Coastal Landscapes and Change

1. St. Ninian's (Shetland Islands)

1. Start Bay

1. Dungeness, Kent

1. Within sediment cells there may be negative or positive feedback. An example of negative feedback is where erosion causes rock falls, which then protects the cliff from further erosion
2. TRANSFERS
   1. Longshore drift, wave transport through swash, tides moving sediments in and out, currents and wind
3. SOURCES
   1. Erosion of cliffs, land sediments eroded by rivers, subaerial processes, shells and remains of marine organisms
4. SINKS
   1. Depositional landforms e.g. dunes, marshes and beaches

1. Hydraulic Action: explosion of air cracks rock
2. Abrasion: waves pick up rocks and throw them at the cliff
3. Corrosion: dissolving of certain rocks
4. Attrition: rounding of rocks by collisoin with each other

1. Destructive waves: frequency of 13 to 15 waves per minute, circular motion and a stronger backwash removing sediment from a beach
   1. Atlantic coasts of Norway or Scotland
2. Constructive waves: frequency of 8 or less per minute, elliptical water motion, calmer conditions and a stronger swash leading to deposition and transport of sediment
   1. Mediterranean Sea coasts

1. Wave-cut notch
2. Wave-cut platform
3. Arches, caves, stacks and stumps
4. Geo and blowholes

1. Biological e.g. roots, seaweed acids and boring molluscs
2. Mechanical e.g. freeze-thaw or salt crystallization
3. Chemical e.g. oxidation

1. Rock falls - occur on a steep cliff face when it is weathered, which loosens rocks, and when wave erosion has created a wave-cut notch so that a section of the cliff is no longer supported
   1. Block falls - occur on a slightly shallower gradient but otherwise are similar to rock falls, where wave processes erode the broken blocks, creating a pile of debris at the bottom of the slope
2. Rotational slumping - in inconsolidated muds, sands and clays, mass movement occurs in the form of rotational slumps leaving a crescent-shaped scar above it on the cliff. Vegetation layer usually remains intact on top of each slump
   1. Flow - When there is plentiful water and a higher clay content, mud flows may result, which spill out over the foreshore
   2. Holderness

1. Eustatic: Change in sea level (up or down)
   1. During an ice age, sea levels fall; as the climate warms up, water returns to the sea
2. Isostatic: Change in land level relative to sea level
3. Tectonic: Change shape and size of coasts, can create new coasts
   1. Tectonic plates move and collide, some bits of land are pushed upwards, tsunamis etc.

1. E: Formed by isostatic rebound
   1. Raised beach and fossil cliffs
      1. FC - Near-vertical slope initially formed by marine processes but now some distance inland
      2. RB - Former beach now above the high tide
2. S: Formed by isostatic sinking
   1. Fjard, fjords, rias and Dalmatian coasts
      1. R: A flooded river valley
      2. FJO: Flooded glaciated valley (U-shaped valley)
         1. FJA: Flooded inlet with lower banks than a fjord, formed by post-glacial drowning

1. Physical: Most rapid recession will occur when rocks are weaker, large destructive waves, submergence of the coastline and constant weathering
2. Human: offshore dredging removes sand so waves could keep circular motion leading to a higher impact, coastal defences in one location could increase erosion further down the coast
   1. Inaction? e.g. Do Nothing

1. Wind direction
2. Tides
3. Weather systems

1. Low air pressure over the sea --> water is able to rise upwards --> dome of water forms --> dome of water surges ashore when the low-pressure system moves near a coast --> tropical cyclones together with storm surges can create large storm waves --> massive erosion and sea level rise
   1. CS: Bangladesh and sea-level rise and storm surges

1. Plant succession
   1. Halophytes
   2. Xerophytes
   3. Psammosere
2. Absorb coastal flooding
3. Buffer zones against waves and storms

1. The rocks that make up the base of the land. Igneous (cooled magmas), are more resistant than sedimentary rocks (limestones)

1. Permeability and porosity
2. Weathering

1. To promote the growth of wildlife and create habitats
   1. In a salt marsh (low-energy environment), pioneer plants trap sediment which builds the salt marsh up to a higher level so that other plants can then colonise. In a salt marsh you'd find salt grass and pickleweed
      1. As more and more plants colonise, the amount of fauna increases

1. To act as a physical barrier
   1. Embryo dunes form first and they grow by collecting more sand, trapped by vegetation
      1. Sand dunes are psammoseres that act as a physical barrier. In a sand dune the plants hold the sand together and trap more sand so the dunes can grow. You'd find Marram Grass

1. Dynamic equilibrium - inputs of sediments, weathering on backshore, constructive and destructive waves, offshore currents and longshore drift move sediments
2. Human activities can interfere, e.g. dredging of rivers to make them deeper for ships or building coastal defences

1. Cuspate foreland
2. Haff coastline
   1. Lagoons and mudflats
   2. Baltic Sea
3. Headlands and bays

1. Hog's back cliff
2. Slumped cliff
3. Inactive cliff
4. Tropical cliff with notch

1. Groynes
   1. A: cheapish, maintain the size of a beach, enhanced access to beach
   2. D: £1000 per metre, can be an obstacle, unsightly, can cause narrower beaches
2. Sea wall
3. Revetments
4. Rip-rap
   1. D: even natural rock can contrast with local geology, access difficulties, safety hazard
   2. A: long-lasting, can be placed at susceptible points to protect sea-wall or used as a breakwater groyne
5. Gabions
6. Offshore breakwaters
   1. D: costly between £1m and £2m, looks unsightly at low tide, can increase deposition on the landward side
   2. A: effective at protecting vulnerable sections of the coast, can protect harbour entrances making it safer to enter and leave

1. Beach nourishment
2. Cliff regrading
3. Dune stabilisation
4. Cliff drainage
5. Do Nothing

Anmerkungen:

• More than half of Australia's coast is vulnerable to erosion and retreat due to sea-level rise, especially in the state of Victoria where 80% of the coastline is at risk. What is now considered a yearly flood could become daily by 2100. A 20cm rise in sea level wouldcause US$1.4bn. The environment will suffer as coral reefs will die if they are below 50mdeep. Total costs with a sea level rise of 1.1m in Australia would be AU$226bn.

Anmerkungen:

• Out of all the countries in the 'coral triangle', the Philippines would be worse affected by sea level rise, costing approximately $6.5billion per year. Many of the major cities and towns are built on the coast, leading to exploitation of natural resources and the removal of barriers such as mangrove forests, corals and seagrass.Up to 2.3 million people could be affected by a 1 metre rise.In the city of San Fernando, a 2012 study estimated that by 2100 property losses will be about $2.5 million.