Water- EQ1 Flashcards

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1
Q

why is the hydrological cycle a closed system

A

there is a transfer of energy not matter between the systems and its surroundings
- no external inputs or outputs

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2
Q

what is a flux

A
  • amount of matter transferred from one store to another e.g. throughflow or surface runoff
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3
Q

what is the hydrological cycle powered by

A

solar energy (causes changes in the state of water)
gravitational potential energy (exerts a pull on water)

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4
Q

what are the largest and smallest stores

A

largest - ocean (1335040 x 10^3 km^3) 96.9% of all water
smallest - atmosphere ( Atmosphere 12.7 x 10^3 km^3)

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5
Q

what are the largest and smallest fluxes

A

largest- ocean evaporation (413 x 10^3 km^3)
smallest - ocean to land water vapour transport (40 x 10^3 km^3)

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6
Q

what stores have the biggest and smallest residency times

A

Biggest- Cryosphere - RT= 15,000 years
Smallest - biosphere ( 7 days ) or atmosphere ( 10 days )

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7
Q

what stores are considered unrenewable and why

A

Fossil water - water stored underground in rocks a long time ago when climate was much wetter so cant be replenished
Cryosphere - Ablation (glacial melt ) due to climate change reduces storage capacity of water as ice as its not currently being replaced

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8
Q

what is the global water budget

A

the annual balance between the fluxes and size of water stores

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9
Q

what does the global water budget generally look like

A
  • water generally considered renewable source because there is constant circulation and replenishment without any losses from the planet
  • the availability of water may vary throughout the year tho
    e.g. in summer when plant absorption and transpiration and evaporation rates are higher
  • soil moisture will also vary - important for plant growth , runoff and throughflow fluxes
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10
Q

what is orographic rainfall

A
  • relief rainfall
  • caused when humid air is forced to rise over mountains
  • when the air cool at higher altitude, moisture condenses forms clouds and droplets of water which fall due to gravity
  • the windward side experiences the rain and the leeward side is drier (rain shadow)
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11
Q

what is frontal rainfall

A
  • caused when warm air is forced to rise at a warm or cold front, usually as a part of a low pressure system (depression) CCC
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12
Q

what is convectional rain

A
  • caused when ground and lower atmosphere are heated by the suns energy causing rising thermals of air ; humidity in the air condensed when it cools at higher altitudes
  • forms large cumulonimbus clouds , often followed by intense heavy rainfall
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13
Q

what is interception

A

when vegetation intercepts precipitation before it hits the grounds
plants also absorb water through their roots

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14
Q

what is infiltration

A

movement of water downwards through the spaces in the soil - continues until capacity is reached and the soil is saturated

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15
Q

what is throughflow

A

movement of water downslope through the soil towards a base level (river lake or sea)

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16
Q

what is surface run off

A

rain falling onto the ground may flow over the surface when the rain is so intense there is no time to infiltrate

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17
Q

what is saturated overland flow

A
  • if all soil spaces are full of water then any further rain cannot infiltrate and so will run off the surface
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18
Q

what is percolation

A
  • movement of water downwards through porous or permeable rocks
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19
Q

what is groundwater flow

A
  • downward and sideways movement of water in rock layers under the influence of gravity and rock structure
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20
Q

what is evaporation

A
  • change in state of water from liquid to gas when heated by the sun
    increases with temp wind and dark surfaces
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21
Q

what is transpiration

A

plants absorb water from the soil through their roots to use within the process of photosynthesis , they then transpire water to the surface of their leaves to be evaporated (EVT)
increases with tree cover leaf growth and soil moisture

22
Q

what is channel flow

A
  • runoff moves to the lowest points in a landscape where it collects to form a linear body of water flowing over the ground
    increases with amount of rain or snow melt
23
Q

how does climate influence the hydrological cycle

A

affects amount of precipitation and seasonal patterns
more direct runoff when precipitation is greater or more intense
evaporation and transpiration greater when hotter

24
Q

how does vegetation type and amount affect the hydrological cycle

A
  • high transpiration rates increase local rainfall
  • large forests intercept a lot of rain , slowing infiltration runoff and throughflow
  • extensive tree cover will increase evt and reduce channel flow
25
Q

how does soil depth and structure affect the hydrological cycle

A
  • soil with more space allow more water to infiltrate reducing overland flow and increasing throughflow
  • clay soils reduce infiltration and so increase evt from the ground and runoff
26
Q

how does slope angle altitude and shape affect the hydrological cycle

A
  • orographic rainfall will be created by high ground
  • steeper slopes cause reduced infiltration more runoff and faster throughflow
  • slopes direct water into channels (increased channel flow)
27
Q

how does deforestation affect the hydrological cycle

A
  • removal of tree cover reduces interception and evt, increasing runoff , soil erosion and flooding during intense rainfall events
  • reduced evt may cause local droughts as rainfall reduces ( amazon basin)
28
Q

how does land use change affect the hydrological cycle

A
  • changing catchment areas from natural vegetation to urbanised impermeable surfaces increases runoff and channel flow , creating higher discharges and more flooding
  • agriculture - logging and overgrazing - cattle disrupt structure of the soil and reduce infiltration rates
29
Q

how does reservoir creation affect the hydrological cycle

A

damming a river prevents channel flow , reducing discharges downstream and creating an evaporation source

30
Q

how does abstracting water affect the hydrological cycle

A
  • when taken faster from the ground than it can be replaced
31
Q

what is the water budget equation

A

P = Q + E +- S
P = precipitation
Q= channel discharge
E= EVT
S= change in storage

32
Q

what is a water budget

A

balance between inputs and outputs

33
Q

why is soil moisture important

A
  • important for successful plant growth
  • important in an ecosystem so that plants support other trophic levels
  • for farmers important so that they have enough soil moisture to produce high yield crops
34
Q

what is a river regime

A

A river regime is the annual variation in the discharge or flow of a river at a particular point, and is usually measured in cumecs

35
Q

what is a river regime influenced by

A
  • the size of the river and where discharge measurements are taken along its course
  • the amount, seasonality and intensity of the precipitation
  • the temperatures, with possible meltwater and high rates of evaporation in the summer
  • the geology and soils particularly their permeability and porosity; groundwater noted in permeable rocks is gradually released into the river as base flow
  • the type of vegetation cover: wetlands can hold water and release it slowly into the river
  • human activities aimed at regulating a river’s discharge
36
Q

what is storm hydrograph

A

storm hydrographs show discharge changes over a short period of time, often no more than a few days.

37
Q

what are the main features of a storm hydrograph

A
  • rising limb
  • peak discharge
  • lag time ( time interval between peak rainfall and peak discharge
  • falling limb
  • base flow ( day to day discharge level)
38
Q

why is urbanisation the main factor that creates a flashy hydrograph

A
  • Construction work leads to the removal of the vegetation cover. This exposes the soil and increases vegetation cover
  • Bare soil is eventually replaced by a covering of concrete and tarmac, both of which are impermeable and increase surface runoff.
  • The high density of buildings means that rain falls on roofs and is then swiftly fed into drains by gutters and pipes.
  • Drains and sewers reduce the distance and time rainwater travels before reaching a stream or river channel.
  • Urban rivers are often channelised with embankments to guard against flooding. When floods occur, they can be more devastating.
  • Bridges can restrain the discharge of floodwaters and act as local dams, thus prompting upstream floods.
39
Q

what does a flashy hydrograph look like

A
  • Short lag time, high peak, steep rising limb
40
Q

what does a flat hydrograph look like

A
  • Long lag time, low peak, gently sloping rising limb
41
Q

what factors affect the outcome of a hydrograph

A
  • weather/climate
  • rock type
  • soils
  • relief
  • basin size
  • shape of basin
  • antecedent conditions
  • vegetation
  • human activity
42
Q

what is blue water

A
  • visible part of the hydrological cycle ( rivers streams lakes groundwater
43
Q

what is green water

A

the invisible part of the hydrological cycle - stored in soil and vegetation

44
Q

what is residence time

A
  • the average time a water molecule will spend in a reservoir or store
45
Q

what is the drainage basin cycle

A

a subsystem within the global hydrological cycle
- an open system

46
Q

what is the catchment

A
  • area of land drained by a river and its tributaries
47
Q

what is the watershed

A

the highland that divides and separates waters flowing to different rivers

48
Q

what is needed for precipitation to form

A
  • air cooled to saturation point
  • condensation nuclei like dust to facilitate the growth of droplets in clouds
  • a temp below dew point
49
Q

what are thw six key influencing factors on a drainage basin system

A
  • amount of precip
    -type of precip (e.g. snow acts a temporary store and large fluxes of water released when thawed)
  • seasonality
  • intensity of precip (difficult to infilatrate if very intense )
  • variability ( secular (long term) periodic ( shorter term) stochastic (random factors e.g. storm)
  • distribution of rain in the basin
50
Q

what is a human impact of precipitation

A

cloud seeding - introduction of silver iodide pellets to act as condensation nuclei and attract water droplets ( aim to increase rain in drought stricken areas)

51
Q

human impact on infiltration and soil water

A
  • land use
  • grasslands less favourable for infiltration than forests ( reduced interception and increased soil compaction and more overland flow)
  • overgrazing compacts
  • ploughing loosens ( increases infiltration by aerating soil)
52
Q

what is the human impact on groundwater

A
  • extensive use for irrigation led to decreasing water tables
  • e.g. aral sea - began shrinking in 1960s and by 1994 fallen by 16m
  • in british cities less groundwater in being used in industry - levels are rising leading to flooding of cellars and basementsi n houses and leakage into london underground - water uspplies also more likely to become polluted