Editing Swan River (Western Australia) (section)

===Flood events===
{{Bar chart
|title=Return period of flood events
|table_width=20
|float=right
|bar_width=35
|data_max=100
|label_type=Year<ref>{{cite web |url=http://www.ga.gov.au/image_cache/GA6527.pdf |website=Public Works Department |year=1986 |title=Avon River Flood Study: Revision A, prepared by Binnie and Partners Pty Ltd, Perth |access-date=15 January 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110317053858/http://www.ga.gov.au/image_cache/GA6527.pdf |archive-date=17 March 2011 }}</ref>
|data_type=Return period (years)
|label1=1862 |data1=60
|label2=1872 |data2=100
|label3=1910 |data3=20
|label4=1917 |data4=20
|label5=1926 |data5=30
|label6=1930 |data6=15
|label7=1945 |data7=20
|label8=1946 |data8=10
|label9=1955 |data9=20
|label10=1958 |data10=20
|label11=1963 |data11=15
|label12=1964 |data12=10
|label13=1983 |data13=10
}}
Data collection of flood events in the estuary has been performed since European arrival in 1829. In July 1830, barely a year after the establishment of the colony, the river rose {{convert|6|m}} above its normal level.<ref name="miro05" />{{rp|p=102}} New settlers were still arriving in steady numbers and few permanent buildings had been constructed, with most living in tents and other temporary accommodation. These included caves along the river's edge and many found their belongings washed away and livestock drowned.<ref>{{cite wikisource |wslink=History of West Australia |editor-first=Warren Bert |editor-last=Kimberly |editor-link=Warren Burt Kimberly |publication-date=1897 |page=55 |publication-place=Melbourne |publisher=F. W. Niven }}</ref> Other abnormal flooding events occurred in the winters of 1847 and 1860, while the most recent flooding occurred in 2017. Later events have since been assessed for their [[return period]].<ref name="miro05" />{{rp|p=102}}

The largest recorded flood event was in July 1872 which had a calculated return period of [[100-year flood|100 years]].<ref name="miro05" />{{rp|p=102}} At the Helena River, the 1872 flood level was {{convert|2|ft|3|in|mm|order=flip}} higher than the 1862 event with a return period of 60 years. An account in ''[[The West Australian#History|The Perth Gazette and Western Australian Journal]]'' on 26 July 1872 reported<ref>{{cite news |url=http://nla.gov.au/nla.news-article3752641 |title=Country News |work=[[The West Australian#History|The Perth Gazette and Western Australian Journal]] |date=26 July 1872 |access-date=13 September 2009}}</ref>
{{blockquote |text=In and about Perth, the water owing to the force of the incoming seas at the mouth of the river presented a scene of a great lake, all the jetties were submerged, the high roads to Fremantle covered, and passage traffic rendered impossible quantities of sandalwood lying along the banks of river were washed away, and the inhabitants of the suburban villas on the slopes of Mount Eliza obliged to scramble up the hill sides to get into Perth.}}

The flood of July 1926, with a return period of 30 years,<ref name="miro05" />{{rp|p=102}} resulted in the washing away of the Yagan Bridge and a section of the Fremantle Railway Bridge.<ref>{{cite book |last=Brearley |first=Anne |date=2005 |title=Ernest Hodgkin's Swanland: Estuaries and Coastal Lagoons of South-western Australia |publisher=[[University of Western Australia Press|UWAP]] for the Ernest Hodgkin Trust for Estuary Education and Research and [[National Trust of Australia (WA)]] |isbn=978-1-920694-38-8 |page=86 |quote=Re the 1926 flood: ''floodwaters spread over 5 kilometres at Guildford, and covered large areas of Perth Esplanade, and South Perth... and 12,729 million litres cascaded over Mundaring Weir'' |location=Crawley }}</ref> The Fremantle bridge partially collapsed on 22 July 1926, five minutes after a train containing schoolchildren had passed over.<ref>{{cite news |url=http://nla.gov.au/nla.news-article46532437 |title=THE WESTERN AUSTRALIAN FLOODS. |newspaper=[[The Advertiser (Adelaide)|The Advertiser]] |location=Adelaide |date=23 July 1926 |access-date=21 February 2012 |page=17 |publisher=National Library of Australia}}</ref> No one was injured in the collapse; however, it created major disruption to commerce for several months. Repairs were completed and the bridge reopened on 12 October 1926.<ref>{{cite news |url=http://nla.gov.au/nla.news-article31954082 |title=FREMANTLE RAILWAY BRIDGE. |newspaper=[[The West Australian]] |location=Perth |date=12 October 1926 |access-date=21 February 2012 |page=7 |publisher=National Library of Australia}}</ref>
{{gallery
|align=centre
|width=200
|height=140
|mode=packed

|title=1926 floods

|Mill Point, South Perth, 1926 floods.jpg
|Mill Point, South Perth, during the 1926 floods

|North Fremantle Railway Bridge collapse, 1926.jpg
|North Fremantle Railway Bridge collapse in 1926
}}
{{Clear}}