Source of the Blackwood River
The Blackwood River has its named source at the confluence of the Arthur and Balgarup Rivers, 40 kilometres north-east of the township of Boyup Brook. This is about 400 kilometres from the mouth at Hardy Inlet, Augusta.
Hydrologically, however, the watercourse termed the Arthur River is the same as the Blackwood. The Arthur River is termed as such from its confluence with the Yilliminning River in a salt lake system in the Arthur River Nature Reserve about 30 kilometres northwards of Wagin.
From this point, however, the watercourse has many inputs, including the Yilliminning. In most years, this is the source of the Blackwood River. The Yilliminning’s source is about eight kilometres south-west of Wickepin.
The Yilliminning flows about 34 kilometres south to its junction with the Arthur in the Nature Reserve. The Arthur flows about 140 kilometes generally south-west to its junction with the Balgarup River about 11 kilometres south-south-west of Moodiarrup from which point the two watercourses are named the Blackwood River.
Naming of the Blackwood and its source rivers
The Blackwood River was discovered on 6 May 1830 by Lieutenant Governor James Stirling, who led a party of settlers to found the town of Augusta. The exploration of the river on which this town was sited commenced the next day. Stirling, accompanied by Captains Currie and Molloy, James Woodward Turner, John Bussell and others ascended the river for a day and a half.
On Stirling’s return to Perth from Augusta, the Surveyor General of the fledging Swan River Colony, J.S. Roe, issued a Government Notice to advise prospective settlers of the area’s potential. The notice stated:
“The Inlet is of considerable extent and leads to a River named the Blackwood which was to the north about fifteen miles, and then ten miles to the East before it ceases to be navigable for boats.”
The Blackwood was named after either Vice Admiral Sir Henry Blackwood under whom Stirling had served during his early Royal Navy career or Captain Blackwood, later of the Fly and the Bramble.
The Arthur River was named by Stirling on 30 October 1835 during the Great Southern Expedition. It was named after Mr Arthur Trimmer, a member of the expedition.
The name for the Yilliminning River is of unknown aboriginal derivation, first recorded by Surveyor J.O. Oxley in 1892.
The first Europeans to explore the Blackwood River were a small party under the command of Thomas Turner. They set out from the settlement at Augusta in 1834 and travelled as far as where Nannup is now. It was to be eight years before further exploration occurred. Surveyor Augustus Gregory (after whom Mt Augustus is named) explored the upper reaches in 1845 and later carried out the first survey of the Blackwood Valley. The first settlers followed soon after.
Above Yilliminning is the Upper Catchment. This includes Lake Dumbleyung and the local gulleys and creeks that drain into it. Unless the lake overflows the Upper Catchment does not contribute to the flow of the Blackwood River. The Blackwood River catchment covers an area of approximately 22,000 square kilometres (an area slightly larger than Israel) and is the largest catchment in the South West of Western Australia. The greater part of the Blackwood Catchment is to the east of the Darling Scarp.
With a mean annual average flow of about 620 million cubic metres per year the Blackwood is the biggest river in Western Australia’s South West. This flow compares with a figure of 320 million cubic metres for the Avon River (measured at Walyunga National Park)
And although the Blackwood is the longest river with the largest flow in the South West it is puny by comparison with the mighty Ord River in the Kimberley. That river’s average annual flow is 4,300 million cubic metres. During one particularly wet year it discharged 12,500 million cubic metres into the ocean. This enormous quantity of water is the equivalent of all the divertible surface and groundwater resources of the whole State in an average year.
Measured at Winnejup Falls, about 18 kilometres upstream from Bridgetown, the average annual flow of the Blackwood River is 300 million cubic metres. So it can be seen that the Blackwood picks up as much water after Winnejup as before.
The river experienced its biggest recorded flood in January 1982. Extraordinary volumes of water flowed through the Blackwood River Valley during this freak summer flood. At Winnejup Falls, the flow was recorded at 1310 cubic metres per second (the peak for the Ord River is 33,000 cubic metres per second).
Length of the Blackwood River
|Glenorchy Bridge||Ualling Crossing||15||15|
|Ualling Crossing||Trigwell Bridge||13||28|
|Trigwell Bridge||Hicks Road||13||41|
|Hicks Road||Condinup Bridge||21||62|
|Condinup Bridge||Boyup Brook||16||78|
|Boyup Brook||Upper Blackwood Bridge||18||96|
|Upper Blackwood Bridge||Mandalup||11||107|
|Winnejup Bridge||Winnejup Falls||3||126|
|Laymans Flat||Punch Road||10||319|
|Punch Road||Sues Bridge||17||336|
|Sues Bridge||Warner Glen Bridge||27||363|
|Warner Glen Bridge||Alexander Bridge||13||376|
|Alexander Bridge||Molloy Caravan Park||13||389|
|Molloy Caravan Park||Augusta||10||399|
Expeditions on the upper Blackwood River
Epton, Kim, Rivers of the Kimberley, Hesperian Press, 2000.
De Silva, Smith, Rutherford and Ye, Hydrogeology of the Blackwood River Catchment Western Australia.
Roe, J.S., Fieldbook 10, SROWA, Series 2217, Cons 3401, Item ROEJ/10.
The Colony of Western Australia from the surveys of J.S. Roe, etc. John Ainsworth, London, 1839. Exploration Plan 124A, SROWA, Series 50, Cons 3423, Item 202.
Shoobert, (ed.), Western Australian Exploration Volume One December 1826−December 1835: The Letters, Reports & Journals of Exploration and Discovery in Western Australia, Hesperian Press, Carlisle, Western Australia, 2005, pp. 159-60, 468.
Genoma (data set of Geographic Place Names), WA Department of Land Information, Midland, undated, c. 1997.
© Kim Epton 2016-2019
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