Prediction of continental shelf sediment transport using a theoretical model of the wave-current boundary layer

Abstract

Abstract : 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 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 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 improvement 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.