Water Resources Water is important for several reasons. - PowerPoint Presentation

Slide1

Water Resources

Water is important for several reasons.

It keep us alive; most organisms are more than 70% water.

It sculpts the earth’s surface and moderates the climate.

Water removes and dilutes wastes and pollutants

Slide2

Importance of

Water

Click on hyperlink to view video clip

The

unique properties of water are mostly due to the attractive forces between its molecules.

There are strong forces of attraction (hydrogen bonds) between molecules of water.

Attractive forces between water molecules cause its surface to contract and to adhere to and coat a solid. (cohesion and adhesion)

Slide3

Water exists as a liquid over a wide temperature range because of the strong forces of attraction between mater molecules.

Liquid water changes temperature slowly because it can store a large amount of heat without a large change in temperature. (high heat capacity)

Evaporating liquid water takes large amounts of energy because of the strong forces of attraction between its molecules.

Slide4

Liquid water can dissolve a variety of compounds.

Unlike most liquids, water expands when it freezes (this means that ice floats on water).

Water filters out wavelengths of the sun’s ultraviolet (UV) radiation that would harm some aquatic organisms

Slide5

Water resources video clip 2

Slide6

hydrologic cycle

Biogeochemical cycle that collects, purifies, and distributes the earth's fixed supply of water from the environment to living organisms and then back to the environment.

groundwater

Water that sinks into the soil and is stored in slowly flowing and slowly renewed underground reservoirs called aquifers; underground water in the zone of saturation, below the water table.aquifer Porous, water-saturated layers of sand, gravel, or bedrock that can yield an economically significant amount of water.

Infiltration the movement of water from the surface through the soil and into an aquifer

Hydrologic Cycle: Key Terms

Slide7

Hydrologic Cycle: Key Terms

floodplain

Flat valley floor next to a stream channel. For legal purposes, the term often applies to any low area that has the potential for flooding, including certain coastal areas.

watershed Land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river). recharge area Any area of land allowing water to pass through it and into an aquifer.natural recharge Natural replenishment of an aquifer by precipitation, which percolates downward through soil and rock.surface runoff Water flowing off the land into bodies of surface water reliable runoff Surface runoff of water that generally can be counted on as a stable source of water from year to year.

Slide8

Figure 15-2Page 307

Available Freshwater Supply

The management of water’s supply, renewal, and use is a huge twenty-first century challenge. Only about 0.01% of the earth’s supply of water is available as freshwater in the soil, in usable groundwater, water vapor, lakes and streams, but this supply is recycled.

The hydrologic cycle collects, purifies, recycles, and distributes the world’s freshwater supply.

The world’s demand for water now requires 54% of the world’s reliable runoff of surface water. We could be using 70–90% by 2025. In some places, usage rates are exceeding the reliable runoff available.

Slide9

Water Uses

Slide10

Water Use Activities

How much water do you use?

Water Loss Drop By Drop

Slide11

Slide12

The Unequal Distribution of Water

Slide13

Transfer of Heat Energy

Temperature

is the measure of the average speed of motion of the atoms, ions, or molecules in a substance or combination of substances at a given moment.

Heat

is the total kinetic energy of all the randomly moving atoms, ions, or molecules within a given substance, excluding the overall motion of the whole object. Heat always flows spontaneously from a hot sample of matter to a colder sample of matter. This is one way to state the second law of thermodynamics.Bill Nye -Heat

Convection

Heating water in the bottom of a pan causes some of the water to vaporize into bubbles. Because they are lighter than the surrounding water, they rise. Water then sinks from the top to replace the rising bubbles. This up and down movement (convection) eventually heats all of the water.

Slide14

Heat from a stove burner causes

atoms or molecules in the pan’s

bottom to vibrate faster. The vibrating atoms or molecules then collide with nearby atoms or molecules, causing them to vibrate faster. Eventually, molecules or atoms in the pan’s handle are vibrating so fast it becomes too hot to touch.

ConductionRadiation

As the water boils, heat from the hot stove burner and pan radiate into the surrounding air, even though air conducts very little heat.

Slide15

Global Air Circulation and Transferring Heat

Slide16

Water’s (Oceans) Role in Transferring Heat

Ocean Currents

Slide17

Following Water’s Journey – The Thermohaline Conveyor

Slide18

North Carolina River Basins

Click on the Map….it will take you to an interactive website exploring North Carolina River Basins

Slide19

Figure 15-7

Page 310

Highly likely conflict potential

Substantial conflict potential

Moderate conflict potential

Unmet rural water needs

Wash.

Oregon

Idaho

Nevada

California

Utah

Montana

Wyoming

Colo.

N.M.

N.D.

S.D.

Neb.

Kansas

Oak.

Texas

Water hot spot areas in 17 western states that by 2025 could be faced with intense conflicts and “water wars” over competition for scarce water for urban growth, irrigation, recreation and wildlife.

Water Issues in the United States

Slide20

Colorado River Basin / California’s Demand For Water

The Colorado River is 1,400 miles long and has been altered by 14 major dams and reservoirs to the point that water rarely reaches the Gulf of California now. This endangers many species that spawn in the river system and has led to increased salt contamination of aquifers near the coast.

Water demand in the desert

Slide21

Dam Impact

Dams vs. Salmon – Pacific Northwest

Slide22

Large losses

of water through

evaporation

Flooded land

destroys forestsor cropland anddisplaces peopleDownstreamflooding is reducedDownstream

cropland andestuaries aredeprived ofnutrient-rich silt

Reservoir is

useful for

recreation

and fishing

Can produce

cheap electricity

(hydropower)

Migration and

spawning of

some fish are

disrupted

Provides water

for year-round

irrigation of

cropland

Figure 15-9 Page 313

Dam Trade-offs

advantages

disadvantages

Slide23

The Everglades –

The River of Grass

An Ecosystem Dying of Thirst

Much of the everglades have been drained for agriculture and urban development

Slide24

Salton Sea and the Aral Sea Disaster

Aral Sea

Slide25

Groundwater

Overdrafts:

High

Moderate

Minor or none

Figure 15-16 Page 320

Groundwater

Slide26

Ogallala Aquifer

Slide27

Figure 15-8Page 311

Stress on world water supply

Increasing numbers of people relying on limited runoff produces a low per capita availability of water, which leads to

water

stress.

Water stress comes when the volume of reliable runoff per capita drops to below 60,000 cubic feet/year.

Water scarcity

occurs when per capita water availability falls below 35,000 cubic feet per year.

Slide28

Poor people live in hydrological poverty—they have no access and/or cannot afford clean water at a reasonable cost.

Freshwater supply can be increased by building dams to store water for later use, importing water from elsewhere, using groundwater, and utilizing desalination processes.

People in developed countries live near water supplies, but people in developing countries must make do with what is available.

Most people believe that everyone has a right to clean water.

Too Little WaterSolutions:Dams

Desalinization projects Groundwater decontaminationCloud seeding

New technology: Z-weed

Slide29

Most water resources are owned by governments and managed as publicly owned resources, but a number of governments are hiring private companies to manage them.

There have been mixed results, and the lesson learned is that governments need to maintain strict oversight of these contracts.

Two possible problems with a totally privatized water system are:

Private companies have an incentive to use as much water as possible rather than conserve it

The poor will continue to be left out because they can’t pay for the water.Water Politics

Slide30

Using Dams and Reservoirs to

Supply More Water

Dams and reservoirs capture and store runoff water. There are an estimated 800,000 dams that restrict the flow of rivers worldwide.

The water is released to control floods, generate electricity, and irrigate lands.

Reservoirs also provide for swimming, fishing, and boating.But dam and reservoir construction displaces people and floods productive land. The ecological services that rivers provide are given no value when building dams/reservoirs.A series of dams on a river in an arid area can disrupt the hydrologic cycle, since the water may not reach the sea that it previously supplied with water.About 60% of the world’s major river basins are strongly or moderately fragmented and disturbed. At least 24% of the world’s freshwater fish species are threatened or endangered

Slide31

Three Gorges Dam

1.2 miles long 610 feet high

A reservoir 385 miles long the size of Lake Superior

Slide32

Aswan Dam - Egypt

Slide33

Itaipu Dam

Slide34

Slide35

Gravity Flow

(efficiency 60% and 80% with surge valves)

Water usually comes from an

aqueduct system or a nearby river.

Drip Irrigation(efficiency 90-95%)Above- or below-ground pipes or tubes deliver water to individual plant roots.Center Pivot(efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler)

Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Irrigation Methods

Slide36

Conserving water

Composting toilets

Cisterns & rain barrels

Slide37

Floodplain

Levee

Flood

wall

Dam

Reservoir

Too Much Water

New Orleans (2005)– After Katrina

Missouri Flood 1993

Efforts to reduce flooding risk include:

Channelization – straighten and deepen streams

Building levees or flood walls

Buildings dams

(another dam project)

Slide38

Clearing of forests in the Himalayas and clearing mangrove swamps on the coasts has increased flooding in Bangladesh.

Great floods used to occur about every 50 years or so, but since the 1970s, they now occur about every 4 years.

Cutting of forests in the Himalayan foothills increased runoff and carried away vital topsoil.

Floods and cyclones have destroyed many crops and have killed thousands of people and left many others homeless.

Poor families have cleared many mangrove swamps for fuelwood, farming, and aquaculture ponds for raising shrimp, which ultimately led to greater flooding with the loss of those wetlands.Bangladesh: Living on the floodplains –Danger for the poor

Flooding – video clip

Slide39

Deforestation’s Impact on the hydrologic cycle and aquatic ecosystems

Erosion from deforestation - Madagascar

Slide40