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