- Title
- Major floods - random or irregular?
- Creator
- McMahon, Greg; Kiem, Anthony S.
- Relation
- 37th Hydrology and Water Resources Symposium (HWRS 2016). Proceedings of the 37th Hydrology and Water Resources Symposium (HWRS 2016) (Queenstown, New Zealand 28 November - 2 December, 2016) p. 319-326
- Publisher
- Engineers Australia
- Resource Type
- conference paper
- Date
- 2016
- Description
- Flood frequency analysis as a methodology assumes that flood events are randomly distributed. As the understanding of weather has developed into ocean scale and world systems, the notion of regularity of systems has come into evidence. Most discussions of this genre have been with respect to drought, but some interesting observations have also been made with respect to flood events. This paper examines the data on flooding within the ten major catchments comprising more than 63,000 square kilometres bounded by three mountain ranges in South East Queensland (SEQ). The aim was to test the existence and strength of any regularity to flooding in this well populated region of Australia. The basic approach was to identify the flooding that occurred during predetermined five year periods that were thirty-five (35) years apart - the forty year flood cycle - and the flooding that occurred outside of these nominated 5 year periods. The basic statistics were weighted for the length of flood record, catchment area, ranking of flood, and a combination of these factors. The results indicate that 75-91% of major floods in SEQ have occurred within a set of five year periods exactly 35 years apart. This is consistent with independent studies that have reported 20-40 year flood cycles for coastal eastern Australia and inland New South Wales. Based on insights from these studies an explanation for the apparent 'forty year flood cycle' in SEQ flooding is proposed. From this an alternative or supplementary approach to describing the frequency of flooding is described.
- Subject
- flood frequency; flood cycles; flooding; Australia
- Identifier
- http://hdl.handle.net/1959.13/1345977
- Identifier
- uon:29754
- Identifier
- ISBN:9781922107954
- Language
- eng
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