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Wanganui River: Difference between revisions

Coordinates: 43°02′07″S 170°25′50″E / 43.0353°S 170.4305°E / -43.0353; 170.4305
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{{Short description|River in New Zealand}}
{{Short description|River in New Zealand}}
{{About||the river on North Island, formerly called the Wanganui|Whanganui River}}
{{About||the river in the North Island formerly called the Wanganui|Whanganui River}}
{{Use New Zealand English|date=April 2024}}
{{Use dmy dates|date=July 2019}}
{{Use dmy dates|date=July 2019}}
{{Infobox river
⚫
[[File:Wanganui River 03.jpg|thumb]]
| name = Wanganui River
| native_name =
⚫
| image = Wanganui River 03.jpg
| image_size =
| image_caption =
| subdivision_type1 = Country
| subdivision_name1 = New Zealand
| subdivision_type2 = Region
| subdivision_name2 = [[West Coast Region|West Coast]]
| subdivision_type3 = District
| subdivision_name3 = [[Westland District|Westland]]
| source1_location = [[Southern Alps]]
| mouth_location = [[Tasman Sea]]
| length = {{convert|55|km}}
| source1_elevation =
| mouth_elevation =
| discharge1_avg =
| basin_size =
| tributaries_left = Lambert River, Adams River, Oneone River
| tributaries_right = Smyth River
}}


The '''Wanganui River''' is in the [[West Coast, New Zealand|West Coast]] of the [[South Island]] of New Zealand. It flows northwest for {{convert|55|km|mi}} from its headwaters in the [[Southern Alps]], entering the [[Tasman Sea]] near [[Lake Ianthe]], {{convert|40|km|mi}} southwest of [[Hokitika]].
The '''Wanganui River''' is in the [[West Coast, New Zealand|West Coast]] of the [[South Island]] of New Zealand. It flows northwest for {{convert|55|km|mi}} from its headwaters in the [[Southern Alps]], entering the [[Tasman Sea]] near [[Lake Ianthe]], {{convert|40|km|mi}} southwest of [[Hokitika]].


After heavy rain in January 2013 the flooded river partially washed away the single-lane road bridge that carries {{NZlSH|6}}, closing the only through road on the West Coast.<ref>{{cite news|url=http://www.stuff.co.nz/the-press/news/8137779/Highway-closed-after-bridge-washout|title=Highway closed after bridge washout|date=3 January 2013|work=[[The Press]]|accessdate=3 January 2013}}</ref>
After heavy rain in January 2013 the flooded river partially washed away the single-lane road bridge that carries {{NZlSH|6}}, closing the only through road on the West Coast.<ref>{{cite news|url=http://www.stuff.co.nz/the-press/news/8137779/Highway-closed-after-bridge-washout|title=Highway closed after bridge washout|date=3 January 2013|work=[[The Press]]|accessdate=3 January 2013}}</ref>


Gravel buildup has gradually raised the riverbed, and in 2021 the [[West Coast Regional Council]] planned to elevate [[Stopbank|stopbanks]] by 1 m at a cost of $5.7 million to protect neighbouring farmland from flooding. Farmers protested the rates rise that would be needed to pay back this 30-year loan, and suggested the [[Department of Conservation (New Zealand)|Department of Conservation]] should contribute.<ref>{{Cite news|last=Williams|first=Lois|date=20 September 2021|title=Farmer calls out Doc over cost of flood protection|page=3|work=Hokitika Guardian}}</ref>
Gravel buildup has gradually raised the riverbed, and in 2021 the [[West Coast Regional Council]] planned to elevate [[stopbank]]s by 1 m at a cost of $5.7 million to protect neighbouring farmland from flooding. Farmers protested the rates rise that would be needed to pay back this 30-year loan, and suggested the [[Department of Conservation (New Zealand)|Department of Conservation]] should contribute.<ref>{{Cite news|last=Williams|first=Lois|date=20 September 2021|title=Farmer calls out Doc over cost of flood protection|page=3|work=Hokitika Guardian}}</ref>


In April 2023, a river engineer briefed local farmers, and outlined the history of development of stop banks on the river. In 1948, the river had a wide and natural [[braided river]] course. However, over a period of 60 years, stop banks were constructed along the original river bed to create pasture land. The result was that the river became increasing constrained, taking up only half of the area it previously occupied. The consequence is that the rate of [[aggradation]] has doubled. In the area {{Convert|7|km}} downstream of the [[State Highway 6 (New Zealand)|State Highway 6]] bridge, the river now sits above the flood plain. The location where the river broke through the stop banks earlier in 2023 was the normal river bed in the 1960's. Construction of stop banks to narrow the river channel has also increased the gradient of the river bed, and increased the velocity of water flowing against the stop banks. Climate variability is producing more intense storms, and combined with the other factors, is increasing the threat of future breaches.<ref>{{Cite web |last=McMahon |first=Brendon |date=2023-04-22 |title=Stop banks 'strangle' West Coast river over 60 years |url=https://www.rnz.co.nz/news/national/488478/stop-banks-strangle-west-coast-river-over-60-years |access-date=2023-04-23 |website=RNZ |language=en-nz}}</ref>
In March 2023, the river broke through a hole in the stopbank on the north side, and caused significant flooding damage to several farms.<ref>{{Cite web |last=McMahon |first=Brendon |date=9 March 2023 |title=Wanganui River in-flood flows onto farms after council 'failed' to heed warning |url=https://www.rnz.co.nz/news/country/485645/wanganui-river-in-flood-flows-onto-farms-after-council-failed-to-heed-warning |access-date=23 April 2023 |website=RNZ |language=en-nz}}</ref>
In April 2023, a river engineer briefed local farmers, and outlined the history of development of stop banks on the river. In 1948, the river had a wide and natural [[braided river]] course. However, over a period of 60 years, stop banks were constructed along the original river bed to create pasture land. The result was that the river became increasing constrained, taking up only half of the area it previously occupied. The consequence is that the rate of [[aggradation]] has doubled. In the area {{Convert|7|km}} downstream of the State Highway 6 bridge, the river now sits above the flood plain. The location where the river broke through the stop banks earlier in 2023 was the normal river bed in the 1960s. Construction of stop banks to narrow the river channel has also increased the gradient of the river bed, and increased the velocity of water flowing against the stop banks. Climate variability is producing more intense storms, and combined with the other factors, is increasing the threat of future breaches.<ref>{{Cite web |last=McMahon |first=Brendon |date=2023-04-22 |title=Stop banks 'strangle' West Coast river over 60 years |url=https://www.rnz.co.nz/news/national/488478/stop-banks-strangle-west-coast-river-over-60-years |access-date=2023-04-23 |website=RNZ |language=en-nz}}</ref>


==References==
==References==
{{commons category|Wanganui River}}
{{Reflist}}
{{Reflist}}


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[[Category:Westland District]]
[[Category:Westland District]]
[[Category:Rivers of the West Coast, New Zealand]]
[[Category:Rivers of the West Coast Region]]
[[Category:Rivers of New Zealand]]
[[Category:Rivers of New Zealand]]


{{WestCoastNZ-river-stub}}

Latest revision as of 22:11, 14 July 2024

For the river in the North Island formerly called the Wanganui, see Whanganui River.

Wanganui River
Map
Location
CountryNew Zealand
RegionWest Coast
DistrictWestland
Physical characteristics
Source 
 • locationSouthern Alps
Mouth 
 • location
Tasman Sea
Length55 kilometres (34 mi)
Basin features
Tributaries 
 • leftLambert River, Adams River, Oneone River
 • rightSmyth River

The Wanganui River is in the West Coast of the South Island of New Zealand. It flows northwest for 55 kilometres (34 mi) from its headwaters in the Southern Alps, entering the Tasman Sea near Lake Ianthe, 40 kilometres (25 mi) southwest of Hokitika.

After heavy rain in January 2013 the flooded river partially washed away the single-lane road bridge that carries State Highway 6, closing the only through road on the West Coast.[1]

Gravel buildup has gradually raised the riverbed, and in 2021 the West Coast Regional Council planned to elevate stopbanks by 1 m at a cost of $5.7 million to protect neighbouring farmland from flooding. Farmers protested the rates rise that would be needed to pay back this 30-year loan, and suggested the Department of Conservation should contribute.[2]

In March 2023, the river broke through a hole in the stopbank on the north side, and caused significant flooding damage to several farms.[3]

In April 2023, a river engineer briefed local farmers, and outlined the history of development of stop banks on the river. In 1948, the river had a wide and natural braided river course. However, over a period of 60 years, stop banks were constructed along the original river bed to create pasture land. The result was that the river became increasing constrained, taking up only half of the area it previously occupied. The consequence is that the rate of aggradation has doubled. In the area 7 kilometres (4.3 mi) downstream of the State Highway 6 bridge, the river now sits above the flood plain. The location where the river broke through the stop banks earlier in 2023 was the normal river bed in the 1960s. Construction of stop banks to narrow the river channel has also increased the gradient of the river bed, and increased the velocity of water flowing against the stop banks. Climate variability is producing more intense storms, and combined with the other factors, is increasing the threat of future breaches.[4]

References

[edit]
Wikimedia Commons has media related to Wanganui River.
  1. ^ "Highway closed after bridge washout". The Press. 3 January 2013. Retrieved 3 January 2013.
  2. ^ Williams, Lois (20 September 2021). "Farmer calls out Doc over cost of flood protection". Hokitika Guardian. p. 3.
  3. ^ McMahon, Brendon (9 March 2023). "Wanganui River in-flood flows onto farms after council 'failed' to heed warning". RNZ. Retrieved 23 April 2023.
  4. ^ McMahon, Brendon (22 April 2023). "Stop banks 'strangle' West Coast river over 60 years". RNZ. Retrieved 23 April 2023.

43°02′07″S 170°25′50″E / 43.0353°S 170.4305°E / -43.0353; 170.4305

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