Living with a Changing Water Environment
By Jerald L. Schnoor
Networks of volunteers working within a common framework to improve water quality can transcend geopolitics.
Water, like all things on planet Earth, is changing. But the changes in water resources are attributable primarily to human activities,
not natural causes. Four major factors profoundly affect access to
quality water: population growth and migration; climate change; changes
in land use and energy choices; and global poverty. The legacy of these
four factors will be not only less water but also more degraded
water, especially for poor people. Unless we find better ways to
protect and improve our water supplies, the future looks dire for
billions of people.
Our environment has changed dramatically, even in the past few decades,
and the effects are apparent at the local, regional, and even global
scale. Arguably, water is our most precious resource, yet we face
looming crises in the availability of water for humans, not to mention
for fisheries and all aquatic species. The American Society of Civil
Engineers estimates that U.S. water and wastewater infrastructure alone
will require an investment of $1 trillion over the next 20 years (ASCE,
2005).
What can we do to meet these challenges? First, we must recognize the causes of the problem and seek to mitigate them. Second, we must adapt or change by altering the way we treat and use water. Third, as engineers and scientists, we must provide appropriate, sustainable technology for water infrastructure. Fourth, we must find better ways of monitoring, modeling, and forecasting our water future to provide stakeholders and decision makers with better information.
Drivers of Change
Population Growth
Global population has been growing for 1,500 years, except for a brief
period in the 1300s when the bubonic plague was rampant (Figure 1).
However, it took thousands of years from the dawn of civilization for
the population to grow to 1 billion people, in about 1800 A.D. It took
only 125 years to reach 2 billion, and then 33 years to reach 3
billion. Since then, the population has grown by about a billion every
13 to 14 years.

FIGURE 1 Increase in world population from 500 A.D. through today and projected to 2150 with high, medium, and low
demographic assumptions. The medium projection reaches a peak population of nearly 10 billion people in 2075 and levels off at
8 to 9 billion. Projections are from mass collaboration at Wikipedia (http://upload.wikimedia.org/wikipedia/commons/7/79/
World-Population-500CE-2150.png) accessed on July 16, 2008.
The threat of water scarcity is directly related to population
density. When population densities are low, the threat of water
scarcity is also low. But when population densities are high, any
decrease in available water can be disastrous—not necessarily because
of a lack of water, but because we lack systems that ensure access and distribution
of precipitation and fresh water. Today, humans use approximately 54
percent of all of the available fresh water on Earth (Postel et al.,
1996). Considering the global trend toward growing populations and mass
migrations to coastal megacities, many of which are already semi-arid
and short of water, the future looks bleak.
The situation is unsustainable, even where adequate distribution
systems make inter-basin transfers of water possible; even then
increased migration and changing precipitation patterns make future
water allocations uncertain. For example, snowmelt water is allocated
and conveyed from the Sierra Nevadas (and a portion of the Colorado
River) to southern California, which is home to more than 20 million
people but only has enough precipitation to provide water for about 1
million people. Because of decreasing snowfalls in the Sierra Nevadas,
we have created a situation that precludes further growth in southern
California. In fact, even the current population is at risk in times of
drought.
Climate Change
In 2007, the United Nations Intergovernmental Panel on Climate Change
(IPCC) issued its fourth assessment, a consensus report based on work
by hundreds of scientists in dozens of countries (IPCC, 2007).
According to the IPCC, our climate is changing, primarily as a result
of emissions of greenhouse gases (GHGs) (i.e., human activities). The
temperature is already 0.76°C warmer than it was from 1850 to 1899
(Figure 2), and it is likely to increase by 2.0 to 4.5°C (with a best
estimate of about 3°C) during the 21st century. In addition, extreme
events, such as heat waves, droughts, and increased-precipitation
events (floods) will become more frequent.

FIGURE 2 Global temperature changes from 1880 to 2005. The annual average temperature (averaged for the entire planet
for all seasons) has increased about 0.8°C in the past 125 years. Source: Adapted from Hansen et al., 2007.
Increases in precipitation are very likely in high latitudes, while
decreases are likely to occur in most subtropical regions, continuing
recent trends. This means that regions like the southwestern United
States and Mexico, Central America, Brazil, southern Europe and the
Mediterranean, northern and southern Africa, the Middle East, and
western Australia will receive much less precipitation (10 to 30
percent less than they did from 1980 to 1999). Decreases in
precipitation in Africa, Latin America, and southern Asia already
threaten billions of poor people who can least afford to respond to the
challenges of a warmer, drier world.
We are already experiencing human-induced changes in climate. Arctic
ice, permafrost, and continental glaciers are melting rapidly. The
Ganges River, which supplies water to 450 million people and is fed by
glaciers, is destined for eventual decline. Stationarity, the
scientific term for when statistics are not changing and conditions are
constant, is a thing of the past (Milly et al., 2008). We can no longer
count on the mean precipitation or even on traditional annual
variability in precipitation.
In such a scenario, it is almost impossible to plan for the future.
Most climatologists are less concerned about the increase in mean
global temperature and precipitation than they are about the extremes
(heat waves, droughts, and floods). We must, somehow, make plans for
living in a world with rapidly changing water resources.
Changes in Land Use and Energy Choices
In an effort to develop systems in which citizens can prosper, we
convert land to agricultural and industrial uses that require large
amounts of water and, in the end, degrade water quality. Every year in
the tropics, countries such as Brazil, Malaysia, India, and Indonesia
clear huge tracts of forest for agricultural development. Every year in
the United States, almost a million acres of land are converted to
impervious cover, mostly highways, parking lots, and strip malls, which
increases runoff and decimates urban stream ecology. Development is
greatest in coastal counties where 53 percent of Americans now live.
In addition, because oil is in short supply and extremely expensive,
many countries, such as Brazil, countries in Europe, Malaysia, Japan,
China, and the United States, have adopted biofuels as a strategy for
reducing, or at least stabilizing, oil imports. “Energy security” and
“energy independence” have become the watchwords in these countries. In
the United States the emphasis is on ethanol production from corn. In
other countries, ethanol is produced from sugar cane and sugar beets,
and biodiesel is produced from canola, sunflower, palm, and soybean
oils.
However, biofuels are not sustainable, at least not in the way we
practice row-crop agriculture today. Far too many nutrients run off the
land causing eutrophication of nearby waters, and far too much soil
erodes for biofuels to be considered sustainable in the long run. We
need a crop system that is perennial, that minimizes (or eliminates)
tillage, and that holds soils and nutrients in place.
As Figure 3 shows, ethanol production in the United States depends on
intensive, high-input corn as feedstock. The intensive agriculture
necessary to supply this corn requires about 8 grams of nitrogen (as N)
fertilizer and results in 10 to 20 kilograms of soil loss for every
gallon of ethanol produced. All of these nutrients run down the
Mississippi River to the Gulf of Mexico where they exacerbate hypoxia
(i.e., low concentration of dissolved oxygen), which causes shrimp,
crabs, and fish to vacate large sections of the Gulf, 20,000 km2 in 2007 (Alexander et al., 2008).
Figure 3 also shows that most U.S. ethanol production facilities are
located in the rain-fed Midwest (NRC, 2008). But in the high plains of
Nebraska, Kansas, and Texas, cornfields are irrigated with water from
the Ogallala Aquifer, which is already overdrawn. It takes about 1,000
gallons of water to produce one gallon of ethanol from corn grown with
irrigation water. Therefore, it would take the equivalent of the water
supply of a city of more than 2 million for a single facility (a single
dark circle in Figure 3) to produce 100 million gallons of ethanol per
year.

FIGURE
3 Locations of ethanol-production facilities, both existing and under
construction in 2007. Source: Renewable Fuels Association, 2008.
In addition, ethanol production facilities require considerable
amounts of water. Each dark circle requires 3 to 4 gallons of water to
produce one gallon of ethanol. Thus a facility that produces 100
million gallons per year would use more than 300 million gallons of
water, which would come either from surface water or an aquifer. Many
aquifers in the Midwest, such as the Cambrian-Ordovician unit in Iowa
and Illinois, have already lost more than 100 feet of pressure head
through excessive withdrawals.
Most Americans do not realize how far we are from the balance necessary
for sustainability. Even if we devoted all of our agricultural land to
biofuels, we would still not produce the transportation fuel necessary
to supply our 220 million cars and trucks. Americans consume 3 to 4
gallons of petroleum per person per day. We have neither the land nor
the water to grow our way out of this problem.
In addition, biofuels policies in Europe and the United States
contribute to higher prices for corn and, thus, higher prices for food,
which is increasing hunger and poverty around the world. According to
life-cycle analyses, biofuels may not even help reduce greenhouse gases.
Perennial prairie grasses or trees would provide cellulosic feedstock
for ethanol production far superior to feedstock from corn.
Switchgrass, which was once ubiquitous on the Great Plains, could be so
again. This would restore bird habitats, improve water quality, and
sequester carbon dioxide in the soil.
However, using switchgrass (or agricultural wastes) effectively as a
feedstock for ethanol would require a breakthrough in technology, such
as the development of enzymes that can break down cellulose into starch
and sugars for fermentation or a commercially viable process for the
thermochemical conversion of cellulosic materials by gasification.
Either of these may take several years.
Global Poverty
One of the UN Millennium Development Goals is the alleviation of global
poverty, reflecting a consensus among development professionals that we
cannot solve other problems until the issue of global poverty is
addressed. More than 2 billion people live on less than $2 per day. As
long as 1.1 billion people do not have clean drinking water, and 2.4
billion do not have adequate sanitation, and 1.4 million children die
every year from clearly preventable waterborne diseases, no progress
can be made on reversing climate change, deforestation, or the loss of
species. The developed world must help developing countries solve their
pressing problems before they can help us address global issues. Today,
however, their children are still dying.
Will there be enough fresh water for 9 to 10 billion people in 2050? We
already appropriate 54 percent of fresh water resources (Postel et al.,
1996), and the average supply of water per person is decreasing as the
number of megacities and coastal development increases and rainfall
distributions continue to change. The United Nations estimates that 700
million people suffer from water scarcity today, and as many as 3
billion could face water shortages by 2025 (UN News Service, 2007).
Egypt has the smallest amount of fresh water per capita of any major
country, less than 26 cubic meters per year. Survival is possible
because Egypt imports “virtual water,” that is, liquids from fruits,
vegetables, and other products that require a great deal of water where
they are grown. In addition, the country has large national
agricultural areas in the Nile River Basin and, more recently, in the
middle of the desert (e.g., the Toshka project, an oasis where crops
are raised using groundwater and drip irrigation) (Martin, 2008).
However, as Elie Elhadj, author and water specialist in the Middle
East, has said, “You can bring in money and water, and you can make the
desert green until either the water runs out or the money” (Martin,
2008). In the long run, this scenario is simply not sustainable.
The Next Steps
Mitigation, Treatment, Action
The first thing we must do is to mitigate the causes of water shortages
as much as possible. According to most demographers, population growth
will level off sometime in the 21st century. Through education and the
empowerment of women, we may be able to limit population at the
“medium” projection in Figure 1.
The prospects for mitigating climate change depend on global
governmental resolve to decrease emissions of GHGs by 80 percent by the
end of the 21st century. At that level the atmospheric concentration of
carbon dioxide would be stabilized at approximately 450 parts per
million (Hansen et al., 2007; IPCC, 2007). Developed countries would
have to take on the heaviest responsibility for early cutbacks in
emissions (25 to 40 percent by 2025 and 80 to 95 percent by 2050), and
developing countries would be required to follow suit as their
economies begin to prosper.
Governments in developed countries must challenge their people to use
less energy and encourage a massive conversion to wind power (which is
already economical), plug-in hybrid or electric cars refueled by
electricity produced from wind energy, and water- and energy-efficient
buildings. In the United States, this will require daring changes in
policy, such as a revenue-neutral decrease in income taxes and an
increase in carbon taxes.
Energy efficiency and renewable technologies can be the engine for
economic growth and the creation of green-collar jobs. In Iowa, for
example, five new wind-power manufacturers now provide thousands of
high-paying manufacturing jobs. The end of the age of fossil fuels will
prove to be the turning point of this century. The transition away from
dependence on nonrenewable resources will be what Harvard economist
Joseph Schumpeter once called “creative destruction,” an economic
revival that replaces an old system with a better one for the future.
Water Conservation
Water conservation in the United States will be essential. Many people
think that water is scarce only in the Southwest, but a large portion
of the country is using up its water supplies through the exploitation
of aquifers and the degradation of surface waters from non-point source
pollution. Figure 4 shows the geographical areas where water is under
stress as a result of industrial and agricultural withdrawals from the
water supply. We can only hope to address our future water needs
through better water-treatment systems, the recharging and reuse of
aquifers, and water conservation.

FIGURE
4 Water stress (water withdrawals/annual precipitation) in the
contiguous United States. Areas with water stress greater than 1.0
(darkest categories) use more water than falls on that area of the
country via precipitation. Source: K.J. Hutchinson, M.S. thesis,
University of Iowa, 2008, adapted from PRISM, 2006 and USGS, 2005.
Desalination will also be important for meeting future water needs.
More than 15,000 desalination plants (mostly using reverse osmosis) are
in operation in 125 countries with a total capacity of 32 million cubic
meters of water. As the cost of desalination processes come down,
capacity will continue to rise (Zimmerman et al., 2008).
Ideally, water reuse, such as flushing toilets with gray water, will
become the norm. Aquifer storage and recovery will prevent the
evaporation of precious water supplies and help to recharge depleted
aquifers. Novel, high-quality treatment regimes will ensure that water
is treated appropriately for different uses. Engineers and scientists
will find ways to protect watersheds from pathogens, pesticides, and
endocrine-disrupting chemicals like hormones and pharmaceuticals, which
are now present in both wastewater and drinking water.
Adapting to a Changing World
Some things cannot be changed or mitigated, and for those we must adapt
as best we can. The average availability of fresh water from rivers and
ground-water (Figure 5) is likely to decrease drastically. Many
countries in Africa, the Middle East, and parts of Asia that are
particularly short of water also have the largest, fastest growing
populations and the highest levels of poverty. It is incumbent on the
developed world to help them meet their water-supply and sanitation
needs.

FIGURE
5 Map of global freshwater resources per capita from accessible rivers
and groundwater indicating that in many countries less water is
available than is recommended (<1700 m3/capita/year) according to
the World Resources Institute and the United Nations Environment
Programme. Sources: UNEP, 2002. Reprinted with permission.
Engineers are well suited to make a positive difference. We can
teach, we can create appropriate technologies, and we can serve in ways
that scientists are sometimes reluctant to undertake. For example,
Engineers for a Sustainable World, Engineers without Borders,
Inter-national Rotary, and many other groups offer people-to-people
programs that provide assistance for professional development.
Adapting to a changing world may simply mean working together within a
common framework to improve water quality. For example, World Water
Monitoring Day (WWMD), sponsored by the Water Environment Federation,
was initiated in 2002 as an international outreach program to increase
public awareness and involvement in protecting water resources. More
than 80,000 participants worldwide are monitoring streams, rivers,
lakes, and estuaries in 50 countries for dissolved oxygen,
transparency, temperature, and pH. To join, one simply registers a
monitoring site, purchases a rudimentary test kit for about $20,
monitors during the test period of September 18 through October 18, and
enters the results on the organization’s website (www.worldmonitoringday.org).
Imagine if millions of 5th graders throughout the world were enlisted
to monitor water sites. Just suppose that tomorrow at noon every
schoolchild walks to a creek, stream, lake, or drinking water source
near his or her home and records a scientific observation—the
temperature, clarity, pH, or dissolved oxygen in the water at that
site. They then file their data via the Internet, and the next day they
collectively publish a map of worldwide water quality. We can hope that
they will also think, or are taught, about the science behind the
results and that they will be motivated to improve the environment.
These volunteers would constitute a network of “water watchdogs” for
the entire planet. This is the kind of project that can transcend
geopolitics.
Modeling, Predicting, and Forecasting
Some engineers are already embracing new technologies that are capable
of making a positive difference for the environment. One such effort is
the WATERS Network (Water and Environmental Research Systems Network),
a $300 million proposal to the National Science Foundation for a
capital investment to revolutionize the modeling, predicting, and
forecasting of the quantity and quality of water (Montgomery et al.,
2007).
Figure 6 is a schematic drawing of a field facility, one node in a
national network of sites that span the physiographic characteristics
of water resources throughout the country. The facility makes use of
breakthroughs in technology, like novel sensors, wireless and broadband
technologies, high-performance computing, and real-time data
assimilation, to predict and forecast the types and amounts of water
constituents (nutrients, sediments, pathogens, and emerging chemical
contaminants). Such a system could be used to control or warn of the
likelihood of floods, harmful algal blooms, the entry of
disease-causing microorganisms into a water supply, or Gulf hypoxia.

FIGURE
6 An environmental field facility in the proposed WATERS Network. The
facility uses breakthrough technologies to
predict and forecast capabilities for water-quality constituents (e.g.,
nutrients, sediments, pathogens, and emerging chemical contaminants).
This national initiative will use real-time environmental sensing to
conduct multi-scale research and experimentation on U.S. water
resources. The WATERS Network will integrate, complement, and leverage
existing investments in water monitoring operated by various federal
and state agencies, as well as river-basin commissions and others.
The goal of the WATERS Network is to improve our understanding of
Earth’s water resources and related biogeochemical cycles, which could
lead to better management of critical water processes that interact
with human activities. Through the WATERS Network, hydrologists and
environmental engineers will develop skills in predicting water
availability and quality, and economists and social scientists will
improve forecasts of water availability and provide reliable input for
decision makers.
Modern networks like WATERS can provide a way for us to address
critical science and engineering questions to mitigate and adapt to the
changes threatening our water resources. Data fusion and assimilation
techniques that can “bootstrap” model performance, prediction, and
forecasting of water quality and quantity throughout the country could
lead to more efficient and effective water and wastewater treatment and
collection systems. WATERS represents just one initiative that might
help us learn to live with a changing water environment.
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About the Author
Jerald L. Schnoor is
Allen S. Henry Chair Professor, Department of Civil and Environmental
Engineering, University of Iowa, and an NAE member.
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