Deck 15: Running Water

Question 1

________ make up the suspended loads of most rivers and streams.

A)Dissolved ions and fine sand
B)Dissolved salts
C)Silt and clay-sized, detrital grains
D)Coarse sand and gravel that move during floods

Answer 1

C

Question 2

In a typical stream, the suspended sediment load ________.

A)decreases greatly during floods
B)usually includes fine sand, silt, and clay
C)saltates along the bottom
D)weighs less than its total dissolved constituents

Answer 2

B

Question 3

________ is not part of the hydrologic cycle.

A)Water evaporating from a lake
B)Water infiltrating into the soil and bedrock
C)Calcium carbonate dissolving in or precipitating from soil water and groundwater
D)Water moving into creeks and streams following a rainstorm

Answer 3

C

Question 4

The ________ river has the largest discharge in North America.

A)Columbia
B)Mackenzie
C)Yukon
D)Mississippi

Question 5

What is the drop in water surface elevation divided by the distance the water flows?

A)stream discharge
B)hydraulic capacity
C)hydrologic resistance
D)stream gradient

Question 6

________ describes the particle transport mode in streams intermediate between suspension and rolling along the bottom?

A)Siltation
B)Alluviation
C)Skippity-doo-dah
D)Saltation

Question 7

________ is the product of the average flow velocity and the area of the channel cross section (velocity × area).

A)Runoff gradient
B)Stream discharge
C)Hydrocapacity
D)Stream load factor

Question 8

The ________ river has the largest discharge of any in the world.

A)Nile
B)Mississippi
C)Congo
D)Amazon

Question 9

________ are components of the hydrologic cycle that release water vapour directly to the atmosphere.

A)Runoff and infiltration
B)Evaporation and transpiration
C)Precipitation and runoff
D)Discharge and transportation

Question 10

Which one of the following does not apply to stream turbulence and average velocity?

A)channel shape; bed roughness
B)laminar flow; dissolved load
C)discharge; stream gradient
D)stream gradient; channel roughness

Question 11

________ generally constitutes the highest percentage of the annual sediment load moved by a stream.

A)Bed load
B)Dissolved load
C)Suspended load
D)Saltation load

Question 12

Which of the following is the correct definition of stream gradient?

A)the distance travelled by water in a channel times a drop in elevation
B)the drop in elevation of a stream divided by the distance the water travels
C)the water pressure at the bottom of the stream divided by the stream's width
D)the increase in discharge of a stream per unit drop in elevation

Question 13

________ describes the maximum particulate size that a stream can transport.

A)Capacity
B)Discharge
C)Competence
D)Hydro-load factor

Question 14

Which one of the following is true concerning a major river system?

A)Upstream tributaries generally have lower gradients than the major river.
B)Channel bed roughness and turbulence generally increase downstream.
C)Upstream tributaries generally have higher competencies than the major river.
D)Discharge decreases below junctions with perennial tributaries.

Question 15

The greatest erosion and sediment transport in rivers happens ________.

A)near the mouth where the discharge is the greatest
B)during floods because capacity and competence are at their maxima
C)at ordinary discharge but at particular locations where the gradient decreases
D)during winter freeze up because of velocity changes below the ice

Question 16

A stream begins at an elevation of 200 metres and flows a distance of 400 kilometres to the ocean.What is the average gradient?

A)2 m/km
B)2 km/m
C)0)5 m/km
D)0)5 km/in

Question 17

________ describes the amount of water flowing past a certain point at any given time.

A)Capacity
B)Discharge
C)Competence
D)Hydro-load factor

Question 18

________ describes the maximum solid particulate sediment load transported by a stream.

A)Capacity
B)Discharge
C)Competence
D)Hydro-load factor

Question 19

A natural, meandering, river channel is modified into a more or less straight and smooth, canal-like channel.Which of the following statements is correct?

A)The natural channel had a lower gradient and less friction than the modified channel.
B)The straight channel has a higher gradient and more friction than the natural channel.
C)The natural channel had a lower gradient and higher friction than the straight channel.
D)There was no change in gradient or friction.

Question 20

The ________ describes the movement of water through Earth's hydrosphere.

A)aqualytic cycle
B)aquatic cycle
C)precipitation cycle
D)hydrologic cycle

Question 21

A(n)________ is a curved lake on a low gradient floodplain formed from the abandoned channel after a meander loop is cut off.

A)gooseneck
B)snakebelly
C)drooping johnson
D)oxbow

Question 22

In the absence of cutoff, how does a river meander loop behave over time?

A)The gradient is raised as the loop lengthens, and the channel migrates toward the cut or inner bank of the loop.
B)The gradient is raised as the loop shortens, and the channel migrates away from the cut or outer bank of the loop.
C)The gradient is lowered as the channel lengthens and migrates toward the cut or outer bank of the loop.
D)The gradient is lowered as the loop shortens, and the channel migrates toward the shallow inner bank of the loop.

Question 23

Which of the following locations is a likely place to find a braided stream?

A)flowing across a stream delta
B)flowing across a low gradient landscape
C)flowing through a karst region
D)flowing from the terminus of a glacier

Question 24

A ________ stream consists of a complex network of converging and diverging channels that weave around channel bars.

A)Straight channel
B)Meandering stream
C)Braided stream
D)Bedrock channel

Question 25

Incised meanders are evidence for what sequence of geologic events?

A)Land uplift was followed by stream downcutting.
B)Lateral cutting by streams was followed by subsidence of the land.
C)A sea level rise was followed by stream downcutting.
D)Stream downcutting was followed by a rise in base level.

Question 26

A dam and reservoir are constructed on a graded river.What will happen?

A)deposition upstream from the dam; channel downcutting below
B)channel downcutting upstream from the dam; deposition below
C)deposition upstream and downstream from the dam
D)channel downcutting upstream and downstream from the dam

Question 27

________ are characteristics of downcutting streams and a youthful stage of valley evolution.

A)Rapids and whitewater
B)Wide floodplains
C)U-shaped, cross-valley profiles
D)Meandering channels and natural levees

Question 28

Which statement below best describes how narrow valleys form?

A)Stream water dissolves the bedrock along a narrow swath of soluble bedrock.
B)Stream cuts vertically along soft fault gouge.
C)Streams tend to flow down abandoned mine shafts.
D)Stream cuts vertically, but valley sides cave in due to weathering and mass wasting.

Question 29

Which one of the following best fits with floodplain widening?

A)youthful stream; downcutting and waterfall retreat
B)old age stream; rapid erosion of a delta
C)mature stream; lateral cutting and point bar deposition
D)stream rejuvenation; downcutting and meandering

Question 30

Fraser River in the Fraser Plateau meanders in a deep, narrow canyon and has no floodplain.How could this happen?

A)Original, high gradient, youthful stream continued to downcut as the land rose.
B)Original, low gradient, old age stream downcut as the land gradually rose.
C)As sea level dropped, the original youthful stream matured into an old-age stream.
D)As the Fraser Plateau rose, the original, new-age stream became wiser.

Question 31

Which one of the following statements is true concerning natural levees?

A)Depositional features formed at times of low discharge.
B)Mostly fine sand and silt build up during overbank floods.
C)Erosional features are left behind when meander cutoff occurs.
D)They form the high, steep banks of a downcutting stream.

Question 32

If you found yourself "up the yazoo without a paddle" you'd likely be ________.

A)following the wrong distributary upstream, never to intersect the main channel
B)going up a low capacity parallel tributary on the other side of the levee from the main channel
C)in a meander cutoff oxbow lake across the cutbank from the main channel
D)vainly wishing that you had read the textbook a little more closely

Question 33

Which of the following features characterize wide streams and valleys?

A)natural levees; broad floodplains
B)rapids; channel bed potholes
C)waterfalls; entrenched meanders
D)V-shaped valley cross-sections

Question 34

________ is an abandoned, cutoff, meander loop.

A)A horsetail
B)An oxbow
C)A yazoo
D)A gatorback

Question 35

Which one of the following statements is true concerning natural levees?

A)depositional features formed at times of low discharge
B)mostly fine sand and silt that build up during floods
C)erosional features left behind when meander cutoff occurs
D)form the high, steep banks of a downcutting stream

Question 36

Which of the following statements is false about an anastomosed stream?

A)resemble braided streams
B)have deep, interwoven, multiple channels
C)channels shift frequently
D)channels are separated by stable vegetated islands

Question 37

Which of the following must result in a lower base level for rivers and streams?

A)sea level drops; land subsides to below sea level as in rifts like the Dead Sea and Death Valley
B)sea level falls; land rises
C)sea level rises: land subsides
D)sea level rises; land rises

Question 38

Which of the following statements is false about braided streams?

A)Sand and gravel bars between channels are covered with vegetation.
B)Braided streams comprise complex networks of converging and diverging channels.
C)Braided channels are temporary and shift frequently.
D)Sand and gravel bars between channels are unstable.

Question 39

Which of the following is not one of the three basic types of stream systems?

A)Annastomosed
B)Meandering
C)Braided
D)Bedrock gorge

Question 40

Where is erosion concentrated along a meandering stream?

A)on the straight channel segments that connect the meander loops
B)on the outer parts of the meander loops or bends
C)at the unconsolidated point bars
D)on the inner banks of the meander loops

Question 41

Which one of the following statements correctly describes how stream terraces can form?

A)Base level drops; the stream aggrades its channel, and the former floodplain is left below the present elevation of the stream.
B)A temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.
C)Base level rises; the stream downcuts, and the old floodplain is left well above the elevation of the present-day channel.
D)A temporary base level is eliminated; the stream builds its channel upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.

Question 42

At the head of a delta, the major channel splits into smaller channels that follow different paths to the sea.These smaller channels are known as ________.

A)endotributaries
B)exotributaries
C)distributaries
D)cotributaries

Question 43

Where would you find clays and silts in delta sediments?

A)bottomset beds
B)distributary channels
C)foreset beds
D)topset beds

Question 44

Which one of the following best describes how urbanization affects small-stream watersheds?

A)Infiltration is reduced; lag time between storms and peak runoff is increased.
B)Infiltration increases slightly; lag time between storms and peak runoff decreases.
C)Infiltration decreases; lag time between storms and peak runoff is shortened.
D)Infiltration and lag time between storms and peak runoff increase.

Question 45

What would cause a river to have a series of terraces lying at different elevations, all above its modern floodplain?

A)agrarian alien visitors in the geologic past constructing paddies
B)deranged drainage patterns
C)incision due to uplift or lowered base level
D)progressive decreases in rainfall in its headwaters

Question 46

Which deposits form during flood stage on a subaerial delta plain?

A)topset beds
B)bottomset beds
C)foreset beds
D)distributary channels

Question 47

Which of the following is not a type of flood?

A)gradual flood
B)regional flood
C)flash flood
D)ice-jam flood

Question 48

Which of the following are not methods of flood control?

A)artificial levees
B)flood-control dams
C)channelization
D)demolishing dams

Question 49

In a ________ drainage pattern that is generally developed in areas underlain by tilted or folded strata, tributary streams flow along outcrop areas of the softer strata.

A)trellis
B)dendritic
C)rectangular
D)radial

Question 50

A ________ stream pattern develops on lands underlain by tilted or folded, alternating hard and soft, sedimentary strata.

A)dendritic
B)radial
C)trellis
D)rectangular

Question 51

A radial drainage pattern would most likely develop ________.

A)on an active, growing volcano
B)in areas underlain by horizontal strata
C)in areas where the bedrock is cut by sets of fractures at right angles
D)in areas of folded and tilted strata with varying resistances to erosion

Question 52

Which one of the following would cause stream rejuvenation?

A)sea level rises
B)a shift from downcutting to lateral cutting
C)the land is uplifted
D)when unstable distributaries in a delta are abandoned

Question 53

How does urbanization (buildings, paving, lawns etc.)affect runoff and infiltration in a small, previously forested, drainage basin?

A)Both decrease.
B)Runoff decreases; infiltration increases.
C)Both increase.
D)Infiltration decreases; runoff increases.

Question 54

A ________ stream pattern is developed only on growing mountains like volcanoes or where the land surface is tectonically doming upward as over intrusions or salt diapirs.

A)radial
B)dendritic
C)boreal
D)trellis

Question 55

At the head of a delta, the major river divides into numerous, smaller channels.What are these smaller channels?

A)outflow channels
B)cutoff chutes
C)intradeltaic rills
D)distributaries

Question 56

Why is a bird-foot delta like that of the present-day Mississippi below New Orleans likely to change naturally toward one with the shape of an equilateral triangle like the upper-case Greek letter delta (?)?

A)Present-day distributaries have higher gradients than potential new ones.
B)Potential, new, major distributary channels have steeper gradients than existing channels.
C)Potential, new, distributary channels have higher gradients, causing downcutting of the existing channels.
D)Increased sediment loads since the mid-19th century have caused the major distributaries to be filled with sand.

Question 57

Where would you expect to find the coarsest particle size in delta sediments?

A)foreset beds
B)bottomset beds
C)distributary channels
D)topset beds

Question 58

A(n)________ stream pattern develops where the same bedrock or regolith layer forms the land surface so that erosion rates are relatively uniform throughout the area.

A)radial
B)trellis
C)elliptical
D)dendritic

Question 59

________ in a delta are essentially cross strata inclined toward deeper water.

A)Backset beds
B)Topset beds
C)Foreset beds
D)Bottomset beds

Question 60

Which of the following statements best characterizes alluvial fans?

A)They develop where a high-gradient stream leaves a narrow mountain valley and deposits on a flat area.
B)They develop where a low-gradient stream leaves a wide valley and deposits in a canyon.
C)They develop where a low-gradient tributary meets the main stream.
D)They develop where a high-gradient tributary splits when it enters a flat area.

Question 61

Evapotranspiration and average stream velocity are both important components of the hydrologic cycle.

Question 62

Most stream valleys are diverse in their forms because they are basically just curious accidents of nature and have little to do with ongoing geologic processes.

Question 63

The hydrologic cycle is off-balance because more liquid is brought in via comets and meteorites each year.

Question 64

For the same discharge, gradient, and channel cross section, a stream with a boulder-strewn bed would be more turbulent than one with a sandy bed.

Question 65

Natural levees are constructed of machine-compacted sand and mud; artificial levees are made of concrete.

Question 66

Floodplains are always depositional and never erosional.

Question 67

The lower Mississippi River has the largest discharge of any river in North America.

Question 68

A V-shaped valley and no floodplain indicate a youthful, downcutting stream.

Question 69

Rapids and waterfalls are characteristic of laterally cutting streams.

Question 70

Point bars are depositional features located along the outer portions of meander bends at the foot of the steep cutbank.

Question 71

Alluvium refers to all solid unconsolidated stream deposits, mainly sand and gravel.

Question 72

Lateral cutting and deposition are important factors in floodplain development.

Question 73

After a meander is cut off, the gradient through the newly formed cutoff is steeper than the gradient along the abandoned meander loop.

Question 74

Potholes are formed by turbulently swirling pebbles and cobbles that abrade the bedrock of the streambed.

Question 75

A stream flowing out from a lake cannot downcut below the water surface elevation of the lake.

Question 76

Stream discharge is defined as the quantity of water flowing past a specific channel location per unit time.

Question 77

Saltation refers to excessive halite falling into a stream and dissolving in it.

Question 78

Most precipitation in land areas originates by transpiration and by evaporation from lakes and rivers.

Question 79

The lowest base level for most streams is sea level.

Question 80

Gradients usually decrease downstream in a major river system.