WATER RESOURCESWATER RESOURCES

Water: we waste it, we pollute it, we take it for granted….

Virtually the most valuable commodity we have (along with O2 )

Tree = 60% water

Jelly fish = 90% water2

The water planet

atmospheric water

continental and sea ice

oceanslakes and rivers

O

Water

HH+

-

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All of the Earth's waters are circulated by the HYDROLOGIC CYCLEWater moves through the hydrologic cycle at various speeds.For example:

40,000 years to recycle oceanic water

2 weeks to recycle river water9 to 10 days to recycle atmospheric

waterWhere has your water been?4

The hydrological cycle

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Evaporation

• Injects water vapour into atmosphere• Uses 50% of energy at earths surface

(cools the earth’s surface)

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The Atmosphere

• only 0.001% of all water • links major water stores

– evaporation– condensation– precipitation

• cold air hold less water than hot air• as hot air rises and cools, precipitation

can form returning water to the earth or oceans

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Rain doesn’t always make it to the earth

P — precipitation

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EI—evaporation of intercepted rain

ET—transpiration

Interception loss may be 20 – 40% of total rainfall for forests

Rain doesn’t always make it to the earth

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Snow can turn into glaciers and remain on land a long time

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Antarctic ice photo by Megan Balks, Waikato Univ.11

Discovering Planet Earth

Rain that does make it to the earth can do several things…

infiltration

overland flow

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The majority of accessible fresh water is groundwater, water beneath the Earth's surface.

About 10% of precipitation will infiltrate the soil and rock to become groundwater, forming a water table.

Water saturated permeable rock is an aquifer.

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Aquifers

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Waimakirri River, New Zealand

Rivers return water from the land to the ocean

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The Water BalanceMay be applied to whole river

basins or catchments (watersheds)

SQEP Δ=++total evapotranspiration

catchment rainfall

river + groundwater discharge

change in soil or groundwater storage

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Quantifying the hydrological cycle

SQEP Δ=++

Rainfall to a watershed P = 15 mm Evapotranspiration E = -4 mmDischarge in stream Q = -6mm

Change in storage Q = + 5mm

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Rivers

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Boreal stream with organic acids flowing north to the arctic

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Most of earth’s water is in the oceans

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Water in the atmosphere helps trap heat

(H2O is a greenhouse gas)

and distribute heat

The hydrologic cycle is the main global energy redistribution system

-thru both the oceans and the atmosphere

Running the hydrological cycle takes energy!

Most of the energy for the hydrologic cycle comes from the sun

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Ocean currentsThe Atlantic Gulf stream carries energy at a vast rate from the gulf of Mexico to the Arctic Ocean: all the coal mined in the world in one year could supply energy at this rate for only 12 hours!

(Franks 1984)

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The hydrological cycle

2323

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Titan: methane cycle

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ONLY 0.01-0.03% of world’s water is readily available

AND this is NOT evenly distributed

(many water-poor countries in the middle east)

Human water use has increased 4-fold in the last 50 yrs!

increasing population and

increasing use per person

Approximately 70% of water used is for Agriculture 26

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- The BIGGEST water use

1950 -80 world irrigation area tripled

1990: 7% less irrigated area per person than 1980

increased competition between rural and urban water use

21% of USA crop irrigated by draw-down of water table

26% of world irrigated area suffers waterlogging and salinization

This is NOT SUSTAINABLE

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The Ogallala Aquifer

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Two main problems associated with groundwater usage:

Withdrawal can result in:depletion (removal of water from aquifers

faster than it can be replaced)land subsidencesalt water intrusion

Discharge can pollute groundwater (groundwater is very vulnerable to pollution which can be very costly and difficult to clean)

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Dams and Canals redistribute water

from areas of water surplus to water deficit areas

Dams are built to minimize flood damage, store water, or provide hydroelectric powerEnvironmental impacts of dams include: sediment accumulation, downstream scouring, water loss from evaporation, salinization, biological disturbance 32

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Used bySocietySubstitutions

Improved Efficiencies

Reuse and Recycle

ReduceRestoration

Remediation

Removal

Conservation(Input management)

Waste Reduction(Output management)

Resource Management

sources sinks34

CheapResource

EasyDisposal

High use bySociety

Water Resources

Environmental costs are typically excluded

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There are many areas where water is scarce!

Political and Economic solutions may be needed to effectively use our waterLaws now protect some surface and groundwater, but this is not true everywhereWater for agricultural use is subsidized--no incentive to conserve

McKinney and Schoch, 2003

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There are many ways to increase efficiency in our use

of waterMicroirrigation for agricultureIndividual lifestyle conservation

shorter showersdon’t let the water runlow-flush toilets

XeriscapingWastewater reclamation

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Water use

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WATER SAVINGS GUIDEWATER SAVINGS GUIDE

Activity:Conservative use- saves water

Normal use -- wastes water

ShowerWetdown/rinse off: 4 gallons

Regular shower: 25 gallons

Brushing teeth Wet brush, brief rinse: 1/2 gal.

Tap running: 10 gallons

Toilets Minimize flushing, low-flush toilets

Old toilet, frequent flushing?!?!

Leaks Report ASAP A small drip: 25 gallons per day

Energy Turn off power Wasting energy wastes water

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Key Points:

• Water circulates among the atmosphere, rivers, oceans, groundwater, glaciers and other

locations through the hydrological cycle• The hydrologic cycle is powered by the sun; it is a major way that global energy is redistribution

• Liquid Fresh water is a very small amount of the world’s total water supply (0.6% with only <0.03% readily available)

• Demand for fresh water is increasing, particularly for agriculture which uses most of the consumed water

• Water is not equally distributed throughout the world and conservation measures will become

increasingly important as water demand increases and conflicts for water use increase

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