Chapter 16 - Streams and Flooding

Wave action Discharge Vegetation River and ocean ice Sediment load

From the list below, select the factors that control the deposition of a delta.

greatest amount

In flowing water, the upstream side of an obstruction is subjected to the ______ of abrasion.

Blank 1: dendritic Blank 2: radial

The drainage pattern associated with areas where the rocks have the same resistance to erosion is a (blank) pattern, whereas (blank) drainage patterns are found on symmetrical mountains.

floodplain

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

natural arch; window; fin

A large opening that goes all the way through a narrow panel of rock is called a ______. A smaller, but similar opening is called a ______. These features may form in areas where a narrow panel of rocks, called a ______, has formed due to weathering controlled by joints on both sides.

Blank 1: erode

Acting as major sculptors of Earth's surface, rivers and streams (blank) the landscape, carry the materials, and later deposit the sediments.

Blank 1: flood

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

Blank 1: climate or weather Blank 2: tectonics

Besides sea level and rock type, the other two primary factors that influence a stream or river's profile are (blank) and (blank).

Blank 1: meandering

Braided rivers carry more volume and larger size ranges of sediment types than (blank) rivers

Blank 1: meandering

Braided rivers carry more volume and larger size ranges of sediment types than (blank) rivers.

water or sediment supply at the source slope the river flows across elevation at the base level

Changes in the ______ can begin or end the life of a river.

Blank 1: river, stream, creek, or waterway

Changes in water or sediment supply, change in slope, or changes to base level elevation can begin or end the life of a(n) (blank).

Blank 1: sediments

Construction of dams causes an interruption of river flow. River (blank) are deposited upstream of the dam, shortening the life of the reservoir.

braided

Flat-bottomed valleys between mountains would be good places to look for ______ rivers or streams.

Gentle plains

In which location would a geologist look for a river confined to a single channel?

Blank 1: hurricanes or typhoons

Many historic floods are associated with the large precipitation that accompanies a(n) (blank); a good example is the storm named Mitch in 1998 that brought 78 inches of rain in some places in a few days.

low

Meanders, floodplains, and river terraces are commonly found along (blank)-gradient rivers.

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

terraces

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

silt

The particle size transported by water that is in between clay and sand is (blank).

Alluvial fans

These are formed when a steep drainage enters a broad valley and the sediments and debris are deposited.

bridge

This is a natural (blank)

flow

Viscosity is the resistance to (blank) exhibited by fluids.

Blank 1: oxbow

A cutoff meander may develop into a(n) (blank) lake.

oxbow

A cutoff meander may develop into a(n) (blank) lake.

point bar

A depositional feature that has been built on the inside of a stream channel curve because of lower velocity is a ______.

bedrock

A stream in a mountainous area that is carved from bedrock is called a(n) (blank) stream.

perennial

A stream or river that flows all year is ______.

braided

A stream that flows in a network of many interconnected rivulets around numerous bars is a(n) (blank) stream.

Blank 1: perennial Blank 2: ephemeral or intermittent

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

Blank 1: water or H2O

An important and widespread geologic agent in eroding, transporting, and depositing sediment is flowing (blank).

Blank 1: entrenched or incised

As meanders develop on a floodplain and either the base level drops or a tectonic event causes uplift, the meanders deepen and become (blank).

channels

As water flows, it accumulates in natural cracks, which eventually form ______ rather than spreading across the land.

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

Define the landforms associated with the headwaters of mountain streams.

Yes

Do changes in tectonics, human development, and geology affect river systems?

Blank 1: Mississippi Blank 2: levees

During the 1993 flood on the upper (blank) River, floodwaters flowed onto the floodplain because levees did not hold the water back. It took months for the floodplains to dry out because the (blank) trapped the water, preventing it from flowing back into the river channel.

natural lakes geologic structures lava flows dams

Features that occur along the Colorado River include ______.

Natural arch > a large opening that goes all the way through a narrow panel of rock Fin > A narrow panel of rocks that is the result of weathering controlled by joints on both sides Window > A small opening that goes all the way through a narrow panel of rock

Match the feature with its description.

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 on symmetrical mountains such as volcanoes Dendritic drainage pattern > Treelike pattern develops on rocks with similar resistance to erosion

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

Blank 1: scars Blank 2: oxbow

Meandering rivers leave behind exposed curved ridges called meander (blank) marked by lines of vegetation or as curved dry depressions. When the depressions are filled with water, they are (blank) lakes.

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

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

Blank 1: gravity

Rivers are dynamic systems driven by precipitation and (blank). (Hint: the answer is just one word.)

channel

Rivers on gentle plains usually occupy a single ______ rather than being braided.

Eruption of snow-covered volcano Local heavy precipitation Snowmelt Regional precipitation

Select all the natural causes for flooding from the list below.

Single channels River terraces Floodplains Meanders

Select common features located along low-gradient rivers.

Tectonism Dams Climate Runoff Geology

Select conditions that have an effect on the flow of river systems over time.

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

Select consequences to a river when a dam is constructed.

Chemical makeup of sediment

Select the answer that is not a factor in the deposition of deltas.

Unusually severe thunderstorm Narrow canyon Steep slopes of the river canyon

Select the conditions that caused the 1976 Big Thompson River flood near Estes Park, Colorado.

Dam failure Urbanization

Select the human-caused flooding events from the list of flood causes below.

Depth Width Velocity

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

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

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

the amount that a river or stream channel curves in a given length

Sinuosity refers to ______.

tributaries

Smaller subsidiary channels that feed the main channels of rivers are ______.

Colorado

Steep slopes in a(n) narrow canyon plus an unusually large thunderstorm resulted in the 1976 Big Thompson River flood near Estes Park in the state of (blank), just outside of Rocky Mountain National Park.

precipitation and gravity

Streams are systems driven by ______.

higher; larger Reason: A river can have a larger capacity at faster flow velocities because it can transport larger particles, erode more material, and thus add to the total amount of sediment being transported (the stream's capacity).

The ______ the velocity of a river, the ______ its capacity to carry sediment.

probability

The ability to determine the ______ of a flooding event is based on river flow data. The more data collected and the greater the time span for data collection, the better understanding we have of the chance of future flooding events.

discharge

The amount of water flowing through a channel over a given amount of time is called its ______.

headwaters; mouth is

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

basin

The area that a stream naturally drains is called a drainage (blank).

Blank 1: lowest or minimum

The base level of a river is the (blank) elevation to which the river can erode.

meters

The discharge of a river is measured in cubic (blank) per second.

delta

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

Blank 1: terraces

The flat benches that are perched above a river or stream and that stair-step upward and outward from the active channel are (blank).

Blank 1: elevation, height, or vertical distance

The gradient of a stream or river is defined as the change in (blank) for a given horizontal distance.

Blank 1: sediment

The higher the velocity of a flowing stream, the larger its capacity to carry (blank).

base level

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

higher

The more years of river flow data that are collected, the ______ the probability of predicting a major flooding event.

Blank 1: headwaters or head Blank 2: mouth

The origin of a river is called its (blank), and the end of a river is called its (blank).

Blank 1: rivers or streams

The principal processes that sculpt Earth's landscape are (blank).

bottom

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.

viscosity

The property of a fluid that is defined as the resistance to flow is (blank).

more varied

The size of sediments in braided rivers typically is ______ than that carried by meandering rivers.

discharge

The volume of water flowing through a stretch of a river is the (blank) and is measured by multiplying the river depth by river width and river velocity.

the headwaters of mountain streams

Waterfalls, lakes, and large boulders are landforms that characterize ______.

A mountainous stream flowing through a carved bedrock channel

What is a bedrock stream?

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

What is a braided stream?

The naturally defined area that a stream drains

What is a drainage basin?

Water overflows a stream's channel.

What is a flood?

A broad strip of land built up by sedimentation on either side of a stream channel and covered with water during a flood

What is a floodplain?

An arch-shaped features that span a (former) stream

What is a natural bridge?

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

What is a point bar?

Flowing water

What is a very common and important geologic agent in eroding, transporting, and depositing large amounts of sediment daily?

The process of grains chipping, scraping, and sandblasting the streambed as they move downstream

What is stream abrasion?

Blank 1: Tributaries

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

gradient

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

Clay Sand Silt

What types of sediments or rocks are deposited by low-relief streams?

Low-relief streams

What types of streams typically deposit clay- to sand-sized sediments?

oxbow lakes

When meander scars are filled with water, they are ______.

Blank 1: alluvial Blank 2: fans

When steep, narrow drainages enter broader, more gentle valleys and streams deposit the large sediments they are carrying, (blank) form.

turbulent; rapids

When the gradient of a stream steepens or the channel is constricted by bedrock or obstacles, the flow of water becomes ______ forming ______.

rapids

When water flows chaotically through narrow channels or over large rocks and other debris that partially block the channel, (blank) are formed.

Colorado

Which large river runs from the high Rocky Mountains to western Mexico passing lakes, dams, reservoirs, geologic structures, incised meanders, and finally a delta on its journey? The (blank) River.

Prolonged drought followed by intense precipitation Stalled hurricane Failure of a dam Rainfall coinciding with snowmelt and ice dams in a river

Which of the following are considered to be causes for severe flooding events other than precipitation alone?

Climate Sea level Tectonics Rock type

Which of the following are primary factors that influence a stream's profile?

Flat-bottomed valleys between mountains Broad, sloping plains that flank mountain ranges

Which of the following locations would be the two most common areas in which to find a braided stream or river?

Maximum grain size

Which of the following physical parameters show a decrease from the headwaters to the mouth of a river?

Channel size Sediment load Discharge

Which of the following physical parameters show an increase from the headwaters to the mouth of a river?

channels

______ are formed as flowing water collects in natural cracks or low spots. Once formed, these capture additional runoff within the drainage basin.

Deltas

______ are formed as rivers slow down when they reach their mouth and empty into an ocean.