Geology Chapter 16
What is a floodplain?
A broad strip of land built up by sedimentation on either side of a stream channel and covered with water during a flood
A stream that flows year-round is a(n) perennialBlank 1Blank 1 perennial , Correct Unavailable stream, whereas a(n) intermittentBlank 2Blank 2 intermittent , Correct Unavailable stream does not flow the entire year.
Blank 1: perennial Blank 2: ephemeral or intermittent
Dam
Changes the base level because of sediment buildup
Bed
Choice Material carried on the bottom of a river by pushing, bouncing, rolling, and sliding; usually sand and gravel
Suspended
Clay and silt carried indefinitely above the riverbed
Select the human-caused flooding events from the list of flood causes below.
Dam failure Urbanization
Which of the following physical parameters show an increase from the headwaters to the mouth of a river?
Discharge Channel size Sediment load
What problems are associated with straightened or channelized stream channels?
Downstream flooding Increased erosion downstream Reduced sediment deposition downstream
Select conditions that have an effect on the flow of river systems over time.
Geology Runoff Dams Climate Tectonism
The force behind a river's flow from high to low elevations is
Gravity
RUnoff
Increases flow, causing flooding
Which of the following physical parameters show a decrease from the headwaters to the mouth of a river?
Maximum grain size
vegetation
Plants stabilize stream bank and protect against erosion
Select all the natural causes for flooding from the list below.
Regional precipitation Local heavy precipitation Snowmelt Eruption of snow-covered volcano
Select the three measurements needed to calculate discharge of a river at a certain point.
River depth Velocity of the water River width
The principal processes that sculpt Earth's landscape are erosion and deposition by
Streams
Geology
Streams erode soft rocks more easily than hard rocks
Tectonism
Tectonism Drop zone Can increase the slope and supply of coarse sediments correct Toggle Button Unavailable. Can increase the slope and supply of coarse sediments
What is a drainage basin?
The naturally defined area that a stream drains
Which of the following are ways in which tectonism, such as an uplift of a mountain, can affect drainage?
The uplift can increase precipitation into the drainage. The uplift can increase the slope of the drainage. The uplift can cause a rain shadow on the other side, causing a decrease in the runoff into the drainage. The uplift can increase the supply of coarse sediment.
How can the melting of an ice sheet or glacier affect a river's drainage?
Uplift of the land after the glacier melts can change drainage patterns and direction. Melting of the ice releases tremendous amounts of water and sediment that lead to new or larger channels.
An important and widespread geologic agent in eroding, transporting, and depositing sediment is flowing
Water or H2O
The erosional base level of a river can be ______. Multiple select question.
a closed land basin an ocean a lake
A decrease in the size of sediments carried by a river usually reflects ______ in the gradient of the river.
a decrease
Oceans, lakes, or the bottoms of closed basins are all examples of _________ levels of rivers.
base
A community experiences two floods with stream discharge equal to the 100-year recurrence interval. The floods occur in 1980 and 1990. When will or did the next flood occur?
can occur in any year
A stream ______ erode below its base level.
cannot
Fill in the Blank QuestionYour Answer incorrect The volume of water flowing through a stretch of a river is the ________ and is measured by multiplying the river depth by river width and river velocity.
discharge
Acting as major sculptors of Earth's surface, rivers and streams ________the landscape, carry the materials, and later deposit the sediments.
erode
An event in which the amount of water flowing through a river channel overflows its banks is a(n)
flood
The driving force behind a river's flow is ______.
gravity
The ______ the velocity of a river, the ______ its capacity to carry sediment.
higher; larger
The uplift of high mountain ranges increases slope and precipitation causing a subsequent decreaseBlank 1Blank 1 decrease , Incorrect Unavailable in the amount of sediment available for a stream to transport.
increase
When a river floods and deposits sediment parallel to and along the river channel, a(n) )_________ is formed.
levee
Flooding can be prevented by building_________ parallel to river channels. However, these structures do fail, and construction to prevent the worst possible flooding events is not affordable
levees
Dissolved
matches Choice Chemically soluble ions transported by the river
The discharge of a river is measured in cubic ______ per second.
meters
______ are formed beside low-gradient rivers when floods occur and sediments build up along the channels. These features become barriers to water returning to the river from the floodplain.
natural levees
A stream or river that flows all year is ______.
perennial
A river cannot erode below ______.
sea level
The higher the velocity of a flowing stream, the larger its capacity to carry
sediment
We disrupt the balance of a river system when we discourage the process of migration and meandering by ______ streams.
straightening
The term "100-year flood" signifies ______.
the size of a flood that is predicted to have a 1 in 100 probability of occurring in a given year
Rank the seasons from the lowest discharge of water to the highest for a river located in the Upper Midwest of the U.S. (Place the season with the lowest discharge on top.)
winter, fall, summer, spring
What is happening to coarse-grained sand in a stream velocity of 70 cm/s?
It is being transported as bedload.
What is happening to silt and clay in a stream velocity of 5 cm/s?
It is being transported as suspended load.
As the gradient decreases in a river, the size of the sediment that can be transported
decreased
The amount of water flowing through a channel over a given amount of time is called its ______.
discharge
What is a very common and important geologic agent in eroding, transporting, and depositing large amounts of sediment daily?
flowing water