Tropical Cyclone Namu

Tropical cyclone Namu was one of the worst natural disasters in the Solomon Islands in recent years. Namu originated close to the north of the Solomon Islands, not far away from the equator where the frequency of development of tropical cyclone is low. Along with destructive winds and associated with heavy rainfall. After recurring, the system intensifies as it moved towards the southern islands of Vanuatu but dissipated before it could affect the group referring to Figure 1 below. For the purpose of assignment, discussion would be on the climatic condition and the effects on the physical environment of the Solomon Islands.
Figure 1. The origin and route taken by cyclone Namu in 1986 through Solomon Islands territory adapted from Australian Meteorological web site (http://australiasevereweather.com/)
In the event and progress of tropical cyclone Namu the various climatic features are visible.
It appears that Namu developed from a ‘depression of gale intensity into a hurricane within 36 hours’ Prasad (2007). The system continues to intensifies and moving at 6-7 knot with wind speed of 50-60knots in that same duration. Along with damaging winds further sustained later up to ‘157km/hrclose to the centre and lasted for three days as hurricane force’ (http://www.cyclonextreme.com/index.htm). ‘At the height of the cyclone movement in the Solomon Islands the atmospheric pressure reaching 958 hacto Pascal according to the Australian Meteorology service’ Prasad (2007). In connection with the high winds influence by cyclone Namu, very heavy rainfall is experienced. The system moved across the Solomon Islands for ‘2-3 days of extremely bad weather before moving away further southwest’ Prasad (2007).
In relation to the intense climatic condition cause by cyclone Namu the physical environment also feels the effects. It is dramatically series for the island groups of central Solomon Islands and further south. Among the victims are the small lows laying islands around Malaita and Guadalcanal. These includes islands like Sikaiana of the Malaita outer islands, Fanalei Atifical Island and Rere near Guadalcanal are badly devastated. The population are left fewer or even without shelter, vegetation is flattening down and the flying birds are on the ground. In case of artificial islands as Ngongosila the sea walls are badly damage and eroded while on the other side of Fanalei huge volume of coral are wash ashore further enhance the island building.
Eventhough Guadalcanal and Malaita are seen as larger islands of the Solomon Islands archipelagos and heavily populated. That is the route taken by cyclone Namu of series intensity. As consequence high winds, waves flooded the coastal villages destroying houses and cover village sites with gravel and stores. The land forms as a result of cyclone Namu are still seen today around coastal Malaita and Guadalcanal.
The extremely high wind speed of about ‘80 knot (hurricane)’ Prasad (2007) refer to Table 1.2 that would also determine the nature of devastation of elevated landscape non reachable by waves. There is a great disaster for rainforest for not only the two direct affected islands also elsewhere. The evidence of this destruction forests turned brown soon after the cyclone was over.
Storm Type
Pressure (mb)
Max Gust (km/h)
10-min Ave Gust (km/h)
Dvorak Rating
Effects during landfall
Tropical Depression
>= 1000

< 52
2.0

Tropical Storm
996 - 999

52 - 62
2.5

Category 1 Tropical Cyclone
986 - 995
< 125
63 - 90
3.0 - 3.5
Negligible house damage. Damage to some crops, trees and caravans.
Category 2 Tropical Cyclone
971 - 985
125 - 169
90 - 125
4.0 - 4.5
Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings.
Category 3 Tropical Cyclone
956 - 970
170 - 224
125 - 165
5.0 - 5.5
Some roof and structural damage. Some caravans destroyed. Power failures likely.
Category 4 Tropical Cyclone
930 - 955
225 - 279
165 - 225
6.0 - 7.0
Significant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airbourne debris. Widespread power failures.
Category 5 Tropical Cyclone
<= 929
> 280
> 225
7.5 - 8.0
Extremely dangerous with widespread destruction.
Table 1.2 Set of information of tropical cyclone intensity, wind speed categories with associated destruction as a result. The data adapted from Australian Meteorology service web site.
On Larger islands as Guadalcanal heavy rainfall was another problem. Because of the long days of continuous rain the catchments areas of rivers are filled. This give rise to river water level is on what river banks can hold then flat plans as of north Guadalcanal experience flooding of series nature. People are evacuated by boats refer to Figure 2.a and eroded banks Figure 2 b. Among the many substances and objects carried by flood are ranging from sediments, stones, logs and even death bodies of animals including humans. For instance on Guadalcanal alone counts up to more than one hundred deaths and missing people.
a. b. Figure 2. A demonstration of events of cyclone Namu on the Guadalcanal plane (a) huge flooding causes to be evacuated by boats in the areas of the CDC Plane. (b) Eroded riverbank of Ngalipiu River on Guadalcanal at the height of the cyclone. Photos obtain from family.webshots.com/album/361598622hWFyhe web.
In the interior and higher altitude landscape of those two most devastated islands there exists what commonly called landslide. These known to have contributed to destroy gardens, alter nature of river channels and cause road to close.