Full Geography Secondary 3 Express- Floods and Droughts 2


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Full Geography Secondary 3 Express- Floods and Droughts 2

  1. 1. + 3 Express Pure Geog: Floods and Droughts 19h April 2012 Causes of Floods and Droughts Arman Alluwie TP2 SHSS
  2. 2. + 2 Lesson Objectives  By the end of the lesson, we would have  discussed the impact of floods and droughts on human lives and the environments  evaluate the effectiveness of management strategies taken to mitigate and respond to floods and droughtsArman Alluwie TP2 SHSS
  3. 3. + 3 Lesson Recap: Floods and Droughts  Hazard  Definition: can endanger lives and destroy property  Flood  Definition: occurs when land that is usually dry is submerged by large amounts of water  Drought  Definition: prolonged period with little or no rainfall  normally occurs in regions which receive 250- 500 mm per yearArman Alluwie TP2 SHSS
  4. 4. + 4 Lesson Recap: Causes of Floods  Natural Causes 1. Excessive rainfall 2. Storm surges 3. Melting snow 4. Global atmospheric processes 5. Movements of the Earth’s surface  Human Causes 1. Clearing of forests 2. Urban development 3. Impacts of enhanced greenhouse effectArman Alluwie TP2 SHSS
  5. 5. + 5 Causes of Droughts  Natural causes of droughts 1. Delayed rain or insufficient rainfal 2. Global atmospheric processes  Human causes of droughts 1. Reduced forest cover 2. Impact of enhanced greenhouse effect 3. Overuse of waterArman Alluwie TP2 SHSS
  6. 6. + 6 Lesson Recap: Storm surges http://www.nhc.noaa.gov/surge/animations/hurricane_stormsurge.swfArman Alluwie TP2 SHSS
  7. 7. + 7 Droughts Heavy RainsIndonesia/ Peru,Australia South America Arman Alluwie TP2 SHSS
  8. 8. + 8 Heavy Rain DroughtsIndonesia/ Peru,Australia South America Arman Alluwie TP2 SHSS
  9. 9. + 9 Human causes of floods: Clearing of forests TitleArman Alluwie TP2 SHSS Legend
  10. 10. + 10 Feedback  Reducing Impact of Climate Change  Pg 125  Not important  Answers to Worksheet 8.1  Student HandoutArman Alluwie TP2 SHSS
  11. 11. + 11 Natural Hazards Floods Droughts Causes Natural causes Natural causes Eg. Excessive rainfall Eg. Delayed or insufficient rainfall Human causes Human causes Eg. Clearing of forests Eg. Reduced forest cover Impact on people and Eg. Loss of lives Eg. Shortage of water the environment and food How people have Eg. Building artificial Eg. Management of adapted to floods and levees or dykes watershd and droughts agricultural practices Today pg. 138- 147 of textbookArman Alluwie TP2 SHSS
  12. 12. + 12 Impacts of Floods: Fertile Soil / Loss of Lives  Provides fertile alluvium  Floodplains around coastal areas and rivers  attractive places for cultivation of crops/ farming  many people continue to live on low-lying plains near rivers despite risk of floods positive impact  BUT when flooding occurs, lots of lives are lost  Based on location and predictability  Eg. 2003, north-central Huai River Basin  298 lives negative impactArman Alluwie TP2 SHSS
  13. 13. + 13 Impacts of Floods: Damage to Property and Infrastructure  Disrupts power supply and phone lines, cutting off communication  Making relief efforts and emergency evacuations difficultArman Alluwie TP2 SHSS
  14. 14. + 14 Impacts of Floods: Spread of diseases  Overcrowded makeshift shelters  Lack of sanitation and clean drinking water  Especially in countries where sewage is not piped  Floating debris / Dead bodiesArman Alluwie TP2 SHSS
  15. 15. + 15Arman Alluwie TP2 SHSS
  16. 16. + 16 Impacts of Floods: Damage to Environment  Destroys plant life and natural habitats of animals  eg. Tsunami that struck Java on 17 July 2006  severe damage to the coastal ecology  nature reserve near Pangandaran BeachArman Alluwie TP2 SHSS
  17. 17. + 17 Impact of Droughts: Shortage of Water and Food  People and animals die from dehydration and crops destroyed  Especially crops which are dependent on seasonal cycles  eg. monsoon rain  Leads to famineArman Alluwie TP2 SHSS
  18. 18. + 18 Impact of Droughts: Forest fires and haze  Vegetation becomes very dry and catches fire easily  Note that a drought is defined as “prolonged period with little or no rainfall”  An area may be experiencing drought but still have vegetation around.  Smoke from forest fires lead to haze in neighboring countries  Affects environment and health of peopleArman Alluwie TP2 SHSS
  19. 19. + 19 Impacts of Droughts: Damage to the environment  Desertification  spread of deserts into areas where there is little or no rain  Arid and Semi- Arid Regions  places with 250- 500 mm of rainfall per year  Soil becomes very dry and unable to support vegetation  Soil blown away by wind, leaving a barren piece of land  Deserts around the world are expanding at a rate of about 80 000 square kilometres per year. (desertification vulnerability)Arman Alluwie TP2 SHSS
  20. 20. + 20 Checkpoint 1: Impacts of Floods and Droughts Floods Droughts Impact on 1. Loss of lives 1. Shortage of water and people and the 2. Damage to property food environment and infrastructure 2. Damage to the 3. Spread of diseases environment 4. Damage to the 3. Forest fires and haze environment 5. Fertile Soil for agricultuream I able to discuss the impacts of floods and droughts on human lives and theenvironments? pg 138- 142Arman Alluwie TP2 SHSS
  21. 21. + 21 Flood Management Strategies: Building artificial levees/ dykes  walls of sand, stone and concrete  increases holding capacity of river  BUT must be paired with other strategies  Yellow River, China not successful in preventing floods because of constant deposition of sediment  river bed becomes raised, making river shallower  water levels rise higher than the dykes  higher dykes have to be built constantlyArman Alluwie TP2 SHSS
  22. 22. + 22Arman Alluwie TP2 SHSS
  23. 23. + 23 Flood Management Strategies: Construction of Dams  Control the amount of water flowing into rivers  Gates which hold back or release water from the man- made reservoir behind it  reservoir increases holding capacity  Controls the amount of water that flows downstream  BUT slowing down the speed of water  increases the accumulation of sediments  not enough energy to carry sediments  raise reservoir bed and cause flooding in the futureArmanAlluwie TP2 SHSS
  24. 24. + 24 Flood Management Strategies: Construction of Dam  Three Gorges Damn, Yangtze River 2:49- 5:55 of http://www.youtube.com/watch?v=3z9K82ZVdMAArmanAlluwie TP2 SHSS
  25. 25. + 25 Flood Management Strategies: Building Control  providing information for developers in flood prone areas  construction of good network of drainage canals  eg. flood prone areas in Singapore have dropped from 3200 ha in 1970 to 238 ha in 2006Arman Alluwie TP2 SHSS
  26. 26. + 26Arman Alluwie TP2 SHSS
  27. 27. + 27Arman Alluwie TP2 SHSS
  28. 28. + 28 Flood Management Strategies: Watershed Management  Watershed  boundary which is marked by crests of hill rides and mountains  separates on drainage basin from the nextArman Alluwie TP2 SHSS
  29. 29. + 29Arman Alluwie TP2 SHSS
  30. 30. + 30 Flood Management Strategies: Watershed Management  Eg. Royal Forest Department (RFD) in Thailand  detailed plans on conserving natural vegetation in watersheds  re-planting tress in areas which were previously cut down  reducing surface runoff and amount of sedimentsArman Alluwie TP2 SHSS
  31. 31. + 31 Flood Management Strategies: Flood Insurance  Financial resources to rebuild property if a flood strikes  Depending on trends and history of floods  eg. UK, national flood insurance programmme  helps reduce financial burdenArman Alluwie TP2 SHSS
  32. 32. + 32 Flood management strategies: Monitoring and education  modern technology allows us to monitor weather patterns and issue warnings  Educating citizens on what to do in the event of a flood  Evacuation plans  Safest route to the nearest food shelter  Public announcements  Flood warning signsArman Alluwie TP2 SHSS
  33. 33. + 33 Flood Management Strategies: Post-flood management measures  Evacuation plans  boats / helicopter to temporary shelters  Opening public areas for humanitarian and rescue operations  Louis Armstrong New Orleans International Airport during Hurricane Katrina  Foreign Aid in the form of food, water, blankets, medical teamsArman Alluwie TP2 SHSS
  34. 34. + 34 Checkpoint 2: Flood Management Strategies 1. Building Artificial Levees/ Dykes 2. Construction of Dams 3. Building Control 4. Watershed Management 5. Flood Insurance 6. Monitoring and Education 7. Post- Flood Management Measuresam I able to evaluate the effectiveness of management strategies taken tomitigate and respond to floods? pg 142- 145Arman Alluwie TP2 SHSS
  35. 35. + 35 Drought Management Strategies: Management of watershed and agricultural practices  Agenda 21 Report  Eg. Mongolia  hundreds of thousands of seedlings planted to increase vegetation in drought-affected regions  laws to limit the number of trees  only local community allowed to cut down trees for firewoodArman Alluwie TP2 SHSS
  36. 36. + 36 Drought Management Strategies: Management of watershed and agricultural practices  Growing crops to suit the dry climate of regions  Changing staple diet or importing foodArman Alluwie TP2 SHSS
  37. 37. + 37 Drought Management Strategies: Using proper irrigation techniques  brings water to areas which receive little or no rainfall  eg. Turkey, precision sprinklers drip small amounts of water directly onto cropsArman Alluwie TP2 SHSS
  38. 38. + 38 Drought Management Strategies: Cloud Seeding  induces formation of rain  disperse substances like silver iodide or dry ic  enable water droplets/ ice crystals to form more easily  nucleus for water droplets in the air to adhere to  over time clouds form and rain falls  dispersed by aeroplanes or machines on the ground  eg. Thailand, 2005, ease drought by 80%  but cost of seeding very high and no guaranteed successArman Alluwie TP2 SHSS
  39. 39. + 39 Drought management strategies: Post- Drought  U.S. Agency for International Development (USAID)  donations of money, food and water to Ethiopia 2006  Food for Hungry Relief  brought in water in tanker trucks and used “dewatering” pumps to transfer the water into school cisternsArman Alluwie TP2 SHSS
  40. 40. + 40 Checkpoint 2: Flood Management Strategies 1. Management of watershed and agricultural practices 2. Using proper irrigation techniques 3. Cloud seeding 4. Post-drought management measuresam I able to evaluate the effectiveness of management strategies taken tomitigate and respond to droughts? pg 146- 147Arman Alluwie TP2 SHSS