CoastsCoastsAS RevisionAS Revision

Transportation

Landforms

Classification

Waves

Sand Dunes

Erosion

Importance

Management

COASTS

ImportanceImportance

Why are costs important?Why are costs important?

• Economic sites for industry and Economic sites for industry and fishingfishing

• Habitats and ecosystemsHabitats and ecosystems• Tourism and recreationTourism and recreation• Coastal ProtectionCoastal Protection• Defence and developmentDefence and development

Inter Coastal Zone Inter Coastal Zone ManagementManagement• 1992 – Earth Summit (Agenda 21 1992 – Earth Summit (Agenda 21

Ch.17) Protection of the OceansCh.17) Protection of the Oceans• Climate ChangeClimate Change• 1993 – World Coast Conference1993 – World Coast Conference• All of these and more have pointed to All of these and more have pointed to

the need for sustainable management the need for sustainable management of the diverse issues affecting coasts of the diverse issues affecting coasts todaytoday

• Successful ICZM requires 3 stagesSuccessful ICZM requires 3 stages• Stage One – Development and Stage One – Development and

understanding of systems and understanding of systems and processesprocesses

• Stage Two – Use knowledge to create Stage Two – Use knowledge to create a sustainable long term a sustainable long term environmentally acceptable planenvironmentally acceptable plan

• Stage Three – Implementation and Stage Three – Implementation and enforcement as well as educationenforcement as well as education

WavesWaves• Oceans cover 70% of earth’s surfaceOceans cover 70% of earth’s surface• Coast is the narrow overlap between Coast is the narrow overlap between

land and sealand and sea• Waves and tides are used to divide Waves and tides are used to divide

the coast into zonesthe coast into zones

Waves In Deep WaterWaves In Deep Water• Swell – Often travelled large distanceSwell – Often travelled large distance

Shallow Water WavesShallow Water Waves• when the depth is less than one twenty-fifth of their when the depth is less than one twenty-fifth of their

wavelength wavelength • water particle orbits inside the wave become elliptical water particle orbits inside the wave become elliptical

rather than circular as the “up-down” component of the rather than circular as the “up-down” component of the motion is “squeezed” by the presence of the bottommotion is “squeezed” by the presence of the bottom

Breaking WavesBreaking Waves• Spilling breakersSpilling breakers • Plunging breakersPlunging breakers

Wave RefractionWave Refraction

TidesTides• Oscillations of the sea surfaceOscillations of the sea surface•Tidal movements

ErosionErosion

Action of the wavesAction of the waves

Sub Ariel processesSub Ariel processes

Sub ArielSub Ariel• Those from aboveThose from above• WindWind• RainRain• ColdCold• HeatHeat• HumanHuman

Factors Effecting Rates Of Factors Effecting Rates Of ErosionErosion• Breaking Point of WaveBreaking Point of Wave• Wave SteepnessWave Steepness• Depth of Sea – length of fetch and Depth of Sea – length of fetch and

shape of coastshape of coast• Supply of beach materialSupply of beach material• Beach WidthBeach Width• LithologyLithology

TransportationTransportation

Longshore DriftLongshore Drift

LandformsLandforms• Landforms are created by erosional Landforms are created by erosional

processesprocesses

Wave Cut PlatformWave Cut Platform

TombolosTombolos

Barrier IslandsBarrier Islands• Develop on coasts with high energy Develop on coasts with high energy

waves and low tidal rangeswaves and low tidal ranges

FormationFormation• Seen on eastern coast of North America, where they Seen on eastern coast of North America, where they

extend from New England south to Mexico. extend from New England south to Mexico. • long, narrow, offshore deposits of sand or sediments long, narrow, offshore deposits of sand or sediments

that parallel the coast line. that parallel the coast line. • formation of barrier islands is complex and not formation of barrier islands is complex and not

completely understood completely understood • current theory is that barrier islands were formed current theory is that barrier islands were formed

about 18,000 years ago when the last Ice Age ended about 18,000 years ago when the last Ice Age ended • glaciers melted and receded sea levels rose, flooded glaciers melted and receded sea levels rose, flooded

areas behind the beach ridges areas behind the beach ridges • rising waters carried sediments from those beach rising waters carried sediments from those beach

ridges and deposited them along shallow areas just ridges and deposited them along shallow areas just off the new coast lines off the new coast lines

• Waves and currents continued to bring in sediments Waves and currents continued to bring in sediments • In addition, rivers washed sediments from the In addition, rivers washed sediments from the

mainland that settled behind the islands and helped mainland that settled behind the islands and helped build them upbuild them up

Barrier islands serve two main Barrier islands serve two main functions: functions:

1.1. they they protect the coastlines from protect the coastlines from severe storm damagesevere storm damage..

2.2. they they act as habitats that are act as habitats that are refuges for wildliferefuges for wildlife

Factors affecting landformsFactors affecting landforms

Rock Structure and ShapeRock Structure and Shape

Sand DunesSand Dunes• They grow when sand is deposited on They grow when sand is deposited on

the beach by longshore drift or the beach by longshore drift or shoreward movement of sediment shoreward movement of sediment sand accumulates into ridges which sand accumulates into ridges which originally lie parallel to the direction originally lie parallel to the direction of the prevailing winds of the prevailing winds

• Sand dunes are dynamic elements of Sand dunes are dynamic elements of the landscape the landscape

Pioneer Stage - Pioneer Stage - ForedunesForedunes • pioneer species form on dunes. pioneer species form on dunes.

Tolerant of salt such as Marram grassTolerant of salt such as Marram grass• They stabilize new dunes with their They stabilize new dunes with their

networks of root systems. networks of root systems. • Each plant can also spread sideways Each plant can also spread sideways

by up to 3 metres a year, helping to by up to 3 metres a year, helping to trap the sand and keep it in one trap the sand and keep it in one place. place.

Yellow (White) Dune Yellow (White) Dune StageStage • begin to show a greater diversity of plants as conditions begin to show a greater diversity of plants as conditions

become more favourable become more favourable • As plants die and decay, a humus layer builds up and this As plants die and decay, a humus layer builds up and this

traps both water and nutrients traps both water and nutrients • more shelter and less salt spray. Marram usually still more shelter and less salt spray. Marram usually still

dominates the vegetation dominates the vegetation • Plants may include Plants may include creeping fescue, sand sedge, creeping fescue, sand sedge,

mosses, lichens, sea hollymosses, lichens, sea holly and and sea spurgesea spurge • dunes by this stage may well have reached 5-10 metres in dunes by this stage may well have reached 5-10 metres in

height height • Rabbits and other mammals may add their droppings to Rabbits and other mammals may add their droppings to

help enrich the developing soil help enrich the developing soil

Grey Dune StageGrey Dune Stage • much more stable, mosses and lichens fill the remaining much more stable, mosses and lichens fill the remaining

spaces vegetation cover may reach 100% spaces vegetation cover may reach 100% • Marram grass becomes less common Marram grass becomes less common • Red fescue, sand sedge, sea spurge begin to dominateRed fescue, sand sedge, sea spurge begin to dominate• Small shrubs (gorse, buckthorn) appear for the first timeSmall shrubs (gorse, buckthorn) appear for the first time• 50-100 metres from the sea 50-100 metres from the sea • humus begins to darken the surface layers a true soil humus begins to darken the surface layers a true soil

begins to form begins to form • commonly 10 metres in height and wider than those dunes commonly 10 metres in height and wider than those dunes

nearer the shore nearer the shore

Dune Slacks Dune Slacks • dune slacksdune slacks are found in between the more are found in between the more

mature dunes where the water table reaches mature dunes where the water table reaches the surface causing seasonal or even the surface causing seasonal or even permanent waterlogging and surface water permanent waterlogging and surface water

• Plants which are well adapted to these Plants which are well adapted to these damp, sheltered hollows include damp, sheltered hollows include rushes, rushes, sedges, cotton grasssedges, cotton grass and and creeping creeping willowwillow. If decay is slow, a peaty soil may . If decay is slow, a peaty soil may develop develop

Mature DunesMature Dunes• Most found several hundred metres from the Most found several hundred metres from the

shore shore • these dunes develop a soil which can support these dunes develop a soil which can support

shrubs and trees shrubs and trees • Humans may plant fast-growing conifers which Humans may plant fast-growing conifers which

flourish in the sandy soilflourish in the sandy soil

FragilityFragility

Coastal ClassificationCoastal ClassificationJohnson 1919Johnson 1919• Emergent – fall in sea levelEmergent – fall in sea level• Submergent – rise in sea levelSubmergent – rise in sea level• Stable – no changeStable – no change• Compound – mixture of two of the Compound – mixture of two of the

aboveabove

Shepard 1963Shepard 1963

1.1. Primary – Influence of sea is Primary – Influence of sea is minimal: (fjords [Glaciers], deltas minimal: (fjords [Glaciers], deltas [Rivers], islands Volcanic])[Rivers], islands Volcanic])

2.2. Secondary – Marine processes Secondary – Marine processes dominate e.g.. Headlands and bays, dominate e.g.. Headlands and bays, spits etcspits etc

Valentin 1952:Valentin 1952:

1.1. Advancing – marine depositation or Advancing – marine depositation or uplift of land dominatesuplift of land dominates

2.2. Retreating – Where marine erosion Retreating – Where marine erosion or submerging land dominatesor submerging land dominates

Sea Level RiseSea Level Rise• Thermal Expansion of the oceans – Thermal Expansion of the oceans –

warmer water is less dense than so warmer water is less dense than so occupies greater areaoccupies greater area

• Melting of small alpine glaciersMelting of small alpine glaciers

Tectonic CoastsTectonic Coasts Inman and Nordstrom Inman and Nordstrom 1971:1971:

1.1. Diverging plates - Red SeaDiverging plates - Red Sea2.2. Converging plates – Island arcs Converging plates – Island arcs

Japan and PhilippinesJapan and Philippines3.3. Major transform faults - CaliforniaMajor transform faults - California4.4. Stable plate boundaries – India and Stable plate boundaries – India and

AustraliaAustralia

Energy Produced Coastlines Davis 1980Energy Produced Coastlines Davis 1980

• High Energy environments – Where High Energy environments – Where destructive waves are more typicaldestructive waves are more typical

• Low energy environments – Where Low energy environments – Where constructive one prevailconstructive one prevail

• Protected Environments – Wave action Protected Environments – Wave action is limitedis limited

Coastal ManagementCoastal Management

Case StudiesCase Studies• Holderness – Coastal ErosionHolderness – Coastal Erosion• Formby Sand - DunesFormby Sand - Dunes• N. Carolina - Barrier islandsN. Carolina - Barrier islands