Schmidt, Jack; Leonard, Christina; Jukes, Thomas (Utah State University)
Faculty Advisor: Schmidt, Jack (S.J. & Jessie E. Quinney College of Natural Resources, Watershed Sciences Department)
Abstract: Western rivers are impounded by a suite of water resource infrastructure that supports human life and has fueled western development. These rivers also support a unique ecosystem for endemic endangered species, whose habitat has been degraded by water resource development that has disrupted the flow and sediment delivered to the system. Channel morphology, and within-channel habitat are the consequence of sediment deposition and erosion. One way to measure the amount of sediment deposition or erosion is by measuring the amount of sediment transported into and out of a river segment to calculate the mass-sediment budget. Such analyses, however, cannot identify the locations within the river segment where aggradation or degradation has occurred, or predict how habitat has changed. In this study, we aim to correlate field-based measurements of channel and habitat change with flux-based sediment budgets. We propose that in order to predict detailed channel response and habitat change, flux-based sediment budgets must be partitioned by grain size class, because different grain size classes are eroded and deposited in different parts of the channel. As part of this study, we have collected samples and observations throughout the study area to analyze and characterize the grain size distribution of the channel and floodplain in units identified as eroding or aggrading. By obtaining information about where different grain size classes of sediment are deposited and eroded, we are working to link the partitioned mass-sediment budget to channel change to understand where and why channel change occurs.