coasts case studies

Example of each of the 3 types of coastal landscape

Rocky/ coiffed coastline (white chiffs of Dover).

Sandy coastline (Bamburgh).

Estuarine coastline (seven estuary)

Example of 2 types of concordant coastline

Dalmatian coast (Croatian Dalmatian coast).

Haff coastline (chesil beach, Dorset)

Example of a type of discordant coastline

Headlands and bays (swanage bay)

5 types of geological structure

Bedding planes, jointing, dip, faulting, folding

Example and 5 stages of veg stabilising a sandy coastline. Psammosere= dune successional development

E.g. Dawlish warren.

Embryo dune (xerophytes (pioneer species) e.g. sea conch grass).

Fore dune.

Yellow dune (marram grass).

Grey dune (a fixed dune. Above tide so less saline. Hummus from dead plants).

Mature dune (climax community which is usually oak Forrest’s in the uk)

Example and 5 stages of veg stabilising an estuarine coastline. Halosere= salt marsh successional development

Algal stage (blue green algae binds mud).

Pioneer stage (halophytes e.g. cord grass).

Establishment stage (thicker mud, less water, height increasing, only submerged by spring tides).

Stabilisation (less hardy plants e.g. sea lavender).

Climax community (rainwater washes salt out of high salt marsh soil for plants to colonise to reach climax community)

6 landforms crested from marine processes of erossion

Headlands, bays, e.g. swanage.

Wave cut notch, wave cut platform, cliffs, cave- arch- stack- stump sequence, e.g. old Harry’s rocks

6 landforms created by processes of sediment transport

Beaches.

Recurved snd double spits (Dawlish warren)

Offshore bars (Slapton sands).

Barrier beaches and bars (chesil beach).

Tombolos (st ninian’s tombolo in Scotland).

Cuspate forelands (Dungeness)

3 landforms of mass movement

Talus scree slope- by block fall.

Rotational scar- by rotational slumping.

Terraced cliff profile- by rotational slumping

Sediment cell example

Sediment cell 2 (NE coast) source region= flanborough head. Transfer zone= holderness coast. Sink region= spurn head.

Positive feedback e.g. major erosion of spurn head spit could lead to increased deposition offshore, creating an offshore bar that reduces wave energy, allowing the spit to recover.

Negative feedback e.g. raised sea levels could increase the erosion of spurn head spit, removing sediment faster than its replaced

Explain eustatic change

Fall or rise in global sea level.

Eustatic fall in sea level happens in glacial periods where water evaporated from the sea wound up locked on land as ice, leading to global fall in sea level, as the oceans volume has decreased.

Eustatic rise in sea level happens at the end of glacial periods where melting ice sheets return water to the sea, raising global sea levels. OR when global temp increases, causing the volume of ocean water to increase( thermal expansion) leading to sea level rise. OR tectonics can cause it. Rising magma at constructive plate boundaries lifted the overlying crust, reducing the capacity of the ocean, rising sea level.

Explain Isostatic change

fall or rise in local land level.

Isostatic fall happens due to post glacial adjustment (isostatic rebound adjustment). E.g. north UK sinks, south rises. OR due to accretion where net deposition in sinks of sediment cells leads to land building up relative to local sea level.

Isostatic rise happens due to subsidence where the weight of deposition of sediment caused crustal sag and delta subsidence e.g. Mississippi River sediment deposition.

Tectonics can cause both Isostatic rise and fall. Folding of sedimentary rock at destructive plate boundaries produce Isostatic rise in land level at anticlines, and Isostatic call in land level at synclines. E.g. Makran coast where Arabian and Eurasian plates collided

2 emergent landforms from sea level change (

Raised beaches (lendalfoot, Scotland).

Fossil cliff (lendalfoot, Scotland)

4 submergant coastal landforms from sea level change (rise)

Ria (Plymouth sound).

Fjärd (gulf of Finland).

Fjord (Milford sound, NZ).

Dalmatian coast (Croatia)

Contemporary sea level change from global warning and tectonic activity statistics

50% 1990-2010 sea level rise is from melted ice sheets.

40% 1990-2010 sea level rise is from thermal expansion.

10% 1990-200 sea level rise is from tectonic activity. But underground volcanic activity can cause thermal expansion.

Geological and marine factors that cause coastal recession (erosion)

Geological= lithology, geological structure.

Marine= long wave fetch, strong longshore drift

2 human actions that influence coastal recession (erossion)

Dredging.

E.g. hallsands 1917. Sea dreaded for sediments to expand Devon port dockyard. Made the sea deeper. So waves had to break onshore and not offshore, so the beach was eroded away to fill the hole. Ale causing 12m wanes and high tide destroyed 29 homes. And lowered beach level by another 2m.

Coastal management.

E.g. Aswan dam on Nile in 1946 reduced sediment volume from 130 million tonnes/yr to 15 million tonnes/yr. erossion rates rose from 20m/yr to 200m/yr as the delta was starved of sediment.

increased flood risk in Bangladesh due to height above sea level (local factor 1/3)

Worlds largest river delta covers most of Bangladesh.

60% is less than 3m above sea level.

A 40cm rise in sea level would submerge 11%, creating 7 million environmental refugees.

increased flood risk in Bangladesh due to subsidence (local factor 1/3)

Caused by deposited then compacted sediment in river delta. HOWEVER isn't a huge issue as its outpaced by fresh deposition causing accretion, cancelling out the subsidence.

Since 1960, 50 islands have subsided by 1.5m, partly dienti human factors of water abstraction reducing groundwater levels, causing land to sing. Especially done in urban areas.

increased flood risk in Bangladesh due to vegetation removal (local factor 1/3)

Salt marshes/ mangrove Forrest’s reduce flood risk. Stabilise sediments to raise land hight. Veg absorb wave energy.

Bangladesh has worlds larg3st mangrove Forrest, but 70% is experiencing veg removal.

Example of a storm surge causing coastal flooding with short term impacts

North Sea flood UK 2013. In December a large storm surge hit the east coast causing widespread flooding.

2 desths. Loss of amenity value with nature reserve damaged in Skegness. All rail services cancelled in Scotland. 1,400 homes flooded.

Economic and social impacts of coastal flooding on developing countries

Bangladesh. River deltas have high agricultural productivity, but saltwater intrusion from floods here damaged rice paddies, leading to job loss and food insecurity.

Philippines typhoon Haiyan 2013 had billions being spent on relief. This increase in public spending diverted funds from potential long term development, towards disaster response.

Bangladesh river deltas are good for trade because of food inland access. But flooding damages ports, disrupting flow of goods

Economic and social impacts of coastal flooding on developed countries

Uk 2014 storms damaged Dawlish warren train line costing the UK economy £1.2 billion through disruption to tourist and fishing industries in the local area.

How coastal flooding causes environmental refugees

Tuvalu is only 4.5m above sea level. 11,200ppl live there. Aus granting visas to 280ppl/yr. Aus giving Tuvalu Aus$16.9 million to expand their landmass off the main island by 6%, and to adapt to climate change.

40cm rise in sea level would submerge 11% Bangladesh, creating 7 million environmental refugees

Groynes purpose, impact in physical processes, and evaluation (hard engineering)

E.g. holderness increased erosion of spurn head.

Purpose= prevent longshore movement of sediment, encourage deposition, build a bigger beach.

Impact on physical processes= deposition and beach accretion, prevention of longshore drift, sediment starvation, increased erosion downdrift.

Evaluate= low cost, improvise tourism, potentially unsightly

Sea wall purpose, impact in physical processes, and evaluation (Hard engineering)

E.g. Dawlish warren 2014 storm surge train line destruction- inefficient.

Purpose= physical barrier against erosion. Flood barriers. Recurved sea walls dissipate, not reflect, wave energy.

Impact on physical processes= destruction of natural cliff face and foreshore environment. If reflective, it can reduce beach volume (cause the erosion it was ment to stop).

Evaluate= expensive, good direct protection against overtopping.

Rip rap (rock armor) purpose, impact in physical processes, and evaluation (Hard engineering)

e.g. coupled with sea wall at Dawlish Warren.

Purpose= break up/ dissipate wave energy. Often used at base of sea wall to protect from undercutting and scour.

Impact on physical processes= reduced wave energy. Sediment deposition between rocks. May become vegetated over time.

Evaluate= may limit beach access. Natural appearance as to concrete structures. Rocks cold dislodge in storms so needs regular monitoring. Relitively expensive.

revetments purpose, impact in physical processes, and evaluation (Hard engineering)

Purpose= absorb wave energy and reduce swash distance by encouraging infiltration. Reduce erosion on dune faces and mud banks.

Impact on physical processes= reduces wave power. Can encourage deposition. May become vegetated. doesn’t stop erosion, just reduces its speed.

Evaluate= shorter lifespan than sea walls, lower cost, better for the environment than sea walls.

offshore breakwater purpose, impact in physical processes, and evaluation (Hard engineering)

e.g. Elmer, UK.

Purpose= forces waves to break offshore, rather than at the coast, reducing eave energy and erosive force.

Impact on physical processes= deposition encouraged between breakwater and beach, can interfere with longshore drift.

Evaluate= maintains beach aesthetics, high investment.

beach nourishment and dune stabilisation evaluate (soft engineering)

ongoing costs are high, dune stabilisation less so

cliff regrading and drainage evaluate (soft engineering)

cliff slope angles reduced to increase stability. Re-vegetated to reduce surface erosion. In-cliff drainage reduces pore-water pressure and mass movement risk. Can be disruptive during construction.

example of sustainable coastal management

it includes= managing natural resources sustainably, creating alternate livelyhoods before existing ones are lost, adaption by relocation, alternate building methods, and educating communities.

It can cause conflict= some loose jobs as natural resources are being used less, relocation may needed where mitigation engineering solutions are too costly/ not technically feasible, engineering schemes cant protect against all threats, and future threats may change therefore creating uncertainty and the need to change plan.

e.g. Maldives. creating artificial islands but he process involves dredging for sand, damaging corals in shallow lagoons where the sand is then added to. Sustainable management of trad income (e.g. fishing) is overlooked in favour of tourism in urban developments. Education of coastal communities on importance of mangrove forests is being done.

Holderness SMP (part of sediment cell 2) management options, players and stakeholders, winners, losers, the future

Management options= Hold the line. holistic approach. Adapting a long term solution. Pursuing adaptive management. Working with natural processes. Providing participatory planning (involving the community in the process).

Players, stakeholders= national gov agencies, local gov, stakeholders in the economy, environment.

Winners= Homewoners, national gov, agencies, stakeholders in economy.

Losers= environmental stakeholders.

the futute= rise in sea level could be 8mm/yr sp the coast may disappear anyway so sea defences wont change the outcome.

Odisha, India SMP problem, management options, stakeholders/ players, winners, losers

Problem= lost 28% of their coastline. Industrialisation, coastal sea bed mining.

Management options= ICZM to manage coast and resources sustainably. Planting mangroves- communities being trained to do so. In Chilka Lake there’s a tourism ban to protect biodiversity and fisheries. morot boat traffic regulated for the wildlife.

Stakeholders/ players= ventral gov e.g. fisheries department. Gov stakeholders in local economy e.g. Odisha Tourism. local fishermen.

Winners= marine life. 400,000ppl benefit from measures improving livelihood of resource-dependent communities.

Loosers= those reliant on industrial activities.

Future= relies on balancing development with conservation. There’s potential for offshore wind, tidal, wave power here.