Project Description
Our ability to quantify sediment transport rates in nearshore Texas waters is extremely limited, in part due to a scarcity of high-quality field data needed to calculate sediment transport quantities in a comprehensive manner. Understanding nearshore sediment transport pathways is critical in properly quantifying regional coastal sediment transport. This is important for successful implementation of any new coastal flood and erosion risk mitigation feature such as coastal structure, beach nourishment or nearshore beneficial use dredge material (BUDM) placement projects. Numerical modeling studies carried out to date suggest that alongshore sediment transport pathways are more complex than simple littoral drift computations based purely on directional wave forcing suggest. The few available modeling results and limited field data suggest that multiple modes of alongshore transport exist, sometimes acting simultaneously in opposing directions at different points of the cross-shore beach profile. Figures and additional explanations provided as supplemental material help explain this situation more clearly. The different modes of transport may be attributed to two different forcing mechanisms, the first, a relatively narrow band of wave driven littoral drift along the coastline, and the second a much broader band of current driven transport extending into deeper water. In addition, to this apparent variability in transport magnitude and direction along a profile, seasonality of hydrodynamic forcing and corresponding sediment transport creates a complex system that is only poorly understood but critical to any coastal Texas project. Recognizing the need for additional information from field measurements, this data collection and research project gathered new field data to further understanding of nearshore wave and current conditions in Region 1 of the Texas Coast (upper Texas coast including Galveston Island) with a focus on identifying the presence of nearshore currents that reverse the dominant longshore direction in some monthly or seasonal periods, evaluating their potential to impact nearshore sediment transport pathways, and estimating alongshore sediment transport quantities. The hypothesis for this project is that the influence of offshore currents in the Gulf of Mexico extends sufficiently close to shore that offshore currents can have an impact on nearshore currents and the resulting sediment transport pathways near the coast.
Basics
Classification
- Study/Research Project