Coasts

Question 1

What is the case study for coasts

Answer 1

The Holderness coast

Question 2

What is a sediment cell

Answer 2

areas along the coastline where the movement of sediment is largely self contained. considered a closed coastal sub system. sediment is largely recycled within them rather than having significant inputs and outputs. the boundaries tend to be headlands and peninsulas which act as a natural barrier

Question 3

Describe the coast as a system

Answer 3

it is an open system in dynamic equilibrium. if the equilibrium is disrupted due to landslides storms or human activity the change can either be reversed through negative feedback or enhanced through positive feedback.

Question 4

How does wind energy determine the effects of other processes

Answer 4

Wind creates waves due to frictional drag leads to erosion
Length of the fetch determines the size and energy of waves - how much wind its exposed to.
Prevailing wind direction determines other processes such as longshore drift
erosion- wind picks up sediment and uses it to erode other materials through erosion

Question 5

What is the energy of a wave dependent on

Answer 5

the strength of the wind the duration and the length of the fetch

Question 6

what are the key features of waves

Answer 6

height- the difference between the crest and the trough
length- the distance between crests
frequency - the time lapse between crests

Question 7

how does a wave break

Answer 7

wave approaches shallower water so friction with the seabed increases and the bottom of the wave slows down. this increases the height and steepness of the wave until it the upper part plunges and breaks onto the shore.

Question 8

what is swash and backwash

Answer 8

swash is the rush of water up the beach and the backwash is the water being dragged back down the beach

Question 9

what are the two types of waves

Answer 9

constructive and destructive

Question 10

describe destructive waves

Answer 10

high wave height (steep) high frequency 10-14 per minute. powerful backwash and little swash. very little material moved up the beach but lots pulled away. the force of each wave may project some shingle towards the back of the beach forming a large ridge known as a storm beach.

Question 11

describe constructive waves

Answer 11

low wave height with a long wavelength between crests. 6-8 per minute. weak backwash due to the swash quickly losing volume and energy as it percolates into the sand. material slowly and constantly moved up the beach to form berms (ridges)

Question 12

how is the beach profile a negative feedback system

Answer 12

the steep beach profile of a destructive wave is slowly flattened as the constructive waves drag the sediment back down the beach. eventually the beach angle is reduced so much that the waves become constructive. equally constructive waves push sediemtn up the beach increasing beach angle and encouraging more destructive waves to break. negative feedback maintains the state of dynamic equilibrium

Question 13

what is wave refraction

Answer 13

waves drag in the shallow water approaching the headland, the waves become high and steep and short. the part of the wave in deeper water moves faster so the wave bends. the low energy wave spills into the bays (causing deposition) as most of the energy concentrated onto the headland causing erosion

Question 14

what are the three types of currents

Answer 14

longshore currents - most waves do not hit the coast head on but approach at an angle. this generates a flow of water (current) parallel to shoreline - transports sediment longshore drift
rip current - strong currents moving away from the shoreline due to a build up of seawater from incoming waves. run parallel then out through a breaker zone. hazardous to swimmers
Upwelling- the global pattern of currents circulating in the oceans can cause deep cold water to move towards the surface displacing warmer surface water. results in a cold current rich in nutrients

Question 15

what are the parts of a coastal zone

top 4

Answer 15

backshore- area between high water mark and end of the swash zone. only influenced by storm activity
foreshore-between hwm and lwm most important zone for marine processes in times not influenced by storm processes
inshore- area between lwm and end of breaker zone waves cease to have an impact on the land beneath them
offshore- area beyond breaker zone activity is limited to deposition of sediments

Question 16

what are the parts of the coastal zone bottom 4

Answer 16

nearshore zone- area extending seaward from the hwm to the area where waves begin to break and includes;
swash zone- area where a turbulent layer of water washes up the beach following the breaking of a wave
surf zone - area between where the waves break and the swash zone
breaker zone - area where waves approaching the coastline begin to break around depth of 10-5m

Question 17

compare high and low energy coasts

Answer 17

high: predominantly strong wave power, high waves, strong prevailing winds, long length of fetch, erosion greater than deposition. landforms include wave cut platforms headlands and cliffs. e.g Flamborough head

low energy coasts: low wave energy, waves spread out energy is dissipated, low waves, deposition greater than erosion, tidal range. features include beaches and spits e.g spurn head