NZ Historic Weather Events Catalogue

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May 1950 Upper South Island Flooding ( 1950-05-25 )

The torrential rain brought the rivers on both sides of the Alps into high flood.

South Island

Multi HazardMulti Hazard at South Island
Duration:   3  days - There was torrential rain and flooding in the West Coast from the 25th to the 27th of May.
Comments:

CommentThe heavy rain brought rivers on both sides of the Alps into high flood.

Tasman-Nelson

FloodingFlooding at Lake Rotoroa
Map Location: -41.79466 172.59414
Comments:

Peak DischargeLake Rotoroa outfall had a peak discharge of 3900 cusecs (110 cumecs).

FloodingFlooding at Murchison
Map Location: -41.804373 172.328619
Comments:

Physical CharacteristicMurchison recorded 2.98 in (7.57cm) of rain in 24 hours.

West Coast

FloodingFlooding at West Coast
Comments:

Affected LifelineMany bridges were swept away.

ImpactHouses were flooded.

Affected LifelineRoads and railways were blocked by slips and washouts.

Affected LifelineTelephone and telegraph lines were down.

Damage CostThe repairs to bridges cost thousands of pounds to repair.

Affected LifelineA 150 ft (45.7 m) gap was torn in the Blackball combined rail and road bridge.

Affected LifelineThe whole of Westland was isolated with radio the only means of communication.

CommentRivers in south Westland were in very high flood, some reaching record peaks.

DamageThe damage to highways was widespread and severe.

CommentIn the Buller area, the rivers were very high.

Damage CostThe cost of damage due to floods was £150,000 ($9,292,800 2009 dollars).

Stock DamageThere were considerable stock losses.

Damage CostGrey county roads suffered damage totalling £1527 ($94,600 2009 dollars).

Damage CostInangahua county roads suffered damage totalling £3455 ($214,000 2009 dollars).

FloodingFlooding at Buller River
Map Location: -41.83432 171.68813
Comments:

Physical CharacteristicUsing slope area measurement, Buller River had a discharge of 437,000 cusecs (12,374 cumecs). This flood was not as big at Westport as the flood of 1925. The catchment area was 2282 sq miles (5910 km^2).

Heavy RainHeavy Rain at Greymouth
Map Location: -42.451212 171.206779
Comments:

Physical CharacteristicGreymouth recorded 2.84 in (7.21 cm) of rain in 24 hours.

Physical CharacteristicGreymouth recorded 7.08 in (17.98 cm) of rain in four days.

FloodingFlooding
Comments:

CommentGrey River ran very high. At its peak it was level with the top of the wharf.

ImpactFloodwaters were backed up in all low-lying streets and invaded shops and homes.

ImpactMost of the business area was inundated by water.

FloodingFlooding at Haast
Map Location: -43.88022 169.040221
Comments:

Physical CharacteristicHaast and Arawhata Rivers rose approximately 2 ft (0.61 m) above the highest previous records.

Peak DischargeHaast River had an estimated peak discharge of 257,000 cusecs (7277 cumecs).

CommentHaast River overtopped its banks.

Heavy RainHeavy Rain at Hokitika
Map Location: -42.717176 170.960959
Comments:

Physical CharacteristicHokitika recorded 4.34 in (11.02 cm) of rain in 24 hours.

Heavy RainHeavy Rain at Inangahua
Map Location: -41.859148 171.954076
Comments:

Physical CharacteristicInangahua recorded 7.25 in (18.42 cm) of rain in 24 hours.

FloodingFlooding at Inangahua Landing
Map Location: -41.913966 171.895911
Comments:

Peak DischargeUsing slope area measurement, Inangahua River had a peak discharge of 124,500 cusecs (3525 cumecs) at the landing bridge. The catchment area was 388 sq miles (1005 km^2).

CommentThe 1950 flood level of Inangahua River was 1 ft (0.31 m) higher than the flood of 1926 at Rotokohu and 2 ft (0.61 m) higher at Landing Bridge.

FloodingFlooding at Kumara
Map Location: -42.630541 171.188174
Comments:

Affected LifelineThe old road bridge across Taramakau River at Kumara had two gaps, 200 ft (61 m) long, torn in it.

FloodingFlooding at Maruia River
Map Location: -42.02042 172.18685
Comments:

Peak DischargeUsing slope area measurement, Maruia River had a peak discharge of 67,400 cusecs (1909 cumecs) at Higgins bridge.

Heavy RainHeavy Rain at Otira
Map Location: -42.828956 171.557257
Comments:

Physical CharacteristicOtira recorded 16.00 in (40.64 cm) of rain in 24 hours.

Physical CharacteristicOtira recorded 32.00 in (81.28 cm) of rain in four days.

CommentThere was extremely heavy rain in the Otira area.

FloodingFlooding
Comments:

Affected LifelineNumerous slips and wash outs occurred within the Otira Gorge and the road was blocked for several weeks.

Heavy RainHeavy Rain at Reefton
Map Location: -42.109955 171.867076
Comments:

Physical CharacteristicReefton recorded 10.00 in (25.4 cm) of rain in four days.

Physical CharacteristicReefton recorded 3.90 in (9.91 cm) of rain in 24 hours.

FloodingFlooding
Comments:

CasualtiesOne man died after falling through a bridge at Reefton.

Affected LifelineThe Waitahu combined bridge near Reefton, lost a complete span and 40 ft (12.2 m) of the approach.

Canterbury

FloodingFlooding at Canterbury
Comments:

CommentThere was flooding in Canterbury caused by heavy rain in the alps.

CommentThe main rivers which were affected were the Waimakariri, Rakaia and Rangitata.

Heavy RainHeavy Rain at Bealey
Map Location: -43.033326 171.629765
Comments:

Physical CharacteristicBealey recorded 6.38 in (16.21 cm) of rain in 24 hours on the 26th

Heavy RainHeavy Rain at Cass-Arthurs Pass district
Map Location: -42.905834 171.549329
Comments:

Physical CharacteristicCass-Arthurs Pass district recorded 18.00 in (45.72 cm) of rain in 24 hours.

Physical CharacteristicCass-Arthurs Pass district recorded 26.00 in (66.04 cm) of rain in three days.

CommentCass-Arthurs Pass distict was the main area of heavy rain.

Physical CharacteristicThe automatic reader at Arthurs Pass recorded 10.55 in (26.80 cm) of rain in 24 hours on the 25th.

Physical CharacteristicThe automatic reader at Arthurs Pass recorded 10.68 in (27.13 cm) of rain in 24 hours on the 26th.

Physical CharacteristicArthurs Pass recorded 11.40 in (28.96 cm) of rain in 24 hours on the 26th (manual).

FloodingFlooding
Comments:

Affected LifelineThere was severe damage to both the highway and railway in the Bealey and Arthurs Pass area. Large sections were scoured out.

Affected LifelineHalpin Creek scoured out the road and railway and approximately 100,000 cubic yards of shingle was deposited on the road.

FloodingFlooding at Harper River
Map Location: -43.21341 171.48171
Comments:

Peak DischargeHarper River peaked at 4160 cusecs (118 cumecs) at Lake Coleridge.

Heavy RainHeavy Rain at Makarora
Map Location: -44.23631 169.233253
Comments:

CommentTorrential downpour started at 5pm on the 26th and slackened the next morning.

FloodingFlooding
Comments:

ImpactOnly the head of the lake area flooded and the low-lying ground was completely flooded.

Stock DamageThere was a loss of over 2000 sheep.

Affected LifelineMakarora Station power plant was out of action.

ImpactMakarora River changed its course.

DamageThere was damage to trees and fencing.

FloodingFlooding at Rakaia River
Map Location: -42.63756 171.39125
Comments:

Physical CharacteristicRakaia River was in high flood and washed out the approaches to the railway bridges. Water was 3 ft (0.91 m) over the line.

Affected LifelineRoad traffic was suspended.

Physical CharacteristicThe river rose 10 ft (3.05 m) above normal and the river discharge was over 160,000 cusecs (4531 cumecs).

FloodingFlooding at Rangitata River
Map Location: -43.98151 171.306532
Comments:

Peak DischargeRangitata River peaked at 53,000 cusecs (1501 cumecs) at the irrigation intake.

CommentA fairly severe flash flood occurred in Rangitata River.

Crop DamageOverflows above Arundel caused serious damage to 40 acres (16 ha) of farmland and crops.

EvacueesSome houses in the vicinity of the town were evacuated.

Affected LifelineTwo miles of road was endangered.

Heavy RainHeavy Rain at The Hermitage
Map Location: -43.7319 170.08778
Comments:

Physical CharacteristicThe Hermitage recorded 11.50 in (40.64 cm) of rain in 24 hours on the 26th.

FloodingFlooding at Waiau River
Map Location: -42.65338 172.97371
Comments:

Affected LifelineWaiau River scoured out a portion of the Lewis Pass highway.

FloodingFlooding at Waimakariri River
Map Location: -43.459744 172.289962
Comments:

CommentWaimakariri River was in heavy flood.

Physical CharacteristicThe water level rise in the gorge was 11.25 ft (3.43 m).

Physical CharacteristicWaimakariri River flood discharge was estimated at 185,000 cusecs (5239 cumecs) at the traffic bridge (the previous maximum was 175,000 cusecs (4955 cumecs)).

ImpactThere was a break in the river which flooded several hundred acres between Waimakariri River and Kaiapoi River.

Property DamageApproximately 12 houses were flooded in the Stewart Gully area.

Stock DamageStock losses were small.

References

Cowie, C.A.: Attwood, A.K. (1957) Floods in New Zealand 1920-53, The Soil Conservation and Rivers Control Council, Wellington, New Zealand, p.239.
Hydrology Annual No. 5, 1957, Soil Conservation and River Control Council, Wellington, New Zealand
Hydrology Annual No.3 1955, Soil Conservation and River Control Council, Wellington, New Zealand
Headline: Disastrous Floods Head of Lake Wanaka: Serious Losses of Stock.
Otago Daily Times, 30 May 1950.
Headline: West Coast Storms: Costly Damage To Bridges, Miners Rendered Idle.
Otago Daily Times, 30 May 1950.

May 1950 Upper South Island Flooding ( 1950-05-25 )

The torrential rain brought the rivers on both sides of the Alps into high flood.

South Island

Multi HazardMulti Hazard at South Island
Duration:   3  days - There was torrential rain and flooding in the West Coast from the 25th to the 27th of May.
Comments:

CommentThe heavy rain brought rivers on both sides of the Alps into high flood.

Tasman-Nelson

FloodingFlooding at Lake Rotoroa
Map Location: -41.79466 172.59414
Comments:

Peak DischargeLake Rotoroa outfall had a peak discharge of 3900 cusecs (110 cumecs).

FloodingFlooding at Murchison
Map Location: -41.804373 172.328619
Comments:

Physical CharacteristicMurchison recorded 2.98 in (7.57cm) of rain in 24 hours.

West Coast

FloodingFlooding at West Coast
Comments:

Affected LifelineMany bridges were swept away.

ImpactHouses were flooded.

Affected LifelineRoads and railways were blocked by slips and washouts.

Affected LifelineTelephone and telegraph lines were down.

Damage CostThe repairs to bridges cost thousands of pounds to repair.

Affected LifelineA 150 ft (45.7 m) gap was torn in the Blackball combined rail and road bridge.

Affected LifelineThe whole of Westland was isolated with radio the only means of communication.

CommentRivers in south Westland were in very high flood, some reaching record peaks.

DamageThe damage to highways was widespread and severe.

CommentIn the Buller area, the rivers were very high.

Damage CostThe cost of damage due to floods was £150,000 ($9,292,800 2009 dollars).

Stock DamageThere were considerable stock losses.

Damage CostGrey county roads suffered damage totalling £1527 ($94,600 2009 dollars).

Damage CostInangahua county roads suffered damage totalling £3455 ($214,000 2009 dollars).

FloodingFlooding at Buller River
Map Location: -41.83432 171.68813
Comments:

Physical CharacteristicUsing slope area measurement, Buller River had a discharge of 437,000 cusecs (12,374 cumecs). This flood was not as big at Westport as the flood of 1925. The catchment area was 2282 sq miles (5910 km^2).

Heavy RainHeavy Rain at Greymouth
Map Location: -42.451212 171.206779
Comments:

Physical CharacteristicGreymouth recorded 2.84 in (7.21 cm) of rain in 24 hours.

Physical CharacteristicGreymouth recorded 7.08 in (17.98 cm) of rain in four days.

FloodingFlooding
Comments:

CommentGrey River ran very high. At its peak it was level with the top of the wharf.

ImpactFloodwaters were backed up in all low-lying streets and invaded shops and homes.

ImpactMost of the business area was inundated by water.

FloodingFlooding at Haast
Map Location: -43.88022 169.040221
Comments:

Physical CharacteristicHaast and Arawhata Rivers rose approximately 2 ft (0.61 m) above the highest previous records.

Peak DischargeHaast River had an estimated peak discharge of 257,000 cusecs (7277 cumecs).

CommentHaast River overtopped its banks.

Heavy RainHeavy Rain at Hokitika
Map Location: -42.717176 170.960959
Comments:

Physical CharacteristicHokitika recorded 4.34 in (11.02 cm) of rain in 24 hours.

Heavy RainHeavy Rain at Inangahua
Map Location: -41.859148 171.954076
Comments:

Physical CharacteristicInangahua recorded 7.25 in (18.42 cm) of rain in 24 hours.

FloodingFlooding at Inangahua Landing
Map Location: -41.913966 171.895911
Comments:

Peak DischargeUsing slope area measurement, Inangahua River had a peak discharge of 124,500 cusecs (3525 cumecs) at the landing bridge. The catchment area was 388 sq miles (1005 km^2).

CommentThe 1950 flood level of Inangahua River was 1 ft (0.31 m) higher than the flood of 1926 at Rotokohu and 2 ft (0.61 m) higher at Landing Bridge.

FloodingFlooding at Kumara
Map Location: -42.630541 171.188174
Comments:

Affected LifelineThe old road bridge across Taramakau River at Kumara had two gaps, 200 ft (61 m) long, torn in it.

FloodingFlooding at Maruia River
Map Location: -42.02042 172.18685
Comments:

Peak DischargeUsing slope area measurement, Maruia River had a peak discharge of 67,400 cusecs (1909 cumecs) at Higgins bridge.

Heavy RainHeavy Rain at Otira
Map Location: -42.828956 171.557257
Comments:

Physical CharacteristicOtira recorded 16.00 in (40.64 cm) of rain in 24 hours.

Physical CharacteristicOtira recorded 32.00 in (81.28 cm) of rain in four days.

CommentThere was extremely heavy rain in the Otira area.

FloodingFlooding
Comments:

Affected LifelineNumerous slips and wash outs occurred within the Otira Gorge and the road was blocked for several weeks.

Heavy RainHeavy Rain at Reefton
Map Location: -42.109955 171.867076
Comments:

Physical CharacteristicReefton recorded 10.00 in (25.4 cm) of rain in four days.

Physical CharacteristicReefton recorded 3.90 in (9.91 cm) of rain in 24 hours.

FloodingFlooding
Comments:

CasualtiesOne man died after falling through a bridge at Reefton.

Affected LifelineThe Waitahu combined bridge near Reefton, lost a complete span and 40 ft (12.2 m) of the approach.

Canterbury

FloodingFlooding at Canterbury
Comments:

CommentThere was flooding in Canterbury caused by heavy rain in the alps.

CommentThe main rivers which were affected were the Waimakariri, Rakaia and Rangitata.

Heavy RainHeavy Rain at Bealey
Map Location: -43.033326 171.629765
Comments:

Physical CharacteristicBealey recorded 6.38 in (16.21 cm) of rain in 24 hours on the 26th

Heavy RainHeavy Rain at Cass-Arthurs Pass district
Map Location: -42.905834 171.549329
Comments:

Physical CharacteristicCass-Arthurs Pass district recorded 18.00 in (45.72 cm) of rain in 24 hours.

Physical CharacteristicCass-Arthurs Pass district recorded 26.00 in (66.04 cm) of rain in three days.

CommentCass-Arthurs Pass distict was the main area of heavy rain.

Physical CharacteristicThe automatic reader at Arthurs Pass recorded 10.55 in (26.80 cm) of rain in 24 hours on the 25th.

Physical CharacteristicThe automatic reader at Arthurs Pass recorded 10.68 in (27.13 cm) of rain in 24 hours on the 26th.

Physical CharacteristicArthurs Pass recorded 11.40 in (28.96 cm) of rain in 24 hours on the 26th (manual).

FloodingFlooding
Comments:

Affected LifelineThere was severe damage to both the highway and railway in the Bealey and Arthurs Pass area. Large sections were scoured out.

Affected LifelineHalpin Creek scoured out the road and railway and approximately 100,000 cubic yards of shingle was deposited on the road.

FloodingFlooding at Harper River
Map Location: -43.21341 171.48171
Comments:

Peak DischargeHarper River peaked at 4160 cusecs (118 cumecs) at Lake Coleridge.

Heavy RainHeavy Rain at Makarora
Map Location: -44.23631 169.233253
Comments:

CommentTorrential downpour started at 5pm on the 26th and slackened the next morning.

FloodingFlooding
Comments:

ImpactOnly the head of the lake area flooded and the low-lying ground was completely flooded.

Stock DamageThere was a loss of over 2000 sheep.

Affected LifelineMakarora Station power plant was out of action.

ImpactMakarora River changed its course.

DamageThere was damage to trees and fencing.

FloodingFlooding at Rakaia River
Map Location: -42.63756 171.39125
Comments:

Physical CharacteristicRakaia River was in high flood and washed out the approaches to the railway bridges. Water was 3 ft (0.91 m) over the line.

Affected LifelineRoad traffic was suspended.

Physical CharacteristicThe river rose 10 ft (3.05 m) above normal and the river discharge was over 160,000 cusecs (4531 cumecs).

FloodingFlooding at Rangitata River
Map Location: -43.98151 171.306532
Comments:

Peak DischargeRangitata River peaked at 53,000 cusecs (1501 cumecs) at the irrigation intake.

CommentA fairly severe flash flood occurred in Rangitata River.

Crop DamageOverflows above Arundel caused serious damage to 40 acres (16 ha) of farmland and crops.

EvacueesSome houses in the vicinity of the town were evacuated.

Affected LifelineTwo miles of road was endangered.

Heavy RainHeavy Rain at The Hermitage
Map Location: -43.7319 170.08778
Comments:

Physical CharacteristicThe Hermitage recorded 11.50 in (40.64 cm) of rain in 24 hours on the 26th.

FloodingFlooding at Waiau River
Map Location: -42.65338 172.97371
Comments:

Affected LifelineWaiau River scoured out a portion of the Lewis Pass highway.

FloodingFlooding at Waimakariri River
Map Location: -43.459744 172.289962
Comments:

CommentWaimakariri River was in heavy flood.

Physical CharacteristicThe water level rise in the gorge was 11.25 ft (3.43 m).

Physical CharacteristicWaimakariri River flood discharge was estimated at 185,000 cusecs (5239 cumecs) at the traffic bridge (the previous maximum was 175,000 cusecs (4955 cumecs)).

ImpactThere was a break in the river which flooded several hundred acres between Waimakariri River and Kaiapoi River.

Property DamageApproximately 12 houses were flooded in the Stewart Gully area.

Stock DamageStock losses were small.

References

Cowie, C.A.: Attwood, A.K. (1957) Floods in New Zealand 1920-53, The Soil Conservation and Rivers Control Council, Wellington, New Zealand, p.239.
Hydrology Annual No. 5, 1957, Soil Conservation and River Control Council, Wellington, New Zealand
Hydrology Annual No.3 1955, Soil Conservation and River Control Council, Wellington, New Zealand
Headline: Disastrous Floods Head of Lake Wanaka: Serious Losses of Stock.
Otago Daily Times, 30 May 1950.
Headline: West Coast Storms: Costly Damage To Bridges, Miners Rendered Idle.
Otago Daily Times, 30 May 1950.