BED FORM DEVELOPMENT AND DISTRIBUTION PATTERN, 

 PARKER AND ESSEX ESTUARIES, MASSACHUSETTS 



by 



Jon C. Boothroyd 



and 

 Dennis K. Hubbard 



I. INTRODUCTION 



Bed forms, primary sedimentary structures and geometry of sand bodies in estuaries have 

 been studied by the Coastal Research Center, University of Massachusetts, since 1965. 

 (Coastal Research Group, 1969), (DaBoU, 1969), (Hartwell, 1970), (FarreU, 1970). 

 Complete tidal-cycle velocity and depth data have been collected at over 300 hydrographic 

 stations in 15 New England and Long Island estuaries by the Center. Extensive mapping of 

 intertidal sand bodies with concurrent recording of type and orientation of bed forms was 

 also carried out. Studies of the Parker River-Essex estuary area are discussed by Hayes, 

 Anan, and Bozeman, (1969), and by the Coastal Research Group, (1969). This study 

 continues their work and documents the development and migration of estuarine bed forms 

 in response to complex flow patterns and to differences in intertidal and subtidal 

 topography. 



The study area is located in the southern part of the Merrimack embayment on the 

 northeastern Massachusetts coast. (Figure 1.) Figure 2 is an aerial oblique view, taken at low 

 tide, looking southeast over the study area. Mean tidal range in the area is 2.6 meters, or 

 mesotidal in the classification system of Davies (1964). 



Discussion in this report is limited to the lower Parker River intertidal sand bodies and 

 subtidal channels and the flood-tidal delta of the Essex estuary. Description of various 

 topographic forms of flood-tidal deltas and adjacent channels follows the classification of 

 the Coastal Research Group (1969). Figures 3 and 4 illustrate these forms as applied to the 

 Parker and Essex estuaries. 



n. FIELD METHODS 

 1. Diving Barge 



In an attempt to improve correlation of tidal-current velocity and depth parameters with 

 bed form type, orientation, and migration habit, a program was developed that allowed 

 divers to make bottom observations while velocity and depth measurements were being 

 recorded. A stable diving platform (barge) was designed for work in current velocities up to 

 150 centimeters per second and water depths to 7 meters. 



The barge used as a stable diving platform is a 10-by 16-foot open platform with a 2-by 

 4-foot center hatchway. (Figure 5.) Flotation is by Styrofoam billets; the barge draws 4 

 inches of water. A tetrapod frame straddles the hatchway and it in turn supports an 

 8-foot-long boom. A 3-by 5-foot, weighted, slatted staging assembly is suspended 3 feet 

 below deck level under the hatchway. 



Diver movement to and from the water is through the center hatchway. The staging 

 serves as an underwater access point to the barge. A diver can remain on the staging in up to 



