Watersheds refer to how water moves
through a given area. Water may be pure H2O when it starts the process
from precipitation, but gains dissolved substances as it moves throughout
the system. For instance, as water erodes through rocks, it dissolves
the minerals that make up rocks.
Water is a universal solvent, which basically
means many compounds and elements can dissolve within the matrix of water.
The substances are dissolved usually in the “ionic” form which are easy
for organisms to take it out of the water. For instances, dissolved
oxygen is easily dissolved at the atmosphere water interface, which is
used by the fauna that lives in the water.
Every place where humans live have to consider
their water supply. Throughout history, humans that were able to
maintain water supplies were the most successful. The Romans are
noted for their ability to keep a water supply through the use of
aqueducts. Large droughts in Egypt probably lead to part of its downfall
as a great civilization.
Cities that sustain large populations, like
New York City, have to think about where their water comes from and how
to maintain a flow. City and state officials have to think about
how to maintain the water supply in times of drought and even have to think
about what happens when there is too much water.
Water issues in the United States are very
complicated and different from state to state. For instance, most
of California would be a desert if different cities didn’t buy water rights
from different areas. Los Angeles, for example, owns water
rights as far as Nevada, and San Francisco owns rights in the Sierra Nevada.
California's agricultural business is greatly
dependent upon water. Without water, the Central Valley, Sacramento Valley,
and San Fernando Valley would not be centers of agriculture. Most
of these areas would be deserts if it wasn't for water especially in the
southern portion of the state. California's fight for water is very
important, especially when the distribution of water is so uneven.
The northern part of the state naturally has water, but the southern half
does not get enough rainfall. The California Aqueduct, one of the
largest man-made structures in the world, brings northern water to the
south. The southern part of the state has also "trapped" part of
the Colorado River through the Colorado aqueduct. The capture of
water by southern California has a very intriguing history especially in
the early 1900's.
California needs its reservoirs and dams to
secure that water will always be available. Drought conditions are
common throughout history in California. To insure the availability
of water California had developed a system of reservoirs and dams.
- Discuss with students the
need for clean water for a prosperous civilization. Emphasize that
the United States provides its citizens with some of the best quality water
throughout the world.
- Conduct an internet search on your
own state. You can go to the Environmental Protection Agency website
on watersheds to help guide you (http://www.epa.gov/surf/
You might want to create a worksheet specific
to your state, like the one on California.
- Maps should be available for students
of California so they can locate the major waterways in order to complete
the worksheet. The answers are on the map below.