Summary AQA Alevel geography Water and Carbon cycle notes

Water and carbon Poppy Stone


Water and carbon
Systems in natural cycles
Types of stores:

 Atmosphere- in the air
 Hydrosphere- in water sources
 Lithosphere- in rocks
 Biosphere- in ecosystems
 Cryosphere- in ice

Aquifers

 They are natural water stores in the rock
 Many of these aquifers are being exploited unsustainably for irrigation
 This increases the risk of them turning into saline aquifers as seawater can then infiltrate
into rocks

Example: Ogallala aquifer

 It is located in central America beneath the Great Plains
 Formed as it used to be a land of low hills and shallow valleys. Streams then
began depositing sand into the valleys forming aquifer
 At risk of over-extraction and pollution due to agricultural irrigation
 Happening as the aquifer can’t keep up with human demands due to the
increasing population. Irrigation accounts for 90% of Ogallala groundwater usage


Groundwater- water held in rocks

 Young groundwater may be a more renewable resource
 As it is shallower it may be vulnerable to contamination

Cryospheric processes

 Accumulation- all processes that add snow or ice to a glacier/ floating ice or snow cover
 Ablation- the natural removal of snow or ice from the surface of a glacier or snow cover
 Sublimation- the conversion between the solid and gas phases of matter

The water cycle
Insolation- heat from the sun

Transpiration- movement of water through plants

Evapotranspiration- evaporation from any surface

Surface runoff (overland flow)- water that runs over the top of the ground

Surface storage- water stored on the earths surface in puddles or lakes

Infiltration- water moving directly down through soil

Soilwater- water held in the soil


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, Water and carbon Poppy Stone


Throughflow- water flowing through the soil parallel to the surface

Groundwater- water held in rocks

Groundwater flow- movement of water parallel to the earths surface through rocks

Dripflow- water dripping off leaves

Stemflow- water flowing down the stem of a plant

Interception- precipitation landing on plants or buildings

Types of hydrological cycles

Hillslope cycle (smallest):

 Open system
 Farming- ditches drain the land and encourage water to flow quickly to rivers
 Urbanisation- if the slope is developed to provide more housing impermeable surfaces will
reduce infiltration
 Deforestation- removal of trees reduces interception and infiltration
 Seasonal change- winter snowfalls and frozen ground

Global hydrological cycle (large scale):

 No inputs or outputs
 Closed system

Positive feedback- effects of an action are amplified by subsequent knock-on effects

 Rising sea levels and ice melt
 Ice shelves become unstable leading to increased calving so increased ice melt and further
sea level rise

Negative feedback- effects of an action are nullified by its subsequent knock-on effects

 Increased surface temperatures so increased evaporation from oceans
 More cloud covers and clouds block out sunlight so reduced temperatures

Cloud formation

 Dew point is the point where a gas turns into a liquid
 Formed by water being evaporated, then the warm air rises to dew point then it cools so
condensation can happen. Water droplets form on condensation nuclei then when the cloud
is heavy enough it will rain

Types of rainfall

Relief rainfall-

 Warm wet air is forced to rise over high land
 Formed when air cools as it rises over relief features such as mountains, as the air rises it
cools, condenses and forms rain

Frontal rainfall-

 The lighter warm air is forced to rise over the denser cold air

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