Rivers & Environments

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Rivers & Environments

  1. 1. Rivers & Environments <ul><li>Earth’s water </li></ul><ul><li>Hydrological Cycle </li></ul><ul><li>River System </li></ul><ul><li>Drainage Basin </li></ul><ul><li>Features from Rivers </li></ul>
  2. 2. Earth’s Water <ul><li>About 75% of the Earth’s surface is covered with Water. </li></ul><ul><li>97% of Earth’s Water is Salt water, contained in seas and oceans. </li></ul><ul><li>But ONLY 3% of the Water is Fresh Water. </li></ul><ul><li>Out of the 3% of fresh water, ONLY 1% is stored on streams, lakes and rivers . </li></ul>
  3. 3. Earth’s water 75% of Earth is Water 97% is saltwater 3% is freshwater 99% stored in glacier, Ice-sheet or underground Only 1 % is Found in streams Lakes/ rivers
  4. 4. Singapore’s Water
  5. 5. What about Singapore? <ul><li>As a small island that doesn't have natural aquifers and lakes and with little land to collect rainwater, Singapore needs to maximise whatever water it can harvest. </li></ul><ul><li>Thus, it is important to clean up Singapore River or any other drainage channels. </li></ul><ul><li>A pervasive network of drains, canals and rivers channels rain water to Singapore’s 14 reservoirs. </li></ul><ul><li>When the Marina Barrage is completed, it will give birth to the nation’s 15th reservoir and the first in the city. </li></ul><ul><li>. </li></ul>
  6. 6. Recap: QUIZ <ul><li>How much of the Earth’s surface is made up of Water? </li></ul><ul><li>Ans: 97% </li></ul><ul><li>How much of the Earth’s available water is fresh water? </li></ul><ul><li>Ans: 3% </li></ul><ul><li>Where are 1% of Earth’s fresh water found? </li></ul><ul><li>Ans: Streams, Lakes, Rivers </li></ul>
  7. 7. Water Cycle
  8. 8. <ul><li>The earth first gain water by precipitation, such as rainfall. </li></ul><ul><li>The water from the rainfall can end up in sea/oceans or on land as surface runoff. </li></ul><ul><li>Most of water will end up in sea/oceans, while some would end up on earth surface. </li></ul><ul><li>Eventually the water on land would end up in oceans/seas as surface runoff. </li></ul>
  9. 9. Hydrologic cycle - continuous movement of water, moving from Earth’s surface into the air and from air back to earth’s surface
  10. 10. Recap:
  11. 11. River System <ul><li>River is a body of water in a channel. </li></ul><ul><li>Structure of a river: </li></ul>Tributaries
  12. 12. Drainage basin
  13. 13. Recap: Source Tributary Mouth Watershed Confluence
  14. 14. Do rivers simply flow through the whole course? <ul><li>NO! Rivers ‘DO WORK’ along the way from the source to the mouth. </li></ul><ul><li>At upper course , usually erosion takes place. </li></ul><ul><li>By erosion, we mean that there is high energy level, river ‘remove’ / ‘take’ materials along with the flow. </li></ul>
  15. 15. Rivers doing work <ul><li>At the middle course, there is lesser energy as compared to upper course. </li></ul><ul><li>Imagine you are on a slide, at the beginning, it is very fast, but at the middle of it, you start to slow down. </li></ul><ul><li>But, still, certain level of erosion can take place. </li></ul><ul><li>But more of transportation would take place. </li></ul><ul><li>Feature like meanders may be formed. </li></ul>
  16. 16. At the lower course <ul><li>All good things come an end. At the end of the slide ride, all things come to standstill, meaning, no or very low energy. </li></ul><ul><li>Usually, erosion would not take place. </li></ul><ul><li>Instead, deposition takes place. </li></ul><ul><li>Materials that are carried by the river is deposited at the lower course. </li></ul><ul><li>Features like floodplain, deltas are formed. </li></ul>
  17. 17. Features formed from river <ul><li>Extensive overview of features that can be found along a river course </li></ul>
  18. 18. At different course.
  19. 19. 1. Valley <ul><li>Valley is a low area between hills or mountains. </li></ul>
  20. 20. 2. Water fall <ul><li>Waterfall is a vertical flow of fast-moving water falling from great height. </li></ul>
  21. 21. 3. Meanders <ul><li>Meanders are curves and bends formed when river erodes sideways and deposits the sediments it is carrying on opposite banks. </li></ul>
  22. 22. 4. Floodplains <ul><li>Floodplain is low-lying land that becomes flooded when a river overflows. </li></ul>
  23. 23. 5.Delta <ul><li>Delta is formed when layers of sediments are deposited at the river mouth over time. </li></ul>
  24. 24. Rivers and People <ul><li>Benefits </li></ul><ul><li>Water supply for farming/ Industry </li></ul><ul><li>Water for consumption </li></ul><ul><li>Recreation/ tourism </li></ul><ul><li>Production of hydroelectric energy </li></ul><ul><li>Means of transport </li></ul><ul><li>Risks/ Problems </li></ul><ul><li>Flooding </li></ul>

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