Hydrological and hydraulic investigation and floodway design at willare crossing of the fitzroy river - Western Australia

The great northern highway crosses the fitzroy river in the kimberley region of Western Australia at willare where the floodplain is 10.60 Km wide and the catchment area is 85,000 sq km. In 1985 the crossing was upgraded at a cost of $8.9 Million to pass the estimated 100 year flood of 10,200 m**3/s by constructing two new bridges and improving three existing floodways. In 1986 a rare flood event in the fitzroy river peaked at 17,500 m**3/s at willare and caused considerable damage to the crossing. This exceptional flow outflanked the protected sections of the crossing and scoured levee banks, guide banks and road embankments. Some failures at the downstream rock mattress protection were observed relatively early during the flood event and this indicated an inherent design weakness in the downstream shoulder of the rock mattress protection. A hydraulic model test was carried out at the centre for water research at the university of Western Australia. These tests indicated an area of negative pressure at the edge of the downstream shoulder of the floodways and identified certain hydrodynamic forces acting on the surface of the floodways. To improve the design, the downstream batter slope of the floodway was flattened from 2:1 to 3:1 and the edge rounded to a smooth curve of 3 m radius. The location of the joint of the rock mattresses with the concrete slab at the edge of the floodway was positioned well clear of the low pressure zone. To improve the waterway capacity of the crossing, floodways were lengthened and protected up to the 1986 flood level. All levee and guide banks were raised above the 1986 level to prevent lateral flows. The reinstatement work was completed at a total cost of $4.5 Million (a).

• Record URL:
  http://arrbknowledge.com
• Authors:
  • Van kleef, H
  • Goh, J
• Conference:
  • Australian Road Research Board (ARRB) Conference, 14th, 1988, Canberra
• Publication Date: 1988

Language

• English

Media Info

• Pagination: 32-40
• Monograph Title: Thermal loadings for South Australian bridges
• Serial:
  • Volume: 14
  • Issue Number: 6

Subject/Index Terms

• TRT Terms: Bridge design; Bridge management systems; Collapse; Cross sections; Floods; Hydrology; Performance
• ATRI Terms: Bridge design; Bridge failure; Bridge maintenance; Cross section; Flooding; Hydrology; Performance
• Subject Areas: Bridges and other structures; Hydraulics and Hydrology;

Filing Info

• Accession Number: 01429752
• Record Type: Publication
• Source Agency: ARRB
• Files: ATRI
• Created Date: Aug 24 2012 3:35PM