Coasts

What does littoral mean?

near shore

what are the 3 coast types

• cliffed

• sandy

• estuarine

coastal dynamic equilibrium

the understanding that coasts are systems with both positive and negative feedback

what is the difference between a high and low energy coastline?

high energy coast lines have more erosion occurring resulting in erosional landscapes but low energy coastlines have depositional landforms

what are the four ways of classifying coastlines

• by their formation process

• by their change in sea level

• their tidal range

• their wave type

what is the difference between primary and secondary coastlines

primary coastlines are formed by land based processes such as lava flows but secondary are formed by marine processes such as erosion or deposition

what type of coastline is formed when the sea level drops

emergent

what type of coastline is formed when the sea level rises

submergent

waves…

can be constructive or destructive

depend on-

• wind strength

• water depth

• wave fetch (distance wave travels) hard or

what is weathering?

the insitu breakdown of rocks

what is erosion?

the wearing away of the land surface and removal of materials by river and seawater, ice or wind.

erosional landforms

• cliffs

  → wave cut notch and platforms

• headlands and bays

• CCASS (crack, cave, arch, stack, stump)

what is transportation?

the movement of sediment due to waves

long shore drift

the movement of sand and small stones along the coast by waves travelling at an angle to the coast.

what is deposition?

the dropping of sediment when waves loose tehri energy

depositional landforms-

• beach

• spit

cuspate foreland

sand and shingle accumulated by long shore drift that extends outwards from the shoreline in a triangular shape.

tombolo

a spit or bar that connects to an island

sand dune succession

CASE STUDY - sand dunes

salt marsh (halosphere) succession

CASE STUDY- salt marsh

the blackwater estuary essex

what is the rough trend in rock type across the uk

above the tees-exe line is old sedimentary rock with some igneous patches. Scotland is mostly metamorphic and the south is sedimentary exception being Cornwall (igneous)

what are the 4 types of erosion?

Abrasion, Attrition, Hydraulic action, Solution

what is beach morphology?

the shape of a beach and its characteristics as well as the processes leaving to that

what are the different coastal zones

• littoral zone (near shore, sunlight penetrates sediment so life can flourish, but is most rapidly changing)

• nearshore (near to sea)

• back shore (waves only reach during very high tides)

• off shore (out AT sea)

Sub-aerial processes

weathering and mass movement (any process that does not involve the sea)

weathering

the insitu breakdown of rocks

name the types of mechanical weathering

• freeze thaw

• salt crystallisation

what type of rock is more at risk of mechanical weathering?

porous and cracked rocks

name the types of chemical weathering

• carbonation (most important)

• hydrolysis

• oxidation

what is carbonation?

Rainwater abosorbs CO2 and becomes more acidic. allowing it to dissolve rocks such as limestone

what is hydrolysis?

water breaks down igneous and meta rocks to form clay

what is oxidation?

when oxygen reacts with compounds in the rock(eg iron) and increase the volume causing breakdown of the rock

name the types of biological weathering

• plant roots

• rock boring

what is rock boring?

when clams and molluscs bore into rock and may also secrete chemicals that dissolve rocks.

name all 5 types of mass movement

• rock falls

• rock topples

• transitional landslides

• rotational landslides (slumping)

• mudflows

what is formed as a result of rockfalls?

scree talus slopes (a slope of material that has fallen vertically from a cliff)

what can be the cause of rock topples?

joints in the rock and their location

if bedding plane is parallel to the surface, what mass movement may occur?

sliding

what conditions increase the risk of slumping?

• saturated conditions

• permeable rock layer on top of impermeable rock layer

what can be formed as a result of slumping?

• rotational scars

• Terrance cliff profile (areas of grass lowing down like steps as a result f repeated slumping)

how are mudflows different to sliding?

slides stay intact whereas mudflow material becomes mixed up

what are the two types of sea level change?

isostatic change and eustatic change

what is isostatic sea level change

change in sea level due to the rise and fall of land

what is eustatic sea level change

change in sea level due to water volume change

what can cause isostatic change?

ice caps-

• are heavy and cause land to sink

• but when they melt land moves back up gradually (isostatic rebound)

what causes eustatic change?

• thermal expansion

• ice caps melting

what is the difference between marine regression and transgression?

marine regression is when an emergent coastline if formed due to sea level fall. but marine transgression produces a submergent coastline due to sea level rise

name the landforms created due to marine regression

• raised beach

• fossil cliff

name the landforms created due to marine transgression

• ria (flooded riVer valley)

• fjord (flooded glacier/ u shaped valley)

• Dalmatian coast

case study for sea level change is....

kiribati

flooding case study

bangladesh

flooding case study

UK in 1953 and then again in 2012 ‘the north sea flood’

sediment cells

A length of coastline within which the movement of sand and shingle is largely self-contained (dynamic equilibrium)

coastal management

protecting coastlines from threats such as erosion or transportation

coastal defences types

hard or soft engineering

coastal defence soft engineering examples

• beach replenishment (adding sediment to a beach)

• cliff regrading (reducing angle of cliff to stabilize it)

  → and drainage (removed water to prevent slumping)

• dune stabilisation (planting marram grass)

• marsh creation (managed retreat - allowing lowlying areas to be flooded)

• planting mangroves

CASE STUDY- flooding management using mangroves

Bangladesh and sri lanka

CASE STUDY - flooding in the uk

uk storm surges

cyclone xavier

coastal defence hard engineering examples-

• groynes

• sea walls

• rip rap

• revetments (wooden or concrete sloping structured that reduce wave power)

• offshore breakwaters (boulders placed offshore under water)

sustainable coastal management

managing coastline to maintain for today without causing damage in the future

holistic strategies

strategies used to please as many stakeholders as possible

cost- benefit analysis

comparing the total costs to the total expected rewards of undertaking a project

environmental impact assessment

the assessment of the environmental consequences of a project

ICZM strategies / SMP (shoreline management plans)

plans and management schemes on shorelines- balancing SEE impacts eg, jobs, biodiversity and erosion

but are not gov run so are not technically compulsory

SMPs can be used holistically by

• involving all stake holders

• making plan long term

• work alongside natural processes

• opportunity for plans to be changed if needed

• consider culture/ heritage of area and ecological value

SMP 4 policies and CASE STUDIES

1. hold the line Eg brighton sea wall

2. no active intervention (do nothing) Eg durdel door

3. advance the line eg salt marshes in kent

4. strategic realignment (retreat the line) Eg Abbots Hall farm

CASE STUDIES for SMPs

• holderness coast (impacts of SMPs)

• happisburg (no active intervention)

• sussex kent and dorset sediment cells