The influence of highway-stream crossings on stream temperature, aufeis, and terrain dynamics in continuous permafrost

In permafrost regions, road construction alters the ground thermal regime and hydrology, with implications for permafrost and infrastructure. This paper examines the hydrothermal and terrain effects of highway bridges and culverts on small streams in continuous permafrost in the western Canadian Arctic near Inuvik, Northwest Territories. Along the Inuvik to Tuktoyaktuk Highway, stream-crossing structures modify channel configuration, material properties, and boundary conditions, accelerating streambed freezing, impeding flow under bridges, and forming ice plugs in culverts. Coupled with prolonged winter baseflows, we demonstrate that these conditions produce elevated hydrostatic pressure upstream of the structures leading to the formation of aufeis, injection ice, and significant perturbations to riparian areas. Dynamic pressure-driven processes in a freezing hydrological system also impact structures through the heaving and subsidence of adjacent natural and engineered streambanks and culverts, the icing of road surfaces, scour beneath bridge structures, or washout of aggregate road embankments during freshet when channels or culverts remain ice-filled. We demonstrate that rapid freezing promoted by roads and structures drives complex interactions between winter stream flow and infrastructure, highlighting the importance of interdisciplinary perspectives and robust monitoring systems to evaluate infrastructure performance and inform mitigation and engineering innovations in a changing permafrost environment.