EEPS Colloquium: Elowyn Yager

The importance of geomorphic and flow history: why preexisting conditions matter

Professor Elowyn Yager, University of Idaho Center for Ecohydraulics Research

A wide range of processes from long-term evolution of mountain ranges to complex interactions of vegetation, flow, and sediment involve the use of geomorphologic models.  In such models, the histories (e.g., sequences of flows) of a channel are often neglected either for the sake of simplicity or because little is known about preexisting conditions.  Here, we use a combination of field measurements and laboratory experiments to demonstrate the importance of channel histories at a range of spatial scales. We provide key examples that show these histories are integral to understanding and predicting geomorphic change.  We specifically focus on how different types of flow histories (flow hydrographs vs. surface water-groundwater exchange rates) directly and indirectly impact the deposition and release of fine sediment and associated nutrients from the streambed.  Neglecting the influence of these flow histories in geomorphic or sediment transport models results in large prediction errors that can impact river management decisions.

Host: Claire Masteller

EEPS colloquia are made possible by the William C. Ferguson Fund