geog coasts

Question 1

whats wave frequency

Answer 1

number of wave crests passing a certain point in a minute.

Question 2

whats wave period

Answer 2

amount of time taken for the wave crest at point A to reach point B

Question 3

whats a sediment cell

Answer 3

a self-contained strech of coast. sediment moves around a cell but not usually from one cell to another. A new sediment cell is usually marked by a barrier such as a change in wind direction or a landform e.g. a headland

Question 4

what do sediment cells help

Answer 4

us to manage coastal defences

Question 5

whats carbonisation

Answer 5

when CO2 in this atmosphere dissolves in rainwater and created carbonic acid that can dissolve rocks e.g. limestone.

Question 6

where is carbonisation increased

Answer 6

in vegetated areas as the porous soils hold high amounts of CO2 due to the decomposing plant debris

Question 7

what is root action

Answer 7

the roots of plants growing into cracks and joints in rocks and exerting pressure that eventually breaks the rocks apart

Question 8

what is burrowing

Answer 8

worms and other vertibrate bringing soil and rock particles to the surface which facilitates for chemical weathering at greater depths

Question 9

what is salt crystalisation

Answer 9

salt-water getting forced into the cracks of rocks, the water being evaporated and leaving the salt behind which applies pressure and eventually breaks the rock

Question 10

what’s freeze thaw

Answer 10

water forced into the cracks of rocks. when it freezes, it expands by 9% which applies pressure to and eventually breaks the rocks.

Question 11

what’s a eustatic change

Answer 11

a global change is sea level due to the exchange of water between the worlds oceans, ice caps and glaciers.

Question 12

what’s a isostatic change

Answer 12

a local change in the level of land due to the earths crust attempting to reach equilibrium. this usually occurs due to the loading/unloading of ice and changes sea levels

Question 13

what’s thermal expansion and how does it increase sea levels

Answer 13

oceans absorbing heat from the atmosphere which causes the water molecules at the surface to expand. the oceans absorb 90% of heat which causes water to expand.

Question 14

how does sea-floor spreading increase sea levels

Answer 14

when magma rises and creates a new ocean floor this pushes water upwards

Question 15

how do earthquakes increase sea levels

Answer 15

can lead to the sudden displacement of the earths crust vertically

Question 16

what is accretion and how does accretion increase sea levels

Answer 16

the creation of new landmasses due to the deposition of sediment. this keeps areas at pace with rising sea levels

Question 17

how does subsidence of ground increase sea levels

Answer 17

soils and land sinking downwards means that sea levels will increase more.

Question 18

how much are sea levels rising in the kiribati and how far is the island away from sea level

Answer 18

1.2cm a year
the island is only 2m above sea level
people are displaces and climate refugees are created

Question 19

what’s happening in jakarta

Answer 19

the capital of indonesia is a megacity with 32mill inhabitiants and people are illegally draining underground aquifers because they don’t have access to public water. this is leading to the ground sinking 25cm a year and is expected to have most of the city underwater by 2050

Question 20

average sea level rise

Answer 20

3-4mm annually

Question 21

what have rates of erosion on the river nile delta increased from and to

Answer 21

25m to over 200m

Question 22

what is a wind wave

Answer 22

a wave generated by immediate local winds that’re not sustaining and will stop when the wind stops

Question 23

what is a swell wave

Answer 23

a self-sustaining wave thats generated by energy below the oceans surface and do not need local winds to be created.

Question 24

why do waves break

Answer 24

they break in shallow water because the crest of the wave begins to move faster than the trough, which experiences friction from sediment and eventually the wave topples forwards

Question 25

what is flocculation

Answer 25

small, fine particles (like clay) are suspended in the water but clump together due to the electrostatic attraction. these form larger particles that sink.

Question 26

what is gravity settling

Answer 26

energy of waves is weaker than the force of gravity, so the waves are forced to drop the sediment they’re holding. the larger particles are dropped first, then the smaller ones

Question 27

what is wave refraction

Answer 27

when waves approach shallow water they slow down due to friction. waves approach the coastline and bend which causes them too loose energy. e.g. waves energy is concentrated on a headland and disperces wave energy into bays.

Question 28

human causes of flooding

Answer 28

• removal of vegetation e.g. mangroves
• over-abstraction of underground aquifers that leads to subsidence of ground
• lack of defences
• climate change
• over-population
• subsidence and the clearing of land
• industrialisation
  engineering projects

Question 29

physical causes of flooding

Answer 29

• topography
• height of land
• storm events and tsunamis