Rivers Flashcards
Define:
- Drainage Basin
- Source
- Tributary
Drainage Basin = Area drained by river
Source = Start of river (spring/lake)
Tributary = Small river joining on to big river
Define:
- Confluence
- Mouth/Estuary
- Watershed
Confluence = Where 2 rivers meet
Mouth/Estuary = Where rivers meet sea
Watershed = Boundary between drainage basins
What is the difference between lateral and vertical erosion?
Lateral Erosion = channel widening
Vertical Erosion = channel deepening
Name the 3 main types of weathering
Physical - Freeze thaw
Chemical - Acid rain
Biological - Roots cracking rocks
Name the 3 main types of mass movement
Slumping
Rockfall
Soil Creep = soil particles move down slope due to gravity
Describe what happens to each of these river characteristics as the river goes downstream
Width, Depth, Velocity, Discharge, Gradient, Valley Shape
- Widens
- Deepens
- Velocity increases
- Discharge increases
- Flattens
- V shape -> U shape -> flat
Name 3 characteristics of an upper course river
Vertical erosion
Steep
Narrow
Name 2 landforms found in the upper course of a river, and how they form
Interlocking Spurs - low energy river floes around valley sides (spurs) -> interlocking
Waterfalls - Vertical erosion where hard, resistant rock is over less resistant rock
Name 2 landforms found in the middle course of a river, and how they form
Meanders:
- River erodes laterally -> large bends
- Bends get bigger -> meander
- Inner bend - slow current, high disposition -> slip-off slope
- Outer bend - fast current, high erosion -> river cliff
Oxbow Lakes:
- Erosion -> meander neck to narrow
- Outer bends meet, river cuts through
- Meander cut off by main river -> oxbow lake
Name 2 landforms found in the lower course of a river, and how they form
Flood plains:
- River carried lots of sediment
- Floods -> excess water spills over surrounding area
- Deposits sediment -> flood plain
- Floodplain shaped by lateral erosion of meanders
Levees:
- River floods -> sediment deposited on bank (heaviest first)
-
Name 4 physical causes of river flooding, and how they lead to flooding
Rainfall Intensity:
- Lots of rainfall in short time -> soil infiltration
Geology:
- Impermeable rocks can’t absorb water
Snow Melt:
- Snow melts in spring -> more water
Drainage Basin:
- Steep valleys and tributaries collect water
All causes lead to:
Excess water -> surface runoff -> more water than channel can hold -> flooding
Name 3 human causes of river flooding, and how they lead to flooding
Deforestation:
- Less plants to absorb water
Climate change:
- Melting ice sheets and glaciers -> more water in glaciers
Urbanisation:
- Rain forced to flow quickly into sewers
- Man made surfaces = impermeable
All causes lead to:
Excess water -> surface runoff -> more water than channel can hold -> flooding
Give 2 social impacts of the 2011 mississippi flooding
Outbreak of water borne diseases
Homes flooded
Give 2 economic impacts of the 2011 mississippi flooding
Insurance, fuel and food prices increase
Expensive fertilisers needed to replace washed away nutrients
Give 1 environmental impact of the 2011 mississippi flooding
Crops and farmland are destroyed
Explain 3 hard engineering methods used to manage the mississippi river
Levees built since 1700s
River straightened
Floodways and cut offs divert water
Explain 4 soft engineering methods used to manage the mississippi river
Insurance scheme regulates land use on floodplain
Flooded agricultural land bought to store excess water
Resorting upriver wetland areas - soak up extra rainwater
Government funding for farmers. Land -> wildlife conservation reserved & water storage areas
Give 1 reason how planning and 2 reasons how prediction can reduce the impact of flooding
Planning: Land use zoning
Prediction: Environment Agency monitors rivers
- forecast potential floods
- give advanced warnings of flooding
Give 4 reasons how prevention and 4 reasons hoe education can reduce the impact of flooding
Prevention - Reduce water damage to homes:
- Use ceramic tiles
- Raise height of electrical sockets on walls
- Install heating systems on upper floors
- LICS build homes on stilts above water levels
Education - spread information:
- Leaflets and advertising
- Posting information on website
- Phone helplines
- Organising flood drills
Explain the advantages and disadvantages of 3 methods of soft engineering
Afforestation - planting trees in drainage basin:
Ads - Vegetation soaks up water
- Provides habitats
Dis - Could use land for other purposes
Land Use Zoning:
Ads - Homes and expensive projects can be
located in low risk areas
- Less important located in high risk areas
Dis - Public access may be difficult
- May cause planning problems elsewhere
Washlands - areas allowed to flood:
Ads - Cheap
- Less visual pollution
Dis - Floodplain can’t be used for other purposes
Explain the advantages and disadvantages of 3 methods of hard engineering
Flood relief channels - extra channels to carry extra water:
Ads - Excess water taken away, stopping it from
flooding nearby land
Dis - Visually unattractive
- Only needed during flood risk
- Expensive to build and maintain
Channelisation - depeening/widening river channel:
Ads - Allows water to quickly flow away from
flood risk areas
Dis - Visually unattractive
- More water taken downstream, increasing
flood risk to other settlements
Embankments - levees built along river banks:
Ads - Use natural materials, so blend in
- Prevent water moving into flood risk areas
Dis - Flood water can spill in extreme conditions
- Can burst under pressure -> widespread
damage
