Littoral Drifter for Sensing Properties of Shallow Waters and Sediments: Riverine Drifter Field Trials July 10, August 13 and September 10, 2008

Abstract : Shallow water environments that exist where rivers and estuaries meet the ocean are often characterized by regimes of energetic currents and shallow rapidly varying bathymetry which in the case of easily mobilized sediments can by spatially modified over short periods. The Riverine drifter has the observational tools to measure the characteristics of the estuarine environment. It combines the position accuracy of GPS locations, 3-dimensional current measuring ability of an Acoustic Doppler Profiling Current meter, depth and bottom characterization of high precision acoustic pinging, and high data rate Iridium telemetry. All of these capabilities are in a compact, stable drifter that weighs less than 10 pounds and that has a very low profile at the sea surface. In addition, this early model of the Riverine Drifter has internal storage that allows many hours of data to be stored and retrieved at a later time to facilitate development of sampling and analysis strategies. Riverine Drifter generates and internally records a torrent of high quality data describing the aquatic environment it drifts through. A distillation of this information is sent to the user in Iridium data messages sent every ten minutes. Riverine Drifter has been tested in the field in three deployments in Boston Harbor.