Simulating the cumulative effects of potential open-pit mining and climate change on streamflow and water quality in a mountainous watershed

• Published in: The Science of the total environment Vol. 806; p. 150394
• Main Authors: Chernos, M., MacDonald, R.J., Straker, J., Green, K., Craig, J.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2022
• Subjects: Hydrological modelling; Oldman River; Risk assessment; Selenium; Water management; Hydrological modelling; Water management; Selenium; Risk assessment; Oldman River
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.150394

Land use and climate change effects on water quality and water quantity are well documented globally. Most studies evaluate individual factors and effects, without considering the interrelationships between land use, climate, water quality, and water quantity. This study provides an integrated assessment of the cumulative effects of climate change and potential open-pit coal mining on streamflow and water quality in the Oldman River Basin, Alberta, Canada. A hydrological model was developed that incorporates estimates of future selenium loading, water use, and projected changes in air temperature and precipitation to evaluate changes in water quantity and quality. Model results indicate that estimated selenium concentrations, absent any attenuation, are likely to be substantially above most water quality guidelines and strong reliance on mitigation technologies would be required to maintain adequate water quality in the watershed if mine development were to take place. Streamflow is sensitive to changes in climatic conditions, and modelling results suggest there are likely to be increases in winter flow, earlier peak flow, and reductions in flow during the summer and fall months under the climate change scenarios. These changes can have direct impacts on the degree of selenium dilution and more generally on aquatic habitat, ecosystem health, and socioeconomic needs. This study highlights that water management decisions may mis-evaluate the risks and tradeoffs of future mine development if they fail to adequately consider climate change and changing streamflow regimes and their indirect effects on water quality. [Display omitted] •A hydrological model incorporates selenium loading, water use, and climate change.•Streamflow is sensitive to changes in climate and impacts selenium dilution.•Absent attenuation, selenium concentrations exceed most water quality guidelines.•Water management decisions should consider changes in climate and streamflow regimes.