water Flashcards
(61 cards)
WHY ARE WE FACING A GLOBAL WATER CRISIS? (4)
Because the demand for water has been doubling every 20 years
Water is being wasted and polluted
Water distribution is uneven, leading to droughts in some areas
Changing diets also increases demand for water because some people richer, and start to buy and eat more meat and dairy which needs to be produced
why is it likely hat the global water crisis will get worse
Due to an increase in population and global warming which leads to changing rainfall patterns and water evaporation, and due to more development, so the industrial sector, the demand for water increases.
what are the main methods of water supply (4)
dams and reservoirs
wells and boreholes
desalination
rainwater harvesting
what is a reservoir
an artificial lake made to store water temporarily.
what is a dam
a barrier that holds water back. Mainly used to save, manage and prevent flow of excess water into specific regions. (affect 60% of the world’s major river basins)
wells and boreholes
A means of tapping into various types of aquifers (water bearing rocks), gaining access to groundwater. They’re sunk into the water table.
A borehole is drilled by machine and has a small diameter, wells are larger in diameter and sunk by hand
what percentage of the world’s water comes from underground sources
28%
what is desalination
Desalination is the process of removing slt and other impurities from seawater to make it drinkable freshwater. (Either by heating and condensing, or filtering it. It needs a lot of energy (unsustainable because fossil fuels are burned in the process).
how many people worldwide rely on desalination
300 million people worldwide rely on it
what is rainwater harvesting
Process of collecting and storing rainwater from rooftops or other surfaces for later use. It’s then filtered and stored.
how many countries worldwide is rainwater harvesting used in
over 100 countries worldwide
WHY HAS GLOBAL DAM CONSTRUCTION DECLINED SINCE PEAK IN 1970s?
because most of the best sites for dams are already in use or such sites are strongly protected by environmental legislation and therefore off-limits for construction.
ADVANTAGES OF USING DAMS AND RESERVOIRS AS WATER SUPPLY METHOD
(5)
Reliable water supply-they store a large amount of water, which ensures a consistent and reliable supply for drinking, irrigation and industrial use. (especially during droughts or dry seasons)
Can also replicate it on smaller scales and is simple and easy extraction process
Flood control
Can be used for HEP
After initial investment, you don’t need to spend anymore money
DISADVANTAGES OF USING DAMS AND RESERVOIRS AS WATER SUPPLY METHOD
(8)
Environmental impact- the building of dams can lead to the flooding of large areas,
disrupting ecosystems,
displacing local communities as it uses up land
Reduced fertility on floodplains as alluvium doesn’t reach them
affecting wildlife habitats.
This can cause long-term environmental changes.
Expensive
Water is likely to be contaminated so needs to be purified and cleaned.
Water will also be warmer as its on surface
well is (deepness, how is it dug, how is water drawn up, and where is it most common)
WELL:
Shallow (20-30 metres)
Dug manually or with basic machinery
Water is drawn up by a bucket or hand pump
More common in agricultural and rural areas
borehole is (deepness, how is it dug, how is water drawn up, and where is it most common)
Deep (reach hundreds of metres)
Drilled using specialised equipments
Usually have mechanical pumps to extract water
Common in areas where groundwater is deep or in urban/industrial areas.
difference between well and borehole
Overall, wells are shallow, manually dug, and more common in agricultural areas while boreholes can reach hundreds of metres, are dug with specialised machinery and more common in industrial areas.
WHAT IS AN AQUIFER :
Underground layer of permeable rock, sand or gravel which allows the flow of groundwater
WHY ARE WELLS AND BOREHOLES GENERALLY THE MOST IMPORTANT WATER SUPPLY METHODS IN ARID AND SEMI-ARID CLIMATES?
because dry areas have limited water on the surface as it evaporates quickly and this is why underground water sources allow water to be available and not get evaporated. Also dry areas usually lack lakes and water sources meaning wells and boreholes allow water to be conserved at a smaller distance for everyday use.
advantages if wells and boreholes (5)
- Reliable water supply (especially in dry regions)
- Easy to construct
- Water is cleaner
- More water than in rivers
- Sustainable as its extracted slowly
DISADVANTAGES OF WELLS AND BOREHOLES
(2)
High cost because of expensive drilling equipment and skilled labour making installation expensive
Unsustainable if rate of extraction is faster than rate of replenishment
advantages of desalination (4)
Provides freshwater
Reliable because ocean won’t run out & doesn’t rely on specific weather conditions
Sustainable (reverse osmosis)
Cheap if its reverse osmosis
disadvantages of desalination (4)
High cost
Disposing of the salty product can harm marine ecosystem if not well managed
Needs a coastline
Need reverse osmosis technology for it to be sustainable and cheaper
WHERE WOULD DESALINATION BE USED
(example country & why)
UAE
lack of freshwater sources, it has limited natural freshwater resources, like rivers or lakes so relies heavily on desalination to meet water demands for drinking and agriculture
high water demand due to population growth + climate. There is rapid urbanisation, growing populations and hot, dry climates so demand for water is very high in that region, making desalination a necessary solution to supplement water supply.