Environmental Engineering Reference
In-Depth Information
HISTORY REPEATS ITSELF
The series of dams developed in the United States over the last cen-
tury enabled this country to establish a more extensive water sup-
ply system than many other countries. It also kept the United States
about 50 years ahead when it came to maintaining adequate water
supplies. Other parts of the world with water problems similar
to those of the United States simply started earlier, says Sandia
National Laboratories' Mike Hightower.
The world water shortage started in the 1940s and 1950s, especially
in the Middle East, which didn't have river and dam systems to utilize
and store water. Those countries followed a natural progression when
it came to tapping what water resources they had. First, says Hightower,
they looked to surface water to meet their needs, then groundwater,
and, as they used that up, they turned to widespread water conserva-
tion, major water reuse projects, and coastal desalination. “We're see-
ing the same progression in the United States. We built lots of dams in
the 1930s and '40s to develop our fresh surface water supplies, so we
have more resources than other parts of the world. But in the 1970s,
we turned to greater groundwater pumping. Now we're using up those
resources and have limitations on our fresh surface water supplies.
We're going to have to make extensive changes in the next 25 years to
address those emerging water shortages,” Hightower adds.
Cities, towns, municipalities, and states across the country—
even the federal government—have their own issues and ways of
dealing with water. The themes, however, are similar: too much
demand for too little of the resource, quarrels over ownership of
or rights to the water, how the resource is being used (or not), and
pollution related to it. That leads to the world water equation:
Growing demand
Limited supply
Shortage and confl ict
over what's left
Let's look closer at some of the causes and effects.
CLIMATE CHANGE
Obviously, climate—wet or dry and degrees in between—has a huge
impact on the availability of water. Arid climates have less water, less
