Saltmarsh Circulation, Inundation and Bathymetric Mapping using HF-radar

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An understanding of the circulation patterns in the extensive salt marsh ecosystems throughout the world is important for a variety of reasons, including the assessment of sediment and pollutant transport within the marshes, and the residence or flushing times of specific regions with respect to commercially important organisms or pollutants. Modeling studies suggest circulation pathways can be quite complex, depending critically on marsh creek bathymetry and curvature, and on connectivity at differing topographic levels within the cyclically inundated marsh intertidal. Effective measurement of circulation of these systems is difficult, owing to the circuitous interconnected tidal creeks, the variety of scales that must be addressed, and the variability of pathways the water may traverse as the topographically complex intertidal areas are successively flooded and drained through each tidal cycle. The PI proposes to add a pair of VHF-radar systems to an upcoming DOE-funded intensive field study directed by colleagues at Skidaway, to demonstrate the radars utility to measure vector velocity within both the channels and inundated intertidal subregions of the marsh, to monitor the presence or absence of water within the intertidal marsh areas, and to invert spectral returns to assess bathymetry in the illuminated area, all at high horizontal resolution. The DOE-sponsored study will provide an extensive data-base against which to test the feasibility of using the VHF-radar system in the salt marsh.Goals: The funding requested will test the ability of paired VHF radars to:1) measure vector velocities within the tidal channels and intertidal marsh,2) detect the transition between inundated and uninundated intertidal areas, and depth limits of detection,3) estimate depths of shallow inundated areas.Broader ImpactsThe ability to measure circulation at high horizontal resolution will provide an order one improvement in our understanding of these issues. Such measurements, along with the ability to define saltmarsh bathymetry and topography at high resolution, will vastly improve our ability to model such systems accurately as well. Such models would provide a significantly improved tool for the use of society?s agencies who are charged with protection and permitting in the marsh setting. Educationally, the database developed with this project will provide engaging student projects over the next several years. Finally, the project will provide a database for our new faculty hire at SkIO who will be joining SkIO as an Assistant Professor in July 2010. She will be able to use the data to develop her modeling program as applied to the rich local salt-marsh setting.