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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that each of its molecules contains one oxygen and two hydrogen atoms that are connected by covalent bonds. Strictly speaking, water refers to the liquid state of a substance that prevails at standard ambient temperature and pressure; but it often refers also to its solid state (ice) or its gaseous state (steam or water vapor). It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, and atmospheric humidity.
 
 
Water covers 71% of the Earth's surface.[1] It is vital for all known forms of life. On Earth, 96.5% of the planet's crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, 0.001% in the air as vapor, clouds (formed of ice and liquid water suspended in air), and precipitation.[2][3] Only 2.5% of this water is freshwater, and 98.8% of that water is in ice (excepting ice in clouds) and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products.[2] A greater quantity of water is found in the earth's interior.[4]
 
 
Water on Earth moves continually through the water cycle of evaporation and transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea. Evaporation and transpiration contribute to the precipitation over land. Large amounts of water are also chemically combined or adsorbed in hydrated minerals.
 
 
Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation.[5] However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability.[6] A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.[7]
 
 
Water plays an important role in the world economy. Approximately 70% of the freshwater used by humans goes to agriculture.[8] Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities (such as oil and natural gas) and manufactured products is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of chemical substances; as such it is widely used in industrial processes, and in cooking and washing. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, and diving.
 
 
  
 
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Latest revision as of 12:41, 24 November 2017

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The Water Portal

Estuaries and coastal waters are among the most productive ecosystems on Earth.
Water is vital for all known forms of life. Covering 71% of the Earth's surface, it is found mostly in oceans and other large water bodies. 1.6% of the total mass of the Earth's water is below ground in aquifers and 0.001% is in the air as vapor, clouds, and precipitation (rain, snow and sleet).

The Earth's water moves constantly through a cycle of evaporation and transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Over land, evaporation and transpiration contribute to the precipitation over land - thus deforestation and other changes to land can have wide and long-lasting effects through their impact on the water cycle.

Some observers estimate that by 2025 more than half of the world population will be vulnerable to a lack of water. Appropriate water supply and water purification technologies can help.

Related portal: Greywater
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Selected page

The new and improved Marsh
AEF greywater. For our final project we rebuilt a greywater system at the CSA, Arcata Educational Farm. Greywater consists of all used water produced at a particular site, except for water coming from the toilet, which is known as blackwater. When building a greywater system you first separate the greywater from the blackwater and send the greywater through a separate treatment system. Ideally, after the greywater passes through the purification process it will then be able to be reused. Greywater systems are an appropriate use of technology for many reasons. Some of them being: they reduce the use of fresh water, there is less stress on existing more conventional septic tanks, it is a highly effective purification process, and there is less chemical and energy use required. In our case the majority of water used on the farm is to water vegetables, herbs, flowers and fruits, and the source of greywater comes from the outdoor kitchen, used by the farmers and volunteers to cook and wash vegetables or dishes.
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Things you can do

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External resources

Interwiki links
  • Akvopedia - focused on water technologies.
  • WaterWiki.net - a UN sponsored wiki - most of the content indexes the work of UN agencies.
Sites

Appropriate technology · Built environment · Business · Construction and materials · Culture and community · Design · Energy · Energy storage · Engineering for Sustainable Development · Food and agriculture · Government supported development programs · Governments and sustainability · Green living · Greywater · Health and safety · Heat exchangers · Hybrid power systems · ICT and Education · Information technology · Learning · Medical Devices · Net Impact · Permaculture · Photovoltaics · Projects · Rainwater harvesting · Renewable energy · Service learning · Solar · Solar thermal · Sustainability · Sustainable business · Sustainable city living · Sustainable energy storage · Sustainable farm energy alternatives · Transport · Water Agricultural