BirdSO Mini 2022 • Division B
Dynamic Planet
Instructions:
-
You have 50 minutes to complete this test.
You may use a binder, but this test is not open internet. It is recommended that you have a
calculator.
This test is worth 128 points. Try to complete as much of the event as possible.
There are 5 sections of varying length, format, and difficulty. It is recommended to look
through all sections.
The point value of “select all that apply” questions is not necessarily equal to the number of
correct answers.
Show work for calculations and include units where necessary.
Tiebreakers are marked as [TB #] in the order that they will be used to break ties.
Section 1 (64 points)
1) Which of the following best describes the
role of clay-rich material in a confined aquifer
system?
A. Interspersed in the aquifer, uniformly
lowering overall permeability
B. Is saturated with water, acting as the
aquifer
C. Underlies the aquifer, allowing it to
sit above an unsaturated region
D. Becomes the upper bound of an
aquifer, preventing upward flow
2) A well located along the coast supplies
groundwater to irrigate agricultural fields. If
the fields are threatened with saltwater
intrusion, what additional well should be
installed in order to protect the supply of
freshwater, and where?
A. Recharge well between the ocean
and the well
B. Recharge well on the opposite side of
the well from the ocean
C. Supply well between the ocean and
the well
D. Supply well on the opposite side of
the well from the ocean
3) A particular saline lake varies in water
level with precipitation. How is the
relationship between salinity and lake level
best described?
A.
B.
C.
D.
Salinity rises with rising lake levels.
Salinity falls with rising lake levels.
Salinity remains about constant.
Salinity fluctuates regardless of lake
level.
4) A water management team is searching for
a location for artificial groundwater recharge
by means of injection. What environment
would be most suitable?
A.
B.
C.
D.
Slightly offshore
Above an ancient lake
An alluvial fan
A mountain range
5) How does the location of a nick point tend
to change over time?
A.
B.
C.
D.
Moves upstream
Moves downstream
Moves from side to side
Moves straight down
6) A flood recurrence interval of 50 years
means that a flood of the same or greater
size:
A. Will occur within 50 years.
B. Occurs every 50 years.
C. Has a 2% chance of occurring in one
year.
D. Has a 2% chance of occurring in 50
years.
7) [TB 1] As sediment is transported down a
stream, sediments tend to become:
A.
B.
C.
D.
Rounder and more sorted.
More angular and more sorted.
Rounder and less sorted.
More angular and less sorted.
8) Which of the following is always true
about a particular porous material? Check all
that apply.
A. It is highly permeable by
groundwater.
B. Its porosity is closer to 1 than a less
porous material.
C. It is less dense than all materials with
lower porosities.
D. Its pore spaces are approximately
uniform in size.
9) Some rivers have a light brown to cream
color because of:
A. A high concentration of dissolved
minerals.
B. A large amount of particulates
suspended in water.
C. Light-colored gravels rolling along
the river bed.
D. Less-dense material floating on the
surface.
10) Stream order is a measure that reflects
what stream characteristics? Check all that
apply.
A. Relative size within a watershed
B. Size as compared with streams from
other watersheds
C. Amount of tributaries upstream
D. Amount of distributaries
downstream
E. The maturity of stream branches
F. The maturity of the largest stream
11) The contamination of groundwater with
road de-icing salt is an example of:
A. Point source pollution because road
de-icers are widely applied to areas.
B. Point source pollution because road
de-icers percolate directly into
groundwater.
C. Point source pollution because the
source of salt is readily identifiable.
D. Non-point source pollution because
road de-icers are widely applied to
areas.
E. Non-point source pollution because
road de-icers percolate directly into
groundwater.
F. Non-point source pollution because
the source of salt is readily
identifiable.
12) In the northern hemisphere, what time in
the year would one expect the thermocline of
a lake to be the strongest?
A.
B.
C.
D.
January-February
April-May
July-August
October-November
15) What distinguishing feature of a certain
type of stream does the name “Sinking
Creek” of the river in the lower left describe?
A. Surface flow descends underground
B. Sinkholes forming beneath the
stream
C. Water flow through a solution valley
D. Decreasing elevation downstream
16) The permeability of the landscape is
largely controlled by which of the following
reactions?
13) What direction does groundwater most
likely move? Assume north is up on the page.
A.
B.
C.
D.
NE
NW
SE
SW
14) In this map, what map symbol indicates
the presence of sinkholes?
A.
B.
C.
D.
A
B
C
D
A. NaCl → Na+ + ClB. CaSiO3 + 2CO2 + 3H2O →
Ca2+ + 2HCO3- + H4SiO4
C. KAlSi3O8 + 8H2O →
K+ + Al(OH)4- + 3H4SiO4
D. CaCO3 + H2CO3 → Ca2+ + 2HCO317) [TB 7] Briefly describe two reasons why
agriculture is difficult environments such as
the one depicted. (4 pts)
18) A storm produces significant amounts of
runoff in the watershed above. What might
one expect a storm hydrograph from the very
bottom of the watershed to look like?
A.
B.
C.
D.
A single peak with a leftward tail
A single peak with a rightward tail
Two distinct but similar peaks
Two peaks of different heights
19) Which of the following is true of surface
flow within the watershed, outside of the
streams shown?
A. At every point, water takes the
shortest path to the nearest stream
shown.
B. All water flows as sheets down the
watershed surface into the streams.
C. Water flows through streams smaller
than those shown.
D. Water flow begins mostly at the
watershed boundaries.
Refer to the figure above for questions
20-22. The figure above shows two cross
sections (left) from a river (right).
20) Which cross section corresponds to the
red line on the river?
A. Cross section I
B. Cross section II
C. Either cross section I or II, depending
on flow direction
D. Cannot be determined with the
information given
21) In cross section II, the leftward portion of
the channel bed is being:
A. Deposited with sediment and shifting
to the right.
B. Deposited with sediment and shifting
to the left.
C. Eroded by running water and shifting
to the right.
D. Eroded by running water and shifting
to the left.
22. a) In cross section I, the highest flow
velocity occurs:
A.
B.
C.
D.
To the right, on the surface.
To the left, on the surface.
To the right, beneath the surface.
To the left, beneath the surface.
22. b) Given the discharge of the river and
the scale of cross section I, briefly explain
how you would calculate the average velocity
of water flow through cross section I. (3 pts)
25) Consider the following map view of a
river (arrow shows flow direction) with
labeled points X, Y, and Z. Four possible
profiles are shown.
23) Rank the average particle size of the
following stream loads from smallest to
largest.
1 - bed load
2 - suspended load
3 - dissolved load
A.
B.
C.
D.
E.
F.
1, 2, 3
1, 3, 2
2, 1, 3
2, 3, 1
3, 1, 2
3, 2, 1
24) Which of the following graphs, if any, best
shows the relationship between the radius of
sediment particles versus increasing depth in
the middle of a lake?
A.
B.
C.
D.
E.
F.
A
B
C
D
E
No distinct relationship; lake deposits
are often poorly sorted
26) Which topographic profile is the most
accurate? Assume uniform discharge in the
river.
A.
B.
C.
D.
A
B
C
D
27) Consider a hypothetical drainage system
in which all first-order tributaries have
identical discharges of 100 m3/s. Which best
describes the discharge at the start of a
third-order stream (i.e., the point of a
third-order stream closest upstream)? (Use
Strahler stream order)
A.
B.
C.
D.
E.
F.
Equal to 300 m3/s
At least 300 m3/s
At most 300 m3/s
Equal to 400 m3/s
At least 400 m3/s
At most 400 m3/s
28) Which of these conditions is most likely
to result in a decrease in delta size?
A. Increased upstream precipitation and
regional uplift
B. Increased upstream precipitation and
regional subsidence
C. Decreased upstream precipitation
and regional uplift
D. Decreased upstream precipitation
and regional subsidence
For questions 29-31, refer to the following
topographic map. Assume the top of the map
is north.
29) What type of stream is featured in the
map?
A.
B.
C.
D.
E.
Perennial stream
Disappearing stream
Intermittent stream
Underground stream
Rapids
30) What type of wetland, if any, is featured
in the map?
A. Submerged marsh or swamp
B. Wooded marsh or swamp
C. Marsh or swamp (not submerged or
wooded)
D. No wetlands are featured
31) What is the most likely direction of
groundwater flow within the green boxed
area?
A.
B.
C.
D.
Towards the north
Towards the east
Towards the south
Towards the west
32) Some relatively sinuous river systems
experience a sudden decrease in sinuosity.
What is the most likely cause for this
occurrence?
A. Sudden changes in discharge, such as
flooding
B. Earthquakes and tectonic events,
resulting in sag pond formation
C. Landslides blocking river flow,
forming a natural dam
D. Formation of oxbow lakes due to
streamflow changes
E. Tendency for more mature streams to
straighten
33) Which of the following sediment types
would have the greatest porosity to
permeability ratio (porosity / permeability)?
A.
B.
C.
D.
E.
Cobbles
Clay
Silt
Sand
Gravel
34) Which of the following correctly lists
water reservoirs in order of increasing
percentage of Earth’s total water?
For questions 36 and 37, refer to the
following satellite image labeled with two
locations, X and Y.
A. Glaciers and ice caps < Lakes < the
Atmosphere < Oceans
B. Glaciers and ice caps < the
Atmosphere < Lakes < Oceans
C. Lakes < the Atmosphere < Glaciers
and ice caps < Oceans
D. Lakes < Glaciers and ice caps < the
Atmosphere < Oceans
E. The Atmosphere < Lakes < Glaciers
and ice caps < Oceans
The Atmosphere < Glaciers and ice
caps < Lakes < Oceans
35) Which of the following correctly lists
water reservoirs in order of increasing
percentage of Earth’s fresh water?
A. Rivers and streams < Lakes <
Permafrost < Glaciers and ice caps
B. Rivers and streams < Permafrost <
Lakes < Glaciers and ice caps
C. Lakes < Rivers and streams <
Permafrost < Glaciers and ice caps
D. Lakes < Permafrost < Rivers and
streams < Glaciers and ice caps
E. Permafrost < Rivers and streams <
Lakes < Glaciers and ice caps
F. Permafrost < Lakes < Rivers and
streams < Glaciers and ice caps
36) Location X is at a(n) ___ elevation
compared to Location Y.
A.
B.
C.
D.
Higher
Lower
Equal
Cannot be determined
37) Which of the following statements are
true regarding the process occurring near
Location X? (2 pts)
A. The process shortens the stream
channel
B. The process lengthens the stream
channel
C. The process is dominated by erosion
D. The process is dominated by
deposition
38) Hack’s law states that the length of the
longest stream in a basin can be
approximated by L = CAh, where L is the
length of the longest stream, A is the area of
the basin, and C is some constant. Assuming
the exponent h to be 0.6, how many times its
original length would the longest stream in a
basin be if the area of the basin doubled?
A.
B.
C.
D.
0.660
0.737
1.516
2.000
39) Large forest fires can impact a region’s
hydrology significantly. Select all of the
following statements that are true regarding
their impacts. (2 pts)
A. Reduction in overland flow during
heavy rain events
B. Reduction in soil moisture
C. Reduction in infiltration capacity
D. Reduction in transpiration rate
40) A well begins pumping groundwater at a
uniform rate q1 for time t. If the pumping rate
decreases to a new uniform rate q2 < q1 for
another time interval t, which of these best
describes what will happen to the cone of
depression? (Assume no recharge and
uniform soil.)
A. An increase in its depth and a
decrease in its slope
B. An increase in its depth and a
decrease in its radius
C. An increase in its slope and a
decrease in its depth
D. An increase in its radius and a
decrease in its depth
41) Which of the following correctly matches
the lake to its type?
A.
B.
C.
D.
Lake Baikal, tectonic lake
Lake Agassiz, glacial lake
Crater Lake, volcanic lake
All of the above
42) Select all of the following statements that
are true regarding the hydrograph for a
region after it is urbanized. (2 pts)
A. A larger proportion of rainwater
infiltrates the ground compared to
pre-urbanization
B. A smaller proportion of rainwater
infiltrates the ground compared to
pre-urbanization
C. The peak discharge after rainfall is
greater compared to peak discharge
pre-urbanization
D. The peak discharge after rainfall is
lower compared to peak discharge
pre-urbanization
E. The lag time between rainfall and
discharge is longer compared to the
lag time pre-urbanization
F. The lag time between rainfall and
discharge is shorter compared to the
lag time pre-urbanization
43) A chemical spill happens instantaneously
in a localized region marked by the X on the
map. The edge of the plume reaches site B at
t = 10 min after the spill. Select all of the
following statements which are likely true.
(Note: A10 = concentration of pollutant at site
A at time t = 10 min) (2 pts)
45) Consider the data table below with wells
and the height of the piezometric surface in
meters above sea level. Each well is located
at 125 m above sea level.
Well
A
B
C
D
Height
150
100
150
100
Confined
aquifer?
Yes
Yes
No
No
Which well is considered an artesian well?
A.
B.
C.
D.
E.
F.
A10 > B10
A10 = B10
A10 < B10
A10 > A30
A10 = A30
A10 < A30
44) Which of these can be generally assumed
about the rate of pollutant transport at 10 m
below the surface, v10, and at 50 m below the
surface, v50?
A.
B.
C.
D.
v10 > v50
v10 = v50
v10 < v50
Inconclusive; the rates vary widely by
region
A.
B.
C.
D.
A
B
C
D
46) The table below describes the vegetation
found at three locations.
Location
Vegetation
X
cypress trees, buttonbush
shrubs, cattails
Y
sphagnum moss, water
chestnut sedge, pitcher plants
Z
sawgrass, cattails, papyrus
sedge
Which of the following correctly classifies
the three locations?
A.
B.
C.
D.
E.
F.
X - bog, Y - marsh, Z - swamp
X - bog, Y - swamp, Z - marsh
X - marsh, Y - bog, Z - swamp
X - marsh, Y - swamp, Z - bog
X - swamp, Y - bog, Z - marsh
X - swamp, Y - marsh, Z - bog
47) Select all of the following statements that
are true regarding bogs. (2 pts)
A. Bogs derive the majority of their
water from surface water
B. Bogs derive the majority of their
water from groundwater
C. Water flowing from bogs tends to be
brown due to high peat tannin
concentrations
D. Bogs are eutrophic
E. Bogs are oligotrophic
F. Bogs are ombrotrophic
48) Select all of the following statements that
are true regarding freshwater marshes. (2
pts)
A. They are often found in high
elevation areas
B. They are characterized by moist,
well-oxygenated soils
C. They reduce the variability of
adjacent streamflow
D. Some freshwater marshes are subject
to cyclic changes in water levels
E. Diversion of water by artificial canals
can lead to their decline
49) Select all of the following statements that
are true regarding the feature in this image.
(2 pts)
A. The feature forms when the soil
temperature remains below 0 °C
B. The feature forms when the soil
temperature remains below 32 °C
C. The open system type of this
structure is found in areas with a
substantial groundwater source
D. The closed system type of this
structure is found in areas with a
substantial groundwater source
E. The high specific heat of water is
directly related to the formation of
these features
F. The expansion of water at low
temperatures is directly related to
the formation of these features
50) Which of the following statements
regarding speleothems is incorrect?
A. Stalactites hang from the ceilings of
caverns
B. Caverns with speleothems occur
within the saturated zone
C. Columns form when a stalagmite
combines with a stalactite
D. Stalagmites have a hollow structure
E. None of the above (all statements are
correct)
51) Which of the following incorrectly
matches the fluvial terrace type to its
description?
A. Strath terraces form when a stream
downcuts through bedrock
B. Unpaired terraces are terraces that
exist on opposite sides of a river but
are at the same elevation
C. Nested fill terraces form when a
previously filled valley is eroded and
refilled with less sediment
D. Fill terraces form when a valley is
filled with river sediment
52) Which of the following pollution sources
can be considered geogenic?
A. Road salt causing high chloride
concentrations in water bodies
B. Excessive fertilizer use causing high
nitrate concentrations
C. Uranium in bedrock decaying to
release radon
D. Leachate from landfills seeping into
aquifers
E. Improperly designed septic tanks
allowing bacteria to enter
groundwater
Section 2 (12 points)
1) True/False: Water flowing in the
hyporheic zone of a stream channel
tends to flow faster than it does in the
open channel.
2) True/False: For an ephemeral stream,
the water table is below the stream
channel.
3) True/False: In a region where a river
transitions from flowing over more
resistant bedrock to less resistant
bedrock, a nickpoint is likely to form
after some time.
4) True/False: During a flood, the
competence of a stream increases
while its capacity remains the same.
5) True/False: For a meandering stream,
the thalweg is closer (in terms of
horizontal distance) to the cut bank
than the point bar.
6) True/False: In a straight channel
stream, the greatest flow velocity in a
stream tends to be near the bed of
the channel.
7) True/False: Potholes are often
formed in the sections of a stream
that exhibit laminar flow.
8) True/False: The implementation of
flood-control dams would cause the
floodplain to erode.
9) True/False: As stream velocity
increases, sand is usually the first to
be eroded before clay.
10) True/False: A river system in dynamic
equilibrium means that it is not
subject to disturbances or
perturbations that may affect its flow.
11) [TB 8] A student calculates the
sinuosity of a certain stream to be
0.45. How can one immediately tell
that this value is unreasonable? Why
is this answer not physically possible?
(2 pts)
Section 3 (6 points)
The false-color image of Fresno, California shows the normalized difference vegetation index
(NDVI), where higher values (in green) signify more healthy and abundant vegetation.
1) True/False: Areas with higher NDVI values generally yield more runoff than areas with
lower NDVI.
2) True/False: The green in the image indicates higher NDVI as a result of more rainfall.
3) True/False: A tends to be warmer than B because solar energy is stored as latent heat in A
more than B.
Consider a high precipitation event.
4) True/False: Total runoff per unit area is greater in A than B.
5) [TB 3] True/False: Assuming A and B belong in the same drainage basin, a graph of river
discharge over time would show a peak in discharge sooner after peak rainfall if B were
more similar to A.
6) True/False: If A and B were the only sources of runoff into a river flowing to the left, the
discharge-time graph would have a steeper ascending than descending limb.
Section 4 (23 points)
Above: topographic map of the Tahoma Creek drainage in Mount Rainier National Park.
1) Approximate the gradient, in ft/km, of Tahoma Creek. (3 pts)
2) What type of drainage pattern would most likely surround Mt. Rainier? (1 pt)
A.
B.
C.
D.
Rectangular
Dendritic
Radial
Parallel
3) What channel type (braided, meandering, straight) does Tahoma Creek have? Justify your
answer. (3 pts)
4) Which of the following curves below most likely represents the discharge of Tahoma Creek over
a year? (2 pts)
5) Over a year, Tahoma Creek has an average discharge of 25 cubic meters per second. What
volume of water is discharged by Tahoma Creek in that year? (2 pts)
A.
B.
C.
D.
E.
9.1 * 104 cubic meters
1.3 * 107 cubic meters
3.9 * 107 cubic meters
7.9 * 108 cubic meters
9.5 * 108 cubic meters
The figure above shows the debris flow discharge (solid line) and the water-only discharge (dashed
line) of Tahoma Creek during a flood. The x axis is the elapsed time in minutes.
6) When discharge is graphed versus time (like the graph above), what property of the graph
represents the volume discharged over that time? (Hint: consider the problem above where we had a
constant discharge. If you graphed it versus time, what would represent the volume?) (2 pts)
A.
B.
C.
D.
The maximum discharge rate multiplied by the elapsed time
The minimum discharge rate multiplied by the elapsed time
The average slope of the discharge rate versus time graph
The area under the discharge rate versus time graph
7) [TB 2] Estimate the volume of water, in cubic meters, discharged by the creek during this flood.
(5 pts)
8) [TB 4] Estimate the mass of sediment, in kg, discharged by the creek during this flood if the
average density of the sediment is 2650 kg/m3. (5 pts)
Section 5 (23 points)
The Aral Sea is a lake in Central Asia. It used to be the fourth largest lake in the world by volume,
but due to water diversion for cotton irrigation, it has mostly dried up.
Shown above is a map of the Aral Sea drainage basin. The red line denotes the boundary of the
drainage basin, while the two blue lines denote the Syr Darya and Amu Darya, the two major rivers
that flow into the Aral Sea.
1) True/False: The Aral Sea occupies the base level elevation of the drainage basin. (1 pt)
2) Select all of the following statements that must be true about A, B, and C. (3 pts)
A.
B.
C.
D.
E.
F.
B is higher in elevation than C
It is impossible for water to flow from A to B
A is higher in elevation than C
C is higher in elevation than A
There is not enough information to decide whether A or C is higher
It is impossible for water to flow from A to C
Let’s consider the water mass balance of the Aral Sea. Given the following parameters:
P (precipitation rate, in m/yr)
E (evaporation rate, in m/yr)
S (the surface area of the lake, in m2)
I (river inflow rate, in m3/yr)
G (groundwater inflow rate, in m3/yr)
O (river outflow rate, in m3/yr).
3) [TB 6] Relate the variables above in an equation if the volume of the Aral Sea stays constant
over time. (Hint: consider the drainage basin. What is O?) (3 pts)
4) Relate the given variables in an equation if the volume of the Aral Sea is decreasing over time at
a constant rate L. (3 pts)
Before the Aral Sea dried up, it was a large, salty lake. Its thermal structure was determined by
mixing, which was driven by wind and thermohaline convection (similar to the ocean!). Let’s
explore this thermohaline mixing. (The next four questions are 1 pt each)
5) [TB 5] As temperature increases, density __[increases/decreases/it depends on the
temperature]__.
6) As salinity increases, density __[increases/decreases/it depends on the salinity]__.
7) Which of the following must be true for density-driven mixing?
A. The surface density is less than subsurface density
B. The surface density is greater than subsurface density
C. The surface density is equal to subsurface density
8) In a typical freshwater dimictic lake, mixing occurs in ___ and ___.
A.
B.
C.
D.
Summer, winter
Spring, summer
Spring, autumn
Autumn, winter
9) For each of the seasons you selected, briefly explain why the mixing occurs. (Hint: consider the
effect of temperature on density) (3 pts)
10) But since the Aral Sea is salty, its mixing is also affected by salinity changes. One salinity-driven
mixing mechanism occurs in winter, when ice forms. Briefly explain how ice formation can lead to
mixing. (2 pts)
11) Another salinity-driven mixing mechanism occurs in summer, when the warm, dry air of the
steppe causes significant evaporation. Briefly explain how this can lead to mixing. (2 pts)
12) Select all of the following changes that occurred as the Aral Sea shrunk. (2 pts)
A.
B.
C.
D.
Regional summers got hotter while winters got colder
Its water got fresher
It became stably stratified and did not mix at any point of the year
The temperature required for ice formation decreased 3