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The Hydrological Cycle (Storm Hydrograph (Lower flatter graph -> large…
The Hydrological Cycle
Water Cycle System
Stores
Atmosphere
Lithosphere
Cryosphere
Hydrosphere
Aquifers
Body of permeable rock that stores and transfers water
Mostly sandstone and chalk- porous rock
1/2 the worlds largest aquifers are being depleted
Water infiltrates then percolates
Supplies 35% of water to people
Flows
Infiltration (down through soil)
Groundwater Flow (sideways through rock)
Throughflow (Sideways through rock)
River Discharge (through a river)
Channel flow (out of drainage basin into river)
Percolation (down through rock)
Surface runoff (over land to river channel)
Stem flow (down plants)
Feedback loops
Rising sea levels -> melting -> rising sea levels
Increased temps -> ice melts -> less albedo -> more sun rays -> increased temps
Increased vegetation -> more CO2 absorbed -> slowed rise in temps
Dynamic Equilibrium
Causes of variation
Deforestation
Floods/drought
Climate Change
Urbanisation
Causes of Change
Processes of Change
Precipitation, Evaporation, Condensation, Sublimation, Interception, Overland Flow, Throughflow, Infiltration, Percolation, Groundwater Flow
Causes of Change
Climate Change
Cloud Formation- temporal and spatial variation in precipitation
Cryospheric Processes- Globa warming causing glacial ablation
Local Causes of Change
Deforestation
Urbanisation
Farming
Storms
Seasons
Seasonal Changes
Precipitation greater in winter
Vegetation absorbs more in summer
Evaporation greater in summer
More soil water in winter
River channel flow greater in winter
Drainage Basins
Area of land drained by a river and its tributaries
Definitions
Watershed- high land forming edge of drainage basin
Source- where a river begins
Mouth- Where river meets the sea
Confluence- Two river meet
Tributary- small river joins larger
Channel- where a river flows
Inputs & Outputs
Precipitation
Sun’s Energy
Evapotranspiration
Channel flow output
Storm Hydrograph
Lower flatter graph -> large basins, slower transfer
Short lag time, high peak -> flash flood
Peak Discharge- highest amount of water
Lag Time- Time between rainfall and peak discharge, depends on basin shape and drainage density
Base flow- amount usually in river
how much it can hold before it floods
Falling limb- How long it took to get back to normal
influenced by geology
River Exe, Devon
Wimbleball reservoir
150 hectare
Used to regulate water supply to Exeter
Characteristics
0.6% urbanised
65% is run off
84% impermeable rock
High flood risk
Exmoor Mires Project
Drainage ditches had been dug for farming, increased speed of drainage
Project aimed to restore peat bogs
Increase water content
Improve water quality, reducing sediment carried
Protect Biodiversity
By 2015:
Restore 1000ha of peatland
Block 100km of ditches
Raise water table by 2.6cm
Reduce water drained by 2/3
The Carbon Cycle
Causes of Change
Human
Combustion of Fossil Fuels
Urbanisation
Farming
Deforestation
Physical
wildfires
Volcanic activity
Natural Climate Change
Impact of temperature
Cold water holds more carbon
Carbon released from warming oceans
More weathering
Decomposers more efficient with heat
Temperature affects forest coverage- respiration and photosynthesis
Cold- more ice, less ocean- less sediment flows
More permafrost- stores carbon
The Rainforest
Water Cycle
Precipitation > 2000mm a year
Canopy intercepts 75% of rainfall
Deforestation
Reduced evapotranspiration
Reduced interception
Run off increases
Could lead to 20% decline in regional rainfall
Carbon Cycle
Ideal climate for plant growth
Wood is 50% carbon
Decomposition
Deforestation
Slash and Burn
Decrease in photosynthesis
plant and animal respiration falls
decomposers become absent
Introducing crops and pastures to deforested areas reintroduces stores and flows but at a much lower level
Indonesia
Biodiversity
1/3 of all species are endangered- Sumatran Tigers, red orangutans
estimate half of all species are unrecorded
1% of worlds land area- 10% of plant species, 12% of mammal species and 17% of bird species
3rd Largest area of rainforest on earth
Rainforest used to cover 80% of Indonesia- now only 49%
Deforestation
Impact on Water Cycle
Plants ove water from ground to atmosphere- impacts global rainfall patterns- deforestation can lead to widespread drought
Transpiration reduces global warming as it absorbs energy from the surrounding area
Causes
Demand for wood and paper
Farming and mining
840,000 hectares lost in 2012
palm oil demand accounts for 16% of all deforestation
Impact on carbon cycle
carbon sinks
release CO2 when cut down
since 1850, deforestation has accounted for 40% of global warming
Forest Fires
Created by slash and burn
2015- worst fires for 20 years
2.6 million hectares burned
Peat soil is very flammable
Positive feedback
Global warming -> drought -> more forest fires
Water, Carbon and Life on Earth
Carbon in life
18% of Human body
50% of tree biomass
Essential for photosynthesis- start of the food chain
Keeps the earth warm
Human interventions
Modifying photosynthesis
Plantation forests absorb lots of CO2
Modifying Land Use
Carbon farming- crops that absorb more CO2
Carbon Capture
Boundary Dam in Canada- cut emissions by 19%
Modifying Deforestation
Certified wood, Forestry Stewardship Council
Paris Agreement
Stores and Transfers
Stores
Fossil Fuels
Soil and Peat
Oceans
Almosphere
Sedimentary rock and ocean sediment
Land Plants
Transfers
Photosynthesis
Respiration
Decomposition
Combustion
Burial and Compaction
Sequestration- (transfer from atmosphere)
Weathering
Th Exchange of Carbon across the four spheres
Fast
Biosphere
CO2 released to atmosphere in respiration
Animals absorb carbon when eating
Carbon released through excretion
CO2 from atmosphere for photosynthesis
release from decomposition
Lithosphere
Extraction and combustion of fossil fuels moves them from slow to fast cycle
Hydrosphere
Carbon exchanged between upper layers of ocean and atmosphere
Slow
Hydrosphere
marine organisms' shells- compressed into sedimentary rock
Lithosphere
soil respiration or erosion, organic matter lithified into natural gas- fossil fuels
Atmosphere
Chemical weathering by carbonic acid