Energy of a river

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Energy of a river

  1. 1. Energy of a River
  2. 2. How is the energy of a river determined? <ul><li>Speed of a river </li></ul><ul><li>Volume of a water </li></ul>Energy Low Speed and Volume (Low) Energy High Speed and Volume (High)
  3. 3. What will the amount of energy in a river determine? <ul><li>Erode </li></ul><ul><li>Transport </li></ul><ul><li>Deposit Materials </li></ul>
  4. 4. Why does the energy of a river change? <ul><li>Gradient </li></ul><ul><li>Roughness </li></ul><ul><li>Wetted Perimeter </li></ul><ul><li>Size of drainage basin </li></ul><ul><li>Presence of vegetation </li></ul><ul><li>Permeability of rocks </li></ul><ul><li>Climate </li></ul>Upper Course Middle Course Lower Course
  5. 5. Factors that affect the speed of a river <ul><li>Gradient </li></ul><ul><li>Roughness </li></ul><ul><li>Wetted Perimeter </li></ul>
  6. 6. Gradient of Channel <ul><li>The Steeper the gradient is, the faster is the flow. </li></ul><ul><li>Water flowing down a steep slope has higher velocity than one which flows down a gentler gradient . </li></ul>
  7. 7. Gradient of Channel (Steep) (Gentle)
  8. 8. Roughness of Channel Rocks Boulders Underwater Vegetation River Bed Cause friction between the water and channel, the water has to overcome the friction and this lead to slow down of river flow and reduce of speed .
  9. 9. Roughness of Channel (Lesser Friction) (Higher Friction) Faster River Flow Slower River Flow
  10. 10. Wetted Perimeter <ul><li>Refers to the extent to which water is in contact with its channel. </li></ul><ul><li>The Larger the wetted perimeter is, the river will have to overcome more friction and is slowed down. </li></ul>
  11. 11. Wetted Perimeter Wetted perimeter is calculating by adding the length and the breadth of the channel in contact with water.
  12. 12. Factors that affect the volume of water in a river <ul><li>Size of drainage basin </li></ul><ul><li>Presence of vegetation </li></ul><ul><li>Permeability of rocks </li></ul><ul><li>Climate </li></ul>
  13. 13. Size of drainage basin <ul><li>The larger the drainage basin </li></ul><ul><li>= the more tributaries there are </li></ul><ul><li>= the greater the volume of water </li></ul>Resulting in a * higher surface runoff . * Runoff that moves over the soil surface to the nearest surface stream.
  14. 14. Size of drainage basin Lower surface runoff Lower Volume of water Lesser tributaries Smaller Drainage Basin B Higher surface runoff Greater Volume of water More tributaries Larger Drainage Basin A
  15. 15. Presence of vegetation <ul><li>Intercepts the rain and enables the rain water to infiltrate into the ground. </li></ul><ul><li>Reduces surface run-off and so less water flows immediately into the river. </li></ul>
  16. 16. Presence of vegetation High surface runoff Low surface runoff Low Infiltration High Infiltration Low Interception High Interception Rain Rain
  17. 17. Permeability of rocks <ul><li>Determined by the size of the pores between the rock particles. </li></ul><ul><li>Rock has small pores, water cannot easily infiltrate into the rock </li></ul><ul><li>Rock is impermeable </li></ul>
  18. 18. Permeability of rocks <ul><li>When water flows through an area of impermeable rock </li></ul><ul><li>Little water infiltrates the ground </li></ul><ul><li>High surface runoff and leads to a high volume of flow of water. </li></ul>
  19. 19. Climate <ul><li>Precipitation </li></ul><ul><li>Temperature </li></ul>
  20. 20. Climate Precipitation Temperature High Volume of flow Low volume of flow Low precipitation High precipitation High Rainfall Low Rainfall Wet Season Dry Season Higher amount of water Lower amount of water Lesser evaporation and transpiration More evaporation and transpiration Low Temperature High Temperature
  21. 21. Climate Low rainfall, lower volume of water High rainfall, higher volume of water
  22. 22. Thank You

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