Assessing risks of returning mined land to grazing in the Bowen Basin of central Queensland, Australia

Abstract

Regulation of mining in Queensland, Australia requires completed rehabilitation to result in the site being safe, stable, presenting no adverse off-site impacts and for a sustainable end use acceptable to stakeholders to be designated. By 2008, an estimated area of 70,000 ha of the coal-mining region of central Queensland had been disturbed by mining activities of which some one third has been rehabilitated. The remaining notional accrued rehabilitation liability exceeds A$1 billion. Rehabilitation of mined land in central Queensland is performed by re-contouring spoil heaps to reduce slope angles, applying a layer of topsoil, and planting various combinations of pasture grasses, shrubs and trees. Approximately half of the rehabilitated areas have been revegetated using bushland species native to the region and half to exotic pasture species suited to cattle grazing. Vegetation cover is valuable in protecting the soil surface from the erosive forces of the often-intense summer rains that occur in the region. Where pasture productivity is high, there is sufficient vegetation both to protect the soil surface and to support grazing. This outcome has been demonstrated both theoretically and in small-scale trials. However, inappropriate grazing management (overgrazing) may reduce the amount of vegetation cover below that needed to protect the soil. The style of land management practised by the manager of the cattle is therefore critical to the sustainability of grazing as an end use. This paper reports on research into the management style likely to be used by the region’s graziers if granted tenure of mined land. Graziers’ management style was modelled as being influenced by their characteristics and circumstances. The chief influences were found to be: • The financial stability of the grazier’s business (25%). • The effect of interventions that a company may take; for example, building respectful, trusting relationships with graziers (23%). • Graziers’ non-financial motives in seeking tenure of mined land (17%). • Graziers’ underlying rural values and attitudes to land management (14%). • The property’s operational flexibility (12%). • The external climatic and economic environment (9%). An understanding of factors that influence the grazing management of mined land can be used to assess risks, suggest interventions to reduce grazing risks, to guide the planning of future rehabilitation work, and to support a company's end use proposal to the regulator.