the hydrosphere Flashcards
what is the hydrological cycle driven by
solar power (warms water to evaporate and rise in atmosphere and energy is converted to gravitational potential, converted to kinetic as it falls towards the sea)
how does solar power drive the hydrological cycle
warms water to evaporate and rise in atmosphere and energy is converted to gravitational potential, converted to kinetic as it falls towards the sea / drives evaporation from the land and the plants that lose water by transpiration
list 3 abstractive uses of water
domestic (toilets, washing, drinking) / industrial (power stations, chemical industry, for cooling, heating, washing and steam generation) / agriculture (feeding crops and livestock, irrigation)
why is irrigation used
crops can be grown in very dry areas, so plants close their stomata to stop water loss, which stops absorption of co2 and therefore growth. to max plant growth and stop them drying out, also acts as nutrient uptake as can only be absorbed by roots if dissolved in water
name 4 non-abstractive uses of water
energy (hydroelectric power, cool condenser steam in fossil fuel, and then returned to the source) / transport (mass transport for goods, seas, canals and rivers) / recreation (sailing, canoeing, sport fishing, swimming) / wildlife conservation (wetlands or reservoirs and flooded gravel pits- important for migratory water birds, mild winters prevent water from freezing)
why are rivers a good source of water
long and accessible, short residence time so quickly self-cleaned
state 4 main features that affect the usefulness of a river
total annual water flow (river channel discharge) / flow fluctuations / level of natural contaminants / pollutants from human activities
how can rivers be used with storage reservoirs
stores water in times of surplus to be used in time of a shortage - flood prevention.
list 9 things of consideration when considering reservoir locations
topography, geology, sedimentation, catchment area, water supply, existing land use, pollution risk, estuarine barrages
why is topography important to reservoir location
needs a narrow exit and large deep basin so a relatively small dam can hold lots of water, helps financially
why is geology important to reservoir location
rock beneath reservoir must be impermeable so water can’t infiltrate into rock and be lost, must be strong enough to support weight so it doesn’t subsidies or trigger an earthquake
why is water supply important to reservoir location
rainfall or river inflow should be regular with large volume, climate shouldn’t be too hot or too dry, would cause excess evaporation losses
why is existing land use important to reservoir location
the use of land to be flooded can be important, urban areas and conservation areas would be protected and agriculture wouldn’t be so much
why is pollution risk important to reservoir location
the land uses shouldn’t pose a serious pollution risk to the water, main threats are heavy metals and agricultural pesticides
why is it bad for climate change for build up of dead vegetation in a reservoir
it would decay anaerobically and release methane, which impacts climate change
why is sedimentation important to reservoir location
soil erosion in catchment area could make the water very turbid, resulting in sedimentation, could reduce water volume
why is infrastructure important to reservoir location
building a dam, treating water, and transportation requires workers, building material and access routes, so convenient site near dam is better than a site that would supply more water but isolated
why is estuarine barrages important to reservoir location
dam across a estuary can create a freshwater lake that can be used for water supplies
give 4 environmental effects from reservoirs
habitat change (flooding destroys habitats, but also creates new ones, barrier to wildlife like salmon that migrate along the river, important in recolonising) / changes in river flow (water may be abstracted from reservoir and pumped into consumers, regulate river flow, hold back in surplus) / sedimentation (reservoirs have a low flow rate, so sediments can’t be carried down stream, important in building up river banks and coastlines / reservoir microclimate (higher specific heat capacity of water reduces temperature fluctuations, cooler summers, water provides less friction than land so more wind, greater evaporation - increases humidity)
name 3 porous rocks that form aquifers
chalk, limestone and sandstone
name 3 permeable rocks
chalk, limestone and sandstone
why do substances like clay have low permeability
because it has many pores but they’re too small for water to flow through so has low permeability
name 2 impermeable rocks that are good for sitting below aquifers
granite and clay
why must rock above aquifers be at least a little permeable
to allow recharge with water from above
why is aquifer overuse a problem
an aquifer is a dynamic equilibrium so if outtake by humans is greater than recharge, the water in the aquifer will deplete.
what are the consequences of reduced supplies in an aquifer
water in aquifer depleting will cause the water table to drop, so will no longer be fully saturated with water. however the unsustainable use may not become obvious until after many years due to high volume of water storage, so human activities that relied may have to suddenly stop
how can we monitor aquifer water levels
GRACE satellites- orbit is affected by the force of gravity which is influenced by the mass of water in aquifers below their light path
what is subsidence
when excessive volumes of water are abstracted from an aquifer causing the ground to collapse under it’s own weight due to the ground not being supported by hydrostatic pressure
name 4 consequences of aquifer exploitation
subsidence (lower hydrostatic pressure so ground collapses under it’s own weight) / changes in surface hydrology / ecological impacts / saltwater incursion
what is the effect of changes in surface hydrology by aquifer overuse
springs supply wetlands and lakes, so if the water table is lowered spring flow will decline, water in wetlands may dry up
what is the effect of ecological impacts by aquifer overuse
if springs dry up plants with higher water requirements will die and be out competed, other species maybe affected because they relied on the water requirement plants eg food
what is the effect of saltwater incursion by aquifer overuse
salt-water moves into the aquifer in the spaces where freshwater has moved out and hasn’t recharged quick enough
what are the disadvantages of saltwater in aquifers
it’s expensive to turn to potable water, it’s no good for crop irrigation since it causes osmotic dehydration
how can u flush salt out of an aquifer
by artificial recharge, by pumping water down a pipe into the aquifer or allowing water to percolate down from special lagoons on the surface
name some advantages of artificial recharge
prevents subsidence and gives an opportunity to store excess water without evaporation losses,
how does flocculation work
flocculant is added, eg aluminium sulphate, where positively charged aluminium ions bind to negatively charged clay particles, resulting in electrically-neutral aggregate of clay and Al ions - floc. the floc then settles in a clarification tank
name 2 ways of desalinating salty water
reverse osmosis and distillation
describe the processes of reverse osmosis
water is pumped under great pressure through a partially permeable membrane that allows water through but not salt
describe the processes of distillation
boil the water at a low pressure, so the boiling temp is reduced, so the water condenses and the salt is left behind and the fresh water can be collected
name 4 factors that cause demand for water to change
change in population size / change in living standards / industrialisation / changes in attitude to water use
why does a larger population size change the demand for water
a larger population needs more water - population increase may be from birth rate > death rate or migration
why does a change in living standards change the demand for water
as piped water becomes available, people becoming increasingly affluent and buy more items that require water eg dishwasher / washing machine
how does industrialisation change the demand for water
companies have different water requirements eg irrigation. different types of farming uses water in different efficiencies eg subsistence agriculture relies on naturally available water. as affluence and technology become more available, irrigation could increase. chemical and steel industries use lots of water
how does changes in attitudes to water effect the demand for water
people have been encouraged by the government to be more careful with how they collect and use their water
how does overexploitation of water affect poorer countries
the affluent industries reduce the amount of water left for poorer societies, lowering water table for wells or reducing river flow
state the 3 main ways we conserve water and manage supplies
more efficient use of water / increasing the availability of water / better distribution of water
how does more efficient use of water help conserve and manage water supplies
by getting the same result with lower input. use water more efficiently eg metering (careful with ur water if you’re charged if u use a certain amount) / low water use systems (dual flush or hippo bag) / grey water use (water used in showering or washing clothes isn’t very dirty, so is reused for flushing toilets or watering plants
how does increasing availability of water help conserve and manage water supplies
catchment management (can make available water supplies more usable, reservoirs maintain river water levels and prevention of pollution upstream, making purification easier) / rainwater catchment (useful for low quality uses eg. flushing toilets) / aquifer recharge (prevent evaporation of aquifer and pump water into the aquifer|)
how does better distribution of water help conserve and manage water supplies
fixing leaks in pipes and appliances (reduces water loss) / inter-basin transfer (bringing in water from other catchment areas via canals eg UK national water grid)
