🌍 elss sg5 Flashcards
(54 cards)
SG5!!! what is a positive feedback loop
self enhancing, accelerates original change
what is a negative feedback loop
self limiting, ultimately reverses original change
what is dynamic equilibrium
despite inputs and outputs of a system constantly changing in short term, in long term, a balance will be maintained
example of dynamic equilibrium in the water cycle
heavy rainfall = saturated ground, eventually water comes back up to surface through springs, rivers remove water so water table returned back to normal
example of dynamic equilibrium in the carbon cycle
fossil fuel combustion = higher atmospheric co2 = more photosynthesis = atmospheric co2 removed
how does urbanisation affect water cycle
- soil replaced by concrete (impermeable) so water can’t infiltrate
- more surface storage = more surface run off = higher flood risk
- drainage systems take water to rivers quickly = higher flood risk
how does urbanisation affect carbon cycle
- vegetation removed = less photosynthesis
- more co2 emissions from cars, homes, industry etc
how does farming affect water cycle
- irrigation systems mean lots of water lost by ET
- soil becomes very saturated = surface storage = surface run off = flood risk
- less interception by crops than trees
- ploughing creates channels for water = soil erosion
how does farming affect carbon cycle
- less biomass storage
- less soil storage as organic matter is exposed to oxidation
- soil is exposed so organic matter is removed by wind/rain
how does forestry affect water cycle
- more interception & interception loss
- less saturated soil = less run off = smaller flood risk
how does forestry affect carbon cycle
- more photosynthesis = more co2 storage in biomass
- more soil respiration = co2 released
- trees only becomes carbon sink 100 years after planting and by this time they may have been felled
what is the surface water extraction case study
the aral sea
aral sea location
in central asia in between kazakhstan and uzbekistan
when was the water extraction from the aral sea
1930s onwards
why was the water extracted from the aral sea
to develop irrigated cotton & rice farms in the area
what was the impact of the water extraction on the aral sea
water leaked or evaporated so less water to the sea.
by 2007, the sea was 10% of original size
what was the impact of water extraction from the aral sea on local climate
- less evaporation = less local rainfall
- seasons became more extreme as the sea kept the area cool in the summer as water was cool, and warm in the winter as the water warmed up over the summer
what is the groundwater extraction case study
london basin
what is water table
top of saturated zone
what is an unconfined aquifer
permeable rock that holds water that is not capped by impermeable rock
what is an aquitard
non porous rock which restricts flow of water from an aquifer
what is a confined aquifer
permeable rock that holds lots of water that is capped by impermeable rock
what is a recharge area
where a confined aquifer is unconfined
what is artesian pressure
creates a basin with a syncline
