Sediment Transport in the Coastal Environment
Prepared under the support of Dames and Moore, Consultants in the Environmental and Applied Earth Sciences, Cranford, New Jersey, through funds provided by New Jersey Public Service Electric and Gas Company, Newark, New Jersey.
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Cambridge, Mass. : Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics, Dept. of Civil Engineering, Massachusetts Institute of Technology
2022
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| Online Access: | https://hdl.handle.net/1721.1/142976 |
| _version_ | 1811096537825017856 |
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| author | Madsen, Ole Secher Grant, William D. |
| author_facet | Madsen, Ole Secher Grant, William D. |
| author_sort | Madsen, Ole Secher |
| collection | MIT |
| description | Prepared under the support of Dames and Moore, Consultants in the Environmental and Applied Earth Sciences, Cranford, New Jersey, through funds provided by New Jersey Public Service Electric and Gas Company, Newark, New Jersey. |
| first_indexed | 2024-09-23T16:45:16Z |
| id | mit-1721.1/142976 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:45:16Z |
| publishDate | 2022 |
| publisher | Cambridge, Mass. : Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics, Dept. of Civil Engineering, Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1429762022-06-14T03:01:45Z Sediment Transport in the Coastal Environment Madsen, Ole Secher Grant, William D. Prepared under the support of Dames and Moore, Consultants in the Environmental and Applied Earth Sciences, Cranford, New Jersey, through funds provided by New Jersey Public Service Electric and Gas Company, Newark, New Jersey. The subject of sediment transport in the coastal zone is investigated and the answers to some of the basic questions of sediment transport in unsteady, oscillatory flow are presented. By adopting Jonsson's (1966) results for the bottom shear stress associated with a simple wave motion, it is shown that Shield's criterion for the initiation of sediment movement on a flat bed holds in unsteady as well as steady flow. A simplified analysis as well as experimental data show the side effects associated with the experimental procedure in which a tray containing sediment is oscillated in still water is generally insignificant and is, therefore, a valid procedure for studying certain aspects of wave sediment interaction. Also, Shields Parameter is identified as the physically important parameter quantifying the fluid sediment interaction. An empirical relationship between a non-dimensional average sediment transport rate and Shields Parameter is found by reanalyzing the experimental data on the rate of sediment transport in oscillatory flow obtained by Einstein and co-workers at Berkeley. This relationship is similar to the Einstein-Brown sediment transport relationship in unidirectional, steady flow. By generalizing Jonsson's expression for the bottom shear stress associated with a sinusoidal wave motion, it is shown that the empirical sediment transport relationship may be derived from a quasi steady application of the Einstein-Brown sediment transport relationship. Also, it is demonstrated that the empirical relationship obtained using a friction factor based on grain roughness is capable of predicting sediment transport rates observed in experiments where bed forms were present. The general application of the derived sediment transport relationship for predicting net rates of sediment transport in the presence of second order effects such as bottom slope, wave asymmetry, mass transport currents and coastal currents is discussed. This discussion serves also to identify needed areas for future research. It is concluded that only the case of a small amplitude wave and a steady current seems to be understood to the extent that it is reasonable to evaluate the resulting sediment transport with any degree of confidence. Fortunately, this is a rather important situation in most offshore regions. A general numerical model is developed for the sediment transport and topographical changes resulting from spatially varying wave and current conditions. A simple numerical example of the evaluation of the topographical changes in the vicinity of the tip of a long straight breakwater is presented for periodic waves normally incident on the breakwater and a current parallel to the breakwater. This numerical example is chosen to resemble rather severe conditions for the Atlantic Generating Station (AGS) site with a maximum orbital wave velocity of 3.2 ft/sec (1 m/sec) and a current velocity 0.5 ft/sec (.15 m/sec). The results are.presented in a topographical relief map showing areas of scour and accretion of the order 0.78 inches/day (2 cm/day) at a maximum. Although the results of the example are somewhat more qualitative than-quantitative, it is felt that they provide a representative picture of the expected bottom changes in the vicinity of the AGS. 2022-06-13T13:06:51Z 2022-06-13T13:06:51Z 1976-01 209 https://hdl.handle.net/1721.1/142976 2234779 23473 R (Massachusetts Institute of Technology. Department of Civil Engineering) ; 76-7. Report (Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics) ; 209. application/pdf Cambridge, Mass. : Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics, Dept. of Civil Engineering, Massachusetts Institute of Technology |
| spellingShingle | Madsen, Ole Secher Grant, William D. Sediment Transport in the Coastal Environment |
| title | Sediment Transport in the Coastal Environment |
| title_full | Sediment Transport in the Coastal Environment |
| title_fullStr | Sediment Transport in the Coastal Environment |
| title_full_unstemmed | Sediment Transport in the Coastal Environment |
| title_short | Sediment Transport in the Coastal Environment |
| title_sort | sediment transport in the coastal environment |
| url | https://hdl.handle.net/1721.1/142976 |
| work_keys_str_mv | AT madsenolesecher sedimenttransportinthecoastalenvironment AT grantwilliamd sedimenttransportinthecoastalenvironment |