Rivers

Question 1

What are the names of a rivers courses?

Answer 1

lower course
middle course
upper course

Question 2

What is a drainage basin?

Answer 2

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

Question 3

What is a watershed?

Answer 3

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

Question 3

What is a long profile of a river?

Answer 3

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

Question 4

3 types of cross profile of river?

Answer 4

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

Question 4

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

Answer 4

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.

Question 5

What is cross profile of a river?

Answer 5

a section taken sideways across the channel or valley

Question 6

What is channel depth?
downstream change, reason

Answer 6

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

Question 6

What is channel depth?
downstream change and reason

Answer 6

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

Question 7

What is gradient of a river?
downstream change, reaosn

Answer 7

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

Question 8

What is load quantity?
downstream change, reason

Answer 8

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

Question 8

What are fluvial processes?

Answer 8

term given to processes that shape our rivers

Question 9

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

Answer 9

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

Question 10

What is load size?
downstream change, reason

Answer 10

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

Question 10

What is channel bed roughness?
downstream change, reason

Answer 10

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

Question 11

What is discharge of a river?
downstream change, reason

Answer 11

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

Question 12

What is Hydraulic action (river)?

Answer 12

power or water eroding river bed and banks

Question 13

What is abrasion (river)?

Answer 13

rocks carried along river wear down bed and banks

Question 14

What is attrition (river)?

Answer 14

rocks being caried by river smash together and break

Question 15

What are interlocking spurs?

Answer 15

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

Question 16

How to form a waterfall?

Answer 16

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

Question 17

What is solution (river)?

Answer 17

chemical erosion caused by dissolving rocks in river water

Question 18

how does a meander develop?

Answer 18

.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.

Question 19

What is thalweg?

Answer 19

line of fasted flow in a river

Question 19

why does thalweg go to outside of meanders?

Answer 19

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

Question 20

where are floodplain and levees found?

Answer 20

middle and lower course

Question 21

What is a floodplain?

Answer 21

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

Question 22

What are levees?

Answer 22

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

Question 22

natural factors that lead to flooding?

Answer 22

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

Question 23

What is a hydrograph?

Answer 23

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

Question 24

manmade factors that lead to flooding?

Answer 24

.building urban areas .climate change .deforestation .agriculutre

Question 25

What is lag time?

Answer 25

The time taken between peak rainfall and peak discharge

Question 26

what is discharge measured in?

Answer 26

cumecs cubic metres per second

Question 27

What is the rising limb?

Answer 27

Shown on a hydrograph, period of time river discharge increases

Question 28

what is the falling limb?

Answer 28

A period of time in which the river discharge decreases

Question 29

What is baseflow?

Answer 29

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

Question 30

hard engineering for rivers?

Answer 30

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

Question 31

what are dams and reservoirs? +, -

Answer 31

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

Question 32

What are embankments? +, -

Answer 32

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

Question 32

What is channel straightening? +, -

Answer 32

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

Question 33

what are flood relief channels? +, -

Answer 33

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)

Question 34

Soft engineering types for river?

Answer 34

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

Question 35

What is afforesting? +, -

Answer 35

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

Question 36

What is wetlands and storage areas? +, -

Answer 36

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

Question 37

What is floodplain zoning? +, -

Answer 37

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

Question 37

What is river restoration? +, -

Answer 37

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

Question 37

What is flood warning and preparation? +, -

Answer 37

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