The Puniu River is a river of the

Waikato Waikato () is a local government region of the upper North Island of New Zealand. It covers the Waikato District, Waipa District, Matamata-Piako District, South Waikato District and Hamilton City, as well as Hauraki, Coromandel Peninsul ...

region of New Zealand's North Island. As a tributary of the

Waipā River The Waipā River is in the Waikato region of the North Island of New Zealand. The headwaters are in the Rangitoto Range east of Te Kuiti. It flows north for , passing through Ōtorohanga and Pirongia, before flowing into the Waikato River ...

(itself a tributary of the

Waikato River The Waikato River is the longest river in New Zealand, running for through the North Island. It rises on the eastern slopes of Mount Ruapehu, joining the Tongariro River system and flowing through Lake Taupō, New Zealand's largest lake. It th ...

), and at a length of , it is one of the longest secondary tributaries in New Zealand. The Puniu flows initially north from sources within the

Pureora Forest Park Pureora Forest Park is a protected area in the North Island of New Zealand. Within its rich rainforest are an abundance of 1,000-year-old podocarp trees. It is "recognised as one of the finest rain forests in the world". Established in 1978, a ...

, veering northwest to pass south of the towns of

Kihikihi Kihikihi, a small town located in the Waikato region of the North Island of New Zealand, serves as a satellite community of Te Awamutu, five kilometres to the north, and lies 35 kilometres south of Hamilton. The 2018 New Zealand census recorded ...

and

Te Awamutu Te Awamutu is a town in the Waikato region in the North Island of New Zealand. It is the council seat of the Waipa District and serves as a service town for the farming communities which surround it. Te Awamutu is located some south of Hamilt ...

before meeting the

south of

Pirongia Pirongia is a small town in the Waipa District of the Waikato region of New Zealand's North Island. It is 12 kilometres to the west of Te Awamutu, on the banks of the Waipā River, close to the foot of the 962 metre Mount Pirongia, which lies i ...

Geology

About half the river's course from its sources on the edge of the Rangitoto Range is through deep valleys and gorges formed of Late

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

to Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Manaia Hill Group

greywacke Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...

(a form of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

, with little or no

bedding Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...

, fine to medium grained,

interbedded In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedim ...

with siltstone and conglomerate, and with many

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

), which is buried in many places by Quaternary

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surro ...

s. The main ignimbrite is the Ongatiti Formation, up to 150 m thick of compound, weakly to strongly welded, vitrophyric (

phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...

s embedded in a glassy rock), including

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...

and rhyolite lavas. In several places the river runs past slopes covered in blocks of ignimbrite, where the underlying greywacke has eroded. For the remainder of its course, the river meanders over

alluvium Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...

and

colluvium Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combinati ...

to the Waipa. Initially these are mainly the Late Quaternary Piako Subgroup, which includes Late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

alluvium, and minor fan deposits of unconsolidated to very soft, thinly to thickly bedded, yellow-grey to orange-brown, pumiceous mud, silt, sandy mud and gravel, with local muddy peat. Finally, the river flows mostly over the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

floodplain, where the alluvium and colluvium consist of variously coloured, unconsolidated sand, silt, mud, clay, local gravel and thin intercalated (a form of

interbedding In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedimen ...

, where distinct deposits in close proximity migrate back and forth) peat beds.

Vegetation

The river rises in the

, before flowing past some unprotected remnants of

rimu ''Dacrydium cupressinum'', commonly known as rimu, is a large evergreen coniferous tree endemic to the forests of New Zealand. It is a member of the southern conifer group, the podocarps. The Māori name ''rimu'' comes from the Polynesian ...

- tawa forest. In its lower reaches the river mostly flows through farmland, where the Puniu River Care Project is working on restoration of the river.

Speed of flow

In its final from Tokanui flows usually take 9 to 17 hours, depending on river levels.

Pollution

The Puniu is 6th dirtiest out of 13 sampling points in the Waipa catchment, with unsatisfactory

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

and

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids ...

levels. Puniu is the only river in Waikato with worsening ammonia levels.

Bridges

The river originally had a seasonal ford near

. The first bridge there was built about 1885, when the long

railway Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...

bridge was also built. A

ferro-concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion ...

bridge replaced the old wooden bridge, downstream. It was largely built in 1936, completed in 1937 and still serves SH3.

References

External links

Current river level.

Water quality monitoring at Bartons Corner Rd

Rainfall at Pokuru Road Bridge, Te Awamutu
an
Ngaroma

Water level at Pokuru Road Bridge, Te Awamutu

photo of old bridge about 1921

1936 photos of bridge and road deviation under construction
{{coord, 38, 01, S, 175, 13, E, display=title, region:NZ_type:river_source:GNS-enwiki1:50,000 map
sourcemouth
Google Maps 'Street Views' from the six bridges over the river
Pokuru Rd
SH3br>Otorohanga RdBayley RdWharepapa S RdBayley RdNgaroma Rd
Rivers of Waikato Rivers of New Zealand