THE MANAGEMENT OF GRAVEL EXTRACTION IN ALLUVIAL RIVERS: A CASE STUDY FROM THE AVON RIVER, SOUTHEASTERN AUSTRALIA

Abstract

A case study of the Avon River in Gippsland, southeastern Australia, demonstrates the impacts of commercial sand and gravel extraction from alluvial rivers. The Avon River has a long history of channel instability related in part to its recent change of course by avulsion and in part to destabilization driven by human activities in the channel. Contributing to this destabilization has been the extraction of gravel, which occurred over most of the past century and, in recent years, at a rate of at least 50,000 m1/yr. Analyses of the gravel and the material comprising the banks of the river indicate that the gravel is being replenished from bank erosion rather than from supply from the catchment. Catchment supply is estimated to be only 5000 m3/yr. While this estimate of the annual bedload transport rate may be useful for indicating that gravel extraction rates are not sustainable, it cannot be assumed that extraction at the annual bedload transport rate will result in minimal impact on an alluvial river such as the Avon. Both past and present legislation has allowed management and monitoring of gravel extraction. However, in practice, the ways in which government agencies have applied the legislation have led to largely uncontrolled gravel mining primarily because of a lack of political determination to enforce the regulations. It is concluded that responsibility for the management of gravel extraction should be in the hands of the agency with direct responsibility for management of the river, and that extraction should be allowed only where it is necessary to fulfil management objectives for the river and not for routine resource access. [Key words: natural resource management, river management, gravel extraction.]