Water Use and Management

Pressing Issues The number of people who rely on freshwater is increasing Shortage of clean, fresh water is one of the most demanding environmental problems More than 1 billion people lack access to a clean, reliable source of fresh water

Global Water Use 3 major uses for water Residential Agricultural Industrial Europe and North America have the highest percentage of industrial water use 80% of water use in Asia is for agriculture

Global Water Use

Residential Water Use Average person in the United States uses about 300L (80 gal) of water every day Half of water use is for activities inside the home: Drinking Cooking Washing Toilet flushing Remainder is used for outside of the house: Watering lawns Washing cars

Water Treatment In order for water to be used residentially, it must be potable Potable- safe to drink Removes the following from water: Poisonous elements  mercury, arsenic, lead Pathogens- organisms (bacteria, viruses, protozoa, parasitic worms) that cause illness Pathogens are found in water contaminated by sewage or animal feces

Water Treatment Method 1. First filtration- source water is filtered to remove large organisms and trash 2. Coagulation- alum is rapidly mixed into the water which causes bacteria and other impurities to stick together to form sticky globs called flocsflocs 3. Second filtration- layers of sand, gravel, and hard coal filter the remaining impurities

Water Treatment Method cont. 4. Chlorination- chlorine is added to prevent bacteria from growing in the water 5. Aeration- air is forced through the water to release unwanted gases (reduces odor) and improves taste 6. Additional treatment- certain compounds added depending on the area Fluoride  helps strengthen teeth Sodium compounds or lime  softens hard water

Water Treatment Method cont.

Industrial Water Use Accounts of 19% of water used in the world Used to manufacture goods, dispose of waste, and to generate power Also used to cool power plantscool power plants Water is pumped from a surface water source (river or lake)  carried through pipes in a cooling tower  once water cools plants it is pumped back to the original source Water is warmer than the original source when it’s returned but it is generally clean and can be used again

Agricultural Water Use Accounts for 67% of water used in the world Plants require a lot of water to grow High-pressure overhead sprinklers are the most common form of watering crops Inefficient because 80% of water evaporates before it reaches the roots

Agricultural Water Use cont. Irrigation- a method of providing plants with water from sources other than direct precipitation Earliest form involved flooding fields with water form a nearby river Some crops irrigated by shallow, water-filled ditches

Water Management Projects For thousands of years, humans have altered streams and rivers to make them more useful Aqueducts- huge canals that brought water from the mountains to the dry areas of France and Spain

Aqueducts

Water Management Goals Bring in water to make a dry area habitable  people prefer to live in areas where the natural distribution of surface water is insufficient Create a reservoir for recreation or drinking water Generate electric power

Water Diversion Projects All or part of a river can be diverted (redirected) into canals that carry water across great distances to supply dry regions with water Colorado River is diverted to provide drinking water for Arizona, Utah, and California Since so much of it is diverted for irrigation and drinking water, it often runs dry before it reaches Mexico and the Gulf of California

Dams and Reservoirs Dam- a structure built across a river to control the river’s flow Reservoir- an artificial lake that is formed behind a damn when the river flow is stopped Water from the reservoir can be used for flood control, drinking water, irrigation, recreation, and industry

Dams and Reservoirs cont. Dams are used to generate electrical energy Hydroelectric dams use power from flowing water to turn a turbine that generates electrical energy 20% of world’s electrical energy is generated by them Three Gorges Dam- famous hydroelectric dam on Yangtze River in China Three Gorges Dam

Dams and Reservoirs cont. Consequences of a dam: Thousands of people displaced  removed from their homes Destroy entire ecosystems Land below the dam can become less fertile and productive  sediment from the river builds up behind the dam Dam may burst

Water Conservation Ensures that everyone will have enough water at a reasonable price Water becomes more expensive as water sources become depleted

Conservation in Agriculture Main causes of water loss: Evaporation Seepage Runoff Drip irrigation systems- deliver small amounts of water directly to plant roots by using perforated tubing Water released at a controlled rate Can be managed by computer programs that coordinate watering times by using satellite data

Conservation in Industry Need to recycle cooling water and wastewater Can discharge used water in a nearby river so it can be recycled and used again Denver, Colorado  one of first cities to realize the value of conserving water in business Created programs to save city and businesses money

Conservation at Home Take shorter showers and avoid taking baths Install a low-flow shower head and toilet Install low-flow aerators in water faucets Wash only full loads in dishwasher and washing machine Water lawn sparingly or at night to avoid evaporation Xeriscaping- a landscape that requires minimal water use  more stones and sand with less grass

Solutions for the Future Desalination- the process of removing salt from salt water Used by costal communities that rely on the ocean Desalination plants heat salt water and collect the freshwater that evaporates Can be expensive Transport water from one location to another in plastic bags Take water from rivers in Alaska and transport it to California Take water from icebergs