NZ Historic Weather Events Catalogue
July 1998 Waikato Flooding
(
1998-07-08
)
2-120 years
A prolonged period of rain brought flooding and slips to many parts of the North Island, but most particularly the Waikato. Across the Waikato, farmlands and roads were flooded and homes were evacuated. The damage totalled millions of dollars.
New Zealand
Multi Hazard
Duration: 13 days - From the 8th to the 20th of July. The first stormy period was from the 7th to the 11th, and the second one was from the 14th to the 16th.
A repetitive weather pattern established over the Tasman Sea and central New Zealand. A very warm north Tasman Sea provided the energy for the successive depressions that formed during July, bringing with them the active rainfall bands that resulted in flooding.
Between the 7th and the 11th, there was a slow-moving low pressure was over the South Island and high pressures to the east of the country, and an anticyclone 'blocking' the weather system to the east. A number of fronts moved onto the North Island only to stagnate, resulting in a persistent, moist northerly flow bringing periods of heavy rain to northern districts. Surface airflow was predominantly from the north-west. On the 14th, a small, vigorous depression in the Tasman moved south-east towards northern New Zealand, and crossed the north-east of the country overnight on the 14th/15th, bringing another period of heavy rain. On the 15th, a second depression in the north Tasman, with larger and multiple cells, moved south-east, crossing northern districts on the 16th, bringing more wet, unsettled weather.
The rain came in three main episodes. Blocking to the east of New Zealand played a major role in all three. Episode 1: A low deepened rapidly in the Tasman Sea, triggered by strong CVA. There was also very strong upper level divergence in the poleward exit region to a 180 knot south-west jet and the entrance to an anticyclonically-curved north-west jet. Very moist air was brought out of the subtropics. Episode 2: Strong north to north-west winds spread over the North Island ahead of an active cold front. A complex low lay in the Tasman Sea. The development of a small low west of Taranaki occurred beneath a strongly difluent flow and the resulting increased gradient enhanced orographic contribution to heavy rain. Episode 3: At midday on the 10th, a large baroclinic leaf rapidly developed, then spread rain back over the whole northern half of the North Island. There was also a fourth burst of heavy rain on the 14th and 15th. Another 50-60 mm of rain fell over affected areas in an easterly airstream.
North Island
Heavy Rain
at
North Island
On the 8th and 9th, the first series of storms brought heavy rain to Nelson, Taranaki, Bay of Plenty (eastern areas and Rotorua), Waikato (including Coromandel, Taupo and Tongariro), and Northland (Bay of Islands).
On the 14th, high rainfall occurred in Northland, Auckland, Coromandel, Bay of Plenty, Taupo and Hawke's Bay.
Flooding
Severe flooding occurred in Waikato, Bay of Plenty, Northland and Auckland, caused by an unusually long period of wet weather.
The further high rainfall in northern New Zealand on the 14th exacerbated flooding.
Northland
High Wind / Gust
at
Northland
In Northland, northerly gales brought down trees, damaging vehicles.
Trees were brought down in Northland, blocking roads on the 16th and 17th.
Heavy Rain
Heavy convective rain fell in Auckland and Northland on the 16th and 17th.
The rain caused surface flooding on the 16th and 17th.
Auckland
Heavy Rain
at
Auckland
Heavy convective rain fell in Auckland and Northland on the 16th and 17th.
Torrential rain led people to abandon their cars cars on the 15th.
North Shore beaches were closed due to sewerage problems.
Flooding
Properties were flooded.
Landslide
Slips closed roads on the 14th.
Slips damaged properties on the 14th.
High Wind / Gust
A shuttle bus was damaged by a falling tree on the 15th.
Heavy Rain
at
Cockle Bay
Cockle Bay, Howick, recorded 84 mm (8.4 cm) of rain in 24 hours on the 14th.
Landslide
at
Mission Bay
Tamaki Drive was closed by a slip.
Waikato
Heavy Rain
at
Waikato
Heavy rainfall was experienced throughout the Waikato region between the 8th and the 16th.
The back-to-back deluges saturated the ground so river levels were unable to return to normal between events.
On the 9th, 75-125 mm (7.5-12.5 cm) of rain fell in most locations in the Waikato.
From late on the 8th, a combination of moisture and onshore winds produced widespread heavy rainfall throughout the Waikato/Central North Island catchment.
Intense rainfall was very localised.
The events occurred in winter, meaning enhanced catchment wetness and potentially greater runoff.
The heaviest falls occurred at Taupo, Rangitoto, Coromandel/Kaimai, Hapuakohe and the Hunua Ranges, with an estimated return period of 50-100 years.
The Rangitaiki and Tongariro catchments had a return period as high as 20 years.
Rainfall affected the Waikato, Bay of Plenty, Taupo and Rangitaiki areas until the evening of the 14th, when the low had moved further south towards the Bay of Plenty. The wind subsequently turned south-east. Rainfall was enhanced by the orograhic lifting, but rainfall amounts were significantly less with the orographic sheltering in the south-easterly. Successive frontal bands meant that rivers were unable to cope with the copious amounts of water entering the catchment.
Heavy rain in the Hauraki and Matamata-Piako areas was largely concentrated in the main river systems, but had a significant effect on the ponding areas of the flood control scheme.
Flooding
Extremely high river levels were experienced on the Waikato and Waipa Rivers from the 9th to the 20th due to widespread and in places record rainfall.
A sequence of storm events over the catchments of Lake Taupo and the middle reaches of the Waikato River led to extensive and prolonged flooding downstream of Hamilton.
Inflows to the Waikato River between Taupo and Karapiro had return periods of 15-80 years.
The Waikato tributary area (between Lake Taupo and Karapiro) had return periods of 2-10 years.
The most intense rain occurred along the catchment western boundarry and caused the extremely large floods in the Mangakino and Waipapa Rivers The Mangakino and Waipapa catchments experienced record floods, nearly twice as large as any recorded in the previous 35 years.
In most cases, the second event (8th-12th July) was the most severe.
The Waipa River reached its highest level since 1958.
The already high Waikato River continued to rise on the 14th, and flooded large areas from Hamilton to Huntly. The river continued to inundate properties downstream, especially at Huntly.
State Highway 1 was reduced to one lane and closed on the 15th.
11,350 hectares of farmland was flooded.
There were three major events between the 9th and the 20th July, with a 100 year return period.
Sustained, widespread rainfall resulted in higher lake levels.
Damage was done to farmland in the Waikato District, Franklin District, Waipa District, Taupo District, Waitomo District and Otorohanga District. In the lower Waikato, nine farms were completely under water, and another 30-40 were partially affected.
In the Waikato District eight buildings were badly flooded, five houses had minor flooding and ten houses/garages had minor flooding.
In the Waikato District damage was done to pasture.
In the Waipa District one houses was flooded.
In the Waipa District damage was done to pasture.
In the Taupo District, river bank erosion occurred at Tongariro and increased erosion occurred in the gully at Rakanui Road.
In the Taupo District five houses/garages had minor flooding and one house was flooded at Turangi.
In the Waitomo District approximately 20 houses were evacuated.
In the Waitomo District one house had minor flooding.
In the Otorohanga District a water pipe was broken.
The lower Waikato System from Ngaruawahia to Mercer had peak flows with an estimated return period of 50-100 years.
Between the 16th and 17th, river levels generally declined.
The flood on the Piako and Waitoa was a one-in-20 year event in the upper catchment, down to a 5 to 10 year event in the lower reaches of the Piako and Waitoa.
The big flood of 1998 was second only to the really Big Flood of 1907.
Multi Hazard
In the Waikato District local roads were closed.
In the Franklin District State Highway 1 was closed to light traffic. Local roads were also closed.
In the Waipa District local roads were closed.
State Highway 1 was closed between Taupo and Turangi.
In the Waitomo District general ersoion and landsliding occurred.
In the Waitomo District, State Highway 3 was closed at Mahoenui and local roads were also closed.
In the Otorohanga District State Highway 31 was closed and local roads were also closed.
No State of Emergency Declarations were issued.
Transit New Zealand had damage to State Highways estimated at $14.853 million ($19,152,000 2008 dollars).
District Councils had to deal with damage to local roads, stopbanks, infrastructure and road closures.
Franklin District Council had $1.18 million ($1,520,000 2008 dollars) damage to flood protection works.
Damage costs to farmland were estimated at $1.784 million ($2,300,000 2008 dollars)
Environment Waikato had an stimated $1.683 million ($2,170,000 2008 dollars) damage to flood protection works.
The cost to Environment Waikato, District Councils, Transit New Zealand, the Department of Conservation and Huntly College totalled $25 million ($32,000,000 2008 dollars).
The estimated cost for the Waikato Region for State Highway damage was between $7-9 million ($9,000,000-$11,600,000 2008 dollars).
30 houses were evacuated.
Landslide
at
Awakino Gorge
Minor slips within Awakino Gorge caused some disruptions on State Highway 3.
Flooding
The Awakino River at SH3 had a peak flow of 282 cumecs on the 9th. Estimated return period 5 years. (Munro, 1998)
The Awakino River inundated State Highway 3.
Multi Hazard
State Highway 3 was closed due to both flooding and slips.
Flooding
at
Elstow
The Waitoa River at Mellon Road had a peak flow of 68 cumecs on the 12th. (Munro, 1998) The typical flow is 11 cumecs.
The Waitoa River at Mellon Road had a peak flow of 76 cumecs on the 12th. Return Period 15 years. (Thompson, 2001)
Heavy Rain
at
Hamilton
Hamilton recorded 191 mm (19.1 cm) of rain in seven days from the 8th to the 15th. This was 55% above normal.
Flooding
The Waikato River at Bridge Street, Hamilton, recorded a flood peak level of 16.71 m. This was 1.57m below the peak level recorded in the 1958 flood.
Community paths were closed.
The Grantham Street car park was inaccessible, and low-lying streets were inundated.
Sandbags were placed along Ann Street, the lowest residential area in the city. A wall 60m long and made of 4500 sandbags was built.
In Hamilton City, up to 16 houses/garages experienced minor flooding. Electrical problems occurred.
In Hamilton City, river bank erosion occurred and paths and reserve land was lost.
The Waikato River at Hamilton had a peak flow of 807 cumecs on the 15th. (Munro, 1998) The typical flow is 306 cumecs.
The Waikato River at Hamilton had a peak flow of 785 cumecs on the 15th. Return Period 24 years. (Thompson, 2001)
The Waikato River at Hamilton reached a peak level of 16.71 m on the 15th.
The Waikato River at Hamilton had a peak discharge of 700 cumecs due to another 158 cumecs entering the sytem between Karapiro and Hamilton.
Flooding
at
Huntly
Extensive flooding occurred when the heavily swollen Waikato River burst its banks at Huntly on the 11th.
Homes in Huntly and Ngaruawahia were flooded by the rising Waikato River on the 12th.
On the 14th, the river continued to inundate properties downstream, especially at Huntly. Huntly west homes were flooded.
Sandbagging was carried out at Huntly College.
Playing fields at Huntly College were 1.5 m under water. High-pressure pumps used on farms were brought in to drain the waters from the college, pumping out 900,000 litres per hour.
Huntly College was completely flooded, causing an estimated $1.06 million damage ($1,370,000 2008 dollars).
The Waikato River at Huntly had a peak flow of 1490 cumecs on the 15th. (Munro, 1998) The typical flow is 490 cumecs.
The Waikato River at Huntly had a peak flow of 1490 cumecs on the 16th. Return Period 70 years. (Thompson, 2001)
Huntly West Woad was closed and other roads were also flooded.
Heavy Rain
at
Kaimai Range
Kaimai recorded 370 mm (37.0 cm) of rain in seven days from the 8th to the 15th. This was 111% above normal.
Flooding
at
Karapiro
The Waikato River at Karapiro had a peak discharge of 542 cumecs on the 12th.
Flooding
at
Karangahake
The Ohinemuri River at the Gorge had a peak flow of 295 cumecs on the 15th. (Munro, 1998) The typical flow is 21 cumecs.
The Ohinemuri River at Karangahake had a peak flow of 455 cumecs on the 15th. Return Period 2 years. (Thompson, 2001)
Heavy Rain
at
Kauaeranga River
Smiths (Kauaeranga catchment) recorded 165 mm (16.5 cm) of rain in seven days from the 8th to the 15th. This was 27% above normal.
Flooding
The Kauaeranga River at Smiths had a peak flow of 353 cumecs on the 26th. (Munro, 1998) The typical flow is 11 cumecs.
Flooding
at
Kiwitahi
The Piako River at Kiwitahi had a peak flow of 72 cumecs on the 11th. (Munro, 1998) The typical flow is 4 cumecs.
Flooding
at
Kuratau
Kuratau Boat Ramp lost some of its foundations due to high lake levels.
Flooding
at
Lake Taupo
Lake Taupo reached high levels. Between the 16th and 17th, Lake Taupo swelled to a level of 357.49 m - its highest level in 40 years - due to continued high tributary inputs.
50 households were evacauted on the edge of Lake Taupo due to rising water levels.
There was foreshore flooding and ersoion at lakeside settlements due to wind and wave action, particularly the foreshore adjacent to the Taupo township. Many jetties and boat ramps were rendered unusable. Lakeshore reserves suffered erosion on 200 m of lakeshore paths, undermining a section of sewer pipes and a carpark on the northern shore.
A number of stormwater outfalls on the lake were damaged.
The total inflow for Lake Taupo for July was the biggest monthly inflow since records began in 1905.
Flooding
at
Lake Waikare
Farms fringing the lake were flooded as local private stopbanks were overtopped.
Between the 11th and the 20th, Lake Waikare increased from 5.60 m to a peak of 6.29 m (the highest level since 1958), mainy due to high inflows from the Matahuru Stream.
Approximately 1.7 km^2 of land was flooded by Lake Waikare.
Landslide
at
Mahoenui
State Highway 3 was closed after a major slip at Mahoenui.
Transit New Zealand faced an estimated $5 million ($6,400,000 2008 dollars) to repair the Mahoenui land slip.
Flooding
at
Mangahanene Stream
In the Tahunaatara and Mangahanene, the third event had the highest instantaneous peak.
Heavy Rain
at
Mangatangi
Matangitangi recorded 203 mm (20.3 cm) of rain in the 72 hours to 7.40pm on the 11th (Return Period 42 years).
Mangatangi recorded 316 mm (31.6 cm) of rain in seven days from the 8th to the 15th. This was 53% above normal.
Flooding
at
Mangatangi Stream
The Mangatangi River recorded a maximum flow of 117 cumecs.
Heavy Rain
at
Maukoro Canal
Maukoro recorded 172 mm (17.2 cm) of rain in seven days from the 8th to the 15th. This was 43% above normal.
Flooding
The Piako River at Maukoro Landing peaked on the 13th.
Heavy Rain
at
Maungakawa Hill
Maungakawa recorded 202 mm (20.2 cm) of rain in seven days from the 8th to the 15th. This was 35% above normal.
Flooding
at
Mercer
The Waikato River at Mercer had a peak flow of 1575 cumecs on the 16th. (Munro, 1998) The typical flow is 545 cumecs.
Th Waikato River at Mercer reached a peak level of 6.06 m on the 16th.
The Waikato River inundated unprotected areas of floodplain in places, including the Morrison Road basin and Mercer riverbanks.
Heavy Rain
at
Ngaroma
Ngaroma recorded 271 mm (27.1 cm) of rain in the 72 hours to 4.55pm on the 11th (Return Period 22 years).
Ngaroma recorded 188 mm (18.8 cm) of rain in 24 hours (Return Period seven years).
Ngaroma recorded 361 mm (36.1 cm) of rain in seven days from the 8th to the 15th. This was 62% above normal.
Flooding
at
Ngaruawahia
Homes in Huntly and Ngaruawahia were flooded by the rising Waikato River on the 12th.
Flood flows on the Waikato River above Ngaruawahia had the magnitude of a 20-30 year event. Flood flows below Ngaruawahia increased to a 70-100 year event.
The Waikato River at Ngaruawahia had a peak flow of 1491 cumecs on the 12th. (Munro, 1998) The typical flow is 456 cumecs.
The Waikato River at Ngaruawahia had a peak flow of 1487 cumecs on the 12th. Return Period 64 years. (Thompson, 2001)
The Waikato River at Ngaruawahia reached a peak level of 13.79 m on the 12th.
Flooding
at
Okauia
The Waihou River at Okauia had a peak flow of 180 cumecs on the 11th. (Munro, 1998) The typical flow is 33 cumecs.
Heavy Rain
at
Otewa
Otewa recorded 196 mm (19.6 cm) of rain in seven days from the 8th to the 15th. This was 26% above normal.
Flooding
The peak flow at Otewa had an estimated return period of 100 years.
Flooding
at
Otorohanga
The Waipa River at Otorohanga had a peak flow of 418 cumecs on the 10th. (Munro, 1998) The typical flow is 52 cumecs.
The Waipa River at Otorohanga had a peak flow of 445 cumecs on the 10th. Return Period 48 years. (Thompson, 2001)
Flooding
at
Paeroa
The Waihou River at Puke Bridge peaked on the 15th.
Flooding
at
Piako River
The Piako Ponding Zones were used for the first time, with significant flooding occuring in these zones. Several hundred hectares in the ponding zones were inundated, as designed.
Heavy Rain
at
The Pinnacles
The Pinnacles recorded 460 mm (46.0 cm) of rain in seven days from the 8th to the 15th. This was 6% above normal.
Landslide
at
Piopio
A woman was forced to give birth at a farmhouse south of Piopio due to road slip.
Flooding
at
Poutu Pool
The Tongariro River had a peak flow of 660 cumecs on the 9th. (Munro, 1998) There was a flow of 572 cumecs on 2nd July.
The Tongariro River at Poutu Intake had a peak flow of 840 cumecs on the 9th. Return Period 15 years. (Thompson, 2001)
Heavy Rain
at
Pukekawa
Pukekawa recorded 165 mm (16.5 cm) of rain in seven days from the 8th to the 15th. This was 10% above normal.
Flooding
at
Rangiriri
At Rangiriri Spillway, 200 cumecs of water flowed across the spillway.
The Waikato River at Rangiriri had a peak flow of 1490 cumecs on the 15th. Return Period 100 years. (Munro, 1998; Thompson, 2001) The typical flow is 507 cumecs.
The Waikato River at Rangiriri reached a peak level of 9.04 m on the 15th.
Heavy Rain
at
Rangitoto Range
In the initial stages of the flood, heavy rainfall in the Rangitoto Ranges contibuted much of the water.
Flooding
at
Red Hut Pool
At Red Hut Pool, south of Turangi, a fishing bach subsided into the river and was completely demolished.
Flooding
at
Tahuna
The Piako River at P-T Road had a peak flow of 168 cumecs on the 12th. (Munro, 1998) The typical flow is 17 cumecs.
The Piako River at P-T Road had a peak flow of 170 cumecs on the 12th. Return Period 8 years. (Thompson, 2001)
Flooding
at
Tahunaatara Stream
In the Tahunaatara and Mangahanene, the third event had the highest instantaneous peak.
Flooding
at
Taupo
The Five Mile Bay and Waitahanui sewerage system was affected. Many septic tanks overflowed into the main system due to high lake levels.
Flooding
at
Tauranga-Taupo River
The Tauranga-Taupo had a peak flow of 218 cumecs on the 10th. Estimated return period 20 years. (Munro, 1998) The tyical flow is 13 cumecs, and there was a flow of 204 cumecs on 2nd July.
The Tauranga-Taupo River had a peak flow of 250 cumecs on the 10th. Return Period 23 years. (Thompson, 2001)
Heavy Rain
at
Te Aroha
Te Aroha recorded 150 mm (15.0 cm) of rain in seven days from the 8th to the 15th.
Flooding
The Waihou River at Te Aroha had a peak flow of 190 cumecs on the 16th. (Munro, 1998) The typical flow is 53 cumecs.
The Waihou River at Te Aroha had a peak flow of 206 cumecs on the 16th. Return Period 3 years. (Thompson, 2001)
Heavy Rain
at
Te Kuiti
Te Kuiti recorded 260 mm (26.0 cm) of rain in seven days from the 8th to the 15th. This was 53% above normal.
Flooding
The Te Kuiti gauge recorded exceptional returns of 33 years at three days, 100 years at seven days and well over 100 years at 14 days.
The flooding worsened at Te Kuiti on the 9th and 10th.
Four homes were evacuated in Te Kuiti due to the flooding of Mangaokewa Stream.
The Waipa River burst its banks at Te Kuiti, flooding three house basements.
Mangakewa Stream at Te Kuiti had a peak flow of 122 cumecs on the 9th. Estimated return period 50 years. (Munro, 1998) The typical flow is 11 cumecs, and there was a flow of 87 cumecs on 2nd July.
Mangakewa Stream at Te Kuiti had a peak flow of 132 cumecs on the 10th. Return Period 50 years. (Thompson, 2001)
Flooding
at
Thames
Heavy rain brought floods to Thames.
Heavy Rain
at
Tongariro
Parts of Tongariro recorded rainfall rates as high as 20 mm/hr (2.0 cm/hr).
Heavy Rain
at
Turangi
Turangi recorded 195 mm (19.5 cm) of rain in seven days from the 8th to the 15th. This was 30% above normal.
Flooding
Flooding worsened on the 9th and 10th, causing the evacuation of 10 homes near the Tongariro River in Turangi. Five or six houses close to the Tongariro Lodge were evacuated.
A log jam closed a bridge over the Tongariro River.
A sewage pump station had to be closed.
One room in a house at Turangi was flooded.
State Highway 1 was inundated near Turangi by flood waters from the Tauranga-Taupo River, and the road was closed for some days.
Heavy Rain
at
Waharoa
Waharoa recorded 138 mm (13.8 cm) of rain in seven days from the 8th to the 15th. This was 8% above normal.
Flooding
The Waitoa River at Waharoa had a peak flow of 25 cumecs on the 12th (Munro, 1998) The typical flow is 3 cumecs.
Flooding
at
Waihou River
Significant damage was done in the tributaries at the top of the Waihou River catchment.
Heavy Rain
at
Waitanguru
Waitanguru recorded 286 mm (28.6 cm) of rain in seven days from the 8th to the 15th.
Flooding
at
Waitoa River
The upper Waitoa River had a peak flow with an estimated return period of 20 years.
Flooding
at
Whangamarino
Farms fringing the Whangamarino wetland were flooded due to the swollen Maramarua and Whangamarino Rivers.
Heavy Rain
at
Wharekawa
Wharekawa recorded 275 mm (27.5 cm) of rain in seven days from the 8th to the 15th. This was 10% above normal.
Heavy Rain
at
Wharekiri Stream
Wharekiri recorded 250 mm (25.0 cm) of rain in seven days from the 8th to the 15th. This was 27% above normal.
Flooding
at
Whatawhata
The Waipa River at Whatawhata had a peak flow of 776 cumecs on the 13th. Estimated return period 80 years. (Munro, 1998) The typical flow is 165 cumecs.
The Waipa River at Whatawhata had a peak flow of 807 cumecs on the 13th. Return Period 27 years. (Thompson, 2001)
The Waipa River at Whatawhata reached a peak level of 19.56 m on the 13th.
Bay of Plenty
Flooding
at
Bay of Plenty
Heavy rain brought floods to Bay of Plenty.
Heavy Rain
at
Orouamananui Ranger Base
Ranger Station recorded 326 mm (32.6 cm) of rain in 48 hours (Return Period 80 years).
Ranger Station recorded 391 mm (39.1 cm) of rain in 72 hours (Return Period 120 years).
The rainfall rate reached 60 mm/hr (6.0 cm/hr).
Heavy Rain
at
Rotorua
Rotorua recorded 389 mm (38.9 cm) of rain in the month of July.
Flooding
at
Waimana
The Waimana township was twice isolated when the Waimana River flooded twice in the space of a few days.
Waimana River level records were broken twice in the space of a few days.
Large tracts of farmland were swamped by silt and mud.
Hawke's Bay
Heavy Rain
at
Hawke's Bay
High rainfall occurred in Hawke's Bay on the 14th.
Taranaki
Heavy Rain
at
Taranaki
The first series of storms on brought heavy rain to Taranaki on the 8th and 9th.
Heavy Rain
at
Kaponga
Kaponga recorded 400 mm (40.0 cm) of rain in 36 hours.
Landslide
at
New Plymouth
State Highway 3 was closed north of New Plymouth when a huge landslip occurred.
Manawatu-Wanganui
Flooding
at
Manawatu-Wanganui
The Whanganui River threatened some homes downstream.
Landslide
at
Manawatu Gorge
Manawatu Gorge (State Highway 3) was closed by a slip.
Marlborough
Heavy Rain
at
Marlborough
Marlborough Sounds experienced extreme rainfall on the 8th.
Heavy Rain
at
Picton
Picton recorded 204 mm (20.4 cm) of rain.
Tasman-Nelson
Heavy Rain
at
Tasman-Nelson
The first series of storms brought heavy rain to Nelson on the 8th and 9th.
References
- The big wet of '98, Special Flood Edition. Heading: Plains rivers cope well.
- Headline: July's weather cold, wet, windy in Rotorua.
- www.dailypost.co.nz, 2 August 2008.
- Environment Waikato. State of Emergency Declarations in the district since 1976.
- Floods'. Ministry of Civil Defence and Emergency Management. Volume 18, February 2001.
- Henderson, R.; Thompson, S. Waikato Tributary floods of July 1998.
- Major weather events in New Zealand, Floods and High Rainfall, Floods to 30 Sept 2005.
- Major weather events in New Zealand, Floods and High Rainfall to 31st May 2006.
- www.metservice.co.nz / Learning Centre/ Notable Weather Events Archive / 1998 Autumn.
- www.metservice.co.nz / Learning Centre / Notable Weather Events Archives / 1998 Winter / 8-18 July 1998.
- www.metservice.co.nz / Learning Center / Notable Weather Events Archies / 1998 Winter / A prolonged wet period over the North Island.
- Munro, A. J. (1998). The Waikato regional flood event of 9-20 July 1998. The Australian Journal of Disaster and Trauma Studies, 1998 (2).
- Munro, A.J. (1998). The Waikato regional flood event of 9-20 July 1998. Water and Wastes in NZ. 1998. p 26-32.
- Munro, A.J.; Chapman, M.G. (1998). Waikato Regional Flood Event of 9-20 July 1998. Environment Waikato Technical Report 1998/15.
- New Zealand Meteorological Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Thompson, L. (2001). The 'Big One" of "98, Tephra, February 2001, 16-21.
- Headline: Flood strands mother on farm as baby born.
- The Waikato Times, 10 July 1998.
- Headline: Battle of the sandbags.
- The Waikato Times, 15 July 1998.
- Headline: High pressure pumps draining Huntly College.
- The Waikato Times, 17 July 1998.
July 1998 Waikato Flooding
(
1998-07-08
)
2-120 years
A prolonged period of rain brought flooding and slips to many parts of the North Island, but most particularly the Waikato. Across the Waikato, farmlands and roads were flooded and homes were evacuated. The damage totalled millions of dollars.
New Zealand
Multi Hazard
Duration: 13 days - From the 8th to the 20th of July. The first stormy period was from the 7th to the 11th, and the second one was from the 14th to the 16th.
A repetitive weather pattern established over the Tasman Sea and central New Zealand. A very warm north Tasman Sea provided the energy for the successive depressions that formed during July, bringing with them the active rainfall bands that resulted in flooding.
Between the 7th and the 11th, there was a slow-moving low pressure was over the South Island and high pressures to the east of the country, and an anticyclone 'blocking' the weather system to the east. A number of fronts moved onto the North Island only to stagnate, resulting in a persistent, moist northerly flow bringing periods of heavy rain to northern districts. Surface airflow was predominantly from the north-west. On the 14th, a small, vigorous depression in the Tasman moved south-east towards northern New Zealand, and crossed the north-east of the country overnight on the 14th/15th, bringing another period of heavy rain. On the 15th, a second depression in the north Tasman, with larger and multiple cells, moved south-east, crossing northern districts on the 16th, bringing more wet, unsettled weather.
The rain came in three main episodes. Blocking to the east of New Zealand played a major role in all three. Episode 1: A low deepened rapidly in the Tasman Sea, triggered by strong CVA. There was also very strong upper level divergence in the poleward exit region to a 180 knot south-west jet and the entrance to an anticyclonically-curved north-west jet. Very moist air was brought out of the subtropics. Episode 2: Strong north to north-west winds spread over the North Island ahead of an active cold front. A complex low lay in the Tasman Sea. The development of a small low west of Taranaki occurred beneath a strongly difluent flow and the resulting increased gradient enhanced orographic contribution to heavy rain. Episode 3: At midday on the 10th, a large baroclinic leaf rapidly developed, then spread rain back over the whole northern half of the North Island. There was also a fourth burst of heavy rain on the 14th and 15th. Another 50-60 mm of rain fell over affected areas in an easterly airstream.
North Island
Heavy Rain
at
North Island
On the 8th and 9th, the first series of storms brought heavy rain to Nelson, Taranaki, Bay of Plenty (eastern areas and Rotorua), Waikato (including Coromandel, Taupo and Tongariro), and Northland (Bay of Islands).
On the 14th, high rainfall occurred in Northland, Auckland, Coromandel, Bay of Plenty, Taupo and Hawke's Bay.
Flooding
Severe flooding occurred in Waikato, Bay of Plenty, Northland and Auckland, caused by an unusually long period of wet weather.
The further high rainfall in northern New Zealand on the 14th exacerbated flooding.
Northland
High Wind / Gust
at
Northland
In Northland, northerly gales brought down trees, damaging vehicles.
Trees were brought down in Northland, blocking roads on the 16th and 17th.
Heavy Rain
Heavy convective rain fell in Auckland and Northland on the 16th and 17th.
The rain caused surface flooding on the 16th and 17th.
Auckland
Heavy Rain
at
Auckland
Heavy convective rain fell in Auckland and Northland on the 16th and 17th.
Torrential rain led people to abandon their cars cars on the 15th.
North Shore beaches were closed due to sewerage problems.
Flooding
Properties were flooded.
Landslide
Slips closed roads on the 14th.
Slips damaged properties on the 14th.
High Wind / Gust
A shuttle bus was damaged by a falling tree on the 15th.
Heavy Rain
at
Cockle Bay
Cockle Bay, Howick, recorded 84 mm (8.4 cm) of rain in 24 hours on the 14th.
Landslide
at
Mission Bay
Tamaki Drive was closed by a slip.
Waikato
Heavy Rain
at
Waikato
Heavy rainfall was experienced throughout the Waikato region between the 8th and the 16th.
The back-to-back deluges saturated the ground so river levels were unable to return to normal between events.
On the 9th, 75-125 mm (7.5-12.5 cm) of rain fell in most locations in the Waikato.
From late on the 8th, a combination of moisture and onshore winds produced widespread heavy rainfall throughout the Waikato/Central North Island catchment.
Intense rainfall was very localised.
The events occurred in winter, meaning enhanced catchment wetness and potentially greater runoff.
The heaviest falls occurred at Taupo, Rangitoto, Coromandel/Kaimai, Hapuakohe and the Hunua Ranges, with an estimated return period of 50-100 years.
The Rangitaiki and Tongariro catchments had a return period as high as 20 years.
Rainfall affected the Waikato, Bay of Plenty, Taupo and Rangitaiki areas until the evening of the 14th, when the low had moved further south towards the Bay of Plenty. The wind subsequently turned south-east. Rainfall was enhanced by the orograhic lifting, but rainfall amounts were significantly less with the orographic sheltering in the south-easterly. Successive frontal bands meant that rivers were unable to cope with the copious amounts of water entering the catchment.
Heavy rain in the Hauraki and Matamata-Piako areas was largely concentrated in the main river systems, but had a significant effect on the ponding areas of the flood control scheme.
Flooding
Extremely high river levels were experienced on the Waikato and Waipa Rivers from the 9th to the 20th due to widespread and in places record rainfall.
A sequence of storm events over the catchments of Lake Taupo and the middle reaches of the Waikato River led to extensive and prolonged flooding downstream of Hamilton.
Inflows to the Waikato River between Taupo and Karapiro had return periods of 15-80 years.
The Waikato tributary area (between Lake Taupo and Karapiro) had return periods of 2-10 years.
The most intense rain occurred along the catchment western boundarry and caused the extremely large floods in the Mangakino and Waipapa Rivers The Mangakino and Waipapa catchments experienced record floods, nearly twice as large as any recorded in the previous 35 years.
In most cases, the second event (8th-12th July) was the most severe.
The Waipa River reached its highest level since 1958.
The already high Waikato River continued to rise on the 14th, and flooded large areas from Hamilton to Huntly. The river continued to inundate properties downstream, especially at Huntly.
State Highway 1 was reduced to one lane and closed on the 15th.
11,350 hectares of farmland was flooded.
There were three major events between the 9th and the 20th July, with a 100 year return period.
Sustained, widespread rainfall resulted in higher lake levels.
Damage was done to farmland in the Waikato District, Franklin District, Waipa District, Taupo District, Waitomo District and Otorohanga District. In the lower Waikato, nine farms were completely under water, and another 30-40 were partially affected.
In the Waikato District eight buildings were badly flooded, five houses had minor flooding and ten houses/garages had minor flooding.
In the Waikato District damage was done to pasture.
In the Waipa District one houses was flooded.
In the Waipa District damage was done to pasture.
In the Taupo District, river bank erosion occurred at Tongariro and increased erosion occurred in the gully at Rakanui Road.
In the Taupo District five houses/garages had minor flooding and one house was flooded at Turangi.
In the Waitomo District approximately 20 houses were evacuated.
In the Waitomo District one house had minor flooding.
In the Otorohanga District a water pipe was broken.
The lower Waikato System from Ngaruawahia to Mercer had peak flows with an estimated return period of 50-100 years.
Between the 16th and 17th, river levels generally declined.
The flood on the Piako and Waitoa was a one-in-20 year event in the upper catchment, down to a 5 to 10 year event in the lower reaches of the Piako and Waitoa.
The big flood of 1998 was second only to the really Big Flood of 1907.
Multi Hazard
In the Waikato District local roads were closed.
In the Franklin District State Highway 1 was closed to light traffic. Local roads were also closed.
In the Waipa District local roads were closed.
State Highway 1 was closed between Taupo and Turangi.
In the Waitomo District general ersoion and landsliding occurred.
In the Waitomo District, State Highway 3 was closed at Mahoenui and local roads were also closed.
In the Otorohanga District State Highway 31 was closed and local roads were also closed.
No State of Emergency Declarations were issued.
Transit New Zealand had damage to State Highways estimated at $14.853 million ($19,152,000 2008 dollars).
District Councils had to deal with damage to local roads, stopbanks, infrastructure and road closures.
Franklin District Council had $1.18 million ($1,520,000 2008 dollars) damage to flood protection works.
Damage costs to farmland were estimated at $1.784 million ($2,300,000 2008 dollars)
Environment Waikato had an stimated $1.683 million ($2,170,000 2008 dollars) damage to flood protection works.
The cost to Environment Waikato, District Councils, Transit New Zealand, the Department of Conservation and Huntly College totalled $25 million ($32,000,000 2008 dollars).
The estimated cost for the Waikato Region for State Highway damage was between $7-9 million ($9,000,000-$11,600,000 2008 dollars).
30 houses were evacuated.
Landslide
at
Awakino Gorge
Minor slips within Awakino Gorge caused some disruptions on State Highway 3.
Flooding
The Awakino River at SH3 had a peak flow of 282 cumecs on the 9th. Estimated return period 5 years. (Munro, 1998)
The Awakino River inundated State Highway 3.
Multi Hazard
State Highway 3 was closed due to both flooding and slips.
Flooding
at
Elstow
The Waitoa River at Mellon Road had a peak flow of 68 cumecs on the 12th. (Munro, 1998) The typical flow is 11 cumecs.
The Waitoa River at Mellon Road had a peak flow of 76 cumecs on the 12th. Return Period 15 years. (Thompson, 2001)
Heavy Rain
at
Hamilton
Hamilton recorded 191 mm (19.1 cm) of rain in seven days from the 8th to the 15th. This was 55% above normal.
Flooding
The Waikato River at Bridge Street, Hamilton, recorded a flood peak level of 16.71 m. This was 1.57m below the peak level recorded in the 1958 flood.
Community paths were closed.
The Grantham Street car park was inaccessible, and low-lying streets were inundated.
Sandbags were placed along Ann Street, the lowest residential area in the city. A wall 60m long and made of 4500 sandbags was built.
In Hamilton City, up to 16 houses/garages experienced minor flooding. Electrical problems occurred.
In Hamilton City, river bank erosion occurred and paths and reserve land was lost.
The Waikato River at Hamilton had a peak flow of 807 cumecs on the 15th. (Munro, 1998) The typical flow is 306 cumecs.
The Waikato River at Hamilton had a peak flow of 785 cumecs on the 15th. Return Period 24 years. (Thompson, 2001)
The Waikato River at Hamilton reached a peak level of 16.71 m on the 15th.
The Waikato River at Hamilton had a peak discharge of 700 cumecs due to another 158 cumecs entering the sytem between Karapiro and Hamilton.
Flooding
at
Huntly
Extensive flooding occurred when the heavily swollen Waikato River burst its banks at Huntly on the 11th.
Homes in Huntly and Ngaruawahia were flooded by the rising Waikato River on the 12th.
On the 14th, the river continued to inundate properties downstream, especially at Huntly. Huntly west homes were flooded.
Sandbagging was carried out at Huntly College.
Playing fields at Huntly College were 1.5 m under water. High-pressure pumps used on farms were brought in to drain the waters from the college, pumping out 900,000 litres per hour.
Huntly College was completely flooded, causing an estimated $1.06 million damage ($1,370,000 2008 dollars).
The Waikato River at Huntly had a peak flow of 1490 cumecs on the 15th. (Munro, 1998) The typical flow is 490 cumecs.
The Waikato River at Huntly had a peak flow of 1490 cumecs on the 16th. Return Period 70 years. (Thompson, 2001)
Huntly West Woad was closed and other roads were also flooded.
Heavy Rain
at
Kaimai Range
Kaimai recorded 370 mm (37.0 cm) of rain in seven days from the 8th to the 15th. This was 111% above normal.
Flooding
at
Karapiro
The Waikato River at Karapiro had a peak discharge of 542 cumecs on the 12th.
Flooding
at
Karangahake
The Ohinemuri River at the Gorge had a peak flow of 295 cumecs on the 15th. (Munro, 1998) The typical flow is 21 cumecs.
The Ohinemuri River at Karangahake had a peak flow of 455 cumecs on the 15th. Return Period 2 years. (Thompson, 2001)
Heavy Rain
at
Kauaeranga River
Smiths (Kauaeranga catchment) recorded 165 mm (16.5 cm) of rain in seven days from the 8th to the 15th. This was 27% above normal.
Flooding
The Kauaeranga River at Smiths had a peak flow of 353 cumecs on the 26th. (Munro, 1998) The typical flow is 11 cumecs.
Flooding
at
Kiwitahi
The Piako River at Kiwitahi had a peak flow of 72 cumecs on the 11th. (Munro, 1998) The typical flow is 4 cumecs.
Flooding
at
Kuratau
Kuratau Boat Ramp lost some of its foundations due to high lake levels.
Flooding
at
Lake Taupo
Lake Taupo reached high levels. Between the 16th and 17th, Lake Taupo swelled to a level of 357.49 m - its highest level in 40 years - due to continued high tributary inputs.
50 households were evacauted on the edge of Lake Taupo due to rising water levels.
There was foreshore flooding and ersoion at lakeside settlements due to wind and wave action, particularly the foreshore adjacent to the Taupo township. Many jetties and boat ramps were rendered unusable. Lakeshore reserves suffered erosion on 200 m of lakeshore paths, undermining a section of sewer pipes and a carpark on the northern shore.
A number of stormwater outfalls on the lake were damaged.
The total inflow for Lake Taupo for July was the biggest monthly inflow since records began in 1905.
Flooding
at
Lake Waikare
Farms fringing the lake were flooded as local private stopbanks were overtopped.
Between the 11th and the 20th, Lake Waikare increased from 5.60 m to a peak of 6.29 m (the highest level since 1958), mainy due to high inflows from the Matahuru Stream.
Approximately 1.7 km^2 of land was flooded by Lake Waikare.
Landslide
at
Mahoenui
State Highway 3 was closed after a major slip at Mahoenui.
Transit New Zealand faced an estimated $5 million ($6,400,000 2008 dollars) to repair the Mahoenui land slip.
Flooding
at
Mangahanene Stream
In the Tahunaatara and Mangahanene, the third event had the highest instantaneous peak.
Heavy Rain
at
Mangatangi
Matangitangi recorded 203 mm (20.3 cm) of rain in the 72 hours to 7.40pm on the 11th (Return Period 42 years).
Mangatangi recorded 316 mm (31.6 cm) of rain in seven days from the 8th to the 15th. This was 53% above normal.
Flooding
at
Mangatangi Stream
The Mangatangi River recorded a maximum flow of 117 cumecs.
Heavy Rain
at
Maukoro Canal
Maukoro recorded 172 mm (17.2 cm) of rain in seven days from the 8th to the 15th. This was 43% above normal.
Flooding
The Piako River at Maukoro Landing peaked on the 13th.
Heavy Rain
at
Maungakawa Hill
Maungakawa recorded 202 mm (20.2 cm) of rain in seven days from the 8th to the 15th. This was 35% above normal.
Flooding
at
Mercer
The Waikato River at Mercer had a peak flow of 1575 cumecs on the 16th. (Munro, 1998) The typical flow is 545 cumecs.
Th Waikato River at Mercer reached a peak level of 6.06 m on the 16th.
The Waikato River inundated unprotected areas of floodplain in places, including the Morrison Road basin and Mercer riverbanks.
Heavy Rain
at
Ngaroma
Ngaroma recorded 271 mm (27.1 cm) of rain in the 72 hours to 4.55pm on the 11th (Return Period 22 years).
Ngaroma recorded 188 mm (18.8 cm) of rain in 24 hours (Return Period seven years).
Ngaroma recorded 361 mm (36.1 cm) of rain in seven days from the 8th to the 15th. This was 62% above normal.
Flooding
at
Ngaruawahia
Homes in Huntly and Ngaruawahia were flooded by the rising Waikato River on the 12th.
Flood flows on the Waikato River above Ngaruawahia had the magnitude of a 20-30 year event. Flood flows below Ngaruawahia increased to a 70-100 year event.
The Waikato River at Ngaruawahia had a peak flow of 1491 cumecs on the 12th. (Munro, 1998) The typical flow is 456 cumecs.
The Waikato River at Ngaruawahia had a peak flow of 1487 cumecs on the 12th. Return Period 64 years. (Thompson, 2001)
The Waikato River at Ngaruawahia reached a peak level of 13.79 m on the 12th.
Flooding
at
Okauia
The Waihou River at Okauia had a peak flow of 180 cumecs on the 11th. (Munro, 1998) The typical flow is 33 cumecs.
Heavy Rain
at
Otewa
Otewa recorded 196 mm (19.6 cm) of rain in seven days from the 8th to the 15th. This was 26% above normal.
Flooding
The peak flow at Otewa had an estimated return period of 100 years.
Flooding
at
Otorohanga
The Waipa River at Otorohanga had a peak flow of 418 cumecs on the 10th. (Munro, 1998) The typical flow is 52 cumecs.
The Waipa River at Otorohanga had a peak flow of 445 cumecs on the 10th. Return Period 48 years. (Thompson, 2001)
Flooding
at
Paeroa
The Waihou River at Puke Bridge peaked on the 15th.
Flooding
at
Piako River
The Piako Ponding Zones were used for the first time, with significant flooding occuring in these zones. Several hundred hectares in the ponding zones were inundated, as designed.
Heavy Rain
at
The Pinnacles
The Pinnacles recorded 460 mm (46.0 cm) of rain in seven days from the 8th to the 15th. This was 6% above normal.
Landslide
at
Piopio
A woman was forced to give birth at a farmhouse south of Piopio due to road slip.
Flooding
at
Poutu Pool
The Tongariro River had a peak flow of 660 cumecs on the 9th. (Munro, 1998) There was a flow of 572 cumecs on 2nd July.
The Tongariro River at Poutu Intake had a peak flow of 840 cumecs on the 9th. Return Period 15 years. (Thompson, 2001)
Heavy Rain
at
Pukekawa
Pukekawa recorded 165 mm (16.5 cm) of rain in seven days from the 8th to the 15th. This was 10% above normal.
Flooding
at
Rangiriri
At Rangiriri Spillway, 200 cumecs of water flowed across the spillway.
The Waikato River at Rangiriri had a peak flow of 1490 cumecs on the 15th. Return Period 100 years. (Munro, 1998; Thompson, 2001) The typical flow is 507 cumecs.
The Waikato River at Rangiriri reached a peak level of 9.04 m on the 15th.
Heavy Rain
at
Rangitoto Range
In the initial stages of the flood, heavy rainfall in the Rangitoto Ranges contibuted much of the water.
Flooding
at
Red Hut Pool
At Red Hut Pool, south of Turangi, a fishing bach subsided into the river and was completely demolished.
Flooding
at
Tahuna
The Piako River at P-T Road had a peak flow of 168 cumecs on the 12th. (Munro, 1998) The typical flow is 17 cumecs.
The Piako River at P-T Road had a peak flow of 170 cumecs on the 12th. Return Period 8 years. (Thompson, 2001)
Flooding
at
Tahunaatara Stream
In the Tahunaatara and Mangahanene, the third event had the highest instantaneous peak.
Flooding
at
Taupo
The Five Mile Bay and Waitahanui sewerage system was affected. Many septic tanks overflowed into the main system due to high lake levels.
Flooding
at
Tauranga-Taupo River
The Tauranga-Taupo had a peak flow of 218 cumecs on the 10th. Estimated return period 20 years. (Munro, 1998) The tyical flow is 13 cumecs, and there was a flow of 204 cumecs on 2nd July.
The Tauranga-Taupo River had a peak flow of 250 cumecs on the 10th. Return Period 23 years. (Thompson, 2001)
Heavy Rain
at
Te Aroha
Te Aroha recorded 150 mm (15.0 cm) of rain in seven days from the 8th to the 15th.
Flooding
The Waihou River at Te Aroha had a peak flow of 190 cumecs on the 16th. (Munro, 1998) The typical flow is 53 cumecs.
The Waihou River at Te Aroha had a peak flow of 206 cumecs on the 16th. Return Period 3 years. (Thompson, 2001)
Heavy Rain
at
Te Kuiti
Te Kuiti recorded 260 mm (26.0 cm) of rain in seven days from the 8th to the 15th. This was 53% above normal.
Flooding
The Te Kuiti gauge recorded exceptional returns of 33 years at three days, 100 years at seven days and well over 100 years at 14 days.
The flooding worsened at Te Kuiti on the 9th and 10th.
Four homes were evacuated in Te Kuiti due to the flooding of Mangaokewa Stream.
The Waipa River burst its banks at Te Kuiti, flooding three house basements.
Mangakewa Stream at Te Kuiti had a peak flow of 122 cumecs on the 9th. Estimated return period 50 years. (Munro, 1998) The typical flow is 11 cumecs, and there was a flow of 87 cumecs on 2nd July.
Mangakewa Stream at Te Kuiti had a peak flow of 132 cumecs on the 10th. Return Period 50 years. (Thompson, 2001)
Flooding
at
Thames
Heavy rain brought floods to Thames.
Heavy Rain
at
Tongariro
Parts of Tongariro recorded rainfall rates as high as 20 mm/hr (2.0 cm/hr).
Heavy Rain
at
Turangi
Turangi recorded 195 mm (19.5 cm) of rain in seven days from the 8th to the 15th. This was 30% above normal.
Flooding
Flooding worsened on the 9th and 10th, causing the evacuation of 10 homes near the Tongariro River in Turangi. Five or six houses close to the Tongariro Lodge were evacuated.
A log jam closed a bridge over the Tongariro River.
A sewage pump station had to be closed.
One room in a house at Turangi was flooded.
State Highway 1 was inundated near Turangi by flood waters from the Tauranga-Taupo River, and the road was closed for some days.
Heavy Rain
at
Waharoa
Waharoa recorded 138 mm (13.8 cm) of rain in seven days from the 8th to the 15th. This was 8% above normal.
Flooding
The Waitoa River at Waharoa had a peak flow of 25 cumecs on the 12th (Munro, 1998) The typical flow is 3 cumecs.
Flooding
at
Waihou River
Significant damage was done in the tributaries at the top of the Waihou River catchment.
Heavy Rain
at
Waitanguru
Waitanguru recorded 286 mm (28.6 cm) of rain in seven days from the 8th to the 15th.
Flooding
at
Waitoa River
The upper Waitoa River had a peak flow with an estimated return period of 20 years.
Flooding
at
Whangamarino
Farms fringing the Whangamarino wetland were flooded due to the swollen Maramarua and Whangamarino Rivers.
Heavy Rain
at
Wharekawa
Wharekawa recorded 275 mm (27.5 cm) of rain in seven days from the 8th to the 15th. This was 10% above normal.
Heavy Rain
at
Wharekiri Stream
Wharekiri recorded 250 mm (25.0 cm) of rain in seven days from the 8th to the 15th. This was 27% above normal.
Flooding
at
Whatawhata
The Waipa River at Whatawhata had a peak flow of 776 cumecs on the 13th. Estimated return period 80 years. (Munro, 1998) The typical flow is 165 cumecs.
The Waipa River at Whatawhata had a peak flow of 807 cumecs on the 13th. Return Period 27 years. (Thompson, 2001)
The Waipa River at Whatawhata reached a peak level of 19.56 m on the 13th.
Bay of Plenty
Flooding
at
Bay of Plenty
Heavy rain brought floods to Bay of Plenty.
Heavy Rain
at
Orouamananui Ranger Base
Ranger Station recorded 326 mm (32.6 cm) of rain in 48 hours (Return Period 80 years).
Ranger Station recorded 391 mm (39.1 cm) of rain in 72 hours (Return Period 120 years).
The rainfall rate reached 60 mm/hr (6.0 cm/hr).
Heavy Rain
at
Rotorua
Rotorua recorded 389 mm (38.9 cm) of rain in the month of July.
Flooding
at
Waimana
The Waimana township was twice isolated when the Waimana River flooded twice in the space of a few days.
Waimana River level records were broken twice in the space of a few days.
Large tracts of farmland were swamped by silt and mud.
Hawke's Bay
Heavy Rain
at
Hawke's Bay
High rainfall occurred in Hawke's Bay on the 14th.
Taranaki
Heavy Rain
at
Taranaki
The first series of storms on brought heavy rain to Taranaki on the 8th and 9th.
Heavy Rain
at
Kaponga
Kaponga recorded 400 mm (40.0 cm) of rain in 36 hours.
Landslide
at
New Plymouth
State Highway 3 was closed north of New Plymouth when a huge landslip occurred.
Manawatu-Wanganui
Flooding
at
Manawatu-Wanganui
The Whanganui River threatened some homes downstream.
Landslide
at
Manawatu Gorge
Manawatu Gorge (State Highway 3) was closed by a slip.
Marlborough
Heavy Rain
at
Marlborough
Marlborough Sounds experienced extreme rainfall on the 8th.
Heavy Rain
at
Picton
Picton recorded 204 mm (20.4 cm) of rain.
Tasman-Nelson
Heavy Rain
at
Tasman-Nelson
The first series of storms brought heavy rain to Nelson on the 8th and 9th.
References
- The big wet of '98, Special Flood Edition. Heading: Plains rivers cope well.
- Headline: July's weather cold, wet, windy in Rotorua.
- www.dailypost.co.nz, 2 August 2008.
- Environment Waikato. State of Emergency Declarations in the district since 1976.
- Floods'. Ministry of Civil Defence and Emergency Management. Volume 18, February 2001.
- Henderson, R.; Thompson, S. Waikato Tributary floods of July 1998.
- Major weather events in New Zealand, Floods and High Rainfall, Floods to 30 Sept 2005.
- Major weather events in New Zealand, Floods and High Rainfall to 31st May 2006.
- www.metservice.co.nz / Learning Centre/ Notable Weather Events Archive / 1998 Autumn.
- www.metservice.co.nz / Learning Centre / Notable Weather Events Archives / 1998 Winter / 8-18 July 1998.
- www.metservice.co.nz / Learning Center / Notable Weather Events Archies / 1998 Winter / A prolonged wet period over the North Island.
- Munro, A. J. (1998). The Waikato regional flood event of 9-20 July 1998. The Australian Journal of Disaster and Trauma Studies, 1998 (2).
- Munro, A.J. (1998). The Waikato regional flood event of 9-20 July 1998. Water and Wastes in NZ. 1998. p 26-32.
- Munro, A.J.; Chapman, M.G. (1998). Waikato Regional Flood Event of 9-20 July 1998. Environment Waikato Technical Report 1998/15.
- New Zealand Meteorological Service. (2008). Meteorology of Extreme Rainfalls in New Zealand (Mark Pascoe, Ed.).
- Thompson, L. (2001). The 'Big One" of "98, Tephra, February 2001, 16-21.
- Headline: Flood strands mother on farm as baby born.
- The Waikato Times, 10 July 1998.
- Headline: Battle of the sandbags.
- The Waikato Times, 15 July 1998.
- Headline: High pressure pumps draining Huntly College.
- The Waikato Times, 17 July 1998.