Global Systems Flashcards
When and why were Beijing residents advised to stay inside?
2013 - Air pollution was 20x higher than WHO recommended maximum level
Shanghai water pollution
In 2015, 85% of the water in the rivers were undrinkable
How much carbon will the Great Green Wall sequester?
250 million tonnes
How many jobs will the Great Green Wall create?
10 million
How many hectares does the Great Green Wall plan to plant?
100 million by 2030
What region is the Great Green Wall in?
Sahel
Evidence for Bergeron-Findeisen process
1 - Cloud seeding with dry ice generates rainfall
2 - In the UK precipitation is often derived from clouds with temperatures below -5 degrees
Melting snow VS fresh snow albedo
Melting - 40 to 60% reflected
Fresh - 75 to 95% reflected
What caused the 1987 Asian Drought?
El nino and weakness of SW monsoon
What is it called when precipitation lands on vegetation?
Interception
What is the time exposed to the sun called?
Insolation period
What happens as a result of leaf drip?
Rain splash erosion
Why can secondary interception be more important?
Raindrops reach maximum velocity after a fall of 9m, within height of canopies.
If a forest contains a high canopy above bare soil, terminal velocity erosion would be the same.
What is stemflow?
Flow of interception water down a trunk or stem.
What increases speed of stemflow?
Smooth bark and steep branches.
Why is throughflow sometimes more erosional than direct impact?
The droplets build up and are heavier
What dissipates energy of raindrops on the ground?
Leaf litter
What is transpiration?
Loss of water through stomata in leaves
Evapotranspiration
Combination of evaporation and transpiration
Why is transpiration from trees than crops?
Humid air next to leaves is more rapidly removed by air currents. Maintains steep diffusion gradient between stomata and atmosphere.
What is infiltration?
Absorbtion of water into the soil
Effect of leaf litter on infiltration
Adds organic matter to soil as it decomposes. Improves structure and permeability. More efficient infiltration.
What is throughflow?
Water deflected laterally by soil particles and impermeable components (e.g. rocks)
Surface runoff
Water unable to infiltrate. Collects on surface and then flows away over the surface.
Splash erosion effects
Soil aggregates broken up, thrown in air. Carried away or can block soil pores. Runoff accelerated.
What is a drainage basin?
Area of land where water drains into a body of water.
Geology and drainage basins
Permeability determines underground storage
Metamorphic e.g. Granite cause runoff
Gravels store best if unconsolidated
What marks the boundary between 2 drainage basins?
Watershed - found along high ridges
Where is throughflow more likely to be found?
Vegetated slopes. Interception prevents runoff and soil pipe networks formed by creatures like earthworms provide routes.
What is the permanently saturated zone within rocks and sediments called?
Phreatic zone
What is the water table?
The upper limit of the phreatic zone
What are aquifers?
Very large underwater resevoirs
What is fossil groundwater?
Groundwater no longer being recharged.
E.g. Libya using it for agriculture.
How fast is london water table rising?
2m a year
Worst industrial pollututers
Not big industries (more regulated)
Small and medium
Israel method of aquifer recharge
Pumping water into pits and wells
Why do Israel have to recharge aquifer?
High extraction rates
Salt-water intrustion from Mediterranean
