GY 102 Topic 8 LS (Ch 13)
perennial intermittent
A (n) _______stream or river is one that flows year round wheras a(n) ____________stream does not flow the entire year.
sediment
A delta is formed where a river meets the ocean because ________ is deposited as the river loses speed.
Point bar
A depositional feature that has been built on the inside of a curve because of lower velocity is a _________.
floodplain
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.
hydrograph
A(n) _________is a type of graph used to display the change in a river's discharge over time.
A meander is cut off from a stream
An oxbow lake is an isolated, curved lake formed when _____
isostatic rebound
As ice sheets melt on land, they allow for the depressed land to rise back up in a process known as
increases eddies
As the velocity of water __________so does the turbulence. this results in the formation of swirls in the current called ________
channels
As water flows, it accumulates in natural cracks, which eventually form _________rather than spreading across the land.
increase
As water velocity in a stream increases, turbulence increases, resulting in a(n) _______ in the water's ability to erode and transport sediment within a channel.
Smaller Sand grains are transported as suspended sediment, and larger grains are transported as bedload
At a flow velocity of 100 c/m/sec which of the following statements is true regarding sand-sized sediment?
Smaller sandgrains are transported as suspended sediment and larger grains are transported as bedload
At a flow velocity of 100/cm sec which of the following statements is true regarding sand sized sediment?
Clay is transported as suspended sediment Most sand sizes are transported as bedload
At a flow velocity of 12cm/sec, which of the following statements are true?
1.7 1.5 1.2
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 most bends on top)
meandering
Braided rivers carry more volume and larger size rangers of sediment types than ________rivers.
waterfalls: 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
Define the landforms associated with the headwaters of mountain streams.
soluble
Dissolution is the process by which __________ materials are removed and transported by flowing water.
streams
Erosion and deposition by __________are the principal processes that sculpt Earth's landscape.
streams
Erosion and deposition by ________are the principal processes that sculpt Earth's landscape.
sediment load wave action discharge vegetation river and ocean ice
Factors that control the deposition of a delta
levees
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.
Variable flow steep graident abundant sediments
From the list below, select the characteristics of a braided river or stream
amount and type of sediment
Geologists use large water tanks in laboratories to study braided river dynamics. They control the slope, the ______, and the consistency of water flow to study how the variables affect the stream system.
Melting of ice releases tremendous amounts of water and sediment that lead to new or larger channels. Uplift of the land after the glacier melts can change drainage patterns and direction.
How can the melting of an ice sheet or glacier affect a river's drainage?
streams deposit more sediment than they erode and by doing so increase the stream's gradient
How does stream aggradation occur?
the amount of discharge needed to overtop a stream's banks and spill onto the floodplain is reached
How is flood stage defined? Flood stage is reached when __________.
A change in the elevation of its base level occurs The slopes across which a stream flows change The source of water or sediment supply changes
Identify the factors that can begin or end a stream's existance
Soil will erode more easily into the streams as less vegetation is present to hold it in place. Rates of downcutting will decrease as the streams have less erosional power resulting from a reduced discharge.
If a drainage network is subjected to drier climatic conditions, which of the following will likely be true?
cutbank point bar
In a meandering river, the deeper outside bend is eroded into the __________ and on the shallower opposite side of this is a (n) _________bar.
Dam: changes the baselevel 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 condition on the left with the effect on the river or drainage system on the right
dam: changes the base level b/c 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 project against erosion
Match the condition on the left with the effect on the river or drainage system on the right.
left-side diagram - braided river middle diagram - river with low sinuosity (slight curve) right-side diagram - meandering river (multiple curves)
Match the location of the diagram with a description of the shape of the river.
Structurally controlled pattern: Drainage occurs on eroded layers or structures and then cuts across a ridge to follow a different weaker layer Radial Drainage pattern: drainage found on symmetrical mountains such as volcanoes Dendric drainage patter: tree like pattern develops on rocks with similar resistance to erosion.
Match the river drainage pattern with the appropriate description of its geology
dissolved: chemically soluable ions transported by the river Supsended: clay and silt carried indefinitely above the riverbed Bed: material carried on the bottom of a river by pushing, bouncing, rolling, and sliding. usually sand and gravel.
Match the sediment type to its description
scars; oxbox
Meander _____ are left behind by meandering rivers as exposed curved ridges, lines of vegetation, or as curved, dry depressions. When the depressions are filled with water, they are ______ lakes.
faster; slower
Meanders cause differences in water velocity in the river channel. On the outside of a meander, water velocity is ______and causes erosion, while on the inside of a meander, water velocity is ______and deposition of sediment occurs.
Horizontal beds deposited partly on land cross-bedded sediments marine clays
Order the sequence of layers produced as a delta builds out into the oceans from flowing rivers, as you would see them in a cross section.
depressions
Potholes or bowl shaped pits are formed when flowing water and sediments swirl in small ______ in the rock.
rapids pools
Rafters enjoying a mountain river trip encounter both turbulent _________and calm ________located upstream of the turbulent areas.
splash
Rainwater creates______ erosion as it hits the ground.
A meandering river flows across the floodplain A tectonic event causes an uplift, causing the river to erode downward Further incision by the river creates more entrenchment
Rank in order from the beginning (at the top) the processes necessary to create entrenched meanders
The drainage network with the fewest number of tributaries A drainage network with an intermediate number of tributaries The drainage network with the largest number of tributaries
Rank the following drainage networks by how quickly they will respond (when peak flow occurs) to an identical rainfall event. (place the fastest reaction at the top)
clay silt sand cobbles boulders
Rank the following particle sizes transported by water from smallest to largest
clay silt sand cobbles boulders
Rank the following particle sizes transported by water from smallest to largest
Deposition of sediment occurs on the floodplain A drop in base level of the river results in downcutting through deposits Further downcutting occurs and the river abandons the previously formed floodplain The oldest floodplain becomes isolated as the river downcuts, leaving a terrace.
Rank the formation of terraces by rivers from the first stage at the top to the last stage on the bottom
winter fall summer spring
Rank the seasons from the lowest discharge of water to the highest discharge for a river located in the upper midwest of the US (season with lowest discharge on top)
terraces
River __________ are relatively flat benches that are perched above a river or stream and that stair-step upward and outward from the active channel.
erode
Rivers and streams __________ the landscape, carry the materials, and later deposit the sediments, thereby acting as major sculptors of earth's surface.
Regional precipitation, local heavy precipitation, snowmelt, eruption of snow-covered volcano
Select all the natural causes for flooding from the list below.
River terraces flood plains meanders single channels
Select common features located along low-gradient rivers.
Tectonism Runoff Climate Dams Geology
Select conditions that have an effect on the flow of a river system over time.
The dam causes the river to desposit 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
Narrow Canyon Steep slopes unusually severe thunderstorm
Select the conditions that caused the 1976 Big Thompson River Flood near Estese Park Colorado
river depth, river width, velocity of the water
Select the three measurements needed to calculate discharge of a river at a certain river.
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
Soil and/or sediment slides down into the drainage area Tributaries bring sediments into the drainage area
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.
Select two ways that mountain streams obtain their sediments
tributaries
Smaller subsidiary channels that feed the main channels of rivers are _________.
Yazoo
Some low gradient rivers have a separate channel that runs parallel to the main channel without rejoining it for many KM this separate channel is a ________stream.
gauging
Stream measurements are collected continuously and automatically at a(n) _______station.
drainage network
Streams often combine their flows and in doing so remove water from a larger area than any one stream does. This interconnected system of streams forms a(n) _______
bedrock
Streams that carve directly into the rocks that compose a mountain or other area are ____streams.
profile
The ______, or gradient of a stream is steeper near the headwaters than at the mouth.
flood
The amount of discharge needed to overtop a stream's banks and spill onto the surrounding land is the _________stage.
discharge
The amount of water flowing through a channel over a given amount of time is called its
sinuosity
The amount that a river or stream channel curves in a given length is called its sinuosity
headwaters, mouth is
The area of origin of a river is its ______ and the _________the end of the river.
an ocean a lake a closed land basin
The erosional base level of a river can be ______.
sediment
The higher the velocity of a flowing stream, the larger its capacity to carry ___________.
for a long
The largest rivers last __________ as features on the landscape.
baselevel
The lowest level to which a river can erode is its
saltation
The movement of sand grains by a series of short leaps or bounces along a stream bed is
Gravity Precipitation
The two primary forces that drive a river system are ______and______.
saltation
The type of sediment transport that involves a series of leaps or bounces off the bottom of a streambed is
Multiplying the velocity by the cross-sectional area of the river
The volume of water flowing through any part of a river per unit of time (discharge) is calculated by
One structure before cutting across a ridge and following a different structure and an annular pattern follows curved layers around a central area.
Trelis and annular drainage patterns are similar in that they are both structurally controlled. How do they differ? A trelis pattern follows _________
FALSE
True or False: Geologically speaking, the largest river systems in the world are permanent features on the landscape
Lake Powell Lake Mead
Two large resevoirs created by damning the colorado river
laminar turbulent
Water moving smoothly in parallel layers is called _________ flow, but water moving in a chaotic nature downstream is called _________ flow.
the direction of flow in which the water is moving
What does downstream mean?
Its location determines if surface water will flow toward the pacific ocean or the gulf of mexico
What does the continental divide indicate?
A stream that flows in a network of many interconnected rivulets around numerous bars
What is a braided stream?
A stream that flows in a network of many interconnected rivulets around numerous bars.
What is a braided stream?
A ridge or strip of high ground separating one drainage basin from another.
What is a drainage divide?
Water overflows a stream's channel
What is a flood?
Large grains collide with other grains in a stream and break them into smaller pieces.
What is stream abrasion?
It is a line of rapid elevation change from the resistant rocks of the Piedmont to the softer sediments of the coastal plain
What is the fall line of the eastern united states?
The location where an abrupt change in gradient occurs
What is the nickpoint of a stream?
distributaries
What is the term for small shifting channels that carry water away from the main river channel and distribute it over the surface of the delta?
gradient
What is the word used to describe the change in elevation for a given stream or river over a horizontal distance?
size shape slope
What three factors of a drainage basin influence the flow response to rainfall?
graded
When a stream is in a steady state in which the balance between the supply of sediment and the amount of sediment that the river can carry is in a near equilibrium, the river is referred to as a ____________stream.
flash
When a stream's discharge rapidly rises above and then quickly falls below flood stage, it is known as a _________flood.
Sediment supply exceeds the streams capacity to transport it
When is sediment most likely to be deposited? When the _____.
deposits
When the amount of sediment exceeds the ability of the current to carry it, the stream _______ the sediment.
At the mouth of a river that empties into the ocean
Where do deltas form?
Tectonics rock type sea level climate
Which of the following are primary factors that influence a stream's profile?
The uplift can increase the supply of coarse sediment The uplift can cause a rainshadow on the other side, causing a decrease in the runoff into the drainage The uplift can increase the slope of the drainage the uplift can increase precipitation into the drainage
Which of the following are ways in which tectonism such as an uplift of a mountain, can affect drainage?
They have turbulent flow They have steep gradients They have the ability to carry large boulders
Which of the following describe the headwaters of moutains streams?
as velocity increases, so does the rivers capacity to carry a larger load
Which of the following is the correct relationship between river velocity and sediment load.
Broad sloping plains that flank mountain ranges flat bottom valleys between mountains
Which of the following locations would be the two most common areas in which to find a braided stream or river?
Sediment load velocity channel size discharge
Which of the following physical parameters increase from the headwaters to the mouth of a river?
Floods have both negative and positive aspects as they cause destruction and yet also provide floodplains with sediments and nutrients
Which of the following summaries best describes how flooding by streams impacts humans?
The type of precipitation can vary during the year The amount of precipitation can vary by season Influx from groundwater can vary during the course of a year
Why does discharge of a stream change during the course of a year?
downcutting
______ occurs as a stream erodes and cuts into the bedrock over which it flows.
gravity
_______ is the force behind a river's flow from high to low elevations.
alluvial fans
________ form when steep, narrow drainages enter border, more gentle valleys and streams deposit the large sediments they are carrying.
deltas
_________are formed as rivers slow down when they reach their mouth and empty into the ocean
Viscosity
________is a property of fluid that is defined as the resistance to flow.
water velocity decreases
deposition in bedrock channels occurs along riverbanks and behind obstacles as _______.
an erosional surface cut into bedrock stream-derived sediment composing former floodplains
stream terraces are composed of either ______ or ________. (Choose the two that apply)
tributaries; a first order system has no tributaries and can flow into a second order stream
what is the stream ordering system? streams are numbered by the _________
velocity sediment load discharge channel size
which of the following paramaters increase from the headwaters to the mouth of a river