Hydrologic modeling and evaluation of Best Management Practice scenarios for the Grand River watershed in Southern Ontario

Abstract The Grand River is the largest river in Southern Ontario feeding Lake Erie with water, sediment, and nutrients. Understanding the watershed hydrological processes is crucial to support decision making on reducing non-point source pollution from the watershed into Lake Erie. In this study, the Soil and Water Assessment Tool (SWAT) was adapted to Canadian conditions and applied to the Grand River watershed in Southern Ontario to simulate hydrologic processes based on available geospatial, climate, management, flow, and water quality data. The SWAT was calibrated based on flow, sediment, and nutrient concentrations at eight flow gauging stations and seven water quality stations. The calibrated model was then applied to evaluate the potential effects of Best Management Practices (BMPs) including nutrient management, buffer strip, cover crop, and wetland restoration on water quantity and water quality in the watershed. The evaluated results showed that the BMPs of nutrient management and wetland restoration have more significant impacts on nutrient reduction at the watershed outlet to Lake Erie based on the BMP implementation and extent that were applied in this study. The SWAT modeling, findings, challenges, and recommendations for future research in the Grand River watershed are also discussed in this paper.