- Created by: Craig White
- Created on: 16-05-14 13:54
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
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 .
Long shore 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
Effects of Coastal Recession
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
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
Coastal flooding prediction & 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
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