2.1 Coasts

Dynamic zone

Zone of rapid change with constantly changing inputs and outputs of energy and material

Swash

The forward movement of a wave up a beach

Backwash

The backward movement of water down a beach when a wave has broken

Fetch

Distance a wave travels over

Solution

Where sea water reacts with soluble

Abrasion

Waves lift sand and sediment and throw it at coastline and slowly erode it

attrition

In the sea, sediment is moved over hits other sediments and sediments get smaller and rounder

Hydraulic action

The force of the water breaks rock particles away from the river channel

Prevailing wind direction

The direction from which the wind blows most

often.

Longshore drift

The movement of water and sediment down a beach caused by waves coming in to shore at an angle

headland vs bays

headland=hard rock

bays=soft rock so erodes quicker

wave cut notch platforms

-sea attacks base of cliff

-wave cut notch formed by erosion

-notch increases in size, cliff is unstable so collapses leading to retreat of cliff face

-backwash carries eroded material and leaves wave cut platform

Deposition

when waves deposit material they loose energy, they depose the heaviest material first.

how are caves, arches, stacks and stumps formed

-cracks widen in headland via hydraulic action

-waves grind cracks to form an a cave

-cave becomes larger and breaks to form arch

-base of arch gets wider due to erosion until collapses to form stack

-stack is undercut at base until collapses to form stump

landforms of deposition

spits

estuaries

beaches

spits

areas of beach that only joins to main part of land at one end

form when there is a change in direction of coastline

beaches

pieces of land which separates inland area from a body of water

estuaries

where rivers meet the sea

when there is less water, river deposits silt to form mudflats

Erosion-hydraulic action

-lines of weakness on cliff=vulnerable

-waves reach base of cliff

-air trapped inside cracks

-when waves retreat-explosions of air back into notch

-distinct wave cut notch forms

-cliff is slowly undercut

-large overhang develops

-cliff collapses

-wave cut platform forms

-cliff erodes backwards

Traction

Heavy sediment that settle down on ocean floor

Saltation

Materials bounce along sea bed E.g small pebbles

Suspension

Sediments remain in the water as not heavy enough to settle on the floor but not light enough to float

Solutions

Minerals are dissolved in water and are carried in a solution

Erosion

Processes by which rock, sand, and soil are broken down and carried away

Weathering

The breaking down of rocks and other materials on the Earth's surface.

Chemical examples

Acid rain

Biological example

Plant roots

Permeable rocks

Rocks that allow water to seep through

Impermeable rocks

rock through which liquids cannot flow

Soft engineering

Managing erosion by working with natural processes to help restore beaches and coastal ecosystems

Hard engineering

Building artificial structures such as sea walls aimed at controlling natural processes

Rock armour

Large boulders dumped on the beach as part of the coastal defences.

Recurved sea wall

Wall of concrete which is curved to refract the waves

Groynes

Wooden, stone or concrete barrier built at right angles to the beach.

Gabion

Steel wire mesh filled with boulders used in coastal defences.

Beach replenishment

The process by which sand that was lost through long shore drift or erosion is replaced from a source outside of the beach it was lost from.

Marram grass

type of grass that is adapted to windy, exposed conditions and is used in coastal management to stabilise sand dunes

Wetland creation

Creation of marshes- land that is wet for significant periods of time.

Holderness coast

east coast of england

extends 61km from flamborough head in the north to spurn head in south

2metres of erosion per year

23 towns lost since roman times

Hornsea management strategy

Sea wall and beach replenishment

Mappleton management

- 1991 £2million spent on rock revetments and rock groynes.

Attwick management

No management

Spurn Head, Holderness Coast

example of salt marsh ecosystem - recurved spit shelters mud flats behind it

Wallasea island

NE of southend

lies at heart of internationally- important estuary

lots of farmland but no housing so project was suitable

Wallasea island management

-breached sea walls and the land has been able to flood

Holding the line

Keep current defences and maintaining them

Advance the line

A coastal management strategy which involves pushing the coastline further towards the sea e.g. Bournemouth.

Managed retreat

Allowing controlled flooding of low-lying coastal areas or cliff collapse in areas where the value of the land is low.

Do nothing

Where no action is taken to protect the coastline

conflicted views on management

farmers-want land protected due to farmland

council-want to spend money on services for locals

how might climate affect coastal processes

higher sea levels speed up erosion and attack coastal land

freezing temps also increase weathering

what human activities impact coastal landscapes

cattle farming

tourism

fishing

coastal management

water sports

storm surges

a temporary localised rise in sea level caused by low pressure in atmosphere

how might storm surges influence coastal processes

erosional-increase coastal erosion

transportation- increase longshore drift

depositional-when surges ends=increased deposition

how might geology influence coastal landscapes- Tee-Exe line

-where area of high land meets sea, there will be a cliff

-erosional landforms e.g caves are more common to N and W of Tee-Exe line-harder

-depositional landforms more common in S and E of line-softer

how might geology affect rates of erosion

less resistant rocks=more eroded so more to deposit

HIC coastal community

jaywick

jaywick

north essex

most deprived neighbourhoods

at sea level and at threat of being flooded

protection in jaywick

£10 million project to improve defences

150 steel piles to raise and strengthen sea wall

over 14000 tonnes of rock armour placed in front of sea wall

why is it difficult to manage the consequences of climate change and sea level rise in UK

-economy

-inevitable

-location

-community

-sustainability

LIC coastal communites

Maldives and Tuvalu