Seasonal Influences on Hydrologic Anomalies in Headwater Catchments
Date:
Abstract: The Western United States relies on water from snow-fed mountain catchments, but hydrologic anomalies, where observed water volumes differ widely from predictions, have become increasingly pervasive in recent years. Researchers have developed many hypotheses to account for the causes of these anomalies, but they have not reached a consensus on which hydrologic processes are most important to explain them. In this dissertation, we address these anomalies by exploring how different seasonal components of the alpine water balance influence headwater basin hydrology. Here, we define the alpine water balance as the balance between streamflow, precipitation (snow + rain), evaporative losses (sublimation + evapotranspiration), and subsurface storage.
In chapters 1 and 2, we will focus on constraining uncertainties in two components of the alpine water balance that contribute to substantial variability in hydrologic models: wintertime sublimation and seasonal precipitation. In chapter 3, we will use an iterative modeling approach to determine which spatial and subsurface representations are most important to reduce hydrologic model uncertainty. In chapter 4, we apply the model architecture we developed to explore the physical mechanisms that connect fall and spring weather conditions to spring runoff anomalies. Together, these chapters explore individual components of the alpine water balance through the lens of seasonal variability in order to identify key contributors to hydrologic anomalies.