NZ Historic Weather Events Catalogue
April 1975 Tasman-Nelson and Marlborough Flooding
(
1975-04-01
)
21-50 years
A weather bomb caused flooding in Marlborough.
South Island
Multi Hazard
at
South Island
A weather "bomb” developed from a wave near Lord Howe Island. Development occurred in equatorwards entrance to a 150 kt jet, and in an area of strong vorticity advection. There was deepening of the low from 998 hPa to 968 hPa in an 18-hour period - almost two bergerons. Deepening rates of this magnitude are rarely seen in New Zealand area. A period of very strong northwest winds affected northern South Island ahead of the front, with wind strength supplemented by the rapid movement of the low, and by outflow from thunderstorms accompanying the front.
Tasman-Nelson
Multi Hazard
at
Tasman-Nelson
Weather situation that produced high rainfall was very similar to that of the flood of 1954 which was also a major event for the Cobb Reservoir.
There was minor damage.
Heavy Rain
at
Cobb Dam
Cobb Dam recorded 121 mm (12.1 cm) of rain in 17 hours.
Flooding
The heavy rain produced the largest ever peak flow into Cobb reservoir.
Heavy Rain
at
Uruwhenua
Uruwhenua recorded 198 mm (19.8 cm) of rain in 24 hours.
Marlborough
Heavy Rain
at
Marlborough
The heavy rain was associated with a depression which developed in the North Tasman Sea and moved southeastwards towards Fiordland. The significant contributing factor to the large rainfalls was the strong northwesterly surface wind.
Heavy rain began at 8:30am on the 1st of April and a 15 hour period of heavy rain followed.
Heavy Rain
at
Onamalutu
Onamalutu recorded 157 mm (15.7 cm) of rain in 24 hours (which has a return period of 25 years).
Heavy Rain
at
The Branch Homestead
The Branch recorded 127 mm (12.7 cm) of rain in 24 hours (which was a return period of 20 years).
Heavy Rain
at
The Wye
153 mm The Wye recorded 153 mm (15.3 cm) of rain.
Heavy Rain
at
Waihopai Hill
Waihopai recorded 75 mm (7.5 cm) of rain in 24 hours.
Flooding
at
Wairau River
The flow of Wairau River was similar to that of the flood of 1954.
The flow was the greatest since at least the flood of 1936.
Flood control prevented damage from the flood.
The flood had an estimated return period of 50 years.
References
- Major weather events in New Zealand, FLOODS and HIGH RAINFALL to 31st May 2006.
- NZ Met Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Pascoe, R.M. (1982). The Flood of 1 April 1975 in the Wairau River, Marlborough, New Zealand. Weather and Climate (1982) 2:17-21.
April 1975 Tasman-Nelson and Marlborough Flooding
(
1975-04-01
)
21-50 years
A weather bomb caused flooding in Marlborough.
South Island
Multi Hazard
at
South Island
A weather "bomb” developed from a wave near Lord Howe Island. Development occurred in equatorwards entrance to a 150 kt jet, and in an area of strong vorticity advection. There was deepening of the low from 998 hPa to 968 hPa in an 18-hour period - almost two bergerons. Deepening rates of this magnitude are rarely seen in New Zealand area. A period of very strong northwest winds affected northern South Island ahead of the front, with wind strength supplemented by the rapid movement of the low, and by outflow from thunderstorms accompanying the front.
Tasman-Nelson
Multi Hazard
at
Tasman-Nelson
Weather situation that produced high rainfall was very similar to that of the flood of 1954 which was also a major event for the Cobb Reservoir.
There was minor damage.
Heavy Rain
at
Cobb Dam
Cobb Dam recorded 121 mm (12.1 cm) of rain in 17 hours.
Flooding
The heavy rain produced the largest ever peak flow into Cobb reservoir.
Heavy Rain
at
Uruwhenua
Uruwhenua recorded 198 mm (19.8 cm) of rain in 24 hours.
Marlborough
Heavy Rain
at
Marlborough
The heavy rain was associated with a depression which developed in the North Tasman Sea and moved southeastwards towards Fiordland. The significant contributing factor to the large rainfalls was the strong northwesterly surface wind.
Heavy rain began at 8:30am on the 1st of April and a 15 hour period of heavy rain followed.
Heavy Rain
at
Onamalutu
Onamalutu recorded 157 mm (15.7 cm) of rain in 24 hours (which has a return period of 25 years).
Heavy Rain
at
The Branch Homestead
The Branch recorded 127 mm (12.7 cm) of rain in 24 hours (which was a return period of 20 years).
Heavy Rain
at
The Wye
153 mm The Wye recorded 153 mm (15.3 cm) of rain.
Heavy Rain
at
Waihopai Hill
Waihopai recorded 75 mm (7.5 cm) of rain in 24 hours.
Flooding
at
Wairau River
The flow of Wairau River was similar to that of the flood of 1954.
The flow was the greatest since at least the flood of 1936.
Flood control prevented damage from the flood.
The flood had an estimated return period of 50 years.
References
- Major weather events in New Zealand, FLOODS and HIGH RAINFALL to 31st May 2006.
- NZ Met Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Pascoe, R.M. (1982). The Flood of 1 April 1975 in the Wairau River, Marlborough, New Zealand. Weather and Climate (1982) 2:17-21.