Investigation of design rainfall temporal patterns in the Gold Coast region of Queensland

Abstract

Design rainfall temporal pattern is a major source of uncertainty in rainfall-based design flood estimation methods. The Australian Rainfall and Runoff 1987 (ARR87) adopted the Method of Average Variability to derive design rainfall temporal patterns for Australia. It is assumed that the use of these temporal patterns along with representative values of other inputs to the rainfall runoff modeling can preserve the frequency of input rainfall depth in the final flood peak estimate. Although this assumption is questionable, the use of more holistic approach of design flood estimation such as Monte Carlo simulation technique or continuous simulation has not yet been widely accepted by the industry. It will take a while to develop design data and application tools for application with the Monte Carlo simulation and continuous simulation techniques and hence the ARR87 design temporal patterns will remain in use with the Design Event Approach for a while. This paper presents a simple windows-based tool that can be used with sufficient ease to derive design temporal patterns from region-specific data of longer lengths adopting the Method of Average Variability, the ARR87 procedure. This windows-based tool is applied in the Gold Coast region in Queensland to derive new design temporal patterns and it is found that the ARR87 design temporal patterns for the Gold Coast region result in significantly smaller estimated design floods for larger duration storms as compared to the newly derived design temporal patterns.

Keywords:

• Flood estimation
• temporal pattern
• design floods
• Design Event Approach

Additional information

Notes on contributors

Ataur Rahman

Ataur Rahman is a Senior Lecturer in Water and Environmental Engineering in the School of Engineering, University of Western Sydney. He has over 18 years experiences in water industries, research and universities in Australia and South-east Asia. He obtained his BSc Eng degree from Khulna University of Engineering and Technology in Bangladesh, MSc (Hydrology) degree from National University of Ireland Galway and PhD degree in Hydrology from Monash University. His research interest includes flood hydrology, urban hydrology and environmental risk assessment. He received the G. N. Alexander Medal from the Engineers Australia in 2002.

Mazharul Islam

Mazharul Islam is a Software Developer in Infomedia Ltd in Sydney. He has over eight years experiences in research, software analysis, design and development for clients in Australia, USA, Europe and South-east Asia. He obtained his B. Sc. Eng. degree in Computer Sciences and Engineering from Khulna University in Bangladesh. His professional interests includes enterprise development, advanced .net technology, service oriented architecture (SOA). He has been a Microsoft Certified Solution Developer (MCSD) since 1999.

Khondker Rahman

Khondker Rahman is an Executive Coordinator of Environment and Infrastructure Unit with the Strategic and Environmental Planning and Policy Branch of Gold Coast City Council. He has over 23 years of experience in water industries and local government authorities in Australia and overseas. Khondker’s main area of interest in Flood Management, Water Resources Planning and Development and most recently, Climate Change Impacts and Integrated Urban Water Cycle Management. He obtained his BSc Eng (Civil) from the Chittagong University of Engineering and Technology in 1983 and MEng (Water Resources) from the Asian Institute of Technology in 1986.

Sayed Khan

Sayed Khan is working as the Coordinator Planning Services of Gold Coast Water, Gold Coast City Council. He is a Water Resource Engineer with 18 years of professional experiences in water industries in the areas of hydrologic and hydraulic modelling, floodplain management, stormwater management, water resources planning, water supply and sewerage planning and development of policies and strategies in the local government water management arena. He obtained his B.Sc. Eng. degree from Bangladesh University of Engineering & Technology, M.Sc. degree from Asian Institute of Technology Thailand. Sayed’s current role in Gold Coast Water has the responsibility of sustainable management of water supply, recycled water and sewerage services through development of integrated urban water management strategies and waterfuture strategies.

Surendra Shrestha

Surendra Shrestha is an engineering hydrologist with both ground and surface water modelling experiences. Surendra has worked with multi-disciplinary research teams in Australia, Nepal and the USA. Over the years, his research involvement has been with teams conducting research on topics ranging from urban hydrology to forested hydrology to groundwater contamination & remediation. More recently, his involvement has been with academics, researchers and engineering professionals in mathematical modelling of the built urban environment. Recipient of the Colombo Plan Scholarship (1976–1981) for his undergraduate studies and East-West Centre Internship (1983–1985) for his post-graduate studies, Surendra completed his PhD in Civil Engineering from Virginia Polytechnic Institute and State University in Blacksburg, Virginia, USA. He is currently the Associate Head of School within the School of Engineering at the University of Western Sydney and is the Fellow of the Civil College of Engineers Australia. He is also a member of the American Society of Civil Engineers and the American Geophysical Union.