EARTH SCIENCES - Notable Research and Discoveries Part 7 pdf

A United Nations UN report, “Water for People, Water for Life,” issued in nifi cant water shortages or other major problems in the next 50 years: 2003, predicts about half of the world’s

earth ScienceS

1

heating system, in which water from hot springs is piped into some of the city’s buildings

chemist and inventor Piero Ginori Conti (1865–

1939) builds the first electric generator running from geothermal power

energy to heat buildings

geothermal power station in the United States at The Geysers in California

The U.S DOE initiates a series of geothermal re-search projects in the Jemez Mountains of New Mexico and establishes a testing facility at Fenton Hill, New Mexico

Geothermal power stations appear in Hawaii, Ne-vada, and Utah

An interdisciplinary panel of scientists and engi-neers, organized by MIT, issues a report, The ture of Geothermal Energy, which recommends

Fu-investment in enhanced geothermal systems

Bruce D Green and R Gerald Nix of NREL, issue a

report proposing research on geothermal systems, based on the findings of a workshop in Golden, Colorado, on May 16, 2006

An Australian company Geodynamics, Ltd., com-tralia and begins development of a geothermal pow-

pletes drilling a well at Cooper Basin in South Aus-er station using hot fractured rock technology

California Energy Commission “Geothermal Energy.” Available

on-line URL: http://www.energyquest.ca.gov/story/chapter11.html

Accessed May 4, 2009 California generates more electricity from

Gibilisco, Stan Alternative Energy

Demystified New York: McGraw-Hill, 2007 In addition to explaining the concept of energy and

Geothermal Energy Technology.” News release, August 19, 2008

Geothermal energy—a Furnace beneath the Soil

Our Feet.” Available online URL: http://www1.eere.energy.gov/

geothermal/pdfs/40665.pdf Accessed May 4, 2009 This technical

Massachusetts Institute of Technology “The Future of Geothermal

Energy.” Available online URL:

http://geothermal.inel.gov/publi-cations/future_of_geothermal_energy.pdf Accessed May 4, 2009

Swissinfo.ch “Man-Made Tremor Shakes Basel.” December 9, 2006

Available online URL: http://www.swissinfo.org/eng/news/

United States Department of Energy “Geothermal Technologies

Program.” Available online URL: http://www1.eere.energy.gov/

1

aqueducts eventually served the city, the longest having a length of about 60 miles (37 km)

Freshwater continues to be a concern for cities today Humans need roughly a half gallon (1.9 L) of water a day to survive, and most people use a lot more than that for washing, sanitation, and other applications But according

to the World Health Organization (WHO), the number of people in

2002 who did not have access to safe drinking water exceeded 1 billion—about 17 percent of the world’s population—and thou-sands of people die every day from waterborne illnesses such as bacte-rial infections A growing popula-tion will put even more pressure on scarce water resources A United Nations (UN) report, “Water for People, Water for Life,” issued in

nifi cant water shortages or other major problems in the next 50 years:

2003, predicts about half of the world’s population will experience sig-

“Critical challenges lie ahead in coping with progressive water shortag-es and water pollution By the middle of this century, at worst 7 billion people in sixty countries will be water-scarce, at best 2 billion people in forty-eight countries.”

Although Americans generally have access to plenty of potable wa-ter, shortages caused by a drought can occur in various cities and states

In the 1930s, a severe drought struck the lower Midwest, parching the soil and resulting in the dust bowl, as the wind blew clouds of stifl ing dust throughout the region Because freshwater is essential to life, peo-ple in all countries should be aware of issues concerning shortages of clean, drinkable water One of the most important goals of Earth sci-ence is to understand the dynamics and distribution of this life-giving resource and to fi nd ways of alleviating present and future shortages

earth ScienceS

10

As geologists gain a more complete understanding of Earth and its water distribution, locating and exploiting water resources such as un-

of transportation Springs can also be an important source of water When

none of these sources suffice or they become too polluted, citizens must

turn to other strategies, as the Romans did when they built aqueducts

Rainfall in the United States for the first eight months of 2007—blue

and green indicate a higher than average rainfall whereas yellow and

orange indicate less than average The Midwest was more wet than

usual in this period (NASA image by Hal Pierce [SSAI/NASA GSFC])

earth ScienceS

1

Many people would like to control rainfall—for example, farmers whose crops need watering Although some engineers try to seed clouds

by dispersing tiny particles on which water can condense, this can only

(opposite page) Water molecules evaporate from the oceans and other

bodies of water and then fall as precipitation The cycle starts anew as

water drains into lakes, rivers, and seas.

Water Management—conserving an essential resource

earth ScienceS

1

Some cities draw at least a portion of their freshwater from nearby rivers or lakes Th e faucets of people in Philadelphia, Pennsylvania, for

instance, deliver fi ltered and treated water taken from the Schuylkill

aquifers—underground Water Sources

Water can fl ow underground, as it does aboveground, but not

nearly as fast since it must seep through soil or rocks except

in rare cases when a tunnel or cave is present Many

under-ground regions that have a lot of pores or crevices allow at least

some fl ow, so groundwater can seep into a well to replace some

of the water that has been pumped out But if water is pumped

out faster than it seeps in, the water level drops This drop may

be enhanced by a long dry spell, decreasing the amount of

avail-able groundwater Even if the water tavail-able is close to the surface

in the region of the well, not enough water can seep in fast

enough to replace the large quantity that has been pumped out

The well depresses the water table in the immediate vicinity, as

shown in the following fi gure, and can go dry.

Excessive pumping can also cause the surface around the well to collapse The reason for this collapse is the loss of water

in the pores and crevices, which creates empty spaces under

the ground As sediment falls into these spaces, the volume

decreases—the material is more compact—and the surface

becomes lower If the water loss opens up a signifi cant amount

of space, the material may not be able to support the weight of

the soil and rocks above The result is a sinkhole or fi ssure.

When too much groundwater is pumped from a larger area, such as around a large city, the land can subside—shift

downward Subsidence is a big problem in cities that pump

groundwater to satisfy a substantial portion of their water

needs In Mexico City, land subsidence caused by groundwater

withdrawal has resulted in warped roads and damaged

build-ings and has induced a slight lean in the beautiful Metropolitan

Cathedral.

River and the Delaware River Other communities rely on ground-water, which is pumped from wells For example, the majority of the

water supply in Mexico City, Mexico, comes from groundwater An

When users pump a well faster than nearby sources can replenish

it, the water level drops around the well, forming a cone in which the water table is depressed.

Water Management—conserving an essential resource

The United States fell on hard times in the 1930s after

the stock market crashed and the Great Depression

con-tracted the economy, leading to joblessness and poverty for

millions For the lower Midwest states, a second disaster

struck at the same time—the dust bowl A severe drought

beginning in 1931 parched millions of acres of land in Texas,

Oklahoma, Colorado, Kansas, and New Mexico The surface

turned to dust, and winds kicked up the dry soil into furious

dust storms that blanketed much of the region in dark, gritty

clouds People who got caught outside in these storms had

to grope their way home, even if they were close, since no

light could penetrate the murk Chickens came home for

the night—in the middle of the day On the PBS program

Surviving the Dust Bowl, which aired in 1998, an eyewitness

described the experience: “It kept getting darker and darker

And the old house is just a-vibrating like it was going to blow

away And I started trying to see my hand And I kept

bring-ing my hand up closer and closer and closer and closer And

I fi nally touched the end of my nose and I still couldn’t see my

hand That’s how black it was.”

Bad farming practices contributed to the problem In the years leading up to the 1930s, farmers had used the

people called Black Blizzard or Black Roller The term dust

bowl began to be used for the area after April 14, 1935,

known as Black Sunday, which featured a large number of dust storms.

The consequences of the dust bowl have been lasting People in the affected region suffered considerable health problems and economic hardships, and many people moved away The migration out of the dust bowl states was the largest mass movement of people in U.S history, with several million Okies loading up their trucks and heading for greener lands (Although only about 20 percent of these

long-migrants were from Oklahoma, the term Okie was

gener-ally applied.) Due in part to the depression, many migrants had trouble finding jobs, as dramatized in John Steinbeck’s

1939 novel, Grapes of Wrath One of the few beneficial

aspects of the disaster, though, was the development and implementation of improved farming practices A repeat of the dust bowl, even under severe drought conditions, is unlikely.

Water Management—conserving an essential resource

Animals like camels adapt to living in deserts and retain water in their

digestive tracts (Sean Randall/Stockphoto)

earth ScienceS

1

Information fed back to a crop irrigation controller permits greater efficiency, but researchers would also like to be able to predict specific

Values of the initial conditions are crucial, but there is always some uncertainty about these values because they come from measurements

To improve the accuracy of their models, hydrologists need to col-tion can influence distant events, the data needs to be global in scope

One of the best ways of gathering global data is from a position of great

altitude This requirement calls for a satellite

The National Aeronautics and Space Administration (NASA), the U.S government agency involved in space science and exploration,

launches many satellites to study Earth from space NASA’s Earth Ob-serving System consists of a series of satellites designed to keep an eye

on the planet, and one of these satellites, Aqua, is specifically designed

for hydrology (The term aqua is Latin for “water.”) Aqua, launched on

The image at left shows an Aqua satellite measurement of the

amount of reflected light (due mostly to clouds) over the United States and the Gulf of Mexico The image at right shows the amount of heat leaving the surface, with the red areas losing the most Energy flow

is critical to understanding the water cycle Note the hurricane in the

center of the images (CERES Science Team, NASA Langley Research

Center)

Water Management—conserving an essential resource

meet this need, the U.S government established the National Integrat-national Integrated drought

Information System (nIdIS)

Widespread droughts in 2006 included many of the Great

Plains states of the U.S Midwest, and in 2007 droughts in

the Great Plains as well as in the East cost more than $5

bil-lion in agricultural and other losses Severe water shortages

are not rare—at any given time, nearly a third of the United

States is affected For example, in August 2007, nearly 40

percent of the country suffered from moderate to severe

drought conditions (fortunately, the percentage dropped to

20 percent by May 2008) The West and Midwest—the old

dust bowl region—experience droughts frequently, but other

areas of the country are not immune.

Prompted by governors of western states and other

of-fi cials, the United States established the National Integrated

Drought Information System (NIDIS) in 2006 NIDIS is a

col-laboration of several government agencies, including the

De-partment of Agriculture, DeDe-partment of Commerce,

Depart-ment of the Interior, NASA, and others, led by NOAA The goal

is to collect and integrate data from these agencies—satellite

data, crop yields, water levels, and so forth—to assess and

monitor drought conditions and develop increasingly accurate

Since weather plays a strong role in drought conditions and local weather can be influenced by remote events, drought forecasts are necessarily global in scope For instance, an im- portant factor in drought occurrences in the United States is

El Niño, a periodic warming of the waters off the west coast of South America (The name of this phenomenon derives from the Spanish term for “the little boy,” a reference to Christ,

as the phenomenon is often observed around Christmas.) El Niño and its corresponding atmospheric oscillation are as- sociated with floods, storms, and droughts at a variety of locations around the world, which occur following particularly strong El Niño episodes Researchers have found that El Niño

is strongly linked to rainfall amounts along the coastal areas

of the United States and weakly linked to the central areas

of the country La Niña—a cooling of the waters off the west coast of South America—seems much more important to the situation in the central portion of the United States (La Niña

is Spanish for “the little girl.”) The nature of these links, and how they occur, are the subject of much ongoing research.

Water Management—conserving an essential resource