Case Studies

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Key vocab:

• Drainage basin: area of land drained by a river and its tributaries
• Watershed: an imaginary line that separates one drainage basin from another
• Interception: how precipitation is prevented from reaching the ground like trees
• Overland flow/surface runoff: when water cannot infiltrate the soil due to it being impermeable
• Throughflow: water flows through the soil
• Groundwater flow: water flows through the rocks
• Source: point where the river begins
• Mouth: point where a river meets the sea
• Confluence: place where two or more rivers meet
• Tributaries: streams flowing into larger rivers </aside>

hydrological cycle:

The hydrological cycle involves the continuous circulation of water in the Earth-Atmosphere system

• Stores: places where water is kept for a period of time
  • Clouds
  • Soil moisture
  • Lakes
• Flows: how water is moved around the hydrological cycle
  • Precipitation
  • Overland flow
  • Percolation
• The hydrological cycle is a closed system and has no inputs or outputs
• A drainage basin is an open system and has both inputs and outputs

• No of tributaries = drainage density
  • Lot of tributaries = high drainage density
  • Few tributaries = low drainage density
• Where the rock or soil is impermeable, there is high drainage density because the water cannot infiltrate and flows over the surface

rivers:

Long Profile:

• Shows the changes in a river gradient from its source to mouth
• Usually a concave shape (curved inwards)
• Upper course: steep with uneven edges
• Middle course: gradient decreases
• Lower course: almost flat

Cross profile:

• Cross sections from one bank to another

Upper course:

• Vertical erosion

• Shallow channel

• Steep valley side

• Narrow channel

• Low velocity due to obstacles like rocks

• Rough channel bed

  • High levels of friction

  

Middle course:

• Lateral erosion
• Deeper and wider
• Gentle valley sides
• Greater velocity
• Smoother channel bed

  • Lower levels of friction

    

Lower course:

• Deepest channel

• Flat floodplains

• Wider channels

• Greatest velocity

  • Lowest friction

• Smooth channel bed

  

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• The discharge and velocity increase down the course because
  • More water joins the river through tributaries
  • River gets wider and deeper allowing water to move smoothly and quickly
  • There are less obstacles so water can move freely
  • The energy is used more efficiently
    • In the upper course, energy is lost by overcoming obstacles
    • In the lower course, energy is used to increase speed </aside>

river processes:

There are three types of river processes: erosion, transportation and deposition

There are 4 types of erosion:

Factors affecting rate of erosion: