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OCR Earth's Life Support Systems A-Level Geography > 1a) > Flashcards

1a) Flashcards

1
Q

What is a drainage basin?

A

An area of land that is drained by a river and its tributaries.

It can vary a lot in size right from small local basins to major river systems, e.g. Mississippi, Nile and Amazon

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2
Q

What is a confluence?

A

Occurs where two or more flowing bodies of water joined together to form a single channel.

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3
Q

What is a drainage divide?

A

The line that separates neighbouring drainage basins (aka watershed).

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4
Q

What is the mouth?

A

The place where a river enters a lake larger river or Ocean.

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5
Q

What is the source?

A

The place where a river begins (aka spring).

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6
Q

What is a tributary?

A

A small river or stream that joins a larger river.

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7
Q

What is a delta?

A

Wetlands that form as Rivers empty their water and sediment into another body of water i.e. ocean Lake or another river.

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8
Q

What is the main input in the hydrological cycle?

A

Precipitation (the falling of moisture from the clouds).

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9
Q

List the processes of the hydrological cycle -

A
  • Condensation
  • Evaporation
  • Evapotranspiration
  • Steam flow
  • Surface runoff
  • Percolation
  • Infiltration
  • Interception
  • Groundwater flow
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10
Q

List some examples of storage in the hydrological cycle -

A

(Land, Atmosphere, and Oceans).

  • Clouds
  • Leaves
  • Ice
  • Snow
  • Oceans
  • Rivers
  • Aquifers
  • Lakes / reservoirs
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11
Q

List outputs of the hydrological cycle -

A
  • Human uses
  • Evapotranspiration
  • Evaporation
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12
Q

How much water does the water cycle circulate per year as inputs and outputs between stores?

A

505,000 km^3

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13
Q

Define evapotranspiration

A

The combined losses of transpiration and evaporation

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14
Q

Define surface runoff

A

The horizontal movement of water over the land surface

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15
Q

Define interception

A

The precipitation that is collected and stored by vegetation

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16
Q

Define throughflow

A

The movement of water horizontally within the soil

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17
Q

Define infiltration

A

Water that seeps down into the soil

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18
Q

Define percolation

A

Water that seeps deep into the underlying bedrock

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19
Q

Define groundwater flow

A

Deep movement of water horizontally through the Rock / the movement of water within aquifers

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20
Q

Define ablation

A

The loss of ice and snow, especially from a glacier through melting, evaporation and sublimation

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21
Q

Define discharge

A

The volume of water passing in measuring point in a given time within a river

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22
Q

What is the dew point?

A

The dew point is the critical temperature at which air becomes saturated and can hold no more vapour, and thus condensation occurs

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23
Q

What is a catchment?

A

The same thing as a drainage basin

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24
Q

What happens to precipitation after it falls?

A
  • Most quickly flows into streams and Rivers
  • In higher lattitudes and mountainous drainage basins precipitation often falls as snow and may remain on the ground for several months; meaning a considerable time lag between snowfall and runoff
  • High intensity precipitation (e.g. 10 to 15 mm per hour) move rapidly overland into Streams and Rivers
  • prolonged precipitation link to depressions and frontal systems and may cause river flooding
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25
Q

Define transpiration

A

The diffusion of water vapour to the atmosphere from the leaf pores (stomata) of plants

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26
Q

What factors affect transpiration and how? (Short term/ Diurnal changes)

A
  • temperature🌡️- during the daytime when temperatures are higher transpiration occurs at a greater rate
  • wind 🌬️ - wind removes the boundary layer of water vapour hugging the leaf surface
  • water availability 💦 - plants are adapted to reduce moisture loss and so if a plant has less water it is less likely to transpire
27
Q

What are the main three types of clouds?

A

Cumuliform
Stratiform
Cirrus

28
Q

Describe cumuliform clouds:

A

Flat bases and considerable vertical development

Mostly form when air is heated locally to contact with Earth surface

This causes heated air particles to rise through the atmosphere, expand due to the fall in pressure with altitude and cool; and thus condense and form clouds

29
Q

Describe stratiform/layer clouds:

A
  • Develop when an air mass moves horizontally across the surface; often the ocean
  • this process together with some mixing and turbulence is known as advection;

(the horizontal movement of an air mass which often results in either heating or cooling)

30
Q

Describe cirrus clouds:

A

Form at a high altitude

Look wispy and consists of tiny ice crystals

They do not produce precipitation and therefore have little influence on the water cycle

31
Q

Define adiabatic expansion:

A

The expansion of a parcel of air due to a decrease in pressure.

Expansion causes cooling

32
Q

What is a lapse rate?

A

It describe the temperature changes that occur within an air parcel as it rises vertically away from the ground.

33
Q

Clouds form when water vapour is cooled to it’s dew point; how does this cooling occur?

A
  • Adiabatic expansion
  • advection
  • Air masses rise as the crossing mountains barrier or else turbulence forces their ascent
  • a relatively warm air mass mixes with a colour one
34
Q

What are the three types of lapse rate?

A
  • Environmental lapse rate (ELR)
  • Dry adiabatic lapse rate (DALR)
  • Saturated adiabatic lapse rate (SALR)
35
Q

What is the elr?

A

The decrease in temperature usually expected with an increase in height to the troposphere.

On average the temperature falls by 6.5 degrees C for every km of height gained.

36
Q

What is the DALR?

A

The rate at which a parcel of dry air ( i.e. less than 100% humidity so that condensation is not taking place) cools.

Calling caused by any act expansion is approximately 10 degrees C/ km.

37
Q

What is SALR?

A

The rate at which a saturated parcel of air ( i.e. one in which condensation is occurring) cools as it rises into the atmosphere

The rate of cooling a slower about 7 degrees C because condensation releases latent heat.

38
Q

What is the troposphere?

A

The lowest portion of the atmosphere and where all the weather takes place.

75% of atmospheric mass and 99% of water vapour and aerosols.

39
Q

What factors influence the storm hydrograph?

A
  • Size of drainage basin
  • Shape of drainage basin

DR VILTUSP

  • Deforestation
  • Relief
  • Vegetation
  • Intensity of precipitation
  • Length of precipitation event
  • Type of precipitation
  • Urbanisation
  • Soil Texture and structure
  • Permeability of rock type
40
Q

How does Deforestation affect hydrograph?

A

Lag time is faster and and peak is higher in a deforested catchment.

Less interception and evapotranspiration and more surface runoff in a deforested catchment.

41
Q

How does relief affect hydrograph?

A

Lag time is shorter and peak is higher in a steeper basin.

Water reaches channel more rapidly in a steeper basin as water is travelling more quickly downhill.

42
Q

How does vegetation affect hydrograph?

A

Lag time is slower and peak lower in a forested basin.

Vegetation intercepts a large portion of rainfall. Where trees are deciduous, discharge is higher in a forested basin in winter as there is less interception.

43
Q

How does intensity of precipitation affect hydrograph?

A

Lag time is shorter and peak is higher after intense rainfall.

Where rain is falling faster than the infiltration rate there is infiltration-excess overland flow. This is common after a summer storm.

44
Q

How does length of precipitation event affect hydrograph?

A

Lag time is shorter and peak is higher after prolonged event.

Ground is saturated with water so there is more saturation-excess overland flow.

45
Q

How does type of precipitation affect hydrograph?

A

Lag time is slower and peak is lower after snowfall.

Snow does not reach channel but is stored on ground surface. As snow melts, the meltwater will reach the channel quickly as infiltration is impeded if the ground is still frozen.

46
Q

How does Urbanisation affect hydrograph?

A

Lag time is faster and peak discharge is higher in an urbanised catchment.

Surface runoff is higher in urban areas because there are more urban surfaces (concrete and tarmac) and sewers take water rapidly to rivers.

47
Q

How does soil Texture and structure affect hydrograph?

A

Lag time is slower and peak is lower in areas of sandy soil.

Sandy soils have large pore spaces than clay soils. Infiltration is most rapid in sandy soils.

48
Q

How does Permeability of rock type affect hydrograph?

A

Lag time is shorter and peak is higher in an area of impermeable rock type.

Impermeable rocks are saturated more quickly than porous and pervious rocks. Saturation-excess overland flow is more common.

49
Q

How does rock type affect Ribble catchment discharge patterns?

A

Millstone grit (impermeable) - densely packed sand particles with very few pore spaces - overland flow is rapid.

Carboniferous Limestone - joints and bedding planes widened by weathering, throughflow reaches river channel quickly.

50
Q

How does soil type affect River Ribble catchment discharge patterns?

A

Peat Soil - major store of groundwater - can slow down the increase in discharge.

51
Q

How does Shape/size of Ribble Catchment affect discharge patterns?

A

Elongated basin - one of largest in NW England - increased lag time

52
Q

What are the two theories of precipitation?

A

Bergeron-Findeisen and Collision theory.

53
Q

Explain the Bergeron-Findeisen theory-

A
  • Mixed phase (solid, liquid and gas) clouds where temperatures are below 0 degrees C –> equilibrium vapour pressure over liquid is greater than over ice
  • This means that the ice crystals ❄️ gain water vapour ♨️ at the expense of liquid water droplets 💦 (as pressure gradients move substances from high to low pressure)
  • If there are relatively few ice crystals present then that allows these ice crystals to become large enough for precipitation
  • If these droplets pass through the air warmer than 0 degrees Celsius as they fall and they will arrive at the ground as rain
54
Q

Explain the collision theory-

A

Warm clouds; large cloud droplets fall at a higher terminal velocity than smaller cloud droplets.

Large droplets collide with smaller dropped it’s too far even larger drops.

When drops become large enough that the downwards velocity (relative to the surrounding air) is greater than the upwards velocity of surrounding air (relative to the earth) -
then drops can fall as precipitation.

55
Q

How does rainfall affect Ribble catchment discharge patterns?

A

Varies from 1775 mm riversource 890mm at the estuary.

Evenly distributed throughout the year.

Infiltration-excess overland flow is most common after intense summer thunderstorms.

Saturation excess overland flow is more common in late winter although the peat can store large quantities of water.

56
Q

How does urbanisation affect Ribble catchment discharge patterns?

A

Major tributary; River Calder flows through heavily urbanized areas such as Burnley.

Discharge is rapid because water is directed into River by storm drains and runoff from concrete and tar surfaces.

However the Calder does not contribute much to flooding in the Ribble because its basin is circular.

57
Q

How does agriculture affect Ribble catchment discharge patterns?

A

Some farming practices in the Forest of Bowland (the basin of the tributary River hodder) contribute to flooding in the lower Ribble.

Over stocking with sheep (often on steep and marginal land) has led to the degradation of vegetation cover.

Soil has been exposed to erosion leading to gullying and faster overland flow.

Heather burning for grouse shooting is not always properly managed. On some moors the peat cover has been lost and surface runoff is encouraged.

58
Q

Define abstraction

A

The extraction of water from a natural source.

59
Q

Define aquiclude/ aquifuge-

A

Rock that doesn’t hold water; i.e. is impermeable such as clay.

60
Q

Define water table

A

The upper surface of the zone of saturation.

This varies seasonally.

61
Q

Define the phreatic zone-

A

The area beneath the water table with rocks are permanently saturated.

62
Q

Define the aeration/ vadose zone-

A

The zone nearest / around the water table which is seasonally wetted and dried as the water table moves.

63
Q

Define the aeration/ vadose zone-

A

The zone nearest / around the water table which is seasonally wetted and dried as the water table moves.

64
Q

Explain the glacial system

A

Dunno lol.

OCR Earth's Life Support Systems A-Level Geography (3 decks)

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