Acoustic Gravel-Transport Sensor

Gravel streambeds and beaches provide spawning habitat for salmon and form barriers to coastal erosion. Understanding how gravel is transported through measurements is essential for monitoring the ecological and physical processes of gravel-bed systems and for calibrating sediment transport models. We propose Phase II research to develop: 1) impact-recording sensors that can be deployed by wading operators or from bridges (designated Type 1 devices)and autonomous, internally recording systems that can be deployed in streams, on beaches, or on talus slopes for weeks to months to capture continuous records of bedload transport (designated Type 2 devices), 2) a method to estimate mass and volume transport rates in gravel bedload from the particle momentum data recorded by acoustic instruments and water depth logged by an auxiliary pressure sensor, and 3) an embedded controller to compute and record momentum, mass and volume-fluxes and pressure in real-time. Successful completion of the project will result in two new field-tested and flume-calibrated instruments that are safer to operate, more efficient in terms of data recovered per operator-hour and sampling intensity, and are functional over a wider range of transport and flow conditions than can be sampled with existing methods.