2.3 How can water supply and demand be managed sustainably?
New storage capacity.
Water transfers.
Groundwater sources.
Desalination.
Recycling.
Grey water.
Reducing consumptionKey Idea 2.3 How can water supply and demand be managed sustainably?
When demand for water is approaching the capacity of existing supplies, there are two responses that can help manage the situation. The most common is to explore ways to increase supply. The other way is to try to reduce demand, or more often and realistically, to slow down the rate at which demand is increasing. There are a range of ways of achieving each of these. In a particular area, not all the ways may be available.
The most common way of trying to increase supply is to build new storage capacity. This is not possible in areas of lowland with existing dense and widespread population. In places where it is possible it may lead to environmental damage, economic disruption and relocation of communities.
It may be possible to transfer water from an area where there is surplus to one where deficit may occur. Distance is an important factor here. Transfer is usually expensive to build. Whether it goes ahead is likely to depend on the funding a government has available, and to a lesser extent, on how critical it is to increase supply.
In areas where past development is limited, it may be possible to develop groundwater sources. In developed countries these are usually already fully utilised. Over use of groundwater resources can lead to contamination of the water underground. This is particularly the case in coastal areas where saltwater contamination is a threat.
A solution that is only available to rich economies that have access to the sea is desalination. It is hugely expensive and has very large demands for energy. The technology involved has scope for development. It is difficult to see how this method can be developed as countries are attempting to reduce their carbon emissions.
Recycling is a promising route and is already well developed in some places. Used water can be treated to remove contamination and bacteria and be put back into the supply. Water that cannot be restored to drinking quality can still be reused for washing, cleaning and cooling. In some areas there is resistance to using water that may recently have been flushed through a toilet.
In some areas, water falling on rooftops has been collected. This is amongst sources classed as grey water. Drinking water can be conserved, and this lower grade water used for purposes such as flushing toilets.
Reducing demand for water is not easy. Metering supplies and using price to induce restraint is one approach. Campaigns and generally raising awareness about wastage is another approach. If consumers do not reduce demand voluntarily, rationing may be considered by governments.How can Tucson manage its water supply and demand in a sustainable way? (Make sure you consider each of the bullet points from above).
CASE STUDY - Water Supply and demand in Tucson PowerPoint
Although new dams can be built, and storage greatly increased, their sustainability has been questioned
http://www.gisdevelopment.net/application/environment/water/ma04240.htmIdentify problems caused by the Three Gorges Dam
Transferring water from an area of surplus to one of deficit is possible
http://www.swpao.water.ca.gov/transfers/#PageTopAre water transfers sustainable?
Desalination has been suggested as a solution to water shortages, details from
http://assets.panda.org/downloads/desalinationreportjune2007.pdfHow feasible is it to obtain water supplies by desalination?
A brief introduction to greywater and recycling of water can be found at
http://www.deus.nsw.gov.au/Publications/greywater_reuse.pdfIdentify the benefits and problems of greywater
NEWater is an advanced recycling system described in
http://www.pub.gov.sg/NEWater_files/newater_tech/index.htmlHow acceptable is recycled water?
It is possible for consumers to reduce their demand, Anglian Water suggests
http://www.anglianwater.co.uk/index.phpsectionid=84&parentid=30&contentid=156How likely are consumers to reduce water usage voluntarily
Reducing demand by including cost and metering are considered in Australia
http://www.waterforlife.nsw.gov.au/__data/assets/pdf_file/0018/1458/06mwp_chapter_6.pdfIs it necessary for authorities to take measures to compel consumers to reduce water consumption?