COASTAL GEOLOGY AND PHYSICAL OCEANOGRAPHY - EXPLORING THE LINKS

For nearly as long as man has gone down to the sea, we have been aware that there is an inexorable link between the moving water and the changing coastal landscape. A primary focus of the nearshore processes community since the NSTS program in the late 1970's and through the series of major experiments at Duck, NC has been to quantitatively understand the evolution of surf zone morphology in the context of a rigorous knowledge of the wave and current processes operating during storms and on scales of less than roughly 1km, largely determined by the amount of beach that can be reasonably surveyed in a day. Much progress has been made as a result of these focused studies.

However the recent application of lidar technology to subaerial beach mapping has greatly extended our ability to quantify large scale beach changes as a result of major storms, outstripping the capabilities of most, if not all, physical oceanographic observation programs. This presentation will highlight some of the approaches being explored to study the interactions of coastal geology, physical oceanography and beach erosion with a focus on the application of the wave shoaling models. Two case studies will be presented, one detailing the use of a simple monochromatic wave refraction/diffraction model (REFDIF, written by Dr. James Kirby and colleagues, University of Delaware) in the vicinity of Wimble Shoals along the Outer Banks of NC (USA) (Cox, 1996 MS Thesis, Duke University), the second showing how a more complicated wave shoaling program (SWAN) has also been used to investigate wave height and direction changes in the vicinity of the Grays Harbor tidal delta on the SW Washington (USA) coast (Palmsten, 2001, MS Thesis, University of South Florida). In both cases the model predictions help us understand at least part of the reason behind regional scale coastline evolution in those areas.

As we move forward making our coastal science even more relevant to the temporal and spatial scales of societal interests (the length of a mortgage and the size of zoning districts are good places to start), we will of necessity be working closely with physical oceanographers to help us, as geologists, understand the forces responsible for shaping the landscape at ever increasing temporal and spatial scales.