Tropical Cyclones Affecting the Karratha/Dampier/Roebourne
region
Tracks
| Flooding |
Storm Surge |
Notable TCs
| TC Orson | TC
John, Steve, Rosita report (1.5MB pdf)
The Pilbara coast experiences more cyclones than any other part of Australia.
Since 1910 there have been 48 cyclones that have caused damaging wind
gusts in excess of 90 km/h in the Karratha, Dampier and Roebourne region.
On average this equates to about one every two years. About half of these
cyclones have an impact equivalent to a category one cyclone. Ten of these:
1925, 1939, 1945, 1954, Shirley 1966, Sheila-Sophie 1971,
Trixie 1975, Chloe 1984, Orson 1989 and John
1999 have caused very destructive wind gusts in excess of 170 km/h*.
Along the central Pilbara coast the cyclone season runs from mid December
to April peaking in February and March as shown in the graph of monthly
occurrence.
The early accounts of cyclones on the central Pilbara coast focus upon
the impact on the pearling fleet and to the settlements at Cossack, Wickham
and Roebourne.
Since the 1960s the development of the mining and offshore oil and gas
industries has increased the damage potential of cyclones. Substantial
economic losses can be incurred even with the threat of a cyclone impact
owing to lost production or disruptions to shipping activities. Fortunately
the modern towns of Karratha and Dampier have been built according to
cyclone wind ratings and are far less susceptible to damaging winds than
those properties in earlier times.
Figure 1. Tropical Cyclone in the Dampier/Karratha area. Click on image
to enlarge.
*Note: Wind gust speeds for events prior to 1961 have been estimated
using the available mean wind speeds, mean sea level pressure, and damage
reports.
Tracks
Cyclones that impact the central Pilbara coast typically form over warm
ocean waters to the north of the state. Although the typical initial steering
of these systems is to the southwest, those that affect the Karratha region
take a more southerly or southeasterly track as they move further south
as shown in figure 1. Some cyclones such as Trixie (1975), Chloe
(1984) and Monty (2004), originate from near the West Kimberley
and take a west to southwest track toward the Pilbara.
See also the Interactive
Tropical Cyclone Plotting web page to access tracks of historical
tropical cyclones.
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Figure 2. Tracks of notable cyclones affecting
the Dampier and Karratha area. Click on image to enlarge.
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Figure 3. Monthly occurrence of cyclones affecting
the Karratha and Dampier area. Click on image to enlarge.
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Flooding
By not being on a major river, Karratha and Dampier are not at risk
of major flooding caused by rainfall alone. Localised flooding is certainly
possible in susceptible areas along creeks and low-lying areas. Major
flooding in Karratha and Dampier is typically associated with storm surge,
as discussed in the next section. Flooding was a feature of historical
cyclone events affecting Roebourne on the Harding River. However, the
construction of the Harding River Dam, some 20 km upstream of the town,
in 1983-84 has eased the flood threat to the town.
Heavy rainfall inland can cause flooding along the neighbouring major
river systems such as the Fortescue, Sherlock and Maitland that can impact
pastoral stations, mining activities and cause transport delays and damage
to road and rail infrastructure. For example, during TC Monty in
2004 the bridge over the Maitland River was destroyed cutting road links
along the North West Coastal Highway and the Harding River Dam overflowed
(see photos).
The flood potential of a system is not directly related to cyclone intensity
but is associated with its track, speed and areal extent. Indeed rainfall
totals in excess of 100 mm are common with tropical lows that move over
land. In February 1997 a slow moving low moved over the west Kimberley,
Pilbara and Gascoyne causing rainfall in excess of 400 mm in parts and
one of the highest ever floods along the Ashburton River.
Storm Surge
Storm surge is a major threat to the Karratha region. The actual water
level, called the storm tide is a combination of the storm surge and tidal
variation. The worst case scenario is to have a severe cyclone pass near
the town near the time of high tide, in which case the water level will
be many metres above the highest astronomical tide. Given the significant
tidal variations, this is a rare occurrence. Storm surge is a complex
function of cyclone intensity and motion, extent of maximum winds, bathymetry
and coastline shape. Even with an intense cyclone the highest surge is
typically restricted to less than 80 km of the coast owing to the nature
of the extent of a cyclone's maximum winds.
The graphic impact of TC Vance on the remote coast west of Onslow
indicates how a storm surge can change the appearance of the coastline
(see TC
Vance). The early account of a cyclone in 1881 when part of
the coast near Cossack had two sand ridges completely eroded away, demonstrated
to the early pioneers the devastating potential of the storm surge. Fortunately
there has not been a significant storm surge at Karratha or Dampier since
the 1960s.
Some Notable Cyclones Impacting Karratha, Dampier
and Roebourne
|
Tropical Cyclone
|
Wind Gust
(km/h)
|
Impact Description
|
|
24-25 Dec 1870
|
-
|
A cyclone passed near Roebourne on Christmas
morning, the pressure falling to 956 hpa. The cyclone caused damage
to buildings and boats. Trees were so thoroughly denuded of foliage
that the landscape was described as similar to that in winter in England. |
|
6-7 Jan 1881
|
-
|
Sixteen people died as all but one large
schooner either foundered or was washed ashore. Parts of the coastline
were completely changed and two lines of sand hills were eroded away,
indications of a significant storm surge. |
|
7 March 1882
|
-
|
A severe cyclone passed Roebourne and Cossack
in the evening causing damage to every building in the settlements.
Cossack recorded a minimum pressure of 942 hPa. Despite the extensive
loss of sheep from surrounding stations it was considered fortunate
that only one person suffered an injury. |
|
1 March 1889
|
-
|
Flooding was considerable at Cossack where
the cyclone coincided with high tide. All crew aboard the Waratah
were lost off Cape Preston and one man drowned in the river at Roebourne. |
|
4-9 Jan. 1894
|
-
|
Within the space of five days two cyclones
crossed the Pilbara coast. The first caused damage to many buildings
at Roebourne and Cossack. The second cyclone caused more significant
damage to the area completely washing away the previously damaged
sea wall at Cossack. Over forty lives were believed to have been lost
as twelve luggers and the steamer Anne were destroyed. Altogether
the damage was estimated at 15000 pounds and the loss of some 15000
sheep. Flooding was also substantial. |
|
2 April. 1898
|
-
|
A cyclone was described as causing more
damage at Cossack than had ever been experienced before. Tramway,
rails, road and bridges were destroyed and telegraph line downed.
Houses collapsed and all boats slipped their moorings. The damage
was estimated at over 30000 pounds. Whim Creek registered 747 mm of
rain in 24 hours, the highest daily rainfall ever recorded in WA. |
|
4 Jan. 1911
|
-
|
A cyclone affected the Pilbara coast between
Cossack and Onslow. The Glenbank was wrecked off Legendre Island
with the loss of all but one of its crew. The cyclone crossed near
Mardie station where nearly every outbuilding was levelled to the
ground and 6000 gallon tanks were blown away. |
|
21-22 March 1912
|
-
|
This cyclone crossed the coast just west
of Balla Balla, the port for the copper mines of the Whim Creek district,
early on the 22nd. Damage extended more than 200 kilometres along
the coast. A large, iron sailing ship, the Crown of England,
was wrecked on Depuch Island; a similar vessel, the Concordia,
was driven ashore nearby. Several lighter vessels and pearling luggers
were sunk or wrecked. The Koombana was lost at sea off Port
Hedland with none of the 140 people aboard surviving. In total the
cyclone claimed well over 150 lives. |
|
21 Jan.1925
|
102 est.
|
Only a very small portion of the land
end of the Point Samson jetty was left intact. Almost 5 km of the
tramline was washed away and the Pope's Nose Creek bridge was badly
damaged.
At Cossack the sea in the creek rose 7.2 m, covering the road and
surrounding country for about a mile (1.6 km). Seven luggers and a
schooner which had sheltered in Cossack Creek were lifted 100 m into
the mangroves by the storm surge.
Not a building was left unscathed in Roebourne. Residents sheltered
in more substantial stone buildings as the timber houses were razed.
The Jubilee Hotel was unroofed and the other two hotels badly damaged. |
|
11 Jan. 1939
|
>117
|
Nine people died with the loss of the Nicol Bay, on a holiday
cruise to the Ashburton River. Some Roebourne properties sustained
damage.
|
|
6 Mar 1945
|
>117
|
Severe damage was done to Roebourne and Point Samson. The Harding
River broke its banks and flooded back yards.
|
|
31 Dec. 1954
|
.
|
Every building was damaged in Roebourne.
The Point Samson jetty was wrecked and a locomotive shed and workshop
demolished. Damage was conservatively estimated at 50,000 pounds.
The eye passed over Lewis Island driving ashore the Dulverton
then moved over Roebourne from 3:20 to 4:30 pm. Damage was extensive
at Coolwanyah and Pyramid stations. |
|
|
-
|
A cyclone moved parallel to the Pilbara coast before heading down
the west coast. The Point Samson jetty was washed away and many
telegraph lines from Roebourne to Onslow were blown down. The Harding
River flooded into Roebourne.
|
|
|
204
|
Shirley passed crossed the coast at King Bay where a ship
recorded winds to 204 km/h. In Roebourne, winds destroyed some buildings.
Sherlock station recorded 404 mm and subsequent floodwaters damaged
the Mount Goldsworthy and Hamersley iron-ore railways under construction,
roads and other facilities along the Northwest coast. However, considering
the intensity, the cyclone caused only minor damage.
|
|
|
|
At Wickham more than 30 houses were partly unroofed and some houses
received major damage. There was no damage to buildings in Dampier,
Roebourne or Karratha as the cyclone crossed the coast well to the
east. Kerry passed close to a number of oil-drilling rigs
causing damage and lost productivity time that cost over one million
dollars.
|
|
Trixie, 19 Feb 1975
|
259 (Mardie)
|
Trixie moved along the central Pilbara coast affecting many
communities from Roebourne to Onslow, where the worst damage occurred.
Property damage at Dampier was estimated at $900,000. Three blocks
of flats were unroofed, as were two blocks of single men's quarters.
A concrete block garage collapsed when a service station roof landed
on it. Windows were blown in. At the Cape Lambert facility, doors
and roofs were damaged at the workshop and warehouse. The Ore Processing
plant lost cladding from sheds and a transportable electrical workshop
disintegrated. Point Samson, Roebourne and Wickham all sustained
major property damage.
|
|
Chloe, 29 Feb. 1984
|
193
|
Chloe crossed the coast near Roebourne where three houses
were destroyed and twelve others unroofed. Fifty people required
evacuation as floodwaters from the Harding River rose to the lower
steps of the Police Station. Parts of the Wickham High School were
severely damaged and two buildings and a boat were destroyed in
the Cossack/Point Samson area. The Dampier Yacht Club was unroofed.
|
|
|
183 (Dampier)
211 (Mardie)
|
Orson crossed the coast near Cape Preston, 56 km west of
Dampier having an estimated pressure of 920 hPa. Orson caused
a storm surge of 3.1 m at Dampier but fortunately it crossed near
the time of low tide. Wave action did cause significant erosion
of sea walls at Dampier Port. Although weakening, Orson caused
widespread structural damage at Pannawonica. The total damage cost
was estimated to be in excess of $20 million in addition to the
substantial cost to offshore oil and gas infrastructure. Several
Indonesian fishing vessels were reported sunk near Ashmore Island
with at least four lives lost.
|
|
John, 15 Dec. 1999
|
210 Cape Lambert
|
John crossed the coast to the east of Roebourne
in the vicinity of Whim Creek where the hotel was extensively damaged.
Cape Lambert averaged 150 km/h winds for five hours, but fortunately
damage was of a minor nature in Karratha, Dampier and Roebourne. Rainfall
exceeded 300 mm along a strip on its track from Sherlock station to
Wittenoom. |
|
|
154 (Mardie)
|
Monty passed over Mardie station to the west
of Dampier after passing near Barrow and Varanus Islands. Although
little wind damage was recorded, widespread rainfall caused significant
flooding. Two people were rescued from the roof of the Yarraloola
homestead on the Robe River and the town of Pannawonica was cut-off.
The bridge over the Maitland River on the Northwest coastal highway
was destroyed. Monty also caused substantial economic losses
to the offshore oil and gas industry. |
| Clare,
9/10 January 2006 |
143 (Karratha)
131 (Roebourne)
|
Clare crossed the Pilbara coast between Dampier
and Mardie after midnight early on Monday 9 January. Dampier experienced
very destructive winds for a period Monday evening as the eye wall
passed over the town. Karratha narrowly escaped the eye wall but still
experienced destructive winds (category 2 intensity) for over seven
hours and gale force winds for sixteen hours. |
| Glenda,
30 March 2006 |
128 (Karratha)
|
Glenda was a small and intense system that developed
very rapidly after moving off the northwest Kimberley coast. Glenda
reached category 5 intensity but weakened as it approached the Pilbara
coast. Although threatening to cross the coast near the populated
Dampier/Karratha region as a Category 4 system close to the time of
high tide, Glenda took a more SW course towards Onslow and weakened
before finally crossing the coast near Onslow at 10pm on 30 March
as a marginal category 3 system. Very destructive winds were recorded
on the coast at Mardie prior to crossing |
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