A poster using ArcMAP, ArcGIS and Erdas Imagine to capture high quality images and study Lake Mead and its shrinking water volume. This project sparked my interested in GIS which continues to grow to this day.

1. Tom Adamson / 51768212 / GG3069
● Lake Mead is located 25 miles from the Las Vegas strip and is the largest manmade reservoir in the United States
of America. It supplies 37 million people with water annually and can hold up to 29 million acre-feet of water.
● 97% of the freshwater inflow is sourced from the snowmelt of the Wyoming, Utah and Colorado Mountains, and
since the 1980’s, “ the winter supplies have been uneven and generally below average.” (Carlowitcz, 2018)
● This poster uses Geographical Information Systems (GIS) using satellite imagery to show and interpret extensive
waterline changes at Lake Mead. Reservoirs “play an important role in regulating climate change by their contributions
to the global carbon cycle.” (Williamson and Saros, 2008) Focus will be on the south west region; Boulder Basin.
Figure 1
(1) Remote sensing data was downloaded from the USGS
Earth Explorer website. Datasets were of Landsat 8 from
September 2018 and Landsat 4-5 from November 1983 and
2011 with less than 10% cloud coverage in daylight
(2) EREDAS Imagine 9.3 was used to stack the Landsat 4-5
images and create a 5-band composite containing bands 1-5
TIFF files from each dataset. With Landsat 8, I used ArcGIS to
create an 8-band composite of TIFF files 2-5.
(3) Then I used ArcGIS to combine and overlay information
from each dataset. Shapefiles and measurement tools
outlined key differences. Contour lines were developed from
ASTER GDEM, manipulated and labelled in Arc by rasterizing
the imagery through the Spatial Analyst Tools.
● Figure 4 shows extensive change in Lake Mead’s water levels, decreasing from 365m above sea level in
1983, to 335m in 2018. Figure 2 shows how elevation goes below 400m around Boulder Basin which is close to
the storage capacity, but figure 4 shows that hasn't been reached since the 1980’s and early 2000’s.
● Figure 6 shows the decreasing waterline. Areas submerged in 1983 area revealed in 2018. As water volume
decreases, so does surface area. Quite noticeably, the rate of shrink increases after 2010, as seen in figure 3.
● Figures 5 and 7 shows a reduction in land occupation from the 80’s to the 2000’s, were water levels began
to fall at the rate of 3m a year. In that time, the lake fell over 30m. The imbalanced water inflow-outflow ratio
has worsened the Lake condition. Despite an extension at Hoover Dam in the south, net water loss is positive.
References – Includes the Watermaster Office Daily Logs Records – Las Vegas, Nevada.
Williamson, C. and Saros, J. (2008). What Do Lakes and Reservoirs Tell Us About Climate
Change?: Chapman Conference on Lakes as Sentinels, Integrators, and Regulators of Climate
Change; Incline Village, Nevada, 8-10 September 2008. Eos, Transactions American Geophysical
Union, 89(52), pp.546-546. Also used the Hoover Dam Control Room report.
Carlowicz, M. (2018). Lake Mead Still Shrinking. [online] Earthobservatory.nasa.gov. Available
at: https://earthobservatory.nasa.gov/ [Accessed 23 Oct. 2018].
Figure 2
Figure 5 Figure 6
Figure 7
Discussion and Conclusion
Results
in Meters
Introduction
Method
Figure 3
Figure 4
● Water loss at Lake Mead can be attributed to Las Vegas which has tripled in
size since 1983. As the city grows, so does the amount of freshwater required to
fulfil its needs. Water in-flow restrictions is due to greater water usage upstream.
● Because much of the water inflow is from snowmelt, extreme droughts (D3)
in 2005 and 2011 accelerated lake shrink. As a result, storage capacity has
struggled to reach over 40%. In 2000, it spiked to 96% but has fallen since.
● Over 25°C heat has increased the evaporation of water molecules in the air.
● Lake Mead has been shrinking since 1983, and has began shrinking rapidly
due to current increasing temperatures. LANDSAT 1-8 imagery is an useful source
to display environmental change, although older images have limited resolution.
● The images allowed me to explore changes in surface area and elevation
which has strong links to water capacity. It is important to utilize a wide variety of
data such as ASTER GDEM to gain a better understanding of change.
● Arc has proved useful in visualizing and analysing change in this reservoir.