Increasing water security Flashcards
Water security
Water security is about a population having reliable and sustainable access to enough good quality water to meet everyone’s needs for industry, agriculture, personal health, and to maintain the ecosystem.
Water diversion and transfer
Water diversion involves changing the course of a river so it flows to a different area. For example, in the 1960s, rivers flowing into the Aral Sea were diverted to irrigate desert crops. As a result, the Aral Sea is now 10% of its original size.
Water transfer schemes involve moving water from areas of surplus to areas of shortage - this is normally done by pumping it through pipes, tunnels, canals and aqueducts. For example, most of Birmingham’s water supply comes from the Elan Valley in mid-Wales - a series of dams and reservoirs provide a continuous supply for the city.
Water Catchment
Water catchment means collecting water (e.g. rainfall) for use.
Rainwater harvesting is an example of a water catchment scheme. Instead of allowing rainwater to fall on the ground and soak into the soil, it is intercepted before it hits the ground and stored in tanks.
This allows people to quickly access water in areas of shortage, rather than having to extract it from groundwater or surface water supplies.
For example, in Bermuda there are no rivers or lakes, and groundwater is hard to access. To avoid water shortages, every house is built with a stepped roof that is designed to collect enough rainwater to meet the water needs of the people that live in it.
Water Storage
Water can be stored during times of surplus-this means there’s enough water during times of deficit.
2) For example, building a dam across a river valley traps water, creating a reservoir. The reservoir is filled during periods of extended rainfall, and the water is released during drier periods. This ensures a consistent flow of water in the river all year round. For example, the Avon Dam and Reservoir in Devon was constructed in the 1950s to ensure a regular water supply to South Devon.
3) Reservoirs can increase water security, but they can also flood agricultural land and drown settlements - their construction can therefore cause conflict.
Desalination
Desalination is the removal of salt from seawater so that it can be used as a water source. Seawater can be heated to evaporate it and then condensed to collect the freshwater. Alternatively, seawater can be passed through a series of membranes to remove the salt (this is called reverse osmosis).
Seawater is abundant in many areas that lack sufficient freshwater, so desalination can significantly increase water security. For example, Dubai is in an arid area with very limited freshwater resources, but it is on the coast of the Persian Gulf- as a result, it obtains 98.8% of its water through desalination.
However, a lot of energy is needed to desalinate water. This means that it is an expensive way of increasing water supply, and as most of the energy comes from fossil fuels, desalination may cause pollution and contribute to climate change. Desalination is also a less viable option of increasing water security in landlocked countries.
Domestic and business water consumption can be managed to reduce demand and help to conserve supplies. E.g.
Modern appliances such as water-efficient washing machines and dishwashers use less water.
People can have a water meter fitted these charge users for the exact amount of water they use, so they encourage people to use less water. In the UK, every new house built since 1990 has been fitted with a water meter.
Home-owners and water supply companies can fix leaks to minimise waste.
Agricultural water use can also be reduced. For example:
Farmers can install drip pipes that direct water to exactly where it’s needed, and collect storm water for irrigation.
Farmers can also change their practices, e.g. by watering crops early in the morning to reduce water loss through evapotranspiration, or by contour ploughing (ploughing across a slope) to reduce runoff.
Recycling water
Recycling water means treating used water to make it safe to reuse straight away (rather than returning it to a river or the sea).
Most recycled water is used for irrigation, industry, power plants and toilet flushing, though it can also be treated enough to make it safe to drink.
Recycling makes water supplies more sustainable because it helps people meet their water needs without extracting more water from rivers or from groundwater.
Greywater
Greywater’ is a type of recycled water - it’s mostly waste water from homes and businesses, e.g. from washing machines and showers. This water is relatively clean, so it can be used to water gardens, flush toilets, wash cars and irrigate farmland without being treated first. It’s not safe for washing hands or drinking though.
Using greywater can make water supplies more sustainable, especially when it is used by industries that have high water use, such as hotels and sports centres.
It also means that clean water isn’t treated unnecessarily, which helps conserve energy.
Groundwater Management
Groundwater can be managed to make sure its quantity and quality are conserved. For example.
The amount being extracted can be monitored to ensure it is not extracted faster than it is naturally replaced. Laws can be passed to prevent over-extraction.
Farmers can be encouraged to apply less artificial fertiliser and pesticides to farmland, and companies that leak or dump toxic waste can be fined this helps to reduce pollution of groundwater.
In places where groundwater has been overexploited, aquifers can be artificially recharged. For example:
Injection wells allow water to be piped back into depleted aquifers. Infiltration structures are water-filled basins, ponds or trenches, from which water infiltrates to the aquifer.
Virtual Water Trade
Virtual water is a term used to describe our water that has been used in the production of something, e.g. the water required to grow a tonne of lemons or produce a tonne of steel.
For example, Middle Eastern countries where water is scarce may choose to import foods with a high virtual water value from countries with more water. Similarly, they may choose not to grow crops with a high virtual water value for export, so more water is available for other purposes.
