# Whangaehu River

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River in Manawatū-Whanganui, New Zealand

Whangaehu River The State Highway 49 bridge at Tangiwai Etymology Māori meaning "muddy / murky harbour" Native name Whangaehu (Māori) Location Country New Zealand Region Manawatū-Whanganui Physical characteristics Source Crater lake • location Mount Ruapehu • coordinates 39°17′2″S 175°33′50″E / 39.28389°S 175.56389°E / -39.28389; 175.56389 • elevation 2,550 metres (8,370 ft) Mouth Tasman Sea • coordinates 40°2′28″S 175°6′0″E / 40.04111°S 175.10000°E / -40.04111; 175.10000 • elevation Sea level Length 161 kilometres (100 mi) Basin features Tributaries • right Wahianoa River, Mangawhero River

The **Whangaehu River** is a large river in the central [North Island](/source/North_Island) of New Zealand. Its headwaters are the crater lake of [Mount Ruapehu](/source/Mount_Ruapehu) on the [central plateau](/source/North_Island_Volcanic_Plateau), and it flows into the [Tasman Sea](/source/Tasman_Sea) eight kilometres southeast of [Whanganui](/source/Whanganui). Due to the high acidity of the water coming from the crater lake, water is not diverted from the headwaters for the [Tongariro Power Scheme](/source/Tongariro_Power_Scheme). Instead, it bypasses the Waihianoa Aqueduct via a ford.

## Length

The river flows for 161 kilometres (100 mi) southward to the [South Taranaki Bight](/source/South_Taranaki_Bight) near the settlement of [Whangaehu](/source/Whangaehu).

## Notoriety

The sudden collapse of part of the Ruapehu crater wall on 24 December 1953 led to New Zealand's worst railway accident, the [Tangiwai disaster](/source/Tangiwai_disaster). A [lahar](/source/Lahar) – a sudden surge of mud-laden water – swept down the river, significantly weakening the structure of a railway bridge at the small settlement of Tangiwai. The overnight express train between Wellington and Auckland passed over the bridge minutes later, causing it to collapse into the turbulent waters. Of the 285 people on the train, 151 were killed.

## Timeline

- 13 December 1859: The bridge was washed away.[1]

- In February 1862 [James Coutts Crawford](/source/Coutts_Crawford) was given a number of old songs and "various accounts of the taniwha, one of whom we were told overthrew the Wangaehu bridge."[2]

- 1889: flood caused by the eruptions of [Ruapehu](/source/Mount_Ruapehu).

- 1895: flood caused by the eruptions of Ruapehu.[3]

- 24 December 1953: [Tangiwai disaster](/source/Tangiwai_disaster)

- 18 March 2007: Mt Ruapehu crater lake burst releasing an estimated 1.29 billion cubic metres of water, mud, and sludge; the Ruapehu [ERLAWS](/source/ERLAWS) alarm successfully activated preventing any accidents. This [lahar](/source/Lahar) was 50% bigger than the 1953 lahar that caused the [Tangiwai disaster](/source/Tangiwai_disaster).[4][5]

## Geology

The river is often poisoned with toxic chemicals from the volcanic activity in and around [Mount Ruapehu](/source/Mount_Ruapehu). The upper part of the river begins as the meltwater from a small glacier. When hot water from the lake spills, it quickly melts the ice and snow in the glacier forming a cave-like tunnel.[3]

## Notes

1. **[^](#cite_ref-1)** ["Ruapehu and the Wangaehu River"](https://paperspast.natlib.govt.nz/newspapers/WH19020611.2.80). *[The Wanganui Herald](/source/The_Wanganui_Herald)*. Vol. XXXVI, no. 10667. 11 June 1902. p. 2. Retrieved 21 March 2022.

1. **[^](#cite_ref-2)** ["Recollections of travel in New Zealand and Australia : Crawford, James Coutts : Free Download & Streaming : Internet Archive"](https://archive.org/details/recollectionstr00coutgoog). 10 March 2001. Retrieved 23 October 2013.

1. ^ [***a***](#cite_ref-mcsaveney_3-0) [***b***](#cite_ref-mcsaveney_3-1) McSaveney, Eileen (12 June 2006). ["Historic volcanic activity"](https://teara.govt.nz/en/historic-volcanic-activity). *[Te Ara - the Encyclopedia of New Zealand](/source/Te_Ara_-_the_Encyclopedia_of_New_Zealand)*. [Ministry for Culture and Heritage](/source/Ministry_for_Culture_and_Heritage).

1. **[^](#cite_ref-wunderman_4-0)** Wunderman, R (2007). "Report on Ruapehu (New Zealand) — March 2007". *Bulletin of the Global Volcanism Network*. **32** (3). [Smithsonian Institution](/source/Smithsonian_Institution).

1. **[^](#cite_ref-becker_5-0)** Becker, JS (2017). "Organisational Response to the 2007 Ruapehu Crater Lake Dam-Break Lahar in New Zealand: Use of Communication in Creating an Effective Response". *Observing the volcano world : volcano crisis communication*. Barcelona: Springer. pp. 253–269. [ISBN](/source/ISBN_(identifier)) [978-3-319-44095-8](https://en.wikipedia.org/wiki/Special:BookSources/978-3-319-44095-8).

## External links

- Horizons Regional Council. [Whangaehu Freshwater Management Unit](https://storymaps.arcgis.com/stories/61d5503328e646e69af0869b9e6aa6f5), 2023

v t e Tongariro National Park, New Zealand Mountains Hauhungatahi Mount Ngauruhoe Pihanga Mount Ruapehu Mount Tongariro Ski fields Tukino Turoa Whakapapa skifield Walking tracks Tongariro Alpine Crossing Tongariro Northern Circuit Lakes Lake Rotopounamu Tama Lakes Rivers Manganuioteao River Mangaturuturu River Mangawhero River Tongariro River Wahianoa River Whakapapa River Whangaehu River Whanganui River Deserts Rangipo Desert Localities and buildings Erua Horopito National Park Ohakune Pokaka Whakapapa Village Chateau Tongariro Related North Island Volcanic Plateau Poutu Fault Zone Waihi Fault Zone

v t e Rangitikei District, New Zealand Seat: Marton Populated places Northern WardNR Mangamahu Mangaweka Mataroa Moawhango Ngamahanga Ohingaiti Papanui Junction Pukeokahu Taihape Taoroa Junction Utiku Central WardCR Crofton Hunterville Marton Porewa Southern WardSR Bulls Koitiata Lake Alice Parewanui Rātana Pā Santoft Turakina Whangaehu Geographic features Kaweka Forest Park Kawhatau River Lake Alice Mangawharariki River Moawhango River Rangitikei River Whangaehu River Facilities and attractions Bruce Park Scenic Reserve Lake Alice Hospital Kaimanawa Forest Park North Island Main Trunk Ruahine Forest Park Government District Council Mayor Manawatū-Whanganui Regional Council Hawke's Bay Regional Council Rangitīkei electorate Te Tai Hauāuru electorate Wanganui and Rangitikei electorate (defunct) Schools Huntley Nga Tawa Diocesan Rangitikei College Taihape Area School Turakina Māori Girls' College (closed) NR - consists of former Taihape Ward and partially northern part of former Hunterville Ward since 2019; CR - consisted of former Marton Ward, most of southern part of Hunterville Ward and partially northern part of Turakina Ward since 2019; SR - consisted of Bulls Ward and most of southern part of Turakina Ward since 2019

Authority control databases: National United States Israel

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Adapted from the Wikipedia article [Whangaehu River](https://en.wikipedia.org/wiki/Whangaehu_River) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Whangaehu_River?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.