Key Knowledge (water) Flashcards
1
Q
system
A
a set of interrelated components working towards some kind of process
2
Q
flow/transfer
A
a form of linkage between one store/component and another that involves movement of energy or mass
3
Q
store/component
A
a part of the system where energy/mass is stored or transformed
4
Q
input
A
the addition of matter and/or energy into a system
5
Q
how might a pond work as a system
A
- inputs: precipitation, leaf fall during autumn, seeds carried by winds and birds
- flows/transfers: photosynthesis, infiltration, transpiration
- stores: water, soil, plants
- outputs: water infiltrating into the soil below, evaporation, seed dispersal
6
Q
types of systems
A
- closed: energy is transferred into and out of the system. all matter is enclosed e.g. the global water and carbon cycle [sediment cell]
- open: matter and energy can be transferred from the system into the surrounding environment e.g. the drainage basin (water) or a woodland (carbon) [coastal system]
7
Q
feedback types
A
- dynamic equilibrium
- positive feedback
- negative feedback
8
Q
dynamic equilibrium
A
the balanced state of a system. when opposing forces, or inputs and the equilibrium is equal
9
Q
positive feedback
A
occurs where the effects of an action are amplified by changes to the inputs/outputs
10
Q
negative feedback
A
occurs where the effects of an action are nullified by changes to the inputs/outputs/processes
11
Q
sea ice melting positive feedback example
A
- temperature increase (change)
- sea ice cover melts and shrinks
- ocean water absorb more solar radiation than highly reflective sea ice
- temperature warms
- sea ice cover melts and shrinks
- temperatures warm
12
Q
surface temperatures decreasing negative feedback example
A
- surface temperature decreases slightly
- decrease the earths albedo
- decreased evaporation from the oceans
- fewer low clouds in the atmosphere
- surface temperature increase slightly
- increases in the earths albedo
- increased evaporation from the oceans
- more low clouds in the atmosphere
13
Q
phases of change
A
- sublimation (solid->gas)
- deposition (gas->solid)
- condensation (gas->liquid)
- evaporation (liquid->gas)
- melting (solid->liquid)
- freezing (liquid->gas)
14
Q
fusion
A
where a solid becomes a liquid and vice versa
15
Q
vaporisation
A
when a solid becomes a gas and vice versa
16
Q
breaking bonds
A
because of this strong bond a lot of energy is required for a phase change (fusion, vaporisation and especially sublimation)
17
Q
latent heat
A
- as water molecules become heated by the sun they become agitated and begin to try to break the bonds between them
- however there is not enough heat in the sun to do this
- the water molecules absorb energy from their surroundings to give them the final energy that they need to break the bonds between them
- this energy is called latent heat
- as latent heat is taken from the surroundings it cools down the surroundings (why air remains cool)
18
Q
condensation
A
- latent heat is released by the water molecules as they slow down and join together
- so: evaporation could be thought of as a cooling process
- meaning condensation
19
Q
salinity
A
salt content
20
Q
the hydrosphere - where is water
A
- only 2.5% of global water is fresh water, with 1.2% of that being surface fresh water
- groundwater is very important (London’s natter is 70% groundwater) but the ground could sink -> if you extract too much salt water may contaminate
21
Q
the hydrosphere - the 4 locations of global water v
A
- atmospheric water (water vapour with some liquid water (cloud/rain droplets)
- cryospheric (ice)
- oceanic (oceans but not inland seas)
- terrestrial (groundwater, soil, moisture, lakes, wetlands and rivers)
22
Q
oceanic water
A
- average depth of 3682m
- covers 72% earths surface
- only 5% explore
23
Q
cryospheric water
A
- large parts of arctic ocean is sea ice
- does not raise sea levels when ice melts
24
Q
ice shelf (cryosphere)
A
large area of ice on sea, ice sheets and glaciers move out to sea
25
ice sheet (cryosphere)
glacial land ice covering more than 50,000km squared
26
ice cap (cryosphere)
glacial land ice covering less than 50,000 km squared (still big)
27
glaciers (cryosphere)
rivers of ice melting across land (usually found in deep mountain valleys)
28
permafrost (cryosphere)
land that remains frozen(top layer may melt in summer - active zone)
29
formation of clouds
- Clouds form when air becomes saturated, or filled, with water vapor. Warm air can hold more water vapor than cold air, so lowering the temperature of an air mass is like squeezing a sponge. Clouds are the visible result of that squeeze of cooler, moist air. Moist air becomes cloudy with only slight cooling.
- global atmospheric circulation is the main factor that determines cloud formation and rainfall
30
terrestrial water
- surface water (river ponds and lakes)
- rivers (stores/transfers)
- lake (if bigger than 2 hectares)
- wetlands (main ecosystem of the arctic)
- groundwater (water underground on spaces of rock)
- soil water (water held along with air in unsaturated layers of soil)
- biological water (water stored in biomass)
- biomass (all living and formerly living material)
31
atmospheric water
- equivalent to entire surface of planet covered in 25mm water (average of 12,900km cubed)
- 0.04% of worlds freshwater - 0.001% of worlds water
- amount atmosphere can hold doubles with 10 degrees Celsius rise (water exists in all 3 states in atmosphere)
32
precipitation
rain, snow, hail and sleet
32
interception
when water is caught by trees and plants
33
infiltration
when water enters the ground
34
stem flow
water lands on plants and runs down their stems
35
overland flow
anywhere water flows over the land surface
36
through flow
when water flows through the ground (through soil layer) (relatively slow)
37
transpiration
where water vapour comes out of the leaves
38
evapotranspiraation
water rises as vapour from the ground or released from leaves
39
ground water
water deep in the ground
40
soil water
water held deep in the ground
41
ground water flow
the slow movement of ground water (slowest)
42
percolation
movement of water down through the ground
43
surface storage
lakes, ponds and puddles
44
ground water storage
water stored underground in bedrock
45
the drainage basin
the area of land surrounding a river, from which the river receives water and subsequently drains this water
46
confluence
occurs when two or more flowing bodies of water join together to form a single channel
47
tributaries
a freshwater stream that feeds into a larger stream or river
48
what processes have immediate flows of water
- precipitation
- evaporation
- transpiration
49
what processes have flows of water that takes hours
- interception
- infiltration
- surface runoff
- stemflow
- chanel flow
- river runoff
50
what processes have flows of water which takes days
- surface storage
- percolation
- vegetation storage
- channel storage
- through flow
- soil water storage
51
what processes have flows of water which takes months/years
- vegetation storage
- soil water storage
- ground water storage
- groundwater flow
52
factors changing flow rates
- impermeable surfaces have been built not allowing for infiltration
- agricultural machinery has compressed soils (reduces amount of soil water storage) so soils saturated faster and less infiltration so more overland flow
- impermeable bedrock prevents percolation
- slowest way: throughflow and groundwater flow -> infiltrates soil and percolates to saturated groundwater stores below
- interception
53
water balance
within a drainage basin the balance between inputs, outputs is known as the water balance/budget
54
water balance equation
- P = Q+E +/- change in storage
- (precipitation = runoff+evapotranspiration +/- change in storage)
55
key stats
- % of water in oceans = 96.5%
- largest freshwater stores (sizes) = glaciers/ice sheets (30 cubic metres of ice)
- slowest flows = groundwater flow (30cm/decade)
- longest stores = ground water storage (million)
- interception by rainforest = 66%
- interception by grass = 30-60%
56
water surplus
precipitation (ppn) exceeds evapotranspiration -> above field capacity
57
soil moisture utilisation
evapotranspiration (ET) > ppn
- plants + humans have to utilise water from the soil -> plants use capillary water because soil is not saturated
58
soil moisture recharge
when ppn>ET again so soil moisture is being replenished until field capacity
59
soil moisture deficiency/water deficit
- when all soil moisture is used up
- plants wilt and many die
- no available water in soil at all
60
field capacity
is the maximum amount of water an area can hold
61
river regime
the variability in river discharge throughout the course of the year
62
discharge
the amount of water passing through a river each second measured in cumecs (Metres cubed per second)
63
discharge equation
discharge = cross section area of water (m squared) x speed (m/s) = cumecs (metres cubed per seconds)
64
reasons discharge changes over time and distance
- human intervention -> dams, roads, drainage/sewage
- gradient (topography)
- water from tributaries
- season -> increased/decreased precipitation at different times of the year
- erosion rates
65
storm hydrographs
a type of graph that shows the changes in river discharge in the lead up to and following the start of a storm
66
rising limb
increasing discharge as storm water enters the river channel
67
lag time
time precipitation takes to return to river
68
falling limb
fall in discharge back to base level
69
base flow
starting + finishing flow of river
70
peak rainfall
where precipitation is at its highest
71
peak discharge
discharge at its highest (higher river runoff)
72
storm runoff
extra water above base flow, a rainfall event causes
73
extremes of hydrographs
- lag time differences -> flashy would suggest really high peak discharge with a short lag time meaning it id hard to prepare for
- subdued: very slow to respond, discharge does increase however not massively, have a large lag time so easier to prepare for
74
may experience flooding if these characteristics are present
- steep land
- impermeable bedrock
- urban area
- single valley
- no vegetation
75
physical factors affecting the shape of the hydrograph
- drainage basin shape
- slope angles
- drainage density
- antecedent (prior) rainfall
- rock type
- vegetation cover
- amount and intensity of precipitation
- drainage basin size
76
drainage basin shape (physical factors affecting the shape of the hydrograph)
narrower basin = less time water has to travel therefore a faster flow
77
slope angles (physical factors affecting the shape of the hydrograph)
a steep sided drainage basin; water gets to the river more quickly than in areas of gentle slopes (topography)
78
drainage density (physical factors affecting the shape of the hydrograph)
high drainage density (lot of surface streams acting as tributaries to main river) have flashy hydrographs -> all water arrives at the measuring station at the same time
79
antecedent (prior) rainfall (physical factors affecting the shape of the hydrograph)
if already saturated then overland flow increases because infiltration capacity has been reached. as overland flow is faster -> lag time is reduced
80
rock type (physical factors affecting the shape of the hydrograph)
if rock type is impermeable (shale rocks) overland flow will be higher. throughflow and infiltration will be reduced, meaning a flashy hydrograph -> if it was a rock like sandstone, hydrograph would be subdued
81
vegetation cover (physical factors affecting the shape of the hydrograph)
thick vegetation = much interception, holding water on its leaves slowing the movement of rainwater to the ground so to river channels -> water also lost due to evaporation and transpiration -> this subdues storm hydrographs
82
amount and intensity of precipitation (physical factors affecting the shape of the hydrograph)
heavy storms with a lot of water entering the drainage basin over a short time result in higher discharge -> lag time likely to be greater in basin if precipitation is snow rather than rain
82
drainage basin size (physical factors affecting the shape of the hydrograph)
large drainage basins catch more precipitation and so have a higher peak discharge compared to smaller basins. smaller basins tend to have shorter lag times (precipitation does not have as far to travel)
83
human factors affecting the shape of the hydrograph
- deforestation
- afforestation
- agriculture
- growth of urban areas
- soft engineering flood management
- water abstraction
84
deforestation (human factors affecting the shape of the hydrograph)
reduces interception rates allowing rainwater to hit the surface directly, infiltration increase = rapid overland flow + flashy hydrographs -> increased peak discharge and shorter lag times
85
afforestation (human factors affecting the shape of the hydrograph)
opposite effect
-> decreased peak discharge
-> decreased lag time
(both due to increased interception subdues hydrographs)
86
agriculture (human factors affecting the shape of the hydrograph)
ploughing land breaks up soil allowing greater infiltration, subduing graphs (also terracing on hillsides stops movement of water)
87
growth of urban areas (human factors affecting the shape of the hydrograph)
urban areas leads to flashy hydrographs due to construction of infrastructure + impermeable surfaces (tarmac + concrete) (shorter lag time + high discharge)
88
soft engineering flood management(human factors affecting the shape of the hydrograph)
Attempt to reduce flashiness in a river hydrograph -> afforestation
89
water abstraction (human factors affecting the shape of the hydrograph)
Reduces base flow and so more water must reach the channel before it reaches bank full capacity -> lower levels of saturation
90
Physical factors changing the water cycle
- drought
- desertification
- rock type
- slope angles
- intensity/amount of precipitation
- energy of environment
- presence of vegetation
91
Human factors changing the water cycle
- urbanisation
-deforestation
- agriculture
- water abstraction
- irrigation methods
