Reports
Upper Bay current velocity and bottom sediment characterization in proposed open-water sites
1996, Halka, J.P., Panageotou, W., and Ortt, R.A., Jr.
File Reports, Coastal and Estuarine Geology, File Report 1996-05
Project Description
Additional open-water sites in the upper Chesapeake Bay are being considered for the placement of dredged sediments as part of the Governor's Comprehensive Dredged Sediment Management Plan. Two sites under active consideration are tentatively named Area G-East and Site 92. Area G-East was identified as a potential location for the placement of dredged sediment in the fall of 1995. Subsequently, meetings between Port of Baltimore interests and resource management agencies identified Site 92 as another location with potential for sediment placement. The bathymetry in the vicinity of Pooles Island, the existing designated sites, and these additional proposed sites is shown in Figure 1. The boundaries of both Area G-East and Site 92 are dashed in this figure because the sites suitability for sediment placement is undergoing environmental analysis and the boundaries are subject to alteration. In order to assist in determining the suitability of the proposed sites for the placement of dredged sediment and provide information necessary for the preparation of an Environmental Assessment, the Maryland Geological Survey (MGS) collected and analyzed data to characterize the physical and sedimentary environment in the vicinity of these proposed sites.
This effort included three major tasks:
- Collection of high-resolution bathymetric data and characterization of the bottom topography from these data,
- Determination of bottom sediment characteristics in the vicinity of the proposed sites, and
- Collection of water column current velocity data and calculation of bottom shear stress.
Sites proposed for the acceptance of dredged sediments should have bottom sediment characteristics similar to those of the sediments proposed for placement and the bottom configuration should be such that the sediment will tend to remain in place rather than impacting other areas of the upper Bay that may have high resource value. The combination of detailed bathymetry and bottom sediment characterization provides information suitable for this analysis and contributes to a determination of the potential site capacity, impacts to adjacent areas, and placement methodology. The tidal current velocity data can be used to calculate the potential bottom shear stress exerted by regular tidal exchange and determine the potential for dredged sediments to experience erosion in excess of that observed and/or calculated to occur at the open-water placement sites previously utilized in the vicinity.
