Part A: Reservoirs
on the Colorado River
Stop and think
Consider what the "squiggly lines" on the graphs
of page 2 in the "How Low Can it Go?" article really mean... Use the
graph of Lake Mead levels to describe a brief history of the reservoir. Tell
when and how the reservoir got started, how long it took to fill, and mention
events that affected its level.
Lake Mead appears to have been created in or around January
of 1937. It looks like it took about 6 months to a year to fill, and reached a
relatively sustainable height around 1939. In the 1950’s it suffered
significant drought that dipped the down below the level at which it was first
filled (somewhere around 1000 elevation ft.) It increased substantially in the
late 50’s to early 60’s. Then, after losing some water during the filling of
Lake Powell in 1967, it appears to have continually filled for several years,
actually reaching max capacity briefly in or around 1984. It maintained a
somewhat steady water flow until the more recent drought of the early 2000’s,
showing a 54%capacity at the time the article was written.
Beginning in 1964, how long did it take to capture enough
water to fill both of the large reservoirs?
Both were not actually full (at 100% capacity) until 1984 or
85, but it appears that the waters in both reservoirs peaked decently around
1974, which would have been about 7 years from the creation of Lake Powell.
The levels of Lake Powell and Lake Mead both show steep
declines in the past decade. What are the two things that control the level of
a reservoir?
Precipitation – such as from rain or runoff from melted
snow, and water consumption, such as human use for drinking, bathing, watering
lawns and filling swimming pools.
Part B: What's
Responsible for Lower Reservoir Levels?
Stop and think
Compare snowpack in a watershed to a dam on a river. How are
they alike? How are they different?
Both of these concepts allow a slow, steady source of water
throughout the year. The most advantageous part of this is that there is water
still remaining as the driest seasons come about. But, if the snow continues to
melt earlier, and the water continues to get lower, the droughts will only
continue to get worse.
What effect does the El Nino Southern Oscillation (ENSO)
have on water supplies to the Colorado River Basin?
Even when Arizona and the southern states are experiencing
wet weather, the weather patterns of ENSO do not usually deliver rainfall to
the upper basin, so the Colorado River Basin is mostly unaffected.
How does increasing population of sunbelt cities in the
Lower Colorado River Basin contribute to lowering reservoir levels?
The more people living in an area along the river, the lower
the levels become due to use, and since the river is already allocated for more
water than it actually holds, it is potentially possible to run the river
completely dry.
In your own words, describe what's responsible for lower
reservoir levels in the Colorado River Basin.
Decreased waterfall, and increased human use. We have
continually increased in population, and moved into areas along the Colorado
River. As we have done so, we have put more pressure on the river.
List at least 3 possible impacts of the decline in water
storage on the Colorado River.
The most obvious is that humans need water for survival. If
we continue to over use it now, we may not have enough to survive on. History
has shown that humans tend to build our lives around water structures, and when
the water runs out, we usually move on to a new area. Additionally, we will see
a decrease in natural habitat for animals that are native to the river. This
means that they could die, which will have a lasting impact on all animals.
Finally, we will see a destruction of the vegetation which the water feeds.
This means fewer producers. Not only will this mean fewer habitats, but less
food, and less CO2 to oxygen conversion.
Part C: Can the
River Continue to Meet Demand for Water?
Checking In
Describe the trend of water use in the states of Arizona,
California, Nevada, and the country of Mexico.
Except in the case of Mexico, water use in all areas has
significantly increased over time. California seems to be the highest use in
the U.S., but AZ has a percentage increase of 38408.374%!
How does water use in the states compare to the natural flow
of the Colorado River (see graph in Part B) over the same time period?
The river has had about a 25% cumulative decrease, while the
use has gotten significantly higher! The upper basin had about a 213% use
increase, and the lower basin had about a 334% increase, for a total average
increase of 273.5%
Stop and think
Calculate the percent
increase in AZ water consumption between the years 1906 and 2008.
Since my data only goes to 2005, I used the graph to
estimate an average of 2800000 for 2008. At which point the percentage increase
would be 38277.193%
Based on these numbers, it is ever more clear just how
likely it is that we could empty out the Colorado by 2022. With AZ already at
maximum capacity, and the population constantly on the rise, it’s only a matter
of time before we deplete the resource if we do not find another way.
Checking In
How might the change in water levels affect you as a
recreational boater? Give a specific example, naming features that are labeled
in the pair of images.
Water levels decreasing will mean new water hazards in the
water in many locations. In addition, many areas which may have been accessible
by boat or Jet Ski, and may even be listed as accessible on some maps, will now
be more or less impassible. For example, I note that water ways near Las Vegas
Island are much narrower, and mostly land at this point. My family and I used
to spend some time boating around Black Island when I was a kid, and now this
isn’t even an island.
Stop and think
Given that long term changes in climate are reducing inflows
into the reservoir, and that outflows through Hoover Dam are growing to meet
demand by an increasing population, what is the projected result in the
reservoir? What would you need to know in order to predict the date of the
result?
Based on the current data, water is leaving faster than it
is coming in, and the reservoir will be emptied. In order to know when, I would
need to know the exact rates of inflow to output.
Based on data you examined in this lesson as well as other
sources, do you think that reservoirs in arid lands prevent or merely postpone
water shortages?
It seems pretty obvious that they are only being postponed.
Part D: Is Drought Here to Stay?
Stop and think
List the title of the photograph you chose and write a short
paragraph to summarize the issue it illustrates.
I can’t find the name of the photo, and I have to register
to the site to read the whole article, which I would rather not do. The caption
reads: Owens Lake became a wasteland when in 1913 Los Angeles began diverting
the river that fed it to quench the growing metropolis's thirst. Today
salt-loving bacteria thrive in brine pools on the dry lake bed, lending a
blood-red tint in this aerial view. A mining road cuts through the middle of
the image.” The issue the photo illustrates is that increased population can
literally destroy a river with its demand. Not only did LA run out of water
from this location, but they have forever altered the landscape and the lives
of animals that relied upon it.
Stop and think
Summarize the positive outlook with which the researchers
end the article.
Researchers indicate that if we take measures now, it should
be possible to devise solutions to our water problem. The technology to measure
and monitor is available, and at a reasonable cost. The only question is when,
and perhaps whether or not, people will make the choice to start doing
something about the water crises.
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