Rivers: a revision session
River facts
River landforms are formed by erosion,
transportation and deposition
The main processes of river erosion are:
abrasion, hydraulic action, attrition and
solution. These operate best at times of
flood.
A river’s load is transported by solution,
suspension, saltation and traction
Parts of a river’s course
A river can be subdivided into its upper, middle
and lower course. Each part will have
distinctive landforms and characteristics.
• Upper: potholes, V shaped valleys, waterfalls
and interlocking spurs.
• Middle: slip off slopes, river cliffs, meanders
and asymmetric cross section
• Lower: flood plains, levees, ox bow lakes and
deltas
Flooding
• Rivers will flood when the discharge or flow is
greater than the channel can cope with.
• Deforestation and the building of roads and
houses on the flood plain increases surface
runoff and reduces infiltration, increasing flood
danger.
• Flooding can be reduced by building
reservoirs, levees, and relief channels.
• Straightening the channel will increase the
Flood management
Two case studies :
• MEDC; Boscastle causes effects and
‘solutions
• LEDC; Mozambique, causes, effects
and ‘solutions’.
Future
• There has been a move away from ‘hard’
solutions, e.g. the construction of levees to
‘soft’ solutions e.g. flood plain zoning.
• This is particularly true in LEDCs where
they cannot afford the costs of large
schemes