Geography UNIT 2 - cOASTAL lANDSCAPES

2 types waves Constructive = Strong swash & small wave( pulls sediment away)

+Destructive = Strong backwash & large wave (wave breaks on beach building sediment )

types of weathering Physical =freeze thaw, Biological = crack, Chemical =RAIN WATER NATURAL ACIDS P38

3 PROCESS USED BY SEA TO ERODE CLIFFS

CORRASION ( abrasion )sand& pepples carried in waves are thrown against cliff face

Corrosion (solution)chemicals in sea water dissolve certain rock types eg chalk

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coastal landscapes

3 differences between soil creep & slumping

Slumping is a large piece of land -which moves suddenly whereas soil creep is small pieces of soil moving almost continuoly . Slumping usually clay cliffs & soil creep is usually with chalk., 

mass movement- sil creep is slowest downhill movement , gravity pulls water in soil downhill , soil particles move with water. heavy rainfall causes faster down hill movement . slope has ripples - called terracettes.

 Formation of cliffs & wave cut platforms

1Sea errodes bottom of cliff using hydralic action forming a notch

2The cliff above the notch forms an over hang - which is pulled down by gravity when it becomes 2 heavy to be supported .

3cliff remaining becomes wave -cut platform  

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coastal erosion

Formation of headlands & bays

If the coast is made up of different rock types with different resistances eg clay & chalk. They will recede at different rates .  This will cause the formation of a headland & a bay- the sea will erode the rocks using corrosion , wearing away the cliffs with pepples at sea . the resistant rock will form a headland & less resistant will form bays

Formation of caves -arches- stacks & stumps

1sea errodes crack with hydraulic action ( water hits the cliff compressing air in cracks- as water retreats the pessure is released breaking off pieces of rock

2 makes crack bigger forming a CAVE .

IF ITS A headland caves will form either side- eventually the backs of caves meet & an arch is formed  overtime the arch collapses - forming a stack

4 the sea uses CORRASION - ie rocks un the sea are thrown against the cliff breaking pieces off the cliff .

5 Arch becomes wider at the bottom &uunable to support weightfrom above - arch pulled down by gravity

6 weathering is active on cliff face - weakening the cliff - over time the sea erodes the bottom of the stack & it collapses to leave a stump

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Long shore drift

Longshore Drift

Movement of sediment along the shore 1 Pebbles r moved in the direction of the prevailing wind . can lead to spits & bars forming .

Longshore Drift Impact

Will deposit matterial in estauries- causing them t silt upif not removed by humans.LSD can remove sand from beaches  

Formation of spits & bars

spits are narrow stretchs of sand & pepples that are joined t the land at one end, bars are spits that go across a bay -only poss with shallow water & no river entering the sea

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Effects of Coastal Recession

Eg Happisburgh

since 1995 - 25 properties lost to the sea , grade1 listed church estimated to be in sea by 2020 .the Tower at Walton on the Naze could be lost to the sea if the cliff continues to errode at 1.5 m a year , . Dawlish Devon Train track washed over by the sea - 160 passengwers stranded 4 hours   

How are the effects of coastal Floods reduced by prediction & prevention

Prediction

Floods can be predicted by forcasting Met office PREDICTS LIKELIHOOD OF FLOOD . weather forcasts get t population by TV, radio , internet site, news

Environment agency monitors sea levels - 24 hrs a day -365 days pa

The storm tide forecasting service - forcasts coastal flooding - 24 hr Flood hot line

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Coastal flooding prediction & prevention

Prevention

Building PLANNING -planning permission not granted to -areas  prone t flood - Build Design- LA malibu coast houses along coast built on stilts to protect them from storm tides

Thames Flood Barrier -2010 environment agency installed new flood walls along the river to protectthe city

Bangladesh - coastal embankment project - 12 sea facing flood walls & 500flood shelters . 

Education -governments give advice by public wesite . BANGLADESH - have flood warning systems . kings lynn in Norfolk - use a flood siren , people employed t go from house t house to help repare for flood  

Floods can be predicted but not prevented because defense systems are built from what is normally experienced - but dont account for exceptional floods every 100 yrs

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Hard & soft engineering

2 disadvants  & 2 advantages of hard engineering

disadvants=Regular maintenance is req  + CAN MAKE THE BEACH INACCESSABLE TO TOURISTS eg Revetments - SLATTED WOODEN STRUCTURES AT BASE OF CLIFFS

ADVANTS - EFFECTIVE FOR YEARS - ABSORBS WAVE ENERGY

GROYNES -ADVANT - effective for many years  ,Disadvantage unattractive difficult t walk on beach

how do groynes defend coastlines

stop the process of longshore drift from removing the sand on the beach . the beach will then take power out of waves& defend the coastline

deifferences between hard & soft engineering

hard = techniques involve majorwork& usually intrusive soft tech work with natural process to work om coastline

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