Instream Hydrodynamic and Water Quality Model for the Oldman River (Alberta, Canada)

DSI supported AESRI, Canada, to develop an instream hydrodynamic and water quality model of Oldman River. The Oldman River Basin, a sub-basin of the much larger South Saskatchewan River Basin, occupies an area of approximately 26,000 km2, of which 23,800 km2 are situated in Alberta. The watershed supports a wide variety of natural resources, including forests, minerals, wildlife, and agricultural lands. To support the delivery of the Cumulative Effects Management System and other key provincial initiatives and strategies including the implementation of the South Saskatchewan River Plan, address local water management issues and related water management measures, a water quality model for the Oldman River was developed to simulate historical and current hydrodynamic and water quality conditions in the river main stem and predict the future conditions under various water management practices. The Environmental Fluid Dynamics Code (EFDC) platform was selected for the Oldman River system by client as the use of this model application allows the evaluation of contaminant loadings, and their effect on river water quality, under various management and engineering options in sub-basin. Additionally, the dynamic water quality model is the basis for a toxic integrated model and scenarios of the Oldman River to support watershed and regional planning. DSI modified the EFDC code to provide an ice sub-model to better simulate the thermal behavior of the system in winter conditions. Constituents modeled included 2D depth averaged hydrodynamics, water temperature, dissolved oxygen, organic carbon, organic and inorganic phosphorous nutrients, organic and inorganic nitrogen nutrients, and planktonic algae. Along with the model and training in the user of EFDC and EFDC_Explorer tailored for this model, a report was provided documenting the configuration, calibration and sensitivity analysis of the river water quality model for the mainstem of the Oldman River from Lethbridge to the confluence with Bow River. The Oldman River EFDC water quality model was calibrated for the 2004-2014 period with good results. A sensitivity analysis was also performed. Water temperature, dissolved oxygen, phytoplankton, nutrient and phosphorous are well represented in the model. The model can be used as a tool for prediction of Oldman River hydrodynamic and water quality.