performance for the two dominant crops in western Turkey: cotton and
grapes. Although both crops are normally irrigated, their model showed
water productivity of grapes to be maximal without irrigation. Thus, to
minimize risk of water shortages, cropping of grapes should be expanded.
With high water availability, a mixture of grapes and cotton is preferable
for the economic benefits provided.
An example of the effect that development has on water use can be seen
by comparing water use in the United States with world water use. In 1900,
world demand was approximately 300 m
3 per person per year; in the United
States, that value was 700. In 1980, world consumption had grown to 700,
while the U.S. demand had reached 2700. In terms of these units, which
factor population growth out of the equation, water demand in the United
States had grown by a factor of 4 while world demand had increased by a
factor of only 2 (Gleick 1998). The important point here is that transforming from a developing to a developed society has greatly increased the
requirement for water. Projections of water consumption in developing
countries suggest that demand for household and industrial use could
double in the next 25 years (Swaminathan 2001).
Many authors continue to suggest that water scarcity is the resource side
of the problem that must be addressed. Former Senator Paul Simon’s (1998)
book on water, Tapped Out—The Coming World Crisis in Water and What
We Can Do about It, takes this general approach (i.e., fix the water
problems and avoid the crisis). While his concern with water and his
solutions are valid, the underlying principle of carrying capacity remains
inviolable. In the water context, climate provides a watershed with a fixed
amount of water. A minimum amount of water is required per person each
day for survival. The equation then becomes straightforward:
Human carrying capacity = Gallons of water available per year/
(Gallons per person per year demand)
Conservation and other management tools can, to some degree, change the
values in both the numerator and denominator but cannot change the
reality that a given environmental setting can support only a certain number
of people.
The water problem is one of trying to reconcile supply with demand in a
spatial context with the population. Supplies are fixed, while demand continues to grow rapidly and not always in the best locations. There has been
progress in improving management practices, but those new practices have
reduced the rate of growth in demand per person, not total consumption.
In this context, the United States can be considered a recent good news
story. By 1995, water demand in the United States had dropped from 2,700
to 2,200 m
3 per person per year, resulting in a flattening of total demand
during the past 20 years. This reduction in the rate of growth of water
demand was achievable only in concert with a small population growth rate
during the same period.
15. Using Models for Environmental Security
299
grapes. Although both crops are normally irrigated, their model showed
water productivity of grapes to be maximal without irrigation. Thus, to
minimize risk of water shortages, cropping of grapes should be expanded.
With high water availability, a mixture of grapes and cotton is preferable
for the economic benefits provided.
An example of the effect that development has on water use can be seen
by comparing water use in the United States with world water use. In 1900,
world demand was approximately 300 m
3 per person per year; in the United
States, that value was 700. In 1980, world consumption had grown to 700,
while the U.S. demand had reached 2700. In terms of these units, which
factor population growth out of the equation, water demand in the United
States had grown by a factor of 4 while world demand had increased by a
factor of only 2 (Gleick 1998). The important point here is that transforming from a developing to a developed society has greatly increased the
requirement for water. Projections of water consumption in developing
countries suggest that demand for household and industrial use could
double in the next 25 years (Swaminathan 2001).
Many authors continue to suggest that water scarcity is the resource side
of the problem that must be addressed. Former Senator Paul Simon’s (1998)
book on water, Tapped Out—The Coming World Crisis in Water and What
We Can Do about It, takes this general approach (i.e., fix the water
problems and avoid the crisis). While his concern with water and his
solutions are valid, the underlying principle of carrying capacity remains
inviolable. In the water context, climate provides a watershed with a fixed
amount of water. A minimum amount of water is required per person each
day for survival. The equation then becomes straightforward:
Human carrying capacity = Gallons of water available per year/
(Gallons per person per year demand)
Conservation and other management tools can, to some degree, change the
values in both the numerator and denominator but cannot change the
reality that a given environmental setting can support only a certain number
of people.
The water problem is one of trying to reconcile supply with demand in a
spatial context with the population. Supplies are fixed, while demand continues to grow rapidly and not always in the best locations. There has been
progress in improving management practices, but those new practices have
reduced the rate of growth in demand per person, not total consumption.
In this context, the United States can be considered a recent good news
story. By 1995, water demand in the United States had dropped from 2,700
to 2,200 m
3 per person per year, resulting in a flattening of total demand
during the past 20 years. This reduction in the rate of growth of water
demand was achievable only in concert with a small population growth rate
during the same period.
15. Using Models for Environmental Security
299