Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-04-30
Total Federal Funds: $35,000 Total Non-Federal Funds: $70,000
Principal Investigators: Karen Prestegaard, Vedran Lekic
Abstract: River characteristics (width, depth, velocity) are built by turbulent water flow that erodes and deposits sediment. Turbulent eddies are formed as water flows over particles on the channel bed. Turbulent dissipation of energy also results from larger features, such as riffle-pool sequences, river meanders, and channel bars. These morphological features are essential habitat niches for aquatic life and they generate about half of the total flow resistance in rivers. Morphological complexity of rivers contributes to the inherent spatial temporal variability in river processes, including sediment erosion and deposition. Spatial variations in velocity, shear stress, and turbulence causes variability in sediment transport rates, but it is difficult to measure these parameters in rivers. It is even more difficult to measure them simultaneously at many locations. Turbulence, however, generates seismic noise that can be measured with geophones and hydrophones. Preliminary research indicates correlations between near-bed velocity and seismic noise in rivers. The purpose of this project is to develop seismic techniques to determine near-bed velocity, turbulence, and basal shear stress in alluvial bedrock rivers. Coupled seismic and velocity measurements will be made in at 20 locations in river reaches near USGS gauges. Measurements will be made over a range of flow conditions and compared with theoretical models of turbulence generated by bed particles to characterize both boundary-generated turbulence, and morphology-generated turbulence in alluvial and bedrock channels.