Water Cycle Flashcards
(85 cards)
1
Q
What is a system approach
A
These approaches study the hydrological phenomena by looking at the balance of inputs and outputs, and how water is moved by stores and flows
2
Q
What is a store
A
Reservoirs where water is held, such as the oceans, lakes
3
Q
What are fluxes
A
The rate of flow between the stores
4
Q
What are processes
A
The physical mechanisms that drive the fluxes of water between the stores
5
Q
What is the cryosphere
A
Areas of the earth where water is frozen into snow or ice
6
Q
What is blue water
A
Water is stored in rivers, lakes and groundwater in liquid form
7
Q
What is green water
A
Water stored in the soil and vegetation
8
Q
What is precipitation
A
The movement of water in any form from the atmosphere to the ground
9
Q
What is evaporation
A
The change in state of water from a liquid to a gas
10
Q
What is residence time
A
The average time a water molecule will spend in a reservoir or store
11
Q
What is fossil water
A
Ancient, deep groundwater from former pluvial (wetter) periods
12
Q
What is transpiration
A
The diffusion of water from vegetation into the atmosphere, involving a change from a gas to a liquid
13
Q
What is what is groundwater flow
A
The slow transfer of percolated water underground through pervious or porous rocks
14
Q
what are examples of fluxes (5)
A
- ocean precipitation
- ocean evaporation
- ocean to land water vapour
- land precipitation
- evaporation, transpiration
15
Q
what are the examples of stores (6 )
A
- Ice
- ocean
- groundwater
- land
- permafrost
- vegetation
16
Q
what are the 3 components of the hydrological cycle
A
- stores: are places where water is held eg the ocean
- fluxes: this is the measurement of the rate of flow between the stores
- processes: the physical factors which drive the fluxes of water between stores
17
Q
the hydrological cycle is what system (o/c)
and driven by…
A
closed system
driven by solar energy + gravitational potential energy
18
Q
what is a closed system
A
occurs when there is a transfer of enery but not matter between the system and the surroundings (inputs come from within the system)
19
Q
what is an open system
A
receives inputs from and transfers outputs of energy and matter to other systems
20
Q
how does solar energy impact the hydrological cycle
A
heated by the sun, water on earth’s surface evaporates into the atmosphere also from the soil by plants from leaves by transpiration
21
Q
how does gravitational energy impact the hydrological cycle
A
water moves through the system by plant interception or over land as surface runoff
22
Q
what is the global water budget
A
- also known as balance
- annual balance of water fluxes and the size of the water stores
23
Q
what affects the balance
A
surface run off makes up the difference to make it balanced
24
Q
where is most of the water stored on earth
A
in the ocean
25
what is residence times
* the average time a water molecule will spend in the reservoir or store
26
what does the cryosphere include
* cryosphere includes: any eater that is frozen, ice caps, continental ice sheets, glaciers, ice bergs, permafrost
27
how does the cryosphere affect the global water budget
as the greater it is the less water fluxes but the greater the water stores
28
what would happen to the cryosphere in the future due to human impact
it would decrease due to global warming so the ice would melt
29
what is the drainage basin cycle and what is it often referred to
* is a subsystem within the global hydrological cycle.
* as the catchment (the area of land drained by a river and its tributaries)
30
what are the factors of the drainage basin cycle (o/c)
an open system with external inputs and outputs that cause the amount of water in the basin to vary over time
31
what is a watershed
The boundary (usually high land) that separates one drainage basin from another.
32
what is a source
The beginning or starting point of a river, often in upland areas.
33
what is a tributary
A smaller stream or river that flows into a larger one.
34
what is a confluence
The point at which two rivers or streams meet.
35
what is the mouth
The point where the river meets the sea, lake, or another river.
36
how does the drainage basin work as a system 3 ways:
1. theres precipitation- can get intercepted by vegetation-surface storage-infiltration-soil moisture-percolation- groundwater- groundwater flow- then ends up in the river channel
2. precipitation- then intercepted- can then evaporate or transpiration
3. precipitation- interception- surface runoff or overland flow- which can then be evaporated or go to the river channel
37
what factors affect inputs of a drainage basin
precipitation to form requires:
* air cooled to saturation point with relative humidity of 100%
* condensation nuclei, such as dust particles, to facilitate the growth of droplets in the clouds
* a temperature below dew point
38
what are the impacts of precipitation on the drainage basin
1. rainfall amount
2. type of precipitation
3. seasonality
4. intensity if precipitation
5. variability of rainfall
6. distribution of precipitation within a basin
39
how does rainfall amount impact the drainage basin
have direct impact on drainage discharge
40
how does type of precipitation impact the drainage basin
eg formation of snow, can act as a temporary store and large fluxes of water can be released into the system after a period of rapid melting resulting from thaw
41
how does seasonality impact the drainage basin
in some climates such as monsoon, mediterranean or continental seasonal patterns of rainfall or snowfall can have a major impact on the physical processes within the drainage basin
42
how does intensity of precipitation impact the drainage basin
major impact on flows on or below the surface. It is difficult for rainfall to infiltrate if rain is intense as soil is saturated and has no capacity
43
how does variability of rainfall impact the drainage basin
1. long term eg result of climate change trends
2. periodic variability happens in an annual, seasonailty or daily basis
3. stochastic (random) variability results from random factors eg localised thunderstorms
44
how does distribution of precipitation within a basin impact the drainage basin
is more noticeable in large river basins eg Rhone or Nile which have tributaries that start in different climatic zones
45
what are the types of rainfall (3)
1. convectional
2. cyclonic
3. drographic
46
what is the convectional rainfall
when land becomes hot, the air above expands and rise. As it does it cools and condenses. If it continues to rise rain will fall
47
what is the cyclonic rainfall
warm air, lighter + less dense, is forced to rise over cold, denser air. It cools and condenses as it rises forming rain
48
what is the drographic rainfall
when air is forced to rise over a barrier, such as a mountain, it cools and condenses forming rain
49
what is interception
is when water is stored (temporarily) in the vegetation
50
what are the 3 ways intercepted water becomes a flow
interception loss, throughfall, stem flow
51
When is interception the greatest and why can it vary
What can it be impacted by
Greatest at the start of a storm
Varies depending on the type of tree eg dense needles of a co iferoud tree allows greater accumulation of water
Meteorological conditions- wind speeds can decrease interception loss as amount of rainfall decreases, relative importance of interception loss will decrease
52
What is infiltration
The process by which water soaks into (or absorbed by) the soil
53
What is infiltration capacity
Is the maximum rate at which rain can be absorbed by the soil in a ‘given condition’ and is expressed by mm/hr
54
What does the rate of infiltration depend on (6)
1. Duration of rainfall
2. Antecedent soil moisture
3. Soil porosity
4. Vegetation cover
5. Rain drop size
6. Slope angle
55
What are the drainage basin system outputs (4)
1. Evaporation
2. Transpiration- depends on the time of yr and type of vegetation cover
3. Evapotranspiration (EVT)- combined effect of evaporation and transpiration
4. Potential Evapotranspiration (PEVT)
56
What is potential Evapotranspiration
Water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation
57
What is overland flow
* Surface run off due to rapidity of reaching the channel
* Primary agent of soil erosion as sediment is removed by a range of erosive processes
58
What is through flow
Very slow transfer of percolated water through pervious or porous rocks
59
What is percolation
Continuum of the infiltration process
It is the deep transfer of water into permeable rocks (with joints or pores)
60
What is saturated overland flow
* Much slower transfer process as it results from the upward movement of the water table in the evaporation zone.
* after succession of winter storms the water table rises to the surface at the base of hillsides. Leads to saturated overland flow making a major contribution to channel flow
61
What is groundwater flow
Transfer of water down slope through the soil via natural pipes and percolates.
Fast in porous sandy soils
62
What is channel flow
Occur in river once water from the 3 transfer processes reaches it
63
what is rain shadow
a dry area on the leeward side of a mountainous area (away from the wind).
The mountains block the passage of rain-producing weather systems and case a "shadow" of dryness behind them
64
what are the physical factors that affect the drainage basin cycle (5)
1. climate
2. soil
3. geology
4. relief
5. vegetation
65
how does climate affect the drainage basin cycle
has a role in influencing the type and amount of prcipitation overall + amount of evaporation + also impact the vegetation type
66
how does soil affect the drainage basin cycle (3)
determines the amount of infiltration + throughfall + indirectly the type of vegetation
67
how does geology affect the drainage basin cycle
can impact on the subsurface processes such as percolation and groundwater flow land (therefore on aquifers). Indiretly is can alter soil formation- how permeable a rock is lets more or less water through
68
how does relief affect the drainage basin cycle
can impact on the amount of precipitation. Slopes can affect the amount of runoff
69
how does vegetation affect the drainage basin cycle
the presence or absence of this can have a major impact on the amount of interception, infiltration and occurance of overland flow, as well as transpiration rates
70
what are 7 human factors that affect the drainage basin cycle + hydrological cycle
1. deforestation
2. irrigation
3. urbanisation
4. Mining
5. Dam building
6. Ground water abstraction
7. Cloud seeding
71
how does deforestation affect the drainage basin cycle + hydrological cycle
cutting down trees increases run-off, decreases evapo-transpiration (and therefore cloud formation) and leads to more extreme river flows as water is not intercepted + stored by the trees
72
how does irrigation affect the drainage basin cycle + hydrological cycle
taking water from a river or underground store can reduce river flow, lower water tables and increases evaporation by placing water in surface stores (ditches/canals) or by crops removing water from the cycle as they grow
73
how does urbanisation affect the drainage basin cycle + hydrological cycle
EG
* removal of of vegetation and replacement with impermeable surfaces and drains can speed up overland flow and evaporation and can lead to higher river levels.
* it also decreases the amount of water which returns to groundwater storage, possibly reducing water table
* eg increased flooding in manchester 2015
74
how does mining affect the drainage basin cycle + hydrological cycle
* breaking up of rocks leads to increased silting up of lakes, rivers and reservoirs leading to reduced storage capacity in these areas.
* Mining may also lead to reduced vegetation cover leading to increased run-off, lower evapo-transpiration and cloud formation altering the rainfall pattern
75
how does dam building affect the drainage basin cycle + hydrological cycle
and an EG
* greatly reduces the discharge of a river as storage is increased. Leads to increased evaporation and therefore can alter rainfall patterns
* EG- Lake Nassar behind the Aswan Dam in Egypt is estimated to have evaporation losses of 10-16 billion cubic metres every year.
* represents loss of 20-30% of egyptian water volume from the River Nile
76
how does ground water abstraction affect the drainage basin cycle + hydrological cycle
and EG
* in some places water is taken from aquifers at a rate higher than the replacement level.
* This causes reduced groundwater flow and a lower water table. increased industry or deforestation also increases groundwater storage , increasing the risk of flooding if the table water reaches the surface
* EG china groundwater irrigates 40% of farmland and provides 70% of drinking water in the north west and North.
* Groundwater droppped a metre per year between 1974-2000
77
how does cloud seeding affect the drainage basin cycle + hydrological cycle
and EG
* the attempt to change the amount or type of precipitation by dispersing substances into the air that serve as cloud condensation nuclei (hygroscopic nuclei)
* new technology and research claims to have produced reliable results that make cloud seeding a dependable and affordable water-supply practice for many regionsbut effectiveness still debatable
* EG China used it in Beijing before the 2008 Olympic games to create rain to clear the air of pollution
78
why do people value cloud seeding (3)
* to increase how drops combine and it only enhances the rain from previous clouds it doesnt make clouds
* is used for hydroelectric power as organisations want more snow in winter so there is more surface run off in spring.
* to protect wine grapes from damaging hale as disperses the clouds and increases rainfall during dry periods
79
what are percolines
lines of concentrated water flow between soil horizons to the river channel
80
what is albedo
a measure of the proportion of the incoming solar radiation that is reflected by the surface back into the atmosphere
81
what is the water budget
* the annual balance between inputs (precipitation) and outputs (evaporation and channel flow)
82
what is a positive and negative water balance
* a positive water balance - where there is a surplus of water precipitation > EVT
* or a negative water balance- there is a deficit of water
EVT > precipitation
83
what is the water balance equation
P = Q+ E+- S
P= precipitation
Q= discharge
E= evaporation
S= changes in the store
84
what is the water balance at
1. the equator
2. 30° N/S (deserts)
3. at 40-60° N/S equator
1. positive balance as lots of precipitation due to heat rising forming clouds = rain
2. negative water balance as the air cools and sinks there so less clouds= less rain
3. 3. positive water balance (eg UK) as hot air rise again = clouds
85
what is a river regimes
* the annual variation in discharge or flow of a river at a particular point or gauging station usually measured in cumes (cubic metres/second)
* much of this flow is not immediate precipitation or run-off, but is supplied from groundwater etween periods of rain
