Water on the Land

Question 1

What are the four processes of Erosion in a river?

Answer 1

Abrasion
Attrition
Solution
Hydraulic Action

Question 2

What are the four processes of Transportation in a river?

Answer 2

Traction
Saltation
Suspension
Solution

Question 3

Explain what Abrasion means

Answer 3

The river carries sand, silt and rocks and boulders at high flow, the material rubs against the river bed and erodes it.

Question 4

Explain what Attrition means

Answer 4

The load being carried by the river collides and rubs against each other and gets smaller and rounder.

Question 5

Explain what Solution (erosion) means

Answer 5

Rock minerals dissolves into the river water.

Question 6

Explain what Hydraulic Action means

Answer 6

The force of the water removes material from the bed and banks of the river.

Question 7

Explain what Traction means

Answer 7

Large boulders roll along the river bed (needs most energy)

Question 8

Explain what Saltation means

Answer 8

Smaller pebbles are bounced along the river bed, picked up and dropped off as the river flow changes

Question 9

Explain what Suspension means

Answer 9

Finer sands and silt particles are carried along in the rivers flow

Question 10

Explain what Solution (transportation) means

Answer 10

Minerals are dissolved into the water and carried along in the flow (needs least energy)

Question 11

Define alluvium

Answer 11

Material deposited or transported by a river

Question 12

Give two factors that can affect deposition

Answer 12

1. A fall in volume of a river like in a drought

2. A reduction in velocity on the inside of a bend

Question 13

What are the three courses of a river?

Answer 13

Upper, Middle and Lower

Question 14

Give four features of the upper course

Answer 14

1. V shaped valley
2. Vertical erosion
3. V shaped channel
4. Interlocking spurs

Question 15

Give three landforms in the upper course

Answer 15

1. Waterfall
2. Rapid
3. Gorge

Question 16

How is a V shaped valley formed?

Answer 16

River erodes vertically
Leaves very steep valley sides
River erodes and transports the material in the valley widening it into a V shape

Question 17

How is a gorge formed?

Answer 17

When the waterfall erodes the less resistance rock with abrasion and hydraulic action it leaves an overhang of more resistant rock that eventually collapes when it is no longer supported by the less resistance rock. This process of undercutting and collasping repeats and retreats upstream forming a gorge.

Question 18

How is a waterfall formed?

Answer 18

Less Resistant (LR) rock is eroed by hydraulic action and abrasion
MR rock at the top of the waterfall does not erode and is left overhaning
Eventually the overhang collapses, because it is not supported by the LR rock
A plunge pool is formed at the bottom of the waterfall, by hyrdaulic ation erosion as the water his the bed
Rocks in the plunge pool are worn by attrition
Gradually the waterfall retreats up stream to form a gorge

Question 19

Give four landforms of the middle course

Answer 19

1. Flood Plain
2. Meanders
3. River Cliff
4. Slip off slope

Question 20

Give three charactersitics of the middle course

Answer 20

1. Lateral erosion
2. Depostion
3. Wider and flatter

Question 21

Give two landforms of the lower course

Answer 21

1. Natrual levees

2. Ox boe lakes

Question 22

How is a meander formed?

Answer 22

The river has a faster current on the outside bend
The force of the water erodes and undercuts the outside bend by abrasion, forming a river cliff
On the inside bend the current is slower
Sand and small pebbles are depostied creating a slip off slope
The meander migrates across the land as the process repeats

Question 23

How are ox boe lakes formed?

Answer 23

Erosion on the outside bend of the meander and depostion means that the meander neck becomes narrower
Eventually the neck is broken up because it is quicker for the water to go in a straight channel than round a meander
This cuts of the meander bend
Allivium is deposted, which seals of the old meander forming an ox boe lake
Gradually the meander drys up because it has no water supply (apart from the rain)

Question 24

How does a meander migrate across a flood plain?

Answer 24

Lateral erosion means the meander gets bendier as it erodes and depostits more, and the neck gets narrower.

Question 25

Give two reasons why some rivers are able to carry a greater amount of load than others

Answer 25

1. Volume of water- the greater the volume the more load it can carry 2. Velocity- a fast flowing river has more energy to transport larger rocks

Question 26

Under what conditions is a river likely to deposit some of the load it is carrying?

Answer 26

1. A reduction in velocity or speed at the inside of a meander 2. A fall in the volume of a river, for example after a draugh

Question 27

Give 5 physical causes of flooding

Answer 27

1. Seasonal rainfall 2. Saturated ground 3. Snow melt 4. Frozen ground 5. Steep slopes by river

Question 28

Give 4 human causes of flooding

Answer 28

1. Building on flood plane 2. Deforestation 3. Dams bursting 4. Impermable surfaces eg tarmac, concrete

Question 29

What is the peak rainfall on a Hydrograph?

Answer 29

Peak Rainfall is the highest amount of rain in a storm.

Question 30

What is the peak discharge on a Hydrograph?

Answer 30

Peak Discharge is the greatest amount of water passing one point.

Question 31

What is the lag time on a Hydrograph?

Answer 31

Lag time is the difference between peak rainfall and peak discharge.

Question 32

Define Discharge

Answer 32

Discharge is the volume of water passing one point a second.

Question 33

What is a flashy flood?

Answer 33

When the flood has a shorter lag time and the river is more likely to flood faster .

Question 34

Give three soft managment strategies for flooding

Answer 34

1. Aforestation 2. Floodplain zoning 3. Environment Agency

Question 35

Give three hard managment strategies for flooding

Answer 35

1. Dams and reservoirs 2. Dredging 3. Straighening rives

Question 36

What is floodplain zoning and give an advantage and disadvantage?

Answer 36

Areas near to the river cost less than houses further away. + not as many houses will be built on the floodplain making the surface more permable - Homes are already built there and they will loose their value

Question 37

What is afforestation and give an advantage and disadvantage?

Answer 37

Trees are grown near the river to absorb the water when there is a high rainfall. +It is low cost and enhances the environmental quality of the drainage basin. - There may be building and no space go grow trees.

Question 38

What is the environment agency and give an advantage and disadvantage?

Answer 38

Houses in flood risk zones are monitored and warned if there is a risk of flooding. +People can prepare for a flood and evacuate.

Question 39

What are dams are reservoirs?

Answer 39

Huge concrete structures that block rivers meaning the flow of the river can be controlled to prevent flooding during peak rainfall.

Question 40

Give an advantage and disadvantage of dams and reservoirs

Answer 40

+ Hydro-electric Power can be produced when water is released through the dam. - Lakes can form behind dam and people have to be displaced. Sediment is deposited behind the dam.

Question 41

What is straighening and dredging rivers?

Answer 41

Straightening meanders by digging shorter channels, so water is it hanging round and gets to the sea quicker and digging deeper channels so the river can hold more water.

Question 42

Give an advantage and disadvantage of traighening and dredging rivers

Answer 42

+ The river can hold more water before it bursts it's banks. The water can reach the sea quicker so it can not flood big areas. - Both may cause floods to occur nearer to the mouth. They are expensive to build and maintain and have an environmental impact.

Question 43

What is a water defficet?

Answer 43

Where there is not enough water

Question 44

What is a water surplus?

Answer 44

Where is more water than needed in an area