Jamie Turner Thesis Proposal

Title: Effects on streamflow from changing snow fraction in a mountainous catchment

Abstract: In western North America, the proportion of annual precipitation that falls as snow– called the snow fraction– is declining. This has important implications for watersheds that rely on mountain snow storage for their water supply. As snow-dominated regions transition to becoming rain-dominated, the hydrologic response of those watersheds is expected to change as well. The direction and magnitude of changes, however, are unclear (Gordon et al., 2022). While there is significant evidence that a precipitation shift from snow towards rain leads to a decrease in outlet streamflow, it is not clearly established what effects on runoff efficiency and snowmelt timing are induced by these shifts (Berghuijs et al., 2014). Using a multi-decade hydrometeorological dataset from the long-term hydrologic observatory of the Reynolds Creek Experimental Watershed, we aim to investigate how the changes in runoff efficiency and snowmelt timing respond to declines in snow fraction over decades. The almost-60-year dataset will be used for modeling of the above metrics in the Cold Regions Hydrological Model (CRHM). Insight into possible mechanisms driving the relationship will be drawn from a sensitivity analysis of snow fraction and relevant hydrologic variables with available data.

Advisor: James McNamara

Committee Members: Lejo Flores, Andrew Hedrick