Murchison River (Western Australia)
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The Murchison River is the second longest river in
Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
. It flows for about from the southern edge of the Robinson Ranges to the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
at Kalbarri. The Murchison-Yalgar-Hope river system is the longest river system in Western Australia. It has a mean annual flow of 208 gigalitres, although in 2006, the peak year on record since 1967, flow was 1,806gigalitres.


Basin

The Murchison River basin covers an area of about in the
Mid West region of Western Australia The Mid West region is one of the nine regions of Western Australia. It is a sparsely populated region extending from the west coast of Western Australia, about north and south of its administrative centre of Geraldton and inland to east o ...
. It extends about inland from the Indian Ocean, onto the
Yilgarn Craton The Yilgarn Craton is a large craton that constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have b ...
east of Meekatharra and north 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) ...
. Rain generally falls in the upper basin during summer cyclones, so for much of the year the Murchison River does not flow, leaving a dry sandy river bed and intermittent permanent pools. The eastern reaches of the basin contain large chains of salt lakes, which flow only following rainfall. The drainage lines from these lakes merge to form the Murchison River about north-northeast of Meekatharra. From here the river flows west, then southwest, then west to the Indian Ocean. Within the basin are the towns of Kalbarri and Meekatharra; the hamlets of
Ajana Ajana is a townsite within the Shire of Northampton in Western Australia. It is located at the junction of Ajana-Kalbarri Road and Ajana Back Road, by road north of Northampton, by road southwest of Kalbarri, and west-northwest of Perth in t ...
,
Binnu Binnu is a town on the North West Coastal Highway in the Mid West region of Western Australia. The name derives from a well on the outskirts of town that was first in use in 1909. The name is Indigenous Australian in origin and is thought to mea ...
, Barrel Well and Murchison; and the mining ghost towns of Galena, Geraldine, Abbotts, Chesterfield, Yaloginda, Reedy, Nannine, Quinns, Burnakura and
Gabanintha Gabanintha is a ghost town located in the Mid West region of Western Australia approximately 40 km south east of Meekatharra on the Meekatharra-Sandstone road. The town is situated within the Murchison goldfields. The name of the town i ...
.


Course

The Murchison River rises on the southern slopes of the Robinson Ranges, about north of Meekatharra in central
Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
. From there it flows in a westerly direction for about to its junction with its largest tributary, the Yalgar River, then west for another before turning south-southwest for , at which point it is joined by the Roderick River, about east of Murchison Settlement. Another to the south-southwest it joins another important tributary, the Sanford River. Over the next it makes a number of sharp turns, taking it about to the west. It then flows to the southwest, flowing under the
North West Coastal Highway North West Coastal Highway is a generally north-south Western Australian highway which links the coastal city of Geraldton with the town of Port Hedland. The road, constructed as a sealed two-lane single carriageway, travels through remote and ...
at the Galena Bridge. Entering the
Kalbarri National Park Kalbarri National Park is located north of Perth, in the Mid West region of Western Australia. The major geographical features of the park include the Murchison River gorge which runs for nearly on the lower reaches of the Murchison River. Sp ...
, it flows first to the northwest and then to the north, flowing through the
Murchison Gorge Murchison River Gorge is a riverine gorge in Mid West (Western Australia), Mid West Western Australia. Carved by the meandering lower reaches of the Murchison River (Western Australia), Murchison River, it is more than long, and up to deep. It ...
, and passing through a number of tight bends known as the
Z Bend The Z Bend lookout is a popular tourist lookout on the Murchison River Gorge in Western Australia. It is located at ,Gazetteer of Australia (1996). Belconnen, ACT: Australian Surveying and Land Information Group. about east of Kalbarri, in th ...
and The Loop respectively. It eventually turns to the southwest, passing through one more dogleg before discharging into the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
at Kalbarri, the only town on the river.


Murchison Gorge

Murchison Gorge is a deep gorge in near pristine condition. It is popular with tourists, and there are a number of tourist lookouts. It is also of geological interest, as it exposes a section through the
Tumblagooda Sandstone The Tumblagooda Sandstone is a geological formation deposited during the Silurian or Ordovician periods, between four and five hundred million years ago, and is now exposed on the west coast of Australia in river and coastal gorges near the tour ...
, a
geological sequence In geology, a sequence is a stratigraphic unit which is bounded by an unconformity at the top and at the bottom. Definition In a more rigorous and general way a sequence is defined as a "relatively conformable .. genetically related succession ...
rich in
Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
trace
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s. The maximum age for the initiation of major down-cutting of the Murchison Gorge, as a response to regional
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). It follows the Neogene Period and spans from 2.58 million years ...
tectonism Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...
, is
Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "daw ...
(33.9–38 million years ago).


Estuary

The final of the Murchison River, from the Murchison House ford to the mouth, are estuarine, and consist of a sequence of long
sandbar In oceanography, geomorphology, and Earth science, geoscience, a shoal is a natural submerged ridge, bank (geography), bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body o ...
s and shallow pools mostly less than a metre deep. The estuary is permanently open to the sea, so is constantly affected by
tide Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide t ...
s and the inflow of saline sea water. When river flow is low, the estuary accumulates
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
from the ocean, narrowing the river channel; this sediment is evacuated to the ocean during periods of high flow, but high flow also brings sediment into the estuary from upriver. Because of the high sediment load, and continual stirring by wind and river flow, the water is
turbid 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 can ...
. The mouth of the estuary is a small
delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...
, closed by a sandbar except for a narrow channel. Although this channel is permanently open, it is usually very narrow and shallow, and so is now dredged every year to allow passage by
western rock lobster Western may refer to: Places *Western, Nebraska, a village in the US *Western, New York, a town in the US * Western Creek, Tasmania, a locality in Australia *Western Junction, Tasmania, a locality in Australia *Western world, countries that i ...
fishing boats.


History

The Murchison River was named by the explorer
George Grey Sir George Grey, KCB (14 April 1812 – 19 September 1898) was a British soldier, explorer, colonial administrator and writer. He served in a succession of governing positions: Governor of South Australia, twice Governor of New Zealand, Go ...
, whose boats were wrecked at its mouth on 1April 1839, during his second disastrous exploratory expedition; the name honours Grey's patron, the Scottish
geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
Sir Roderick Murchison. Murchison's advocacy had been essential in securing official support for Grey's Western Australian expeditions. Murchison House Station, one of the oldest stations in Western Australia, was established by Charles Von Bibra on the banks of the river toward the western end in 1858. The estuary and river mouth was used as a holiday destination by families from the Galena mines in the 1920s and 1930s, and a military holiday camp was built there during World WarII. In 1951 the town of Kalbarri was gazetted at the river mouth, and by the end of the 1990s the population was about 2,000. In 1963 the
Kalbarri National Park Kalbarri National Park is located north of Perth, in the Mid West region of Western Australia. The major geographical features of the park include the Murchison River gorge which runs for nearly on the lower reaches of the Murchison River. Sp ...
was gazetted, formally protecting the lower reaches of the river, including the gorge. The Galena Bridge, carrying
North West Coastal Highway North West Coastal Highway is a generally north-south Western Australian highway which links the coastal city of Geraldton with the town of Port Hedland. The road, constructed as a sealed two-lane single carriageway, travels through remote and ...
over the river at Galena, was opened by the Main Roads Department in December 1983.


Flooding

Flooding occurred in 1866 resulting in the ''Geraldine Mine'' being drowned; more flooding occurred in 1882. The southern branch flooded out to a distance of from the river bank in 1884 and the main homestead at
Moorarie Station Moorarie Station is a pastoral lease currently operating as a sheep station in the Murchison district of Western Australia's Mid West region. The property is situated approximately northwest of Meekatharra and east of Carnarvon. It is wa ...
was washed away with about 3,000 ewes and lambs. The river was once again flooded in 1900 following heavy rains with the river estimated to be running wide, road to Cue and Peak Hill were submerged under of water. Roads were cut for up to a fortnight resulting in food shortages in many isolated towns. Ernest Lee Steere of
Belele Station Belele Station is a pastoral lease in Western Australia that operates as a cattle station and as a sheep station for the production of wool. Description The station is located in the Murchison region of Western Australia; the nearest town is ...
reported that over of rain fell in less than a fortnight. Further downstream the river was reported to be running wide and at depths of up to ; despite the damage, pastoralists were jubilant at how quickly the grasses were growing. Heavy flooding occurred along parts of the river in March 1926 following heavy rains. 15 to 20 men were left stranded at the ''Three Sister'' galena mine and had to be rescued by dingy. Flooding again occurred in 1939 and once more following another significant rain event in February 1945 that resulted in flooding and the old Galena Bridge being swept away, effectively stranding the citizens of Carnarvon. A
ferry A ferry is a ship, watercraft or amphibious vehicle used to carry passengers, and sometimes vehicles and cargo, across a body of water. A passenger ferry with many stops, such as in Venice, Italy, is sometimes called a water bus or water taxi ...
service was established using a fishing boat.
Banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus ''Musa''. In some countries, bananas used for cooking may be called "plantains", distinguis ...
s were the main item that urgently needed to be sent across for transport to market. Following Cyclone Emma in 2006, much of the catchment area received of rainfall. The river swelled, reaching a width of over in places, and Kalbarri had to be sandbagged to protect it from floodwaters.


See also

* Bilyuin Pool *
Murchison Gorge Murchison River Gorge is a riverine gorge in Mid West (Western Australia), Mid West Western Australia. Carved by the meandering lower reaches of the Murchison River (Western Australia), Murchison River, it is more than long, and up to deep. It ...
* Pencell Pool * Wooleen Station


References


Further reading

*Curry, P.J. et al. (1994) ''An inventory and condition survey of the Murchison River catchment and surrounds, Western Australia''. Department of Agriculture, Western Australia: Technical Bulletin Number 84. *Western Australia. Dept. of Land Administration. Cartographic Services Branch.(1991) ''Land systems of the Murchison River catchment and surrounds'' : map series to accompany W.A. Department of Agriculture technical bulletin no. 84 Map Data: Scale 1:250,000 (E 115° 10′--E 118° 45′/S 25°—S 28° 10′).Notes: ''Land systems of the Murchison River catchment and surrounds'' by K.A. Leighton ...
t al. T, or t, is the twentieth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is deri ...
Date of survey: 1986-1988. Location maps:Belele, Byro, Cue, Glenburgh, Murgoo, Robinson Range. {{Authority control Rivers of the Mid West region Kalbarri, Western Australia