Comparison of Present Day and Historical Dispersal Patterns in the Western Adriatic

Abstract

Award Number: N00014-04-1-0378 http://www.vims.edu/~ckharris LONG-TERM GOALSBy improving numerical representations of coastal circulation, sediment properties, and waves, we seek to develop reliable predictions of sediment concentration, transport and deposition. Calculations that simulate conditions during field experiments can be validated using observations. We can then extrapolate to longer timescales by running longer simulations, and by predicting dispersal patterns under configurations that represent past geologic or climatic conditions, when sediment and freshwater inputs would have been different. By using a well-tested model to evaluate the impact that such shifts in sediment and freshwater delivery have had on seafloor texture, we hope to bridge the gap between present day observations and the events and climatic shifts capable of leaving stratigraphic signals. OBJECTIVESSediment delivery, flux, and deposition are quantified within a three-dimensional hydrodynamic model that links sediment transport in the western Adriatic Sea to deposition. The study focuses on evaluating sediment dispersal in the Adriatic under different wind regimes: the Bora winds are storm winds that blow from the northeast, and the Sirocco winds tend to be less energetic, but are directed up the axis of the Adriatic from the southeast. The largest point source of sediment within the Adriatic is the Po River, but dispersal in that region is poorly resolved in our current model (2-3 km resolution). This has motivated focus on the Po delta to use the model to evaluate competing hypothesis for sediment dispersal and delta progradation there. APPROACHTwo systems have been considered. First, we study the modern Adriatic and continue to build a realistic simulation of the 2002 / 2003 study period. Our colleagues have a rich data set to classify both seafloor properties and water column sediment transport during this time, from the PASTA (Po and Apennine Sediment Transport and Accumulation) experiment. Secondly, a related study, reported last year, sought to quantify dispersal patterns of paleo-Po River sediment under conditions representative of the last glacial maximum (LGM), 18,000 years before present, when sea levels were 120 m lower.