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Water Cycle Content Flashcards

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1
Q

What is the global hydrological system?

A

It is a closed system
long term
driven by solar energy and gravitational potential energy
no new water can enter system and no water can be lost
so generally considered a renewable resource (except for fossil water i.e aquifers)

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2
Q

What is the global water budget?

A

annual balance of water fluxes

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3
Q

What are the 4 main water stores?

A

Atmosphere, hydrosphere, biosphere and lithosphere

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4
Q

What percentage of water is stored where?

A

97.5% in oceans (as saltwater)
only 2.5% is freshwater
of which:
69% is in cryosphere
30% groundwater
1% is accessible surface water

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5
Q

What are drainage basins?

A

local hydrological cycle
defined as an area of water drained by a river and its tributaries with a watershed as its boundary
open subsystem
linked to other drainage systems by inputs and outputs

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6
Q

What are the inputs to the Drainage Basin?

A

Precipitation
Volume and condition of precipitation affected by:
seasonality
Latitude (e.g ITCZ)

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7
Q

What is convectional rainfall?

A

daily
1. morning heat warms low level moisture
2. moisture evaporates and rises
3. as it rises it cools condense and forms clouds
4. rainfall occurs
in tropical climates convectional rainfall is most common

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8
Q

What is frontal/cyclonic rainfall?

A

two air masses meet a depression forms
warm moist air forced to rise above cold air mass
water moisture cools and condenses
form cyclonic precipitation
(approx. 100 depressions in UK each yr)

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9
Q

What is relief/orographic rainfall?

A

warm moist air meets land of high relief
forced to rise above the hill to continue
as it rises cools, condenses and forms cloud
so forms rainfall

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10
Q

What are fluxes of drainage basin?

A

-interception
-infiltration
-surface runoff
-throughflow
-percolation
-groundwater flow

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11
Q

What are the differences between flows and fluxes?

A

-flows are transfers of water in the hydrological cycle
-fluxes describe the rate of flow between the major global stores e.g. land and ocean

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12
Q

What is interception?

A

vegetation interferes with precipitation fall

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13
Q

What is infiltration?

A

movement of water from surface into the soil

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14
Q

What is surface runoff?

A

water flows overland

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15
Q

What is throughflow?

A

water moves through the soil

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16
Q

What is percolation?

A

water moves from the soil into porous rock (bedrock and aquifers)

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17
Q

What is groundwater flow?

A

gradual transfer of water through porous rock

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18
Q

What are the outputs of the drainage basin? What are rates affected by?

A

Evapotranspiration:
Evaporation= loss of water from the surface of a body of water to the atmosphere. Rates influenced by:
- volume of body of water: Larger SA= <evaporation
- vegetation cover: more= >evaporation
- colour of surface beneath water: black tarmac<evaporation

Transpiration= water is lost to the atmosphere through stomata in plants

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19
Q

What is the water table?

A

upper level at which pore spaces and fractures in the ground become saturated

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20
Q

What physical factors affect the drainage basin?

A

-Climate= influences rainfall and vegetation
-Soil composition= influences infiltration and throughflow
-Geology= influences percolation and groundwater flow
-Relief= influences surface runoff
-Vegetation= influences interception, overland flow and evapotranspiration
-Size= influences precipitation storage amount

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21
Q

What anthropogenic factors affect the drainage basin?

A

-Cloud seedling= this is where substances are dispersed into the air to provide something for condensation to occur on
-Deforestation= less vegetation so less interception and infiltration and consequently increased surface runoff= more flooding
-Afforestation= more vegetation so more interception and infiltration so less runoff= more evapotranspiration
-Dam construction= reduce downstream river flow and discharge, increase surface stores= more evaporation
-Change in land use= infiltration 5x faster in fo
-Ground water abstraction=rest than grassland so converting to farmland= increased soil compaction and more surface runoff
-Irrigation= drop in water tables due to high water usage
-Urbanisation= impermeable surfaces reduce infiltration, increase surface runoff= river discharge increases

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22
Q

What is the equation for calculating water budget?

A

Precipitation= Discharge + Evaporation +- changes in stores

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23
Q

what is potential evapotranspiration?

A

maximum amount of water that could be lost through evapotranspiration given an unlimited supply of water in surface water stores, soil and vegetation.

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24
Q

What are water budgets?

A

show the annual balance between inputs and outputs in an area

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25
Q

What is effective rainfall?

A

-amount of precipitation remaining after evaporation
-means that places can have very similar rainfall amounts can have different water budgets and experience different water issues

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26
Q

What is a river regime?

A

The annual variation in discharge of a river at a particular location
(long term)

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27
Q

What are factors affecting the characteristic of a river’s regime?

A

channel capacity of a river
area and relied of the drainage basin
volume, pattern and intensity of precipitation
climate
geology of the soil
anthropogenic activities (e.g dams)

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28
Q

What are storm hydrographs?

A

Represent the short term variation in discharge, days rather than years
Features include:
-rising limb= increase of river discharge
-peak flow= maximum discharge
-lag time= time delay between peak rainfall and peak discharge
-falling limb= discharge decrease
-base flow= discharge returns to normal level

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29
Q

What are the two types of storm hydrographs?

A

Flashy:
- short lag time
- high peak
- steep rising limb

Subdued:
- long lag time
-low peak
-gently sloping rising limb

30
Q

What are the physical factors creating flashy storm hydrographs?

A

Climate= intense storm exceeds infiltration capacity/ rapid snow melt/ low evaporation rates due to low temp
Lithology= impermeable rocks (granite)- rapid surface runoff
Soil=low infiltration rate
Relief=high and steep- more runoff
Basin size= small basin
Vegetation= low density- less interception
Pre-existing conditions= basin already wet from previous rainfall

31
Q

What are the physical factors creating subdued hydrographs?

A

Climate= steady rainfall < infiltration capacity
Lithology= permeable rocks (limestone)- allow for infiltration so reduce runoff
Soil=high infiltration rate
Relief=low and gentle slopes= less runoff
Basin size= large basin
Vegetation=high density- high interception= high evapotranspiration
Pre-existing conditions= basin dry + low water table

32
Q

How can drainage basins be managed?

A

Vegetation on roofs- increase interception and temporarily store water
permeable pavements- creating gaps between pavements to increase infiltration
Rainwater harvesting- collecting rainwater to use as domestic greywater
Creating wetlands= act as natural sponges and increase temporary water storage

33
Q

How does urbanisation impact drainage basins?

A

-Deforestation= soil becomes exposed and roots are lost= more soil erosion= increased surface runoff
-Impermeable surfaces= tarmac + concrete= impermeable= less infiltration= more surface runoff occurs
-Bridges= can act as dams= restrict channel flow= increasing pressure rivers under= worsen floods
-Drainage and sewage systems= reduce lag time= increased risk of flash flooding

34
Q

What is meant by the term deficit/drought?

A

an extended period of deficit rainfall relative to the long-term statistical average for a region
i.e when input is less than output
4 types of drought
meteorological to hydrological to agricultural to socioeconomic
-

35
Q

What is meteorological drought?

A

rainfall deficit over an extended period of time
i.e when long term precipitation is much lower than normal
Features include:
-low rainfall
-high temp
-strong winds

36
Q

What is hydrological drought?

A

stream flow deficit
i.e deficiencies in surface and subsurface water supplies e.g rivers, groundwater an reservoirs
Features:
-reduced infiltration
-low soil moisture
-little percolation and groundwater recharge
-reduced water stores

37
Q

What is agricultural drought?

A

when there is insufficient soil moisture to meet the needs of crops
soil moisture deficit
Features:
-low evapotranspiration
-reduced biomass
-fall in groundwater level

38
Q

What is socio economic drought?

A

food deficit
Features:
loss of vegetation
increased risk pf wildfires
soil erosion
desertification

39
Q

What are the causes of drought?

A

Physical/natural causes:
-ENSO (El Nino)= can produce cold Atlantic current which reduces evaporation and thus precipitation especially in Western Sahel

Anthropogenic Causes:
-Climate change = led to warmer sea surface temperatures in south Atlantic and Indian oceans causing the monsoon (ITCZ) to fail
-Air pollution= from Europe and North America has caused global dimming, affecting atmospheric circulation and the intensity of monsoon rainfall
-Population growth= increased food and fuel demand leading to over cultivation/grazing and desertification

40
Q

How do humans increase drought risk?

A

-over abstraction
-reservoir construction
-water transfer schemes
-deforestation
-overgrazing
-climate change

41
Q

What is ENSO?

A

El Nino-Southern Oscillation
-short term climate change cycle which occurs in the equatorial Pacific Ocean
-change in water body patterns within the Southern hemisphere leading to unusual weather conditions

-ENSO cycles are relatively predictable but their duration and intensity is not
-relationship between ENSO and anthropogenic climate change is also poorly understood however scientists do expect it to contribute towards increasing water insecurity in the future

42
Q

What is the Southern Oscillation?

A

a see-saw of atmospheric pressure between the Pacific and Indo-Australia area
-The Southern Oscillation Index (S0I)= been developed to monitor it, a sharp drop indicates the arrival of El Nino

43
Q

What are normal conditions in the Pacific Basin?

A

trade winds blow from east to west along equator
air pushes warm water westwards
thermocline, upwelling
warm, moist air rises, cools and condenses, forming rain clouds

44
Q

What are the conditions during an El Nino event?

A

occurs every 3-7years
usually lasts for 18months
trade wind pattern is disrupted-may weaken or reverse
so air circulation loop is reversed
weak upwelling of deep cold water
cool water normally found along Peru coast replaced by warm water
area of warmer water near Australia replaced by cooler water
trigger dry conditions throughout the world- annual monsoon rains in South Asia often weaken

45
Q

What are the conditions in an El Nina year?

A

sometimes follow an El Nino event
very strong trade winds
strong upwelling of deep coldwater
build up of cooler than usual subsurface water
can lead to severe drought conditions particularly Western Coast of South America
very strong air circulation and very warm water moving east-west

46
Q

What is the importance of wetlands?

A

-act as temporary water stores
-help mitigate from river floods due to sudden storm discharge
-trapping, recycling nutrients and pollutants
-habitat for a diverse food web
-provide clean water supply + food (fish)

47
Q

What are the physical causes of desertification?

A

▪ Reduced Precipitation:
vegetation dies= protective layer it provided for the soil
will also be removed= soil increasingly exposed to wind and rain= increased rate of soil erosion= worsening soil conditions. This may cause a positive feedback loop of worsening soil condition and vegetation death,
leading to desertification.

▪ Global Warming:
rise temperatures will increase the rate of
evaporation of water moisture= less water available for convectional rainfall= stunted plant growth= vegetation dies (leading to desertification as described
above).

48
Q

What are the human causes of desertification?

A

Population growth is the root cause of the recent increase in rates of desertification= pressure for food increases, agricultural methods change to supply the demand (e.g. cattle farming is becoming intensified resulting in large areas of forest being cut
down to provide enough land for grazing. Intensification of crop farming means the fallow
time between crop harvest and new planting will be reduced. These farming practices can
cause over-cultivation, trampling of vegetation and loss of soil nutrients which reduces
soil fertility. In addition, forests may be felled or slashed-and-burned to make room for new
farms or housing, further worsening soil quality and exposing the topsoil to erosion. Over
time, desertification will escalate in a positive feedback loop.

49
Q

What factors make a drainage basin more susceptible to surpluses/flooding?

A

-low lying land
-urbanised built environments
-small basins

50
Q

What are the causes of flooding?

A

-Intense rainfall
-monsoon rainfall
-snowmelt
-changing land use
-mismanagement of rivers

51
Q

How can flood risk be mitigated/adapted?

A

-Afforestation= reduce rapid surface runoff
-Restricting construction on floodplains= reducing potential economic and social loss and by reducing urbanisation maximise infiltration
-Establishing temporary extra flood plains, in the event of extreme weather - some UK councils have designated football pitches or parks next river, to reduce the flood risk for towns living close to the flood banks.

52
Q

What are the impacts of climate change on the hydrological cycle?

A

-if land and sea surface temp continues to rise so period between ENSO cycles could decrease
-increasing average temps will increase evaporation rates= could lead to potential droughts and increasing water scarcity
-rise in temperatures=leas to more convectional rainfall and enhanced tropical cyclone/depression intensity=more intense and periodic flooding
-water table drops= aquifers deplete=less water available in groundwater stores

53
Q

What is water security?

A

The capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water
For:
-sustaining livelihoods, human wellbeing, socio-economic development
-ensuring protection against water borne pollution and diseases
-preserving ecosystems

Water insecurity= occurs when theses conditions are not met

54
Q

Why has demand for water increased?

A

-Population growth= generally more people =more water needed
-Growing middle class as countries develop=increasing lifestyle and domestic demand
-Economic growth=industrial demand may also increase

55
Q

Why is increased demand an ussue?

A

-aquifers and deep water wells are being dug =especially for water intensive agriculture
-water tables (groundwater storage) are dropping as a result.
-water is being extracted at a faster rate than the soil is able to recharge.

56
Q

What is water stress?

A

deterioration in both the quantity of available water and quality- occurs when the demand for water exceeds the available amount during a certain period

57
Q

What is water scarcity?

A

Water scarcity=
Two types:
-Physical water scarcity= insufficient water to meet the demand; more than 75% of river flows are used for agriculture, industry and domestic use
-Economic water scarcity= water resources are available but there is insufficient capital to access the water in order to meet demand; less than 25% of river flows are used a result

58
Q

What is WPI?

A

Water poverty index
Used to measure localised water stress
5 components:
-Water resources – the availability and quality of water
-Access to water – the distance from safe water for drinking, domestic and industry use
-Handling capacity – management, infrastructure and income
-Use of water – for domestic, agricultural and industrial purposes
-Environmental indicators – ability to sustain nature and ecosystems

-each component is scored out of 20
highest scoring=Finland (78 total)
lowest scoring=Haiti (35 total)

59
Q

What are the physical and human causes of insecurity?

A

In many parts of the world there is a growing mismatch between water supply and demand
-UN suggests that water use has been growing at more than twice the rate of population increase in the last century
-estimated that by 2015 1.8 billion people will be living in countries/regions with absolute water scarcity
-two thirds could be living under water stress

Physical factors:
-precipitation= varies across different climates: mid latitude areas generally receive most rainfall
-topography= areas of high relief get more orographic precipitation= increased surface runoff= increased channel flow
-geology= permeable rocks can be infiltrated so water can e easily stored underground
-saltwater encroachment at the coast (can indirectly be caused due to anthropogenic climate change as sea levels rise)

Human factors:
-over-abstraction
-water contamination from agriculture
-industrial pollution

60
Q

What is saltwater encroachment?

A

movement of saltwater into an underground source of freshwater

61
Q

Why is water important?

A

Economic developement= needed to produce food, energy and manufactured

Human wellbeing=access to safe drinking water and sanitation is a human right

Ecosystems= depend on water resources but also work to regulate and restore them. Ecosystem degradation occurs when water quantity and quality falls

62
Q

Why does the price of water vary so significantly?

A

-Development= access to clean drinking water requires expensive infrastructure so developing nations like Kenya often rely on bottled water from street vendors which costs are up to 100times more expensive

-Privatisation= in many nations in the 1980s water supply was handed over to private companies e.g. Northumbria water which should encourage competition and make water cheaper yet is not always the case

-Efforts to reduce consumption= developed nations such as Denmark have increased costs to consumer in order to reduce consumption- Denmark has the highest water costs in the world

63
Q

Why is demand expected to fall by 2050?

A

-deindustrialisation= developed undergo deindustrialisation so reduction in water demand from manufacturing
-volumetric metering= now used in 2/3 of OECD nations which encourages more responsible domestic use
-energy efficiency= has increased in industry and homes e.g dual flush toilets/water efficient appliances
-flood imports/water conservation= efforts to reduce water use for irrigation

64
Q

What is meant by sustainable water management?

A

aim to balance economic, social and environmental needs by working with local people to develop soft engineering projects that work with natural processes to restore water supplies
-often involving water conservation
Tries to meet the need of all stakeholders:
-Economic= affordability for both consumers and government
-Social= equal access for all, especially those who are water poor
-Environmental= sustaining renewable water resources into the future while at the same time meeting demand and not degrading ecosystems.

65
Q

What are some soft engineering water conservation strategies?

A

-Metering/pricing
-Grey water recycling
-Smart irrigation
-GM crops
-Groundwater recharge

66
Q

What is intermediate technology?

A

Intermediate technology uses cheap and locally available resources to meet peoples needs:
-Rainwater harvesting jars
-Solar powered water pumps
-Bio-latrines

67
Q

What is integrated resource management?

A

a process which promotes the co-ordinated development and management of water, land and related resources in a sustainable way
IRWM is usually adopted at a river basin scale using water-sharing treaties
The Berlin rules (2004) apply to all countries and provide the international legal framework for sharing transboundary water resources.

68
Q

What are the advantages and disadvanatges of mega dams?

A

Advantages:
-Can provide a large volume of water
-Can generate HEP
-Reduces demand for groundwater

Disadvantages:
-floods land
-expensive
-increases evaporation
-areas downstream suffer from lack of water

69
Q

What are the advantages and disadvantages of desalination plants?

A

Advantages:
-Can provide a large volume
of clean water
-Reduces demand for
groundwater

Disadvantages:
-Energy intensive
-Releases lots of CO2
-Expensive
-Produces salt waste
-Expensive to build and
maintain

70
Q

What are the advantages and disadvantages of water transfer schemes?

A

Advantages:
-Can provide water for areas
that lack water and arid
areas
-Water can become a
valuable resource for
countries otherwise poor and
undeveloped

Disadvantages:
-Can dry up source areas
-Expensive
-Lots of water evaporated
-People relocated to
construct

Physical Geography (8 decks)

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