Dr. Thomas Ballestero Dr. David Watt Dredging to maintain the requisite depth for commercial traffic has been necessary in the Lower Piscataqua River in order for Portsmouth to remain a viable seaport. The Army Corps of Engineers has been engaged in projects to deepen and widen the main channel and turning basins in critical areas. Shoals developing across the channel must be repeatedly dredged every 6-8 years. Oil terminals and other facilities along the NH side of the river routinely have to remove bottom material to allow vessel docking. These dredging operations are critical to the safety of harbor traffic transporting hazardous cargoes as well as the commercial success of several important industries using Piscataqua River terminals.
Environmental issues arise with each new dredging project.
The release of sediment chemicals during removal and disposal is also of concern. In response, a sediment transport research program has been initiated to obtain basic information essential for the informed development of a channel maintenance policy. The study will focus on determining where the coarse-grained bottom material responsible for shoaling originates, what the transport rates are and where deposition takes place. Measurements include bottom sediment sampling, benthic boundary layer current velocities, bedload transport rates and acoustic determination of bathymetry. Data will be used with mathematical models of sediment processes.