Transcript Aquifer Depletion & World Water Usage

Aquifer Depletion &
World Water Usage
A glance at the globe suggests an
inexhaustible supply of water.
• However, only
about 3% is
fresh water.
• Of that 3%,
 70% is locked
in glaciers
 29% is found
underground
in aquifers
 1% is found
in lakes,
rivers, &
streams
The World’s Water Supply
Source: http://www.purdue.edu/dp/envirosoft/groundwater/src/supply2.htm
Groundwater is . . .
• An important source of fresh water
(represents over 90% of the world's readily
available fresh water).
• Located in aquifers -- underground layers
of porous rock and soil.
• Result of rain water seeping into the
ground, eventually finding its way into
aquifers.
• This underground water moves very slowly
and may take a long time to recharge or
refill.
Groundwater
Source: http://ga.water.usgs.gov/edu/earthgwaquifer.html
People around the world use the earth’s supply
of liquid fresh water for various purposes.
• Agriculture (42%)
• Electricity
generation (39%)
• Homes/offices/hotels
(11%)
• Manufacturing and
mining (8%)
Global water use has changed over time. What does
this graph tell you about water withdrawal and
consumption since 1900?
Source: http://www.unep.org/vitalwater/15.htm. For more info and graphs see UNEP website.
• The demand for water is increasing
due to:
Population growth
Better technology making it easier
to access water
• But, the earth’s freshwater supply is
limited.
Water & Population
• The world’s
population is growing
at about 80 million
people a year.
• Therefore, an
additional 64 billion
cubic meters of water
need to be found each
year.
Better Technology
• People access groundwater through wells
either by hand or by diesel/electric pump.
• Diesel/electric pumps allow people to
access water much more easily than by
hand.
Aquifer Depletion
• As the demand for water increases, deeper
wells must be dug.
• Water from deeper below the earth’s surface is
more likely to be contaminated with naturally
occurring minerals, such as radium, because it
has been in contact with rock formations for
hundreds or thousands of years and minerals
have dissolved into the water.
• Since aquifers recharge slowly, wells will
eventually run dry.
Aquifer Depletion in
Waukesha, Wisconsin, USA,
and Sana’a, Yemen
Sana’a, the capital of Yemen, is located in
the Middle East, one of the most waterscarce regions of the world.
Waukesha is located near the Great Lakes,
an area with abundant water resources.
Both regions risk losing their
supply of fresh water as their
aquifers are depleted.
Waukesha & Water:
A Historical View
• Late 19th century, Waukesha was a resort town
known for the healing properties of its mineralrich water.
• Lake Michigan was polluted.
• Officials in Chicago and Milwaukee looked to
Waukesha as a water source.
• In one incident in 1892, the people of Waukesha
used pistols, pitchforks, and fire hoses to
protect their water supply from speculators.
Source: Barringer, F. (2005, August 12). Growth Stirs a Battle to Draw More Water From the Great Lakes. New York Times.
Waukesha Today
• Today, Waukesha is depleting its aquifer.
• Its population increased 4.4% between
2000 and 2005.
• Population of city of Waukesha = 67,658.
• Population increase has led to increased
demand for water.
Waukesha
• Deeper and deeper wells have been dug.
• The current water level is more than 600
feet below its original level.
• Deeper wells = greater contamination of
water.
• Radium content of Waukesha’s water is
more than double the acceptable level set
by the EPA in 2000.
• Radium exposure over a lifetime has been
linked to higher risk of cancer.
A Solution?
• One solution proposed by City of Waukesha
officials is to build a pipeline to access Lake
Michigan water.
• However, a water protection plan called
“Annex 2001,” bans new diversions of water
outside the Great Lakes natural basin.
• Waukesha is 5 miles outside the Great Lakes
basin. Therefore it cannot take water.
• In spite of Annex 2001, city officials hope
their proposal will be approved by U.S.
and Canadian officials.
• Supporters of this proposal state that the
amount of water Waukesha would take
would not stress the Great Lakes’ water
supply.
• Critics of Waukesha’s plan say that the
problem is not that the amount of water used
by Waukesha would damage the Great Lakes,
but that a precedent will be set.
• States in the West, desperate for water, (AZ,
NV, and CA) could look to Great Lakes as
potential water source.
• Another suggested solution for Waukesha’s
water supply issues is water conservation.
• A third proposed solution is to obtain water
from west of Waukesha which would cost twice
as much.
Waukesha Questions
• Which of these solutions do you think is
best? Why?
• Can you think of some other solutions?
Sana’a, Yemen
• Sana’a, the capital of Yemen, is located at 7223
feet (2200 meters) above sea level, on a plateau
surrounded by several mountains.
• The old part of the city has been inhabited for
more than 2500 years and was designated a
UNESCO World Heritage city.
• It is a generally dry place with low rainfall and
limited surface water (few rivers or streams).
• The main source of water in the region is
groundwater.
• Yemen has one of the highest population
growth rates in the world at 3.6% (in
comparison the U.S. has a population growth
rate of 0.91%).
• Sana’a, with a population of 1,747,627, is
growing at an even higher rate as people move
from the rural areas to the city.
• The population increase raises demand for
water for drinking and growing food.
• Yemen is one of the world’s poorest countries.
Sana’a Yemen
• 60% of the people work
as farmers.
• Agriculture in the
Sana’a basin area
accounts for 80% of
water demand.
• Cultivation of qat (a
tree that has leaves that
are chewed as a
stimulant in Yemen)
and grapes (a cash
crop) consume the
majority of the water.
Urban Farming, Sana’a, Yemen, Photo credit: FAO
Better Technology
Another reason for increase in water use
is change from traditional farming and
water management methods suitable for
the region to modern farming techniques
such as powerful water pumps which
allow people to withdraw much more
water.
Sana’a and Aquifer Depletion
• Sana’a’s aquifers are dropping at a rate
of about 20 feet per year.
• If this rate continues they will be depleted
by the end of decade.
• The groundwater is used in irrigated
agriculture, industry, and households.
Sana’a and Aquifer Depletion
Continued
• Due to low rainfall, the groundwater does
not recharge at a rate that can keep up
with current demand and is therefore a
(mostly) nonrenewable resource.
• In the Sana’a region farmers and the city
are competing for water.
Reasons for Overuse of
Groundwater
According to the United Nations
Environment Program (UNEP) and the
World Health Organization(WHO), the
reasons for overuse of groundwater are:
– Unclear water rights and thus unregulated
extraction;
– Fuel subsidies and low import duties on
agricultural equipment;
– High returns on cash crops;
– Inefficient irrigation practices.
Response to Crisis By Government
• The Yemeni government has
– prohibited the drilling of new wells without a
permit
– prohibited the establishment of new
industries that consume large amounts of
water.
• However, this has not been enough to
stop depletion of the city’s aquifers.
Other Possible Solutions
• Some other suggested solutions are to
bring water from somewhere else, such as
coastal desalination plants, or to relocate
the capital.
• Some solutions suggested by
UNEP/WHO report were to reuse
wastewater in the city and to conserve
agricultural water.
Sana’a Questions
• Which of these solutions do you think is
best? Why?
• Can you think of some other solutions?
Questions for both Waukesha
and Sana’a
• What are the similarities and differences
between Waukesha and Sana’a?
• Do you think each city needs a different
solution? Why or why not?
• If you could create international water supply
guidelines that encouraged environmental,
social, and economic sustainability what would
they be?