Avon River (Western Australia)

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For other rivers called Avon, see River Avon.
Avon River
Avon vally gnangarra-36.jpg
Avon River flowing through the Avon Valley National Park
Native name <span class="nickname" lang="Error: invalid input "nys"; please use an ISO 639-1 code">Gulgulga Bilya
Origin East of Pingelly
Mouth Confluence with the Swan River near Perth
Basin countries Australia
Length 280 kilometres (170 mi) well-defined; much longer in paleodrainages
Source elevation c. 400 m (1300 ft.)
Mouth elevation 29 m (95 ft)
Avg. discharge averages 10 m3/sec but very erratic
Basin area 125,000 km2 (48,000 sq mi)
Location of the Avon River

The Avon River is a river in Western Australia. It is a tributary of the Swan River totalling 280 kilometres in length, with a catchment area of 125,000 square kilometres.[1]

Avon Catchment area[edit]

Lake Yealering in the Shire of Wickepin is the point of origin for the upper Avon river, and the catchment size above the confluence with the Salt River at Yenyenning Lake is 91 500 km2.[2]

The basin covers much of West Australian wheatbelt[3] and extends beyond that in some areas near almost-always-dry Lake Moore in the northeast, water is received regularly from only the extreme western edge of the basin. Indeed, until an abnormally wet year in 1963 it was not realised that the northeastern part of the basin beyond Wongan Hills ever drained water into the river. Under present climatic conditions, it is almost impossible to produce runoff from anywhere outside the extreme west of the basin because the amount of rain required to fall before runoff would begin is as high or higher than the mean annual rainfall.

The river flows past Quajabin Peak, creating a picturesque view from the top.

Subcatchments[edit]

Soils[edit]

Due to the extraordinary age of the soils in the basin (which is on the extremely ancient Yilgarn Craton), the rooting density of native flora is very high and its average specific discharge probably the lowest of any basin of comparable size in the world. The extreme age of the soils also means that, at least after clearing for agriculture, almost all rivers in the basin have salinities above 0.3% (one tenth that of the oceans and eight times that necessary to qualify as "fresh" water) and some much more than that.

Passing through some of the oldest settled European agricultural areas in Western Australia, the catchment area has extensive soil salinity issues, which have attracted governmental programmes to alleviate the loss of agricultural lands. Catchment groups that oversee projects in the tributary parts of the river have had considerable support and funding from commercial and non-governmental sources as well.

Tributaries[edit]

Thirty creeks and rivers flow into the Avon, some of the larger tributaries include the Dale River, Brockman River, Mortlock River and the Mackie River.[4] Most of these watercourese are ephemeral and only flow after rain events in winter and spring.

Pools[edit]

Some permanent pools exist along the course of the river including Burlong Pool Robins Pool, Long Pool, Cobblers Pool and Jimperding Pool.

Valley[edit]

The Avon River Valley is the third and final route for the Eastern Railway line through the Darling Scarp between Midland and Northam, having been constructed in the 1960s.

It is the site of an annual whitewater boating event, the Avon Descent.

References[edit]

  1. ^ http://slwa.wa.gov.au/swan_river/community_icon/the_swan-avon_river_and_its_catchments
  2. ^ http://www.wheatbeltnrm.org.au/about-us/our-region/avon-region/
  3. ^ Western Australia.(2008) Dept. of Water. Managing waterways in the Avon wheatbelt: field guide Perth, W.A. Dept. of Water - "This is an Avon Catchment Council project delivered by the Department of Water and funded with investment from the state and Australian governments through the Natural Heritage Trust and the National Action Plan for Salinity and Water Quality." "June 2008" http://henrietta.liswa.wa.gov.au/record=b2561801~S2 - Also available as an electronic version via the Internet. ISBN 978-1-921468-75-9
  4. ^ "Bonzle Digital Atlas – Map of Avon River". 2011. Retrieved 2011-09-17. 

External links[edit]

Further reading[edit]

  • Harris, T. F. W. (1996) The Avon : an introduction Perth, W.A.: Water and Rivers Commission ISBN 0-7309-6989-4

Coordinates: 31°44′01″S 116°04′29″E / 31.73361°S 116.07472°E / -31.73361; 116.07472