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Earths Water Sources

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Title: Earths Water Sources


1
Earths Water Sources
Water-The Source of Life
2
Table of Contents
  • Oceans
  • Lakes
  • Ground Water
  • Distribution of Water
  • Glaciers
  • Rivers
  • Water Cycle
  • Credits

3
Rivers
What is a river? Where does the water come
from? Why are rivers important? River
Pollution River Pollution Control
4
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.

5
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.

6
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.

7
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.
8
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.
9
Water Distribution
10
The Water Cycle
Rivers and Coast Water Cycle
11
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
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