Lake Rotokawau (Bay of Plenty)
{{Short description|Lake in the North Island of New Zealand}}
{{Use New Zealand English|date=April 2024}}
{{Use dmy dates|date=October 2020}}
{{Infobox body of water
| name = Lake Rotokawau
| width =
| cities =
| islands =
| elevation = {{convert|320|m|abbr=on}}
| shore =
|pushpin_map=North Island
| pushpin_map_alt = Location of Lake Rotokawau
| residence_time =
| volume =
| max-depth = {{convert|74|m|abbr=on}}
| depth = {{convert|43.7|m|abbr=on}}
| area = {{convert|0.52|km2|abbr=on}}
| length =
| image = Lake Rotokawau.jpg
| basin_countries = New Zealand
| catchment = {{convert|2.23|km2|abbr=on}}
| outflow = Waiohewa Stream
| inflow = Waimata Stream
| type = maar lake
| coords = {{Coord|-38.07331|176.37935|region:NZ_type:waterbody|display=inline,title}}
| location = Bay of Plenty, North Island
| caption_bathymetry =
| image_bathymetry =
| caption = Aerial view of Lake Rotokawau in 2018
| alt = Aerial view of Lake Rotokawau in 2018
| reference =
}}
Lake Rotokawau is a small volcanic lake {{Convert|4.1|km||abbr=on}} east of Lake Rotorua in the Bay of Plenty region of New Zealand's North Island. The name is also used for lakes in the Kaipara District (Poutu Peninsula),{{Cite web|last=|first=|date=|title=Lake Rotokawau (Pöuto) Management Plan|url=https://www.nrc.govt.nz/media/9542/lakerotokawaupoutomanagementplanwebsite.pdf|archive-url=|archive-date=|access-date=|website=Northland Regional Council}} Chatham Islands,{{Cite web|title=Lake Rotokawau, Chatham Islands – NZ Topo Map|url=http://www.topomap.co.nz/NZTopoMap/ci294/Lake-Rotokawau/Chatham-Islands|access-date=1 October 2017|website=NZ Topo Map|language=en}} on Aupouri Peninsula{{Cite web|title=Lake Rotokawau, Northland|url=https://www.topomap.co.nz/NZTopoMap/nz10385/Lake-Rotokawau/|access-date=26 October 2020|website=NZ Topo Map|language=en}} and near Lake Waikare in Waikato.{{Cite web|title=Lake Rotokawau, Waikato – NZ Topo Map|url=http://www.topomap.co.nz/NZTopoMap/nz524/Lake-Rotokawau/Waikato|access-date=1 October 2017|website=NZ Topo Map|language=en}} Access is via Lake Rotokawau Road, from SH30 at Tikitere (Hell's Gate). The lake is owned and managed by Ngāti Rangiteaorere.{{Cite web|first1=Lisa |last1=Pearson |first2=David |last2=Hamilton |first3= Chris |last3=Hendy|date=July 2011|title=Lake Rotokawau: Water quality and sediment study|url=https://www.waikato.ac.nz/__data/assets/pdf_file/0003/472044/CBER_127_Lake-Rotokawau.pdf|url-status=|archive-url=|archive-date=|access-date=2022-08-28|website=University of Waikato}}
Ecology
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{{Infobox mapframe |coord={{coord|-38.07331|176.37935|type:waterbody_region:NZ|display=inline}}|area_km2=0.52|point=none|shape-fill-opacity=0|stroke-width=1}}}}
Lake Rotokawau is a small, oligotrophic lake; the best example of what many deep Rotorua lakes were once like. Koaro (Galaxias brevipinnis), banded kokopu (Galaxias fasciatus), long-finned eel (Anguilla dieffenbachia), short-finned eel (Anguilla australis), smelt (Retropinna retropinna) and common bully (Gobiomorphus cotidianus) live in the lake.
The catchment is roughly 65% forested and 25% in agriculture.
Geology
{{maplink|frame=yes
|frame-align=left
|text=Lake Rotokawau surface volcanics map with the predominant basaltic eruptives (brown) presumably from a dyke extending in a linear line from the smaller maar of Lake Rotoatua towards Tikitere. Clicking on the map enlarges it, and enables panning and mouseover of nearby volcanic feature name/wikilink and ages before present. The key to the other volcanics that are shown with panning is monogenic basalts - dark brown, undifferentiated basalts of the Tangihua Complex in Northland Allochthon - light brown, arc basalts - deep orange brown, arc ring basalts -orange brown, andesite - red, dacite - purple, rhyolite - violet , ignimbrite (lighter shades of violet), and plutonic - gray.
|raw={{Wikipedia:Map data/Northern North Island Volcanics}}
|frame-width=270
|frame-height=270
|frame-lat=-38.07331
|frame-long=176.39
|icon=no
|zoom=12
}}
The lake is a maar lake,{{Cite web|last=|first=|date=|title=R|url=http://www.geomarine.org.nz/NZGI/alpha/R.htm|url-status=|archive-url=|archive-date=|access-date=26 October 2020|website=www.geomarine.org.nz}}{{Cite web|last=Bruce W Hayward|date=July 2019|title=The Campaign to Save Crater Hill Continues|url=https://www.gsnz.org.nz/assets/Uploads/Shop/Products/Newsletters/28_2019-07_GSNZ_Newsletter.pdf|url-status=|archive-url=|archive-date=|access-date=2022-08-28|website=}} formed by an explosion about 4,000 years ago, leaving cliffs of up to {{Convert|90|m||abbr=on}} around the lake. The airfall eruptive volume was {{convert|0.7|km3|abbr=on}} and covered an area with tephra of {{convert|70|km2|abbr=on}} with a lava eruptive volume of {{convert|0.5|km3|abbr=on}}.{{cite thesis|title=The Rotokawau eruption |last1=Beanland |first1= Sarah |year=1981 |url=http://theses.otagogeology.org.nz/items/show/141 }}{{cite journal|title=A review of late Quaternary silicic and some other tephra formations from New Zealand: Their stratigraphy, nomenclature, distribution, volume, and age |first1=P. C. |last1=Froggatt |first2= D. J. |last2=Lowe |year=1990|issue=1 |pages=89–109 |doi=10.1080/00288306.1990.10427576 |journal= New Zealand Journal of Geology and Geophysics |volume=33|doi-access=free |hdl=10289/176 |hdl-access=free }} While the local rocks are rhyolite and pumice, with areas of alluvial sand and silt the formative eruption is one of only two, in a locality dominated by rhyolitic eruptions, recent basaltic fissure eruptions (the other is the 1886 eruption of Mount Tarawera).{{cite journal| first1=E.A. |last1=Bertrand |first2= P. |last2=Kannberg |first3= T.G. |last3=Caldwell |first4=W. |last4=Heise |first5= S. |last5=Constable |first6= B. |last6=Scott |first7= S. |last7=Bannister |first8= G. |last8=Kilgour |first9= S.L. |last9=Bennie |first10= R. |last10=Hart |first11= N. |last11=Palmer |title=Inferring the magmatic roots of volcano-geothermal systems in the Rotorua Caldera and Okataina Volcanic Centre from magnetotelluric models |journal=Journal of Volcanology and Geothermal Research |volume=431 |year=2022 |issue=107645 |page=107645 |issn=0377-0273 |doi=10.1016/j.jvolgeores.2022.107645 |s2cid=251526385 |url=https://www.sciencedirect.com/science/article/pii/S0377027322001767 }} Tephra from the eruption was dated at 3440 ± 70 years before 1950. The eruption had the characteristics of a basaltic dike as there is a line of eruptive vents almost at right angles to the usual vent alignments of the recently active Ōkataina Caldera. The maar crater is located almost exactly where this alignment intercepts a postulated continuation of the known fault defining the southern limit of the Tikitere Graben. The lake has one major inflow, the Waimata Stream, on the south side and also small geothermal springs on the north-west shore. The lake discharges via groundwater to the Waiohewa Stream, near Tikitere.
References
{{Reflist}}
External links
- [https://umedia.lib.umn.edu/item/p16022coll361:4903 1965 views of lake with drowned trees]
{{DEFAULTSORT:Rotokawau}}
Category:Lakes of the Bay of Plenty Region
Category:Rotorua Lakes District