Disaster Risk Reduction: Hydrometeorological Hazards in the Philippines

Understanding Hydrometeorological Hazards

  • Definition: Natural processes or phenomena of atmospheric, hydrological, or oceanographic origin.

  • Potential impacts:

    • Loss of human lives

    • Damage to property

    • Disruption of economic and social activities

    • Environmental destruction

ITCZ and Weather in the Philippines

  • The Philippines is affected by the Intertropical Convergence Zone (ITCZ).

  • ITCZ brings warm and humid air year-round due to its proximity to the sun.

Effects of ITCZ

  • Results in:

    • Frequent formation of convective clouds

    • Heavy precipitation (rainfall)

    • Prolonged wet season compared to dry season

  • Explanation for increased frequency of hydrometeorological hazards in the Philippines.

Major Hydrometeorological Hazards

  1. Typhoons (Tropical Cyclones)

    • Defined as large, organized storm systems with strong winds and heavy rain.

    • Known as hurricanes or cyclones in different regions of the world.

  • Classification in the Philippines (PAGASA):

    • Tropical Depression: Wind speeds up to 61 km/h61 km/h

    • Tropical Storm: Wind speeds of 6262 to 88 km/h88 km/h

    • Severe Tropical Storm: Wind speeds of 8989 to 117 km/h117 km/h

    • Typhoon: Wind speeds of 118118 to 184 km/h184 km/h

    • Super Typhoon: Wind speeds exceeding 185 km/h185 km/h

  1. Floods and Flash Floods

    • Flooding: The overflowing of water onto normally dry land, often caused by heavy rainfall or overflowing rivers.

    • Flash Floods: Rapid-onset floods characterized by high-volume water flow in a short period, typically occurring in low-lying areas or narrow valleys.

  2. Storm Surge

    • An abnormal rise in sea level caused by the low pressure and strong winds of a tropical cyclone.

    • Can cause massive coastal flooding and is often the most lethal aspect of a typhoon.

  3. El Niño and La Niña (ENSO Cycle)

    • El Niño: A climate pattern representing the unusual warming of surface waters in the eastern tropical Pacific Ocean, leading to drought and reduced rainfall in the Philippines.

    • La Niña: The counterpart to El Niño, characterized by unusually cold ocean temperatures, often resulting in increased rainfall and higher typhoon frequency.

  4. Rain-Induced Landslides

    • Downward movement of soil, rocks, and debris triggered by heavy or prolonged rainfall saturating the ground.