University Of New South Wales

1397 WordsMay 22, 20166 Pages
University of New South Wales CVEN9611 –Urban Hydraulic Structures Assignment Stefan Felder Submitted by: Garth Cooper Student Number – z3189074 Question 1 Toowoomba City is located 125km from Brisbane in Queensland on the Western side of the Great Dividing Range. It consists of two main creek catchments, east creek and west creek catchments. In January 2011 there was a main flooding event which caused a large flood event that is described as an “Inland Tsunami”. Figure 1 - Catchment map of Toowoomba identifying major hydraulic features. Source [1] The factors that contributed to the major storm was: • There was an initial rainfall even of 90mm which occurred over 24 hours before which caused the catchments to be fully saturated. As a result any major rainfall events would be converted directly into surface water runoff • Most of the catchments depicted in Figure 1 where fully urbanised which caused surfaces in the catchment to be impervious; that is very little runoff would infiltrate into the ground • There were intense rainfall events that occurred over the Gowrie creek catchment; with an event greater than a 100 year ARI storm experienced at the rainfall gauges • Due to the large intensities of rainfalls caused both East and West creeks to fill up. Due to both creeks flowing in the same direction no drainage could occur to Gworiee creek causing inundation shown in Appendix Figure 2 - Recorded Maximum rainfall intensities and Serveries in Toowoomba, 10
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