freshwater resources 2006

Freshwater Resources

Ms. Mills

November 8, 2006

Water Supply and Demand

5 ways that people use water are:

1. household purposes

2. industry

3. transportation

4. agriculture

5. recreation


Household purposes Flush toilet, wash hands, take shower/bath,

drinking, cooking, washing clothes, cleaning, and the list can go on and on


Agriculture Irrigation – the process of supplying water to

areas of land to make them suitable for growing crops.

In the United States, more water is used for irrigation than for any other single purpose.


The practice of using less of a resource so that it will not be used up is Conservation.

Three ways to conserve water are to: Recycle Reuse Reduce


Two possible methods of obtaining freshwater in the future are:

Desalination Melting Icebergs

Desalination = the process of removing salt from water

Water to Drink

Water quality = measurement of the substances in water other than water molecules

Concentration = the amount of one substance in a certain volume of another substance

pH – measure of how acidic or basic a substance is

pH scale goes from 0 to 14 Pure water is neutral at 7.0; acid <7, bases >7

Water to Drink

4 Things that can Affect the Quality of Water are: Acidity Disease-Causing Organisms Chemicals Hardness

Hardness – the combined levels of two minerals, calcium and magnesium, in a sample of water

Hard water has higher levels Why does this matter??

Hard water does not form suds as easily as softer water

Water to Drink

Drinking-Water Treatment Process has 7 steps

First Filtration – filtered through screens to remove large particles (trash, fish, leaves)

Coagulation – Alum is added to cause sticky globs known as flocs. Mud and bacteria stick to these flocs.

Settling Basins – Water and flocs move onto a settling basin where the flocs settle out and sink to the bottom

Water to Drink

Drinking-Water Treatment ContSecond Filtration – water is then filtered through

sand and gravel which can filter out some bacteria and chemicals

Chlorination – chlorine is added to kill remaining organisms

Aeration – Air is forced through the water which releases gases and rids it of unpleasant odors and tastes

Additional Treatment –fluoride, sodium, lime or other chemicals may be added to treat H2O

Water to Drink

Treating WastewaterWastewater and the different kinds of

wastes in it is known as sewage.Two ways that communities deal with

wastewater are : septic systems and wastewater treatment plants.

Septic tank – an underground tank containing bacteria that treats wastewater as it passes through

Water to Drink

Water to Drink

Septic systems Inlet pipe from houseBacteria in pipe begins to break down

wastes denser wastes settle to the bottom = sludgeLess dense wastes float to top = scumOutlet pipe to leach field – water and broken

down wastes go to leach field where they finish breaking down

Water to Drink

Wastewater Treatment Plants Preliminary Treatment – removes large trash Primary Treatment – Water moves into settling

tanks where trash settles out (sludge) Secondary Treatment – Water is filtered through

gravel, where bacteria on the gravel break down wastes.

Additional Treatment – Water is pumped into open pools where sunlight and air help purify it; chlorine may be added. Some water will rejoin the water cycle through evaporation.

Freshwater PollutionFreshwater Pollution

Water Pollution – the addition of any Water Pollution – the addition of any substance that has a negative effect substance that has a negative effect on water or the living things that on water or the living things that depend on it.depend on it.

Substances that cause water Substances that cause water pollution are called pollution are called pollutantspollutants..


Sources of pollution are classified by Sources of pollution are classified by how they enter a body of water.how they enter a body of water.

Two ways:Two ways:– Directly enter (point source)Directly enter (point source)

Can be traced to a specific sourceCan be traced to a specific source

– Indirectly (non-point source)Indirectly (non-point source) Widely spread and can’t be tied to a specific Widely spread and can’t be tied to a specific

source of originsource of origin


Pesticide- chemical intended to kill Pesticide- chemical intended to kill insects or other organisms that insects or other organisms that damage crops.damage crops.– DDTDDT


Three major sources of water Three major sources of water pollution are:pollution are:– Human wastesHuman wastes– Industrial wastesIndustrial wastes– Chemical runoffChemical runoff

Freshwater PollutionFreshwater Pollution Human wastesHuman wastes

– Sewage from citiesSewage from cities– Sewage from rural areasSewage from rural areas

Industrial WastesIndustrial Wastes– Smoke and exhaustSmoke and exhaust– ChemicalsChemicals

Smoke and exhaust in the air (nitrogen oxide and Smoke and exhaust in the air (nitrogen oxide and sulfur dioxide) can react with water in the sulfur dioxide) can react with water in the atmosphere and lead to atmosphere and lead to acid rain.acid rain.

Acid rain is any rain or another precipitation that is Acid rain is any rain or another precipitation that is more acidic than normal.more acidic than normal.

– Heat PollutionHeat Pollution


Chemical RunoffChemical Runoff– Runoff from farmsRunoff from farms– Runoff from roadsRunoff from roads


There are two parts to the water There are two parts to the water pollution solution.pollution solution.– Cleaning up old problems Cleaning up old problems – Preventing new ones from occurringPreventing new ones from occurring

Droughts and FloodsDroughts and Floods

When an area experiences a long period of When an area experiences a long period of scarce rainfall, it is known as a drought.scarce rainfall, it is known as a drought. Caused by dry weather systems that remain in one Caused by dry weather systems that remain in one

place for weeks or months at a timeplace for weeks or months at a time Can cause crop failure or even famineCan cause crop failure or even famine In times of drought, people should conserve waterIn times of drought, people should conserve water


The most dangerous weather-related events in The most dangerous weather-related events in the United States are floods!the United States are floods!

Flash floods –sudden, violent flood that occurs Flash floods –sudden, violent flood that occurs within a few hours, or even minutes of a within a few hours, or even minutes of a storm.storm.

Usually due to large amounts of rainUsually due to large amounts of rain May be caused by a dam breakingMay be caused by a dam breaking


Flood PrecautionsFlood Precautions Advance warnings help reduce flood damage and loss of Advance warnings help reduce flood damage and loss of

life. life. Building dams are one method of flood control.Building dams are one method of flood control.

A dam is a barrier across a river that may redirect the flow of a A dam is a barrier across a river that may redirect the flow of a river to other channels.river to other channels.

Natural defense against floodingNatural defense against flooding Sediment (particles of rock and soil that are picked are build up Sediment (particles of rock and soil that are picked are build up

and are carried along by forces)and are carried along by forces) Sediments can build up and form Sediments can build up and form Levees (long ridges of sediment Levees (long ridges of sediment

that naturally help keep rivers within their banks, can be reinforced that naturally help keep rivers within their banks, can be reinforced with stone, sandbags and concrete)with stone, sandbags and concrete)

Water Power

EnergyKinetic energy – the form of energy that an object

has when it is movingPotential Energy – energy that is stored and waiting

to be used

Water and EnergyHydroelectric power – Electricity produced by the

kinetic energy of water moving over a waterfall or through a dam.

Hydroelectric power plants capture the kinetic energy of moving water and change it into electrical energy

Water Power

Hydroelectric Power Plants can have advantages and disadvantages.

Advantages:Clean, safe, efficientWater is freerenewed by the water cycle

DisadvantagesFlooding the land behind the dam can destroy wildlife habitatsDams form a barrier and prevent fish from traveling to other

parts of the riverExpensive to build dam

Water Power

Initially, water has potential energy (sitting still in reservoir behind dam).Flows through penstocks (changes to kinetic energy)Turbine begins to turn (mechanical energy)Generator with magnet is turned on (electrical energy)

Water Power

Freshwater Resources

Have fun studying!!!!!!

freshwater resources 2006

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