Earths Water Sources

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Earths Water Sources
Water-The Source of Life
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Table of Contents

• Oceans
• Lakes
• Ground Water
• Distribution of Water

• Glaciers
• Rivers
• Water Cycle
• Credits

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Rivers
What is a river? Where does the water come
from? Why are rivers important? River
Pollution River Pollution Control
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What is a river?

• A river is nothing more than surface water
  finding its way over land from a higher altitude
  to a lower altitude, all due to gravity. When
  rain falls on the land, it either seeps into the
  ground or becomes runoff, which flows downhill
  into rivers and lakes, on its way towards the
  seas. In most landscapes the land is not
  perfectly flat -- it slopes downhill in some
  direction. Flowing water finds its way downhill
  initially as small creeks. As small creeks flow
  downhill they merge to form larger streams and
  rivers. Rivers eventually end up flowing into the
  oceans.

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Where does the water come from?

• The water in a river doesn't all come from
  surface runoff. Rain falling on the land also
  seeps into the earth to form ground water. At a
  certain depth below the land surface, called the
  water table, the ground becomes saturated with
  water. If a river bank happens to cut into this
  saturated layer, as most rivers do, then water
  will seep out of the ground into the river.
  Ground-water seepage can sometimes be seen when a
  road is built through water-bearing layers, and
  even on a driveway! Saturated, water-bearing
  materials often exist in horizontal layers
  beneath the land surface. Since rivers, in time,
  may cut vertically into the ground as they flow,
  the water-bearing layers of rock can become
  exposed on the river banks. Thus, some of the
  water in rivers is attributed to flow coming out
  of the banks. This is why even during droughts
  there is usually some water in streams.

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Importance of Rivers

• Rivers are invaluable to not only people, but to
  life everywhere. Not only are rivers a great
  place for people to play, but people use river
  water for drinking-water supplies and irrigation
  water, to produce electricity, to flush away
  wastes (hopefully, but not always, treated
  wastes), to transport merchandise, and to obtain
  food. Rivers are major aquatic landscapes for all
  manners of plants and animals. Rivers even help
  keep the aquifers underground full of water by
  discharging water downward through their
  streambeds. And, we've already mentioned that the
  oceans stay full of water because rivers and
  runoff continually refreshes them.

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Pollution
As the water runs off of the land and back to the
oceans, it carries with it many substances that
it picks up along its way. It could run through a
pool of gasoline spilled at the pump, loose dirt
from the construction site, or fertilizers from
the golf course. Also many serious diseases, such
as cholera, are caused by drinking water that
contains parasitic microorganisms. Water
containing large amounts of industrial waste or
agricultural chemicals (e.g., pesticides) can
also be toxic. All of these cause pollution in
the marine environment pollution that not even
the most modern equipment can clean up.
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Pollution Control
In response to this need for reliable supplies of
clean and usable freshwater, governments at all
levels have formed organizations and passed
legislation to monitor, treat, and protect our
water supplies. The Clean Water Act established
the policy of contracting water-treatment
facilities and implemented enforcement procedures
to ensure that our water supplies would be kept
clean for human use. Later, the Safe Drinking
Water Act of 1974 established minimum federal
public-health standards for the water supply. The
policies and standards provided by these acts,
together with a large body of legislation
developed at the state and local levels, have
helped to ensure that residents of almost every
part of the United States have access to a safe,
usable supply of water for drinking and other
uses. We can also help protect the water supply
by not littering and picking up trash when we see
it on the ground. We can also tell people, who we
see doing something that will harm the water, to
stop.
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Water Distribution
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The Water Cycle
Rivers and Coast Water Cycle
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Credits
Human Use of Freshwater
Rivers and Streams
Sources of Pollution
Streamflow
Water Cycle
Image - Forest River
Image - River
Image - River Fishing
Image - Water Runoff
Image - Water Table
Water Cycle Animation