PhD Research - Matthew Meyers

MESM, Water Resource Management, UCSB Bren School of Environmental Science & Management; BS, Earth Science, UC Santa Cruz

Matthew Meyers's research interests are focused on river management as it pertains to fluvial geomorphology and its application of hydrology and sediment transport toward aquatic ecosystem function. His research is tied to his work with California’s Department of Water Resources, where he serves as part of the river restoration group. This partnership allows data collection opportunities, among other things, focused primarily on the San Joaquin River Restoration Project and its goal of salmonid reintroduction in a minimal-flow environment. Matthew is responsible for predicting sediment transportability and channel change in this altered river system, thereby allowing exploration of the dynamics between hydraulics, bed texture, and sediment transport and their relationship with aquatic ecosystem dependencies. Immediate research findings are focused on modeling and field measurement of sediment entrainment thresholds and transport domains, sediment disentrainment thresholds, fine sediment accumulation in a gravel framework, and the evolution of bed texture and channel geometry.

Dissertation Abstract
The coarse texture of a gravel bed is maintained by flow strengths capable of moving (i.e., entraining) the gravel and removing fine sediments, thereby providing loose substrate that enhances its ability to conduct flow (i.e., its hydraulic conductivity). I examine these processes using field measurements to explain the variability in (i) the rate of change in the proportion of a gravel size fraction entrained as a function of flow strength and (ii) the rate of decrease in hydraulic conductivity as a function of the cumulative transport of fine sediment that depends on flow level. Two approaches are demonstrated to provide the flow strength capable of entraining the least resistant through the most resistant grains, thereby providing new methods to measure the flow strength that is capable of entraining a given fraction of the bed. Using artificially constructed salmon nests, the hydraulic conductivity of sediment mixtures is demonstrated to depend on fine sediment bed load transport as a function of flow rate. This work provides additional understandings of the relationship between flow and bed texture maintenance processes and useful tools for managing gravel bed rivers.

Year Admitted: 2008
Research Areas: Fluvial Processes, Sediment Transport, Physical Aquatic Habitat, River Restoration and Management
Faculty Advisor: Tom Dunne