Hydrosphere Flashcards
What are the three uses of water and how much does each use?
Agriculture- 70%
Industry- 22%
Domestic uses- 8%
How is water used in agriculture?
Irrigation
How is water used in industry?
Cooling, heating, washing and solvent
How is water used in domestic use?
Flushing toilets, washing clothes, dishes and hygiene
Why has the global demand for water increased?
Increasing population
Increase per-capita use with affluence
Increased irrigation of farmland
Industrialisation
What are the different reservoirs in the hydrological cycle?
Ocean, land ice, groundwater, lakes and rivers, soil moisture, atmosphere and living organisms
What is the quantity of water and resident time of oceans?
97%
Up to 4000 years
What is the quantity of water in land ice?
2%
What is the quantity of water in groundwater?
0.7%
What is the quantity of water in lakes and rivers?
0.01%
What is the quantity of water in soil moisture?
0.005%
What is the quantity of water in the atmosphere?
0.001%
What is the quantity of water in living organisms?
0.00004%
How are residence times calculated?
Volume of water in the reservoir divided by mean transfer rate
What are some human impacts on the hydrological cycle?
Deforestation, agriculture, urban development and global climate change
What is river channel discharge?
The total volume of water flowing through a channel at any given point
What human activities may affect precipitation?
GCC, abstract use, deforestation and afforestation
What human activities affect interception?
Vegetation- deforestation and afforestation
What human activities affect infiltration?
GCC, amount of soil
What human activities affect percolation?
Types of rock, GCC, heavy machinery
What human activities affect groundwater flow?
GCC, distribution of rain
What human activities affect runoff?
The surface (concrete)
What human activities affect evaporation?
GCC
What human activities affect transpiration?
GCC, deforestation and afforestation
What human activities affect river channel discharge?
Dams, GCC
What is the water table?
The boundary between ground saturated and unsaturated with water
What is a well?
A drilled hole to access an aquifer and pump/pipe water out, unwanted particles are filtered out (unconfined aquifer)
What is an Artisan well?
Doesn’t require a pump as the pressure in the confined aquifer forces the water out to the surface
What is porosity?
The volume of space available in a geological structure
What are 3 porous rocks?
Sandstone, shale and limestone
What is permeability?
The time taken for fluid to pass through a geological structure
What are 3 permeable rocks?
Sandstone, limestone and chalk
What geological structures may be present in order to create an aquifer?
Impermeable rock underneath
Explain the trends in domestic water use in the UK?
Increased overall- population and affluence
Increase SE England- population density for work
Increased S and SW- population migration for retirement
Explain the trend in agricultural water use in the UK?
Temperature rise means more irrigation is needed
Explain the trends in industrial use of water in the UK?
Decrease- more service industries
Decrease in NW England and S Wales- decline in heavy industry
What are the environmental effects of reservoirs?
Habitat change, wildlife barriers, river regime downstream of dams, sedimentation, microclimates
How do reservoirs affect habitat?
They destroy the previous, however they create wetlands, which are uncommon habitats and may be more valuable than the previous ones
How do reservoirs create wildlife barriers?
Barriers to wildlife that migrate along the rivers such as salmon and sturgeon, this is important for recolonisation of vacant areas
How do reservoirs affect river regime?
Regulate it by holding back in times of surplus and releasing when theres low amounts
What do changes in river flow affect?
Change river erosion and sedimentation and the development of meanders
Why are periods of low river flow important?
Some species, such as river turtles, need this time to lay their eggs on sandbanks
Why are periods of rapid river flow important?
Wash away sediments from gravel river beds for trout and salmon to lay their eggs
How is sedimentation in rivers affected by reservoirs?
Settle in the reservoir and not be carried downstream, they may have been important in fertilising flood plains downstream, counteracting erosion and building coastlines
How are microclimates affect by reservoirs?
Th large body of water may change the local climate due to high heat capacity of water temperature fluctuations are reduced, higher wind speeds, greater evaporation
How does most aquifer recharge occur?
Precipitation
When were some confined aquifers last recharged?
The previous ice age 10-20,000 years ago when the global climate was wetter
What are the dangers of ancient aquifer water in agriculture?
Often saline and can cause soil salinisation as irrigation water evaporates, leaving the salt behind, causing dehydration in plants
What are the dangers in over-exploitation of aquifers?
Changes in surface hydrology, ecological impacts, salt water incursion, subsidence, reduced supplies
How might ecology be affect by over-exploited aquifers?
Lowering the water table may kill plants and wetlands draining can kill aquatic or semi-aquatic plants
How might surface hydrology be affected by over-exploited aquifers?
Over-exploitation of groundwater will no longer be able to feed rivers, lakes and marshes
How might salt water incursion occur from over-exploitation of aquifers?
In coastal areas as the water table is lowered below sea level, it will cause the water flow sideways, this salt water makes the aquifer water unsuitable for irrigation as osmotic dehydration may occur
How might subsidence be affected by over-exploitation of aquifers?
The removal of water removes support for the geological structure which will now compact due to the material above, causing serious damage to buildings and pipelines
How might reduction in supplies be problematic due to over-exploitation of aquifers?
Unsustainable use means activities that have relied on it for hundreds of years may have to suddenly stop
How do we monitor aquifer depletion?
Checking the levels of the water table, NASA operates two GRACE satellites
How do GRACE satellites work?
Their orbits is dependent on the gravity, which is altered by the mass of water in aquifers, the entire Earth is surveyed every 30 days
What does GRACE stand for?
Gravity recovery and climate experiment
What factors should be considered when looking for new sources of water?
Quantity, reliability, purity and location
Where is rainwater collection most important?
In places where the demand is greater than the supply (India), it can also help reduce flooding
What features affect the usefulness of a river?
Total annual water flow, flow fluctuations, level of natural contaminants, pollutant from human activities
What factors effect reservoirs site selection?
Topography, geology, catchment area, water supply, pollution risk, sedimentation, infrastructure and existing land use and land conflicts
How is reservoir site selection affected by topography?
The main cost is building a dam, ideal topography creates a narrow exit from a large deep basin
How is reservoir site selection affected by geology?
The rock beneath must be impermeable, without faults or seismic activity
How is reservoir site selection affected by catchment area?
Ability to provide water
What is catchment area?
The are of land over which rain will flow or through the ground and then into the river
How is reservoir site selection affected by pollution risk?
Land uses in the catchment area shouldn’t provide serious risk (toxic pollutants from industry and agriculture pesticides)
How is reservoir site selection affected by sedimentation?
Soil erosion can make the water turbid, resulting in sedimentation in the reservoir which will gradually decrease the volume the reservoir can hold
How is reservoir site selection affected by infrastructure?
Workers, building material, access routes and machinery are all needed to set up a reservoir, convenient sites must be chosen
How is reservoir site selection affected by existing land use and land use conflicts?
A loss:benefit analysis must be considered (protected conservation areas valued over agricultural land)
What is an estuary barrage?
A freshwater reservoir created by building a dam across an estuary where a river enters the sea
What are the problems with estuary barrages?
The disrupt inter-tidal habitats, create and obstacle for shipping and can be polluted by human activities anywhere in the rivers catchment area
What are the problems with desalination of sea water?
Energy-intensive and expensive
What are some methods to increase sustainability of water?
Artificial recharge of aquifers
River regulation reservoirs
Inter-basin transfers
Unexploited aquifers
Afforestation
Water conservation
Water treatment
How do we artificially recharge aquifers?
During periods of high rainfall, it can be pumped into the ground or diverted to lagoons where it can infiltrate the ground gradually, diversion of rivers
What are inter basin transfers?
The use of canals or pipe systems to transfer water from areas of surplus to area of shortage
How is afforestation a method of sustainable management of water?
Trees help to reduce soil erosion and reduce the rate of flow of rainwater into rivers, this reduces fluctuations which helps to reduce flooding
What are some methods of water conservation?
Low volume uses, recycling water, pollution control, reduced wastage
What methods reduce the water volume use?
Low-water appliances, xeriscaping, low-volume irrigation
What is xeriscaping?
Management of gardens, parks and urban spaces such as roadside verges and roundabouts by planting by planting them with species that are adapted to dry conditions so that less water is needed to water them
How does low-volume irrigation work?
Drip irrigation delivers water directly to the plants and reduces water loss from evaporation
What is ‘grey water’?
Water that has been used but is still quite clean, e.g. bath/shower water can be used for toilets or gardens
What are some examples of water pollution control?
Oil pollution control, sewage treatment, acid mine drainage, control of heavy metal waste, landfill leachate treatment and buffer strips next to rivers reduce fertiliser runoff
How much water is lost from leaking in the UK?
20%
How can we reduce waste water?
Repairs and good maintenance, water meters
What are the quality requirements for potable water and why?
No pathogens, acceptable levels of toxins and looks, smells and tastes good
Public health risks and consumer complaints
What are the quality requirements for spray irrigation water and why?
Low turbidity, low levels of toxins
Blockage of water pipes and contamination of food
What are the quality requirements for textile washing with soap and why?
Soft water (low calcium ions)
Scum forms on textiles
What are the quality requirements for power station condenser cooling water and why?
No gross solids
Pipe blockage
What are the quality requirements for industrial boiler water and why?
Mineral deposits would build up, reducing heat exchange and blocking pipes
What are the water treatment processes (in order)?
Sedimentation
Screens (grit)
Aeration
Flocculation and clarification
Filtration
Activated carbon filters
Sterilisation
pH control
Fluoridation
Ion exchange
What does sedimentation do in water treatment?
Water is allowed to remain still and suspended particles, such as silt, settle
What do grit screens do?
Metal grills or meshes remove any vegetation and litter such as plastics and paper
What does aeration do?
Bubbles of air or water sprays are used to aerate the water and ensure a high dissolved oxygen content, some toxic metals are removed by aeration as they are insoluble
What are the concerns with anaerobic water?
May contain hydrogen sulphide from the decay of organic matter, which makes the water smell of bad eggs
What does flocculation and clarification do?
Neutralise suspended particles by adding flocculants such as aluminium sulphate or polyelectrolytes, they are mixed quickly with the water then passed into the clarifier tank where the particles are allowed to settle
Why don’t clay particles settle during sedimentation in the lagoon?
Electrostatic charges on their surface cause them to repel each other
What does filtration do?
Plant filters remove remaining solids and bacteria, these often involve slow flow through layers of sand and gravel
What do activated carbon filters do?
Particles are used to remove organic chemicals such as pesticides which adsorb onto the carbon particles
How is water sterilised?
Addition of chlorine, ozone and UV exposure to sterilise the water and kill pathogens
When is chlorine not suitable for sterilisation?
If the water collected is from peaty sources as organic matter may be present which could react with the chlorine and produce toxic substances
How is water kept sterilised for longer?
The use of chloramine as it gradually breaks down to release the chlorine
Why is pH control necessary and what do they do?
The addition of chlorine may have made the water too acidic so crushed lime is added to neutralise the effects
Why is fluoridation necessary?
To improve the dental health of the general public
What is ion exchange in water treatment?
The removal of toxic ions (lead, arsenic and mercury) from water using ion exchange resins, it can also remove calcium and magnesium ions to produce soft water
How does ion exchange work?
Toxic ions adsorb onto the surface of polymers beads or particles of zeolite
How does reverse osmosis work?
Saline water is filtered at very high pressure through a partially permeable membrane of very small polyamide tubes, about 50% yield
What are the sources of energy that drive the hydrological cycle?
Solar insolation- evaporation of water
GPE- condenses into clouds
KE- precipitation
What is an aquifer?
A body of rock that holds water which is exploited as a resource from underground
What is primary porosity?
The pore spaces that are formed during deposits
What is secondary porosity?
Pore spaces that develop after deposition, including cavities and fractures that are formed
What is effective porosity?
Total porosity minus any cement, anything space contributes to fluid flow through the rock
What are factors affecting porosity?
Rock type, degree of sorting, amount of diagenesis, grain shape and packing of grains
What are three impermeable rocks?
Mudstone, granite and clay
What is an anticline shape?
A dip
What are the best features of an aquifer?
Porous permeable rock, impermeable rock underneath, an anticline shape, a recharge zone, spring, sustainable extraction
What are the benefits of aquifer water?
Plentiful, filtered, pathogen-free, no turbidity, inland
How does water naturally flow out of an aquifer?
Evaporation and transpiration
What are examples of over-exploited aquifers?
High Plains (USA)
North China Plain
Malta (island)
What are the consequences of over-exploitation of the North China Plain?
Used for agriculture (irrigation)
Water table drops 1meter per year
Less water available
What method have been used to increase sustainability of North China Plain?
Low pressure irrigation pipes
Low water requirement crops
Charge per water used
Afforestation
River diversion of 450km
What are the consequences of over-exploitation of the Malta aquifer?
Precipitation rate of 550mm/yr but 400mm evapotranspiration so 150mm available
Water table dropped and salt water incursion has occured
What methods have been used for public and agricultural water in Malta?
Public: desalination of seawater
Agriculture: sewage effluents
What are the consequences of over-exploitation of the High Plains aquifer (USA)?
Stretches over 450,000km2 in an agricultural region
Fossil water (confined)
Abstraction is greater than recharge
What is the cone of depression?
The cone shape created in the water table by wells exploiting aquifers
What is the potentiometric (piezometric) surface?
Imaginary plain where the water level would rise to if not trapped in a confined aquifer
What is groundwater?
Water beneath the surface of Earth, typically held in soil or rock spaces
What is topography?
Arrangement of natural and artificial features of an area
What is sedimentation?
The process of settling or being deposited as a sediment
What is an MEDC or LEDC?
More economically developed country
Less economically developed country
What are the significances of water?
Anomalous expansion on freezing
Aquatic habitat
Solvent for chemical reactions
High specific heat capacity- thermoregulation
Lubrication for movement
transport within organisms
Absorption of UV up to 40cm
What are some rocks that never form aquifers?
Granite, slate, basalt, clay and marble
What are some rocks that commonly form aquifers?
Sandstone, limestone, chalk and gravel
What is the purpose of aeration?
Removes any tastes and odours
How does solar energy drive the hydrological cycle?
Causes warming leading to evaporation
What are the likely consequences of over exploitation of an aquifer?
Subsidence, lowered water table, reduced support and reduced river flow
What’s the difference between freshwater and saltwater treatment?
Reverse osmosis needed (50% yield) or desalination (expensive)
What are some impermeable rocks?
Granite and clay
