This presentation is a cool resource for doing river revision, especially if you are doing A-levels in Geography. Here, we will talk about river formation and all related processes that happen with rivers

1. Rivers, floods and management
Rivers, floods
and management

2. Rivers, floods and management
The drainage basin hydrological cycle

3. Rivers, floods and management
River discharge
The storm hydrograph

4. Rivers, floods and management
River discharge
What factors might result in a ‘flashy’ hydrograph?
• short-lived but intense rainfall
• impermeable underlying rock such
as granite
• steep relief
• urban area, where water is
channelled through drains to the
stream
• small round drainage basin

5. Rivers, floods and management
River discharge
What factors might create a hydrograph like this?
• dense woodland vegetation
• high infiltration capacity of soil
• permeable underlying rock, such as
limestone
• elongated drainage basin

6. Rivers, floods and management
The long profile

7. Rivers, floods and management
The Hjülstrom curve

8. Rivers, floods and management
Amanda Barker
An upper course channel

9. Rivers, floods and management
Amanda Barker
A middle course channel

10. Rivers, floods and management
Amanda Barker
A lowland channel in flood

11. Rivers, floods and management
High Force waterfall
• vertical erosion
(by hydraulic action
and corrasion)
below the waterfall
deepens the plunge
pool
the resistant Whin
Sill and results in
headward erosion
John Pallister
• undercutting of the
softer rock leads to
eventual collapse of

12. Rivers, floods and management
The development of an oxbow lake

13. Rivers, floods and management
Reasons for formation of a delta
• the sediment load carried by the river is substantial
• the river has a large drainage basin
• the mouth of the river is located on a coastline where ocean currents and
tides are weak so the rate of deposition exceeds the rate of sediment
removal

14. Rivers, floods and management
Features related to rejuvenation
• knick points, rapids and
waterfalls
• river terraces
The city of Durham is built inside
an entrenched meander
Aerofilms
• incised meanders, both
entrenched and ingrown

15. Rivers, floods and management
Flooding
Physical causes of flooding
• excessive precipitation over
a long period of time
• the nature of the drainage
basin
• intensive precipitation over
a short period of time
• relief
• snowmelt
• natural vegetation
• climatic hazards such as
hurricanes
• rock and soil type

16. Rivers, floods and management
Flooding
Influence of human activities on flooding
• Urbanisation creates impermeable surfaces so reducing infiltration.
Surface water is therefore transported more rapidly through drains to
the river.
• Deforestation reduces interception and increases runoff.
• Some methods of river management, such as channelisation, increase
flood risk downstream.
• Global warming leads to more extreme rainfall events.

17. Rivers, floods and management
Flooding
Areas of high flood risk in England and Wales

18. Rivers, floods and management
Flooding
Responses to flooding
Short-term responses:
Long-term responses:
• media broadcasts of information
• government and/or foreign aid
• emergency relief, rescue, shelter,
food
• disaster planning for the future
• armed services for evacuation and
building emergency defences
• flood management programmes

19. Rivers, floods and management
Flooding
Examples of hard engineering
• channelisation, to raise, straighten or strengthen banks
• dams and weirs
• diversion channels
• dredging
• retention basins and balancing lakes
• artificially raising the height of the floodplain

20. Rivers, floods and management
Flooding
Examples of soft engineering
• afforestation
• floodplain zoning
• land-use management, e.g. contour ploughing
• wetland and riverbank conservation
• river restoration
• improved forecasting and warning