Coastal systems Flashcards

Question

describe rivers as sediment sources

Answer 1

most of the sediment in the coastal zone is a result of an input from rivers, especially in high-rainfall environments where significant rive erosion occurs. sediment may be deposited in estuaries which are brackish (salty) areas where rivers flow into the sea. they are important wildlife habitats. the sediment is then transported throughput the coastal systems by waves, tides and currents

Answer 2

very important areas with unconsolidated (uncompacted ad therefore unstable) cliffs that are erodes easily. in some areas, coastlines can retreat by up to 10m per year, providing a significant sediment input. most erosi9on occurs during the winter months due to more frequent storms.

Answer 3

the wind is a coastal energy source and can cause sand to be blown along or up a beach. sediment transport y winds may occur where there are sand dines or in glacial and desert environments which provide sediment inputs.

Answer 4

in some coastal systems such as Antarctica, Greenland, Alaska and Patagonia, glaciers flow directly into the ocean depositing sediment that was stored in the ice. this occurs when glaciers calve, a process where ice breaks off the glacier

Answer 5

sediment is transferred to the coastal zone when waves, tides ad currents erode offshore sediment sinks such as offshore bars. the sediment is transported onto the beach, helping to build up the beach. storm surges or tsunami may also transfer into sediment into the coastal zone.

Answer 6

sediment is moved along the beach, due to prevailing winds which alter the direction of the waves. this allows sediment to be transported from one section of coastline (as an output) to another stretch of coastline (as an output). this is a very important process. the swash approaches the coast at an angle due to the prevailing winds, transferring sediment along the beach. the backwash pulls the sediment directly back down the beach. the swash then transfers the sediment along the coastline and the process repeats.

Answer 7

sediment budgets are very similar to carbon budgets ad have the same purpose within different systems. they use data of inputs, outputs, stores and transfers to assess the gains and losses of sediment within a sediment cell. in principle a system will operate in a state of dynamic equilibrium where inputs and outputs of sediment are equal. however, human actions and natural variation in the system can disrupt the state of equilibrium.

Answer 8

the littoral zone is the area of land between the cliff's or dunes in the coasts and the offshore area that is beyond the influence of the waves. it is therefore covered by the sea at different points in time.

Answer 9

- short term factors like tides and storm surges - long term factors like changes in sea level and human intervention

Answer 10

the boundary between the sea and the land

Answer 11

the area beyond the influence of waves

Answer 12

the area of land not covered by the sea, but very close to it.

Answer 13

waves which are formed offshore, which are most commonly generated by wind, or less frequently tectonic activity r underwater landslides causing tsunami waves.

Answer 14

- winds move across the surface of the water, causing frictional drag (resistance to the wind by the water) which created small ripples and waves. this leads to a circular orbital motion of water particles in the ocean. - as the seabed becomes shallower towards the coastline, the orbit of the water particles become more elliptical, leading to more horizontal movement of the waves. - the wave height increases, but the wavelength (distance between two waves) and wave velocity both decrease - this causes water to back up from behind the wave until the wave breaks (collapses) and surged up the beach

Answer 15

when the wave moves up the beach

Answer 16

when the waves moves back down the beach into the sea

Answer 17

- strength of the wind - duration of the wind - size of the fetch

Answer 18

wind is essentially air that moves from an area of high pressure to an area of low pressure. the different pressure areas are caused by variations in surface heating by the sun. the larger the difference in pressure between the two areas (pressure gradient) the stronger the winds. as waves are caused by the wind, stringer winds also mean stronger waves.

Answer 19

if the wind is active for long periods of time, then the energy of the waves will build up and increase.

Answer 20

the fetch is the distance over which the wind blows ad the larger it is, the more powerful the waves will be it could also be thought of as the distance to the nearest land mass in particular direction.

Answer 21

constructive waves destructive waves

Answer 22

they tend to deposit material, which creates depositional landforms and increase the size of beaches.

Answer 23

act to remove depositional landforms through erosion, which work to decrease the size of a beach.

Answer 24

formed by weather systems that operate in the open ocean

Answer 25

long wavelength

Answer 26

6-9 per minute

Answer 27

low waves, which surge up the beach

Answer 28

strong swash, weak backwash

Answer 29

localised storm events with stringer winds operating closer to the coast

Answer 30

short wavelength

Answer 31

11-16 per minute

Answer 32

high waves, which plunge onto the beach

Answer 33

weak swash, strong backwash

Answer 34

it causes deposition on the beach, which in turn leads to the beach profile becoming steeper.

Answer 35

steeper beaches favour the formation of destructive waves which are then more likely to occur.

Answer 36

gravity is another key source if energy in coastal environments and is responsible for tides which occur when the gravitational pull of the sun or moon changes the water levels of the seas and oceans.

Answer 37

the difference in height between the tides

Answer 38

channels such as river esturies

Answer 39

when the sun and the moon are in alignment. both of their gravitational forces combine to effectively pull the oceans towards them to cause the highest high tides. on the other side of the planet, this create the lowest possible low tides. this is a spring tide and it creates the largest possible tidal range.

Answer 40

when the sun and the moon are perpendicular to each other. both of their gravitational forces act against each other, so the overall pull is minimised at high tide, but therefore creates a higher low tide. this is a neap tide and it creates the smallest possible tidal range.

Answer 41

tides affect erosion and lead to the formation of different coastal landforms.

Answer 42

rip currents are powerful underwater currents occurring in areas close to the shoreline in some beaches when plunging wave cause a buildup of water at the top of the beach. the backwash is forced under the surface due to resistance from breaking waves, forming an underwater current. this flows away from the shore more quickly due to beach features, such as a gap in a sandbar, creating a rip current.

Answer 43

they occur when the ocean tide pulls water through a small area such as a bay or lagoon.

Answer 44

high-energy coastlines are associated with more powerful waves, so occur in areas where there is a large fetch. they typically have rocky headlands and landforms ad fairly frequent destructive waves. as a result these coastlines are often eroding as the rate of erosion exceeds the rate of deposition.

Answer 45

low energy coastlines have less powerful waves and occur in sheltered areas where constructive waves prevail ad as a result these are often fairly sandy areas. there are landforms of deposition as the rates of deposition exceed the rates of erosion.

Answer 46

wave refraction is the process by which waves turn ad lose energy around a headland on uneven coastlines. the wave energy is focussed on the headlands, creating erosive features in these areas. the energy is dissipated in bays leading to the formation of features associated with lower energy environments such as beaches.