Socialess ultimo

sustainaility: if we use waer faster than it can be replenished, its use is not sustainable. we need to store and distribute it efficiently-and this can be expensive.

large-scale water management projects: large-scale projects to increase water supply tend to involve big dams. they are usually complex, multi-purpose projects. Up to the 1980s the rate of building increased, until most of the best sites in North America and Europe had been developed, in the so-called 'Blue Revoluion'.

Currently dams cupply: -40% of the world's irrigated water. -20% of the world's electicity. -and 15% os all blue water.

Drams may bring benefits in terms of increased water supply but they can have negative impacts too.Their construction plays havoc with fragile aquatic ecosystems, destorying fisheries and wildlife. Around 45000 large dams worldwide affect 6 out of 10 major rivers and have caused about 80 million people to be forcibly relocated.

SOCIAL advantage: scenit addet-recreational use, floods are controlled. ECONOMIC: advant: fish stocking, hydroelectric power attracts industry. disad: loss of farmland and villages, dam interferes with logging, navigation and fishing migration, less sediment means more energy, leading to ''clear water'' erosion. ENVIROMENTAL: ad: habitat for water birds, increase in humidity, water for domestic use and irrigation, regulated flow. dis: can reduce quality, sedimentation in lake, dam acts as a knickpoint-energy is reduced and deposition results,.

Pollution in developed economies: Developed countries have taken big steps to control pollution. Their economies are heavily based on tertiary and quaternary activities, which cause less water pollution than primary and secondary industries.

1960s, pollution caused major health problems and damaged acosystems. 1970s, government produced standards to improve water quality, and tackle pollution.

 small-scale solutions: non-governmental organisations (NGOs), often develop small-scale sustainable solutions to local problems in developing countries. Local communities are involved in projects to develop safe and reliable water supplies. NGOs set up low-cost projects using appropiate or intermediate technology. is appropriate to the geographical conditions of the local area, and within the technical ability of the local community so that they can operate and maintain it themselves. Local people are trained to take responsibility for the development and management of the schemes. The schemes include rainwater harvesting, protecting springs from contamination, developing gravity-fed piped schemes and building hand-dug or ube wells (are built where the water table is too deep to be reached by a hand-dug well) for villages.

Many of the NGO projects are in rural areal but others in urban areas. Help withsanitation problems, which will prevent water supply contamination.

Pollution in emerging and developing economies: levels of water pollution can be related to economic development. The highest levels of water pollution are usually linked to the most rapid rates of economic growth. These countries are industrialising and developing their energy sources rapidly. They tend to put economic growth before enviromental protection. Vey rapid urban growth, cities growing faster than the infrastructure fro piped water and waste disposal systems can be installed. Result, streams flowing through the slums and shanty towns of megacities are badly affected by pollution. Many countries also developing commercial agriculture. Runoff of chemicals increases water pollution. Developing countries generally lack the concentrations ofindustry found in more-developed countries. People live and work in rural areas. Pollution exists but it tends to be less concentrated.