Transcript Cyclone Heta - Western Springs College

91007 DEMONSTRATE GEOGRAPHIC UNDERSTANDING OF
ENVIRONMENTS (NIUE) THAT HAVE BEEN SHAPED BY TROPICAL
CYCLONE HETA 2004
You need “to fully explaining aspects of how extreme natural event(s)
shape natural and cultural environments using geographic terminology
and concepts, and showing insight, integrating detailed supporting
evidence”.
Geographic understanding refers to an understanding of how natural environments
and people interact and the consequences of that interaction.
Extreme natural event(s) refers to one type of naturally occurring hazard that has a
major impact on people’s lives, such as: earthquakes, floods, tsunami, landslides,
tropical cyclones.
Supporting evidence refers to specific, relevant information from different
environments.
Environments refer to either different places that are affected by one type of
extreme natural event or different places that are affected by a single extreme
natural event.
Integrating refers to relevant examples being woven throughout the evidence to
support explanations.
91007 DEMONSTRATE GEOGRAPHIC UNDERSTANDING OF
ENVIRONMENTS (NIUE) THAT HAVE BEEN SHAPED BY TROPICAL
CYCLONE HETA 2004
Exam questions are selected from:
•
Natural and cultural characteristics (features) of the environments that make
them vulnerable to the extreme natural event(s)
•
Natural processes that operate to produce the extreme natural event(s)
•
Effects of the extreme natural event(s) on the natural environments
•
Effects of the extreme natural event(s) on the cultural environments
•
How different groups of people have responded to the effects of the extreme
natural event(s).
CYCLONE HETA: NIUE
Cyclone Heta reached hurricane strength on New Year's Day 2004 in a deserted
part of the Pacific Ocean. After travelling to the Tokelau Islands it retraced its
track, heading for Western Samoa where it caused heavy damage.
From 4-6 January it headed in a beeline for Niue, while increasing in strength to
the most ferocious storm known to man, a class five hurricane with wind speeds
of over 250km/h. Also accelerating its speed to over 30km/h, it turned its most
devastating flank to Niue, destroying the capital village Alofi and killing a nurse
who sacrificed her life to save her baby.
NIUE LOCATION
Niue is a small independent state, located between Tonga on the west and the Cook
Islands further east.
Niue is only a small limestone island, measuring about 23 by 18 km with a total surface
area of 250km2. It rises to only 68m above sea level, with most of the island no higher than
30m.
Its population is estimated at 1400-1800, with around 200-300 tourists enjoying the clear
waters, caves and calving humpback whales in winter (Aug-Oct). However, most of the
20,000 Niueans live in Auckland, New Zealand and another 2000 in Australia.
Located 19 degrees south of the Equator, Niue experiences regular trade winds from the
south-east, which renders the coast of this part of the island inhospitable. Understandably,
the NW side of the island is more sheltered, reason why most of its population and tourist
activities reside here, and goods are landed here by ship. But this is also the side facing
the path of cyclones and their most vicious winds. Niue does not have a protected
harbour but a shallow quay, approached by boats along the line joining two navigational
lights. Locally based boats and fishing vessels need to be lifted out of the water when
storms rage.
CULTURAL FEATURES THAT
MAKE NIUE VULNERABLE
Main settlement on NW coast
Eg capital Alofi, airport,
main coast road.
Most developments coastal
eg hospital.
Hotel Niue
Huanaki culture centre
Fuel tanks and telecom dish
Niue adventure and
Alofi Rentals, Dive Niue
NIUE ADVENTURE AND ALOFI RENTALS
HUANAKI CULTURE CENTRE
FUEL TANK
HOTEL NIUE
DIMITRY VILIAMU’S HOME
NATURAL FEATURES THAT MAKE NIUE VULNERABLE
limestone island 23 by 18 km
68m above sea level, with most of the island no
higher than 30m.
NW side of the island is more sheltered
Niue does not have a protected harbour but a
shallow quay
Regular trade winds from the south-east, which
makes the SE coast inhospitable
NATURAL PROCESSES THAT OPERATE TO
PRODUCE THE TROPICAL CYCLONE
Heta formed at 10 degrees south of the
equator where trade winds are strong and
The Pacific ocean was heated to 27 degrees C.
The waves produced by the trailing winds are as a result much more powerful such that a
hurricane's left flank (in the southern hemisphere) is the most damaging one. As cyclone
Heta passed 70km west of Niue, it presented its most devastating flank to the island.
Tropical cyclones use warm, moist air as fuel. That is why
they form only over warm ocean waters near the equator.
The warm, moist air over the ocean rises rapidly upward
from near the surface and becomes saturated with
evaporated moisture. This means that there is less air left
at the surface (i.e. low pressure). Air from surrounding
areas with higher air pressure pushes in to the low
pressure area to try to equalise the pressure. Then that
“new” air becomes warm and moist and rises, too. As the
warm air continues to rise, the surrounding air swirls in to
take its place. Trade winds cause the moist air to spin
inwards. As the warmed, moist air rises and cools off, the
water in the air forms towering cumulonimbus
thunderclouds (because there is a huge amount of
condensation). The whole system of clouds and wind
spins and grows, fed by the ocean’s heat and water
evaporating from the surface. The diagram below shows a
cross section through a tropical storm.
As the storm system spins faster and
faster, an eye forms in the centre. It is
very calm and clear in the eye, with
very low air pressure.
BBC animation - the formation of a
hurricane
http://news.bbc.co.uk/2/hi/science/nat
ure/4588149.stm
Latitudes 5-15 N and S
of the equator
Sea temperature
26.5-27 C
Warm, Moist air rises and
Starts to condense as it cools
Forming towering
cumulo nimbus clouds
Inter Tropical Convergence Zone
Where NE and sE Trade winds meet
Is an area of rising air
Coriolis force, caused by the rotation of the earth,
Starts to rotate the rising air in a clockwise direction
(S Hemisphere) around an eye that is calm
Once the tropical cyclone forms, it
Moves in a SE direction over the warm ocean,
Which provides energy,moisture and heat.
As it moves to lower latitudes, the
ocean becomes cooler, it loses energy
And becomes a depression
How has TC Heta caused changes to the natural
environment of Niue?
These factors combined with the 7 metre storm surge and the 10 metre
waves and 300km/h gusts of wind meant the damage that was done
to Niue and its capital Alofi was extensive.
Heta flooded Niue with 4-7m storm surges and 10 metre waves that
washed 100m inland
Coral was removed from the reef and deposited onto the beach front
by the storm surge.
Storm surge eroded the beach front and created steep banks. It also
demolished substantial amounts of vegetation on its way.
Coral reef was removed from 200m below sea level.
Salt water contaminated fresh water.
Wind gusts up to 300 km/h caused severe damage
80% of the trees had their foliage ripped off.
Coconut trees were uprooted.
Some of the foliage that remained was killed by the salt spray that was
whipped up by the wind and killed vegetation
The huge period of drought after the cyclone provided the island with
a large fire risk
How has TC Heta caused changes to the cultural
environment of Niue?
One life lost. The capital city of Alofi, which took the brunt of the storm, was devastated as
most of the commercial and financial areas were wiped out by the high winds.
Hundreds of homes destroyed.
200 residents made homeless – 10% of population.
The hospital was basically destroyed.
Fresh water supplies contaminated with salt water
Sewage pumps no longer worked.
No running water available.
People traumatised and needing counselling. Hotel Niue destroyed.
Damage to communications and electronic infrastructure was also great as the
storm damaged a satellite dish and disabled 75% of Niue's computer database.
$240,000 loss of crops, i.e. coconut and fruit plantations.
Loss of tourism income from expected 2700 tourists (based on 2003 statistics)
Satellite dishes and phone systems knocked out.
Bulk fuel storage facility ruined and all fuel leaked into the sea.
STORM SURGES AFFECT LOW ISLANDS
HOW HAVE DIFFERENT GROUPS OF PEOPLE RESPONDED TO THE
EFFECTS OF THE EXTREME NATURAL EVENT(S).
Land use Zoning and Buffering zones
Growing mainly root crops such as taro and Yams
Build on elevated areas of the island
Build reliable communications networks that are secure.
Strict building codes which can withstand strong winds and rains.
Good meteorological services which leave people with adequate time to
prepare.
Educating public on how to prepare for a Cyclone.
Insurance policies in place
Identification of flood prone areas
Build flood proof structures such as stop banks
Have an emergency plan set-up
Grow crops that can be harvested before the cyclone season.
Clean-up costs $20 million (emergency response and start of recovery)
Estimated cost of rebuilding is over $25 million.
NZ and Aussie military aid workers arrived and assisted in urgent relief,
such as dist of food and medicines. Evacuation centres were set up to
assist hundreds of people whose homes were destroyed.
NZ Gave 5 million and the EU gave over 700,000. NZ sent two airforce
hercules plus ships with supplies to help rebuild.
A donor team comprising representatives from seven countries worked
with NZ authorities to help with relief efforts.
Seventy eight people were airlifted to NZ four of them required
medical treatment.
the capital Alofi be relocated in the centre of the island.
THE DAMAGE HETA CAUSED ON TONGA, NIUE, AND AMERICAN SAMOA
WAS ESTIMATED AT $150 MILLION DOLLARS (2004 USD), WITH MOST OF THE
DAMAGE OCCURRING IN AMERICAN SAMOA
https://www.youtube.com/watch?v=oftpEUjH5p4 (Samoa)
Formed: January 2, 2004 (2004-01-02)
Dissipated: January 8, 2004 (2004-01-09)
Highest winds: 215 km/h (130 mph) (10-minute sustained)
260 km/h (160 mph) (1-minute sustained)
Lowest pressure: 915 hPa (mbar)
Fatalities: 1 direct
Damage: $150 million (2004 USD) $170 million (2009 USD)
Areas affected: Samoa, Tonga, Niue, American Samoa
In Tonga, Heta's strong winds damaged houses and caused severe crop
damage, mostly to breadfruit, mango, tava and bananas.
In Tafahi and Niuatoputapu, 50-100% of the homes and buildings were destroyed
by the cyclone's powerful, Category 5 winds.
However, because of advanced warnings, there were no deaths or injuries.
Structural damage in Tonga amounted to $160,000 dollars (2004 USD).
TRACK OF HETA TO SE.
SAMOA
Seawalls constructed after the major cyclones Ofa and Val in 1990-91 and other
emergency measures helped to reduce the damages caused by Heta.
Power, water, transport and other services were restored within a week after the cyclone
passed near the Island.
Nonetheless, the cyclone caused major
damage. Trees, crops and coastal
infrastructure were destroyed or damaged.
Damage added up to an estimated
US$ 25 million -- beyond the financial capacity
of the government.
Also, the fringing reef that provides
natural protection was also badly damaged.
Samoa's international airport has already
been closed
AMERICAN SAMOA
American Samoa on Sunday, uprooting banana trees, swirling debris into the
streets
With sustained winds of 144 mph and gusts of 173 mph, Heta was moving south at
about 12 mph Sunday and was forecast to pass within 150 miles southwest of
American Samoa's capital of Pago Pago
Hundreds of people hoping to travel from Pago Pago to Apia or vice versa were
stranded, and Hawaiian Airlines canceled a flight from Honolulu to Pago Pago —
some 2,300 miles south — on Sunday.
In Pago Pago, high school football players from Hawaii were reportedly riding out
the storm in their hotel rooms.
Three people were washed out to sea at Fagasa, but managed to make it safely
back to shore as families in coastal areas were advised to move to higher ground
Pago Pago International Airport closed