Why should models talk to each other? A multipronged modelling strategy as an operational framework to guide adaptive watershed management in the Bay of Quinte Basin, Ontario, Canada

Environmental modelling has been one of the pillars of the adaptive watershed management process. It provides a way for scientists, managers, and other stakeholders to assess the existing understanding of the managed system and the knowledge gaps we seek to answer through monitoring and research. However, current watershed modelling and restoration efforts often fail to consider the role of different sources of aleatory and epistemic uncertainty surrounding the effectiveness of management practices. Estimating effectiveness is difficult because of poor spatial delineation of nutrient “hot-spots” at the regional planning level, misrepresentation of critical hydrological and biogeochemical processes at the watershed level, and several unaccounted factors operating at the individual farm or field levels, among others. Here, we outline an ongoing multi-pronged modelling approach for the Bay of Quinte that has been supporting the management in the area over the last ten years with the active participation of local stakeholders. The framework encompasses (i) regional assessment of high risk for nutrient export in time and space using mass-balance and semi-empirical nutrient loading models, (ii) mechanistic representations of watershed processes, and (iii) process-based representations of field dynamics. We summarize the key results from more than a dozen of research projects in that region and propose a coherent approach to integrate the information provided by them to improve modelling and monitoring. This framework specifies questions, methods, and data requirements relevant to each of its components, and the way they complement each other. This experience can provide a blueprint for adaptive watershed management worldwide.