My research program is designed to increase our understanding of the dynamics governing the transport of fine-grained sediments in coastal and estuarine waters. In broad outline, this program consists of three principal components: field and laboratory experimental studies, instrument design and development, and numerical computer modeling. The field and laboratory investigations seek primarily to document the response of the sediment-water interface to both long-term persistent and short-term aperiodic, storm related factors. Many of the instrument systems required to obtain these observations have been designed and constructed at the University of Connecticut. Data provided by the deployment of these arrays in a variety of coastal environments has shown the interfacial response to be highly non-linear and significantly variable in both space and time. Such variability complicates specification of transport algorithms in numerical predictive models. Ongoing work seeks to extend and refine these observations to permit resolution of the specific factors governing transport non-linearities including consideration of biologically mediated variations in sediment fabric, particulate associated alterations in boundary shear stress, and advective effects associated with variations in the local flow field.

The experimental work will require continuing redesign and modification of the available instrument arrays. Existing optical systems, presently used to monitor suspended material concentrations, are to be improved and supplemented by a variety of acoustic systems in order to increase both spatial and temporal resolution. In addition, the field arrays are to be supplemented by a series of sensors intended to detail the fabric of the sediment column in the immediate vicinity of the sediment-water interface. A number of systems are to be tested including radioactive probes, acoustic and electromagnetic systems and simple mechanical probes with ultimate selection based on simplicity of operation and reliability and the potential to yield vertical resolution over scales of 1 mm or less.

Patterns of recruitment, abundance and dominance within several subtidal communities in southern New England have been found to persist year after year over large areas of the bottom. This long-term persistence is not expected in such an open system with disturbances continually creating open patches for recruiting larvae whose identity and abundances change both temporally and spatially. Present research suggests that the persistence results from strong local control of recruitment that overrides any variability in larval production and dispersal of species from outside a site. We have been testing this hypothesis by conducting manipulative field experiments which delineate abiotic and biotic controls of local recruitment and how these affect community establishment and development.

The variety of experimental work is being complemented by concurrent continuing development of a series of numerical models intended to incorporate the laboratory and field data for calibration purposes and to permit the extension of these data in space and time for predictive purposes.

Fredette, T.J., W.F. Bohlen and D.C. Rhoads. 1988. Erosion and resuspension effects of Hurricane Gloria at Long Island Sound dredged material disposal sites. Proc. Of Water Quality 1988. U.S. Army Corps of Engineers, Hydraulic Engineering Center, Davis, CA.

Fenster, M.S., D.M. Fitzgerald, W.F. Bohlen, R.S. Lewis and C.T. Baldwin. 1990. Stability of giant sand waves in eastern Long Island Sound. U.S.A. Marine Geol. 91: 207-225.

Bohlen, W.F. 1990. Ocean disposal of particulate wastes: practices, properties and processes. In: K.R. Demars and R.C. Cheney (eds.). Geotechnical Aspects Of Ocean Waste Disposal. Amer. Soc. for Testing and Materials, Spec. Pub.

Bohlen, W.F., D.R. Cohen and M.M. Howard-Strobel. 1992. An Investigation of Sedimentation Induced by Gas Pipeline Laying Operations in the Vicinity of the Oyster Bed Lease Areas, Milford, CT. Prepared for Iroquois Gas Transmission System. Shelton, CT. 40 pp. & Figs.

Bohlen, W.F., D.R. Cohen and M.M. Howard-Strobel. 1992. An Investigation of Water Column Currents and Suspended Sediment Dispersion Associated with Dredged Material Disposal Operations, Cornfield Shoals Disposal Site, Eastern Long Island Sound. Prepared for Science Applications international Corporation. Newport, RI. 49 pp. & Figs.

Lissner, A., C. Phillips, E. Waddell, P. Hamilton, A. Barnett, D. Diener, P. Raimondi and W.F. Bohlen. 1995. Monitoring Assessment of Long-term Changes in Biological Communities in the Santa Maria Basin: Phase III. Report submitted to US Department of Interior Minerals Management Service/National Biological Service. Cont. No. 14-35-0001-30584.

Bohlen, W.F., M.M. Howard-Strobel, D.R. Cohen and E.T. Morton. 1996. An Investigation of the Dispersion of the Sediments Resuspended by Dredging Operations in New Haven Harbor. Submitted to New England Division, US Army Corps of Engineers. Waltham, MA.