Whangaehu River

{{Use dmy dates|date=July 2019}} {{Use New Zealand English|date=March 2024}} {{Infobox river | name = Whangaehu River | native_name ={{native name|mi|Whangaehu}} | name_other = | name_etymology = [[Māori language|Māori]] meaning "muddy / murky harbour" | nickname =  | image = TangiwaiRoadBridge1b.jpg | image_size = 300px | image_caption = The [[State Highway 49 (New Zealand)|State Highway 49]] bridge at Tangiwai | image_alt =  | map = {{Maplink|frame=yes|type=line|plain=yes|zoom=8|frame-align=center|frame-width=300|frame-height=300|stroke-color=#0000ff|stroke-width=2}} | map_size = | map_caption = | map_alt = | pushpin_map = | pushpin_map_size = | pushpin_map_caption= | pushpin_map_alt =  | subdivision_type1 = Country | subdivision_name1 = [[New Zealand]] | subdivision_type2 = Region | subdivision_name2 = [[Manawatū-Whanganui]] | subdivision_type3 = | subdivision_name3 = | subdivision_type4 = | subdivision_name4 = | subdivision_type5 = | subdivision_name5 =  | length = {{convert|161|km|mi}} | width_min = | width_avg = | width_max = | depth_min = | depth_avg = | depth_max = | discharge1_location= | discharge1_min = | discharge1_avg = | discharge1_max =  | source1 = Crater lake | source1_location = [[Mount Ruapehu]] | source1_coordinates= {{Coord|39|17|2|S|175|33|50|E|display=inline}} | source1_elevation = {{convert|2550|m|ft}} | mouth = [[Tasman Sea]] | mouth_location = | mouth_coordinates = {{coord|40|2|28|S|175|6|0|E|region:NZ-MWT_type:landmark|display=title,inline}} | mouth_elevation = [[Sea level]] | progression = | river_system = | basin_size = | basin_landmarks = | basin_population = | tributaries_left = | tributaries_right = [[Wahianoa River]], [[Mangawhero River]] | waterbodies = | waterfalls = | bridges = | ports = | custom_label = | custom_data = | extra = }}

The '''Whangaehu River''' is a large river in the central [[North Island]] of New Zealand. Its headwaters are the crater lake of [[Mount Ruapehu]] on the [[North Island Volcanic Plateau|central plateau]], and it flows into the [[Tasman Sea]] eight kilometres southeast of [[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]]. Instead, it bypasses the Waihianoa Aqueduct via a ford.

==Length== The river flows for {{convert|161|km|mi}} southward to the [[South Taranaki Bight]] near the settlement of [[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]]. A [[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.<ref>{{cite news |title=Ruapehu and the Wangaehu River |url= https://paperspast.natlib.govt.nz/newspapers/WH19020611.2.80 |access-date=21 March 2022 |work=[[The Wanganui Herald]] |volume =XXXVI |issue=10667 |date=11 June 1902 |page=2}}</ref> * In February 1862 [[Coutts Crawford|James 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."<ref>{{cite web|url=https://archive.org/details/recollectionstr00coutgoog |title=Recollections of travel in New Zealand and Australia : Crawford, James Coutts : Free Download & Streaming : Internet Archive |date=2001-03-10 |access-date=2013-10-23}}</ref> * 1889: flood caused by the eruptions of [[Mount Ruapehu|Ruapehu]]. * 1895: flood caused by the eruptions of Ruapehu.<ref name="mcsaveney">{{cite web |last1=McSaveney |first1=Eileen |title=Historic volcanic activity |url=https://teara.govt.nz/en/historic-volcanic-activity |website=[[Te Ara - the Encyclopedia of New Zealand]] |publisher=[[Ministry for Culture and Heritage]] |date=12 June 2006}}</ref> * 24 December 1953: [[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]] alarm successfully activated preventing any accidents. This [[lahar]] was 50% bigger than the 1953 lahar that caused the [[Tangiwai disaster]].<ref name="wunderman">{{cite journal |last1=Wunderman |first1=R |title=Report on Ruapehu (New Zealand) — March 2007 |journal=Bulletin of the Global Volcanism Network |date=2007 |volume=32 |issue=3 |publisher=[[Smithsonian Institution]]}}</ref><ref name="becker">{{cite book |last1=Becker |first1=JS |title=Observing the volcano world : volcano crisis communication |date=2017 |publisher=Springer |location=Barcelona |isbn=978-3-319-44095-8 |pages=253–269 |chapter=Organisational Response to the 2007 Ruapehu Crater Lake Dam-Break Lahar in New Zealand: Use of Communication in Creating an Effective Response}}</ref>

==Geology== The river is often poisoned with toxic chemicals from the volcanic activity in and around [[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.<ref name="mcsaveney" />

==Notes== {{Reflist}}

== External links ==

* Horizons Regional Council. [https://storymaps.arcgis.com/stories/61d5503328e646e69af0869b9e6aa6f5 Whangaehu Freshwater Management Unit], 2023 {{Tongariro National Park}} {{Rangitikei District}} {{Authority control}}

[[Category:Rivers of Manawatū-Whanganui]] [[Category:Tongariro National Park]]