Water Unsustainability - Am MIT spezialisierte KI-Forschung

Water Unsustainability

Jerald L. Schnoor

Abstrakt: Water is a vital renewable resource that is increasingly stressed by multiple and competing
demands from people, industry, and agriculture. When water becomes unavailable or unusable, life itself
cannot be sustained. Changes in supply and demand for water are driven by population growth, climate
ändern, and our energy and land use choices. Poverty frequently precludes the ability of many people to
respond and adapt to water insecurity. In diesem Aufsatz, we discuss the effects of these drivers on the diminution
of rivers, aquifers, glaciers, and the severe pollution that renders some water resources unusable. Während
technologies for water reuse, desalination, aquifer replenishment, and better water pricing are important
Lösungen, the recognition of water as a profoundly threatened resource and as a basic human right is
essential for providing sustainable water for future generations.

Water unsustainability is more easily understood

than water sustainability: you know when you do not
have it. When water is unavailable or when it is of
unusably poor quality, life itself is unsustainable.

So how do we de½ne water sustainability? De½ –
nitions usually involve the concept of long-term wa –
ter availability for all uses. Supplying water to peo-
ple for the duration of their lives is one de½nition,
but is limited by a rather ethnocentric point of view.
More broadly, we may de½ne water sustainability
as the continual supply of clean water for human uses and
for the use of all other living organisms. This de½nition
neither speci½es exactly how much water is needed,
nor does it require the unconstrained, in½nite avail –
ability of water. Eher, it refers to a suf½cient quan –
tity of pure water for the foreseeable future for all
biota, including humans.

Water is, schließlich, a renewable resource; aufrechterhalten-
ing its uses should be relatively easy. But in reality,
we can have too much water or too little water at
different times, and the water available may be of
too poor quality. Water availability is often con-
strained by natural processes associated with the hy –
drologic cycle and geologic setting, or by jurisdic-
tional boundaries of governmental authorities and

JERALD L. SCHNOOR is the Allen
S. Henry Chair in Engineering,
Professor of Civil and Environmen-
tal Engineering and Occupational
and Environmental Health, and Co –
director of the Center for Global
and Regional Environmental Re –
search at the University of Iowa. Er
is a member of the National Acad-
emy of Engineering, the winner of
the National Water Research Insti –
tute Clarke Prize for water sustain-
ability, and the author of Environ-
mental Modeling: Fate and Transport
of Pollutants in Water, Air, and Soil
(1996). He has published in such
journals as Science, The Bridge, Und
En vironmental Science and Technology.

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water law. Water supply is also constrained
by existing infrastructure to deliver avail-
able water. Our ability to ensure enough
clean water for human uses is strongly in –
fluenced by the cost of water delivery and
the price of and demand for water. Daher,
many factors and trends affect the avail-
ability of water in space and time.

O does not cross the bound-
Because H
2
aries of our atmosphere, either to or from
outer space, Earth has held the same quan –
tity of water for eons. Earth’s hydrologic
cy cle is driven by the sun, which evapo-
rates water from oceans, lakes, Und
streams, and causes vegetation to transpire
Wasser. Daher, water is in a continuous flux
from evaporation to precipitation, Ergebnis-
ing in the recycling, puri½cation, and re –
distribution of it. Jedoch, the quality of
water and the fraction of H2O in each water
Phase (gaseous, liquid, solid) at a given lo –
cation are subject to change.

Currently, more than 99 percent of all
water on Earth is unavailable for human
use because it is too saline (in the form of
seawater) or is frozen as glaciers, ice, oder
snow. With a stored volume of about two
million cubic miles, groundwater remains
the largest component of freshwater avail –
able for humans. Lakes and streams rep-
resent the next largest stores at approxi-
mately thirty thousand cubic miles.1 But
the volume of freshwater stored in glaciers
is diminishing as a warmer climate begins
to melt continental glaciers and the Green –
land and Antarctic ice sheets. Viele
changes in water quality and quantity are
driven by human activities–not nature.

There are ½ve “driving forces” of change

that threaten water sustainability:

1) Population growth (and migration
pat terns to megacities). According to Unit-
ed Nations projections, the global popu-
lation will expand from 7.1 billion to 9.2
billion by 2050, further diminishing the
quantity of water available per person.

Weiter, when millions of people migrate
to megacities, it concentrates the demand
and stresses local water supplies, wieder
resulting in less water available per capita.
Humans are also increasingly moving to
coastal cities where seawater is too saline
for drinking and desalinization is too ex –
pensive. As we pump freshwater aquifers
more fervently to supply water for increas –
ing population growth and urban devel-
opment, salinity can intrude from the sea
and despoil groundwater supplies.

2) Climate change (changing precipita-
tion patterns and drought). Due to our
shifting climate, dry areas are generally
becoming dryer and wet areas are becom –
ing wetter all around the world.2 In arid
Bereiche, the relatively small amount of soil
moisture evaporates quicker under hotter
Bedingungen, resulting in more frequent and
profound droughts. Umgekehrt, humid
areas are becoming wetter with more in –
tense precipitation events and floods: Die
warmer ocean evaporates more water, Und
a warmer atmosphere can hold more mois-
tur, increasing clouds and bolstering
global rainfall rates. Too little water and
too much water are twin juggernauts of cli –
mate change that result in water unsus-
tainability.3

3) Land use change (increasing agricul-
tur, irrigation, and urban sprawl). Food
and water are intimately connected. To
feed an expanding global population, Wir
employ increasingly intensive agriculture
on expanded acreages, requiring more
chem ical inputs and further diminishing
water quality. Runoff from agricultural
land delivers soil particles, fertilizers, Und
pesticides into streams. Fertilizer nutri-
ents, im Gegenzug, over-enrich coastal waters,
caus ing eutrophication, harmful algal
blooms, and hypoxia (low dissolved oxy-
gen), which impairs water quality for hu –
mans and aquatic ecosystems alike.

Urban sprawl–which causes greater im –
perviousness, heightens stormwater run –

Jerald L.
Schnoor

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144 (3) Sommer 2015

Water
Unsustain –
ability

off, and prevents in½ltration to recharge
aquifers–is shrinking groundwater sup-
plies. Groundwater supplies are also di –
minished by the burgeoning water with-
drawals demanded by expanding popula-
tions and global agriculture. Irrigation is
by far the largest water user in the world.
Its impact on aquifers and rivers is partic-
ularly acute because withdrawals are a
“con sumptive” use of water: the water is
mostly lost to evaporation. In cases in
which water is not entirely evaporated,
agricultural return flows allow some reuse
options, such as recharging aquifers
through percolation (spreading) ponds.
But often the return flows are of such poor
Qualität (laden with salt or toxic leachates)
that they are useless for groundwater re –
charge.

4) Energy choices (power production,
bio fuels, and unconventional extraction of
oil and gas). Our energy choices to satisfy
the needs of growing populations and de –
velopment are loaded with water reper-
Diskussionen. Zum Beispiel, electric power pro –
duction withdraws more water worldwide
than any other use except irrigation. Für-
tunately, the cooling water from electric
power plants can be returned to the re –
ceiving stream with less evaporative losses
than irrigation. But if the temperature of
the returned water is too hot, or if it con-
tains anticorrosion chemicals or chlorine
disinfectant, it may cause deleterious ef –
fects on downstream ecosystems and ½sh –
eries.

The so-called energy-water nexus de –
scribes this tension between developing
energy and water supplies. It is axiomatic
that one cannot have water without large
energy inputs, or energy without signi½ –
cant water impacts. Development of new
fossil fuels (natural gas, oil, and coal) may
impact the quality of nearby surface and
groundwater. Some energy development
options extract considerably more water
als andere. “Unconventional” oil includes

oil shales, oil sands, coal-to-liquids, gas-to-
liquids, and deep-drilled ocean oil. Con-
ventional oil drilling and processing uses
about 8–20 gal/mmbtu (gallons of water
per million btu of energy produced),
while unconventional development of oil
sands uses signi½cantly more: 27–68
gal/mmbtu according to Chesapeake
Energy.4 But the largest water user is irrigat –
ed corn used to produce ethanol biofuels,
requiring more than 2500 gal/mmbtu,
or roughly two hundred gallons of “virtu-
al” water required to produce every gal-
lon of ethanol fuel burned!5 That is in ad –
dition to the environmental impacts of fer –
tilizers, eroded soil, and pesticides required
for growing the feedstock.

“Unconventional” energy development
affects water quality to a much greater
extent than conventional drilling and pro –
Abschließen. A blowout of a deep-ocean well,
such as the BP Macondo Well at the Deep –
water Horizon platform in 2010, causes
an outright water-quality disaster. Approx –
imately two hundred million gallons of
crude oil spilled along the Gulf of Mexico
coast directly into a sensitive ½shery and
a substantial tourism industry. Oil sands,
another unconventional oil resource, Re –
quire steam to liberate bitumen (a tar-like
substance), resulting in discharge ponds
of petroleum-contaminated water that
both is harmful to wildlife and scars the
landscape. Deep directional drilling and
hydraulic fracturing for shale oil and gas
deposits, which requires three to seven
mil lion gallons of water per well, are still
other methods.6 In hydraulic fracturing
(pop ularly known as fracking), drillers in –
ject a highly pressurized water, sand, Und
chemical solution into shale formations
to fracture the rock and allow natural gas
to flow more freely to the surface. The wa –
ter solution, Jedoch, returns to the sur-
face as flowback and produces water with
extremely high salt concentrations and
trace contaminants (toxic metals and ra –

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dio nuclides). Usually such flowback and
produced waters are reinjected into deep
wells, far below any aquifers used for wa –
ter supply. Instead of deep-well injection,
some oil and gas companies are trying to
recycle this water for use in hydraulic frac –
turing at another well. But if it is left on
the surface, the flowback and produced
waters form ponds of exceedingly poor-
quality water that are dif½cult to treat to
an acceptable standard for discharge into
receiving waters. Bedauerlicherweise, some un –
scrupulous gas companies abandon these
ponds for others to clean-up or for nature
to absorb.

5) Armut (physical and economic water
scarcity). Water scarcity afflicts poor peo-
ple more gravely than those with resources
to respond or adapt. Poor communities
cannot migrate to a better location, pay
to import safe drinking water, treat con-
taminated water to meet safe drinking
stan dards, repair a dry well, or pump wa –
ter across great distances. Volunteer foun –
dations and nongovernmental organiza-
tionen (ngos) recognize this dire need and
seek collaborative solutions. Goal 7 of the
United Nations Millennium Development
Goals–“Ensuring Environmental Sustain –
ability”–seeks to reduce the proportion
of people without access to safe drinking
water by half between 2000 Und 2015.7
In der Tat, the achievement of the safe
drinking-water goal is a major success story
of the un program. Yet there remain eight
hundred million people in the world who
still do not have an adequate water supply;
clearly much work remains. Nor has the
re lated development goal of adequate san –
itation facilities (toilets and conveyance
of sewage) for the more than one billion
people in need been met. The United Na –
tions has adopted a post-2015 development
agenda, with “Water and Sanitation for
All” a stand-alone goal. Such a comprehen-
sive global effort is absolutely essential for
water sustainability.

All ½ve drivers are highly interrelated.
We cannot mitigate climate change with-
out making the energy choices needed to
transition out of the fossil fuel age. Wir
must use land and energy wisely to help
create jobs and raise people out of poverty.
We cannot solve water problems related
to urban sprawl without curbing popula-
tion growth and migration to megacities.
And we cannot ensure clean water for an
expanding population without a global
social agenda that builds strong commu-
nities and empowers them to meet future
Herausforderungen.

Water unsustainability is becoming in –

creasingly evident in impoverished coun-
versucht, megacities, and large-scale arid re –
gions. We see it in the water stress of the
Naher Osten, North Africa, and South Asia.
We see it in the investment of billions of
dollars for water reclamation plants in
Singapore and desalination plants in Tian-
jin, China, and San Diego, Kalifornien. Jeder
day, newspaper headlines attest to human
struggles of having too little or too much
Wasser. We see it when lakes become so
polluted that they can no longer be used
for drinking, and when coastal waters turn
into dead zones devoid of ½sh. We see it
when water is no longer available for irri-
gating immensely valuable food crops, Und
when major cities are frequently flooded
by storms. We see evidence in mudslides
and wild½res, in one-hundred-year floods
and ½ve-hundred-year droughts. Let us
now examine a few poignant examples of
water unsustainability that have become
all too familiar: rivers that no longer flow
to the sea, wells that run dry, the extinc-
tion of glaciers, the loss of critical ground –
water supplies, and economic water scarci-
ty throughout the world.

The Colorado River is born from snow –

melt in the Rocky Mountains of Colorado,
Wyoming, and Utah. It twists through Ne –

Jerald L.
Schnoor

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144 (3) Sommer 2015

Water
Unsustain –
ability

vada, Arizona, and California on its way to
a ½nal hurrah in Mexico, where it forms a
twenty-four-mile borderline with the
United States and travels seventy-½ve
miles through Baja, Mexiko, to discharge
in the Gulf of California. The last remnant
of freshwater flow is captured in Baja by
the Morelos Dam, whose waters irrigate
rich farmland in the Mexicali Valley.

But the Colorado River has experienced
a steady decline in discharge volume over
the past century; in most years since 1960,
it has not even reached the Gulf of Cali-
fornia. Dams, diversions, and irrigation
have caused most of the water loss, In –
cluding increasing withdrawals for an ex –
panding population of forty million peo-
ple living both inside and outside the Col-
orado River Basin. Millions of acres of
expanded agriculture and the irrigation
required to grow cash crops in the middle
of the desert consume most of the incom-
ing water.

Lake Mead is a main stem reservoir of
the Colorado River near Las Vegas. It is
the largest dammed water body in North
Amerika, though–as a victim of repeated
droughts and rising withdrawals–it has
not been full since 1983. It provides power
for more than one million people and rec –
reation for many more, but spreading the
Colorado River over a large desert area has
increased evaporative losses signi½cantly.
Seit 2000, the surface of Lake Mead is
down almost 130 Füße, leaving a “bathtub
ring” on the rocky catchment and di –
vulging where water was once stored. Cli-
mate change has exacerbated evaporation
from Lake Mead (and its upstream sister
Lake Powell) and has decreased flow from
the river upstream.

The Colorado River is not alone: Die
Indus River in Pakistan, the Yellow River
in China, the Murray River in Australia,
the Amu Darya River in Central Asia, Und
the Theertha River in India are just a few
watersheds that terminate before reach-

ing their destination. All are located in arid
regions where temperatures and evapora-
tion are increasing, and where excessive
withdrawals of water for people and agri-
culture combine to promote water unsus-
tainability.

Big Spring, Texas, doesn’t spring any-

mehr. The town lacks a big spring or even
adequate surface water. Its wells have run
dry and its residents face frequent drought
and water shortages. In 2014, nearby towns
Wichita Falls, Lubbock, and Amarillo, Tex –
als, declared a stage ½ve emergency for ex –
ceptional drought. It was the driest year
on record–even drier than the Dust Bowl.
Other towns in Kansas, Oklahoma, Und
Texas on the Ogallala Aquifer in the South –
ern High Plains of the United States have
recently experienced “game changing”
drought and overwithdrawals. That they
all lie on the largest aquifer in North Amer –
ica turns out to offer them no insurance
against drought. Although torrential rains
and flooding in May 2015 ½nally broke the
Texan drought, the need for innovative
technology and investment in new water
infrastructure had become clear to every-
eins.

Big Spring responded by building a $14
million treatment plant to treat waste-
water and recycle two million gallons di –
rectly to nearby towns for drinking water.
By June of 2014, the Wichita Falls water
treat ment plant followed suit and became
just the second facility in the United States
to practice direct potable reuse (dpr): Die
treatment of wastewater for direct reuse
in drinking-water treatment plants with-
out an environmental buffer. Texans never
thought they would drink treated domes-
tic sewage, but direct potable reuse is an
increasingly common solution for water-
short areas.

California had a near-record drought in
2008. That one broke, but the state has rou –
tinely been short of precipitation since

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2011. Jetzt, In 2015, about half the state is
in exceptional drought (the most severe
category) and virtually all of the state is
abnormally dry. Governor Jerry Brown put
mandatory restrictions on urban areas to
curb water use, Aber 80 percent of the wa –
ter in California is used by agriculture.
Farmers have volunteered to reduce their
consumption by 25 percent in an effort to
prevent steeper mandatory cuts later on.
In many parts of California, groundwater
is all that remains, but in areas like Kern
County near Bakers½eld, it has been
pumped-down by more than ½fty feet since
2011. Glücklicherweise, water is a renewable
resource and nature stores freshwater in
viele Orte: aquifers, lakes, soils, glaciers,
and snowpack. But in California, all are in
short supply. Snowpack levels in the Sierra
Nevada are less than 25 percent of normal
levels, and reservoirs contain only a frac-
tion of their capacity.

More broadly, the California drought is
emblematic of a global problem: wells are
simultaneously being depleted in Pakistan,
Indien, Sub-Saharan Africa, China, und das
Mediterranean region. Wells run dry
through the interplay of excessive with-
drawals for population growth, climate
ändern, agriculture, industry, and energy
Projekte. The combination of these drivers
with widespread poverty inevitably causes
water scarcity. Impoverished communities
suffering from water scarcity cannot recov-
er or adapt; they lack the “resiliency” to re –
spond to the disruption of their water sup –
ply. Water may be available in the new
mark et at a higher price, but many simply
cannot pay.

Land-based glaciers are melting world-

wide. And tropical glaciers are melting the
fastest. In mountain ranges near the equa-
tor, tropical glaciers are our canaries in
the coal mine, early warning agents of cli-
mate change. While it is true that glaciers
have been melting ever since the Little Ice

Alter (circa 1650 Zu 1730), the melt rate is
much faster now and has only accelerated
seit 1980. We are witnessing the demise
of low-elevation tropical glaciers within
our lifetime; it is not simply a climate
change story but an important water sup-
ply story for this generation and the next.
Lower-elevation tropical glaciers tend to
be smaller than high-mountain glaciers,
and they are more vulnerable to melting.
Loss of these glaciers means collapse of the
communities that depend on glacial melt
for water supply and irrigation of crops. In
the Andes Mountains of Colombia, Boli –
über, Peru, and Ecuador, glaciers below
17,700 feet are melting at the fastest rate
in three hundred years: a near 3 Prozent
loss per year. Since the 1970s, the glaciers
have lost an average of four-and-a-half
feet of ice thickness per year from a total
of about one hundred thirty feet.8 In two
or three decades, they will be history.

On the way to extinction, melting gla-
ciers provide a lifetime of service to peo-
ple below. When glaciers ½rst begin melt-
ing, melt-water rivers are bolstered and
flow-rates increase. But once enough ice
has melted, the river reaches a peak flow
and flow-rates begin to decline. The sea-
sonal timing of the melt may also vary,
providing little water in late summer and
fallen, stressing irrigation and drinking-wa –
ter supplies. At lower elevations, snowmelt
and precipitation also provide water for
riv ers, and researchers strive to unravel the
precise contribution of glacial melt to total
river discharge. “Glaciers provide about
15 percent of the La Paz water supply
throughout the year, increasing to about
27 percent during the dry season,” Alvaro
Soruco, an Andean researcher, has report-
Hrsg. A loss of 27 percent of stream discharge
can be devastating to growing populations
with increasing agricultural development.
In the Peruvian Andes, glaciers are melt –
ing so fast that this critical component of
stream flow is vanishing. The Santa River

Jerald L.
Schnoor

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144 (3) Sommer 2015

Water
Unsustain –
ability

flows northward along the base of the An –
des, the Cordillera Blanca, and then turns
west toward the seaport city of Chimbote.
Precipitation in the Andes has changed
little since 1970, but the coastal climate of
Peru is about 0.7 degrees Fahrenheit
warmer–enough of an increase to melt its
glaciers. Santa River has already passed
“peak discharge” from glacial melt, so fu –
ture streamflow is expected to decline.
Some river flow remains from local precip –
itation and groundwater inflow, but ex –
panding withdrawals for irrigation proj-
ects in the coastal desert are claiming an
ever-increasing share of this diminishing
resource. During the arid month of July,
on ly a trickle of water now makes its way
down the Santa River to Chimbote, und ein
declining portion of that is glacial melt.

Lake Tai (Taihu) in Eastern China is the

third largest lake in the nation. Near the
mouth of the Yangtze River and the city
of Wuxi, the lake has been celebrated for
its beauty for centuries. Yet industrializa-
tion, agricultural expansion, and popula-
tion growth have in recent years given Lake
Tai the dubious distinction as having
among the poorest lake-water quality in
die Welt. In 2007, a harmful algal bloom
of cyanobacteria (blue-green algae) choked
the lake and threatened the water supply
for over thirty million people. Since the
1990S, the Chinese government has taken a
variety of drastic measures to combat the
lake pollution, including closing dozens of
industrial plants, flushing the lake with
Yangtze River water, dredging contaminat-
ed sediments, and severely reducing the
use of agricultural fertilizers in the basin.
Authorities even controlled the price of
bottled water when the price sky-rocketed
due to exponential demand from a pan-
icked public. But none of these interven-
tions have been successful in restoring wa –
ter quality, and Lake Tai remains a poster
child of water unsustainability driven by

the forces of population, expanding agri-
Kultur, and rampant industrialization.

By the time it flows from the Himalayas
to the Bay of Bengal, the Ganges River in
India serves approximately four hundred
million people. But the Ganges is plagued
by proliferate sewage pollution capable of
contaminating whole river basins. Accord –
ing to the Indian government, of the eight
hundred million gallons of sewage dis-
charged daily along the Ganges River, nur
20 percent receives any treatment what-
soever.9 Yet every day two million people
still bathe in the sacred river, posing a
major risk for the spread of water-borne
diseases. The Ganges is overloved and ov –
er used: she provides water for drinking
and washing clothes, a receptacle for raw
sew age and solid waste, and a ½nal resting
place for the ashes (and partial remains)
of the thousands who are cremated on the
Ganges annually in religious rituals. Clear-
ly such practices render use of the river un –
sustainable, but huge investment in sew –
age treatment plants would be required to
restore the sacred Ganges and protect the
health of the Indian people who rely on it.
But it is not only underprivileged popu-
lations in developing countries who suffer
from poor water quality. Rich countries
have been polluting their water supplies
with agricultural runoff from high-input
agriculture and factory farms such as con –
centrated animal feeding operations. ich war
born and raised in Iowa, a prosperous state
with the most productive agriculture in the
Welt. Iowa rivers flow through immense-
ly rich agricultural land, but farm runoff
carries an insidious load of soil particles,
fertilizers, and pesticides far in excess of
what a healthy stream ecosystem requires.
Weiter, nitrate from fertilizers moves eas-
ily from soil to stream via tile-line drainage
Systeme. It is transported about eighteen
hundred miles down the Mississippi River
to the Gulf of Mexico, creating a coastal
“dead zone” of low dissolved oxygen. Das

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Gulf Hypoxia is one of the largest of more
than one hundred ½fty such hypoxic zones
auf der ganzen Welt.

Increased agricultural activity to grow
the feedstock to support a new biofuels in –
dustry also jeopardizes water sustainabil-
ity in the United States. Biofuels are meant
to provide energy security for developed
countries and a high-value export for
developing countries. But as an energy
Auswahl, biofuels are incredibly water in –
tensive. Increased land and irrigation is
required to grow the feedstock for biofuels
(Mais, canola, wheat, beets, and sugar cane
for bioethanol; soybeans, sunflowers, Und
palm oil for biodiesel). In arid locations,
large water withdrawals from aquifers are
needed to irrigate crops, and more water
is required at production facilities to pro-
duce the fuel. Fertilizers required to grow
the feedstock crops lead to excessive nu –
trient runoff, which despoils water quality.
Gleichzeitig, food prices may rise in
response to the higher demand for corn,
soybeans, wheat, and canola. In the United
States at present, 40 percent of the corn
crop (about thirty-six million acres of a to –
tal eighty-four million acres of corn crop)
is dedicated to the production of ethanol
biofuel. Cellulosic feedstock from perennial
crops like switchgrass, miscanthus, Und
hy brid willow, or from crop and wood resi –
dues, hold promise for a greener future.
Perennial crops do not require annual til –
lage and would reduce soil erosion; Sie
would also use less fertilizers, pesticides,
and irrigation water.

Physical water scarcity is de½ned as the

lack of available water for humans and
eco systems, commonly occurring in arid
Bereiche, during droughts, and where water
has been overallocated (causing unsustain –
able withdrawals). Economic water scarci-
ty, andererseits, is the lack of water
infrastructure necessary to deliver water to
Menschen. It is typical of impoverished com-

munities who cannot pay to access water
from distant locations or whose water re –
quires signi½cant treatment for drinking.
In individual families, it often falls to wom –
en and girls to ½nd water wherever they
can, including by traveling long distances
to collect from wells or streams. Solch
sources may be contaminated, Jedoch,
causing intestinal illness, especially in chil-
dren.

Physical water scarcity presumes invest –
ment in infrastructure to overcome short-
ages during times of drought and in regions
with progressively drier climates. Ov er –
allo cation of water resources is common
in California, where agriculture preceded
other forms of development and “prior ap –
propriation rights” dictate that farmers
now control the water. When surface allo –
cations are consumed during droughts,
ground water becomes the sole water sup-
ply and is quickly overdrawn. But the fre-
quency and intensity of the problem is
made direr by irrigation and by interbasin
transfers to growing cities that may have
purchased appropriative rights. The largest
such transfer in recent years is the massive
“south-to-north” interbasin transfer of
water from the Yangtze River in China to
northern megacities like Beijing and Tian-
jin. When the project is fully completed,
it will transfer 4 Zu 5 percent of the annu-
al flow of the Yangtze, the largest river in
China.

Interbasin transfers may be avoided
through water conservation and reuse, von
recycling industrial and municipal waste –
Wasser (sewage) and treating it to drinking-
water quality, and by practicing indirect
or direct potable reuse. Industry is also
contributing to water conservation by
designing new plants with “zero water
footprints” and by capturing the precipita-
tion that falls on their property (rainwater
harvesting) for treatment and recycling.
But all of these measures require “getting
the prices right” such that the cost of water

Jerald L.
Schnoor

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144 (3) Sommer 2015

Water
Unsustain –
ability

reflects its scarcity in a free market. Mit
higher prices, private and public water
com panies will develop the infrastructure
necessary to conserve and reuse water
and/or desalinate seawater and brackish
groundwater. The cost will also incentivize
citizens to learn to conserve water re –
sources, as Californians have tried to do.

One solution to water unsustainability

is to recycle treated wastewater for non-
potable uses (such as using purple pipes for
watering lawns and shrubs) or to practice
water reuse by recycling highly treated
wastewater for use as drinking water.
Water reuse is actually widely practiced
Heute, if inadvertently. By the time the
Trinity River in Texas flows from Dal-
las–Fort Worth to Houston, every drop
has passed through a wastewater treat-
ment plant. With drawals from the river
for drinking-water treatment and distri-
bution use treated domestic sewage
wheth er customers re alize it or not.
Because of vast im provements in waste-
water treatment prac tices, the Trinity
River is of surprisingly good quality and
still supports many aquatic species. Daher,
people already prac tice po table water
reuse in one of three forms: 1) inadver-
tent potable reuse (as in Trinity Riv er,
Texas); 2) indirect potable reuse (as in
Orange County, Kalifornien); Und 3) di rect
potable reuse (as in Big Spring and Wichi-
ta Falls, Texas).

Indirect potable reuse is the practice of
reusing highly treated effluent from do –
m estic or industrial wastewater and dis-
charging it into a reservoir or aquifer (ein
environmental buffer) for storage. After a
few months, the water is withdrawn and
treated for drinking-water distribution.
The environmental buffer tends to help
users overcome the “yuck factor” that
typically characterizes public opinion on
drinking highly treated sewage (direct po –
table reuse). In indirect potable reuse,

three factors are at play. Erste, the waters are
mixed (diluted) with existing water in the
reservoir or aquifer. Zweite, the treated
waste water is naturally ½ltered and pu –
ri½ed in the reservoir or aquifer for some
period of time. Endlich, after the water is
withdrawn it is treated once again to
drinking-water standards prior to distri-
bution.

There are only a few communities in the
world that presently practice direct po –
table reuse of drinking water. The ½rst use
of direct potable reuse was in Windhoek,
Namibia, In 1968, Wann 250,000 Menschen
began using highly treated wastewater for
drinking. Windhoek has practiced direct
po table reuse ever since with no reports
of illness or long-term negative effects. Big
Frühling, Texas, is the ½rst application of this
process in the United States, and its success
has led Wichita Falls, Texas, to follow suit.
One of the most urgent tasks for com-
munities facing water unsustainability is
to replenish their depleted aquifers. Sus-
tainable groundwater levels offer a mea –
sure of resiliency for the future akin to wa –
ter insurance. Full aquifers, reservoirs, Und
storage tanks all offer insurance in times
of need, but aquifers are immense
and–better than any other method of
storage–can protect and hold more wa –
ter with little loss to evaporation.

Aquifer storage and recovery (asr) Und
shallow aquifer recharge (sar) are two
meth ods practiced today in Oregon, Wash –
ington, Nevada, Kalifornien, Florida, Und
Tex as. Shallow aquifer recharge refers to
the percolation of water from a surface
pond to replenish a shallow aquifer,
though not necessarily for recovery and
drinking-water reuse. Full aquifers are de –
sirable themselves for the capacity to bol-
ster streams and to restore wetlands and
springs that may have drained.

California’s Orange County Water Dis-
trict Groundwater Replenishment System
(gwrs) is a leader in shallow aquifer re –

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charge. It recycles and treats wastewater
that would have otherwise been discharged
to the Paci½c Ocean. The wastewater is
treated to very high purity and exceeds
state and federal drinking-water require-
gen; but rather than be withdrawn for
drinking, the treated wastewater is natu-
rally ½ltered through sand and gravel per-
colation basins in Anaheim, Kalifornien.
There the replenished aquifer serves as the
source of drinking water for 2.4 Million
Menschen. The groundwater is subsequently
pumped-up, treated again, and distrib-
uted to nineteen municipal water agencies.
Aquifer storage and recovery describes
the process of using wells to pump water
into con½ned aquifers under pressure be –
low the water table (where the water pres –
sure head equals the atmospheric pres-
Sicher). These aquifers may often be brack-
ish or slightly salty, and the fresh, highly
treated wastewater forms a “bubble” on
top of the aquifer that can be accessed dur –
ing a drought or dry season as an emer-
gency water supply. The South Florida Wa –
ter Management District oversees the op –
eration of dozens of injection wells with
the capacity to recharge aquifers with wa –
ter of various qualities, including treated
and untreated groundwater, partially treat-
ed surface water, and reclaimed (highly
treated) wastewater.

In this essay we have seen that driving

forces of population growth, climate
ändern, urban and agricultural sprawl,
energy development, and global poverty
jeopardize future water supplies and ren-
der our present practices unsustainable.
Water unsustainability poses risk for this
and future generations. We should adapt to
these changing conditions and mitigate
them wherever and whenever we can. Ad –
ap tation takes the form of preparing for
climate change, creating and refurbishing
our water infrastructure, reusing water,
re charging aquifers, making wise energy

choices, and utilizing hyper-ef½cient irri-
gation for crops to feed the world. Mitiga –
tion requires transitioning from the fossil
fuel age and improving human prospects
through acts of global cooperation, as in
the United Nations Sustainable Develop-
ment Goals post-2015.

Many of the problems discussed herein
will not be solved solely through new tech –
nologies. Economic and social issues are
integrally linked to the problems of water
Nachhaltigkeit. Zum Beispiel, we will not
come to grips with economic water scarci-
ty without the determined efforts of all
stakeholders to eradicate poverty, improve
Ausbildung, and empower communities.

We are today experiencing a widespread
crisis of water unsustainability throughout
die Welt, with effects at the local, region-
al, and global scales. At the local scale, Die
drivers cause profound hurdles for indi-
viduals and families in gaining access to
safe drinking water. At the regional scale,
droughts and floods are increasingly fre-
quent, inflicting human misery on a bur-
geoning population, while ecosystems suf-
fer from poor water quality caused by our
energy and agricultural practices. At the
global scale, our efforts to reduce our
greenhouse gas emissions have been sty –
mied by competing economic and politi-
cal interests. It is likely we will come to
know the impacts of climate change
through the effects delivered upon our
most vulnerable and shifting water re –
sources. Unless we can overcome or adapt
to these driving forces, future generations
will inherit a legacy of declining and de –
graded water resources. Our relationship
with water and how we use it can evolve to
meet this challenge, but it requires an un –
derstanding of the drivers of unsustain-
ability and an acceptance of high-quality
water as a human right.

Jerald L.
Schnoor

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144 (3) Sommer 2015

Water
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ability

Endnoten
1 Franklin W. Schwartz and Hubao Zhang, Fundamentals of Ground Water (Hoboken, N.J.: John

Wiley & Sons, 2003).

2 Jerald L. Schnoor, “Living with a Changing Water Environment,” The Bridge 38 (3) (2008):

46–54.

3 Intergovernmental Panel on Climate Change, Climate Change 2013: The Physical Science Basis
(Working Group I Contribution to the Fifth Assessment Report), Hrsg. Thomas F. Stocker, Dahe Qin,
Gian-Kasper Plattner, Melinda M.B. Tignor, Simon K. Allen, Judith Boschung, Alexander
Nauels, Yu Xia, Vincent Bex, and Pauline M. Midgley (Cambridge; New York: Cambridge
Universitätsverlag, 2013).

4 Chesapeake Energy, Leading a Responsible Energy Future: 2013 Corporate Responsibility Report
(Oklahoma City: Chesapeake Energy, 2013), http://www.chk.com/documents/media/
publications/2013CorporateResponsibilityReport.pdf.

5 National Research Council of the National Academies, Water Implications of Biofuels Production

in den Vereinigten Staaten (Washington, D.C.: National Academies Press, 2008).

6 Cornell University City and Regional Planning, Hydraulic Fracturing–Effects on Water Quality
(CRP 5072) (Ithaca, N.Y.: Cornell University, 2010), http://www.cce.cornell.edu/Energy
ClimateChange/NaturalGasDev/Documents/City%20and%20Regional%20Planning%20
Student%20Papers/CRP5072_Water%20Quality%20Final%20Report.pdf.

7 United Nations, The Millennium Development Goals Report (New York: United Nations, 2013),

http://www.un.org/millenniumgoals/pdf/report-2013/mdg-report-2013-english.pdf.

8 Antoine Rabatel et al., “Review Article of the Current State of Glaciers in the Tropical Andes:
A Multi-Century Perspective on Glacier Evolution and Climate Change,” The Cryosphere Discus-
sionen 6 (2012): 2477–2536; and Antoine Rabatel et al., “Current State of Glaciers in the Tropical
Andes: A Multi-Century Perspective on Glacier Evolution and Climate Change,” The Cryosphere
7 (2013): 81–102.

9 Janak Rogers, “India’s Polluted Ganges River Threatens People’s Livelihoods,” Deutsche Welle,
November 21, 2013, http://www.dw.de/indias-polluted-ganges-river-threatens-peoples
-livelihoods/a-17237276.

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