Rivers

Question 1

What are Dams and reservoirs?

Answer 1

A barrier built across the valley to interrupt river flow and create a man-made lake (reservoir)

Question 2

Cross profile

Answer 2

Side to side cross-section of a river channel and or valley

Question 3

What is Discharge?

Answer 3

The quantity of water that passes a given point on a stream or river bank within a given period of time

Question 4

Embankments

Answer 4

Raise banks constructed along the river they effectively make the river deep so It can hold more water

Question 5

Estuary

Answer 5

The title mouth of the river where it meets the sea wide banks of deposited mud are exposed at low tide

Question 6

What is a Flood?

Answer 6

when a river discharge exceeds river channel capacity

Question 7

Floodplain

Answer 7

The relatively flat area forming the valley floor on either side of the river channel

Question 8

Floodplain zoning

Answer 8

This attempts to organise the flood defences in such a way that land near the river and often floods is not built on

Question 9

Flood relief channels

Answer 9

Building new artificial channels which are used when a river is close to maximum discharge

Question 10

Flood risk

Answer 10

The predicted frequency of floods in an area

Question 11

Flood warning

Answer 11

Providing reliable advance information about possible flooding

Question 12

Fluvial processes

Answer 12

Processes relating to erosion transport and deposition by river

Question 13

What is a Gorge?

Answer 13

A narrow steep sided valley often formed as a waterfall retreats upstream

Question 14

Attrition

Answer 14

When stones carried by the river knock against each other making a stone smaller and more rounded

Question 15

Hydraulic action

Answer 15

The force of the water hitting the river bed and banks

Question 16

Abrasion

Answer 16

When the load carried by the river repeatedly hits the bed and banks dislodging particles into the flow of the river

Question 17

Solution

Answer 17

When the river flows over limestone or chalk the rock is slowly dissolved

Question 18

Suspension

Answer 18

Fine, light material is held up and carried within the river flow

Question 19

Traction

Answer 19

Large boulders and rocks are rolled along the river bed

Question 20

Saltation

Answer 20

Small pebbles and stones are bounced along the river bed

Question 21

Upper course valley characteristics

Answer 21

-vertical erosion with hydraulic action, abrasion and attrition dominant processes
-traction and saltation at high flow
-load size is large and Angular
-V shaped valleys

Question 22

Middle course valley characteristics

Answer 22

-Channel is deeper and wider
-vertical erosion decreasing in importance, more lateral erosion and deposition
-suspension is the main transportation type
-load become smaller and less Angular

Question 23

Lower course Valley characteristics

Answer 23

-Channel is at its widest and deepest, and maybe tidal
-Deposition more important than erosion
-fine material deposited
-large amount of load but the size is very small and very rounded

Question 24

River Deposition

Answer 24

Deposition occurs when the velocity of a river decreases.

Question 25

Formation of an oxbow lake

Answer 25

Deposition on inside Bends, erosion on outside Bends

Question 26

Examples of hard engineering:

Answer 26

-Dams and reservoirs
-Channel straightening
-embankment
-flood relief channels

Question 27

Soft engineering

Answer 27

-wetlands and flood storage areas
-floodplain zoning
-River restoration
-preparing for floods

Question 28

causes of flooding: physical factors

Answer 28

precipitation:
-heavy rain
-prolonged rain
-snowmelt
Geology (rock type):
-impermeable
-Steep Slopes
-Low-lying land

Question 29

Causes of flooding: Human factors

Answer 29

Farming:
-removal of hedges
-intensive arable farming leaves soil bear
-disappearing fields
-urbanisation
-deforestation