FreshWater Uses
- Less than 1% of the world's water is readily available for direct human uses.
- These uses include agriculture and industry, drinking and domestic purposes, and energy generation and transport. Increasing competition for water among such uses is degrading the very natural resources on which we all depend.
- According to United Nations agencies, one-third of the world's population live in countries that are experiencing moderate to high water stress
- More than one billion people worldwide do not have access to clean freshwater. Three billion do not have adequate sanitation services and the annual death toll from water-borne diseases is estimated at more than three million.
- Floods and droughts claim lives and cripple economies.
- Flooding and drought, often brought on by poor management of river basins, claim thousands of lives and cause billions of dollars of damage to economies and communities. Dams and river navigation works have dramatically altered the amount, timing, quality, sediment content and temperature of flows in most major rivers, wreaking havoc on their natural functions.
- Pollution from towns and cities, industry and agriculture directly affect water supplies for people and freshwater ecosystems.
- The collapse of a tailing lagoon at a gold mine near Baia Mare in Romania washed 100,000 m3 of waste water containing cyanides and heavy metals into the Danube river basin, killing fish life and disrupting public water supplies.
- Diversion of water for agriculture and industry is destroying freshwater lakes and rivers
- In just 30 years, the Aral Sea - formerly the fourth largest lake in the world and a major fishery - has shrunk to less than half of its size, and has become as salty as the ocean. The diversion of irrigation water for agriculture and for power generation, led to severely reduced inflows, leaving an area of almost four million hectares of polluted soils and caused widespread economic losses and human suffering.
- Freshwater species are disappearing.
- Scientists generally acknowledge that species dependent on freshwater ecosystems are the world’s most endangered group of plants and animals. According to the WWF Living Planet Report 2006, 31% of freshwater species have disappeared between 1970 and 2003.
- Projections of trends into the future do not brighten the picture
- Currently, 54% of accessible runoff is appropriated by humans. By the year 2025, two-thirds of the world's population could be facing serious problems with water availability. Predictions regarding freshwater biodiversity impacts over that time-frame vary from the disastrous to the apocalyptic.
- Climate change is compounding these effects through increased frequency of extreme weather events.
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For Drinking
- About 70% of
the fat free mass of the human body is made of water. To function
properly, the body requires between one and seven liters of water per
day to avoid dehydration; the precise amount depends on the level of
activity, temperature, humidity, and other factors.
- Most of
this is ingested through foods or beverages other than drinking
straight water. It is not clear how much water intake is needed by
healthy people, though most experts agree that 8–10 glasses of water
(approximately 2 liters) daily is the minimum to maintain proper
hydration. For those who do not have kidney problems, it is rather
difficult to drink too much water, but (especially in warm humid
weather and while exercising) it is dangerous to drink too little.
- People can
drink far more water than necessary while exercising, however, putting
them at risk of water intoxication, which can be fatal. The "fact" that
a person should consume eight glasses of water per day cannot be traced
back to a scientific source. There are other myths such as the effect
of water on weight loss and constipation that have been dispelled.
For Weighing
- One liter
of water was used to determine the weight of a kilogram. Unfortunately,
the measurement of water was taken at one degree Celcius. Water is its
most dence at four degrees Celcius. Thus the measurement was actually
not correct.
As a Solvent
- Dissolving (or suspending) is used to wash everyday items such as the human body, clothes, floors, cars, food, and pets.
As a Thermal Transfer Agent
- Boiling,
steaming, and simmering are popular cooking methods that often require
immersing food in water or its gaseous state, steam.
- Water is
also used in industrial contexts as a coolant, and in almost all
power-stations as a coolant and to drive steam turbines to generate
electricity.
- In the nuclear industry, water can also be used as a neutron moderator.
Recreation
- Humans use
water for many recreational purposes, as well as for exercising and for
sports. Some of these include swimming, waterskiing, boating, fishing,
and diving. In addition, some sports, like ice hockey and ice skating,
are played on ice.
- Lakesides and beaches are popular places for people to go to relax and enjoy recreation.
- Many find the sound of flowing water to be calming, too.
- Some keep fish and other life in water tanks or ponds for show, fun, and companionship.
- Humans also
use water for snow sports i.e. skiing or snowboarding, which requires
the water to be frozen. People may also use water for play fighting
such as with snowballs, water guns or water balloons.
Industrial Applications
- Pressurized water is used in water blasting and water jet cutters.
- Also, very
high pressure water guns are used for precise cutting. It works very
well, is relatively safe, and is not harmful to the environment.
Food Processing
- Water plays
many critical roles within the field of food science. It is important
for a food scientist to understand the roles that water plays within
food processing to ensure the success of their products.
- Solutes
such as salts and sugars found in water affect the physical properties
of water. The boiling and freezing points of water is affected by
solutes. One mole of sucrose (sugar) raises the boiling point of water
by 0.52 °C, and one mole of salt raises the boiling point by 1.04 °C
while lowering the freezing point of water in a similar way. Solutes in
water also affect water activity which affects many chemical reactions
and the growth of microbes in food.
- Water
activity can be described as a ratio of the vapor pressure of water in
a solution to the vapor pressure of pure water. Solutes in water lower
water activity. This is important to know because most bacterial growth
ceases at low levels of water activity. Not only does microbial growth
affect the safety of food but also the preservation and shelf life of
food.
- Water
hardness is also a critical factor in food processing. It can
dramatically affect the quality of a product as well as playing a role
in sanitation. Water hardness is classified based on the amounts of
removable calcium carbonate salt it contains per gallon.
- Water
hardness is measured in grains; 0.064 g calcium carbonate is equivalent
to one grain of hardness. Water is classified as soft if it contains 1
to 4 grains, medium if it contains 5 to 10 grains and hard if it
contains 11 to 20 grains. The hardness of water may be altered or
treated by using a chemical ion exchange system. The hardness of water
also affects its pH balance which plays a critical role in food
processing. For example, hard water prevents successful production of
clear beverages.
- Water hardness also affects sanitation; with increasing hardness, there is a loss of effectiveness for its use as a sanitizer.
Power Generation
- Hydroelectricity
is electricity obtained from hydropower. Hydroelectric power comes from
water driving a water turbine connected to a generator.
Hydroelectricity is a low-cost, non-polluting, renewable energy source.
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