A22 Rivers

Question 1

Domestic demands for river

Answer 1

Provides essential need for settlement

Washing cooking cleaning drinking

Proximity to river is major location factor

Across Europe individuals use 10x more water than 150 years ago

Question 2

Demands on river for agriculture

Answer 2

Farming uses more fresh water than all their human activities put together

30% of all farmland in the world requires irrigation

Flooding provides alluvial sediment rich in nutrients to enhance quality of soil on floodplain

Question 3

Demands for river for industry

Answer 3

Heaven manufacture makes high water demands

On average 30,000 litres of water used for production of a car

Rivers and canals make routes for industrial transportation

Question 4

Demands on river for energy production

Answer 4

Thermal power stations such as coal gas peat and nuclear require large amounts of water

HEP systems can be established which is a cheaper and renewable source of energy

Question 5

Demands on river for leisure activities

Answer 5

Recreational activities associated with river and valley systems

Question 6

What is river management

Answer 6

Steps taken to manage a river, usually to reduce flooding and control the river channels

Question 7

What is channelisation

Answer 7

Tern that describes deliberate modification of natural river channels.

Involves changes to width doe or the plan form (vertical view)

Common reasons for channelisation - flood control, land drainage, navigation and erosion problems

Question 8

Aims of channelisation

Answer 8

Increase flow velocity of channel

Increase carrying capacity of channel

Question 9

Methods of channelisation

Realignment/diversion

Answer 9

Creates straighter shorter route with steeper gradient

Meanders in channel are cut through an filed into produce straighter channel with a steeper downstream profile

Speeds up water flow down river

Question 10

Resectioning

Answer 10

Increases river velocity and efficiency

Reduces friction and prevents sediment storage

Chanel cross section enlarged either by widening through excavating the banks or deepened by dredging river bed

Create a more energy efficient trapezoid shaped cross section with broad bed and steep banks

Question 11

Revetments (walls/gabions)

Answer 11

Protects bank from erosion and controls meander migration

Increasing river velocity increases its opportunity to erode beds and banks

Both upstream and downstream channels may become unstable and require protection

Question 12

Wind dykes

Answer 12

Deflects thaiweg keeping channel clear