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Abstract

Mine water management systems in northern latitude and high-elevation areas must be designed to withstand floods caused by snowmelt events (snowmelt-only and rain-on-snow) in addition to rain-only events. The effects of climate change on these events, over both operational and post-closure timescales, are important to consider. Snowmelt events often govern hydrotechnical designs in Canada; however, estimating snowmelt in a changing climate is complex and lacks guidance. Underestimates of design floods present a considerable risk for mines; overestimates can result in significant costs and other unintended impacts. The impacts of climate change on short-duration (1-day) snowmelt events have been evaluated by the author for five case studies across Canada in a previous paper. Design events for conveyance structures are typically short-duration events. Longer duration events, with larger volumes, are critical for facilities that are designed to store and actively manage the inflow design floods (IDFs) or environmental design floods (EDFs). This paper describes the potential impacts of climate change on long-duration snowmelt events and impacts on mine water management for four case studies in British Columbia, Alberta, the Northwest Territories, and Ontario. This paper builds on previous work by the same author (Clark & Whitmore., 2024), which established a method for evaluating the impacts of climate change on snowmelt events. The method evaluates climate change impacts using a continuous simulation snowmelt model and downscaled Global Climate Model (GCM) data to quantitatively model the joint probabilities of snow cover, warm temperatures, and rainfall coinciding (and future changes to these probabilities). While the results of this paper are site-specific, the extended geographic range of the case studies can help inform mine owners on the potential range of impacts of climate change on long-duration snowmelt events and potential impacts on mine water management. Using a continuous simulation model helps reduce the uncertainty in quantifying the potential impacts and helps design resilient, future-proof facilities and systems.