This project explores the processes and outcomes of river responses to both natural and human-induced changes in sediment supply to better develop predictive models of channel morphlogic adjustments and the mechanisms of sediment transport. Rivers reflect and respond to changes in streamflow and sediment supply striving to maintain equilibrium by mutually adjusting an array of channel properties. Yet, recent research reveals that the type and magnitude of these responses is conditioned in unknown ways by variations in sediment supply. The investigators will use stream reaches at and below existing/removed dams that decrease/increase sediment supply as an experimental design to capture these potential responses. With its focus on dams and dam removal, project outcomes will be relevant to watershed managers, especially as the nation?s existing dam infrastructure continues to age, posing significant environmental, social, and economic risks. This project will recruit diverse students from underrepresented groups. Through articles and presentations at conferences and public meetings, results will be disseminated to a broad array of scientists and regional stakeholders.
The overarching goal of this project is to quantify the channel morphologic evolution to transient and/or sustained changes in sediment supply and to demonstrate how morphologic evolution conditions hydraulic properties and subsequent sediment transport. The investigators will utilize a research design that is based on detailed geospatial field mapping and channel surveying combined with monitoring the mobility of gravel clasts tagged with radio-frequency identification (RFID) tracers and with embedded accelerometers to quantify the variation in bankfull hydraulic properties, threshold stream power, and bed architecture in response to changes (both positive and negative) in sediment supply. By taking advantage of the natural experiments provided by both dam emplacement and removal, the research will improve our understanding of channel evolution following a disturbance and thereby advance our theoretical understanding of fundamental river processes that can be applied in other geomorphic settings. The broadly disseminated results are essential for river restoration, with implications for both nature and society
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
