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25-588: The Matukituki River is a short braided river in the Southern Alps of New Zealand 's South Island . Both its West Branch and East Branch originate from the Main Divide mountain ranges near Mount Aspiring / Tititea . Their largely glacier-fed waters each flow for approximately 20 kilometres (12 mi) before joining near Camerons Flat. After this confluence, the Matukituki River leaves

50-406: A meandering river , which has a single sinuous channel. It is also distinct from an anastomosing river , which consist of multiple interweaving semi-permanent channels which are separated by floodplain rather than channel bars; these channels may themselves be braided. The physical processes that determine whether a river will be braided or meandering are not fully understood. However, there

75-799: A Department of Conservation NZ car park at the Raspberry Creek shelter. The most popular walk in the area is the Rob Roy Glacier walk, which leads up a side valley to a view point beneath Rob Roy Glacier. The walking track crosses the Matukituki River West Branch over a swing bridge . Braided river Braided streams tend to occur in rivers with high sediment loads or coarse grain sizes, and in rivers with steeper slopes than typical rivers with straight or meandering channel patterns. They are also associated with rivers with rapid and frequent variation in

100-542: A meandering profile. A stream with cohesive banks that are resistant to erosion will form narrow, deep, meandering channels, whereas a stream with highly erodible banks will form wide, shallow channels, preventing the helical flow of the water necessary for meandering and resulting in the formation of braided channels. Braided rivers occur in many environments, but are most common in wide valleys associated with mountainous regions or their piedmonts or in areas of coarse-grained sediments and limited growth of vegetation near

125-404: A dendritic system, or of cohesive sediments with no bedload transport. Meanders fully develop only when the river banks are sufficiently stabilized to limit lateral flow. An increase in suspended sediment relative to bedload allows the deposition of fine erosion -resistant material on the inside of a curve, which accentuated the curve and in some instances, causes a river to shift from a braided to

150-535: A narrow gorge and under the West Wanaka bridge just before Lake Wānaka. Most of the Southern Alps started over 220 million years ago as sediment and rock on top of volcanic rocks on the seafloor. Intense heat and pressure consolidated the rock, and then uplifted it to form the Main Divide. The present landscape was shaped by glacial processes during the ice ages , when huge glaciers filled and scoured out

175-426: A straight channel. Also important to channel development is the proportion of suspended load sediment to bed load . An increase in suspended sediment allowed for the deposition of fine erosion -resistant material on the inside of a curve, which accentuated the curve and in some instances, caused a river to shift from a braided to a meandering profile. These experimental results were expressed in formulas relating

200-402: A variation in sediment load, provided the amount of water carried by the river is unchanged. A threshold slope was experimentally determined to be 0.016 (ft/ft) for a 0.15 cu ft/s (0.0042 m /s) stream with poorly sorted coarse sand. Any slope over this threshold created a braided stream, while any slope under the threshold created a meandering stream or – for very low slopes –

225-654: Is home to a ski resort ( Treble Cone ), a jetboat operator (River Journeys) and numerous tramping (walking) trails providing access to landmarks such as the Rob Roy Glacier, the Dart Saddle , and the Cascade Saddle . The unsealed Wanaka - Mount Aspiring Road follows the river's true right for most of its course, past the confluence of the East Branch and West Branch, and part-way along the West Branch to

250-403: Is wide agreement that a river becomes braided when it carries an abundant supply of sediments. Experiments with flumes suggest that a river becomes braided when a threshold level of sediment load or slope is reached. On timescales long enough for the river to evolve, a sustained increase in sediment load will increase the bed slope of the river, so that a variation of slope is equivalent to

275-618: The Mount Aspiring National Park , New Zealand that takes approximately four days to complete. It is known for its "spectacular" views but is considered an expert-level track due to the hazardous conditions. The route is typically undertaken from east to west and links the Matukituki Valley with the Dart River valley . The start of the track is accessed from Wānaka and the end of the track links with

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300-583: The Rakaia and Waitaki Rivers of New Zealand are not aggrading, due to retreating shorelines, but are nonetheless braided rivers. Variable discharge has also been identified as important in braided rivers, but this may be primarily due to the tendency for frequent floods to reduce bank vegetation and destabilize the banks, rather than because variable discharge is an essential part of braided river formation. Numerical models suggest that bedload transport (movement of sediment particles by rolling or bouncing along

325-640: The Rees and Dart Tracks , with the exit towards Queenstown . Accommodations are available along the route in the Aspiring Hut and in the Dart Hut. There is a steep scrambling climb from Aspiring Hut towards the Cascade Saddle itself, reaching a maximum elevation of 1,835 m (6,020 ft). The views of Matukituki Valley from the saddle have been reported as "spectacular". The route then follows

350-437: The amount of water they carry, i.e., with " flashy " rivers, and with rivers with weak banks . Braided channels are found in a variety of environments all over the world, including gravelly mountain streams, sand bed rivers, on alluvial fans , on river deltas , and across depositional plains. A braided river consists of a network of multiple shallow channels that diverge and rejoin around ephemeral braid bars . This gives

375-562: The boundaries of Mount Aspiring National Park and continues for another 30 kilometres (19 mi) to exit into Lake Wānaka at the lake's southwestern edge. Six glaciers feed tributary streams to the Matukituki River, the largest being the Upper Volta Glacier, Rob Roy Glacier , Maud Francis Glacier, and the Avalanche Glacier. From Camerons Flat onwards, the river is increasingly braided until it passes through

400-426: The critical slope for braiding to the discharge and grain size. The higher the discharge, the lower the critical slope, while larger grain size yields a higher critical slope. However, these give only an incomplete picture, and numerical simulations have become increasingly important for understanding braided rivers. Aggradation (net deposition of sediments) favors braided rivers, but is not essential. For example,

425-717: The left bank of the Dart River and includes views of the Dart Glacier . The tramping route has been highlighted as one of the most dangerous, both in New Zealand and worldwide, due to the hazardous alpine nature of the track. The route is maintained by the Department of Conservation , who recommend it is best attempted by experienced trampers. A 2014 proposal to install safety rails was not adopted, partly so as not to encourage attempts by less-experienced hikers. In 2005 an Irish doctor, Donal Deery, lost his life on

450-546: The river a fancied resemblance to the interwoven strands of a braid . The braid bars, also known as channel bars, branch islands, or accreting islands, are usually unstable and may be completely covered at times of high water. The channels and braid bars are usually highly mobile, with the river layout often changing significantly during flood events. When the islets separating channels are stabilized by vegetation, so that they are more permanent features, they are sometimes called aits or eyots. A braided river differs from

475-595: The river banks. They are also found on fluvial (stream-dominated) alluvial fans . Extensive braided river systems are found in Alaska , Canada , New Zealand 's South Island , and the Himalayas , which all contain young, rapidly eroding mountains. Cascade Saddle Track The Cascade Saddle Track , also known as the Cascade Saddle Route , is a 25 km (16 mi) alpine tramping track in

500-414: The river bottom) is essential to formation of braided rivers, with net erosion of sediments at channel divergences and net deposition at convergences. Braiding is reliably reproduced in simulations whenever there is little lateral constraint on flow and there is significant bedload transport. Braiding is not observed in simulations of the extreme cases of pure scour (no deposition taking place), which produces

525-475: The seed-eating kākāriki specifically prefers areas of red beech. Paradise shelduck thrive on the river flats, and in summer, spur-winged plover and oystercatchers are a common sight on farmland and along the drive from Wānaka. The valley is also home to the kea , whio , South Island robin , rock wren , the South Island long tailed bat , and several species of lizards. The Matukituki River valley

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550-484: The shores of Lakes Wānaka and Hāwea , including Nehenehe on the northern banks of the mouth of the Matukituki River, which they called "Mātakitaki". Ovens for cooking tī kōuka (cabbage tree) roots have been found at several sites on the lake shore. Ngāi Tahu kaumātua recorded Mātakitaki as a kāinga mahinga kai (food-gathering place) for tuna (eels), kāuru (cabbage tree root), and aruhe (bracken fernroot). The first European to see Mount Aspiring

575-404: The valley, while mountain beech dominates the drier, eastern end. The understory of the typically open forests supports a variety of ferns and mosses. Above the tree line, at about 1,100 metres (3,600 ft), stunted, sub-alpine shrub land gives way to alpine tussock grasslands and fell fields. Insect-eating birds such as pīwakawaka , tomtit and rifleman thrive in the beech forest, whereas

600-572: The valleys. The area around Mount Aspiring, called Tititea by the Māori , has a long history of Māori tribes coming from as far as Coastal Otago and the Foveaux Strait to the inland lakes to collect kākāpō , kererū , kākā and tūī from the forest. Moa would have also have lived along the forest edges for the first 200 years of Māori settlement. The historic Māori iwi (tribes) of Kāti Māmoe and Ngāi Tahu both had named settlements around

625-478: Was government surveyor John Turnbull Thompson in 1857. The West Matukituki Valley was explored by James Hector in 1862. Sheep and cattle farming began progressing up the valley in the 1870s. Today, beech is the dominant forest in the Matukituki Valley. Red beech prefers warmer valley sites, and is common just below Aspiring Hut . Silver beech grows increasingly towards the wetter, western end of

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