Water Cycle And Water Insecurity Flashcards
Closed system
Transfer of energy not matter between its systems and its surroundings
At a global scale the system is continuous
Nothing is lost or gained
Closed system
Effected by
Solar energy
Gravitational potential energy
Solar energy
Energy from the sun, heating water and causing evapotranspiration
Gravitational potential energy
Ways in which water accelerates under gravity and is transferred to river/sea
Fluxes between stores
Evaporation
Becomes water vapour, gains energy from solar radiation
Increases amount of water stored in atmosphere
Fluxes between stores
Condensation
Loses energy to surroundings
Water droplets can stay in atmosphere/ flow to other subsystems
Precipitation
Main flow of water to ground
Vary seasonally
Cryospheric process
Accumulation (build up of snow and ice) and ablation (melting of snow and ice) change amount of water stored
Global cold means greater inputs than outputs
Water transferred through snow
Change happens over different time scales
Fluxes
Annual movement of energy between different stores
Residence time
Time water remains in a store or takes to pass through
Global water budget
Accounts for all the water in hydrological cycle
Water must be physically and economically accessible (ground water hard to access)
Water with shorter RT contain fewer pollutants
Water that is non replenished (long RT) is non renewable such as water stored in cryosphere and fossil water
Drainage basin
An area of land that is drained by a river and its tributaries and separated from neighbouring drainage basins by a ridge of high land
Open system
Inputs and outputs total amount of water in system changes over time
Types of precipitation
(Inputs of drainage basins)
Frontal
Warm air is less dense than cool air so rises above and cools down
Orographic
When warm air meets mountains it’s forced to rise, causing it to cool
Conventional
When sun heats up the ground, moisture on the ground evaporates and rises up and cools
Flows of a drainage basins
Interception
Infiltration
Run off
Saturated over land flow
Through flow
Percolation
Groundwater
Outputs of a drainage basins
Evaporation
Transpiration
Channel flow/ river discharge
Influences inputs/ outputs/ flows of a drainage basins
Season and climate
Winter water freezes reduces size of flow increases store
Increases temperature ice melts increases flow/ outputs so more evaporation causes conventional
Impact vegetation/ interception and evaporation
Intense storms increase precipitation and peak discharge so larger inputs than outputs and increase flow
Influences inputs/ outputs/ flows of a drainage basins
Soil
Infiltration rates influenced by soil type/ structure
Through flow is faster through openings
Soil type impact type of vegetation
Influences inputs/ outputs/ flows of a drainage basins
Vegetation
It intercepts precipitation and slows it down which increased when greater vegetation
More water lost through evaporation
Reduces runoff and peak discharge
Influences inputs/ outputs/ flows of a drainage basins
Geology
Water flows slowly through most rocks
Permeable/ joints cause faster groundwater
Impermeable rocks stop water flowing though
Influences inputs/ outputs/ flows of a drainage basins
Relief
Steeper the gradients faster runoff and through flow
Surface stores have shorter RT contain fewer
effect amount of water discharge
How human actions have disrupt drained basins
Deforestation
Reduces interception and increases run-off
Reduces infiltration as less dead material
Soil erosion, more likely, limits infiltration, decreases groundwater
How human actions have disrupted drainage basins
Land use change
Plough and breaks up surface, decreases infiltration
Farming livestock, compacted ground decreases infiltration and increases run-off
Building and road impermeable surface which increases run-off
How human actions have disrupted drainage basins
Water storage reservoir
Creating new storage reservoirs by building dams increases freshwater to access
Decreases river discharge into ocean, creating large areas of standard water increases evaporation
How human actions have disrupted drainage basins
water abstraction
More extracted to meet the demands of a rising population decreases water in stores
During dry season more is extracted
Water budget
Shows balance between inputs and outputs in a water cycle
Helps farmers plan frequency and amount of irrigation needed
Precipitation equals channel discharge plus evaporation plus/minus change of storage
Water budget in the temperate zones
Jan to April water surplus (increase precipitation than evaporate transpiration. Full soil water stores.)
April to September soil water store depletes, decrease precipitation, increase evaporate transpiration water deficit
September to December decrease in temperature so decrease evaporation transpiration, increase precipitation so recharge in water soil stores
River regime
Variations of a river discharge over a year
River regime
Physical influence
High levels of run-off increases discharge of a river as more water enters the river increases volume
Season and climate affect precipitation
Geology and soil structure will affect amount and speed of infiltration
River Regime
Yukon river
Alaska and Canada
Very low discharge in river, but rapid rise in spring
Due to rapid snow melt increase temperature
So in Yukon basin permafrost – in permeable
Increase overland flow when snow melts
River regime
Amazon River
South America
More gradual rise in discharge
High levels of rainfall in most months, infiltrate quickly, thin soils and sedimentary rock
River regimes
Indus River
South and central Asia
Snow melt in Himalayan spring
During monsoon months input is precipitation
Dry monthly to water deficit
Basin made of igneous and metamorphic rock so less permeable
Increase volume in monsoon season
Flashy hydrographs
Short lag time and high peak discharge
Steep rising and falling limb
What are the factors affecting hydrographs?
Size of drainage basin
Drainage density
Relief
Permeability
Shape of drainage basin
Vegetation
Land use
Factors affecting hydrographs
Size of drainage basin
Large catches more precipitation so have higher peak discharge
Smaller has shorter lag times as precipitation has less time to travel so reaches main channel quicker
Factors affecting hydrographs
Drainage density
High, water enters river more quickly as more to flow into = flashy hydrographs
Low= flat hydrographs
Factors affecting hydrographs
Relief
Steeper, water flows quicker, shorten lag time
Less time to infiltrate and increase his run-off = flashy hydrographs
Factors affecting hydrographs
Permeability
Impermeable don’t store water so increase run-off
Increase peak discharge as more water reaches river faster = flashy hydrographs
Factors affecting hydrographs
Shape of drainage basin
Circular= flashy hydrographs
All points of watershed roughly same distance from where discharge is measured so lots of water reaches discharge point at the same time
Factors affecting hydrographs
Land use
Ploughed arable farm land= flashy hydrographs as less interception
Urban areas increase in permeable material which increases run-off
Summer increases water used decreases river discharge
Factors affecting hydrographs
Vegetation
More means more evaporate transportation so less run-off so lower peak discharge= flashy hydrographs
Vegetation intercepts and slows flows
Drought
A shortage of water over an extended period of time
Agricultural drought
Not enough water to grow a crop yield
Socio economic drought
Haven’t got enough water to meet the demand of people
Meteorological drought
Less precipitation entering a local system
Hydrological drought
Less water in groundwater stores, streams and rivers
Short term drought
Affect localised area due to precipitation deficit. Caused changes in frequency or frontal precipitation.
Also occur when cool descendant air creates high-pressure which blocks ascending warm air which creates clouds so decreases rain
Long-term changes in drought frequency
Climate change – long-term warming/cooling of oceans leads to change in frequency – decrease recovery time
Seasonal rain, unpredictable – longer-term depletion of ground water and reservoir stores
The Enso cycle
Natural change in patterns of ocean temperatures in the Pacific Ocean
The Enso cycle
El Niño and La Niña
In normal conditions there is low pressure western Pacific and high pressure over the east. Trade winds blow from East to West.
El Niño event, pressure increases western Pacific and decreases east. Trade winds weekend/West to East.
Sinking air in high-pressure – drought west (Australia). Less precipitation – wildfires.
El Niño every 3 to 4 years and last for 9 to 12 months
La Niña event, normal conditions become more extreme
Tradewinds increased strength, cold water to rise
dry conditions in east and wetter in the west
Occurs every 2 to 7 years
Aquifer
A saturated layer of permeable rock below the water table
Human activity increases risk drought
If demand is greater than precipitation, surface water stores dry up so abstract aquifer
Lead to over abstraction
Also divert water out of natural system and into homes and businesses
This water isn’t subjected to natural processes which reduces water supply in other stores
Australia (millennium drought)
Long-term meteorological drought 2001–2009
Natural low precipitation due to high-pressure area
El Niño increases conditions
Higher temperature so increase evaporation
Years of abstracting depleted groundwater stores
Water levels decrease so water water supply decreases impacted farming
And food prices increased
Number of sheep decrease due to dehydration, income decrease led to unemployment
Drought impact on ecosystem function
Wetlands have limited ecological resilience
Acts as a water purifier as trapped pollutant, but in drought dry up causes vegetation to die so species
Algae increases concentration which reduces O2 level levels so animals migrate
Forests under stress, tree growth slows, young trees die
As trees die land exposed to warmer temperatures wind erosion
Flood
An overflow water onto land that is usually dry
Flood plane
Low lying land either side of a river
Meteorological factors/causes of flood
Prolonged rainfall
Prolonged periods of heavy rainfall – slow onset of flooding
Series of low pressure systems move across the UK
Time gap between depressions is short, flooding is more likely
Meteorological factors/causes of flood
Intense storms
Intense storms has fast onset
High rainfall and storm surge causes flash flood flooding
Meteorological factors/causes of a flood
Extreme monsoonal rainfall
Seasonal change in prevailing wind
Climate change – heavier rain and longer
Increases run-off and saturated overland flow
Meteorological factors and causes of a flood
Snow melt
Upland glacier areas flooding occur in valleys due to ice melt
Increases overland flow, flood Upland reservoir
Occurs due to abnormally high temperature
Due to volcanic activity
A flood due to glacier melt water – Jokulhlaup
Meteorological factors and causes of a flood
Snow melt
Upland glacier areas flooding occur in valleys due to ice melt
Increases overland flow, flood Upland reservoir
Occurs due to abnormally high temperature
Due to volcanic activity
A flood due to glacier melt water – Jokulhlaup
Jokulhlaups
A flood caused by sudden release of glacial melt water from a subglacial lake
Melting is due to heat from a volcanic eruption
Surface glacier will hold this water until too large
Sudden deluge of water/ glacial outburst may contain ice fragments and eroded rock
