Geology 110: Earth and Space Science
Chapter 11 (Streams and Floods)
Homework
SELF-REFLECTION AND COMPREHENSION SURVEYS
Checkpoint 11.1, p. 294
#1: Sort the following twelve terms into six pairs of terms that most closely relate to one
another.
groundwater, stream, rainfall, gas, plants, ice, precipitation, melt water,
transpiration, infiltration, water vapor, run off
Checkpoint 11.2, p. 295 (not required, not extra credit)
#2: Imagine that it rained continuously all over the world for a month. If we were to
measure the depth of the oceans over a 5-day period near the end of the month, what
would we observe? Explain your choice.
a) Ocean depths rise steadily
b) Ocean depths fall steadily
c) Ocean depths stay the same
Checkpoint 11.3, p. 295
#3: Use the hydrologic cycle to suggest a hypothesis about why rivers in South America
carry approximately twice as much freshwater as do rivers in North America.
Checkpoint 11.4, p. 295 (not required, not extra credit)
#4: Draw a concept map that identifies the links among the components of the Earth
system and the hydrologic cycle.
Checkpoint 11.5, p. 297
#5: Why is the volume of water in the Mississippi River about 10 times greater than the
volume of water in the Nile River?
a) The Mississippi River drainage basin is ten times bigger than the Nile basin.
b) The Mississippi River drainage basin receives more rain.
c) The Mississippi River is a longer stream.
d) There is less vegetation to absorb rainfall in the Mississippi River drainage basin.
Checkpoint 11.6, p. 297 (not required, not extra credit)
#6: Rivers in Iowa flow to either the Mississippi River, which makes up the eastern state
border, or the Missouri River on the western state border. Draw the drainage divide for
the Missouri and Mississippi basins in Iowa on the map provided here.
Checkpoint 11.7, p. 297 (required all classes…for notebook, online classes)
#7: Examine the map of rivers in southern Georgia below. Draw on the approximate
boundaries of the drainage basins for the named streams. Note that the Savannah and St.
Mary Rivers mark parts of the eastern boundary of the state. Do not include the Savannah
or St. Mary Rivers’ drainage basins.
Checkpoint 11.8, p. 298
#8: What type of river systems can you observe in this map of part of the Appalachian
Mountains and adjacent areas? Explain any differences in patterns that you observe in
different parts of the map.
Checkpoint 11.9, p. 300
#9: Explain why stream velocity would change along the same section of a stream at
different times of the year.
Checkpoint 11.10, p. 301 (extra credit, all classes)
#10: Examine the three streams represented in the following drawing. Which stream has
the highest hydraulic radius?
a) Stream A
b) Stream B
c) Stream C
Two rivers (this question not related to diagram above) have the same channel roughness,
stream gradient, and depth. Stream A is twice as wide as stream B. Which stream has the
greater velocity?
a) Stream A
b) Stream B
c) Neither, the velocity is the same
Checkpoint 11.11, p. 301
#11: Some scientists predict that global warming will result in a corresponding increase
in evaporation. How would this impact the discharge of the Amazon River?
a) Discharge would increase
b) Discharge would decrease
c) Discharge will stay the same
Checkpoint 11.12, p. 301(not required, not extra credit)
#12: Create a concept map that illustrates the connections among the factors that
influence stream flow. Include the following eight terms and up to four more of your own
choosing.
Discharge
Velocity
Wetted Perimeter
Depth
Gradient
Channel Roughness Cross section area
Width
Checkpoint 11.13, p. 304
#13: What statement is most likely true about a pebble found in a stream?
a) It formed from erosion of sedimentary rock in the adjacent streambed or bank.
b) It formed when sand and clay clumped together in the stream.
c) It is younger in age than the stream channel.
d) It may be composed of any type of rock.
Checkpoint 11.14, p. 304
#14: Consider the consequences of constructing a dam on a river with a large stream load,
such as the Yellow River. Assume the dam and its reservoir are located about two-thirds
of the way down the river. How would stream flow conditions be altered above and
below the dam and its reservoir? What would be the implications for erosion, transport,
and deposition?
Checkpoint 11.15, p. 308 (extra credit, all classes…for notebook online classes)
#15: Image Analysis: Mississippi River Radar Image
Examine the accompanying image of part of the lower course of the Mississippi River.
This picture was taken by the Spaceborne Imaging Radar aboard the Space Shuttle. The
long axis of the image is approximately 40 kilometers (67 miles) in length. North is to the
top right. This section of the river represents part of the state borders of Arkansas,
Louisiana, and Mississippi. Louisiana and Arkansas lie above (west of) the river and
Mississippi is below (east of) the river. This region is characterized by rich farmland
(purple) where a variety of crops are grown. The green regions bordering the river are
undeveloped forested areas. The river is the black band that curves across the image from
the top right-hand corner. The river flows north to south.
1. Interpret the image and discuss the geologic history of this section of the river.
2. Identify where erosion and deposition are occurring along the stream channel and
label those locations E (erosion) and D (deposition) on the blank map on the left of
the image.
3. Use the blank map to draw an earlier course of the channel.
4. Describe how velocity and depth change between points X and Y on the image, and
plot how you expect velocity and depth to vary from X to Y on the graphs provided.
Checkpoint 11.16, p. 309 (Not Required, not Extra Credit)
#16: Create a concept map that links together the components of erosion, transportation,
and deposition in a stream channel.
Checkpoint 11.17, p. 311
#17: List five factors that influence flooding. Use one sentence to briefly describe the role
of each factor in flooding.
Checkpoint 11.18, p. 312
#18: Four stream gauging station locations (A, B, C, D) are shown on the accompanying
map. Assuming the bedrock and topography are similar for each stream system, predict
which station will record the greatest discharge.
a) Station A
b) Station B
c) Station C d) Station D
Checkpoint 11.19, p. 313 (Required, all classes…not as hard as it looks, example is
given on how to calculate RI…graph is done! So only have to interpret graph)
#19: Flood Recurrence Interval: Mississippi River, Keokuk
The following table presents peak flow data for the Mississippi River at Keokuk, Iowa,
1943-1992. This data set ends the year prior to the 1993 Mississippi River flood. We will
use these data to estimate the recurrence interval for the 1993 flood event.
1. Complete the table below by calculating the remaining recurrence intervals (RI) for
the flood events of 1965, 1969, 1976, and 1972 using the formula RI = (N + 1) / rank
where N = number of readings (49) and rank = order of readings (largest = 1; smallest
= 49). For example, the RI for 1960 is ([49 + 1] / 3) = 16.7.
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
25
30
40
49
Date
1973
1965
1960
1986
1951
1974
1979
1944
1952
1969
1975
1947
1986
1948
1982
1962
1983
1946
1967
1976
1972
1954
1970
1977
Discharge (ft3/sec)
344,000
327,000
289,500
268,000
265,100
260,000
257,000
256,000
253,800
253,000
252,000
245,700
241,000
233,600
225,000
224,100
224,000
223,300
221,200
214,000
192,000
181,400
140,000
79,800
RI
50
16.7
12.5
10
8.3
7.1
6.2
5.5
4.5
4.2
3.8
3.6
3.3
3.1
2.9
2.8
2.6
1.67
1.25
1.02
2. a. Plot the discharge versus recurrence interval (RI) on the graph grid provided. Draw
a straight line through the plotted points with RI values of 2 or more and estimate the
size of 100-year and 500-year floods for this gauging station.
b. What is the estimated discharge for a 100-year flood at this gaging station?
3. Compare the predicted flood discharge (above) against the discharge of the 1993
Great Mississippi flood (446,000 ft3/sec). How frequently do floods of this magnitude
occur at this site?
Checkpoint 11.20, p. 314 (extra credit, all classes)
#20: An analysis of flood data in metropolitan areas over the last century suggests that
floods caused by similar volumes of precipitation are actually larger and more
devastating today than in the past, despite advances in flood monitoring. Provide some
potential explanations for this apparent paradox.
Checkpoint 11.21, p. 314 (Not required, Not extra Credit)
#21: List and briefly explain four economic consequences of flooding.
Checkpoint 11.22, p. 317: Flood Control Defining Matrix
#22: Complete the following table by placing check marks in the appropriate columns to
identify whether the characteristics listed at the left represent prevention or adjustment
measures for flooding. One characteristic has been completed as an example.
Characteristic
Levee is constructed
Newspaper publishes flood evacuation route
Flood control by . . .
prevention

adjustment
New housing developments are elevated on pilings
above ground
Dredging removes sediment from streams
Flood zone maps are available in local library
Buildings are relocated outside of flood zone
Dam is constructed upstream from the community
Zoning regulations are enacted to prevent new
construction in floodplain
Checkpoint 11.23, p. 317: Community Flood Rating System Activities (Required all
classes…Notebook for online classes)
#23: The National Flood Insurance Program (NFIP) developed a community rating
system (CRS) to encourage additional community activities that would reduce flood
losses. One goal of the program is to reduce the money spent by the NFIP to help cities
recover from floods. The CRS evaluates 18 potential community activities that may
contribute to better management of the floodplain. For each activity a maximum number
of points can be awarded depending on its potential to reduce flooding costs. Points can
range from a low of 66 to a high of 3,200. We have listed six of the activities, along with
six scores. Predict which activity matches with which score by drawing lines from the
activity column to the points’ column. Write justifications for your choices.
Checkpoint 11.24, p. 318: Flood Risk Rubric(Not Required, Not Extra Credit)
#24: Several states in the Ohio River valley have a history of extensive flooding.
Following graduation, you find yourself working for a state legislator who is part of a
multi-state task force seeking federal funding for flood protection for communities along
a designated river corridor. The corridor stretches along the Ohio River from its source in
Pittsburgh to its mouth in southern Illinois. The legislator asks you to be on a team to
identify the key factors that contribute to flooding along the Ohio River. She requests that
you make a list of factors and develop a scoring scheme that can be applied to rank
locations in terms of future flood risk.
1. Your team is charged to create an evaluation rubric to assess the relative risk of
danger from future flooding. You must find a method of ranking the risk of potential
harm from each flood event. Consider what factors would contribute to the loss of
lives and high damage costs associated with flooding.
2. Complete your evaluation rubric by filling in the blanks on the accompanying table.
Your rubric will be applied to several cities along the river, and the three that score
the highest will receive funds to develop a flood mitigation plan. One factor is
provided as an example. Identify at least five more, and determine the low-,
intermediate-, and high-risk values for each one.
3. After completing the rubric, your team is asked to double the score of the most
important factor. Which do they choose? Why? Explain their choice. Keep in mind
that some factors, while important, may not show much change within a region.
Flood Risk Rubric
Factors
Average annual
rainfall
Low Risk
Moderate Risk
High Risk
(1 point)
(2 points)
(3 points)
Low
Intermediate
High
Less than 75
cm/year
75-125 cm/year
More than 125
cm/year
Streams and Floods Concept Map (not required, not extra credit)
#25: Complete the following concept map to evaluate your understanding of the
interactions between the Earth system and streams and floods. Label as many interactions
as you can, using the information from this chapter.
A
B
C
D
E
F
G
H
I
J
K
L
Rainfall over the ocean
Transpiration of plants