841911
Rivers, Floods and Management 2
- River Landforms
- Waterfalls
- Bands of hard and soft
rock - the soft rock is
eroded easier and causes a
step
- Vertical erosion of soft rock causes waterfall
- Plunge pool and undercutting is caused - this causes a gorge
- Plunge pool and undercutting is caused - this causes a gorge
- Bands of hard and soft
rock - the soft rock is
eroded easier and causes a
step
- Potholes
- Small circular hollows in the river bed
- Formed by abrasion as turbulence swirls a
rivers bedload in circular motion, this causes an increased erosion
- Small circular hollows in the river bed
- Rapids
- Steep sections of river with turbulent flow
where several sections of hard rock are
present
- Steep sections of river with turbulent flow
where several sections of hard rock are
present
- Levees
- Natural, raised embankments formed as a river overflows its banks
- During a flood material is deposited as
energy is lost, the heaviest is dropped
first closest to the river bank
- Natural, raised embankments formed as a river overflows its banks
- Braiding
- When a rivers velocity drops, it
deposits material in the channel, this
causes it to be divided into smaller
winding channels
- When a rivers velocity drops, it
deposits material in the channel, this
causes it to be divided into smaller
winding channels
- Floodplains
- When a river overflows its banks, the
friction increases, this causes it to
lose energy and thus depositing its
fine silt across the flood plain
- When a river overflows its banks, the
friction increases, this causes it to
lose energy and thus depositing its
fine silt across the flood plain
- Deltas
- When a river reaches a slow moving
sea or lake, the energy is absorbed
and material is deposited
- When a river reaches a slow moving
sea or lake, the energy is absorbed
and material is deposited
- Waterfalls
- MEANDERS
- ALTERNATING POOLS AND RIFFLES at equally spaced intervals
- GREATER ENERGY IN DEEPER AREAS SO MORE EROSION OCCURS
- CONCENTRATED FLOW IS CAUSED ON ONE SIDE
- TURBELANCE INCREASES AND HELIOIDAL FLOW
OCCURS ( corkscrew effect)
- Erosion in deep end and deposition in
shallow end due to loss of energy
- Erosion in deep end and deposition in
shallow end due to loss of energy
- TURBELANCE INCREASES AND HELIOIDAL FLOW
OCCURS ( corkscrew effect)
- CONCENTRATED FLOW IS CAUSED ON ONE SIDE
- GREATER ENERGY IN DEEPER AREAS SO MORE EROSION OCCURS
- ALTERNATING POOLS AND RIFFLES at equally spaced intervals
- Rejuvenation
- When a river gains more
energy by movement of the
sea level or ground level
- Rise in Ground level
- Fall in Sea Level
- Rise in Ground level
- Knickpoints - sharp change in gradient
- Can form Waterfalls
- Can form Waterfalls
- River Terraces
- Former flood plains which have
been left above the level of
present-day flooding following
increased vertical erosion
- Former flood plains which have
been left above the level of
present-day flooding following
increased vertical erosion
- Incised Meanders
- When a river keeps its meandering course as
the vertical erosion increases. Deep, winding
valleys with steep sides.
- When a river keeps its meandering course as
the vertical erosion increases. Deep, winding
valleys with steep sides.
- When a river gains more
energy by movement of the
sea level or ground level
- Causes of Flooding
- Sparse Vegetation
- Less Interception occurs so more discharge
- Less Interception occurs so more discharge
- Impermeable Ground
- Infiltration cant occur so more surface runoff an more discharge
- Infiltration cant occur so more surface runoff an more discharge
- Steep slopes means the water reaches the river channel quicker
- High Drainage density
- Short Lag time, increasing discharge
- Short Lag time, increasing discharge
- Climate Change
- Monsoon Weather
- Monsoon Weather
- Sparse Vegetation
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