Hydrometeorological Hazards and Disasters

Storm Surge

• PAGASA-DOST defines storm surge as a sudden sea level rise during a tropical cyclone due to:

  • Drop in atmospheric pressure.

  • Force of the wind.

• Factors influencing surge height:

  • Tropical cyclone strength.

  • Coastline depth.

• Peak surge: Near typhoon landfall.

• Impact: Flooding and damage in low-lying areas, especially during high tide.

• Causes:

  • Wind/pressure effect: Stronger wind, lower pressure = higher surge.

  • Rainfall effect: Heavy rains increase sea level.

  • Tidal effect: High tide amplifies surge.

  • Coastline shape/seabed slope: Shallower slope = higher surge.

• Preparedness:

  • Disaster preparedness plans with evacuation procedures.

  • Danger zone identification.

  • Land-use regulations.

  • Safety structures (seawalls, dikes, etc.).

  • Mangrove planting.

  • Efficient transport, rescue, and relief systems.

• Individual/family actions: Evacuation plans to higher ground.

Thunderstorm Preparedness

• PAGASA-DOST guidelines:

  • Go indoors.

  • Avoid conducting electricity.

  • Don't use plug-in appliances or phones.

  • Stay in your car if driving.

  • Avoid metal objects and water.

  • Seek lightning shelter.

  • If no shelter, avoid tall, solitary objects.

  • Squat low to the ground if caught outside.

  • If you feel an electrical charge, drop to the ground.

Tornado

• Localized windstorm with a visible funnel cloud.

• Also known as twister, buhawi, or ipo-ipo.

• Acts like a vacuum cleaner, lifting objects.

• Wind speeds can exceed 450 kph.

• Waterspout: Tornado over water.

• Precursory signs:

  • Funnel-shaped column from cumulonimbus cloud.

  • Warm, humid, calm weather.

  • Lightning and thunder.

  • Roaring/buzzing sound.

Flooding

• PAGASA's color-coded warning signals:

  • Red: > 30 mm rain - Evacuate.

  • Orange: 15-30 mm rain - Prepare for evacuation.

  • Yellow: 7.5-15 mm rain - Monitor.

• Before flooding:

  • Know flood risk and warning systems.

  • Stay informed on weather.

  • Designate evacuation areas.

  • Stock food, radio, flashlight, first-aid kit.

  • Secure dwellings.

• When warned:

  • Be alert during prolonged rain.

  • Listen to the radio for instructions.

• During flooding:

  • Avoid flooded areas.

  • Don't cross deep water.

  • Beware of hazards.

  • Cook food well; use clean water.

• After flooding:

  • Enter cautiously with light.

  • Beware of fire hazards.

  • Check water/food for contamination.

  • Report utility damage.

  • Get electrical equipment checked.

  • Consult health authorities.

  • Avoid sightseeing.

Public Storm Warning Signals

• Signal #1: Winds of 30-60 kph expected in 36 hours. Listen to the radio, check house capacity, continue business as usual.

• Signal #2: Winds of 61-120 kph expected in 24 hours. Secure properties, board up windows, listen to the news, stay at home.

• Signal #3: Winds of 121-170 kph expected in 18 hours. Stay indoors, evacuate low-lying areas, watch for the eye of the typhoon.

• Signal #4: Winds of 171-220 kph expected in 12 hours. Stay in safe shelter, cancel travel, expect heavy damage.

• Signal #5: Winds >220 kph expected in 12 hours. Stay in safe shelter, cancel travel, expect extreme damage.

Tropical Cyclones

• Tropical cyclone: intense low pressure system, minimum sustained wind velocity of 35 kph.

• Eye: 10-100 km diameter, light wind and no rain.

• Eye wall: Heaviest precipitation and strongest wind.

• Secondary hazards: floods, storm surges, strong winds, landslides, and mudflows.

El Ni

• El Ni or La Ni : Natural climate system variations; part of ENSO.

• El Ni: Warming.

• La Ni: Cooling.

Climate Change

• Climate change: A shift in climate properties (temperature, wind, precipitation) over decades or longer due to natural or human causes.

• Global warming: Increase of GHGs, affects the environment and communities.

• Mitigation: Reduce GHG emissions or increase carbon storage.

• Adaptation: Adjust to climate change by reducing vulnerability, moderating damages, and realizing opportunities.

• Low carbon diet includes: compact fluorescent lamps, 3Rs (reuse, reduce, recycle), energy-efficient appliances, walk/bike/carpool, mass transportation, turning off lights and appliances when not in use.

Global Warming and Climate Change effects observed in the Philippines

• Super typhoon Yolanda (Haiyan) as one of the strongest recorded typhoons ever

• Some provinces in Mindanao and Western Visayas that used to be free from typhoons have now become paths of the said hazard.

• Observed an increased mean temperature of 0.65 °C during the period from 1951 to 2010

How to prepare for drought

• Build structures that can conserve water such as dams, dikes, and irrigation systems.

• Issue an early warning to prepare the people, communities, and institutions.

• Conserve water even prior to the occurrence of the drought.

• Adopt indigenous practices in agriculture which could vary depending on the physical situations and cultures in communities.

• Preserve and store food.

• Desalinate water supply.

• Change lifestyle to adapt to drought.