Chapter 5 - The Hydrosphere Flashcards
What are 4 reasons that the global demand for water is increasing ?
Global demand for water
- increase in population
- increase in per-capita use with increased affluence
- Increased irrigation of farmland
- industrialisation
How can deforestation affect the hydrological cycle ?
Human impacts on the hydrological cycle
Less trees means that there is a reduction of precipitation downwind because more water infiltrates through soil or runs of into rivers
what is one way that agriculture affects the hydrological cycle ?
Human impacts on the hydrological cycle
soil compacted by heavy machinery cannot be infiltrated by water easily so soil moisture drops and runoff increases
how does urban development effect the hydrological cycle ?
Human impacts on the hydrological cycle
Urban expansion means that there is a larger area of impermeable surfaces which will increase runoff
what is one way global climate change affects the hydrological cycle ?
Human impacts on the hydrological cycle
higher global temperatures affects the rate of melting, evapouration and condensation which all affects the timing and rate of precipitation
How can building a resevoir alter the habitat ?
Water abstraction: Rivers & Reservoirs
flooding destroys previous habitats but also could create new valuable ones
How can building a resevoir alter the wildlife barrier ?
Water abstraction: Rivers & Reservoirs
dams & reservoirs act as barriers to wildlife that may have previously migrated down the river
How can building a resevoir alter the sedimentation ?
Water abstraction: Rivers & Reservoirs
sediments reaching the reservoir will settle there and not travel further downstream. Can deprive river banks further downstream of sediment making them more vulnerable to erosion
What are 2 ways that resevoirs may be used to provide water ?
Water abstraction: Rivers & Reservoirs
- regulate river flow (holding back water at times of surplus etc)
- Changes to flow fluctuations can change river erosion & sedimentation so therefore development of meanders
Describe the rivers flowing into the Aral sea
over-exploited rivers EXAMPLE
- Rivers supplying the Aral sea flow through central Asia
- Since 1960s huge irrigation schemes for growing cotton & rice has caused river flow into the sea to decline, sometimes to zero
- Area of lake was reduced by 90% and pollution by pesticides, fertilisers and industrial waste caused serious issues
- Disagreements & conflicts between the countries that the river runs through
- Abstraction for irrigation reduces flow downstream
What is an aquifer ?
Water abstraction: Aquifers
body of rock which holds water that’s exploited as a resource
What are 3 features of an aquifer ?
Water abstraction: Aquifers
- porosity
- permeability
- assosiated geological structures
how are aquifer water levels depleated ?
Water abstraction: Aquifers
If the rate of extraction exeeds rate of recharge
Normally how does aquifer recharge take place ?
Water abstraction: Aquifers
Precipitation lands on the soil and infiltrates and perculates through the soil
why are changes in surface hydrology a consequence of overexploited aquifer ?
Water abstraction: Aquifers
lead to lowering of the water table, this can reduce supply of water to wetlands, lakes, rivers etc and they may dry up
why are changes in Subsidence a consequence of overexploited aquifer ?
Water abstraction: Aquifers
there are air spaces left where water previously was, these cannot support the weight of rock above so the ground becomes compacted (causes subsidence at the surface which damages pipes and buildings)
why are Salt water incursion a consequence of overexploited aquifer ?
Water abstraction: Aquifers
if the aquifer is over exploited seawater may flow into the aquifer to replace lost water (Salt makes aquifer water unsuitable for irrigation as will kill plants by osmosis dehydration)
why are Reduced supplies a consequence of overexploited aquifer ?
Water abstraction: Aquifers
if extraction rate exceeds recharge, volume available for abstraction will be reduced
Describe the features of the north china plain aquifer
Overexploited aquifer EXAMPLE
- Largest agricultural region in China, has fertile soil but few rivers so groundwater is used instead for irrigation
- Growing demand for irrigation water & growing population has caused the water table to lower by around one metre per year
What measures are introduced to manage the north china plain ?
Overexploited aquifer EXAMPLE
- Low pressure irrigation pipes to reduce leaks
- Proposal of growth of crops which require less water to grow
- Consumers charged for volume of water they use in order to encourage water conservation
What are 3 ways water availability affects life ?
Exploitation of new sources of water
- quality of life
- which industries can be developed
- where people can live
What are 5 methods of using water, thats not an aquifer ?
Exploitation of new sources of water
- rivers
- resevoirs
- rainwater
- estuary barrage
- seawater
What is an estuary barrage ?
Exploitation of new sources of water
A freshwater reservoir created by building a dam across an estuary where a river enters the sea
How is rainwater collection performed ?
Exploitation of new sources of water
- header tank connected to roof to collect
- if this ovefflows it goes to an underground tank
- if this overflows then it recharges aquifers
4 factors affecting the usefulness of a river for water exploitation
Exploitation of new sources of water
- total annual flow
- flow fluctuations
- level of natural contaminants
- pollution from humans
1 Positive and 2 negatives of an estuary barrage
Exploitation of new sources of water
+ fewer land use conflicts
- change important intertidal habits
- can be polluted by human activity
What is artificial recharge of aquifers ?
Sustainable management of water
Where surplus water is unable to infiltrate so it is pumped elsewhere (eg. underground lagoons)
What does an interbasin transfer do ?
Sustainable management of water
Canal & pipe systems transfer water from areas of surplus to areas of deficit
What are 3 reasons we would use afforestation to create sustainable water sources ?
Sustainable management of water
- trees reduce soil erosion + reduce surface runoff
- Reudce fluctuations in river flow
- Reduces flooding after heavy rain + maintains levels during low rainfall
what are 3 ways to lower the volume of water usage ?
Water conservation
- low water appliances
- low volume irrigation
- Xeriscaping
what is Xeriscaping ?
Water conservation
management of gardens, parks & open spaces by planting them with plants that require less water
what is grey water ?
Water conservation
retaining water that has been used but is still quite clean and can be reused for other purposes (water used for bath or showers)
what does a water metre do and why would we use it to help water conservation ?
Water conservation
Water metres match volume of water used to the price charged, encourages people to use less
What is the order of the water treatment process ?
Water Treatment
sedimentation → screens → Aeration → Flocculation/ coagulation & clarification → Filltration → activation of carbon filters → sterilisation → pH control → flouridation → ion exchange → reverse osmosis → distillation
