Marsh surface sediment deposition and the role of tidal creeks: Implications for created and managed coastal marshes |
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Authors: | Denise J. Reed Thomas Spencer Anne L. Murray Jonathan R. French Lynn Leonard |
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Affiliation: | (1) Department of Geology and Geophysics, University of New Orleans, 70148 New Orleans, LA, USA;(2) Cambridge Coastal Research Unit, Department of Geography, Cambridge University, CB2 3EN Cambridge, UK;(3) Department of Earth Sciences, University of Leeds, LS2 9JT Leeds, UK;(4) Coastal and Estuarine Research Unit, University College London, WC1N 1PG London, UK;(5) Department of Earth Sciences and Center for Marine Science Research, University of North Carolina, 601 S. College Rd., 28403 Wilmington, NC, USA |
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Abstract: | The need to understand the processes contributing to marsh sedimentation has become more urgent with the recent recognition of the role of tidal marshes as sea defences, as well as the many restoration efforts currently under way. This study was designed to build upon previous sedimentation work at Scolt Head Island by Combining techniques for measuring short-term sedimentation, with detailed assessment of hydroperiod, previously used only in comparison with longer-term accretion measurements or in micro-tidal systems. Measurements of water level, sediment deposition (at various distances from the creek margin) and suspended sediment concentration (SSC) (creek margin and an interior site) were made at Hut Marsh over three sequential over-marsh tides during May 1994. Sediment trap data show a significant trend of declining sediment deposition away from the creek when data from all three tides are combined. All tides show higher SSC on the flood tide than on the ebb tide at the creek margin location. There is little difference in flood and ebb SSCs at the interior site. An order of magnitude decrease in sediment deposition within 20 m on the creek shows the rapidity with which sediment is deposited on these marshes. Higher tides influence both the magnitude and pattern of marsh surface sediment deposition. Increased creek velocities on higher tides provide more potential for resuspension within the creek and increase the supply of sediment to the marsh surface. This study suggests that the design of tidal creeks may be essential for the development of sustainable coastal marshes in restoration projects. |
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Keywords: | Creek Restoration Salt marsh Scolt Head Island Sedimentation Suspended sediment concentration |
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