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Geography > Rivers > Flashcards

Rivers Flashcards

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1
Q

What is a drainage basin

A

Drainage basin also know as river basin or river attachment area = the area of land drained by a river and is tributaries(streams)

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2
Q

What is a river mouth

A

where a river meets the sea or lake

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3
Q

What is watershed

A

the edge/ boundary of a river/drainage basin

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4
Q

What is a tributary

A

Freshwater streams that branch of the main body of water (mainstream)

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5
Q

What is a confulence

A

The point where two or more rivers meet

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6
Q

What is discharge

A

The volume of water passing a point or location along the river channel in a given time. Measured in cubic metres per second

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7
Q

What is a source

A

An area in which a river begins

The starting point of a river, often a spring, melting glacier , lake or wetland

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8
Q

What is an esturary

A

a coastle body of water where tide meets fresh water

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9
Q

What is a meander

A

A bend in a river the occurs due to erosion

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10
Q

What is weathering

A

the breakdown of rocks

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11
Q

What is erosion

A

the removal of weathered material from the land by water, ice or wind

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12
Q

What is bedload

A

Fragments of rock which have come into contact with the bed of the river channel during their transportation

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13
Q

What is a floodplain

A

An area of low lying ground next to a river that is affected by flooding if the rover overflows it’s banks

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14
Q

What is a delta

A

a landform which develops when a river meets a slow body of moving water such as a lake or the sea. Sediment builds up above the water level, forcing the river to split into distributaries and forming a delta.

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15
Q

What is slip-off

A

a gentle slope on the inside of a meander, it is formed where the river flows more slowly and with less energy so sediment is deposited on the inside of the meander

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16
Q

What is a levee

A

a raised bank of sediment along the sides of a river channel

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17
Q

What is a gradient

A

how steep a slope , river channel or valley is

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18
Q

What are some of the opportunities the river provides us with

A

Fishing
Jobs
Tourism
White water rapids
Ecosystems
Transportation
Dams
Agriculture
Clean water supply

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19
Q

What are the 4 types of movement/transportation in rivers

A

Traction
Saltation
Suspension
Soloution

20
Q

What is traction

A

The heaviest materials are dragged along the bottom of the river.

21
Q

What is saltation

A

Slightly heavy materials Leapfrogging - ( being pulled up by the river but falls down due to weight )

22
Q

What is suspension

A

Light materials picked up by the river and float downstream

23
Q

What is solution

A

Dissolved materials that arnt visible float along downstream

24
Q

What are the four processes of river erosion

A

Hydraulic Action
Abrasion
Solution (sometimes called corrosion)
Attrition

25
Q

What is hydraulic action

A

force of a water against a river bed and bank, trapping air in the cracks and forcing them to split apart

26
Q

What is Abrasion

A

rocks and pebbles, gravel, sand rolls and collides with the channel bed and banks, this wears down the rocks and pebbles like sandpaper

27
Q

What is Solution

A

Solution (sometimes called corrosion):
some minerals (mainly the carbonate minerals found in rocks such as limestone and chalk) are dissolved by the weak acids found
in the riverwater

28
Q

What is Attrition

A

Rocks and pebbles floating along the river channel hit eachother wearing eachother down.

29
Q

What are the processes of deposition

A

When a river loses its energy it drops any material it has been carrying.

Factors leading to deposition:
- shallow water
- at the end of the river’s journey, at the river’s mouth
- when the volume of water decreases

The heavier material is deposited first and as the river continues to slow down and become shallower the smaller material is deposited.

30
Q

What are some of the characteristics of the upper course of a river

A

Narrow and steep sided
Where the source is located
lots of waterfalls and v-shaped valleys
Hilly and muddy ground
Large sediment

31
Q

What are some of the characteristics of the middle course of a river

A

Flat land
Agricultural land
Meanders

32
Q

What are some of the characteristics of the lower course of a river

A

River is wide
River is deep
where mouth is located
Lots of flat Land
Agricultural land
Mix of salt and fresh water

33
Q

What is a delta and how is it formed ( 4 marks )

A

A delta is formed when a river reaches a lake or the sea, the water will slow down and loose the power to carry sediment, this sediment is dropped at the mouth of a river. some rivers drop so much sediment that waves and tides can’t carry it all away, this builds up in layers forming a delta.

34
Q

How is a water fall formed ( 4 to 6 marks )

A

Waterfalls are formed when there is an area of hard rock overlaying an area of soft rock. the wwater passes over this area and the soft rock erodes at a faster pace then the hard rock, this gradually forms a step in the riverbed. As erosion continues an overhang is created as there is no more soft rock under the hard rock. Abrasion and hydraulic action continue to erode more rock which will creat a plung pool. Over time the overhang increases in size and the hard rock above collapses. Extra - this proccess happens multiple times and the waterfall retreats upstream, a steap sided valley is left where the waterfall once was (this is called a gorge).

35
Q

What and how is a v-shaped valley formed ( 4 - 6 marks )

A

V-shaped valleys are geological locations creat by erosion over long periods of time. they are located in the upper course of the river. the reason why they appear as a v-shape is due to the verticle/downward erosion being stronger then the lateral/horisontal erosion. Water will flow down a v-shape valley quick because it has a lotof energy. the main type of erosion here is abbraision- check this

36
Q

How is a Meander formed ( 4 marks )

A

Meanders form where there is a small bend in the river. wayer will flow quicker on the outer bend and slower on the inner bend. this means erosion and will be more frequent on the outer bend making it wider. This forms a river cliff. Deposition will also occur on the inner bend creating a slip off slope.

37
Q

What is an oxbow lake and how is it formed ( 4 marks )

A

An oxbow lake is the result of the neck in a meander being fully eroded. Water will now flow the quickest way possible (through the eroded neck) and the meander will slowly dry up. Deposition will also occur at the start and end of the meander seperating it from the river creating an oxbow lake. the types of erosion that have occured to erode the river neck are abrasion and hydraulic action

38
Q

What is a flood

A

A flood is an overflow of water onto normally dry land.

39
Q

What are factors that cause flooding

A

-overflowing of river
-Urbanization
-Land already saturated due to previous rainfall
-Heavy rainfall
-storm surges
-tsunamies
-geographic position (the confluence of two rivers)

40
Q

What is the Bradshaw model?

A

ADD HERE

41
Q

Looking at the Bradhaw model describe how factors change as the river moves down stream

A

Discharge - amount of water at a given point in a river. As the river goes downstream the discharge increases as tributaries add more water

Channel Width- distance across channel increases due to discharge

Channel Depth - height form water surface to the channel bed increased downstream due to increase in discharge of the river

Velocity - the speed of the water flows measured in meters per second. Stead increase downstream

Load quantity. how much material eh river is carrying and increases with discharge and velocity

Partial size - size of Peebles in the bed of the river, decreased downstream due to erosion - attrition

Channel bed roughness - decreases due to fewer stones and smaller particle size

Slope angle - measure in degrees - decreases as you move downstream

42
Q

How are rapids formed

A

Rapids are areas of rough water, often called white water. They are normally found in the upper course of a river and are formed when you get alternate layers of hard and soft rock. The soft rock erodes quicker creating an uneven river bed and turbulent water.

43
Q

What are interlocking spurs

A

In the upper course there is more vertical erosion. The river cuts down into the valley. If there are areas of hard rock which are harder to erode, the river will bend around it. This creates interlocking spurs of land which link together

44
Q

What are levees and how to they are occur

A

Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs.

Sediment that has been eroded further upstream is transported downstream.
When the river floods, the sediment spreads out across the floodplain.

When a flood occurs, the river loses energy. The largest material is deposited first on the sides of the river banks and smaller material further away.

After many floods, the sediment builds up to increase the height of the river banks, meaning that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future.

45
Q

What is the Three Gorges Dam and four advantages and disadvantages of it?

A

Dam built in 2003 on Yangtze River (China)

Advantages:
-protects 10 million people from flooding
-produces hydroelectric energy (22500 megawatts)
-allows boats to use it (transportation of goods)
-lowers Chinas dependency on coal

Disadvantages
-over 200,000 people relocated
-cost 25 billion usd to build
-interferes with aquatic life
-main area of flooding is further down the river (not as efficient as possible)

46
Q

What is the Kissimmee River and four advantages and disadvantages of it?

A

Channelised River in Florida USA, took place in between 1962 and 1972. The channelisation had an unexpected impact of endangering some of the wildlife, so they restored

Benefits of restoration
-helps rebuild ecosystem
-benefits the reservation of of avian species
increased job opportunities

Disadvantages of restoration
-expensive, cost 980 million USD
-time consuming, restoring it took 16 years
-since the river is more still it can lead to more evaporation which will mean more water loss

Geography (12 decks)

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