Integrated modelling of groundwater-surface water interactions in the boreal landscape

Understanding the interplay between groundwater and surface water is crucial for protecting valuable ecosystems, ensuring sustainable water supplies, and comprehending a wide range of biogeochemical processes. Despite their importance, the interactions between groundwater and surface water are still poorly understood due to challenges in their measurement. Doctoral researcher Anna Autio sheds new light on this subject by applying state-of-the-art, fully-integrated hydrological models to boreal landscapes, particularly focusing on groundwater-dependent ecosystems such as peatlands, lakes, springs, and streams.
“Only modelling can provide detailed information on dynamic spatial patterns of the groundwater-surface water interactions; field methods offer only a spatial snapshot or are limited to point locations” says doctoral researcher Anna Autio. “Modelling also allows us to study how these systems change under various management actions. This is why the ability to build high-quality integrated models is very important,” emphasizes Autio.
Autio’s research highlights both the potential and the challenges associated with these advanced modelling methods. Her simulations show that fully-integrated models can successfully reproduce approximately two-thirds of groundwater exfiltration locations identified using thermal camera imaging in a case study of Pallaslompolo, a small headwater catchment in Northern Finland. The model also accurately represents about 50% of locations determined using stable water isotopes, another common field technique in hydrological studies. The discrepancies between the model and field methods likely arise from a simplified geological model of the site, but may also reflect limitations in the field methodologies themselves.
Autio’s doctoral thesis delves into the model sensitivity related to peatland-mineral systems. In additional studies of the Kälväsvaara aquifer-Olvassuo aapa mire system and hypothetical conceptual scenarios, she demonstrates the multitude of factors affecting groundwater-surface water fluxes. In Finnish conditions, water-conductive glaciofluvial sandy soil deposits are prevalent, but the surrounding soil properties significantly influence hydrological dynamics and groundwater-surface water exchange. Moreover, the distribution of peat depth and terrain slope plays crucial roles in the emergence and spatial magnitude of groundwater-surface water interactions in boreal landscapes.
“Fully integrated models should be essential tools to investigate impacts at societally important sites, but we need more diverse datasets for model calibration and validation,” concludes Autio. “We must also learn how best to incorporate this additional information into our models to enhance their accuracy and reliability.”