such as granite chalk or limestone

what are the characteristics of a headland (5)

near vertical cliff face

high energy areas affected by destructive waves

hard rock jutting out into sea

caves forming in its sides

stacks and stumps

what is a bay

crescent shapes indentation in the coastline found between two headlines - usually has a beach composed of sand or shingle

what are the characteristics of a bay

soft rock such as sand and clay

low energy constructive waves

more sand accumulation in the down drift in the north section due to LSD

2 headlands marking the edge of the bay

what are headlands and bays formed

explain starting from discondordant coasts

state and explain the different types of transportation

traction

• large, heavy pebbles are rolled along the sea bed

saltation

• pebbles are bounced across the sea bed

suspension

• lighter sediment is carried within water

solution

• transport of dissolved chemicals

what is a wave cut platform

flat rocky area found at the base of a retreating cliff left behind as the cliff erodes and retreats

characteristics of cliffs

near vertical slope

made of rock layers

characteristics of wave cut platforms

flat

extends out from base of cliff

often has rock pools

formation of a cliff and wave cut platforms (8)

• land slopes down to the sea - weathering weakens rock

• marine erosion is concentrated between high and low watermark

• wave pounding by hydraulicpower and hurled shingles erode base

• continued erosion at base - now has notch at its base

• section above notch can be weakened easier now

• eventually notch is too large - gravity - section break of into beak

• resulting steep drop is called a cliff

• cliff reatreats and wave cut platforms expands and becomes smoother due to grinding shingle

how are caves arches and stacks formed (8)

large crack is enlarged by hydraulic action

crack grows into notch and then cave due to destructive waves and erosional processes

cave becomes larger and becomes arch

weathering weakens top of arch making it less stable

top of arch collapses

leaves a pillar called a stack

notches forms at base - make it unstable

stack will topple leaving a stump normally inly visible at low tide

characteristics of an arch

unsupported top of the arch

wave cut notches at the base of the arch - base = wide

extension of headland

characteristics of stacks

detached pillars located off a headland

often several metres high

hard rock

wave cut notches at base

characteristics of a sand beach

• gradient is shallow - almost flat

• contructive waves are dominant

• distance stretches inland is a long way

• sometimes can get sand dunes at back of beach

characteristics of pebble beaches

• gradient is generally steep

• destructive waves are dominant

• storm beach with large pebbles at back of the beach

what do sand dunes need to form

large flat beach

large supply of sand

large tidal range - time for sand to dry

onshore wind

obstacles such as drift wood

order of types of sand dunes

embryo dune - wood - seaweed

fore dune - marram grass

yellow dune - marram grass

grey dune

dune slack

mature dune - trees

characteristics of spits

large hook

mudflats and salt marshes

pebbles become progressively smaller towards distal end

how are spits formed

longshore drift carries sand away and along the beach in a hook formation until the water is too deep

characteristics of bars

long and narrow ridge of sand or shingle

forms across a bay

creates a lagoon

how bars are made

LSD moves sediment along coast

waves deposit materials across a bay between two headlands

ridge extends further across the bay

joins to headlands

what is hard engineering

artificial structures are used for protection - they do not blend well but are effective

what are the 4 types of hard engineering for coastal management

sea walls

groynes

rock armour

gabions

what is a sea wall

provide a barrier between waves and the land

along back of the beach

recurved sea walls are more expensive than flat sea walls but are more effective in reflecting waves

steps are often added for more stability

the curved face allows some of its energy to be exerted on the wave when it collides so when the wave goes back it impredes the next wave

what are groynes

wooden or stone structures built in foreshore - look like fences or walls

built at right angles and are spaced regularly apart - (usually around 50 m)

trap sediment transported by LSD

groynes are particularly effective when used in conjunction with beach nourishment

what is rock armour

thousands of tonnes of huge boulders of hard rock like granite to act as a barrier between see and land

as water enters the gaps pressure is released and this reduces the wave’s energy so theres little scouring of the base

what are gabions

steel wire mesh cages filled with pebbles or rocks

back of sandy beaches to create low wall structure

water enters cage and this dissipates some of wave’s energy

reduces rate of erosion

can also be places in front of cliffs where it reduces risk of landslides

what are the social benefits of sea walls

gives people a sense of security

often has promenade on top - cycle route

steps at base can act as seating areas

social benefits of groynes

act as wind breaks

walk along to reach fishing or view points

social drawbacks of sea walls

restrict peoples access to beach

if waves break sea wall - coastal flooding may occur

social drawbacks of groynes

dangerous - deep water on one side and shallow water on the other - hazard for children

hazard for wind surfers who can collide with them

social drawbacks of rock armour

makes access to the beach difficult - people have to go over it or take long detours

if rocks are regularly covered by tide - they may collect slippery seaweed

social drawbacks of gabions

in a damaged state gabions are dangerous - people may trip over or cut themselves on broken stele mesh wire

what are the economic benefits of sea walls

if well maintained the walls can last for many years

what are the economic benefits of groynes

at £5000 each groynes are relatively cheap and if well maintained can last up to 40 years

a larger beach attracts more tourists and boosts the local economy

what are the economic benefits of rock armour

costs £1000 - £3000 per metre - structure is easy to build and maintain - can be built in weeks rather than months - if well maintained rock armour can last a long time

what are the economic benefits of gabions

a £110 a metre they are relatively cheap and easy to construct

they are usually constructed on site with local pebbles

allows for a quick easyfix situation and if well maintained they last for around 20-25 years

what are the economic drawbacks for sea walls

around £5000 per linear metre

repairs are also expensive

if repairs aren;t fixed quickly there can be devastating consequences

to reduce scouring rock armour and beach nourishment may be needed which will add more to expenses

what are the economic drawbacks of groynes

restrict the supply of sediment down - drift

groynes are ineffective in stormy conditions and need regular maintenance so they dont rot

economic drawbacks of rock armour

heavy storm waves will move rocks so they need regular maintenance

rocks are usually imported from sweden and norway in preference from those in local quarries which may cause resentment and increase costs

economic drawbacks of gabions

restricted to sandy beaches

easily destroyed - regular maintenance

the gabions built at thorpeness, suffolk in 1976 cost £30 000 to repair them in 2010

environmental benefits for sea walls

do not impede the movement of sediment downdrift so they don’t disadvantage other areas

environmental benefits for rock armour

can be placed in front of sea walls to lengthen its lifespan

environmental benefits for gabions

blend in better especially when sand is blow into them or they are covered by vegetation

environmental drawbacks of sea walls

from the beach, a wall of concrete is ugly to look at

sea walls can also destroy habitats

environmental drawbacks of groynes

groynes may be considered unattractive, especially degraded ones

environmental drawbacks of rock armour

ugly and usually covers vast areas of the beach

driftwood and litter or rubbish become trapped in the structures and do not blend in with the local geology

environmental drawbacks of gabions

damaged gabions are unsightly and sea birds may damage their feet in them

what is beach nourishment

replacement of lost sediment

a nourished beach means fewer waves reach the back of the beach

• more wave energy is absorbed by the beach

• rate of erosion is reduced

what are the two ways of beach nourishment

beach recharge

beach recycling

what is beach recharge

sediment is taken from a bay and is placed on a beach which is losing sand

what is beach recycling

removal of sand from a down drift area which is building up sand and returning it up drift

what is beach reprofiling

artificial reshaping of a beach using existing beach material

in winter a beach is lowered by destructive waves

after winter storms bulldozers move shingle back up the beach

like beach nourishment reprofiling ensures that the beach is large enough to be an effective buffer between land and sea

what is sand dune regeneration

artificial creation of new sand dunes or the restoration of existing ones

sand dunes act as a physical barrier between the sea and the land

they absorb wave energy and water

in this way they protect the land from the sea

what are the social benefits of beach nourishment

a wider beach means more room for beach users

people living along the seafront are more protected from coastal flooding

what are the social benefits of beach reprofiling

A Pevensey residential area behind the beach is now protected so the residents feel safe

what are the social benefits of sand dune regeneration

sand dunes protect land uses behind them

once established, they are popular as picnic and walking areas

what are the social drawbacks of beach nourishment

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

beach recycling may cause resentment from residents living closer to the donor area

what are the social drawbacks of beach reprofiling

bulldozers restrict access to pevensey’s beach especially in winter

what are the social drawbacks of sand dune regeneration

while becoming established regenerated sand dunes are fenced off and signs tell people to keep out

this may deter tourists

what are the economic benefits of beach nourishment

at sandbanks the wider nourished beach protects very expensive properties

the buffer of a widened beach reduces sea wall maintenance costs

a broader beach may also attract more tourists

what are the economic benefits of beach reprofiling

if the shingle ridge at pevensey is breached the estimated repair cost would be about £125 million

the combined costs for nourishment and frequent profiling is £30 million over 25 years

what are the economic benefits of sand dune regeneration

small planting projects usually use volunteer labour and local grass for transplants so costs are minimal

what are the economic drawbacks of beach nourishment

although cheaper than hard engineering - this costs around £300 000 to hire a dredger

what are the economic drawbacks of beach reprofiling

major reprofiling costs can be expensive

£200 000 a year was paid to realign the beach prior to the Medmerry scheme

what are the economic drawbacks of sand dune regeneration

dune regeneration has to be checked twice a year and have fertilisers applied

expensive systems have to be put in place to protect planted areas from trampling

what are the environmental benefits of beach nourishment

a nourished beach is natural and blends in with the environment

what are the environmental benefits of beach reprofiling

in preventing a breach the pevensey levels has been protected and the beach still looks reasonably natural

what are the environmental benefits of sand dune regeneration

at studland sand dune regeneration has heped maintain a habitat for rare dartford wabblers, night jars and chiffchaffs

what are the environmental drawbacks of beach reprofiling

a steep high crested beach may look unnatural and uninviting to tourists

what are the environmental drawbacks of sand dune regeneration

once regenerated theres no guarantee they will be stable

the grass may soon be damaged by storms and even in favourable conditions it will take two to three years before grasses become established and begin to spread

how does a river erode and what does each process do (4)

hydraulic action - sheer force of fast flowing water

abrasion - small boulders and stones may scratch and scrape their way down a river during transport

solution - dissolving of rocks such as chalk and limestone

attrition - rock = jagged and angular - collides and become smooth oval

how does a river transport its load

solution

saltation

suspension

traction

different parts of a long profile

upper course

• has a very steep v shaped valley

• vertical erosion

• very steep gradient

• narrow shallow channel

• low velocity

• small discharge

• rough river bed

• large angular rocks on the bed

middle course

• broad valley

• gradient less teep

• lateral erosion more than vertical erosion

• channel is wider and fairly deep

• fairly high velocity

• quite high discharge

• river bed less rough

• river bed sediments smaller and smoother

lower course

• has a very broad valley

• very gentle gradient

• very wide valley

• mostly deposition

• very wide and deep

• high velocity

• high discharge

• smooth river bed

characteristics of interlocking spurs

steep gradient

project from alternate side of the valley

separated by narrow valley floor mostly taken up by river channel

characteristics of a waterfall

plunge pool

hard rock on top - soft rock on bottom which erodes faster

characteristics of a gorge

• very narrow valley

• high valley sides

• fast flowing white water

how does a waterfall mke a gorge

as water fall retreats it leaves a steep sided valley downstream which is called a gorge

everytime the overhanging cap rock breaks the waterfall retreats and the gorge grown longer

how is a meander made

have to mention hydraulic action and abrasion

how are oxbow lakes formed

include fact that marsh plants colonise the area

what are levees

naturally raised riverbanks found in either or both sides of a river channel that is prone to flooding

characteristics of levees

have raised riverbanks

composed of gravel and stones

steep sides

fairly flat top

how are levees made

during floods sediments is deposited on river banks with the largest closest and the smallest furthest

after every flood they go higher

characteristics of a flood plain

flat land

fertile soil

wildlife habitat

how is a flood plain made

same thing as a levee but over hundreds of years to make a whole area of land - it is fertile due to the supply of silt and alluvium caused by river flooding