GLY4155C - Module 4 Submission Template
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University of Florida *
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Course
4155C
Subject
Geography
Date
Feb 20, 2024
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docx
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3
Uploaded by edenis5
Module 4 Assignment Submission Template
1)
(10 pts) What factors would prevent returning the Everglades to its original configuration?
By the mid-twentieth century, factors preventing the Everglades from returning to its original configuration were a vast network of canals and levees built to drain water for flood control, water supply, agriculture, and urban development, had profoundly altered the wetlands and reduced the Everglades to half its original size.
Open the “Theis calculator” spreadsheet (located under Resources on the assignment page in Canvas), and increase and decrease the transmissivity by an order of magnitude (e.g., make it 10 times great, and
then make it 10 times smaller than the original value of T). 2)
a. What is the maximum change in hydraulic head (at 0.5 m distance) and what is the change in hydraulic head at 10,000 m distance for each of the 3 values? (3 pts, 0.5 for each value)
Original Value
10X greater
10X smaller (1/10
th
)
0.5m distance
156.04
17.44
0.05
10,000 m distance
3.06
1.73
0.01
b. Use your results to summarize how transmissivity affects the change in hydraulic head. (5 pts)
3)
A transmissivity of 20,000 ft
2
/day is reasonable for the upper Floridan aquifer in South Florida. Convert this to m
2
/day so that it can be entered in the spreadsheet. Show your work. (5 pts)
18,580.61 m
2 /day
4)
Convert 5 million gallons/day to m
3
/day so that the proposed pumping rate can be entered in the spreadsheet. Show your work. (5 pts) 0.1893 m
3
/day
5)
A. If 200 wells are planned for an area that is 2000 km
2
, how many km
2
will each well cover? Show your work.
(2 pts). Note: For this calculation, you’ll assume that the wells are evenly spaced. In reality the wells will be more concentrated around the edges of Lake Okeechobee and not located within the lake.
200 x 10 km
2
=2000km
2 therefore, each well will cover 10 km
2
B. What would the spacing between wells be? (in meters) Show your
work. (5 pts) Length of side well coverage (10km
2
) = 3.16km
So, the distance between wells in meters will be 3.16 km*1000 =
3160 m
6)
Each well will have 4 neighbors that are to the N, S, West and East and
4 neighbors that are NW, SW, NE, and SE. Calculate the distance to
the “diagonal neighbors”. Show your work. (5 pts)
C = diagonal distance between wells
3.16
2
+ 3.16
2
= C
2
C
2
= 19.97 km C = 4.47 km * 1000 = 4470 m
7)
You can calculate the total pressure increase by adding the drawdown at 0.5 m to the drawdown for each of the 8 neighboring wells. What is the total pressure increase? (Check yourself: Your total should exceed the safe pressure of 66 psi). (5 pts)
8)
What did the study conclude about whether or not 333 ASR wells were realistic? (5 pts)
9)
What other concerns did the study identify as important? (5 pts)
10)
The Biscayne aquifer is a shallow unconfined limestone in South Florida that provides water to Miami and other cities. It is part of the surficial aquifer system and its transmissivity exceeds 2,000,000 ft
2
/day, which is much higher than the upper Floridan aquifer in South Florida. The Biscayne aquifer has good water quality, so mixing with aquifer water would not be a concern. What important practical issue would prevent using the Biscayne aquifer to store excess water? (10 pts)
The Biscayne aquifer is highly permeable and is at or near land surface practically everywhere. It is readily susceptible to groundwater contamination. 11)
The Boulder Zone, located in the lower Floridan aquifer has extremely high transmissivity, averaging 25,000,000 ft
2
/day. Convert this to m
2
/day and use the “Theis calculator” spreadsheet to calculate the total pressure increase. (5 pts) 2322576 m
2
12)
As you calculated above, pressure increase is not a problem if the water were to be injected into
the Boulder Zone. This is one of the reasons that it is often used to dispose wastewater. However, simulations found that if freshwater were injected into the Boulder Zone for ASR, it would be “lost” and not recoverable. Why is loss of the freshwater likely to occur at extremely high transmissivities? (5 pts) Loss of freshwater would occur at extremely high transmissivities because high transmissivities are characterized by shallow and wide cones.
13)
Based on the reading in Hine’s Geologic History of Florida, what has caused fracturing in Florida?
(5 pts) The collision of the Greater Antilles Cretaceous volcanic arc with the Bahamas, Florida, and Yucatan passive margin. The compressional forces created the Florida Platform could have started fracturing and faulting in the older carbonated rocks. 14)
A seismic reflection study
examined the subsurface south and east of Lake Okeechobee. What did they find and what are the implications/concerns for water storage? (If you’re interested, implications are discussed further in this fact sheet
). (10 pts) Sustainable development and management of water supply is unclear because of the potential risks posed by structural geological anomalies like faults, fractures, karst collapse structures and geological gaps in the stratigraphy of the system.
15)
On page 125, Hine’s Geologic History of Florida suggests the possibility that dissolution at depth could be caused by mixing of freshwater and saltwater. An alternate possibility is that the deep caves (such as in the Boulder Zone) formed long ago, when the formations were near the surface and could have been dissolved by rainfall. Suggest how you might test which hypothesis is correct and whether or not dissolution at depth is still active today. ( 10 pts)
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