NZ Historic Weather Events Catalogue
December 1976 Wellington Flooding
(
1976-12-20
)
100 years
Flooding in the Wellington and Hutt Valley area resulted from extremely heavy though localized rainfall. Over 100 families were evacuated from this area and landslides were prevalent. A boy died after a landslide crushed the building he was in in Crofton Downs.
New Zealand
Multi Hazard
at
New Zealand
Duration: 4 days - From the 20th to the 23rd of December.
An area of low pressure covered New Zealand, with centres of lowest pressure to the west of Northland and to the east Marlborough.
Taranaki
High Wind / Gust
at
East Egmont
East Egmont (with an elevation of 1037 m) experienced wind gusts of up to 100 knots (185 km/hr) with a direction (dgrees true) of 350 on the 19th of December.
High Wind / Gust
at
New Plymouth
The storm caused minor damage.
The storm brought down electricity and telephone lines and many trees.
Winds gusted to 75 mph (121 km/hr).
Three men had to be rescued from a yacht.
High Wind / Gust
at
Waitara
The storm damaged at least half the apple trees in a Waitara Orchard. It may have cost the owner thousands.
Wellington
Heavy Rain
at
Wellington
Flooding in the Wellington and Hutt Valley area resulted from extremely heavy though localized rainfall.
There was a convergence line, extending from hills west of Wellington City and up Hutt Valley, between weak southeasterlies and weak northwesterlies. Contributing factors were high instability and considerable upper-level moisture. During the period of intense rainfall, winds through a deep layer of atmosphere (2-10 km) above the convergence line appeared to have been northeasterly in direction and quite light in strength. This northeasterly, containing high level of moisture, overran cooler and denser southerly air below. The rain eased when southerly winds developed sufficient strength to destroy the deep vertical structure of the convergence zone and began to move it northwards.
Daily values are inappropoiate for this storm since the heaviest rainfall occurred mostly in less than 12 hours. Rain fell between midnight of the 19th to the 20th.
The peak rainfall return period was greater than 50 years, over a 300 km^2 area. In some areas it was in excess of 100 years return period, or possibly 500 years.
Torrential rain caused rivers and streams to burst their banks.
The area affected the most was from Pinehaven and Stokes Valley through to Belmont and Maungaraki and onto Johnsonville, Ngaio and Karori.
A second centre accompanied by a large and active thunderstorm, moved near Paekakariki to the eastern side of Palliser Bay.
Flooding
A similar occurrence to this event in the Wellington region was on 26 December 1939.
Ngaio Gorge and Ngauranga Gorge roads were closed.
Preceeding the rain, Wellington area had experienced a period of relatively dry though cold weather.
Cars and trucks were washed away.
Over 100 families were evacuated.
Paddocks were flooded and farmers desperately tried to save their sheep.
Train services ceased and buses were held up.
All road access between Wellington and Hutt Valley was cut. Heavy flooding at Kaiwharawhara and Ngauranga Gorge cut Wellington off from the rest of the North Island.
It was estimated that there had been 162 hectares of land eroded by the floods.
The Earthquake and War Damage Comission estimated total damage for the flood was $30,000,000 ($205,210,000 2009 dollars). As of 1995 it was New Zealands most expensive flood.
Insurance claims totalled were $40,920,000 in 1991 ($60,643,000 2009 dollars).
Insurance industry payouts reached $6,200,000 in 1976 ($42,410,000 2009 dollars).
Landslide
There were many slips which pushed houses off foundations, destroyed some houses and cars and caused power failures.
There was a large amount of ground slope failure and mud flows. It was estimated that there were up to 925 slips in the area.
Major damage was caused by the flood and large amount of ground slope failure and mud flows.
Heavy Rain
at
Avalon
Avalon recorded 153 mm (15.3 cm) of rain in 24 hours.
Landslide
at
Crofton Downs
A three and half years old boy was crushed in a building by a landslide in Crofton Downs.
Heavy Rain
at
Hutt Valley
Many Hutt Valley rain gauge sites recorded 150-175 mm (15.0-17.5 cm) of rain (which has an annual recurrance interval of over 100 years).
It was estimated that some areas of Hutt Valley recorded up to 300 mm (30.0 cm) of rain in 24 hours.
Heavy rain began falling over the Hutt Valley at about 4am on the 20th. The rain producing cloud drifted slowly in a SW direction with the really heavy rain falling along a line running from above Pinehaven to the south of Karori. The downpour continued until about 2pm on the 20th in Pinehaven and 4pm in Wellington after which time it began to ease. Two torrential periods of rain occurred within this ten hour period, the first three hour period to 7am producing 100 mm over the Pinehaven, Stokes Valley, Taita, Avalon and Belmont areas. Then from 9am to 12pm 100 mm fell again.
Flooding
Several houses in Hutt Valley were demolished by flood waters.
Several people had to be rescued from extremely dangerous situations.
Emergency services including police, traffic officers, fire service, ambulance service, army, civil defence volunteers were stretched to capacity.
Several houses in Hutt Valley were demolished by flood water and mud.
The Hutt River flooded its banks at 11am on the 20th.
Heavy Rain
at
Karori
Karori Reservoir recorded 156 mm (15.6 cm) of rain in 24 hours.
Heavy Rain
at
Kelburn
Kelburn recorded 153 mm (15.3 cm) of rain in 24 hours.
Heavy Rain
at
Lower Hutt
Lower Hutt recorded 264 mm (26.4 cm) of rain in 24 hours.
Flooding
A Civil Defence Emergency was declared in Lower Hutt at 3:00pm on the 20th to 3:00pm on the 21st.
43 families (approx. 172 people) were evacuated from Lower Hutt.
Flooding
at
Petone
The industrial area was flooded to a depth of over one metre.
Cars were picked up and tossed around in the raging torrent.
The Petone area was the worst affected area.
The road and railway north of Wellington were cut at Petone.
Workers scrambled onto the roofs of factories awaiting rescue. More than 40 people were rescued off one Petone factory roof alone.
Flooding
at
Pinehaven
A second Civil Defence Emergency was declared in Pinehaven in Upper Hutt at 4:30pm on the 22nd to 12:00pm on the 23rd.
22 families (approx. 88 people) were evacuated from Pinehaven.
Stokes Valley and Pinehaven were declared disaster zones. Houses began to tumble from their foundations and cars and vans were swept away in raging torrents.
Flooding
at
Porirua
Kenepuru Stream burst its banks.
Heavy Rain
at
Silverstream
Silverstream recorded 118 mm (11.8 cm) of rain in 24 hours.
Flooding
at
Stokes Valley
Three houses in Stokes Valley crashed down a huge bank.
45 people were evacuated from Stokes Valley.
Heavy Rain
at
Taita
Taita recorded 230 mm (23.0 cm) of rain in eight hours (which has a return period of well over 150 years).
Flooding
at
Upper Hutt
A Civil Defence Emergency was declared in Upper Hutt at 11:25am on the 20th to 12:00pm on the 21st.
Heavy Rain
at
Wainuiomata
Wainuiomata recorded 125 mm (12.5 cm) of rain in 24 hours.
Heavy Rain
at
Wallaceville
Wallaceville recorded 114 mm (11.4 cm) of rain in 24 hours.
Flooding
at
Wellington City
Lambton Quay had 30 cm of water covering the road.
Transport into or out of Wellington was completely cut off.
There was no Civil Defence Declaration in Wellington. The mayor maintained that emergency services were coping adequately, although many felt a state of emergency should have been declared as soon as Wellington had become isolated by the flood.
References
- Boon, Kevin (1995). Events in New Zealand History: The Wellington Flood.
- Headline: Civil Defence Declarations since 1 January 1963.
- Declared Civil Defence Emergencies,
- Grayland, E.C. (1978). More New Zealand Disasters.
- Hessell, J.W.D, Holloway, R.H.F, Knowles, D.G., Roberts, J.L. Scientific, Economic and Social Reviews of Natural Hazards in New Zealand, New Zealand National Commission For UNESCO, Wellington, 1984
- Insurance Councils, The Cost of Weather Loses, Claims History (Updated 2004)
- Major weather events in New Zealand, FLOODS and HIGH RAINFALL to 31st May 2006
- New Zealand Meteorological Service, Technicial Information Circular No.191, Extreme Wind Gusts
- NZ Met Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Pictures: Hutchins, Graham. (2006). High Water: Floods in New Zealand.
- Headline: Rescuers Rescued As Heavy Winds Lashed Port Taranaki.
- The Evening Post, December 20 1976.
- Headline: Torrential Rain Brings Flood Havoc.
- The Evening Post, December 20 1976.
- Tomlinson, A.I., and Dyke, A.W., (1977). The Wellington and Hutt Valley Flood of 20 December 1976. New Zealand Meteorological Service, Technical Information Circular No.154
- Tomlinson, A.I; Dyke, A.W (1977) New Zealand Meteorological Service, Technical Information Circular No. 154, The Wellington and Hutt Valley Flood of 20 December 1976, Wellington.7p.
- WASCO 33 (1982). Flood Control in New Zealand. Water and Soil Division Ministry of Works and Development.
- Wellington Regional Water Board (1977). Report on Storm of 20 Decmber, 1976.
December 1976 Wellington Flooding
(
1976-12-20
)
100 years
Flooding in the Wellington and Hutt Valley area resulted from extremely heavy though localized rainfall. Over 100 families were evacuated from this area and landslides were prevalent. A boy died after a landslide crushed the building he was in in Crofton Downs.
New Zealand
Multi Hazard
at
New Zealand
Duration: 4 days - From the 20th to the 23rd of December.
An area of low pressure covered New Zealand, with centres of lowest pressure to the west of Northland and to the east Marlborough.
Taranaki
High Wind / Gust
at
East Egmont
East Egmont (with an elevation of 1037 m) experienced wind gusts of up to 100 knots (185 km/hr) with a direction (dgrees true) of 350 on the 19th of December.
High Wind / Gust
at
New Plymouth
The storm caused minor damage.
The storm brought down electricity and telephone lines and many trees.
Winds gusted to 75 mph (121 km/hr).
Three men had to be rescued from a yacht.
High Wind / Gust
at
Waitara
The storm damaged at least half the apple trees in a Waitara Orchard. It may have cost the owner thousands.
Wellington
Heavy Rain
at
Wellington
Flooding in the Wellington and Hutt Valley area resulted from extremely heavy though localized rainfall.
There was a convergence line, extending from hills west of Wellington City and up Hutt Valley, between weak southeasterlies and weak northwesterlies. Contributing factors were high instability and considerable upper-level moisture. During the period of intense rainfall, winds through a deep layer of atmosphere (2-10 km) above the convergence line appeared to have been northeasterly in direction and quite light in strength. This northeasterly, containing high level of moisture, overran cooler and denser southerly air below. The rain eased when southerly winds developed sufficient strength to destroy the deep vertical structure of the convergence zone and began to move it northwards.
Daily values are inappropoiate for this storm since the heaviest rainfall occurred mostly in less than 12 hours. Rain fell between midnight of the 19th to the 20th.
The peak rainfall return period was greater than 50 years, over a 300 km^2 area. In some areas it was in excess of 100 years return period, or possibly 500 years.
Torrential rain caused rivers and streams to burst their banks.
The area affected the most was from Pinehaven and Stokes Valley through to Belmont and Maungaraki and onto Johnsonville, Ngaio and Karori.
A second centre accompanied by a large and active thunderstorm, moved near Paekakariki to the eastern side of Palliser Bay.
Flooding
A similar occurrence to this event in the Wellington region was on 26 December 1939.
Ngaio Gorge and Ngauranga Gorge roads were closed.
Preceeding the rain, Wellington area had experienced a period of relatively dry though cold weather.
Cars and trucks were washed away.
Over 100 families were evacuated.
Paddocks were flooded and farmers desperately tried to save their sheep.
Train services ceased and buses were held up.
All road access between Wellington and Hutt Valley was cut. Heavy flooding at Kaiwharawhara and Ngauranga Gorge cut Wellington off from the rest of the North Island.
It was estimated that there had been 162 hectares of land eroded by the floods.
The Earthquake and War Damage Comission estimated total damage for the flood was $30,000,000 ($205,210,000 2009 dollars). As of 1995 it was New Zealands most expensive flood.
Insurance claims totalled were $40,920,000 in 1991 ($60,643,000 2009 dollars).
Insurance industry payouts reached $6,200,000 in 1976 ($42,410,000 2009 dollars).
Landslide
There were many slips which pushed houses off foundations, destroyed some houses and cars and caused power failures.
There was a large amount of ground slope failure and mud flows. It was estimated that there were up to 925 slips in the area.
Major damage was caused by the flood and large amount of ground slope failure and mud flows.
Heavy Rain
at
Avalon
Avalon recorded 153 mm (15.3 cm) of rain in 24 hours.
Landslide
at
Crofton Downs
A three and half years old boy was crushed in a building by a landslide in Crofton Downs.
Heavy Rain
at
Hutt Valley
Many Hutt Valley rain gauge sites recorded 150-175 mm (15.0-17.5 cm) of rain (which has an annual recurrance interval of over 100 years).
It was estimated that some areas of Hutt Valley recorded up to 300 mm (30.0 cm) of rain in 24 hours.
Heavy rain began falling over the Hutt Valley at about 4am on the 20th. The rain producing cloud drifted slowly in a SW direction with the really heavy rain falling along a line running from above Pinehaven to the south of Karori. The downpour continued until about 2pm on the 20th in Pinehaven and 4pm in Wellington after which time it began to ease. Two torrential periods of rain occurred within this ten hour period, the first three hour period to 7am producing 100 mm over the Pinehaven, Stokes Valley, Taita, Avalon and Belmont areas. Then from 9am to 12pm 100 mm fell again.
Flooding
Several houses in Hutt Valley were demolished by flood waters.
Several people had to be rescued from extremely dangerous situations.
Emergency services including police, traffic officers, fire service, ambulance service, army, civil defence volunteers were stretched to capacity.
Several houses in Hutt Valley were demolished by flood water and mud.
The Hutt River flooded its banks at 11am on the 20th.
Heavy Rain
at
Karori
Karori Reservoir recorded 156 mm (15.6 cm) of rain in 24 hours.
Heavy Rain
at
Kelburn
Kelburn recorded 153 mm (15.3 cm) of rain in 24 hours.
Heavy Rain
at
Lower Hutt
Lower Hutt recorded 264 mm (26.4 cm) of rain in 24 hours.
Flooding
A Civil Defence Emergency was declared in Lower Hutt at 3:00pm on the 20th to 3:00pm on the 21st.
43 families (approx. 172 people) were evacuated from Lower Hutt.
Flooding
at
Petone
The industrial area was flooded to a depth of over one metre.
Cars were picked up and tossed around in the raging torrent.
The Petone area was the worst affected area.
The road and railway north of Wellington were cut at Petone.
Workers scrambled onto the roofs of factories awaiting rescue. More than 40 people were rescued off one Petone factory roof alone.
Flooding
at
Pinehaven
A second Civil Defence Emergency was declared in Pinehaven in Upper Hutt at 4:30pm on the 22nd to 12:00pm on the 23rd.
22 families (approx. 88 people) were evacuated from Pinehaven.
Stokes Valley and Pinehaven were declared disaster zones. Houses began to tumble from their foundations and cars and vans were swept away in raging torrents.
Flooding
at
Porirua
Kenepuru Stream burst its banks.
Heavy Rain
at
Silverstream
Silverstream recorded 118 mm (11.8 cm) of rain in 24 hours.
Flooding
at
Stokes Valley
Three houses in Stokes Valley crashed down a huge bank.
45 people were evacuated from Stokes Valley.
Heavy Rain
at
Taita
Taita recorded 230 mm (23.0 cm) of rain in eight hours (which has a return period of well over 150 years).
Flooding
at
Upper Hutt
A Civil Defence Emergency was declared in Upper Hutt at 11:25am on the 20th to 12:00pm on the 21st.
Heavy Rain
at
Wainuiomata
Wainuiomata recorded 125 mm (12.5 cm) of rain in 24 hours.
Heavy Rain
at
Wallaceville
Wallaceville recorded 114 mm (11.4 cm) of rain in 24 hours.
Flooding
at
Wellington City
Lambton Quay had 30 cm of water covering the road.
Transport into or out of Wellington was completely cut off.
There was no Civil Defence Declaration in Wellington. The mayor maintained that emergency services were coping adequately, although many felt a state of emergency should have been declared as soon as Wellington had become isolated by the flood.
References
- Boon, Kevin (1995). Events in New Zealand History: The Wellington Flood.
- Headline: Civil Defence Declarations since 1 January 1963.
- Declared Civil Defence Emergencies,
- Grayland, E.C. (1978). More New Zealand Disasters.
- Hessell, J.W.D, Holloway, R.H.F, Knowles, D.G., Roberts, J.L. Scientific, Economic and Social Reviews of Natural Hazards in New Zealand, New Zealand National Commission For UNESCO, Wellington, 1984
- Insurance Councils, The Cost of Weather Loses, Claims History (Updated 2004)
- Major weather events in New Zealand, FLOODS and HIGH RAINFALL to 31st May 2006
- New Zealand Meteorological Service, Technicial Information Circular No.191, Extreme Wind Gusts
- NZ Met Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Pictures: Hutchins, Graham. (2006). High Water: Floods in New Zealand.
- Headline: Rescuers Rescued As Heavy Winds Lashed Port Taranaki.
- The Evening Post, December 20 1976.
- Headline: Torrential Rain Brings Flood Havoc.
- The Evening Post, December 20 1976.
- Tomlinson, A.I., and Dyke, A.W., (1977). The Wellington and Hutt Valley Flood of 20 December 1976. New Zealand Meteorological Service, Technical Information Circular No.154
- Tomlinson, A.I; Dyke, A.W (1977) New Zealand Meteorological Service, Technical Information Circular No. 154, The Wellington and Hutt Valley Flood of 20 December 1976, Wellington.7p.
- WASCO 33 (1982). Flood Control in New Zealand. Water and Soil Division Ministry of Works and Development.
- Wellington Regional Water Board (1977). Report on Storm of 20 Decmber, 1976.