MODELLING GROUNDWATER-SURFACE WATER INTERACTIONS IN THE CANADIAN BOREAL REGION

Wetlands play a substantial role in the hydrological cycle as they interact with the surrounding upslope area through the lateral exchange of groundwater. Many hydrological models ignore the representation of the lateral water exchange between landscape features (e.g. wetlands and hillslopes) and consider only the vertical components. This can lead to inaccuracies in simulating the different components of the hydrological cycle. This study aims to simulate the upland-wetland interactions by focusing on fens, which are mainly fed by groundwater discharge. To represent the lateral water fluxes between uplands and wetlands, three different approaches are investigated. The three approaches represent the possible conditions of lateral water exchange between upland and wetland, which are no exchange (uncoupled), one-way exchange (chained), and two-way exchange (fully coupled). A 1-D physically-based model is used to reproduce detailed field observations and calculate the fluxes into and out of the fen. Three different versions of the model are developed to represent the three proposed approaches. Monte Carlo analysis is used to optimize the performance of the models and evaluate the uncertainty and identifiability in the results. The models are used to investigate the behavior of the system under different spatial configurations and help to understand when and where the inclusion of dynamic coupled interactions between upland and wetland is essential.