Conceptual Model Development for Transport and Fate of Oils Sands Process-affected Water (OSPW)

摘要

This paper presents a conceptual representation of mechanistic watershed processes to enhance the current watershed models for oil sands ecological risk management in Alberta. Phase 1 work of this multi-year model development applies a holistic approach to develop OSPW-Transport-Transformation-Vegetation (OTTV) Continuum conceptual framework that maps out OSPW sources, pathways and targets and the relevant interactive feedback processes. The OTTV conceptual model addresses two primary environmental issues that have typically been resolved in the past through the use of conservative environmental assessment assumptions. The first issue addresses the potential risk of the OSPW migrating from the tailings structure to downstream natural systems and negatively impacting the ecological health of the media of exposure. The second issue is related to recreating the boreal forest on tailings and sodic overburden deposits exposed to numerous natural and anthropogenic stressors during the reclamation process. Seven key gaps are addressed during the OTTV conceptualization, including (1) northern climate and hydrology; (2) natural and anthropogenic stressors; (3) surface/subsurface water and vegetation interactions; (4) upland boreal forest dynamics; (5) biogeochemical transformation; (6) water dynamics in tailings deposits; and (7) long-term soil cover and vegetation changes. These enhancements are critical to understanding cause-effect relationships and enhancing prediction of long-term water quality and reclamation success of oil sands mining. The OTTV future model will be generic in its ability to predict effects from any oil sands mine. The ultimate goal is to construct an integrated hydrological, hydrodynamic, water quality and vegetation modeling system capable of predicting the probability of substances in OSPW reaching ecological risk threshold concentrations in an exposure media of target. The model will also predict the trajectory of establishment of vegetation on reclaimed landscapes. The generic, but holistic, nature of the OTTV model will also support the assessment of OSPW risk scenarios, environmental monitoring, assessment of watershed integrity for any management scenario, and identification of the best management practices to mitigate and reclaim disturbed oil sands landscapes.