Estimating Peak Runoff for Risk-Based Assessment in Small Catchments

Summary

The management and design of hydraulic infrastructure requires detailed analysis of the rainfall-runoff process, as well as the allocation of an acceptable level of risk. Risk-based assessment of the rainfall-runoff process requires methodologies that are both accurate and efficient. Although the Rational Method has been a popular analysis tool in risk based assessment, it has many short comings requiring significant subjective judgement by the engineer. Rainfallrunoff models have become increasingly popular in this regard, as they provide accurate tools to predict the deterministic processes taking place in the catchment. A methodology is presented in this paper for incorporating rainfall-runoff models in risk-based assessment that is both efficient in terms of computational effort and accurate. The method relies on the adoption of a storm pattern that embodies the characteristics contained within the statistically based rainfall data that is generally adopted in practice. The methodology has been tested on two hypothetical catchments and 47 small gauged catchments in Queensland. It is shown that using this methodology, statistically based peak runoff can be predicted at all locations in the catchment where suitable catchment subdivision had been undertaken.

Additional information

Notes on contributors

Graham A Jenkins

Dr Graham Jenkins is a Senior Lecturer in the School of Environmental Engineering at Griffith University in Brisbane, Queensland. He graduated with a Bachelor of Engineering (Hons) in Civil Engineering from the University of Newcastle in 1984. Graham graduated with a Ph D from the Department of Civil Engineering at Monash University in 1990. His research interests are in the development and use of computational hydraulics and hydrology in small catchments, particularly urban systems. He is particularly interested in the hydraulic characteristics of urban wetland systems and the relationship between the hydraulic characteristics and ecology of natural urban creek systems. Graham’s career has spanned both the private and public sectors of the water industry in Australia. His academic career includes over 12 years experience in lecturing hydraulics and hydrology at Monash University and Queensland University of Technology.

Ashantha Goonetilleke

Dr Ashantha Goonetilleke is a Senior Lecturer in Water/Environmental Engineering at the School of Civil Engineering, Queensland University of Technology. He holds a BSc (Hons.) Degree in Civil Engineering from the University of Sri Lanka, a Masters Degree in Environmental Management from Griffith University and a PhD from Queensland University of Technology. His research interests include urban hydrology, urban water quality, hydrologic modelling and GIS integration in hydrology. His career spans over seven years experience in lecturing in water and environmental engineering and over sixteen years experience in the planning, design and construction of internationally financed infrastructure development projects.

Robin G Black

Robin Black recently retired as Senior Lecturer in Hydraulic Engineering in the School of Civil Engineering at Queensland University of Technology. His design and research interests were in urban drainage, open channel hydraulics, engineering education and engineering heritage. Before QUT Robin spent five years with the then Irrigation and Water Supply Commission, Queensland. His duties were principally in design, operations and maintenance of irrigation works in Mareeba, Far North Queensland. Since retirement in 1999, Robin has been active in engineering heritage and is currently Chair of the Queensland Heritage Panel, and is an executive member of Engineering Heritage Australia.