Gairdner River (Great Southern, Western Australia)

{{Short description|River in Western Australia}}

{{Distinguish|Gairdner River (Kimberley, Western Australia)}}

{{Use dmy dates|date=March 2015}}

{{Use Australian English|date=March 2015}}

{{Infobox river

| name = Gairdner River

| image = Gairdnerriver.jpg

| image_caption = Gairdner River near West Mount Barren

| map = {{Infobox mapframe |wikidata=yes |zoom=9 |frame-height=300 | stroke-width=2 |coord={{WikidataCoord|display=i}}|point = none|stroke-color=#0000FF |id=Q5517333 }}

| source1_location = Needilup-Jacup

| mouth_location = Gordon Inlet

| subdivision_type1 = Country

| subdivision_name1 = Australia

| length = {{convert|130|km|mi|0}}

| source1_elevation = {{convert|320|m|ft|0}}{{cite web|url=http://maps.bonzle.com/c/a?a=p&cmd=sp&zix=r&p=210340&st=&s=Gairdner%20River&pg=1&m=0&c=1&x=124%2E736415&y=%2D15%2E575425&w=17911|title=Bonzle Digital Atlas - Map of Gairdner River, WA|year= 2008|access-date= 24 November 2008}}

| discharge1_avg = {{convert|940,000|ML/yr|m3/s cuft/s|abbr=on}}{{cite web|url=http://www.rivercare.southcoastwa.org.au/infodata/gairdnerc/gairdnerr/gairdner.html|title=South Coast Rivercare - Gairdner River|year= 2007|access-date= 25 May 2010}}

| basin_size = {{convert|1770|km2|mi2|0}}

}}

Gairdner River is a river located in the Great Southern region of Western Australia.

The river was first recorded by Surveyor General John Septimus Roe in 1848, when carrying out exploration of the area, noting that natives referred to it and its numerous branches as "Jeer-A-Mung-Up". Roe later named the same river Gairdner River, at its mouth in Gordon Inlet, not realising they were the same, after Gordon Gairdner, Senior Clerk of the Australian and Eastern Departments in the Colonial Office, later Chief Clerk of the Colonial Office and Secretary and Registrar of the Most Distinguished Order of Saint Michael and Saint George.{{cite journal |last1=Roe |first1=John Septimus |author1-link=John Septimus Roe |title=Report of an Expedition under the Surveyor-General, Mr. J[ohn] S[eptimus] Roe, to the South-Eastward of Perth, in Western Australia, between the months of September, 1848, and February, 1849, to the Hon. the Colonial Secretary. |journal=Journal of the Royal Geographical Society of London |date=26 November 1849 |volume=XXII |pages=1-57 |access-date=26 October 2021 |url=https://gutenberg.net.au/ebooks13/1305031h.html|location=London}}{{cite journal | title = Colonial Office, Downing Street, May 28, 1874. | journal = The London Gazette | date = 29 May 1874 | issue = 24099| page = 2820| url = http://www.london-gazette.co.uk/issues/24099/pages/2820/page.pdf | format = pdf | access-date = 2012-03-28}} Roe also named Gordon Inlet and Mount Gordon after Gairdner.{{LandInfo WA|r|G|5 September 2011}}

The river originates in farm land north of the South Coastal Highway between Needilup and Jacup on the Yilgarn plateau at about {{convert|320|m|ft|0}} above sea level. It flows in a south-easterly direction crossing the South Coast Highway east of Jerramungup then through the Fitzgerald River National Park until it terminates in Gordon Inlet, where it discharges an average of 9,400,000 cubic metres per annum.

The tributaries that flow into the river are Cobomup Creek, Needilup River, Pingamup River, Spring Creek, Wilgerup Creek, Scott Creek and Duleep Creek.

About 60% of the catchment has been cleared for sheep and grains farming and as a result the water quality has become saline. Salinity levels vary from 3‰ (3,000 ppm) after rains when the river is flowing to 50‰ (50,000 ppm) during the summer time.