This document discusses various hydrometeorological hazards such as tropical cyclones, thunderstorms, floods, droughts, and more. It provides definitions and descriptions of different types of hazards like tropical cyclones, typhoons, hurricanes, thunderstorms, tornadoes, flash floods, floods, storm surges, El Niño and La Niña. The document also discusses how different hazards are monitored and forecasted using tools like satellites, Doppler radar, and preparedness and mitigation strategies to adopt before, during, and after hazards occur.

2. • Hydrometeorological hazards are
processes or phenomena of atmospheric,
hydrological or oceanographic nature
• may cause loss of life, injury or other
health impacts, property damages, loss of
livelihoods and services, social and
economic disruptions, or even
environmental damages
Hydrometeorological Hazards...

3. Hydrometeorological hazards include:
-TROPICAL CYCLONES (TYPHOONS/HURRICANES)
-THUNDERSTORMS
-HAILSTORMS -DROUGHT
-TORNADOES -HEAT WAVES
-COLD SPELLS -STORM SURGES
-HEAVY SNOWFALL -AVALANCHES
-FLOODS/FLASH FLOODS -BLIZZARDS
Hydrometeorological hazards...

4. Hydrometeorological conditions also can
be a factor in other hazards such as
landslides, wild fires, locust plagues,
epidemics, and volcanic eruptions.
Hydrometeorological hazards...

5. The following are the most common
Hydrometeorological hazards as defined by
the National Oceanic and Atmospheric
Administration (NOAA):
CYCLONE TORNADO
TYPHOON FLASH FLOOD
FLOOD THUNDERSTORM
STORM SURGE EL NIÑO and LA NIÑA
Potential Hydrometeorological
Hazards

7. A cyclone is an intense low pressure
system which is characterized by strong spiral
winds towards the center, called the “Eye” in a
counter-clockwise flow in the northern
hemisphere. Hazards due to tropical cyclones
are strong winds with heavy rainfall that can
cause widespread flooding/flash floods, storm
surges, landslides and mudflows.

8. Classification of Cyclone:
Tropical Depression – maximum winds from
35 kilometers per hour (kph) to 63 kph
Tropical Storm – maximum winds from 64 kph
to 118 kph
Typhoon – maximum winds exceeding
118 kph

10. A typhoon is a large, powerful and violent
tropical cyclone. It is a low pressure area
rotating counter-clockwise and containing
rising warm air that forms over warm water in
the Western Pacific Ocean. Less powerful
tropical cyclones are called Tropical
Depression and Tropical Storms.

11. A typhoon is called a hurricane in the Atlantic
Ocean, a cyclone in Indian Ocean and wily-
wily in Australia. Typhoons can inflict terrible
damage due to thunderstorms, violent winds,
torrential rain, floods, landslides, large and very
big waves associated with storm surges.

13. A thunderstorm is a weather condition
that produces lightning and thunder, heavy
rainfall from cumulonimbus clouds and possibly
a tornado. It is a violent local disturbance
accompanied by lighting, thunder and heavy
rain and often by strong gust of wind, and
sometimes by hail.

14. The typical thunderstorm caused by
convection occurs when the sun’s warmth has
heated a large body of moist air near the
ground. This air rises and called by expansion.
The cooling condenses the water vapor
present in the air, forming a cumulus cloud.

16. • a tornado is described as a violent rotating
column of air extending from thunderstorm to
the ground
• tornadoes come in many sizes
• are typically in the form of a visible
condensation-funnel which is narrow and
touches the earth
• is often encircled by a cloud of debris

17. • have a wide- range of colors depending on
the environment
• typically, may appear nearly transparent and
invisible until dust and debris are picked up
• develop from severe thunderstorms in warm,
unstable air along and ahead of cold fronts

19. A flash flood is a rapid flooding of
geomorphic low-lying areas like washes, rivers,
dry lakes and basins.
Common causes of flash flood:
 heavy rain with a severe thunderstorm
 tropical storm
 melt water from ice
 snow flowing over ice sheets
or snowfields
 hurricane

20. • flash floods may occur after the collapse of a
natural ice or debris dam, or a human
structure such as man-made dam
• flash Floods are distinguished from regular
floods by a timescale of less than six hours

22. Flood is the inundation of land areas
which are not normally covered by water. A
flood is usually caused by a temporary rise or
the over- flowing of a river, stream, or other
water course, inundating adjacent lands or
flood-plains.

23. • temporary rise of lakes, oceans or reservoirs
and/or other enclosed bodies of water
• heavy and prolonged rainfall associated with
tropical cyclones, monsoons, inter-tropical
convergence zones or active low pressure
areas
• debris jam causes a river or stream to
overflow and flood the surrounding area.

24. Floods are basically HYDROLOGICAL PHENOMENA
caused by storm surges, and tsunami
along coastal areas
Two key elements are rainfall intensity and
duration. Intensity is the rate of rainfall, and
duration is how long the rain lasts.

26. Storm surge is the rise of the seawater
above normal sea level over the coast,
generated by the action of weather elements
such as cyclonic wind and atmospheric
pressure. Sea level is raised and driven towards
the coast. Where the depth is shallow and the
slope of the sea bed is gradual, the natural
flow of water is delayed by the effect of
friction on the sea bed.

27. As more water moves from the sea to the
coast excess water piles up on the shore line.
This pilling up of water makes a large volume
of water which might eventually flow into
hinterland some distance from the coast.
Depending upon the shape of the coastline
and the slope of the sea bed, storm surge can
sweep across large portions of coastal areas.

29. El Niño and La Niña are complex weather
patterns resulting from variations in ocean
temperature in the equatorial pacific. These
two phenomena are opposite phases of what
is known as the El Niño-Southern Oscillation
(ENSO) cycle.

30. The ENSO cycle is a scientific term that
describes the fluctuations in temperature
between the ocean and the atmosphere in
the East-central Equatorial Pacific
(approximately between the International
Date Line and 120 degrees West).

31. La Niña is sometimes referred to as the
cold phase of ENSO and El Niño as the warm
phase of ENSO. These deviations from normal
surface temperatures can have large-scale
impacts not only on ocean processes, but also
on global weather and climate.

32. El Niño and La Niña episodes typically last
nine to 12 months, but some prolonged events
may last years. While their frequency can be
quite irregular, El Niño and La Niña events
occur on average every two to seven years.
Typically, El Niño occurs more frequently than
La Niña.

34. The general sequence of events that
could occur during the development of a
Category 2 typhoon/hurricane (wind speed
96-110 mph) approaching a coastal area:
(Herald Tribune, 2011)

35. 96 hours before landfall:
At first there aren’t any apparent signs
of storm. The barometer is steady, winds are
light and variable, and fair-weather
cumulus clouds appear.

36. 72 hours before landfall:
Little has changed, except that the
swell on the ocean surface has increased
to about six feet and the waves come in
every nine seconds. This means that the
storm, far over the horizon, is approaching.

37. 48 hours before landfall:
The sky is now clear of clouds, the
barometer is steady, and the wind is almost
calm. The swell is now about nine feet and
coming in every eight seconds.

38. 36 hours before landfall:
The first signs of the storm appear. The
barometer is falling slightly, the wind is
around 11 mph, and the ocean swell is
about 13 feet and coming in seven
seconds apart.

39. On the horizon, a large mass of white cirrus
clouds appear. As veil of clouds
approaches, it covers more of the horizon.
A hurricane watch is issued, and areas with
long evacuation times are given the order
to begin.

40. 30 hours before landfall:
The sky is covered by a high overcast.
The barometer is falling at .1 millibar per
hour; winds pick up to about 23 mph. The
ocean swell, coming in five seconds apart,
is beginning to be obscured by wind- driven
waves and small whitecaps begin to
appear on the ocean surface.

42. SATELLITE- is the most advance technology
used in monitoring a cyclone or
typhoon. It can visualize exactly in
real time the formation and the path
of a cyclone.

43. Doppler RADAR
is an acronym for Radio Detection and
Ranging. Radar detection devices emit
and receive radio waves to determine the
distance from the source to the object by
measuring the time if it takes for the echo of
the wave to return.

44. Specifically, weather radar measures the
direction and the speed of moving objects,
such as precipitation, and has a capacity
to measure the velocity of the particles in
order to determine the rate of which the
particles are falling.

45. HOW DOES A
DOPPLER RADAR
WORK?

47. Preparedness
and Mitigation

48. The following preparedness and
mitigation strategies are adopted from the
Department of Education’s Disaster Risk
Reduction Resource Manual issued on 2008:

49. Preparedness (What to do before):
• Establish and maintain coordination with
Barangay Disaster Coordinating Councils
(BDCC) and personnel.
• Ensure that house can withstand heavy
rain and strong winds.

50. • Learn more about typhoon and other
weather disturbances, their signs and
warnings, effects and dangers and
how to protect house and other
properties.
• Learn something relevant to mitigation
and preparedness for tropical
cyclones.
• Participate actively to school’s disaster
response-drill or simulation.

51. Response (What to do during):
• Monitor through radio or other reliable
sources the latest official report of PAGASA
on the typhoon.
• When house is no longer safe, evacuate
immediately to safer place

52. • Stay indoors and away from windows.
• Keep an open line of communication.
with relatives that are not affected to keep
them posted.
• Ensure that members of the family will
remain calm by keeping them informed of
the latest developments.

53. Rehabilitation (What to do after):
• Help in attending the victims immediately.
For minor cuts and wounds apply first aid.
• In case of major cuts and wounds, seek
necessary medical assistance at disaster
station or hospital.

54. • Help in checking the house for damages
and losses. Note damages that require
immediate repair, e.g. electrical
connections and water supply.
• Coordinate with Barangay officials and
LGU’s for assistance.

55. Preparedness (What to do before):
Develop a Family Preparedness Plan
In case of severe thunderstorm – specific
planning should include the following:

56. • Learn more about your area’s severe
thunderstorm risk.
• Discuss how you would know if a
thunderstorm may produce a tornado.
• Discuss how to be warned of an
approaching thunderstorm.

57. • Recommend trimming and removal of
dead or rotting trees that could fall and
may cause damage or injury.
• Secure outdoor objects that could be
blown away and cause damage.
• Secure house doors and windows both
from the inside and outside.

58. • Learn how to estimate the distance of the
thunderclouds by computing the difference
in time(second) between seeing the flash
of lightning and hearing the claps of
thunder. (1 second = 1000 ft.).

59. Response (What to do during):
• Learn to do the lightning safety position
and stay away from structures, trees,
towers, fences, telephone lines, or power
lines if out in the open.
• Carefully watch out for falling debris and
flash floods.

60. • Stay calm throughout the occurrence of
thunderstorm.
• Postpone all outdoor activities.
• Avoid plumbing and bathroom fixtures
that are good conductors of electricity.

61. • Unplug or turn off all appliances and
other electrical items such as computers.
• Turn off air conditioner and television and
stay off the phone until the storm is over.
Use a battery operated radio for gaining
information.

62. • Choose and move to a ‘safe place’ in
your house (if there is any) where members
of the family can gather together during a
thunderstorm preferably on lowest floor of
your house. Where there are no windows,
skylights, or glass doors, which could be
broken by strong winds or hail, causing
damage or injury.

65. “Lightning safety experts have
invented a ‘lightning safety position’ that is
very important to know if you are caught in
a thunderstorm and you can’t find a
shelter.
FOLLOW THE LIGHTNING SAFETY
POSITION for:
 It makes you a smaller target

66. With your heels together,if lightning hits the
ground, it goes through the closest foot,
up to your heel and then transfers to the
other foot and goes back to the ground
again. If you don’t put your feet together,
lightning could go through your heart and
kill you. You put your hands over your ears
to protect them from thunder.”
(Lightning Safety Experts)

67. Preparedness (What to do before):
• Develop a preparedness plan for the whole
family.
• Have periodic drills with the members of the
family.
• Inspect pre-designated areas to ensure the
best protection.

68. • Keep an open line communication with
other members of the family.
• Listen to radio and television for
information.
• Store flashlights and back-up batteries to
receive warnings reponse.

69. Response (What to do during):
• Move to pre-designated area or an interior
room on the lowest floor and get under a
sturdy piece of furniture.
• Stay away from windows.
• Lie flat in a depression if caught outside
your house/ school or any building.

70. Rehabilitation (What to do after):
• Attend to survivors immediately.
• Check the house for damages and losses.
• Coordinate with proper authorities for
assistance.

71. Preparedness (What to do before):
• Find out the frequency of occurrence of
floods in locality, especially those that affect
your area.
• Know the flood warning system in your
locality. If none exists, recommend to the
appropriate authority for the creation of one.

72. • Research from previous occurrences how
fast the water floods occur in your area and
how it rises.
• If it has been raining hard for several hours,
or steadily raining several days, be alert to
the possibility of a flood. Floods happen as
the ground becomes saturated.

73. • Watch out for rapidly rising water and help
prepare the family for evacuation.
• Switch off the electricity and lock the
rooms after all have gone out.
Have a handy survival kit. It should contain
battery operated transistor radio,

74. flashlight, emergency cooking equipment,
candies, matches, and first aid kit.
• Use a radio or a portable, battery-powered
radio (or television) for updated information.
Local stations provide the best advice for
your particular situation.

75. Response (What to do during):
• Stay calm and keep updated with the
status of the situation and safety reminders
on what to do and where to go in case of
evacuation.
• Listen continuously to a radio, or a
portable, battery-powered radio (or
television) for updated emergency
information.

76. • Do not attempt to cross flowing streams
unless assured that the water is below knee
high level.
• Avoid areas prone to flash flooding and be
cautious of water- covered roads, bridges,
creeks and stream banks and recently
flooded areas.

77. • Do not go to swimming or boating in
swollen rivers.
• Watch out for snakes in flooded areas.
• Eat only well-cooked food and drink only
clean or preferably boiled water and throw
away all food that has come into contact
with flood water.

78. Rehabilitation (What to do after):
• Report broken utility lines (electricity, water,
gas, etc.) immediately to appropriate
agencies/authorities.
• Ensure that electrical appliances are
checked by a competent electrician before
switching them on.

79. • Avoid affected areas.
• Continue to listen to a radio or local
television stations and return home only
when authorities indicate it is safe to do so.
• Stay away from any building that is still
flooded.

80. Preparedness (What to do before):
• Know the storm surge risk zones and
identify safer grounds for relocation if
necessary.
• Ensure that everyone is familiar with the
identified escape routes of the family to
higher grounds.

81. • Stay off the beach when weather
disturbance exists.
• Help establish evacuation plans and
procedures.
• Participate in the regular conduct of drills
and exercises.

82. Response (What to do during):
• Immediately move to higher grounds
upon detection of signs of a probable
storm surge or upon receiving a warning
that a storm surge is eminent.
• Be alert of and stay away from steep,
high coastal areas which are prone to
landslides.

83. • Switch off power supply.
• Stay on the on the inland side away
from the potential flow of water.
• If caught in a storm surge, take hold of
large boulders or tree trunks which can
provide protection from the force of
water or debris carried by the flowing
water.

84. Rehabilitation (What to do after):
• Do not eat fresh food that came in
contact with flood waters.
• Drinking water should be submitted to
proper authorities for testing.
• Check damage of the house to ensure
that there is no danger of collapse.

85. • Check house for electrical damage
and open live wires. Electrical fixtures
should only be switched on after making
sure that is safe to do so.
• Help clean all mud and debris
immediately.

87. The following are examples of
hydrometeorological hazard maps.

91. PROJECT NOAH by the department of
science and technology(DOST)
- a project for scientific forecasting, monitoring,
assessment and information services regarding
natural hazards
- a more accurate, integrated, and responsive
disaster prevention and mitigation system,
especially in high-risk areas throughout the
Philippines

92. Project NOAH (Nationwide Operational
Assessment of Hazards)
The project will harness
technologies and management
services for disaster risk reduction
activities offered by the DOST through
PAGASA, PHIVOLCS, and the DOST-
Advance Science and Technology
Institute (ASTI), in partnership with the
UP National Institute of Geological
Sciences and the UP College of
Engineering.

93. The Project has the following components:
1. Distribution of hydrometeorological
devices in hard-hit areas in the Philippines
(Hydromet). A total of 600 automated rain
gauges (ARG) and 400 water level
monitoring stations (WLMS) will be installed
along the country’s 18 major river basins
(RBs) by December 2013 to provide a better
picture of the country’s surface water in
relation to flooding.

94. 2. Disaster Risk Exposure Assessment for
Mitigation – Light Detection and Ranging
(DREAM-LIDAR) Project. The project, which is
targeted to be completed by Dec. 2013,
aims to produce more accurate flood
inundation and hazard maps in 3D for the
country’s flood-prone and major river
systems and watersheds.

95. 3. Enhancing Geohazards Mapping through
LIDAR. The project which is targeted to be
completed by December 2014, shall use
LIDAR technology and computer-assisted
analyses to identify exact areas prone to
landslides.

96. 4. Coastal Hazards and Storm Surge
Assessment and Mitigation (CHASSAM).
CHASSAM, which is targeted to be
completed by December 2014, will
generate wave surge, wave refraction,
coastal circulation models to understand
and recommend solutions for coastal
erosions.

97. 5. Flood Information Network (floodNET)
Project. Targeted to be complete by
December 2013 is the flood center that will
provide timely and accurate information
for flood early warning systems. The
FloodNET Project will come up with
computer models for the critical RBs,
automate the process of data gathering,
modelling and information output, and
release flood forecasts.

98. 6. Local Development of Doppler Radar
Systems (LaDDeRS). LaDDeRS seek to
develop local capacity to design, fabricate,
and parameters of sea surface such as
wave, windfield, and surface current
velocity.

99. 7. Landslides Sensors Development Project.
This project is a low cost, locally developed,
sensor based early monitoring and warning
system for landslides, slope failures, and
debris flow. As of May 2012, 10 sensors have
been installed in:

100. San Francisco, Surigao del Norte; Tago,
Surigao del Sur; Tublay, Buguias, and Bokod
in Benguet; Guihulngan City, Negros
Occidental; St. Bernard, Southern Leyte;
and Tubungan, Iloilo. Additional sensors are
expected to e deployed to not less than 50
sites by 2013.

101. 8. Weather hazard Information Project
(WHIP). WHIP involves the utilization of
platforms such as television (DOSTv) and a
web portal (http://noah.dost.gov.ph), which
display real-time satellite, Doppler radar,
ARG and WLMS data to empower LGUs and
communities to prepare against extreme
natural hazards. This is complimented by
activities, such as:

102. a) conducting IEC (Information, Education,
and Communication) activities;
b) the processing and packaging of
relevant and up-to-date information for
public use.