2.2 How do human activities influence water supply and demand?
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Demographic•
Economic
Key Idea 2.2 How do human activities influence water supply and demand?
• Societies vary considerably in their demand for water. For a given pattern of usage, increases in population generate greater demand. As a society becomes more developed, demand for water also increases. It is common for both pressures on water supply to grow at the same time. Major problems can occur when national boundaries cut across drainage basins. Agreement has to be made between countries over amounts of extraction and the quality of water put back into the system for consumers downstream. A river may have adequate supplies for all consumers along its length, but if an upstream nation extracts too much and returns contaminated water to the system, disputes and conflict may arise.
• Population increase leads to greater demand. This may be because the population is growing by natural increase, or that people are migrating to a particular area, or both are taking place. There are areas where the numbers of people are causing severe pressure on supplies.
• Economic development causes very large increases in demand per person. Domestic demand goes up as washing machines and dishwashers use many times more water than manual cleaning. There is a greater awareness of personal hygiene and baths and showers are more frequent. If homes have gardens, water is used for keeping lawns green and flowers well watered. As industries grow, water for cooling and processing is needed. In agriculture there is more frequent irrigation and regulations on cleanliness mean more frequent washing. In semi-arid areas, agriculture can raise the salinity of water supplies. With economic development, lifestyles change; e.g. car ownership increases and there is greater demand for car washes. With development, more piped water is available, and consumers respond by finding new ways to use water.
The growth of demand and the stresses produced on water supply in south-east England are outlined in
http://www.environment-agency.gov.uk/commondata/acrobat/grid_1464452.pdf
Determine the impact of demographic change on water supply
The competition for declining water supplies in the Murray-Darling Basin in Australia are provided in
http://www.wac.ihe.nl/dialogue/Basin/Murray-Darling/documents/Murray-Darling%20Report.pdf
Identify the pressures on water supply from competing economic activities in the Murray-Darling Basin
Some water sources need to be shared between different countries, each with its own demands
http://www.sam.gov.tr/perceptions/Volume1/June-August1996/WATERISSUESBETWEENTURKEYSYRIAANDIRAQ.pdf
How might water usage between Turkey and Syria be resolved?