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Physical Geography: Fluvial Processes, Patterns and Landforms - Coggle…

- - - - Gradient
      - Discharge
      - Shape of river channel
      - Roughness of the river channel
- - - - V-shaped valley, e.g. River Liffey
        
        Processes: vertical erosion, hydraulic action, abrasion, weathering and mass movement
        
        Steep sides, narrow valley floor
        
        Vertical erosion
        
        Hydraulic action
        
        The river’s load further erodes and abrades the valley
        
        Deepens the riverbed and creates steeper sides
        
        Sides are then weathered and mass movement
        
        Mass movement causes the sides of the valley to move downslope into the river
        
        Eddying creates potholes
        
        Interlocking spurs
      - Waterfall, e.g. Powerscourt
        
        Processes: differential erosion, abrasion, hydraulic action, headward erosion, eddying
        
        Youthful stage
        
        Interruption in the river’s profile
        
        Created where a band of hard rock lies next to a layer of soft rock
        
        Differential erosion, hydraulic action, abrasion
        
        Soft rock is eroded and transported downstream
        
        Leaves hard, more resistant rock elevated and standing out
        
        As the process continues the drop over the more resistant rock becomes steeper
        
        Flow over the resistant rock forms a waterfall
        
        A series of rapids are often formed above the area of resistant rock
        
        A plunge pool forms at the base of the waterfall
        
        Deepens as a result of eddying
        
        Overhang created
        
        Headward erosion, gorge
        
        Glaciation
        
        Tectonic uplift
        
        Rejuvenation
    - - Meanders, e.g. River Shannon
        
        Processes: lateral erosion, hydraulic action, bank caving, deposition
        
        Curves or bends in the river’s course
        
        Corkscrew-type flow
        
        Water on the concave bend of a meander is deep; the river moves faster and erosion occurs
        
        Water on the convex bend of a meander is shallow; the river moves slowly and deposition takes place
        
        Hydraulic action, abrasion, cavitation
        
        River cliff
        
        River beach or point bar
        
        Migrate
        
        Bluff line
    - - Floodplains, e.g. River Shannon
        
        Processes: flooding, deposition, lateral erosion
        
        Flat, low-lying land
        
        Combination of erosion and deposition
        
        Meanders swing from side to side as far as bluff line
        
        Heaviest material deposited on top of river banks
        
        Finest, lightest particles of the river’s load carried by suspension away from the river channel
        
        Alluvium deposited on the floodplain
        
        Rich fertile areas for farming
      - Oxbow lakes, e.g. River Liffey
        
        Processes: deposition, hydraulic action, lateral erosion
        
        Horseshoe-shaped lake
        
        Formed when a meander is cut off from the river
        
        Lateral erosion takes place on the outer bend
        
        Deposition occurs on the inside bend
        
        Narrow neck is eventually cut through, hydraulic action
        
        Deposits its load, leaving a meander loop isolated
        
        Oxbow lake is formed
        
        Eventually dries up, forming a mort lake
      - Levees, e.g. River Barrow
        
        Processes: flooding, deposition
        
        Raised banks of alluvium
        
        Flooding river flows over a wider floodplain
        
        Speed is reduced and its ability to transport is also reduced
        
        Deposition occurs
        
        Heavy material is deposited first whilst lighter material flows further out over the floodplain
        
        Leads to the formation of raised banks
        
        Back swamps
        
        Artificial levees
      - Deltas, e.g. Upper Lake, Glendalough
        
        Processes: deposition, flocculation, sorting
        
        Flat area of alluvium deposited at a river mouth
        
        River loses speed and its energy to transport recedes
        
        Deposition of alluvium
        
        Alluvium builds up and becomes visible above the water
        
        Bottomset beds are composed of fine deposits – are carried/transported out furthest to sea
        
        Foreset beds are composed of coarser deposits – are deposited close to the river mouth
        
        Topset beds are composed of differing deposited material – some fine, some coarser, e.g. silt and sand
        
        Lacustrine deltas form where rivers enter lakes
        
        Marine deltas form where rivers enter the sea. There are three main types of marine delta:
        
        Arcuate delta
        
        Estuarine delta
        
        Bird’s foot delta
- - - - Barrier to prevent flooding
      - Control the flow of water
    - - Increased deposition on riverbed
      - Deposition on floodplains reduced
      - Levees can fail
  - - - Generation of electricity
      - Renewable energy
      - Supply of water
      - Controlling the flow of water
      - The reservoir can be used for recreational purposes and for aquaculture
    - - Relocation of people
      - Natural flooding does not occur downriver
      - Reduction in the number of species living in the river ecosystem
      - Flooding 2015–2016, economic cost as water released from the dam
  - - - Efficient water transport
      - Deeper channels allow bigger vessels
      - Irrigation purposes
      - Controls the flow of water
    - - Increased gradient and velocity of river
      - Damage to ecosystem and fish life
      - Reduce alluvium deposits on floodplain