The water cycle and water insecurity Flashcards
Aquifer?
A permeable or porous rock which stores water
Channel flow?
The water flowing in a rivulet, stream or river contained within the banks
Closed system?
A sequence of linked processes with a transfer of energy but not matter between parts of the system
Cryosphere?
Describes the set of all locations on earth where water is found in solid form, including areas of snow, sea ice, glaciers, permafrost, ice sheets and icebergs
Deficit?
Where a resource is less than the necessary amount
Drainage basin?
The area of land drained by a river and it’s tributaries. Drainage basins are separated by a ridge of high land called the watershed
Economic water scarcity?
Occurs when water resources are available but there is insufficient capital to access the water to meet demand
Evapotranspiration?
Combined loss of water to the atmosphere via the processes of evaporation and transpiration
Flux?
The flow or flowing of a liquid
Fossil water?
Water that has been contained and undisturbed for millennial. There is no significant recharge therefore it is a non-renewable resource.
Global water budget?
The amount of water transferred and stored in the earths hydrological cycle each year.
Hard engineering?
Often hi-tech and high-cost engineering schemes such as dams or Thames barrier
Hydrological drought?
Occurs when there is insufficient soil moisture to meet the needs of vegetation at a particular time
Infiltration?
The movement of water vertically downwards via spaces (pores) in the soil.
Interception?
The process by which raindrops are prevented from called onto the ground via leaves, branches, twigs of vegetation.
Monsoon?
A seasonal prevailing wind which causes wet and dry seasons in many sub-tropical areas
Open system?
A sequence of linked processes with inputs and outputs, including transfers of energy and matter to and from other systems.
Orographic?
Relating to mountains, orographic uplift if when the uplift of an air mass, because of orographic obstruction, causes the cooling of air mass. If enough cooling takes place, condensation can occur and form into orographic precipitation.
Percolation?
A process similar to infiltration but travelling through rock surfaces towards the water table.
Permafrost?
Zone of permanently frozen water found in high latitude soils and sediments
Permeability?
The ability of a substance to allow another to pass through it, especially porous rock, sediment or soil to transmit fluid through pores and cracks
Physical water scarcity?
Occurs when there’s physical lack of available freshwater resources to meet demand due to over-abstraction by agriculture, industry and domestic activity
Porosity?
A surface that allows water to pass through it, such as sand
Precipitation?
Any form of water falling from the sky
Relief?
The range of topographic elevation within a specific area
Resilience?
Ability to recover/adjust easily to an event or change
River regime?
The pattern of river discharge over a year; usually there are seasonal variations
Runoff?
Water (from rain, snowmelt etc) that flows over the land surface; can be due to soil saturation
Saltwater encroachment?
Where saline water beings to find it’s way into fresh water aquifers, especially near coastal aquifers which run low, allowing salt water to see back in and cause contamination
Saturated overland flow?
Occurs when the soil becomes saturated, and any additional precipitation causes runoff
Storm hydrograph?
Shows changes in a rivers’ discharge at a given point on a river over a short period of time (usually before, during and after a storm)
Water budget?
The annual balance between inputs (precipitation) and outputs (evapotranspiration and channel flow) at a place
Water security?
The capacity of a population to safeguard sustainable access to adequate quantity’s of acceptable quality water.
Water stress?
When demand for water exceeds the available amount during a certain period. Renewable water resources are between 1000 and 1700m
What is a closed system?
A system that does not allow a transfer of matter in or out of the system
Inputs of hydrological cycle?
Ocean precipitation
Land precipitation
Stores of hydrological cycle?
Ice Ocean Soil moisture Groundwater Rivers, lakes Land Vegetation
Flows/processes of hydrological cycle?
Ocean to land water vapour transport
Surface flow
Ground water flow
Outputs of hydrological cycle?
Ocean evaporation
Evaporation, transpiration
What type of system is the hydrological cycle?
A renewable one: no new water can enter the system and no new water can be lost
What is the water circulation in the hydrological driven by?
Solar energy- suns heat causes evaporation and transpiration
Gravitational potential energy- water accelerates under gravity causing it to flow
Why is fossil water considered non-renewable?
Will require significant amount of energy to obtain
Taken out of the store and not replaced
Of the fresh water present, where is most of it?
Locked up or bellow surface as ground water
Where is 68% of water found?
In icecaps or glaciers
Where is 30% of water found?
Groundwater
What does ITCZ stand for?
Inter tropical convergence zone
What type of pressure can be found at the equator?
Low pressure
What type of pressure can be found at the tropics?
High pressure
What type of pressure can be found at the polar regions?
High pressure
How many cells of circulating air are there?
Six
Why is the sun most intense at the equator?
Suns rays are most concentrated here
What does intense solar radiation result in?
Rising air
What type of rainfall can be found at the equator?
Convectional rainfall
What type of system is the drainage basin?
An open system within the closed global hydrological cycle
What is the definition of a drainage basin?
An area of land drained by a river and its tributaries with a boundary, usually composing of hills and mountains
What are the 5 main stores in the drainage basin?
Channel storage Groundwater storage Surface storage Soil moisture storage Interception storage
What is the main input in the drainage basin?
Precipitation
What are the 7 main flows in the drainage basin?
Throughfall Stemflow Surface runnoff Infiltration Groundwater flow Percolation Channel flow
What are the 3 physical factors that affect the drainage basin INPUTS?
Seasonality
Variability (long term changes to climate)
Latitude
What is interception?
Process by which raindrops are prevented from falling directly onto ground surface by a layer of vegetation
What is Infiltration?
The movement of water vertically downwards through pores in soil
What is Surface runoff?
Water flows overland, rather than permeating deeper levels of the ground.
What is Throughflow?
A down slope movement under the influence of gravity towards a stream or river through the soil
What is Percolation?
Water moves from the ground or soil into porous rock or rock fractures. The rate is dependent on the fractures that may be present + the permeability of the rock
What is groundwater flow?
The gravitational transfer of water through porous rock, under the influence of gravity. Water can sometimes become trapped within these deep layers of bedrock, resulting in aquifers.
What is infiltration capacity?
Is the maximum rate at which the soil can absorb precipitation
What is soil capacity affected by?
Soil composition
Previous precipitation
Type and amount of vegetation
Relief of land
What is the primary transfer of water to river channels?
Surface runoff
What are the 6 physical factors affecting drainage basin FLOWS?
Interception Infiltration Surface run off Through flow Percolation Groundwater flow
What are the two physical factors affecting drainage basin OUTPUTS?
Evaporation
Transpiration
What is transpiration?
A biological process where water is lost to atmosphere via pores of plants (stomata).
What is transpiration affected by?
Seasonality
Vegetation
Moisture content
What is evaporation also dependent on?
Volume and surface area of the water body
Vegetation cover
Colour of surface beneath the water
What are the 3 rainfall types?
Conventional
Frontal/cyclonic
Relief/orographic
Conventional rainfall?
Often a daily occurrence. Morning heat warms the ground in turn heats low level moisture which evaporates and rises. It cools and condenses to form rain. Very common in tropical climates.
Frontal/cyclonic rainfall?
Where two air masses meet, a wedge can occur of hot air within cold air (a depression). At the front, warm moist air is forced to rise above the cold air mass, causing the water moisture within it to cool and condense
Relief/orographic rainfall?
When warm moist air meets land of high relief, the air masses are forced to rise above the hill to continue travelling. As it rises, air masses cools and the moisture in it hun it condenses to form clouds and rainfall.
What are the 6 human (anthropogenic) factors that disrupt the drainage basin system?
Cloud seeding Urbanisation Change in lane use Deforestation Dan construction Ground water abstraction
Over abstraction?
When water is taken from aquifers, ground water levels fall. If the amount of water taken is greater that the amount it water falling it is called over abstraction
Groundwater abstraction?
When water us taken out faster than it is replaced (from aquifers), causing reduced ground are flow and a lower water table
Dan construction?
Dams reduce downstream river flow and discharge, increased surface stores thus means more evaporation
Cloud seeding?
This is in an attempt to change the amount of precipitation by dispersing substances into the air that serve as cloud condensation nuclei
Urbanisation?
Creates impermeable surfaces that reduces infiltration and increases surface runoff and through flow via artificial drains: river discharge increases as a result
What are 4 impacts on drainage basin due to reservoir construction?
Reduce river flow bellow the, leading to loss of vegetation
They abstract water from the drainage basin
Salinity levels can rise as water evaporates
In tropics, mats of floating plants on water surface makes evapotranspiration rates 6x higher than in open water
Water budget equation?
Precipitation= channel discharge + evapotranspiration + change in water storage
5 ways in which the Amazon forests can effect the hydrological cycle?
Risks to wildlife
Risks indigenous tribal communities
Precipitation can arrive in bursts causing floods
Affect water supplies of Brazilian cities
Winds blowing over uneven forest canopy creates turbulence, which allows atmosphere to absorb moisture
What does the water budget give a direct comparison to?
Natural water supply and demand- can identify a positive water balance and when there is a drought risk
What are the 6 characteristics on a soil moisture budget graph show?
Soil moisture surplus Soil moisture utilisation Maximum annual temp Soil deficiency Soil moisture recharge Field capacity
Soil moisture surplus
Precipitation is greater than evaporation thus meaning the soils moisture increases
Soil moisture utilisation
As temp increases, so does evaporation. The soil uses the moisture gained during its surplus, used up by plants etc
Maximum annual temp
The point of maximum evaporation= highest risk of drought. Soil moisture is now used up. Precipitation likely to be used up, no run off, river levels will fall
Soil deficiency
Despite evaporation decreasing, there is not enough precipitation to provide for vegetation. Plants must adapt to survive
Soil moisture recharge
Occurs when potential evapotranspiration decreases so that it is lower than precipitation, soil begins to fill again
Field capacity
Soil moisture is now full, additional rainfall will relocate to the water table and groundwater stores will be recharged
What slowly feeds the river system?
Groundwater during between periods of rain
Simple river regime?
Seasonal variation in regime- periods of high discharge followed by low discharge (glacial melt water and monsoons) cause sudden fluctuations in river input
Complex regime?
Tend to occur for larger rivers that cross different reliefs and climactic zones thus experience different climactic effects eg Ganges
What are 7 characteristics affecting the characteristics of a river regime?
Channel capacity Vegetation Area and relief of drainage basin Climate Volume, pattern and intensity of precipitation Geology of soil Anthropogenic factors
What are the 5 characteristics on a hydrography?
Rising limb Peak flow Lag time Falling limb Base flow
What limb on a flashy storm hydrography is always steeper?
Rising limb
Rising limb?
The increase of river discharge, not instantaneously after precipitation
Peak flow?
The maximum discharge, delayed after maximum precipitation has occurred
Lag time?
The tine delayed between peak rainfall and the peak discharge
Falling limb?
As the storm precipitation levels decrease, discharge will in turn decrease over time
Base flow?
Eventually, the discharge will return to a normal level
Flashy storm hydrograph?
Means that the graph depicts sharp vertical jumps and equally steep vertical declines.
5 features of a flashy storm hydrography
Short lag time High peak Low infiltration rate Urbanised High water table
Subdued storm hydrograph?
‘Delayed’, or ‘flat’ hydrographs
5 features of a subdued storm hydrograph
Long lag time Low peak Gently sloping rising limb High infiltration rate Low water table
What does SUDS stand for?
Sustainable drainage systems
What is an example of a SUDS?
Permeable pavement, green roofs
Drought?
A period of deficit rainfall
What are the 4 types of drought?
Meteorological
Agricultural
Hydrological
Socio economic
Meteorological drought?
When longer term precipitation is much lower than normal
Agricultural drought?
When there is insufficient soil moisture to meet the needs of crops
Hydrological drought?
When there are deficiencies in surface and sub surface water supplies eg rivers
Socio economic drought?
When the water demand from people and industry exceeds water availability
What type of hazard is drought?
Hydro-metrological hazard
What results in shortened seasons and severe droughts?
When the ITCZ does not show up, blocked by stable high pressure
El nino?
The appearance of warm surface water from time in Eastern equatorial pacific ie a warmer event
La nina?
The appearance of colder than average sea surface temperatures in the central and East equatorial pacific ie a colder event
The southern oscillation?
Is a see-saw of atmospheric pressure between the pacific and Australia area
The southern oscillation index?
Represents the difference in average air pressure measured at Tahiti and Darwin, Australia
What are the two main causes of drought?
Climactic Variability
El ninio
What enhances the causes and effects of drought?
Climate change
Desertification?
Once productive land gradually changing into a desert like landscape
How are humans increasing desertification process?
Via positive feedback
Positive feedback?
Enhances or amplifies change, moving a system away from its equilibrium state and making it more unstable. It creates a ‘snowball effect’.
Negative feedback?
Decreases the amount of change by reducing some of the inputs, returning the system to stability.
What is the greatest environmental challenge and how many people are affected by this?
Desertification
2 billion people
What are the two ways in which humans can increase drought risk?
Direct (reservoir construction)
Indirect (climate change)
What are the three main causes of desertification?
Animals grazed in higher numbers to feed people
Ground is farmed more intensely
Reduction of forest cover and vegetation (exposed ground)
How does climate change impact the environment?
Making temperature hotter and rainfall less reliable
What is the desertification process?
No plants or leaves intercept the rainwater and soil is left to exposed sun which bakes the ground. Rainwater does not soak in soil so it degrades losing fertility and structure.
What does drought result in?
Famine
Migration
Terrorism etc
Impact of drought on rainforests?
Younger trees die, reducing the canopy cover
Tree litter can catch fire due to being exposed to tropical sun = wildfires
Impact of drought on wetlands?
Increase tree mortality= less animal habitats
Wildfires
Reduces cattle ranching
Two main meteorological causes of flooding?
Intense rainfall
Prolonged, heavy rainfall
What can meteorological processes increases?
Increases inputs in hydrological cycle causing a surplus of water in system
What does an increase of inputs in the hydrological cycle cause?
Freshwater floods
How much of the lands area does freshwater flooding affect?
1/3 of land’s area
What do most freshwater floods result from the presence of?
Low atmospheric pressure systems
What are the three main factors that cause flooding within a low atmospheric pressure system?
Intense monsoonal rainfall
Rapid snow or ice melt
Prolonged and heavy rainfall associated with passage of depressions
Intense rainfall characeristics?
Severe thunderstorms= convectional rainfall
Channel capacity is quickly exceeded resulting in flash flooding
Prolonged, heavy rainfall in the mid latitudes?
Come in the form of depressions
Prolonged, heavy rainfall in the sub tropics?
During the wet phase of a monsoon
Depressions?
An area of low pressure. Air rises in a depression so clouds and rainfall are formed. Depressions therefore bring unsettled weather and rain. Winds are normally stronger.
Where do depressions form?
Over the Atlantic Ocean and are carried across Britain by westerly winds.
What is the main reason for the UKs changing weather?
Depressions
Monsoon?
A seasonal reversal in wind direction. Brings prolonged, heavy rainfall
Water scarcity?
Renewable water resources are between 500 and 1000m
Absolute water scarcity?
Renewable water resources are very low: bellow 500m per capita
Renewable water resources?
The long term annual average total of internal and external renewable water resources?
What is the link between water and human causes of water stress?
Human factors increase outputs or degrade supplies
What is the link between water and physical causes of water stress?
Lead to reduced inputs
What are the two main physical causes of water stress?
Climate variability
Saltwater encroachment
What are the three main human factors that can lead to water stress?
Over abstraction
Industrial pollution
Agriculture
How can climate variability lead to water stress?
In warmer climates= increased evaporation and transpiration = less precipitation
Higher water temp can encourage bacteria growth
How can saltwater encroachment lead to water stress?
Global sea level rise, localised groundwater abstraciona and thermal expansion are all enhancing risks of saltwater encroachment
How can over abstraction lead to water sress?
Too much water is removed from groundwater to that supplies diminish
What % of the worlds aquifers are exploited?
20%
How can industrial pollution lead to water stress?
Waste and chemicals are released into the water supplies
How can agriculture lead to water stress?
Excessive water withdrawals (inefficient use= depleted aquifers and habitats)
Chemical fertilisers can get into water supplies
What are the two main processes operating within the hydrological cycle on a global and local scale?
Rain
Snow
Biosphere?
Made up of the parts of Earth where life exists—all ecosystems
Why could the hydrological cycle be possibly viewed as an open system?
Due to the input of solar energy which drives fluxes and flows
Why is the hydrological cycle a closed system?
There are no losses or gains of water over time
What % of the worlds water is freshwater?
2.5%
Blue water?
Water in our surface and groundwater reservoirs ( river, lakes)
What % of freshwater is accessible to us in the form of blue water ?
0.3%
What are three of the main contributing factors to unequal water distribution?
Climate, demand, human development and population growth
What impact do human activity have on the water distribution system?
Can cause local water shortages due to the transfer of water between different parts of the system
What % of water do human withdraw of the worlds annual freshwater runoff?
8%
What % of the 8% freshwater withdrawal is used for irrigation?
7%
What % of water returns to the atmosphere after being used for irrigation?
6.3%, the rest runs as grey water
Grey water?
Partly degraded/polluted water- bathtubs, showers, sinks, washing machines
What % of water returns to the atmosphere after being used for industrial activity?
0.6%
What % of water returns to the atmosphere after being used for industrial activity?
0.12%, the rest runs as grey water
What % of water returns to the atmosphere after being used for domestic and commercial use?
0.4%
What % of water returns to the atmosphere after being used for domestic and commercial use?
An equal amount is evaporated and lost via runoff, some runs as black water
Black water?
The mixture of urine, feces and flushwater along with anal cleansing water
What type of water stores have short turnover times?
Renewable water stores
What type of water stores have much longer turnover times?
Non-renewable water stores
Turnover time?
measure of the movement of an element (water) in a biogeochemical cycle
What are the three main ways humans can increase flood risk?
Urbanisation
Agricultural development
Mismanagement of rivers
Agricultural development?
Farming upstream of urbanised floodplains can result in flooding downstream: soil compaction and deforestation
Mismanagement of rivers?
Straightening channels in urban areas can result in flooding: increase discharge and the natural channel may not be able to cope
Channelization?
Straightening the river channel
How do you measure the flood frequency?
Calculated by observing how often a flood of a certain magnitude occurs in a given .location or time period
What is flood frequency expressed in?
Return periods or recurrence intervals e.g. A 1 in 100 year flood meaning the flood magnitude is only to occur once in an 100 year period
Return periods?
An average based on historical data (flood magnitude), it gives the estimated time interval between events of a similar size or intensity.
What does IPCC stand for?
Intergovernmental panel on climate change
What does the IPCC predict regarding climate change?
That increasing greenhouse gas concentrations will have a considerable impact on the global hydrological cycle
Globally, what is there an increase of?
Precipitation intensity
What does the increase of precipitation intensity due to climate change result in?
A depletion of stores and a faster hydrological cycle- a wetter atmosphere
What will changes in run off due to climate change result in?
Less water stored as groundwater
Rapid snow melt= flashy flooding
Some regions will experience limited runoff
In terms of drought, how will this worsen due to climate change?
Greater level of evapotranspiration and limited amount of surface storage
How unequal is the worlds water supply?
Proportion of worlds water that is accessible for human is very small: 1%- not equally distributed and demand is too high
What does the water availability gap refer to?
How water is not equally distributed and demand is too high
In terms of water distribution, what country factors are important?
Physical geographical factors such as climate and development level such as affluence and population size
What % of water is contained in just 10 country?
60%
What % of worlds population live in areas receiving only 25% of worlds annual rainfall?
66%
How much has water usage increased between the years of 1900-2000?
85%- set to increase further
What are the three main causes that impact the water availably gap?
Diminishing supplies
Rising demand
Competing demand from users
What are some examples of rising demand that impact water supplies?
Population growth
Economic development
What are some examples of diminishing supplies that impact water supplies?
Impact of climate change
Deteriorating quality from the population
Water pressure point/ water hotspot= supplies under threat
What are some examples of competing demand from users that impact water supplies?
Internal conflicts in a basin
International issues upstream and downstream
Main PHYSICAL factors affecting water supply?
Topography
Geology
Climate x precipitation
River systems
The physical factors affecting water supplies on a regional scale?
Geology
Topography
Snow fall and glaciers
River systems
The physical factors affecting water supplies on a global scale?
Climate
How does climate affect water supplies?
Precipitation varies across different climates: mid lat receives most rainfall
Seasonal and highly variable
How does topography affect water supplies?
Areas with high relief generally get more precipitation and surface runoff is greater for more inclined planes, so channel flow tends to be larger so water can be easily stored in dams and reservoirs
High relief allows for cryosphere storage
How does geology affect water supplies?
Controls the distribution of aquifers and groundwater storage- permeable rocks can be infiltrated, water can be stored easily underground
Why is geology important in terms of groundwater?
Groundwater regulates flows and provides an even supply of water throughout the year, provided natural recharge can keep up with abstraction
How does river systems affect water supplies?
Are important for regional water supplies- a significant source of water for multiple counties
How do snow and glaciers affect water supplies?
Their seasonal thaw feeds into river systems.
How does the global atmospheric pressure system play a big role in water security?
Makes the mid lats and equatorial regions water secure
When does water scarcity occur?
When there’s less than 1000m cubed per capita of water available
What % of the worlds counties face physical scarcity, where more that 75% of their blue water flows aren’t being used?
2.5%
By 2050. what % of people will be experiencing water scarcity?
1.5 billion people
Economic water scarcity?
Don’t have enough money to invest in new technology, lack of governance etc
What is water still scarce in countries with satisfactory physical availability?
Poor management
Privatisation
Gov corruption
Human factors that affect water supply?
Pollution Industrial pressure industrial activity Over extraction Saltwater encroachment
As a direct result of limited supply, what has happened to price of water?
Price of clean water has increased
What does the increase in the price of water affect?
The access of water
Four sustainable ways to manage the drainage basin?
Growing vegetation on roofs- increase interception
Create permeable pavements- increase infiltration
Rainwater harvesting- collecting rainwater
Creating wetlands- act as natural sponges in
What are the impacts of allowing human development on a basin to occur?
Deforestation, tree felling and slash-and-burn- soil erosion and more surface runoff
Impermeable surfaces- more surface run off
Bridges can act as dams on some rivers- restricts channel flow
Drainage and sewage systems will reduce lag time- flash flooding risks
How does wet lands act as temporary water stores within the hydrological cycle?
Act as giant water filters which traps and recycles nutrients and pollutants which maintains water quality
