Tanya Mendes Silveira

Psuty, N. P. and Silveira, T. M., 2011. Monitoring Shoreline Change along Assateague Barrier Island: The First Trend Report. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 800 – 804. Szczecin, Poland, ISSN 0749-0208 The application of rigorous protocols to conduct shoreline surveys in the Assateague Island National Seashore of the Northeast Coastal and Barrier Network of the National Park Service has generated a dataset that permits comparisons of shoreline positions at seasonal, annual, and long-term scales. The end product of the comparisons provides insights to the sediment supply, sediment budget, and sediment transport system operating along Assateague Island. Application of the Shoreline Change Mapper in conjunction with the USGS Digital Shoreline Analysis System portrays the geotemporal relationship of change through the 5-year period of data availability. Most of the island has undergone shoreline position change greater than the measure of uncertainty associated with the protocol (10 m), with some areas gaining as much as 462 m and others losing as much as 374 m during the 5-year period. Linear regression analysis depicts the 5-year trend for the entire island as a loss of 0.95 m/yr, whereas the losses within the NPS portion of the island were 1.48 m/yr. End-Point analyses of the data identify a loss of 2.40 m/yr for the entire island and 2.53 m/yr within the NPS portion.

Psuty, N. P. and Silveira, T. M., 2011. Tracking Coastal Geomorphological Change: an application of protocols to collect geotemporal data sets at the national level in the US. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 1253 – 1257. Szczecin, Poland, ISSN 0749-0208 The US National Park Service and the US Fish & Wildlife Service have joined forces in monitoring the geotemporal elements of their coastal land holdings. They have adopted a common protocol for tracking the position of the shoreline, 1-D, in and adjacent to their lands, as well as adopting a common method for collecting profiles, 2-D, and 3-D elevation models. In an unprecedented move, the two agencies are working together to build a coastal Geodatabase that will provide quantitative measures of seasonal, annual, and long-term changes in their coastal holdings. The data will be valuable in supporting decisions in their General Management Plans as well as the Comprehensive Conservation Plans. About 20 parks and refuges are involved in this first phase of coastal monitoring.

The CHIMERA project, contracted by the Portuguese Environment Agency (APA) and co-funded by the EuropeanUnion Cohesion Fund (Portugal 2020 | POSEUR) intended to characterize the sedimentary record of three 10km2 areas and one 5 km2 area in the Portuguese inner shelf. Multibeam bathymetry and backscatter, parametricecho-sounder, ultra-high resolution multichannel seismics and magnetic data were acquired along high resolutionorthogonal grids. The main aim of the project was to evaluate potential borrow areas for high-magnitude beachnourishments in long term eroding stretches of the Portuguese western coast. The diversity, the large density andthe high quality of geophysical data allow for a multidisciplinary geological interpretation of the datasets.In this presentation we focus on magnetic data and its interpretation combined with acoustic data. We applieda detailed processing scheme to acquired magnetic data, which allowed retrieving several components of themagnetic spectrum and estimating some source depths. We then analyzed the geological significance of theanomalies by studying their correspondence to seismostratigraphic units mapped from seismic data. Fit betweenmagnetic signature and geologic structure was found for most of the cases, although magnetic anomalies withinthe same wavenumber spectrum may express different geological units for each study area. A correspondence wastypically found for the basement, and for recent sedimentary structures such as paleo-channels and paleo-coastalbarriers. In other cases, low wavenumber anomalies may express intra-basement geology, too deep to be observedby our high-resolution seismics. For individual anomalies we check for a relation with shallow features, eventuallyarcheological artifacts.Publication supported by FCT- project UID/GEO/50019/2019 - Instituto Dom Luiz.

Silveira, T.M., Carapuço, A.M., Sousa, H., Taborda, R., Psuty, N.P., Andrade, C. and Freitas, C., 2013. Optimizing beach topographic field surveys: matching the effort with the objectives In any study design, the surveying approach should match the objectives, thereby limiting the effort to focus on the purpose of the inquiry. Often, in beach geomorphological research, study design is based on expert judgment, that does not assure the optimization of the field surveys. In this study, several dimensions of survey strategies were evaluated to compare the outcomes and uncertainties associated with field data collection. The objective of this work is to assess the accuracy of the derived volumes achieved by different survey strategies, including cross- and alongshore lines, with varying density and spatial distribution, to optimize the field survey effort. A number of survey strategies are simulated, covering a range of data resolutions and configurations, replicating a number of possibilities for fi...