Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
1. Systems ap- - Helps understand the physical + human world. May be open (linked to other
proach systems) or closed (entirely self contained)
- Ecosystem: describes the interrelationships between living and non living com-
ponents within a particular environment.
- A system comprises stores with transfers between them.
2. Systems defini- - Input: Material/energy moving into the system. eg: precipitation
tions - Output: Material/energy moving out the system. eg: runoff
- Energy
- Stores: eg: trees/lakes/soil
- Transfers: The relationships between the components. eg: infiltration, evapora-
tion
- Positive feedback: Cyclical sequence of events that amplifies/increases change.
(bad) eg: Rising sea levels destabilises ice sheets ’Increases rate of calving ’
Increased melting ’More rising sea levels
- Negative feedback: Cyclical sequence of events that reduces/neutralises the ef-
fects of a system, promoting a state of dynamic equilibrium. eg: Increased surface
temperature ’Increased evaporation ’Increased cloud cover ’Reflects radiation ’
Cooling the surface
Dynamic Equilibrium: is a state of balance within a system. It can be upset by...
[human/ physical factors like...]. When upset this can lead to...
3. Global water cy- - Water constantly being recycled, stored, transferred between land, oceans, at-
cle mosphere.
- Severe water shortages lead to migration + famine
- Ownership of water is a controversial political issue - future wars about it.
- Only 2.5% of all water is freshwater
- Uneven distribution
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
4. Major water - Hydrosphere (liquid water) 96.5%
stores - Atmosphere 0.001%
- Cryosphere (frozen water - ice + snow) 1.7%
- Lithosphere (land) 1.7%
- 97.4% Earth's water is saline (salty), mainly in Oceans.
- 69% freshwater stored as snow + ice sheets, 30% groundwater
- Rivers, lakes, atmosphere contain very low amounts on global scale.
5. Transfers in Wa- - Precipitation + Evaporation
ter Cycle - Evapotranspiration is the combination of evaporation and transpiration. It trans-
fers water from drainage basin to atm. (not just from vegetation). Water lost from
vegetation through stomata.
- Water may infiltrate soil, then percolate through rocks, then very slowly as
groundwater flow
6. Aquifers - Over 30% of all freshwater stored in rocks below ground surface, forming vast
underground reservoirs - aquifers
- Major aquifer systems in S.America and Europe. Sustains civilisations worldwide.
- Aquifers form in porous and permeable rocks below ground surface: Chalk,
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
sandstone. (pores = contain air pockets)
- Water enters the rock either directly (when exposed on ground - ppt./runoff) OR
very slowly (percolation)
- Soils vary in their capacity to store + transfer water - soil water budget.
- Porous sandy soil holds little moisture as water is easily transferred through the
pore spaces. Clay soil tends to store water + limited transfers.
7. Water table - Upper level of saturated rock. Rises and falls in response to groundwater flow
+ water abstraction by humans + by recharge (additional water flowing into the
rock)
- Water table needs to be maintained at same level - equilibrium
8. Fossil aquifers - Formed thousands of years ago when climate was wetter in deserts of Africa,
Middle East, Australia
- Aquifers being exploited unsustainably - more water abstraction
- Saline aquifers exist where seawater has infiltrated into the rocks often due to
over abstraction. ’Issue if sea levels rise (sea water infiltrates into pedosphere) Also
30% freshwater comes from aquifers - need to preserve
- Need to extract water from aquifers at same rate as ppt. (equilibrium) or will run
out.
- Economic development determines extent to which aquifers can be exploited (eg:
can afford desalination)
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
9. Residence times - Soil water: 1-2 months (may quickly soak into soil, transpired by plants, evapo-
water cycle rated)
- Rivers: 2-6 months
- Seasonal snow cover: 2-6 months
- Glaciers: 20-100 years
- Lakes: 50-100 years
- Groundwater shallow: 100-200 years
- Groundwater deep: 10,000 years
These varying time scales important to understand complexity of transfers within
water cycle. Can vary place to place.
10. Climate change - Last Ice age (18,000 years ago), about 1/3rd of Earth's land was covered by
effects of water glaciers and ice sheets.
cycle - With water locked up as snow and ice, the magnitude of this store increased
significantly but sea levels fell by over 100m compared to present day.
- During interglacial periods (3M years ago) Ocean levels were 50m higher than
today as cryosphere store decreased. ’Why we are concerned about possible
impacts of global warming on sea levels.
11. Water cycle - Precipitation, evaporation (+ evapotranspiration), condensation (formation of
processes of clouds)
change - Interception, overland flow/runoff
- Infiltration, percolation, groundwater flow (very slow water transfer through
rocks)
- Throughflow (water flowing through soil towards a river channel)
(+ Sublimation - solid ice to gas)
Study online at https://quizlet.com/_gd2334
1. Systems ap- - Helps understand the physical + human world. May be open (linked to other
proach systems) or closed (entirely self contained)
- Ecosystem: describes the interrelationships between living and non living com-
ponents within a particular environment.
- A system comprises stores with transfers between them.
2. Systems defini- - Input: Material/energy moving into the system. eg: precipitation
tions - Output: Material/energy moving out the system. eg: runoff
- Energy
- Stores: eg: trees/lakes/soil
- Transfers: The relationships between the components. eg: infiltration, evapora-
tion
- Positive feedback: Cyclical sequence of events that amplifies/increases change.
(bad) eg: Rising sea levels destabilises ice sheets ’Increases rate of calving ’
Increased melting ’More rising sea levels
- Negative feedback: Cyclical sequence of events that reduces/neutralises the ef-
fects of a system, promoting a state of dynamic equilibrium. eg: Increased surface
temperature ’Increased evaporation ’Increased cloud cover ’Reflects radiation ’
Cooling the surface
Dynamic Equilibrium: is a state of balance within a system. It can be upset by...
[human/ physical factors like...]. When upset this can lead to...
3. Global water cy- - Water constantly being recycled, stored, transferred between land, oceans, at-
cle mosphere.
- Severe water shortages lead to migration + famine
- Ownership of water is a controversial political issue - future wars about it.
- Only 2.5% of all water is freshwater
- Uneven distribution
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
4. Major water - Hydrosphere (liquid water) 96.5%
stores - Atmosphere 0.001%
- Cryosphere (frozen water - ice + snow) 1.7%
- Lithosphere (land) 1.7%
- 97.4% Earth's water is saline (salty), mainly in Oceans.
- 69% freshwater stored as snow + ice sheets, 30% groundwater
- Rivers, lakes, atmosphere contain very low amounts on global scale.
5. Transfers in Wa- - Precipitation + Evaporation
ter Cycle - Evapotranspiration is the combination of evaporation and transpiration. It trans-
fers water from drainage basin to atm. (not just from vegetation). Water lost from
vegetation through stomata.
- Water may infiltrate soil, then percolate through rocks, then very slowly as
groundwater flow
6. Aquifers - Over 30% of all freshwater stored in rocks below ground surface, forming vast
underground reservoirs - aquifers
- Major aquifer systems in S.America and Europe. Sustains civilisations worldwide.
- Aquifers form in porous and permeable rocks below ground surface: Chalk,
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
sandstone. (pores = contain air pockets)
- Water enters the rock either directly (when exposed on ground - ppt./runoff) OR
very slowly (percolation)
- Soils vary in their capacity to store + transfer water - soil water budget.
- Porous sandy soil holds little moisture as water is easily transferred through the
pore spaces. Clay soil tends to store water + limited transfers.
7. Water table - Upper level of saturated rock. Rises and falls in response to groundwater flow
+ water abstraction by humans + by recharge (additional water flowing into the
rock)
- Water table needs to be maintained at same level - equilibrium
8. Fossil aquifers - Formed thousands of years ago when climate was wetter in deserts of Africa,
Middle East, Australia
- Aquifers being exploited unsustainably - more water abstraction
- Saline aquifers exist where seawater has infiltrated into the rocks often due to
over abstraction. ’Issue if sea levels rise (sea water infiltrates into pedosphere) Also
30% freshwater comes from aquifers - need to preserve
- Need to extract water from aquifers at same rate as ppt. (equilibrium) or will run
out.
- Economic development determines extent to which aquifers can be exploited (eg:
can afford desalination)
, Water & Carbon Cycle AQA A level geography
Study online at https://quizlet.com/_gd2334
9. Residence times - Soil water: 1-2 months (may quickly soak into soil, transpired by plants, evapo-
water cycle rated)
- Rivers: 2-6 months
- Seasonal snow cover: 2-6 months
- Glaciers: 20-100 years
- Lakes: 50-100 years
- Groundwater shallow: 100-200 years
- Groundwater deep: 10,000 years
These varying time scales important to understand complexity of transfers within
water cycle. Can vary place to place.
10. Climate change - Last Ice age (18,000 years ago), about 1/3rd of Earth's land was covered by
effects of water glaciers and ice sheets.
cycle - With water locked up as snow and ice, the magnitude of this store increased
significantly but sea levels fell by over 100m compared to present day.
- During interglacial periods (3M years ago) Ocean levels were 50m higher than
today as cryosphere store decreased. ’Why we are concerned about possible
impacts of global warming on sea levels.
11. Water cycle - Precipitation, evaporation (+ evapotranspiration), condensation (formation of
processes of clouds)
change - Interception, overland flow/runoff
- Infiltration, percolation, groundwater flow (very slow water transfer through
rocks)
- Throughflow (water flowing through soil towards a river channel)
(+ Sublimation - solid ice to gas)
