GY Learnsmart Ch

Below are listed the sinuosity indices of three streams. Rank them by the likely size and number of the bends in them by using their sinuosity index. Assume all three have the same down-valley length. (Put the one with the largest/most bends on top.)

1. 1.7 2. 1.5 3. 1.2

Rank in order from the beginning (at the top) the processes necessary to create entrenched meanders.

1. A meandering river flows across a floodplain. 2. A tectonic event causes an uplift, causing the river to erode downward. 3. Further incision by the river creates more entrenchment.

Rank the following particle sizes transported by water from smallest to largest. (Place smallest particle at the top.)

1. Clay 2. Slit 3. Sand 4. Cobbles 5. Boulders

Rank the formation of terraces by rivers from the first stage at the top to the last stage on the bottom.

1. Deposition of sediment occurs on the floodplain. 2. A drop in the base level of the river results in downcutting through deposits. 3. Further downcutting occurs, and the river abandons the previously formed floodplain. 4. The oldest floodplain becomes isolated as the river downcuts, leaving a terrace.

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.)

1. Winter 2. Fall 3. Summer 4. Spring

What is a drainage divide?

A ridge or strip of high ground separating one drainage basin from another.

What is a point bar?

A sandbar deposited along the inside of a stream meander due to lower velocity

What is a drainage network?

A series of interconnected streams that when combined drains a larger area than any one stream

What is a braided stream?

A stream that flows in a network of many interconnected rivulets around numerous bars

Which of the following statements are true with regard to a stream's formation or cessation (ending)? (Choose all that apply.)

Changing the amount of water or sediment supplied to a basin can cause the formation of a stream or cause its end.; Changing the slope of the land can cause the formation or cessation of a stream.

At a flow velocity of 12 cm/sec, which of the following statements are true? (Identify all that apply.)

Clay is transported as suspended sediment; Most sand sizes are transported as bedload

Match the condition on the left with the effect on the river or drainage system on the right.

Dam: Changes the base level because of sediment buildup Tectonism: Can increase the slope and supply of coarse sediments Runoff: Increases flow, causing flooding Geology: Streams erode soft rocks more easily than hard rocks Vegetation: Plants stabilize stream bank and protect against erosion

Match the type of sediment load to its description.

Dissolved: Chemically-soluble ions transported by the river Suspended: Clay and slit carried indefinitely above the riverbed Bed: Material carried on the bottom of a river by pushing, bouncing, rolling, and sliding; usually sand and gravel

True or false: Geologically speaking, the largest river systems in the world are permanent features on the landscape.

False

Which of the following summaries best describes how flooding by streams impacts humans.

Floods have both negative and positive aspects as they cause destruction and yet also provide floodplains with sediments and nutrients.

___ is the force behind a river's flow from high to low elevations.

Gravity

Match the location of the diagram with a description of the shape of the river.

Left-side diagram: Braided river Middle diagram: River with low sinuosity Right-side diagram: Meandering river

How does rainwater cause erosion on the ground?

Rain causes splash erosion as the drop hits the ground and flows over it, causing sheet erosion.

Select the three measurements needed to calculate discharge of a river at a certain point.

River width; Velocity of the water; River depth

Select two ways that mountain streams obtain their sediments.

Soil and/or sediment slides down into the drainage area; Tributaries bring sediments into the drainage area.

Match the river drainage pattern with the appropriate description of its geology.

Structurally controlled pattern: Drainage occurs on eroded layers or structures and then cuts across a ridge to follow a different weak layer. Radial drainage pattern: Drainage is found don symmetrical mountains such as volcanoes. Dendritic drainage pattern: Treelike pattern develops on rocks with similar resistance to erosion.

Select the two conditions that resulted in the 1993 upper Mississippi River flood.

The ground was already saturated from early spring rains; Severe precipitation was caused by warm moist air from the Gulf of Mexico and cold Arctic air merging

Isostatic rebound can change the slope of the rivers and streams flowing over the land. What is isostatic rebound?

The uplift of land that occurs after the weight of an overlying mass is removed

In what ways do streams impact peoples lives? (Choose all that apply.)

They allow for generation of energy without the release of carbon dioxide; They provide floodplains with nutrients required by plants and crops; They are used as transportation routes

In what ways do streams impact people's lives? (Choose all that apply.)

They provide floodplains with nutrients required by plants and crops; They allow for the generation of energy without the release of carbon dioxide; They are used as transportation routes.

What is the name of the subsidiary channels that join up with the main river channel?

Tributaries

How can the melting of an ice sheet or glacier affect a river's drainage? (Choose all that apply.)

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 leads to new or larger channels

Select the human-caused flooding events from the list of flood causes below. (Choose all that apply.)

Urbanization; Dam failure

___ is a property of fluid that is defined as the resistance to flow.

Viscosity

Select consequences to a river when a dam is constructed. (Choose all that apply.)

Water released from the dam is clear (no sediment) and has a new capacity to erode and transport sediments downstream; The dam causes the river to deposit its sediment load upstream of the dam; The dam creates a temporary base level for the river.

Define the landforms associated with the headwaters of mountain streams.

Waterfall: Occurs when a stream or river's gradient is so steep that water goes over a ledge or cliff Rapid: Occurs along a river and is characterized by turbulent water Lake: Occurs where water is impounded by some obstruction Pool: Occurs when water slows down and piles up upstream of a rapid

Oceans, lakes, or the bottoms of closed basins are all examples of ___ levels of rivers.

base

The lowest level to which a river can erode is its ___.

base level

Streams that cave directly into the rocks that compose a mountain or other area are ___ streams.

bedrock

The process of meander formation begins when a difference in roughness on the ___ causes water to move faster on one side of the channel than on the other.

bottom

A(n) ___ is formed where a river meets the sea, slows down, and deposits its sediments.

delta

The feature formed when a river deposits its sediment near its mouth is a(n) ___.

delta

The direction of stream flow from higher elevations to lower elevations is referred to as the ___ direction.

downstream

Rivers and streams ___ the landscape, carry the materials, and later deposit the sediments, thereby acting as major sculptors of Earth's surface.

erode

On the outside of a meander, the water velocity is faster and causes ___, and on the inside of a meander, the water velocity is slower, which causes ___.

erosion; deposition

When a stream's discharge rapidly rises above and then quickly falls below flood stage, it is known as a ___ flood.

flash

A(n) ___ is an event in which the amount of water flowing through a river channel overflows its banks.

flood

A(n) ___ is a broad strip of land on either side of a stream channel that is covered by water during a flood and replenished by sedimentation.

floodplain

Stream measurements are collected continuously and automatically at a(n) ___ station.

gauging

What is the word used to describe the change in elevation for a given stream or river over a horizontal distance?

gradient

The two primary forces that drive a river system are ___ and ___.

gravity; precipitation

The area of the origin of a river is its ___, and the ___ the end of the river.

headwaters; mouth is

Water moving smoothly in parallel layers is called ___ flow, but water moving in a chaotic nature downstream is called ___ flow.

laminar; turbulent

Meanders, floodplains, and river terraces are commonly found along ___-gradient rivers.

low

The discharge of a river is measured in cubic ___ per second.

meters

What type of lake is created when a cutoff meander becomes isolated? The answer is just one word.

oxbow

A(n) ___ stream or river is one that flows year-round, whereas a(n) ___ stream does not flow the entire year.

perennial

The type of sediment transport that involves a series of leaps or bounces off the bottom of a steamed is ___.

saltation

A delta is formed where a river meets a ocean because ___ is deposited as the river loses speed.

sediment

When is sediment most likely to be deposited? When the ___.

sediment supply exceeds a stream's capacity to transport it

The size of the drainage basin and the ____ the drainage basin influence the flow response to rainfall.

shape of

The amount that a river or steam channel curves in a given length is called its ___.

sinuosity

River ___ are relatively flat benches that are perched above a river or stream and stair-step upward and outward from the active channel.

terraces

How is flood stage defined? Flood stage is reached when ___.

the amount of discharge needed to overtop a stream's banks and spill onto the floodplain is reached