FOR RELEASE: Jan. 20, 1997
Contact: Roger Segelken
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End Irrigation Subsidies And Reward Conservation
ITHACA, N.Y. -- Unless the world's food-growing nations improve their
resource-management practices, life in the 21st century will be as tough as
it is now in the 80 countries that already suffer serious water shortages,
a new Cornell University study warns.
As a start, governments should end irrigation subsidies that encourage
inefficient use of water and instead reward conservation, according the
report, "Water Resources: Agriculture, the Environment and Society,"
published in the February 1997 issue of the journal, BioScience.
"Undercharging for irrigation water in the U.S. and other nations hides the
true cost of food and encourages the planting of low-value crops," said
David Pimentel, professor of ecology in Cornell's College of Agriculture
and Life Sciences, leader of the 10-researcher team that performed the
water-resource analysis. "If farmers paid the full cost of water, they
would manage irrigation water more efficiently. We should reward water
conservation, not water use."
The study examined factors responsible for a worsening shortage of fresh
water, including usage that is increasing out of proportion to population
increases. While the world population increased from 3.8 billion to 5.4
billion during the recent two decades, water use worldwide increased
three-fold, the analysts found.
Whether or not humans are to blame for global warming, we can expect
changes that are difficult to predict, the report observed. For example, a
warmer California, which already is experiencing water shortages, might see
a 20- to 40-percent decrease in mountain snowpack and water flow through
its river basins, the Cornell researchers found. And warmer temperatures
would melt the California snowpack earlier in the year, creating severe
water shortages in the summer.
Farther north on a warmer globe Canada might benefit from longer growing
seasons, but also face water shortages, according to one prediction cited
by the Cornell team. Overall, global warming could increase the world's
irrigation needs by 26 percent while worsening deforestation,
desertification and soil erosion -- all of which affect water resources.
Our taste for meat is costly in terms of water, Pimentel noted. Producing
a pound of animal protein requires, on average, about 100 times more water
than producing a pound of vegetable protein. But some animals are
thriftier, he noted: Whereas growing the grain to feed cattle requires
12,000 gallons of water for every pound of beef, chicken can be produced
for "only" 420 gallons of water per pound of meat.
Not only is irrigation becoming more costly, in terms of energy
expenditures, as underground aquifers run dry and water has to be pumped
from greater depths, but energy production is taking more water, according
to the study. Oil shale, coal gasification or coal liquefaction -- the
last of the fossil fuel sources as the world's supplies of oil and natural
gas are depleted -- require 20 to 50 times more water to produce an
equivalent amount of energy, compared to oil and gas.
The study predicts heightened international tensions when shared rivers
dwindle as they flow through countries that siphon off their share.
Pointing to the Nile, which passes through the Sudan, Ethiopia, Egypt,
Burundi, Kenya, Rwanda, Tanzania, Zaire, Eritrea and Uganda on the way to
the Mediterranean, the researchers said: "This river is so dammed and
overused that for parts of the year little or no fresh water reaches the
sea. All these nations are becoming increasingly dependent on the Nile as
their populations increase and their food situation worsens."
To make matters worse, much of the water for irrigation never reaches the
crops, the study reported, because of losses through pumping and
transporting. Worldwide, irrigation efficiency is less than 40 percent,
and U.S. growers don't do much better, losing more than 50 percent of
irrigation water. Among the technologies and practices suggested to
improve efficiency are surge flow irrigation (to replace the traditional
method of slow, continuous flooding) as well as night irrigation,
low-pressure sprinklers, low-energy precision application and drip
irrigation, all help reduce losses by evaporation.
An old agricultural practice -- planting trees as "shelter belts" along
with food crops -- can reduce evaporation from soil and transpiration from
crops while reducing wind erosion of soils by as much as 50 percent, the
researchers suggested. In particular, they recommend intercropping crops
with "hydraulic lifter" trees, such as eucalyptus, which draw moisture from
deep in the soil at night and make it available to surrounding plants.
Intercropping also reduces soil erosion, the study observed, noting that
the loss of topsoil cuts rainwater infiltration by 93 percent and
dramatically increases water runoff and loss. When water runs off farmed
land, it carries with it not only sediments but nutrients and pesticides,
making soil erosion the leading cause of non-point source pollution in the
United States.
Some changes in practice will be involuntary, the water-resource study
predicted: "In the future, in arid regions where ground water resources
are the primary source of water, irrigation probably will have to be
curtailed and types of crops and livestock maintained altered to meet the
changing water situation."
But policy changes can help, the researchers said: "To encourage
conservation, subsidies for irrigation water should be phased out to
increase overall efficiency. Irrigation technologies that make efficient
use of water for crop production must be encouraged. In general, more
effective use of water in agricultural production could be achieved by
providing farmers incentives to conserve water and soil resources."
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10 not-so-dry facts about water resources
>From "Water Resources: Agriculture, the Environment and Society"
By D. Pimentel, J. Houser, E. Preiss, O. White, H. Fang, L. Mesnick, T.
Barsky, S. Tariche, J. Schreck and S. Alpert
-- Thirsty plants. Agriculture consumes 87 percent of the fresh water
withdrawn in the world.
-- Lucky break. Earth's atmosphere is the source of all the rain that
falls, returning to the surface water that evaporates from the oceans and
land areas. But the distribution is not equal, and that's lucky for
land-dwellers: Although only 14 percent of evaporation occurs from land,
about 24 percent of the world's precipitation falls onto land.
-- Water guzzlers. Humans need only 1 to 2 quarts of water per day to
stay alive, but we use much more. Americans use about 100 gallons of
water per person per day for drinking, cooking, washing, disposing of
wastes and other personal purposes -- much higher than the world average
of about 22 gallons per person per day. Counting irrigation and all other
uses, Americans account for 1,350 gallons per person per day. The
worldwide average is 475 gallons for all uses, and in China the average is
even less -- 290 gallons.
-- More thirsty plants. A squash plant transpires 10 times its weight in
water per day. Many deciduous trees transpire 2 to 6 times their weight.
-- Water bill. Depending on the water quality and purification treatments
used, potable water costs from $1.1- to $1.25 per 1,000 gallons. Add 50
cents per 1,000 gallons if charcoal filtration is needed and another 80
cents if salts have to be removed. To desalinate ocean water costs as much
as $7.60 per 1,000 gallons.
-- Out of sight. In the United States, ground water provides about 46
percent of the water used by all households, and agriculture takes even
more: About 66 percent of irrigation water in Texas and 38 percent in
California is pumped from ground water.
-- Deficit pumping. The Ogallala aquifer that underlies parts of Nebraska,
Kansas, Colorado, Oklahoma, New Mexico and Texas is almost one-half
depleted. Recharge rates for the Ogallala aquifer are only a small
fraction of the withdrawals.
-- No rain, no gain. Some countries are worse off, having little ground
water and receiving practically no rain. Egypt, for example, gets 97
percent of its water from the Nile, which flows from its upstream
neighbors. Of the 14 Middle Eastern countries, nine face serious water
shortages.
-- Dangerous drink. Agricultural and industrial chemicals and the lack of
community sanitary facilities are the primary causes of water pollution.
In developing countries, about 90 percent of all illnesses result from
waterborne parasites and pathogens.
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