Rivers processes

Question 1

Describe the long profile of a river

Answer 1

Starts steep in the upper course and then becomes increasingly flat towards the lower course

Question 2

How does the cross profile of a river change from source to mouth?

Answer 2

Starts narrow and V shape, gets wider with a flatter bottom towards the mouth

Question 3

What is the Bradshaw model and what does it show?

Answer 3

How a river changes from source to mouth- quicker, wider, deeper, smaller particles, more discharge

Question 4

Why does a river deposit material?

Answer 4

on inside of meanders when there’s more friction, when the river slows down and has high capacity. Overloaded with sediment, might be an obstruction in the river

Question 5

What is lateral erosion and where does it take place?

Answer 5

Middle course to produce wide valleys

Question 6

Which part of the river’s course do you find waterfalls and gorges?

Answer 6

Upper course

Question 7

What role does rock type play in the formation of waterfalls and gorges?

Answer 7

Band of hard rock overlays soft rock. Soft rock erodes quicker causing an overhang.

Question 8

What are interlocking spurs and where are they found?

Answer 8

Hillsides that interlock as the river winds around them. Found in upper course

Question 9

What is a meander?

Answer 9

bend in a river

Question 10

Why is the current faster on the outside of the bend?

Answer 10

The river is deeper, there is less friction to slow the water down

Question 11

Describe how oxbow lakes are formed

Answer 11

Erosion causes the outside bends of a meander to get closer together until there’s only a small bit of land left. During times of flood the river breaks through so the river takes the shortest course. Material is deposited along the river banks cutting off the meander.

Question 12

What is a flood plain and a levee?

Answer 12

A floodplain- wide valley floor on either side of a river in the lower course, Levee- deposited mounds of material either side of the river in the lower course

Question 13

Why does the water level in an estuary change over the course of a day?

Answer 13

Water is tidal so water rises and falls with the tide. When it’s high the water flood the valley and silt is carried there.

Question 14

What is the name of the waterfall along the River Tees?

Answer 14

High Force

Question 15

Name 2 ways water gets into a river

Answer 15

Rainwater can flow overland- surface runoff, soak into the ground (infiltration) and flow through the soil to get into the river or directly into the river. Percolation - where water soaks through rocks. Through flow - lateral movement of water through rock.

Question 16

What is the falling limb and rising limb of a hydrograph?

Answer 16

Falling limb shows the decrease in river discharge as the river returns to normal level. Rising limb is the river level increasing to peak discharge after the rainfall event

Question 17

Name 2 physical factors that would increase the risk of flooding

Answer 17

Prolonged rainfall, steep slopes, impermeable rocks. Saturated ground. Rapid snowmelt

Question 18

What is the lag time in a hyrdograph? Why is there a lag time?

Answer 18

The time between peak rainfall and peak discharge. There’s a delay between peak rain and peak discharge as the water travels slowly through soil and comes in different routes to reach the river

Question 19

How would changing land use increase flood risk?

Answer 19

The building materials made from impermeable rock increasing the speed of surface run off. man made drains also channel water quickly into the river. Deforestation.

Question 20

What are river embankments?

Answer 20

Raised walls along river banks that allow the river to hold more water

Question 21

How might channel straightening affect villages further down?

Answer 21

it will reach the villages downstream quicker leading to increased erosion and flood risk

Question 22

Why was the flood management scheme required in Boscastle?

Answer 22

Severe flash flooding 2004. Damaged homes and access to work was restricted - tourism was severely effected.

Question 23

Describe the hard engineering that was used in Boscastle

Answer 23

Widening the river, flood culverts, raised height of the bridge. Braided the river upstream. Raised the height of the car park.

Question 24

Describe the soft engineering that was used in Boscastle

Answer 24

Coppicing of trees

Question 25

What are the environmental issues associated with flood management scheme in Boscastle?

Answer 25

Many trees and large area of rare grassland will be removed and replanted. Fish and aquatic life were disturbed when the river was widened.