Design Flood Estimation with Consideration of Structure Blockage

James Ball, Bill Weeks, Mark Babister, Monique Retallick

Tuesday 30 june 2015

11:15 - 11:30h at South America (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flood risk assessment

Parallel session: 5J. Floodrisk - Assessment

While previous editions of ARR have served the Australian engineering profession as the primary primary guideline for flood estimation, a number of issues have necessitated the production of a new edition. These issues include the many recent developments in knowledge about rainfall-runoff processes, the increased computational capacity available to engineering hydrologists, and the rapidly expanding body of information about climate change. As part of the development of the new edition, existing approaches presented in ARR have been carefully reviewed considering both international and Australian practice, recent research and on-going data collection. Arising from this review, it has become apparent that the influence of blockage at structures on the design flood levels upstream of the structure and on design flood flows downstream of the structure has been neglected. Review of international practice has shown that the situation is similar elsewhere. An overview of the analysis and consultation used to develop a practical procedure and the risk based approach to including the influence of blockage of cross drainage structures will be presented in the proposed paper. These new procedures have been tested in a wide range of environments around Australia and provide a pragmatic, consistent and realistic methodology.