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Abstract

As the mining industry adapts to meet sustainability and environmental, social, and governance (ESG) goals in the face of climate change, water resiliency is one of the most critical issues. Ensuring adequate water management and treatment at a mine site is as critical as securing water for mining and processing operations. This is partly due to increasing water conflicts within a larger global water crisis, and also because stakeholders can increasingly revoke a mine’s social license to operate if it degrades local water quality or supply. Many current operating mines were built based on average conditions using deterministic water balance models and historic average data from the past century. The precipitation frequency data and statistics from historic records are no longer relevant, as new weather patterns forecast more periods of drought followed by extreme rainfall events of greater intensity than previously considered possible. One example of the significance of climate change is the drastic increase in the Federal Emergency Management Agency (FEMA) declared flood disasters in the United States (US). In 2000, there were only two flood disasters, but for the year through October 22, 2024, there were 66 flood disaster declarations in the US (Flavelle, 2024). Conversely, many operating mines in the southwestern US can expect to experience up to an 85% chance of a multi-decadal drought before 2100. Shrewd mine water managers, regulators, stakeholders, and consultants are adapting to this by developing stochastic water balance and water quality models that incorporate forward-looking climate change scenarios and anticipated changes in the mine site landscape to forecast possible, plausible, probable, and preferable impacts on both mine water quantity and quality management. The results often indicate water resiliency issues with adequate process water during periods of drought, deficiencies in stormwater management during heavy precipitation events, and deterioration in water quality that often requires additional treatment steps before discharge. The results from these models are then used to develop a more resilient and flexible water management plan that can adapt to and recover from any hydrological event. Updates to the water management plan may include adding or upgrading infrastructure, such as water collection ditches, retention ponds, and pumping stations, reprofiling existing landforms, adding a water treatment facility, and increasing surveillance of water levels, volume, and quality on site. This paper outlines recent methodologies for building forward-looking stochastic water balance and water quality forecast models that integrate climate change scenarios, water quality data, geochemical modelling results, and changes to the mine site over time that impact the water balance. Case studies and examples are also presented, showcasing how these models have been used to help mining companies develop more resilient water management plans and identify the work required to address these climate risks.