Water Flashcards
(65 cards)
1
Q
Why is water becoming so scarce?
A
- low, variable rainfall and high evaporation rate, and climate change
- rapid population growth, increasing demand for supply
- economic growth, increase water for industrial use
2
Q
Why are dams so important?
A
They provide our water requirements
3
Q
what is the purpose of large storage dams and inter-basin transfer schemes?
A
For irrigation, domestic and industrial water supply and hydroelectric power
4
Q
Why is the Gariep dam important?
A
supply of water to drier parts of the vaal, fish and sundays river
5
Q
What are the negative impacts of dam?
A
- Large cost
- creates a reservoir , which disrupts functioning of river ecosystem
6
Q
How do dams effect environment?
A
- Natural habitats are flooded
- organic material limited
- Surface area of water is increased, rate of evaporation increased
- large quantities of methane gas are produced.
7
Q
what does reduced natural flooding prevent?
A
- flood water from bringing beneficial silt and nutrients to the crops
- silt in rivers being flushed out and washed down to beaches
8
Q
What are wetlands?
A
Areas where teresstrial and aquatic ecosystems come together
9
Q
What does a wetland consist of?
A
- water table,near the surface of the ground. Land with shallow water.
- areas be fresh water, forming vleis, bogs, pans, marshes, swamps and floodplains
10
Q
why are wetlands so impotant?
A
- purify the water, act as filters, removing pollutants and excess nutrients.
- act as sponges, storing water. Help to recharge underground aquifers when water released to downstream areas.
- prevent severe damage during floods. soak up excess water.
11
Q
What is causing wetland destruction?
A
- by need for development by humans e.g crop prodution,pastures etc.
- ‘reclaimed’ for industrial use, construction of airports, harbours, housing development
12
Q
What is the Ramsar Convention?
A
an international agreement for the conservation and wise use of wetlands and their resources
13
Q
what farming practices, results in the loss of protective vegetation and causes erosion?
A
- Overgrazing
- ploughing of marginal lands
- cultivation without protecting lands from excessive run off.
- allowing cattle to form paths, which soon form gullies.
14
Q
What is the cause for the loss of availability of water?
A
- excessive runoff
- sedimentation in storage dams when valuable topsoil is washed away from sediment in streams. reduces capacity in storage dams
15
Q
What are floods?
A
An overflow of a large amount of water over dry land.
16
Q
How are floods caused?
A
- heavy rains
- human interferences, impact on flooding.
17
Q
Why are floods important?
A
- provide water to irrigate crops
- replenish the soil in flood plains.
18
Q
What is a drought?
A
An extended period of months or years where water availability falls below requirements for a reigon.
19
Q
What happen in drought?
A
a region consistently receives below average rainfall
more severe by humans using more water than is available in particular.
20
Q
what are exotic plants?
A
specie growing in an area where they do not naturally grow.
21
Q
What is a plantation?
A
even-aged monoultures grown over a large area/
22
Q
What varieties does Plantations include?
A
- Crops such as tea, coffee, cotton, tobacco, sugar cane.
- Trees such as pine, eucalyptus and acacia are planted because of their:
- Fast growth
- tolerance of rich or degraded land
- potential to produce large volumes of timber for industrial use
23
Q
How do plantations affect water availability?
A
trees may reduce the amount of goundwater, lowering the water table because:
- deep root systems, which absorbs more water that natural vegetation
- Groundwater is drawn by the large number of leave transpiring
24
Q
What is groundwater?
A
Water found in pores, cavities and cracks in hard rocks and soil off aquifers
25
What factors cause plantations to deplete the water table?
- What species make up the plantations
- What type of vegetation is being replaced
- The properties of the soil
26
What is a water table?
topmost level of groundwater
27
What is an aquifer?
A layer of earth and rock that holds water
28
What is the main source of aquifers?
rainwater
29
How do boreholes affect aquifers?
- groundwater is reached through wells or pumped out through boreholes.
- water is abstracted and water table is lowered.
- Borehole yields then drop, wells begin to dry up, groundwater is depeleted.
- supply of water is reduced.
30
How is water wasted agriculturally?
- overwatering of high pressure sprinkler systems used
- Watering crops on sloping ground, result in run-off.
- using old or broken pipelines and fittings, causing leaks
31
How is water wasted through urban usage?
excess water for gardening, bathing.
- appliances used unnecessarily
- substandard cheap or damaged fittings in houses.
32
How using water affects the quality?
Human activities result in effulent (waste water) which contains pollutants (harmful substances). If effluent finds its way into streams and rivers,it pollutes the water.
33
How is water used for domestic purposes?
washing machines, dishwashers, baths, showers and toilets
34
What is the use of water in agriculture?
use large quantities of:
herbicides( to kill weeds) - toxic
pesticides(kill pests) - toxic
chemical fertilisers - replenish nutrients
35
What is leaching?
chemicals washed away when it rains.
contaminate ground -water, rivers, streams and lakes.
water contamination can effect humans,livestock and crops downstream
36
What is eutrophication
enhanced growth of algae due to too many nutrients, mainly phosphates and nitrates.
37
Where do nutrients of eutrophication come from?
- run-off/inorganic fertiliser
- natural run-off of nutrients from soil and weathering rocks
- run-off of manure
- waste fro abattoirs or feedlots
- discharge of deterents
- discharge of untreated sewage.
38
How nutrients cause eutrophication?
excessive growth of aquatic weeds and blue-green algae. forms thick, green scum on surface of area. known as 'agal bloom.'
39
What are the effect of eutrophication?
- bloom causes clear water to become cloudy so light cant penetrate, so plants below cant photosynthesise.so die, increase dead plant biomass
- some cyanobacteria produce toxins called cyanotoxins, very poisonous, may affect humans.
- increased vegetation may slow down water flow and movement of boats, decrease recreational value of water.
40
What is the biochemical oxygen demand test?
refers to the amount of oxygen that bacteria in water will consume in breaking down the waste.the less oxygen there is, more bacteria, greater amount of pollutants.
41
Where does waste from mining come from?
abandoned surface and underground mines, processing plants, water -disposal areas or ponds containing tailings
42
What are tailings
Waste remaining after ore has been processsed
43
What cause does mining have an increasein?
change inPH
salinity
metal content
sediment load
44
What is acid mine drainage?
- pyrite occurs in large quantities in different types of mineral deposits.
- when mineral deposits are exposed to oxygen and water,pyrite weathers and oxidises to form sulphuric acid (very acidic water)
45
What is pyrite?m
mineral composed of iron and sulphur
46
What is the function of operating mines?
pump acid drainage into reserviors, treated with limestone to lower levels of acididty.
47
What is neutralisation
The lowering of of acid levels
48
How do heavy metals become toxic?
not metabolised by the body.
49
What can heavy metal toxicity cause?
- damaged or reduced neurological functioning/
| - damage to blood compositon, lungs, kidneys , liver and other vital organs.
50
What are long -term exposures?
slowly progressing physical, muscular an neurological degeneration
similar to Parkinson's disease, Alzheimer's disease, muscular dystrophy and multiple sclerosis.
51
What is fracking?
an abbreviation for hydraulic fracturing.
exploits shale gas reserves locked in underground rock formations
52
What is the process of fracking?
drill millions of water, sand and chemicals at high pressure into underground rock to fracture it, creating cracks for gas to escape
53
What are the disadvantages of fracking?
- uses huge volumes of water
- affect quality of water in aquifers
- lifetime of shale gas limited to 5-8 years.
54
What are the advantages
needed source of energy, cleaner and cheaper than coal.
| job creation and an incentive for foreign investment
55
What is thermal pollution?
degradation of water quality by any process that change water temperature.
56
What causes water temp to change?
- Power plants use water as a coolant
- Iron and steel industries release heated water.
- urban run-off, warmer than water running of vegetated land
- Removing trees and tall plants, removes source of shade, water heat up.
- lack of aeration, cause water in lagoons to heat up.
57
What are the consequences of thermal pollution?
- increase in kinetic energy,increases the movement of oxygen molecules, lowering the amount of dissolved oxygen in the water. death of aquatic animals
- redistribution of organisms in the community.
- blue-green algae to bloom as warmer water encourages this.
58
What is water purification?
The process of removing undesirable chemicals and pathogens from raw water in water purification plants.
59
What is raw water?
Water that is drawn from a stream, lake, or dam that has not been treated.
60
What methods are used to purify raw water?
- Physical ( filtration and sedimentation)
- chemical ( flocculation and chlorination)
- electromagnetic radiation (UV radiation)
61
What is water recycling?
It is cleaning waste water to remove solids and impurities so that it can be re-used or discharged back into the water.
62
How does water recycling take place?
- waste water treatment plants
| - in a septic tank system
63
Why recycle water
- reduces the amount taken from natural resources.
- Decreases the amount of untreated discharge sent back into water supply.
- conserves water, sustainable amount can be provided to the public.
- requires far less energy.
- using grey water saves municipal water.
64
What is grey water?
Waste water generated from domestic activities that can be recycled on site for watering the garden.
65
After rain what happens to the water?
seep into the ground , recharging levels of ground water
| form surface run -off,replenishes streams and rivers
