coastal systems

Question 1

what are inputs

Answer 1

sediment can be brought into the system in various ways. energy inputs come from wind, waves, tides and currents.

Question 2

flows

Answer 2

processes such as erosion, transportation and deposition can move sediment within the system.

Question 3

stores

Answer 3

landforms such as beaches, dunes and spits are stores of sediment.

Question 4

what is a negative feedback?

Answer 4

when change in the system causes other changes that have the opposite effect. For examples a beach is eroded the cliffs behind are exposed to erosion, sediment eroded from the cliffs is then deposited on the beach, causing it to grow in size again.

Question 5

positive feedback

Answer 5

when change in the system causes other changes that have a similar effect. e.g. as a beach grows the waves lose energy so deposit more sediment.

Question 6

sources of energy (wind)

Answer 6

-winds are created by moving from areas of high pressure to areas of low pressure.
-strong winds generate powerful waves.

Question 7

sources of energy (waves)

Answer 7

• waves are created by wind blowing over the sea, the friction gives the wave its circular motion.
  -the effect of the wave depends on wind speed and fetch.
  -as the waves break, friction with the sea bed slows the bottom of the waves.

Question 8

sources of energy (tides)

Answer 8

-tides are the periodic rise and fall of ocean surface caused by the gravitational pull of the moon and the sun.
- tides affect the position at which waves break on the beach ( at high tide they break higher up shore.

Question 9

sources of energy (currents)

Answer 9

• a current is the general flow of water in one direction- it can be caused by wind or variations in water temperature and salinity.
  -currents move sediment down the coast (LSD).

Question 10

what are high energy coasts?

Answer 10

they receive inputs of energy in the form of large, powerful waves. these can be caused by strong wind, long fetches and steeply shelving offshore zones high energy coasts tend to have sandy coves and rocky landforms, e.g.cliffs caves stacks and arches.

Question 11

inputs of sediment into the coastal system

Answer 11

-rivers carry eroded sediment into the coastal system from inland.
-From eroded cliffs
-can be formed from the crushed shells of marine organisms
-waves tides and currents can transport sediment into the coastal zones.

Question 12

what is abrasion

Answer 12

rocks smash and grind on the coast, slowly eroding it and smoothing surfaces.

Question 13

what is cavitation

Answer 13

the compressed air expands violently, exerting pressure on the rock and causing pieces to break off.

Question 14

what is wave quarrying?

Answer 14

the energy of a wave as it breaks on a cliff is enough to erode it.

Question 15

solution

Answer 15

soluble rocks such as chalk or limestone can gradually be dissolved by seawater.

Question 16

what is attrition?

Answer 16

bits of rock in the water smash against each other and break into smaller bits.

Question 17

what is solution (transportation)

Answer 17

Substances that can dissolve are carried along in the water.

Question 18

what is suspension (transportation)?

Answer 18

very fine materials such as silt and clay particles, is whipped up by turbulence and carried along in the water.

Question 19

what is saltation (transportation)?

Answer 19

larger particles such as pebbles or gravel, are too heavy to be carried in suspension instead the force of the water bounces them along the surface of the water.

Question 20

when does deposition occur ?

Answer 20

deposition occurs when the load of the sediment exceeds the ability of the wind or waves to carry it.
-friction increases if waves enter shallow water or wind reaches land, this lowers energy.
-flow becomes turbulent and encounters an obstacle.

Question 21

what is salt weathering?

Answer 21

salty water (saline) enters pores or cracks in rocks at high tide. as the tide goes out and the water evaporates, forming salt crystals which exert pressure on the rock- this cause pieces to fall off.

Question 22

freeze thaw weathering

Answer 22

frozen water expands.

Question 23

what is chemical weathering

Answer 23

the breakdown of rock by changing its chemical composition. acidic rain containing carbonic acid .

Question 24

what cause mass movements?

Answer 24

-unconsolidated rocks (clay are prone to collapse as there’s little friction.
-Heavy rain can saturate unconsolidated rock, further reducing friction and making it more likely to collapse.
-runoff can erode fine particles and transport them down slope.

Question 25

how are beaches formed?

Answer 25

when constructive waves deposit sediment on the shore.

Question 26

Barrier islands

Answer 26

they are long narrow islands of sand or gravel that run parallel to the shore ad are detached from it.
- scientists think they are formed after the last ice age, when ice melt caused rapid sea level rise. the rising waters flooded the land behind beaches and transported sediments offshore where it was deposited in shallow water.

Question 27

sand dunes

Answer 27

1. formed when sand deposited by lsd is moved up the beach by the wind.
   2.sand trapped by driftwood forms embryo dunes.
2. over time, the oldest dunes migrate inland as newer embryo dunes are formed- stabilised by vegetation.

Question 28

how are mudflats ad salt marshes formed

Answer 28

-form in sheltered, low-energy environments, e.g. river estuaries or behind spits.
- as silt and mud are deposited by the river or tide, mudflats develop.
-the mudflats are colonised by vegetation that can survive high salt levels.
-deposition continues create an area of salt marsh.

Question 29

eustatic sea level change

Answer 29

caused by a change in the volume of water in the sea, or by a change in the shape of the ocean basins.
-tectonic movements e.g. sea floor spreading
-changes in climate as ice sheets melt and water expands .

Question 30

isostatic sea level change

Answer 30

-uplift or depression of the earth’s crust due to the accumulation or melting of ice sheets.

-subsidence of land due to shrinkage after abstraction of groundwater.

-tectonic plates where one is forced under the other.

Question 31

sea level change over the last 10,00 years

Answer 31

• at the last glacial maximum, sea level was 130m lower than present.
  -as temps started to increase, ice sheets melted and sea level rose rapidly. it reached its present level around 4000 years ago.
  -since 1930 the sea level has been rising.

Question 32

climate change causes change in sea level

Answer 32

-increase in temperature are likely to increase sea level through the melting of ice sheets and thermal expansion of water in oceans.
-global sea level rising by 2mm a year.

Question 33

impacts on coasts

Answer 33

-storms will be more frequent and intense.
-more frequent and severe coastal flooding.
-submergence of low-lying islands, approximately 70% of the Maldives will be submerged if global sea level rises by 0.5m.
-contamination of water sources and farmland.

Question 34

sea level fall results in coastlines of emergence

Answer 34

when sea level falls relative to the coast, new coastline emerges from the sea. This creates different land forms.
-raised beaches
- exposes wave cut platforms.

Question 35

sea level rise results in coastlines of submergence

Answer 35

rias - a drowned river valley.

fjords- drowned glacial valley’s

Dalmatian coastlines- the valley behind is submerged leaving behind raised land .

Question 36

what are the four coastal management attitudes?

Answer 36

-hold the line (upkeep of defences)
- advance the line (additional and upkeep of defences.
-do nothing.
-managed retreat.

Question 37

breakwaters

Answer 37

concrete blocks depositedmoff the coast. they force waves to break offshore. The waves energy and erosive power are reduced.

expensive and can be damaged in storms

Question 38

sea wall and revetment disadvantage

Answer 38

creates strong swash which erodes under the wall. and are very expensive to build and maintain.

Question 39

what is beach nourishment ?

Answer 39

the application of sediment to beaches from elsewhere.

Question 40

beach stabilisation

Answer 40

reducing the slope angle and planting vegetation

Question 41

dune regeneration

Answer 41

dunes are restored by nourishment or stabilisation and act as a barrier absorbing wave energy.

Question 42

shoreline management

Answer 42

the coast is split into cells, for each cell a plan of the four attitudes is devised with the aim of protecting important sites without causing problems elsewhere in the sediment cell.

Question 43

what is integrated coastal zone management

Answer 43

it aims to protect the coastline in a relatively natural state whilst allowing people to use and develop it in different ways:
-the environment is viewed as a whole.
-different uses are considered e.g. fishing, industry, tourism.
- it is a dynamic strategy.