The Puniu River is a river of the

Waikato The Waikato () is a region of the upper North Island of New Zealand. It covers the Waikato District, Waipā District, Matamata-Piako District, South Waikato District and Hamilton City, as well as Hauraki, Coromandel Peninsula, the nort ...

region of New Zealand's

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

. 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 Kūiti. It flows north for , passing through Ōtorohanga and Pirongia, before flowing into the Waikato Ri ...

(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, veering northwest to pass south of the towns of Kihikihi and

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

before meeting the

south of

Pirongia Pirongia is a small town in the Waipā 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 Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

to Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Manaia Hill Group

greywacke Greywacke or graywacke ( ) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and Sorting (sediment), poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size Lith ...

(a form of

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

, with little or no

bedding Bedding, also called 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 environment ...

, 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 sedimen ...

with

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

and conglomerate, and with many

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

veins Veins () are blood vessels in the circulatory system of 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 those of the pulmonary and fetal c ...

), which is buried in many places by

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

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 surrou ...

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

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

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 predomina ...

and

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

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 (, ) 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. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

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, Sheet erosion , sheetwash, slow continuous downslope creep, or a va ...

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

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

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 geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

floodplain, where the alluvium and colluvium consist of variously coloured, unconsolidated sand, silt, mud, clay, local gravel and thin intercalated (a form of interbedding, where distinct deposits in close proximity migrate back and forth) peat beds.

Vegetation

The river rises in the Pureora Forest Park, before flowing past some unprotected remnants of

rimu ''Dacrydium cupressinum'', commonly known as rimu, is a species of tree in the family Podocarpaceae. It is a dioecious evergreen conifer, reaching heights of up to , and can have a stout trunk (botany), trunk up to in diameter. It is endemis ...

- 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 a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

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 both water clarity and wa ...

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

Bridges

The river originally had a seasonal ford near Kihikihi. The first bridge there was built about 1885, when the long

railway Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in railway track, tracks, which usually consist of two parallel steel railway track, rails. Rail transport is one of the two primary means of ...

bridge was also built. A

ferro-concrete Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion of reinforcement having ...

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