Grazing as a post-mining land use: A conceptual model of the risk factors

Driven principally by government regulation and societal expectations, mining companies around the world are seeking to mitigate the environmental impacts of mining through mined land rehabilitation programs. The ultimate goal of rehabilitation is to establish an acceptable and sustainable post-mining land use. Mining companies worldwide face the challenge of specifying just what a sustainable post-mining land use will be. The problem is that while regulations require mining companies to assess post-mining land use sustainability, the mechanism for doing so and the factors that should be considered are not specified. We propose a risk-based approach to post-mining land use assessment with the aim of reducing the uncertainty of mine closure and the potential cost of repair of land degradation caused by inappropriate post-mining land use. Grazing is a commonly suggested post-mining land use, particularly in Australia where most mining activities occur on land previously used for cattle grazing. Grazing is also seen as a use suited to rehabilitated mined land because of the lower land productivity required compared to cropping. In this paper we develop a conceptual model of the factors influencing the land degradation risk posed by grazing on rehabilitated mined land. This was done through a literature review to identify potentially important risk factors, followed by a survey of graziers surrounding six open cut mines within the Bowen Basin Region of Queensland, Australia. The survey results were used to develop a profile of the risk factors likely to influence the land management behaviour of graziers within the Bowen Basin. The results of the research highlight that there are three main sets of factors that affect grazing risk on rehabilitated mined land. These are site biophysical characteristics that influence land productivity and commercial grazing viability, factors that influence the land management style of a grazier (principally stocking rate decisions), and factors that influence the commitment of a grazier to comply with any caveats placed on the management of the land. The profile of risk factors obtained for Bowen Basin graziers showed that grazing is likely to be a low risk post-mining land use where land productivity is high enough to support commercial cattle grazing and where land is managed by local graziers. Both the conceptual model and the profile of risk factors described in this paper are precursors to the development of a predictive risk assessment model.