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Everything is linked below. It is due in 4 hours.Assignment 2 – This assignment is due by Sunday, October 11th, at 11:59 PM.
Upload it to the d2l assignments tab in the Assignment 2 folder. (20 pts total)

In this assignment you will be using the reading on the Basin and Range Aquifers to
answer the questions below. The reading can be found on d2l under content/Week 7, at
the bottom, right under this assignment. Question 1 is a general question that you should
be able to answer from what you have learned in lecture videos. The rest will require you
to do some digging within the text of the paper. There are figures referred to within the
text, and these can be found at the end of the paper.

1. What is an aquifer? (1 pt)

2. For what parts of the U.S. are basin and range aquifers the principal source of
groundwater? (1 pt)

3. In terms of ground water and aquifers, what is recharge? (1 pt)

4. What is the primary source of recharge to the basin and range aquifers (i.e. where does
the water come from)? (1 pt)

5. How does the generally arid climate of the basin and range region affect the water
cycle, primarily recharge of the aquifers? (1 pt)

6. How much of the precipitation that falls actually recharges these aquifers? (1 pt)

7. How does human intervention in the hydrologic cycle provide additional recharge to
the aquifers, mainly in developed areas? (1 pt)

8. In terms of groundwater and aquifers, what is discharge? (1 pt)

9. What are three ways water is discharged from these aquifers, and what is the largest
natural component of groundwater discharge from these aquifers? (2 pts)

10. What do you think is the largest component of discharge from the basin and range
aquifers overall (natural or unnatural)? (hint: you can find the answer farther along in the
reading, but make an educated prediction before you look it up) (1 pt)

11. About how much groundwater is in storage in the basins in Arizona and Utah? Is all
of this water fit for human consumption? Why or why not? (2 pts)

12. Has Arizona or Utah had larger water level declines in general? Why? (2 pts)

13. What is most of the groundwater that is withdrawn from these aquifers used for? (1

14. Where are some of the largest rates of groundwater withdrawal from these aquifers
occurring? Why? (2 pts)

15. What is one negative effect of high rates of groundwater withdrawal in Arizona?
Explain what it is and why it is a negative effect. (2 pts)BASIN AND RANGE AQUIFERS


The Basin and Range aquifers extend through about 200,000 square miles of the southwestern United
States and underlie most of Nevada and parts of eastern California, southern Oregon and Idaho, western
Utah, southern Arizona, and southwestern New Mexico. The aquifers as described in this report include the
aquifers of western Utah, southern Arizona, and southwestern New Mexico (fig. 31). The aquifers comprise
the eastern part of the Great Basin aquifer system in Utah and the western part of the Southwest alluvial
basins aquifer system in Arizona as defined by U.S. Geological Survey Regional Aquifer-System Analysis

The Basin and Range aquifers are the principal sources of ground water in western Utah and southern
Arizona. The aquifers are present in about 120 alluvium-filled basins interspersed between ranges of
mountains (fig 32). About 150,000,000 acre-feet of recoverable ground water is in storage in the upper 100
feet of the saturated sediments of these basins. The ground water in some basins is extensively utilized, and
large water-level declines have occurred; in other basins, population is sparse, ground water is little
utilized, and water levels are stable.

The 95,000-square-mile area of the aquifers in Segment 2 ranges in altitude from about 150 feet near Yuma
in southwestern Arizona to more than 10,000 feet at the crests of a few desert mountain ranges. Most of the
mountain ranges protrude 3,000 to 6,000 feet above the level of the surrounding basins and extend in a
northerly or northwesterly direction for 10 to 50 miles. The land surface of the basins generally slopes
gently from the adjacent mountain fronts toward the flat-lying central parts of the basins, where dry lake
beds (playas) or shallow sandy stream channels are common. Some basins are topographically closed, and
all surface water drains to a central lake or playa; other basins are topographically open, and surface water
may flow between basins. The high temperatures and arid climate of the desert region result in minimal
stream flow, and the stream channels and playas generally are dry.


Structure and rock type are the principal geologic factors that affect the occurrence and movement of
ground water in the Basin and Range aquifers. The principal aquifers are in thick deposits of basin fill
(sediments) in valleys bounded by mountain ranges formed mostly of relatively impermeable bedrock.

The structural deformation that produced the system of basins and ranges generally began in Tertiary time
with block faulting along steeply dipping normal faults. Crustal extension produced horst and graben
blocks in some places, and tilted blocks in others. The downthrown parts of the blocks became basins; the
upthrown parts became mountain ranges (fig 33). Vertical displacement across the fault zones exceeded
10,000 feet in some areas. Many of the resulting basins are asymmetrical becau

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