Rivers Flashcards

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1
Q

What are the names of a rivers courses?

A

lower course
middle course
upper course

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2
Q

What is a drainage basin?

A

an area of land where water from rain or snow melt drains downhill into a body of water such as a river

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3
Q

What is a watershed?

A

the area of high land forming the edge of a river basin.

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3
Q

What is a long profile of a river?

A

a way of displaying the channel slope (gradient) of a river along its entire length

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4
Q

3 types of cross profile of river?

A

.V shaped valley (steep sided - narrow shallow)
.floodplain (wider, flat - wide and deep)
.levees (very wide and flat - wide and deep)

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4
Q

Why does gradient of a river change along its long profile?

A

shows a steep upper course as this section is in upland areas made of hard rock
middle and lower course the land becomes flatter because rock around is softer.

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5
Q

What is cross profile of a river?

A

a section taken sideways across the channel or valley

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6
Q

What is channel depth?
downstream change, reason

A

how deep the channel is
↑ river deep due to erosion - more water added by tributaries

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6
Q

What is channel depth?
downstream change and reason

A

how wide channel is
↑ rock erodes away at lower course- rock is softer

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7
Q

What is gradient of a river?
downstream change, reaosn

A

how steep the channel is
↓ land further down is flatter because rock softer as go down

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8
Q

What is load quantity?
downstream change, reason

A

average amount of sediment
↑ faster water can erode more material and carry more material

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8
Q

What are fluvial processes?

A

term given to processes that shape our rivers

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9
Q

What is the velocity of a river?
downstream change, reason

A

speed of the water
↑ friction lower in lower course because river is wider, deeper and smoother

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10
Q

What is load size?
downstream change, reason

A

average size of sediment and point of river
↓ attrition means sediment is eroded into smaller sediment - goes downstream

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10
Q

What is channel bed roughness?
downstream change, reason

A

amount of friction between river bed and water
↓ abrasion means river bed will be eroded to smoother downstream where velocity is higher.

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11
Q

What is discharge of a river?
downstream change, reason

A

volume of water flowing through the river
↑ water added by tributaries, water is travelling faster, rivers are wider and deeper

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12
Q

What is Hydraulic action (river)?

A

power or water eroding river bed and banks

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13
Q

What is abrasion (river)?

A

rocks carried along river wear down bed and banks

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14
Q

What is attrition (river)?

A

rocks being caried by river smash together and break

15
Q

What are interlocking spurs?

A

fingers of land that jut out into the river valley where streams and rivers are forced to flow around in the upper course.

16
Q

How to form a waterfall?

A

river flows down along hard rock
when reaches it erodes soft rock creating a plunge pool formed by hydraulic action and abrasion
cliff becomes unstable falls by gravity
continues until waterfall shape is formed

17
Q

What is solution (river)?

A

chemical erosion caused by dissolving rocks in river water

18
Q

how does a meander develop?

A

.slower flow on inside, faster flow on outside.
.erosion on outside deposition on inside
.outside wears away and a meander is formed.
.more erosion and deposition creates a horse shoe shape, until river cuts straight across.
.eventually not going round bend anymore so it detaches and dry’s out forming an oxbow lake.

19
Q

What is thalweg?

A

line of fasted flow in a river

19
Q

why does thalweg go to outside of meanders?

A

because it cant go quickly round a turn and needs to keeps it momentum by going a slightly longer route.

20
Q

where are floodplain and levees found?

A

middle and lower course

21
Q

What is a floodplain?

A

An area of low-lying land next to a river which is prone to flooding

22
Q

What are levees?

A

naturally raised river banks found on the sides of a river channel that is prone to flooding. They are formed after a flood deposits sediment on the flood plain close to the river

22
Q

natural factors that lead to flooding?

A

.heavy rainfall
.very dry ground
.layers of impermeable rock
.steep sided valley

23
Q

What is a hydrograph?

A

shows two graphs – a bar chart showing rainfall and a line graph showing discharge from before, during, and after the rain storm. A hydrograph shows you the ways in which a river is affected by a storm

24
Q

manmade factors that lead to flooding?

A

.building urban areas
.climate change
.deforestation
.agriculutre

25
Q

What is lag time?

A

The time taken between peak rainfall and peak discharge

26
Q

what is discharge measured in?

A

cumecs
cubic metres per second

27
Q

What is the rising limb?

A

Shown on a hydrograph,
period of time river discharge increases

28
Q

what is the falling limb?

A

A period of time in which the river discharge decreases

29
Q

What is baseflow?

A

A volume of water. it is water from the ground, flowing into the channel over a long time

30
Q

hard engineering for rivers?

A

.dams + reservoirs
.channel straightening
.embankments
.flood relief channels

31
Q

what are dams and reservoirs?
+, -

A

they regulate river flow and reduce the risk of flooding
+ flood prevention, water storage, generate hydro electric power
- expensive, large areas of land required

32
Q

What are embankments?
+, -

A

raising the river bank
+hold more water, cheap
- unnatural, increase flood risk downstream

32
Q

What is channel straightening?
+, -

A

You cut meanders to form a straight channel
+ speeds flow of water, protect vulnerable areas
- unattractive, damage wildlife habitats, increase flood risk further down stream

33
Q

what are flood relief channels?
+, -

A

floodwater flows into the relief channel and is taken either to an area where it can be absorbed, or re-enters the river further down its course.
+remove excess water, create wetlands
- expensive 110 million (12km)

34
Q

Soft engineering types for river?

A

.afforesting
.wetlands + storage areas
. floodplain zoning
.river restoration
.flood warning and prep

35
Q

What is afforesting?
+, -

A

planting trees along river valley
+ absorb water, natural
- loss of grassland

36
Q

What is wetlands and storage areas?
+, -

A

store water
+ efficient for storing water
- still releases water out

37
Q

What is floodplain zoning?
+, -

A

not putting houses and buildings on land with high flood risk
+ less damage is caused
- not always knowing how big flood will be, cant move houses that are already on the land

37
Q

What is river restoration?
+, -

A

reintroduces meanders to rivers and restores physical process
+ natural
- can return to its original way without a lot of maintenance

37
Q

What is flood warning and preparation?
+, -

A

The environmental agency monitors rivers and gives out warnings through newspapers, TV, radio and internet when they are likely to flood so people can prepare.
+ time to protect properties
- cant access warning, flash floods can happen too quickly, land still floods