SG5: How humans can disturb and enhance the natural water and carbon cycles? Flashcards
What is a dynamic equilibrium?
When the inputs, throughputs, stores and outputs in a system are constantly changing state but in which in the long term maintain a balance. Negative feedback loop restore the balance.
What is a positive feedback loop?
Self enhancing
What is a negative feedback loop?
Self limitinh
How does growth of urban areas impact the water cycle?
- Infiltration reduced
- Drainage systems- remove surface water unable to infiltrate and percolate
- Water levels rise- river levels rise rapidly
- Invasion of floodplains- urban development increased risk to damage of housing area as water that has naturally soaked up the floodplains sits on the impermeable surface.
How does growth of urban areas impact the carbon cycle?
- Removal of vegetation- reduces biomass store of carbon
- Energy consumption- carbon emissions from transport, burning fossil fuels and industry increases as population increases.
- Cement manufacturing- increase in co2 emissions from cement manufacturing- more carbon released into the atmosphere.
How does farming impact the water cycle?
- Irrigation diverts water- groundwater and river water diverted to cultivated land and stored in the soil.
- Fluxes are lower- interception, evaporation and transpiration lower in aggro-ecosystems that in forest and grassland
- Ploughing increases moisture levels - soil moisture increases and there is increase run off leading to leaching.
How does forestry impact the water cycle?
- Increase interception loss
- Evaporation increases because more trees
- Lag time increases due to increased ability to intercept
- Transpiration higher
- Localised deforestation
How does forestry impact the carbon cycle?
- Changing land use - use forestry increases carbon store
- Forest trees extract co2
- Carbon sink
What is surface water extraction?
Extraction of water from rivers, lakes and reservoirs e.g. Iceland/
What case study is used for water extraction?
The Aral Sea
Where is the Aral sea?
Northern half is in Kazakhstan and southern half in Uzbekistan, in Asia.
When did water extraction start in the Aral sea?
Since the 1930s
Why was water extracted in the 1930s from the Aral sea?
To irrigate cotton and rice farms using irrigation canals.
Since when did the Aral sea begin to shrink?
1960s
Why did the aral sea begin to shrink?
More canals were being built. 70% of water leaked or evaporated out. The area has decreased from 70,000 km squared to 25,000 km squared and as from 2007 was about 10% of it’s original size.
