Rock chutes: a review of damage and failure mechanisms

Abstract

Rock chutes (also known as rock ramps and rock riffles) are an important technique for controlling erosion, and have been widely used in Victorian streams. Occasionally, for a number of reasons, they are damaged or fail. Based on a survey of 170 rock chutes in north east Victoria and Gippsland, eight damage or failure modes have been identified. These failure mechanisms include loss of rock from the face and crest, downstream erosion, undermining of the chute apron, stream bed instability, abutment damage, total loss of the chute and willow infestation. The greatest risk to rock chutes arises from three mechanisms, loss of rock from the face of the chute, willow infestation and abutment damage. It is important to consider the complete range of possible failure mechanisms when designing rock chutes. Improved design procedures are discussed which especially target the greatest risk to chutes, loss of rock from the chute face.

Keywords:

• Rock chutes
• stream restoration
• stream incision
• stream management

Additional information

Notes on contributors

Anthony R Ladson

Tony Ladson is a senior lecturer in the Department of Civil Engineering and a member of the Institute for Sustainable Water Resources at Monash University. He is also an honorary fellow in the School of Anthropology, Geography and Environmental Studies at the University of Melbourne. His research interests include developing and testing methods to assess the condition of streams and approaches to their restoration. He has worked in the field of environmental flows and has a long-term interest in the management of the Barmah-Millewa Forest. Tony teaches undergraduate and post graduate courses in hydrology, hydraulics, flood management and water resources management.

Ross E Hardie

Ross Hardie is one of Australia’s leading waterway management practitioners with more than 18 years direct experience in the waterway management industry. Ross has a particular interest in the investigation and management of incised stream systems including the implementation of grade control and channel roughness strategies incorporating rock chute style structures in combination with vegetation establishment. This interest has also led to the review of failure mechanisms for such programs and the development of parameters and criteria for the hydraulic design of incised stream management works.

Robert J Keller

Bob Keller works in the fields of river engineering, hydraulic structures, and computer and physical modelling of rivers and floodplains. Bob worked in the river restoration program of the Cooperative Research Centre for Catchment Hydrology where he developed CHUTE a computer based aid for the design of rock chutes.