Lab 4 Drought in SW US.docx (2)
pdf
keyboard_arrow_up
School
Binghamton University *
*We aren’t endorsed by this school
Course
116
Subject
Geology
Date
Dec 6, 2023
Type
Pages
6
Uploaded by EarlChimpanzee972
Geol 116, Fall 2023
Name ____
_Kyra Hooshi
_________
Lab 4: Drying of the American West
Based on an exercise from the EarthLabs project, SERC, Carleton College
Part A: Reservoirs on the Colorado River
The Colorado River drains a huge area of the arid southwestern United States. While the source of much of its
water is from the high country on the western side of the Rocky Mountains, the main river flows through
desolate canyons and dry desert areas. By building dams across the river, we have been able to hold back some
of the water that would otherwise flow downstream. The result is a series of reservoirs of "saved" water that
can be tapped as it is needed. The river that carved the Grand Canyon is now responsible for providing water
for people and agriculture across the southwest.
1.
Examine the map on the next page to get familiar with the location and setting of the Colorado River
Watershed. Focus in on the locations of the large reservoirs formed by Glen Canyon Dam (Lake Powell) and
Hoover Dam (Lake Mead).
2.
The graph below shows the
water storage
(volume of water) in the two reservoirs over the last few
decades expressed in millions of acre-feet (one acre-foot is the volume of water necessary to cover an acre
to a depth of one foot). Upper line is combined storage; lower line is the storage in Lake Mead.
3.
The next two graphs show the changes in lake levels (water surface elevation) in Lake Powell (top) and Lake
Mead (bottom) over the last few years.
4.
Summarize the patterns of change in water level and total storage that you observe from the graphs. Are
highs and lows in the reservoirs happening at the same times? Explain.
Despite both graphs having a similar shape, Lake Mead generally has a higher elevation. Starting in January,
the water level rises and drops over the course of the year, reaching its lowest point around July. Water
level increases and decreases over the year starting in January and reaches its lowest level in around July.
Comparing Lake Powell and Lake Mead, Lake Mead’s water level remains stagnant in July, while Lake
Powell’s water level increases, so the highs and lows in the reservoirs are in fact, happening at the same
time. Overall, both have decreased in elevation over the years, with a sudden increase in July this year.
5.
The following graphs show water use in acre-feet per year of the Colorado River through time and the
amount of annual flow in the Colorado River. Note that water for Mexico is the amount left over in the
Colorado River after uses in the U.S.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Describe the trend of water use in the states of Arizona, California, Nevada, and Mexico.
●
Arizona: remains at a stagnant low of around 2 million
●
California: increases gradually eventually approaching around 2 million
●
Nevada: Nevada’s water consumption is practically nonexistent
●
Mexico: the trend varies with extreme highs and lows, but ultimately descends to roughly 3 million
How does water use in the states compare to the natural flow of the Colorado River (second and third graphs
above) over the same time period?
The state's water usage and the Colorado River's natural flow are almost 1:1 when it comes to available water.
As water consumption increases, the Colorado River's natural flow fluctuates as a result of the increasing
demand.
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 (Lake Mead)? What would you need to know in order to predict the date of the result?
In order to determine how actively the population uses the lake (Lake Mead) as a water source, we need to
know how much water has been consumed by the area directly adjacent to the lake. In addition, the type of
wildlife and their natural habitat or another source of water, the body of water can be used to predict whether
consumption will eventually outpace influx.
Based on data you examined in this lab, do you think that reservoirs in arid lands prevent or merely postpone
water shortages?
As a result of reservoirs in arid lands, water shortages in those areas are only postponed. We are teaching
people how to allocate their water resources if we give them access to water and don't inform them of
possible future changes, even though a long-term solution can help make water use and availability more
consistent in the long run.
Finally, review the drought situation in the western U.S. The graph below shows the Palmer Drought Index for
the southwestern U.S. for the last 120 years.
The diagram shows a trend line. What is the trend? Do the data support the interpretation of that trend?
The trend shows a strong, steady decline in both precipitation and dryness as the years progress.
The data clearly depicts the interpretation of this trend for both available temperature and precipitation
The graph shows values moving beyond -4.0 demonstrating more severe drought conditions as time goes by,
this shows that the trend moves from more wet conditions to more dry and arid conditions. There will be a
transition from more wet years to more dry periods.
What does everything you’ve examined in this lab imply for near-term and future water availability for the
southwest US?
According to this lab, future water availability will be more scarce, and droughts will occur more frequently
than they used to. Hence, a viable solution to prevent this would be to source water across multiple bodies of
water in the US rather than relying on one single large source, which would eventually dry up and affect the
others too due to its role as a drop-off point for the rest (in this case, the Colorado River bodies).
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help