STORM SURGE
(DALUYONG NG BAGYO)
Presented by:
ROMEO B. GANAL, Jr. , WSI, Meteor
Local Weather and Flood Forecaster
Northern Luzon PAGASA Regional Services Division
Capitol Hills, Tuguegarao City
Typhoon Yolanda
Hurricane Katrina (US)
Normal Water Level
Storm Surge is
different from
Tsunami
=
Storm
Tsunami
Surge
Tropical Cyclone
Storm surge is a sudden, temporary and abnormal rise of
seawater above normal sea level causing big waves at the
coast, generated by the strong winds and low atmospheric
pressure of a typhoon.
BEFORE
Storm surges BEFORE
can engulf low-lying coastal AFTER
AFTER communities and
can also bring destruction to natural and man-made
structures.
It is the DEADLIEST threat from tropical cyclones.
BEFORE BEFORE AFTER
AFTER
Inland Extent
Storm surge can penetrate well inland from the coastline.
During Typhoon Yolanda, the surge moved inland nearly
1000 metres (1KM) in some locations in Visayas.
Effects of Storm Surge
Significant destruction of property, structures,
vegetation, and coastal landscapes are just a
few of the many impacts that result from
storm surge.
A secondary effect of storm surge is salt water
inundation and its effect on vegetation (dying
or dead vegetation).
How high will the Storm Surge be?
Factors that influence Storm Surge
1. The Right-Front-Quadrant
2. Storm Size and Intensity
3. Storm Forward Speed
4. Central Pressure
5. Angle of Approach
6. Shape of the Coastline
7. Bathymetry
8. Local Features
How high will the Storm Surge be?
Right-Front Quadrant
The maximum effects of a storm are usually felt within the
right-front quadrant. Here the winds are usually the
strongest, storm surge is highest.
How high will the Storm Surge be?
Storm Size and Intensity
The stronger the winds of the tropical cyclone, the lower the atmospheric
pressure, the higher the storm surge.
How high will the Storm Surge be?
Storm Size and Intensity
The stronger the winds of the tropical cyclone, the lower the atmospheric
pressure, the higher the storm surge.
How high will the Storm Surge be?
Storm Forward Speed
The faster the cyclone crosses the coast, the more quickly the surge
builds up and the more powerfully it strikes.
FAST-MOVING CYCLONE: (24 TO 56 KPH)
The surface wind stress is increased in the right-front quadrant thus
creating a higher storm surge on the outer cost versus the storm
surge from a slow moving hurricane.
SLOW-MOVING CYCLONE: (0 TO 23 KPH)
A slow moving cyclone may produce the opposite effect inside a bay,
or river system. This is because slow moving cyclones have more time
to pump water into inland water bodies than do fast moving cyclones.
How high will the Storm Surge be?
Central Pressure
Minimal contribution in comparison to the wind.
Tropical Cyclone
How high will the Storm Surge be?
Angle of Approach
The more perpendicular the angle of approach to
the coast, the higher the surge.
Perpendicular Approach
How high will the Storm Surge be?
Angle of Approach
The more perpendicular the angle of approach to
the coast, the higher the surge.
Parallel Approach
How high will the Storm Surge be?
Angle of Approach
The more perpendicular the angle of approach to
the coast, the higher the surge.
Perpendicular Approach
Diagonal Approach
How high will the Storm Surge be?
Shape of the Coastline
Storm surge will be higher when a cyclone
makes landfall on a concave coast rather than a
convex coast.
Concave Coast (Papaloob) VS. Convex Coast (Papalabas)
How high will the Storm Surge be?
Bathymetry
Before the Surge
Shallow Slope
After the Surge
How high will the Storm Surge be?
Bathymetry
Before the Surge
Steep Slope
After the Surge
How high will the Storm Surge be?
Bathymetry
Before the Surge After the Surge
Shallow Slope VS. Steep Slope
How high will the Storm Surge be?
Local Features
Bays, inlets, RIVERS
headlands,
mouths of rivers
BAY
and offshore
islands can
funnel and
heighten the CONCAVE COAST
storm surge.
How high will the Storm Surge be?
RIVER
BAY
Wave Setup
Wave setup occurs when
waves continually break onshore
and the water from the runup
piles up along the coast because
it can’t get back out to the sea.
The water level therefore rises as
a cyclone approaches, especially
since the waves become larger
and more water is pushed
onshore.
The frequent arrival of
breaking waves on the Philippine
coastline was a major factor in
the flooding caused by Typhoon
Haiyan (2013).
Risk of Storm Surge
LAND LAND WATER LAND
WATER
WATER
(DEFINITELY) SAFE (STILL) SAFE
SAFE
Risk of storm surges is decided by
the difference between water level
WATER and land height.
WATER LAND LAND
DANGEROUS VERY DANGEROUS
Storm Surge Occurrences in the
Philippines
Typhoon Pedring
(Nesat)
in Manila Bay
September 27, 2011
Storm Surge Occurrences in the
Philippines
Typhoon Pedring (Nesat) in Santa, Ilocos Sur
September 27, 2011
Storm Surge Occurrences in the
Philippines
Storm Surge Occurrences in the
Philippines
Storm Surge Occurrences in the
Philippines
Typhoon Yolanda
(Haiyan) in Samar and
Leyte
November 8, 2013
What to do when a Storm Surge
happens?
If a storm surge has the potential to impact a coastal
community, PAGASA issues a warning relative to the
danger it might bring and/or delivers warnings
through various media including news services thru
television and radio and social media such as
Facebook and Twitter.
What to do when a Storm Surge
happens?
Listen for Warnings
www.facebook.com/PAGASA.DOST.GOV.PH
www.pagasa.dost.gov.ph
@dost_pagasa
What to do when a Storm Surge
happens?
Be Prepared
1. Determine if your home is in a vulnerable area.
2. Be aware of concrete, reinforced multi-storey buildings
for evacuation purposes.
3. Identify the quickest way to get to a high safe ground.
4. Conduct evacuation drills.
5. Important documents (i.e., birth certificates, insurance
policies, passports etc.) should be stored safely in a
waterproof area or box.
What to do when a Storm Surge
happens?
THANK YOU!
Website:
bagong.pagasa.dost.gov.
ph
Facebook:
www.facebook.com/
pagasa.dost.gov.ph
Twitter:
@dost_pagasa
Typhoon Flood
+632-9271541 +632-9266970
+632-9271335 +632-9204052
+632-9264258 +632-9282754
+632-9272877 +632-9294065
NLPRSD (078) 304- 2109
(078) 304-1994
