Rivers Flashcards

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1
Q

Description: Upper Course of a River

A

Near the source, the river flows over steep gradient from the hill/mountains. This gives the river a lot of energy, so it will erode the riverbed vertically to form narrow valleys.

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2
Q

Description: Middle Course of a River

A

Here the gradient gets gentler, so the water has less energy and moves more slowly. The river will begin to erode laterally making the itself wider.

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3
Q

Description: Lower Course of a River

A

Near the rivers mouth, it widens further and becomes flatter. Material transported is deposited.

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4
Q

Formation of a Waterfall + Gorge

A

1) Rivers flow over alternating rock types
2) Rivers erode softer types faster creating a step
3) Further hydraulic action and abrasion form a plunge pool beneath
4) Hard rock above is undercut leaving ‘cap rock’ which collapses providing more material for erosion.
5) Waterfall retreats leaving steep sided gorge.

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5
Q

Formation of Levees + Floodplains

A

When a river valley floods, silt is depositied on the valley floor. Closer to the rivers banks, the heavier materials build up to form natural levees.

  • Nutrient soil = good for farming
  • Flat land = ideal for building houses
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6
Q

Formation of Interlocking Spurs

A

The river swings around the ‘fingers’ of land to find the easiest route.

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7
Q

Formation of Ox-Bow Lakes

A

1) Erosion of outer bank forms river cliff. Deposition inner bank forms slip off slope
2) Further hydraulic acton and abrasion of outer banks, nck gets smaller.
3) Erosion breaks through neck, so river takes the fastest route, redirecting flow.
4) Deposition cuts off main channel leaving an oxbow lake.

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8
Q

Physical Causes of Flooding

A
  • Prolonged + Heavy Rainfall
  • Relief
  • Geology
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9
Q

Human Causes of Flooding

A

Land Use:

  • Impermeable substances used like concrete and tarmac = surface runoff
  • Deforestation reduces interception and increases runoff
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10
Q

Environmental Consequences of Flooding

A
  • Landslides
  • Soil Erosion
  • Loss of Habitats
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11
Q

Human Consequences of Flooding

A
  • Loss of Property + Belongings
  • Disruption to Business + Transport
  • Death/Injury
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12
Q

Definition: Precipitation

A

Moisture falling from clouds as rain, snow or hail

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13
Q

Definition: Interception

A

Vegetation preventing precipitation from reaching the ground

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14
Q

Definition: Surface Runoff

A

Water flowing over surfaces of the land into rivers

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15
Q

Definition: Infiltration

A

Water absorbed into the soil from the ground

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16
Q

Definition: Transpiration

A

Water lost through leaves of plants

17
Q

Description: Mechanical/Physical Weathering

A

Rock broken into smaller and smaller pieces by cold or heat - freeze thaw or onion skin weathering

18
Q

Description: Chemical Weathering

A

Slightly acidic rain seeps into rocks, attacks elements in rocks

19
Q

Description: Biological Weathering

A

Roots of trees grow into cracks and split rocks

Animals burrowing

20
Q

Stores in Hydrological Cycle

A
  • Atmosphere: Water vapour, tiny droplets
  • Land: Rivers, lakes, resovoirs, groundwater
  • Sea: ≈95% of Earths water, includes ice
21
Q

Description: Peak Discharge

A

The discharge of the river in a period of time

22
Q

Description: Lag Time

A

Delay between peak rainfall and peak discharge

23
Q

Description: Rising Limb

A

The increase in river discharge

24
Q

Description: Falling Limb

A

The decrease in river discharge to normal level