Water EQ1 Flashcards

1
Q

What is a store?

A

A store is an areas where water is held e.g. oceans.

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2
Q

What is a a fluxe?

A

The rate if flow between different stores.

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3
Q

What is a a process?

A

The physical mechanisms which drive the fluxes of water between stores.

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4
Q

Why is the global hydrological systems classes as a ‘closed’ system?

A

It is a closed system as there are no external input and outputs meaning the total volume of water is constant and finite.

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5
Q

What is a the global hydrological system?

A

The circulation of water around the earth.

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6
Q

What drives the global hydrological system?

A

The power threat fives the global hydrological system comes from two sources
- solar energy (in the form of heat)
- gravitational potential energy (causing rivers and water to flow down hill and precipitation to fall to the ground)

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7
Q

Why are the main types of stores and there percentage contribution?

A

Oceans - 97%
Cryosphere - 1.9%
Ground water - 1.1%
Rivers and lakes - 0.01%
Soil moisture - 0.01% (biosphere)
Atmospheric moisture - 0.001%

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8
Q

What is blue water?

A

Water stirred in rivers, streams, lakes and groundwater in liquid form (visible part of hydrological cycle)

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9
Q

What is green water?

A

Water stores in the soil and vegetation (invisible part of hydrological cycle)

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10
Q

What are the major fluxes in the hydrological system?

A

Precipitation > movement of water in any form from the atmosphere to the the ground
Evaporation > the change in state of water from liquid to gas

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11
Q

What is fossils water?

A

Ancient, deep groundwater from formed pluvial(wetter) periods which has a very long residency time and not renewable.

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12
Q

What’s is the residency time for each of the stores?

A

Oceans - 3,600 years
Icecaps - 15,000 years
Groundwater - 100/200 up to 10,000 years
Rivers and lakes - 2 weeks to 10 years
Soil moisture - 2 to 50 weeks
Atmospheric moisture - 10 days

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13
Q

What is transpiration?

A

The diffusion of water from vegetation into the atmosphere, involving a change from gas to liquid.

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14
Q

What is the global water budget?

A

The global wage budget takes into account all the water that is held in stores and flows of the global hydrological cycle annually (the amount of water available)
E.g. only 2.5% of total water on earth is fresh water and most of it is inaccessible for human use.

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15
Q

What is a residence time?

A

The average time a molecule of water will spend in a store.

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16
Q

Which water stores are non- renewable?

A
  • Fossils water
  • The cryosphere losses
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17
Q

Why is most of earths water unavailable for human usages?

A
  • only 2.5% of global water is freshwater
  • 69% do the available fresh water is locked up in ice caps ect which is found at high latitudes and high altitude conditions making is inaccessible
  • 30 % of fresh water is found in groundwater, where some of its very deep (fossil water) and therefor also inaccessible
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18
Q

What is the drainage basin?

A

The drainage basin is a sub system within the global hydrological cycle. It is the area of land drained by a river and its tributaries.
It is an open system as it has external inputs and outputs that varies the amount of water in the basin over time.

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19
Q

What is the watershed?

A

The boundary of a drainage basin, it divides and separates waters flowing to different rivers.

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20
Q

What are the main input into a hydrological system?

A

The main input into the hydrological cycle is predication which can varies in type and amount.

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21
Q

What is needed for predication to fall?

A
  • air cooled to saturation point
  • a condensation nuclei to facilitate the growth of droplets in clouds
  • a temperature below dew point
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22
Q

How does precipitation vary in the drainage basin hydrological cycle?

A
  • amount of precipitation (impacts drainage discharge and fluxes)
  • type of precipitation (snow can act as a temporary store and large fluxes of water can be released at once when melted and entry into the drainage system fast or delayed)
  • seasonality (monsoons)
  • intensity of precipitation (ground water flow and infiltration effected, flooding risk p)
  • variability (secular (long term), periodic (annually/seasonally) and stochastic (random, thunderstorms)
  • distribution of precipitation (in large drainage basins tributaries can start in different climate zones)
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23
Q

What is convectional rainfall and is it formed?

A

Happens in hot climates and tropical areas where
1. The earths hot surface heats the air above it
2. The heated air rises, expands and cools at the dew point. Condensation takes place.
3. Further ascent causes more expansion and rain takes place.

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24
Q

What is orographic rainfall and how does it take place?

A

When air is forced to rise over a barrier (mountains), it cooled and condenses at the dew point forming rain on the wind ward slopes. A rain shadow takes place where the leeward slope receives little rainfall.

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25
Q

What is frontal rainfall and how does it form?

A

This is where warm air (lighter and less dense) is forced to rise over cold denser air. As it rises the air reaches the dew point and it’s ability to hold water vapour is decreased and condensation occurs.

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26
Q

What are the main flows in a drainage basin?

A
  • interception (retention of water by plants and soils)
  • infiltration ( water travels vertically into soil)
  • percolation (vertical movement of water through permeable rocks)
  • through flow (lateral movement of water downslope through soil)
  • groundwater (transfer of percolated water though rock laterally)
  • surface runoff (water on the surface of the ground)
  • river and channel flows
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27
Q

What is interception and what are the three main components?

A

Interception is the process by which water is stored in the vegetation. It three main components are
- interception loss
- through fall
- stem flow

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28
Q

What is interception loss?

A

This is when water is retained by plant surfaces and later either absorbed or evaporated off.

29
Q

What is throughfall?

A

This is when rainfall persist or is relatively intense and water drops from the leaves and twigs of vegetation.

30
Q

What is stem flow?

A

This is when water trickles along twigs and branches and then down the trunk or stem of vegetation.

31
Q

What impacts the amount of interception?

A
  • type of vegetation (coniferous or deciduous trees)
  • Season (less leaves on trees in winter)
  • amount of vegetation (higher density means higher interception)
  • wind speeds (dislodge water and reduce evaporation)
  • intensify and duration of rainfall (saturation levels of trees)
32
Q

What is infiltration?

A

The vertical movement of water from the ground surface into the soil.

33
Q

What is infiltration capacity?

A

The maximum rate at which rain can be absorbed by a soil.

34
Q

What impact the rate if infiltration?

A
  • level of saturation of the soil (antecedent soil moisture)
  • soil texture (sand, silt have different permeability)
  • type and amount of vegetation
  • slope angle (steep slopes encourage surface runoff.
  • duration of rainfall
35
Q

What are the main outputs of a drainage basin hydrological cycle?

A

Evaporation > when moisture is lost directly into the atmosphere from liquid to gas
Transpiration > the biological process by which water is lost from plant through pores.
River discharge > flow of water into another drainage basin, lake or sea

36
Q

What is evapotranspiration?

A

The combined effect of evaporation and transpiration

37
Q

What is potential evapotranspiration?

A

The water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation.

38
Q

What are the main physical factors that influence the drainage basin cycle?

A
  • climate
  • soils
  • geology
  • relief
  • vegetation
39
Q

How does climate affect the drainage basin cycle?

A

Climate has a role in influencing the type and amount of precipitation overall and the amount of evaporation. Also impacts vegetation type.

40
Q

How does soils influence the drainage basin cycle?

A

Soils impact the type of flux by determining the amount of infiltration and through flow and the type of vegetation

41
Q

How does geology influence the drainage basin cycle?

A

Geology impacts the subsurface processes such as percolation and groundwater flow and indirectly soil formation.

42
Q

How does relief influence the drainage basin cycle?

A

Largely affect the different flows within the system, it impacts the amount of precipitation and the amount of surface runoff.

43
Q

How does vegetation influence the drainage basin cycle?

A

Largely affect the different flows as the presence or absence of vegetation has major impacts on interception loss, infiltration, surface runoff and transpiration.

44
Q

What are the main human factors that influence the drainage basin cycle?

A
  • deforestation
  • changing land use
  • creating new water storages
  • extracting water
45
Q

What are the main human factors that influence the drainage basin cycle?

A
  • deforestation
  • changing land use
  • creating new water storages
  • extracting water
  • river management
46
Q

How does humans impact precipitation levels?

A

Human activity can affect precipitation by cloud seeding. Silver iodide pellets or ammonium nitrate act as condensation nuclei to attracted water droplets increasing rainfall.

47
Q

How is the drainage basin system effected by deforestation?

A

Clearance of tree and vegetation reduces the amount of transpiration and increases infiltration and surface runoff. Subsequently increasing flood risk.

48
Q

How is the drainage basin system effect by changes in land use for agriculture?

A
  • increase in livestock farming increase the amount of soil being compresses decreasing infiltration and increasing surface runoff (linked to deforestation)
  • ploughing ground increases infiltration by loosening soil
  • contour ploughing decreases surface runoff reducing flood risk
49
Q

How is the drainage basin influenced by changing land use via urbanisation?

A
  • The rapid increase in urban surfaces such as concrete and tarmac increase surface runoff by reducing infiltration/percolation.
  • drainage systems also deliver rainfall more quickly to streams and rivers increasing flood risk
50
Q

Human impacts of the hydrological system is the Amazon?

A

The sheer scale of deforestation (20% of the forest destroyed) has disturbed the drainage basin by
- reduced precipitation levels (leading to further rainforest degradation)
- more surface runoff and infiltration
- more evaporation and less transpiration
- more soil erosion and silt (nutrients) being fed into rivers

51
Q

How has a river management influenced the hydrological system?

A
  • construction of storage reservoirs holds back river flow
  • abstraction of water for human usages reduces river flow
  • abstraction of groundwater for irrigation lowers water table
52
Q

What is a water budget?

A

It is the annual balance between precipitation, evapotranspiration and runoff. Overall it’s the annual balance between the inputs and outputs.

53
Q

How is a water budget calculated?

A

P = E + R / S
P = precipitation
E = evapotranspiration
R = runoff
S = change in storage over a period of time

54
Q

Why are water budgets useful?

A
  • Water budgets at a country or regional level provide a more useful indication of availability of water supplies
  • locally it shows how the balance between inputs and outputs effect soil moisture availability (important for agriculture)
55
Q

Why is available soil moisture important to calculate?

A

Available soil moisture is the amount of water that can be stored in the soil and is available for growing crops. It very valuable for farmers to who can use it to identify when irrigation may be required and how much (reducing water waste)

56
Q

What is a river regime?

A

The annual variations in discharge or flow of a river at a particular point, and is usually measured in cumecs.

57
Q

How is the characteristics of a river regime affected?

A
  • size of the river and where discharge measurements is taken along its course
  • amount, seasonality and intensity of precipitation
  • temperature (melt water and evaporation)
  • geology (permeability and porosity)
  • vegetation cover
  • human activities that regulate river discharge (damn building)
58
Q

What are the examples of different river regimes?

A
  • Yukon
  • Amazon
  • Indus
59
Q

What is a storm hydrograph?

A

They show the variations of discharge within a short period of time normally a storm or a group of storms usually shows only a few days.

60
Q

What are the main features of a storm hydrograph?

A

Rising limb > as the rainfall starts and discharge
Peak discharge > reached sometime after peak rainfall.
Lag time > the time interval between peak rainfall and peak discharge
Falling limb > once precipitation labels decrease the discharge also decreases
Base flow > when discharge returns to normal leaks

61
Q

What physical features determine the shape of a storm hydrograph?

A
  • size of drainage basin
  • shape of drainage basin
  • drainage density
  • rock type
  • soil
  • relief
  • vegetation
62
Q

What human factors determine the shape of a storm hydrograph?

A
  • urbanisation
  • land use
63
Q

How does urbanisation impact the shape of a storm hydrograph?

A
  • construction (urban sprawl) leads to the removal of vegetation and soil replaces by impermeable surfaces increasing surface runoff
  • high building density means more interception by roofing that fall into drainage systems
  • drains and sewage reduce the time for water reaching stream or rivers
  • river management may be used to decrease chances of flooding (embankments)
    This all results in an increased flood risk and a flashy response to intense rainfall.
64
Q

What is the characteristics of a ‘flashy’ response hydrograph?

A
  • short lag time
  • high peak discharge
  • steep rising limb
65
Q

What causes a flashy response?

A
  • intense precipitation exceeding soil capacity / rapid snow melt
  • impermeable rock increasing surface runoff
  • high steep slopes encouraging surface runoff
  • small basins
  • circular basin due to shorter lag time
  • low amount of vegetation
  • antecedent conditions
  • urbanisation/deforestation/down slope ploughing
66
Q

What are the characteristics of a attenuated response hydrograph?

A
  • long lag time
  • low peak discharge
  • gentle rising limb
67
Q

What causes an attenuated response?

A
  • steady rainfall/high evaporation rates
  • permeable rock (limestone)
  • low gentle slopes
  • larger basins
  • dense vegetation
  • reforestation/contour ploughing
68
Q

What are the role of planners in managing land use in a drainage basin?

A

Environmental mangers and local governments look at the catchment of a drainage basin upstream and downstream in order to manage the impacts of urbanisation and changes in land use which have exacerbated flood risk
- flood defences
- afforestation