DRRR

• Landslide


  Ground movement on a sloping terrain

  
• Landslides do not happen on flat ground because of the angle on the ground, gravity induces the land to move downward

  
• Landslides are aggravated by rain because water is a natural agent for erosion
• If rain or any source of water frequently flows down a sloping area, the gravitational descent of loosened soil makes it possible for landslide to occur

  
• Structures built on steep-slope mountains

  • Have a high vulnerability to landslide hazards especially during heavy rains

  
• Areas with steep slope, dense population and denuded terrain

  • Are distinguished by a high susceptibility to rainfall-induced landslide hazards

  
• Long or regular rain may saturate the topsoil and the bedrock, weakening the soil base of buildings or structures
• Without plants and trees whose roots can absorb water and hold the soil together, subsequent rain water can continue to loosen up the soil that anchors the buildings
• A heavy downpour of rain can quickly destroy these buildings and communities, giving way to landslides, mudslides, or mudflows
• Soil Creep


  Slow downslope movement of particles that occurs in every slope covered with loose, weathered material
• Slumping


  Downward movement of rock debris, usually the consequence of removal of buttressing earth at the foot of a slope of unconsolidated material
• Debris Flow


  Landslide happens when the slope becomes saturated with water, this then triggers a landslide of water-soaked mass of rock and soil that slides down the slope

  
• Rock Fall


  Sudden slides caused by heavy rain the rock on the slope loosens and then slides down the slope
• Sinkhole


  Topographic depression created when groundwater dissolves the underlying limestone bedrock
• Sinkholes occur in areas where the soil foundation is made of soft minerals and rocks such as limestone, salt beds, or any acidic rocks
• The depth of sinkholes ranges from a couple of meters to several miles deep
• How sinkholes occur

  1. Water from the rainfall seeps underneath the soil through the cracks and fissures

  2. As water passes through these cracks and fissures, it erodes the soil and forms a conduit system

  3. These underground water systems increase in size as the soil is carried by the water through internal erosion

  4. This can either form a void filled with air with an underground drainage

  5. If the void is clogged with clay, then it forms a depression which then accumulates water and forms a pond

  6. Otherwise it forms a hole once the cover collapses into the void which can be either filled with air or water
• Types of sinkholes

  • Cover Collapse Sinkhole
  • Cover Subsidence Sinkhole
  • Dissolution Sinkhole
  • Artificial Sinkhole
• Cover Collapse Sinkhole


  Develops suddenly (over an hour period) thus, causing catastrophic damage
• Cover Subsidence Sinkhole


  Gradually grows where the sediment covers are permeable and contain sand
• Dissolution Sinkhole


  Occurs in areas where calcareous is exposed on the ground or where thin layers of soil and permeable sand are also covered. Limestone or dolomite dissolution is most intense when the water first reaches the rock surface
• Artificial Sinkhole


  Such types of sinks may be caused by various human activities, including groundwater pumping and building
• The Philippines being located in the Southeast Asia is considered very vulnerable to natural hazards and disasters, which include typhoons, earthquakes, floods, volcanic eruptions, landslides, and fires that affect the country and its inhabitants

  
• Surrounding the Pacific Ocean basin is a circular arm of active volcanoes known as the "Pacific Ring of Fire" in which most of the volcanoes in the Philippines are part of
• Continental plate activities around this area result to volcanic eruptions and tsunamis in the country
• Hydrometeorological hazards


  Processes or phenomena of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage
• Hydrometeorological hazards

  • Typhoon
  • Thunderstorm
  • Flood
  • Flashflood
  • Storm Surge
  • El Niño
  • La Niña

  
• Hydrometeorological conditions lead to other hazards such as landslides, fires, plagues, epidemics and in transport and dispersal of toxic substances and volcanic eruption material
• Tropical cyclone


  Intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain
• PAGASA stated that weather forecast is a scientific estimate of future weather condition, wherein a weather condition is a state of the atmosphere at a given time expressed in terms of the most significant variables
• How a weather forecast is made

  1. Observation

  2. Collection and Transmission of Weather Data

  3. Plotting of Weather Data

  4. Analysis of Weather Maps, Satellite and Radar Imageries and Other Data

  5. Formulation of the Forecast
• Thunderstorm


  Powerful, short-lived weather disturbance, almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds

  
• Stages of thunderstorm formation

  1. Cumulus Stage

  2. Mature Stage

  3. Dissipating Stage

  
• Flood


  High-water stage in which water overflows its natural or artificial banks onto normally dry land, such as a river inundating its floodplain
• Types of floods

  • Inland flooding
  • Flash floods
  • River flooding
  • Coastal flooding
  • Urban flooding
• Storm surge


  Irregular sea-level rise during tropical cyclone where powerful winds force the ocean water over the coastal low-lying areas, which can lead to flooding

  
• PAGASA takes many technological considerations into account when forecasting the negative impacts of a storm surge

  
• El Niño


  Large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific
• La Niña


  Periods of below-average sea surface temperatures across the east-central Equatorial Pacific
• El Niño and La Niña are opposite results of ENSO (El Niño Southern Oscillation), the same phenomenon