Spatial variability of bottom types in the lower Chesapeake Bay and adjoining estuaries and inner shelf |
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Authors: | L D Wright D B Prior C H Hobbs R J Byrne J D Boon L C Schaffner M O Green |
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Institution: | 1. Virginia Institute of Marine Science, School of Marine Science, College of William and Mary, Gloucester Point, VA, 23062, U.S.A.;2. Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, 70803, U.S.A.;1. I-Geo Disaster Research Center, Faculty of Engineering & Technology Infrastructure (FETI), Infrastructure University Kuala Lumpur (IUKL), 43000 Kajang, Selangor, Malaysia;2. Water Resources Engineering & Management Research Center (WAREM), Universiti Teknologi MARA, 13500 Permatang Pauh, Pulau Pinang, Malaysia;3. Faculty of Computer & Mathematical Sciences, Universiti Teknologi MARA, 13500 Permatang Pauh, Pulau Pinang, Malaysia;4. Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, United States |
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Abstract: | The spatial distributions of the bed textural and morphologic properties that influence boundary-layer roughness characteristics in the lower Chesapeake Bay, the lower portions of the York, James and Elizabeth Rivers, and the adjacent inner continental shelf were systematically mapped. A high resolution, fully-corrected side-scan sonar mapping system (100 kHz) was used for remote acoustic detection of bottom roughness, supported by ‘ground-truthing’ by direct in situ observations by divers. These complementary methods proved to be especially effective in detecting a wide range of roughness-controlling bed surface properties at various scales. Fine-scale variations in sediment size and associated bottom texture are considered to be the main source of heterogeneity in Nikuradse (skin friction) roughness. A wide variety of small- and intermediate-scale morphologic elements provide meso-scale and small-scale distributed (form drag) roughness. Depending upon location, the distributed roughness may be either biogenic or hydrodynamically induced (by currents and waves), although anthropogenic roughness prevails in certain instances (e.g. port areas). In terms of particular combinations of roughness scales and types, combined sonar and diver observation data allow the beds to be systematically but qualitatively classified into 10 bottom types, each of which is associated with a particular type of subenvironment. |
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Keywords: | benthic environment boundary layers estuaries continental shelf Chesapeake Bay side-scan sonar bottom topography |
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