RIVERS

Question 1

How does a rivers cross profile over its course?

Answer 1

Upper course - narrow and deep (V)
to
Lower course - wide and shallow (U)

Question 2

How does a rivers long profile over its course?

Answer 2

Steeper in the upper course and slowly levels out (gradient decreases).

Question 3

How does vertical and lateral erosion change the cross profile of a river.

Answer 3

Vertical erosion makes the river deeper (mainly in upper course, V shape).
Lateral erosion makes the river wider (middle and lower course).

Question 4

What are physical causes of river flooding?

Answer 4

• Heavy rainfall
• Long periods of rain
• Impermeable rock

Question 5

What are human factors that increase the risk of river flooding?

Answer 5

• Urbanisation (impermeable surfaces in towns)
• Deforestation (removing trees increases surface run-off)

Question 6

What is river discharge?

Answer 6

River discharge is the volume of water flowing through a river channel.

Question 7

What are factors that can increase river discharge?

Answer 7

Impermeable surfaces
Heavy rainfall
Deforestation
Long periods of rain

Question 8

What do dams do to stop flooding (hard engineering)?

Answer 8

Dams - traps water and can release it in a controlled way.

Question 9

What does river straightening do to stop flooding (hard engineering)?

Answer 9

River straightening - straightening the river speeds up the water, so high volumes can pass through an area quickly, therefore reducing the chances of a flood.

Question 10

What do embankments do to stop flooding (hard engineering)?

Answer 10

Embankments - embankments raise the banks of a river so that it can hold more water.

Question 11

What do flood relief channels do to stop flooding (hard engineering)?

Answer 11

The 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

Question 12

What do flood warnings do to stop flooding (soft engineering)?

Answer 12

Warn people so they can protect their properties and save possessions.

Question 13

What does floodplain zoning do to stop flooding (soft engineering)?

Answer 13

Allowing only certain land uses on the floodplain reduces the risk of flooding to houses and more important buildings.

Question 14

How are meanders formed?

Answer 14

Erosion on the outside bend (the arc).
On inside bend the river flow is slower so sediment drops (deposition).

Question 15

How are ox-bow lakes formed?

Answer 15

An oxbow lake starts out as a meander in a river. A lake forms as the river finds a different, shorter, course.

Question 16

How are levees formed?

Answer 16

The natural movement of a body of water pushes sediment to the side. This makes the banks of a river are often slightly elevated from the river bed. The banks are made of sediment, silt, and other materials pushed aside by the flowing water.

Question 17

How are waterfalls formed?

Answer 17

Waterfalls often form in the upper stages of a river where it flows over different bands of rock. It erodes soft rock more quickly than hard rock

Question 18

How are steep-sided gorges formed?

Answer 18

Streams carve through hard layers of rock, breaking down or eroding it. Sediment from the worn-away rock is then carried downstream. Over time, this erosion will form the steep walls of a gorge.

Question 19

Why do interlocking spurs form?

Answer 19

Because in the upper course of a river it lacks the power to erode laterally so it winds around the high hillsides which interlock with each other

Question 20

What are flood plains?

Answer 20

The wide valley floor on either side of a river that occasionally floods
It builds up when water floods, loses energy and deposits material

Question 21

What are estuaries?

Answer 21

Near the river mouth
Tides rise and deposit silt and sand
Overtime more mud builds up creating large mudflats

Question 22

What can increase the flood risk of a river?

Answer 22

Prolonged rainfall
Heavy rainfall
Rock type (impermeable)
Land height
Land use

Question 23

What are estuaries?

Answer 23

Where the river meets the sea
River is tidal so the sea retreats so the volume of the water in the estuary is reduced
Less water so the river deposits silt to form mudflats