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Storm Surge

  1. Storm Surges Physical Science
  2. 1. Is an unusual localized increase in seawater level, beyond the predicted astronomical tide level, primarily due to intense winds and reduced atmospheric pressure during the passage of an intense cyclone from sea to land. 2. Storm surges are the primary cause of about 90 percent of casualties and damage to properties in coastal areas during a tropical cyclone. 3. The Philippines is highly prone to storm surges because of its location near the equator in the Pacific region and due to the extensive length of its coastline. 4. According to the World Factbook the Philippines has a total coastline length or 36,289 km making it the fourth longest in the world. 5. Tsunami literally means harbor wave in Japanese, strictly speaking this term pertains to a seismic sea wave. What is a Storm Surge?
  3. What is a Storm Surge?
  4. Difference between a Tsunami and Storm Surge ● Can reach heights of more that 10 meters ● Has longer wavelength ● Are formed when a volume of water ● Arrival of tsunamis typically range from minutes to hours ● Can only reach tens to hundreds of meters ● Normal sea waves reach several centimeters to a few meters ● The wavelength of a tidal wave can so wide that it may take as much as 24 hours to arrive Tsunami Storm Surge
  5. Factors that influence The Build-up of Water Level during a Storm Surge 01
  6. During a tropical cyclone storm surge level is also influenced by atmospheric pressure. A lower atmospheric pressure results in a higher storm surge level. Lowered atmospheric level and wind speed are the major causes of storm surge formation. 1. Storm Intensity A storm surge is mainly wind driven storm intensity which is related to the wind speed of a storm, influences the amount of surge produced. 2. Pressure Effect 3. Size A tropical cyclone with a larger diameter will form a higher surge because the wind brought about by larger tropical cyclones push on a larger surface area of the ocean and affects this area for longer period of time.
  7. The amount if surge formed is affected by the angle by which the tropical cyclone hits the coastline. 4. Storm Forward Speed A tropical cyclone travelling with a higher velocity will produce a higher surge along an open coast. A slow moving tropical cyclone also causes more destruction because a greater amount of rainfall is dumped over the area which causes more flooding inland. 5. Angle of Approach to coast 6. Effects of the Earth’s Rotation There is a tendency for ocean currents to be deflected as a result of the earth's rotation. This is called the Coriolis effect.
  8. 7. Rainfall Effect Water levels can rise quickly in estuaries because large volumes of accumulated rainwater from watersheds in higher elevation areas, which are drained by rivers, encounter waters driven by the tropical cyclone from the open ocean.
  9. 8. Geometry of Coastal Area Shape of coastline Storm surge level is higher when a tropical cyclone hits a concave coastline. Bathymetry the appearance of the ocean or sea bottom resulting from the variation in depth with different portions. Local Features Local features found within the coastal area may affect the flow of water and the behavior of the storm surge. Topography Wide low lying areas with elevation of only a few meters above sea level are vulnerable to storm surges.
  10. 9. Timing As with the occurrence of a lot of other natural phenomena, timing plays as an important role. When the formation of a storm surge during a tropical cyclone coincides with high astronomical tide resulting the surge is higher.
  11. Storm Surge Risk Reduction Measures Storm Surge Prediction, Hazard Map Preparation and Zoning Construction of Storm Surge barriers Wetland Protection
  12. 1. Check your house and land for any potential dangers related to flooding. Identify any vulnerability and repair it. 2. Sandbags are a valuable tool to prevent water from entering your home. This approach requires specific instructions from your local emergency officials. 3. Learn how to turn off the gas and electricity in your house. You may be instructed by local authorities to shut these off. 4. If you live in an area that is subject to flooding, do not store your important documents in the basement. Keep them at a higher level, protected from flood damage. 5. Ensure that your family has an emergency kit and plan. 6. Ensure your emergency kit is portable, in a back-pack or suitcase with wheels. Preparing for a Storm Surge
  13. 1. Check supplies including medications, radio, flashlight and batteries. 2. You may have to evacuate. Keep your emergency kit close at hand. 3. Make sure the basement windows are closed. 4. Fuel your car. If evacuation becomes necessary, it will be hard to stop for gas. If a Storm Surge is forecast
  14. 1. Stay inside where you are protected from the water. It's best to be on the downwind side of the house, away from windows. 2. Monitor the storm's progress and listen for warnings or instructions from local officials. 3. Before driving anywhere, listen carefully to rescue officials who will be coordinating evacuation plans. 4. Do not drive through flood waters. 5. Be aware of risks such as hypothermia from cold water or drowning from running water. During a Storm Surge
  15. 16,000,000 People Affected
  16. 3,400,000 Families Affected
  17. Houses Transmission towers and Electric cooperatives 33 Million Coconut trees 248 and 33 More than 1 MIllion 600,00 Hectares of agricultural land Damaged or Destroyed
  18. 1,200+ Provincial, city, municipal and district halls 305 KM Farm to Market Road 20,000 Classrooms 400+ Health Facilities