Oil spill dispersion in freshwater under ice conditions: A pilot study of Lake Erie using coupled models.

Oil spills in ice-covered freshwater systems pose significant environmental risks, yet predictive modeling frameworks for such conditions remain underdeveloped. This study develops and validates a coupled modeling system integrating the General NOAA Operational Modeling Environment (GNOME) with the Great Lakes Operational Forecast System (GLOFS) to simulate oil spill dispersion under varying ice conditions. Lake Erie served as the study area, with model validation performed using observed drifter trajectory data. Six hypothetical oil spill scenarios were simulated across freezing, stable, and melting ice seasons from 2018 to 2022, comparing oil transport dynamics under ice-covered and open-water conditions. The results demonstrate that high ice concentrations during the stable season substantially restricted oil transport, reducing the oil-affected open-water area by limiting horizontal dispersion. A statistically significant inverse correlation was identified between initial ice concentration and oil spread extent, with this relationship being strongest during the first day post-spill. Risk mapping further revealed that ice cover functions as a natural barrier, confining oil accumulation near spill sources. These findings provide critical insights for emergency response planning in cold freshwater environments and establish a robust predictive framework applicable to other ice-prone freshwater systems globally.