W&C - The Water Cycle: Global Scale Flashcards
What are the percentages of stores of water globally?
97% oceans
3% freshwater - 69% ice caps and glaciers, 30% groundwater, 1% surface/freshwater
What are the four main stores of water globally?
Hydrosphere, atmosphere, lithosphere, cryosphere
What is the hydrosphere?
All liquid water
What is the lithosphere?
All water stored in the crust and upper mantle
What is the atmosphere?
Water vapour
What is the cryosphere?
All water stored as ice
What are aquifers?
Underground stores of water, and are unevenly distributed
Draw the earth with the 3 cells and global atmospheric circulation
In my notes!!!
Describe The Intertropical Convergence Zone (ITCZ)
- Solar radiation hits the equator directly
- causes warm air at the equator to rise and spread towards the ferrel cells
- the area where warm air is rising has low pressure, and condenses when it rises
- leads to cloud formation and encourages rainfall
- (high pressure prevents cloud formation and therefore rainfall)
- since the earth is on a 23 degree axil tilt, as it orbits the sun, the ITCZ moves between the tropic of cancer and the tropic of capricorn
- results in the formation of seasons - some countries experiences a dry climate while others a very wet one
- Example = India lies near the tropic of cancer, so in the July, when the ITCZ reaches the toc, there are high amounts of rainfall in the summer (also why there are a lot of monsoon in India)
What are the physical changes to the global water cycle over time?
Cryospheric processes
- accumulation and ablation, which result in rising and falling sea levels
- ablation decreases cryospheric stores globally
- increasing with climate change
- if all of the ice caps and glaciers around the world melted, sea levels would rise by 60m
Storm events
- sudden increases in rainfall can lead to flooding - increases hydrospheric stores
- also replenished lithospheric stores (not long term)
Droughts
- depletes major stores of water and can be a long term problem as they become more common with climate change
What are the human factors changing the the global water cycle over time?
Water abstraction
- being increasingly use as population and demand increases
- extraction > replenishment, so the stores are rapidly declining
- reduces volume of water in surface stores
Changing land use
- deforestation
- urbanisation
Farming practices
- pastoral farming = compacts the soil as livestock tramples on it, which reduces infiltration
- arable farming = plants provide interception and also increase evapotranspiration
Define discharge
The volume of water flowing in a cross sectional point of a river, at any given time
What is discharge measured in?
Cubic metres (cumecs)
Define rising and falling limb
Rising = increasing river discharge
Falling = decreasing river discharge
What is baseflow?
The volume of groundwater flow