The Hydrosphere Flashcards
What are the different reservoirs of water in the water cycle?
oceans
land ice
ground water
the atmosphere
living organisms
lakes and rivers
soil moisture
What does residence time mean?
average time a water molecule spends in a reservoir
What does transfer rate mean?
how much water moves over a period of time (molecules per min)
How do you work out residence time?
volume of water in reservoir/ mean transfer rate
Which reservoir has the longest residence time?
groundwater
Which reservoir has the shortest residence time?
living organisms
Which reservoirs does water move between during this process: evaporation
oceans to atmosphere
Which reservoirs does water move between during this process: precipitation
atmosphere to ground
Which reservoirs does water move between during this process: transpiration
plants to atmosphere
Which reservoirs does water move between during this process: runoff
land to ocean
Which reservoirs does water move between during this process: interception
atmosphere to plants
Which reservoirs does water move between during this process: infiltration
surface to soil
Which reservoirs does water move between during this process: percolation
downward movement of water through soil
Which reservoirs does water move between during this process: ground water flow
soil to rock
Which reservoirs does water move between during this process: transport by wind
over ocean to over land
Which reservoirs does water move between during this process: surface flow
unconfined flow of water over ground surface
Where does the energy come from that drives the water cycle?
the sun - drives evaporation
What does abstraction mean?
taking water from its natural reservoir for human use
How do human activities affect processes of the water cycle: urbanisation
reduces infiltration and ground water
increases surface runoff
increases interception (building use), slows down movement of water
How do human activities affect processes of the water cycle: abstraction
from groundwater - causes subsidence - increases surface level reservoirs
from oceans - increases water in living things
How do human activities affect processes of the water cycle: agriculture
increased abstraction and transpiration
decreased infiltration
soil gets compacted due to heavy machinery
How do human activities affect processes of the water cycle: deforestation
decreased transpiration, interception, infiltration
exposed soils, reduces water in atmosphere
How do human activities affect processes of the water cycle: afforestation
increased transpiration and interception
decreased infiltration
How do human activities affect processes of the water cycle: combustion of fossil fuels
increased evaporation and precipitation
more water in the atmosphere, speeds up water cycle
How do human activities affect processes of the water cycle: industry
increased atmospheric stores
decrease surface stores and evaporation
extracts water from ocean and rivers
Factors that cause the demand for water to change: population
increased pop = increased demand
Factors that cause the demand for water to change: change in affluence
increased affluence = increased demand = increased appliance use and activites
Factors that cause the demand for water to change: type of industry
chemical production = increased water
service industry = decreased water
Factors that cause the demand for water to change: agriculture
intensive agriculture = increased water
What is most of the water used for in the service industry?
energy production
Reasons for the increase in demand of domestic water use
more accessible appliances
growth of urbanisation
population growth
Reasons for the increase in demand of agricultural water use
more intensive agriculture to meet demand
Reasons for the decrease in demand for industrial water use
moved from heavy industry to service industry
Define water footprint
a measure of the volume of fresh water utilized by a country/person/community/business
Why is Kuwait the most dependent country for water imports?
hot
high population density
high affluence
Why does chocolate have such a high water footprint?
to run the machines
chocolate crops require a lot of water
Why does Brazil have the highest renewable water resources in the world?
amazon river used for HEP
Abstractive uses of water
drinking water
appliances
industry
recreation
agriculture
mining
power stations
transportation
Exploitation of the River Nile
population increase = overfishing
wetland degradation, deforestation, expansion of farmland = decreasing flow
urban settlements = polluting water
HEP dam in ethiopia = political unrest = The Nile Basin Initiative promotes cooperation amongst 11 countries in NE Africa
Uses of the River Nile
domestic, industrial, agricultural
banks contain rich soil due to flooding
Exploitation of the Rivers of Tibet (Mikong River)
increase in population = more pressure on resources
over 100 dams under development for HEP
167 hydropower plants
dams prevent fish from migrating = do not reach spawning grounds
Uses of the Mikong River
3 billion dollar fishing and agriculture industry
25% of global freshwater catch
supports crucial growth of crops
What is a reservoir (man made)?
an artificial lake where water is stored
Why do we build reservoirs?
to store the rain during wet seasons for drier years
domestic use, flood risk management, HEP, agriculture, industry
Advantages of reservoirs
floodwater control
power generation
irrigation
recreational use
clean supply of water
water for transport
HEP
Disadvantages of reservoirs
loss of high quality agricultural land
displacement of people
impacts fish migration
expensive
water transfer between river basins is expensive
Environmental impacts of reservoirs: habitat change
upstream of dam = flooded = becomes a freshwater habitat
downstream of dam = drier = grassland, woodland
Environmental impacts of reservoirs: wildlife migration barriers
dams stop the natural flow of water
Environmental impacts of reservoirs: changes in the river flow downstream of dams
less water arrives downstream
river becomes smaller = lower water availability for downstream habitats
Environmental impacts of reservoirs: sedimentation
river flow decreases = particles settle
sedimentation behind dam reduces space in reservoir
Environmental impacts of reservoirs: microclimate
HSHC
moderates extremes of temp
Factors that affect reservoir location: topography
ideal location = valley with steep sides and a river running through
Factors that affect reservoir location: geology
impermeable bedrock
Factors that affect reservoir location: catchment area
larger catchment area = fuller reservoir
Factors that affect reservoir location: water supply
high precipitation levels
Factors that affect reservoir location: pollution risk
pollutants become concentrate
(e.g. agrichemicals and sewage)
Factors that affect reservoir location: sedimentation
determine rates of soil erosion and catchment area
Factors that affect reservoir location: infrastructure
access roads already built = cheaper and easier
Factors that affect reservoir location: existing land use and land use conflicts
designations/agriculture/urban settlements
What is an estuarine barrage?
a dam built across the mouth of a river, creating a reservoir
Disadvantages of estuarine barrages
expensive
difficult to build
acts as a migration barrier
causes sedimentation
creates an obstacle for transport
damages intertidal wetlands
Define aquifer
a body of permeable rock that can contain or transmit groundwater
How does porosity contribute to the formation of an aquifer?
allows water to be stored underground
What does porosity mean?
a measure of a rocks ability to hold a fluid
How does permeability contribute to the formation of an aquifer?
allows water to pass through from the surface
What does permeability mean?
a measure of the ability of a material to transmit fluids
How do geological structures contribute to the formation of an aquifer?
impermeable rocks prevent drainage
syncline basin
What is a confined aquifer?
below land surface that is saturated with water
What is an unconfined aquifer?
rock is directly open at the surface of the ground and ground water is directly recharged
What is an artesian well?
a well drilled into an aquifer underneath the water table
natural water pressure pushes the water up and out
Consequences of aquifer overuse: reduced supplies
limited supplies for agriculture, industry and domestic use
less food security
migration of people due to famine
Consequences of aquifer overuse: subsidence
overextraction leaves pore spaces empty, causing them to collapse
Consequences of aquifer overuse: changes in surface hydrology
disappearance of surface water features if levels drop below water table
Consequences of aquifer overuse: ecological impacts
loss of freshwater habitats
local extinction of species
migration of species
imbalance in food chains
Consequences of aquifer overuse: saltwater incursion
overextraction causes permeable rocks to absorb saltwater
cannot use water for drinking, irrigation or industry
long residence time = long term problems
How can we monitor aquifer water levels and rates of depletion?
boreholes
NASA - GRACE satellites
How do boreholes monitor aquifer levels?
physically measure the level of the water table (rising or falling?)
How do GRACE satellites monitor aquifer levels?
measures gravitational pull of the aquifer
greater the mass = greater the pull
What is the most important aquifer in the UK?
the london basin
water table is rising above the underground system = flooding
What is the London Basin used for?
domestic and service supplies
historically used for industry
How has the water table changed in the SE over the years?
started to rise since less water is being extracted
Define aquifer recharge
the natural filling of an aquifer
How is the London Basin recharged?
precipitation percolates through the ground
How is rainwater harvested in modern buildings?
rainwater collected on rooftops
installing gutters on roofs
ground level catchment basins
New ways of exploiting water
sewage treatment
desalination
new aquifers
reusing agricultural draining water
cloud seeding
How are aquifers recharged artificially?
remove water from reservoirs where there is a surplus and transfer it to the aquifer
How can reservoirs be used to regulate river flow?
maintains flow at moderate levels all year round
What is meant by inter basin transfer?
surplus of water in one basin is moved into a basin that has been depleted
How can afforestation help with water supplies?
interception = slows down flow of water
more water infiltrates to become ground water
more vegetation = increased organic matter in the soil
How can we reduce domestic water consumption?
water meters
How can we reduce agricultural water consumption?
drip irrigation = crops only take up water when they need to
Impact of high turbidity
blocks light for photosynthesis
ruins aesthetics
Impacts of pH extremes
cause corrosion of pipework
denatures cells and enzymes
metals dissolve faster in acidic conditions
Impacts of high calcium content
precipitate may build up on pipework appliances
Impacts of high pesticide concentration
harmful to non-intended insects
many are liposoluble = builds up = effects magnify up the food chain
Impacts of high heavy metal concentration
toxic
affects CNS and cognitive ability
Impacts of dissolved oxygen
supports bacteria that decompose organic matter
Impacts of chlorine retention
allows water to kill pathogens over a period of time
What does the presence of E.coli suggest?
polluted water
Methods of freshwater treatment: screening
water passed through metal grids
removes large items
Methods of freshwater treatment: sedimentation
water stored in tanks for a number of days, allows suspended solids to settle out
Methods of freshwater treatment: aeration
air bubbled through water to stimulate aerobic bacteria
bacteria breaks down organic matter, killing anaerobic bacteria
Methods of freshwater treatment: flocculation
chemicals added to remove charges on particles (e.g. clay), allowing them to clump together
Methods of freshwater treatment: filtration
water percolates through sand and gravel beds
removes bacteria and remaining particles
Methods of freshwater treatment: activated carbon filters
small carbon crystals added
pesticides adsorb to the crystals
Methods of freshwater treatment: sterilisation
add chloring/UV/ozone
removes pathogens
Methods of freshwater treatment: pH control
neutralises water
Methods of freshwater treatment: fluoridation
add fluoride to water
resolves public health issue
Methods of freshwater treatment: ion exchange
ion exchange resins are added
metal ions adsorb to the resin
removes metals
Describe the process of reverse osmosis
water molecules forced through semi-permeable membrane at high pressure, salt can’t pass through
energy intense and expensive
remaining salt water returned to the ocean
Describe the process of distillation
evaporate salt water
capture and condense water vapour
salt remains in original container
requires large energy input = expensive
