Goud Margaret R.

No Thumbnail Available
Last Name
Goud
First Name
Margaret R.
ORCID

Filters

3 2
1983 - 1987 3
2 1
3
Reset filters

Settings

Search Results

Now showing 1 - 3 of 3
  • Thesis
    Prediction of continental shelf sediment transport using a theoretical model of the wave-current boundary layer
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1987-09) Goud, Margaret R.
    This thesis presents an application of the Grant-Madsen-Glenn bottom boundary layer model (Grant and Madsen, 1979; Glenn and Grant, 1987) to predictions of sediment transport on the continental shelf. The analysis is a two-stage process. Via numerical experiment, we explore the sensitivity of sediment transport to variations in model parameters and assumptions. A notable result is the enhancement of suspended sediment stratification due to wave boundary layer effects. When sediment stratification is neglected under conditions of large wave bottom velocities, concentration predictions can be more than an order of magnitude higher than any observed during storm conditions on the continental shelf. A number of limitations to application emerged from the analysis. Solutions to the stratified model are not uniquely determined under a number of cases of interest, potentially leading to gross inaccuracies in the prediction of sediment load and transport. Load and sediment transport in the outer Ekman Layer, beyond the region of emphasis for the model, can be as large or larger than the near-bottom estimates in some cases; such results suggest directions for improvements in the theoretical model. In the second step of the analysis, we test the ability of the model to make predictions of net sediment transport that are consistent with observed sediment depositional patterns. Data from the Mid-Atlantic Bight and the Northern California coast are used to define reasonable model input to represent conditions on two different types of shelves. In these examples, the results show how the intensification of wave bottom velocities with decreasing depth can introduce net transport over a region. The patterns of erosion/deposition are shown to be strongly influenced by sediment stratification and moveable bed roughness. Also predicted by the applications is a rapid winnowing out of fine grain size components when there is even a small variation of bed grain size texture in the along-flow direction.
  • Technical Report
    Survey of shoreline structures, Popponesset Beach, MA
    (Woods Hole Oceanographic Institution, 1983-05) Goud, Margaret R. ; Aubrey, David G.
    The structures along a 12 km section of the shoreline of Cape Cod, Mass., were evaluated for condition and effectiveness at protecting the coast. Structures in the area include groins, jetties, revetments, and seawalls; each has been located, photographed and described. The region has been subject to erosion in recent years, including the loss of a 1 km section of barrier spit. The role of shoreline structures in controlling or enhancing the erosion was examined as part of a larger study of coastal processes in the area. The shoreline structures serve two primary functions: beach enhancement and protection of the bluffs from erosion. The structures• effects on bluffs and beaches in their immediate vicinity (approximately lOOm along the coastline to the north and south of the structure) are detailed in this report. Seawalls generally protect the cliffs into which they are built without enhancing erosion of surrounding bluffs, though the bluffs are protected at the expense of the beaches in the central area (Meadow Point). Large scale changes in beach configuration are not primarily caused by local, small-scale structures, but rather by a more regional paucity of sand input into the system. This scarcity is caused in part by large jetties controlling inlet flows to Waquoit Bay, which impedes free transport of sand into the area.
  • Technical Report
    Coastal sediment transport, Popponesset Beach, MA
    (Woods Hole Oceanographic Institution, 1983-08) Aubrey, David G. ; Goud, Margaret R.
    Pathways and rates of near-bed sediment transport near Popponesset Beach, MA ., were calculated using several distinct techniques. For the nearshore platform, sand transport in the form of sand waves was determined from vertical aerial photography spanning periods of four decades. In addition, calculations based on theoretical and empirical equations for near-bed sediment transport were made using field measurements of wind waves and tidal currents. Net sediment transport to the southwest inferred from these two techniques differed by about a factor of five. The higher net transport rate predicted in the aerial photographic method is a result of lack of wave measurements during storm conditions. Storm waves increase the net transport through a local increase in bed shear stress. Net transport to the southwest across the platform is between 700 and 3300 m3/yr. Littoral sand transport along Popponesset Beach was calculated from one month of directional wave measurements, extrapolated to a yearly value using long-term meteorological observations. Littoral transport from these calculations is 10,000 m3/yr to the northeast, opposite the sense of alongshore transport in the shallow nearshore. Patterns of shoreline change are discussed from a historical perspective, and using the transport calculations discussed above. Several management alternatives for coping with predicted shoreline change are presented for consideration by the Town of Mashpee.