Hydrometeorological Hazards

• Hydrometeorological hazards - are dangers associated

  with the natural processes or phenomena involved in

  the transfer of water and energy between the land

  surface and the lower atmosphere.
• Typhoons, or bagvo in Filipino, are intense circulating winds with heavy rain over tropical waters and land. Typhoons are

  actually tropical cyclones whose winds have reached more than 118 kilometers per hour, which is why it is described as

  ïntense"
• • Tropical depression (TD): up to 61 kph
  • Tropical storm (TS): 62 to 88 kph
  • Severe tropical storm (STS): 89 to 117 kph Typhoon (TY): 118 to 220 kph
  • Super typhoon (STY): exceeding 220 kph
• Thunderstorm - also known as electrical storm, is a storm characterized by

  heavy rain with the presence of thunder and lightning. Thunderstorms may not

  have strong winds in contrast with typhoons.
• Flood - is the presence of excessive water on a supposedly dry

  land. It can be caused by continuous heavy rain or poor

  drainage.
• Flash flood - is a rapid flow of water on saturated soil or dry soil or

  any foundation that has poor absorption capability.
• Storm surge - is an abnormal rise in coastal waters due to a massive force

  from the sea or from the air above the sea. Storm surges can be caused by

  a strong typhoon or a sea quake.
• Tornado - is a rapidly rotating column of air that is in contact with the

  air and land. Its rotational movement is so violent that it can pick up

  objects from the ground and sling them away at far places.
• El Niño and La Niña are both natural parts of the global

  climate systems. These events occur in the Pacific Ocean

  when the waters and the atmosphere above it deviate from

  their normal temperatures.
• El Niño - is usually associated

  with the warming of the central and tropical waters of the

  Pacific Ocean.
• La Niña - would have the exact

  opposite which is the cooling of the same areas in a

  different season.
• El Niño - phenomenon refers to the large-scale warming of the ocean and atmosphere across the central and east-

  central Equatorial Pacific.
• La Niña - begins in the eastern part of the Pacific Ocean, much similar to the location of El Niño.
• Hydrological map - is a chart showing such hydrologic features as rivers and streams.
• This map is divided and subdivided into successively smaller hydrologic units which are classified into four levels:

  regions, sub-regions, accounting units, and cataloging units.
• The first level of classification divides the Nation into 21 major geographic areas, or regions. These geographic areas

  contain either the drainage area of a major river, or the combined drainage areas of a series of rivers which includes a

  number of rivers.
• The second level of classification divides the 21 regions into 221 sub-regions. A sub region includes the area drained by a

  river system, a reach of a river and its tributaries in that reach, a closed basin(s), or a group of streams forming a coastal

  drainage area.
• The third level of classification subdivides many of the sub-regions into accounting units. These 378 hydrologic

  accounting units are nested within, or can be equivalent to the sub-regions.
• The fourth level of classification is the cataloging unit, the smallest element in the hierarchy of hydrologic units. A

  cataloging unit is a geographic area representing part of all of a surface drainage basin, a combination of drainage basins,

  or a distinct hydrologic feature. These units subdivide the subregions and accounting units into smaller areas. There are

  2264 Cataloging Units in the Nation. Cataloging Units sometimes are called "watersheds."
• Doppler radar – used to measure important weather parameters such as amount of rainfall and direction, speed, and

  intensity of winds. These data are used to forecast weather conditions and upcoming typhoon weeks before the

  occurrence.
• Automated rain gauge – usually installed in telecommunication cell sites to observe and locate areas with excessive

  amount of rainfall. This is used to detect for possible flooding and flash floods.
• The geographic location of the Philippines does not only

  pose geological threats but also hydrometeorological

  hazards. The Philippines is in the Northern Hemisphere,

  which is above the equator. The area near the equator,

  known as the Intertropical Convergence Zone (ITCZ), is

  where trade winds meet. Trade winds flow in opposite

  directions and this is the reason that strong swirling of

  wind happens.
• Thunderstorms usually happen in summer because of the atmosphere's high

  humidity and high temperature. The lightning comes from the separation of

  charged particles in the clouds.