Rivers

Question 1

What is the upper course of a river like?

Answer 1

It is at the top of a river where there are steep valleys receiving high amounts of rainfall each year, It is fast flowing and has a high carrying capacity so often contains lots of sediment. Valleys are often V-shaped

Question 2

What is the middle course of a river like?

Answer 2

It is where the river starts to meander around the landscape, where there is a lower gradient and good farmland. The water flows slower but there are much higher quantities of water. Valleys are often U shaped.

Question 3

What is the lower course of a river like?

Answer 3

This is where the river widens and turns into an estuary. It is deep. It has very high quantities of water and a low gradient so is useful for ports. This means that cities are often built next to them as they are flat and useful in trading but have large flood plains. It is often _/ shaped.

Question 4

Where is a river’s discharge at the highest?

Answer 4

At the lower course where the river is wide and contains lots of water.

Question 5

what is the sediment like at each stage of the river?

Answer 5

Upper course = large and angular
middle course = small and less angular
Lower course = very small and round

Question 6

What is attrition?

Answer 6

When rocks in the water crash into each other, the sides and bottom of the river causing them to get smoother and smaller.

Question 7

What is corrosion?

Answer 7

Where the rock chemically reacts with the water and starts to dissolve,

Question 8

What is hydraulic action?

Answer 8

Where air gets trapped in the banks of rivers and explodes causing them to break down.

Question 9

What is abrasion?

Answer 9

When rocks in the water hit against the river sides and breaks them down.

Question 10

What is solution?

Answer 10

Soluble sediment dissolved in river water

Question 11

What is suspension?

Answer 11

Where small particles are suspended in fast flowing water.

Question 12

What is traction?

Answer 12

Where large boulders roll slowly along the river bed.

Question 13

What is saltation?

Answer 13

Where small particles bounce along the river bed.

Question 14

What is soil creep?

Answer 14

Little bits of soil moving slowly downhill

Question 15

What are landslides and mudflow?

Answer 15

They are forms of slumping where large volumes of material go down a hill.

Question 16

What is mass movement?

Answer 16

Material moving downhill due to gravity.

Question 17

what does a river’s hydrograph show?

Answer 17

It shows how a river responds to a rainstorm. The bar graph at the bottom shows the amount of rainfall and the line shows the river discharge in meters cubed per second. The bottom shows the lag time. The shorter the lag rime and steeper the rising limb, the greater the risk of flooding.

Question 18

What is meant by a river drainage basin?

Answer 18

It is the area of land drained by a river where there is high rainfall and often steep slopes. The edge of it is known as the watershed. It is like a basin as where the water flows out is like the plug hole.

Question 19

What is river discharge and how is it calculated?

Answer 19

It is the volume of water flowing through a river at a given point. It is measured in cumecs (cubic meters per second)

Question 20

How is a meander formed?

Answer 20

It is formed when fast flowing water from a river erodes away the outside of a bend through abrasion. The then slower flowing water on the inside of the bend deposits sediment on the inside of the bend causing it to meander.

Question 21

What is an oxbow lake and how is it formed?

Answer 21

An oxbow lake is where a meander is cut off from a river and is formed when a bend is eroded away so much that it cuts through the land into another part of the river and deposited sediment separates the oxbow lake from the rest of the river.

Question 22

What are flood walls and what are the advantages and disadvantages of using them?

Answer 22

They are high walls built alongside a river to increase its capacity and prevent flooding. Pros- they are one-off costs and are useful in city centres where space is limited. Cons- they disperse water quickly and can increase flood risk downstream.

Question 23

What are embankments/levees and what are the advantages and disadvantages of using them?

Answer 23

Embankments raise the levels of river banks that are often built at a distance from the river to further increase the capacity. Pros- they can be made to blend in with the environment, protect houses and businesses. Cons- Water can go over the top or they can burst causing greater damage.

Question 24

What is dredging and what are the advantages and disadvantages of using it?

Answer 24

It is dredging (removing mud/rubbish/weeds from the seabed) to increase river flow and the capacity. Pros- protects people living near rivers and does not damage the environment. Cons- it is expensive and must be done every year and increases flood risk downstream.

Question 25

What is flood plain retention and what are the advantages and disadvantages of using it?

Answer 25

The level of flood plains are lowered and their surfaces are restored to shrubs or grassland so that they can retain water over a period and release it slowly into the river. Pros- it reduces flood risk and looks natural. Cons- it is expensive and can’t be built in most urban areas due to a lack of space.

Question 26

What is river restoration and what are the advantages and disadvantages of using it?

Answer 26

Meanders are built to lengthen the river and slow down water coming down. Building materials can be shipped away and replaced with trees and sediment. Pros- improves ecology and is better for the environment. Cons- sediment can just be washed away again so isn’t that effective.

Question 27

Give examples of soft engineering and hard engineering flood defences.

Answer 27

Hard- flood walls, levees, dredging

soft- floodplain retention, river restoration