Fine-scale sediment distribution at the mouth of the Merrimack River


The seafloor at the mouth of the Merrimack River, Massachusetts, is a complex mosaic of fluvial and coastal sediments that are reworked by currents and the seasonally variable wave conditions in the western Gulf of Maine. This study integrates a series of new closely-spaced sediment samples and acoustic data with existing geophysical data (airborne lidar bathymetry, multibeam echosounder (MBES), swath interferometry, and sidescan- sonar backscatter) to characterize the local seafloor geology, sediment distribution and surficial processes at the mouth of the Merrimack River. Sediment-sample and seafloor-video data were collected in 2009-2010 at more than 150 sites and an additional MBES survey was completed in August 2010. Here we present the preliminary results from the analyses of these datasets with a focus on the spatial distribution of the sediments discharged from the Merrimack River and their assimilation into the coastal environment of the Gulf of Maine. This study builds on existing research from a US Geological Survey regional mapping program (OFR2007-1373 - http://pubs.usgs.gov/of/2007/1373/). Using GIS and remote-sensing software, we relate the grain- size results from the new seafloor samples along with the MBES data to the existing backscatter imagery and bathymetry data. The integration of these datasets in the GIS allows us to identify fine-scale patterns of sediment distribution and surficial seafloor features that illustrate the effects that regional tides, currents and strong winter storms have on these fluvial and coastal sediments.


Center for Coastal and Ocean Mapping

Publication Date


Journal or Conference Title

Coastal Geotools 2011



Conference Date

21-24 March, 2011

Publisher Place

Myrtle Beach, SC, USA


U.S. Geological Survey

Document Type

Conference Proceeding