Snowpack to Streamflow: The Role of Snow Water Equivalent in Shaping Runoff Timing and Volume in the Lake Superior Basin

The Laurentian Great Lakes comprise the world's largest surface freshwater system. Over the past two decades, water levels in the great lakes have experienced significant fluctuations, reaching both record highs and lows. Accurate water level forecasting is critical due to the extensive ecosystems and large human populations that rely on this valuable resource. One critical variable in water level forecasting is surface runoff, which is directly impacted by precipitation amount and type in the basin. Lake Superior receives a considerable amount of snowfall annually, affecting both the timing and quantity of runoff into the Great Lakes system. Variations in the annual snow have led to changes in runoff patterns, potentially impacting the overall water levels of the Great Lakes. In this study, we analyze the patterns of snow water equivalent and their effects on surface runoff using the Large Basin Runoff Model (LBRM). Our results uncover a notable change in patterns of snow water in the 1970s and in runoff in the 1980s. Understanding these relationships is crucial for improving the accuracy of water level forecasts and preparing for future changes.