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49-696: The Mangatangi River , or Mangatangi Stream, originates on the eastern slopes of the Hunua Ranges in New Zealand and flows roughly southwards until it is joined by the Ruaotehuia Stream just north of State Highway 2 between Mangatāwhiri and Maramarua , where it becomes the Maramarua River . Mangatangi can be translated as manga tangi to stream of weeping, or as rippling stream , or babbling brook. The dictionary defines

98-484: A sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of

147-414: A watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation , a common task in environmental engineering and science. In a closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as

196-591: A bridge, a Ratification Information Booklet and on Te Awa, RNZ , District Council , National Library and local historical group websites. The river starts as several small streams on the eastern slopes of the Hunua Ranges . Greywacke and argillite of the Waipapa Group form the High Hunua Horst and underlie the river in the Hunua Ranges. The south-eastern boundary of the horst is

245-454: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

294-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

343-565: A regional park open to the public. The ranges are located approximately 50 kilometres (30 mi) southeast of the main Auckland urban area, above the western shore of the Firth of Thames . They are sparsely populated, and mostly lie within the boundaries of the Waharau and Hunua Ranges Regional Parks. The settlement of Hunua lies at the foot of the Hunua Ranges. The ranges are covered by

392-424: A river as a large natural stream. The Mangatangi is called a stream by some sources and a river by others. The New Zealand Geographic Board hasn't given it an official name. The 1:50,000 map shows it as a Stream , but LAWA calls it a River , as does Regional Council in documents on swimming and flow, but a Stream in its catchment management plan. Other references to River are 1894 and 1895 requests for

441-656: A temporary bridge away, whilst a replacement was being built in 1922. Further upstream, Stubbs Bridge was also built in 1922, swept away in 1966 and replaced in 1967. In 1921 Franklin County Council rejected a tender for a bridge with concrete piers, a main span of 64 ft (20 m) and two 20 ft (6.1 m) side spans. Stubbs Bridge was opened on 22 December 1924 by Minister of Public Works, Gordon Coates . Introduced species include rainbow and brown trout . Koi carp and mosquitofish , have become major pests. Trout were introduced in 1885. Water quality

490-524: Is a mountain range and regional park to the southeast of Auckland city , in the Auckland and Waikato regions of New Zealand's North Island . The ranges cover some 250 square kilometres (97 sq mi) and rise to 688 metres (2255 ft) at Kohukohunui. Auckland Council owns and manages 178 square kilometres (69 sq mi) of the ranges, including part located in the Waikato region, as

539-473: Is high in the regional park, but degrades downstream with increasing agricultural land use, so that by the Watercare Services flow gauging weir, given consent in 2001, only eels and Crans bully ( Gobiomorphus basalis ) were recorded. Galaxiids are largely absent upstream of the weir. Longfinned and shortfinned eels , and Crans bully are common. Attempts were made in the past to trap eels, in

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588-487: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

637-614: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

686-400: Is the highest point in the Hunua Ranges. The New Zealand Ministry for Culture and Heritage gives a translation of "great mist" for Kohukohunui . Tāmaki Māori have traditionally used the ranges for a wide range of resources. The traditional name is Ngāherehere ō Kohukohunui ("The Expansive Forest of Kohukohunui"), named after Kohukohunui, the highest peak of the ranges. Te Hūnua

735-713: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

784-828: The Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of the world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan,

833-714: The Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of the Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains

882-598: The runoff . The removal of the native vegetation throughout the catchment to accommodate the increasing demand for farmland has contributed to the silting of the river with loose soils from eroded farmland. That would have been exacerbated by floating the felled logs down the stream, which was licensed under the Timber Floating Act 1873 till at least 1911. 37°13′28″S 175°10′29″E  /  37.224363°S 175.174833°E  / -37.224363; 175.174833 Hunua Ranges The Hunua Ranges

931-552: The Mangatangi Fault, which runs along the north-west side of the mid section of the river. The upper stream is typically shallow, fast flowing, with cobble and gravel substrate. As well as being a water and recreation resource, the river was historically a transport link. It also provided shingle to metal local roads and that use continues. A flax industry also existed as late as 1930. The earth-fill dam (2,140,000 m (76,000,000 cu ft), with stone facing,

980-623: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

1029-537: The Wairoa River, as one of the first crops of potatoes grown in New Zealand. The pigs were released into the Hunua Ranges, where they were hunted by Ngāi Tai. The main part of the ranges was subject to confiscation after the New Zealand Wars . Early European use of the ranges was for timber extraction and for farming but low soil fertility limited success. There has been some mining of Manganese in

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1078-500: The area: Upper Mangatawhiri (1965), Wairoa (1975) and Mangatangi (1977). Combined, the dams have a capacity of 77.1 million cubic meters, and supply approximately 68% of Auckland's potable water, through the Ardmore Water Treatment Plant. A decision was made to reforest the ranges in the early 1960s, after the area had gradually reverted into farmland. The bulk water supply operation and the land passed to

1127-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

1176-434: The belief that they damaged fisheries. Grey teal , brown teal and grey duck have been seen on the reservoir. Pollution measurements near the mouth of the river show that it is among the worst 25% of waterways in the country for a majority of pollutants. The catchment is mostly fertile farmland, so intensive agriculture is present and significant agricultural pollution is leached into groundwater and contained in

1225-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

1274-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

1323-697: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

1372-857: The eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ), the Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain

1421-498: The entire park was closed during a 1080 pest control programme . The programme was subject to an unsuccessful legal challenge. Activities in the regional park include walking, mountain-biking, bird-watching and drone-flying. Drainage basin Other terms for a drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called

1470-693: The first organisations in New Zealand to propagate native trees through grafting techniques, and were the first to successfully graft kauri trees. The forestry service was shut down in the late 1980s, as the Auckland Regional Authority was replaced with the Auckland Regional Council . The water operation was corporatised as Watercare Services in 1992, but the land itself remained with the Auckland Regional Council. Watercare took ownership of

1519-583: The greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to the Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains , a small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America ,

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1568-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

1617-781: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

1666-639: The islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through the Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of

1715-598: The largest area of native bush in Auckland, with streams, waterfalls, and hills overlooking the Auckland Region and Hauraki Gulf . Auckland gets much of its water from reservoirs sources from rivers and streams, including the Hunua Falls on the Wairoa River. The Mangatawhiri Ridge is one of the last remaining breeding grounds of the North Island kōkako . Kohukohunui (688 metres (2,257 ft))

1764-514: The most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

1813-469: The newly formed Auckland Regional Authority in 1964. The Authority completed the water supply development and continued the exotic afforestation on some of the north and western catchment land, started by the City Council, and its Water Department administered the land. The ranges were planted with a mix of exotic forest and native species, predominantly rimu . The forestry service nursery was one of

1862-563: The ownership of the former Auckland Regional Council park land went to the Auckland Council and that of the water assets is unchanged with Watercare Services. Extensive flooding in the Hunua Ranges in March 2017 cut off roads. People staying on the ranges had to be evacuated. In May 2018, parts of the park were closed to stop the spread of Kauri dieback . Some of the tracks reopened in late 2020. In September and October 2018,

1911-414: The past. Gold prospecting for quartz reefs has never found payable reefs. From the 1920s onwards the land was progressively bought by Auckland City Council utilising funds from its water supply operation. Development of the water supplies commenced in 1946, with the first of the four dams, Cossey's, completed with a capacity of 11.3 million cubic meters in 1956. Three embankment dams were constructed in

1960-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

2009-631: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

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2058-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

2107-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

2156-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

2205-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

2254-411: The water related assets and took a long term lease from the Auckland Regional Council of the reservoir areas and the operational areas. The exotic forestry land was also leased to another party. The catchment land became regional park land. In November 2010, the southernmost part of the Hunua Ranges were transferred to Waikato region. This determines the local government administrative boundaries, but

2303-673: The world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins, the Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of the Andes also drains to the Atlantic, as does most of Western and Central Europe and

2352-675: Was a name used to describe the wider country between the Wairoa River valley and Papakura . Māori made some use of the ranges and early European visitors found areas of clearing that had been used as gardens. Ngāi Tai ki Tāmaki are tangata whenua for the ranges, and many archaeological sites are known within the ranges. In November 1769, Captain Cook visited the Hauraki Gulf area. Cook gifted pigs and potatoes to senior members of Te Uri ō Pou from Ōrere , who then planted these along

2401-428: Was built between 1972 and 1977, on a foundation drainage filled with greywacke , with a 67 m (220 ft) high bellmouth spillway . It is 340 m (1,120 ft) wide, 78 m (256 ft) high and can hold 39,000,000 m (8.6 × 10 imp gal) of water covering 169 ha (420 acres). In 1897 Whangamarino Road Board built a girder bridge across the river. By 1914 it was in disrepair. A flood swept

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