Potential for mine water sharing to reduce unregulated discharge

Australia's mining sector periodically suffered huge losses both directly and indirectly from mismanagement of mine water during extreme climatic events. Mine water managers still lack cost-effective tools and strategies to manage both climate-influenced drought and flooding challenges. This paper aims to answer a fundamental question in mine water management: how much can a water sharing approach do to reduce unpermitted (unregulated) mine-affected water to overflow to the environment on a regional scale? To this end, we built a climate-driven hierarchical systems model (C-HSM) of sixteen coal mines in the Bowen Basin of Queensland, Australia. The C-HSM simulated the dynamics of the mine water systems, which was then the basis to assess the potential of mine water sharing to reduce unregulated discharge. We found that mine water sharing could greatly cut down regional unregulated discharge during the 2010-2011 wet season (which included an extreme flooding event). The cost of building such a regional-scale sharing infrastructure for redistributing water was found to be competitive to the lost revenue due to reduced coal production. The capital cost could potentially be further reduced by using existing water pipelines - such as those used for coal seam gas water management - or considering cheap transporting options. Once the sharing infrastructure has been installed, it can prevent periodic suffering of mines from climate extremes. Combined with an actively regulated discharge strategy, the water sharing approach could almost completely eliminate the unregulated discharge and maintain mine water storages at a secure level. The capital and operational cost for the combined approach can be considerably reduced and the shared water could be stored at other sites (mines, water holding ponds from coal seam gas industry) and used for water-limited periods. This is the first work that explores the theoretical potential of mine water sharing to mitigate the risk of unregulated discharge. The work presented here reveals that mine water sharing could help mine water managers respond to a sudden change in extremes such as switching from extreme 'dry' to extreme 'wet' conditions. A combined mine water sharing strategy would be worth considering by mine water managers, due to its advantages in regards to safety, relatively lower implementation costs, its effectiveness of reducing unregulated discharge that may cause environmental harm and conserving excess water for future water-limited periods. The ultimate value of water savings through a sharing scheme may be considerable as it influences mining industry's social license-to-operate in the long term, especially under conditions where there is a water security issue of decreasing availability and increasing competition. The work also highlights the benefits of systems modeling in supporting mine water managers with strategic decision making.