Fluid Mud Study in Canada's Petitcodiac River

As part of a project aimed at understanding the influence of high-concentration suspensions of fine sediments (fluid muds) on flow, researchers from Boston College and the Bedford Institute of Oceanography recently deployed a SonTek Autonomous ADV (Hydra) in the Petitcodiac River, New Brunswick, Canada (pictured left).

The Petitcodiac was chosen because of consistently high suspended-sediment concentrations (0.5 to >200 g/L) and large tidal range (>4 m) producing strong current velocities (> 1.5 m/s). The Hydra was mounted on a tripod and lowered from a bridge into the Petitcodiac River obtaining flow and turbulence measurements within fluid muds and the overlying water column.

The Hydra was chosen for its robust configuration and ability to collect high-frequency (25 Hz) three-dimensional velocity data in a remote sampling volume. Additionally, it measures the distance to the boundary, which can be used to monitor morphological changes to the bottom. The resulting data set provides an excellent means to test threshold conditions regarding suppression of turbulence by sediment-induced stratification and the carrying capacity of turbulent flows.

• Hydra