River Land Forms- The River Valley

Question 1

what is the course

Answer 1

the path of a river as it flows downhill

Question 2

features found in the upper course of a river

Answer 2

steep gradient
v shape valley
shallow chanell
fast flowing water
erosional processes
waterfalls
gorges

Question 3

features found in the middle course of a river

Answer 3

medium gradient
gently sloing valley
meanders
ox-bow lakes
levees
deeper channel

Question 4

features found in the lowe course of a river

Answer 4

gentle gradient
very wide channel
deep channel
estuaries
mouth of the river

Question 6

vertical erosion

Answer 6

erosion that deepens the river valley and channel causing V-shaped valleys.
found in the upper course of a river.
high turbulence of the water causes the rough angular particles to be scraped along river bed,

Question 7

lateral erosion

Answer 7

widens the river valley and channel during formation of meanders.
usually in middle and lower courses of the river

Question 8

hydraulic action

Answer 8

the force of the river water colliding with rocks breaks rock particles away from the river channel

Question 9

abrasion

Answer 9

eroded rocks picked up the river scrape and rub against the channel wearing it away.
most erosion happens by abrasion

Question 10

attrition

Answer 10

eroded rocks picked up by river crash into each other and break into smaller pieces
causes particle size to decrease from source to mouth

Question 11

solution

Answer 11

river water dissolves some type of rock (chalk and limestone)

Question 12

traction

Answer 12

large particles are pushed along the river bed by water force

Question 13

saltation

Answer 13

pebble sized particles are bounced along the river bed by force of water

Question 14

suspension

Answer 14

small particles (silt, clay) a carried by the water

Question 15

solution

Answer 15

soluble materials (limestone) dissolve and are carried by the water

Question 16

deposition

Answer 16

.a river drops eroded material
.occurs when river loses velocity and energy
dominant in lower course

Question 17

why do rivers slow down and deposit material

Answer 17

.volume of water falls
. the amount of eroded material increases
. the water is shallower
the river reaches mouth

Question 18

how are waterfalls formed

Answer 18

1.)when a river flows over an area of hard rock
2.) the softer rock is eroded(hydraulic action and abrasion) forming a step in river
3.) over time, a steep drop is created (waterfall)
4.) hard rock undercut by erosional processes- collapses
5.)

Question 19

how is a plunge pool created

Answer 19

hard collapsed rocks undercut the soft rock at the bottom of the waterfall, via vertical abrasion

Question 20

how is a gorge formed

Answer 20

over time more undercutting leads to waterfall being pushed back, causing behind a steep gorge

Question 21

what a meanders

Answer 21

large bends in a river
found in the middle and lower courses in a river formed by erosion and deposition

Question 22

how are meanders formed

Answer 22

1.)current is faster on the outside of the bend (river channel is deeper)
2.) more erosion takes place on the outside of a bend- forming river cliffs
3.) current is slower on the inside bend of a river, because river channel is slower
4.) more material is deposited on the inside of the bend, forming slip of slopes

Question 23

how are ox-bow lakes formed

Answer 23

1.)erosion over times causes the inside bends to get closer until only a small bit of land between rock (neck)
2.) river breaks through this land and flows through the shortest course
3.) deposition over time cuts of meander, forming an ox-bow lake

Question 24

flood plain

Answer 24

wide valley floor on each side of the river that flood
found in middle and lower courses of river

Question 25

how do flood plains build up

Answer 25

when rivers flood, water slows down losing energy and deposits material on each side of the river- building up the flood plain deposition that happens on the slip of slope of meanders build up the flood plain

Question 26

levees

Answer 26

natural embankments along the edges of a river channel

Question 27

how to levees build up

Answer 27

during a flood, eroded material is deposited over whole flood plain over time deposited material builds up, creating levees along the edges of the channel

Question 28

esturies

Answer 28

tidal areas where the river meets the sea found in the lower course of a river estuary water is tidal- water level rises and falls each day

Question 29

river discharge

Answer 29

the volume of water flowing in a river per second

Question 30

what is river discharge measured in

Answer 30

cumecs (cubic metres per second

Question 31

hydrographs

Answer 31

show how the discharge at a certain point in a river changes in relation to rainfall

Question 32

1.) peak discharge

Answer 32

the highest discharge in the period of time that is being recorded

Question 33

2.) lag time

Answer 33

the delay between peak rainfall and peak discharge

Question 34

3.)rising limb-

Answer 34

the increase in river discharge as the river returns to normal level

Question 35

4.)falling limb-

Answer 35

the decrease in river discharge as the river returns to normal level

Question 36

how is lag time affected by physical and human factors

Answer 36

lag time occurs because most rainfall doesnt land in a river channel either flows as surface runoff or soaks into the ground (infriltration)

Question 37

Heavy rainfall

Answer 37

Heavy rainfall means that water arrives too quickly to infriltrate, so there is more surface runoff- increases discharge

Question 38

geology

Answer 38

clay soils and some rocks (granite) are impermeable(don't allow infiltration) so runoff is increased

Question 39

prolonged rainfall

Answer 39

prolonged rainfall can saturate the soil. Any further rainfall cannot infiltrate, increasing runoff in river channels

Question 40

relief (changes in land heights)

Answer 40

if a river is in a steep sided valley, water will reach river channel quicker increases discharge

Question 42

Hard engineering

Answer 42

.Man made structures built to control water the flow of rivers and reduce flooding This can reduce the risk of flooding

Question 43

What Dams and reservoirs

Answer 43

Barriers built across rivers Found in the upper course Reservoirs are artificial lakes formed behind a dam

Question 44

Benefits of dams and resovoirs

Answer 44

Reservoirs store water after heavy rain, control water flow and prevent flood’s downstream Generate hydroelectric power

Question 45

Disadvantages of dams and reservoirs

Answer 45

Dams are very expensive to build. Reservoirs can flood existing settlements Material is deposited in the reservoir,. So farmland downstream can become less fertile.

Question 46

What is channel straightening

Answer 46

Meanders are removed by building artificial straighter channels

Question 47

Benefits of channel straightening

Answer 47

Water leaves the area more quickly so flood risk is lower

Question 48

Disadvantages of channel straightening

Answer 48

Flooding may happen downstream instead. Faster moving water causes erosion downstream

Question 49

What are embankments

Answer 49

Raised walls are built along river banks

Question 50

Advantage of embankments

Answer 50

River can hold more water so floods are less frequent

Question 51

Disadvantages of embankments

Answer 51

Very expensive Risk of severe flooding if water rises above level of embankment

Question 52

Flood relief channel

Answer 52

Channels are built to divert water around Built up areas to divert excess water if level gets to high

Question 53

Benefits of flood river channel

Answer 53

Gates on the channel mean the release of water can be contolled- reducing flood risk

Question 54

Disadvantages of flood relief channels

Answer 54

Increased discharge where the relief channel rejoins the river- causing flooding in that area

Question 55

Soft engineering

Answer 55

Schemes set up using knowledge of a river and its processes to reduce the effects of flooding Reduce effects of flooding

Question 56

What is Flood warning and preparation

Answer 56

Environment agency issues flood warning through forms of media eg radio, tv. Buildings are modified to minimise flood damage- residents also prepare sandbags and boards prior to flooding

Question 57

Benefits of flood warnings and preparation

Answer 57

Residents have more time to prepare and move possessions upstairs use sandbags etc This reduces impact of flooding

Question 58

Disadvantages of flood warnings and preparation

Answer 58

Warnings don’t prevent actual floods People may not have access to the warnings Expensive to modifying buildings

Question 59

Flood plain zoning

Answer 59

Restrictions prevent building on parts of flood zone that are likely to affected by a flood

Question 60

Benefits of flood plain zoning

Answer 60

Flood risk is reduced (fewer impermeable surfaces are created) Impact or flooding is reduced (No buildings to damage)

Question 61

Disadvantages of flood plain zoning

Answer 61

Expansion of urban is limited Can’t help in existing buildings

Question 62

Planting trees

Answer 62

Planting trees in the river valley increases interception of rainwater

Question 63

Benefits of planting treesc

Answer 63

Discharge and flood risk decrease Vegetation reduces soil erosion- provides habitats for wildlife

Question 64

Disadvantages of planting trees

Answer 64

Less land available for farming

Question 65

River restoration

Answer 65

Making river more natural, by removing man made levees, so plain can flood naturally

Question 66

Benefits of river restoration

Answer 66

Discharge is reduced so there’s less risk of flooding downstream Little maintenance is needed

Question 67

Disadvantages of river restoration

Answer 67

Local flood risk can increase. Especially if nothing is done to prevent flooding