SPATIO-TEMPORAL VARIABILITY IN THREE-DIMENSIONAL COASTALMORPHOLOGY: BOGUE BANKS, NORTH CAROLINA

摘要

Accurate and repetitive documentation of beach and nearshore morphologyrnremains an essential link in addressing numerous coastal research and managementrnconcerns. However, many compartments along the North Carolina coast suffer from arnlack of quantitative data to accurately assess these concerns. Morphological change isrnspatially and temporally complex due to the various physical, geological, andrnanthropogenic factors that influence littoral processes. Although beachface and nearshorernmorphology and the analysis of change are four-dimensional phenomena (X,Y,Z andrntime), they have typically been inferred from one-dimensional data or grossly interpolatedrnbetween two-dimensional cross-sections where no data exists. Advances in coastalrnsurveying and geographic information systems technology now permit the acquisition andrnprocessing of three-dimensional topographic data that can be seamlessly merged in thernsurfzone with high-resolution bathymetry. Acquisition methods employed for the BoguernBanks monitoring project take advantage of geodetic global positioning systemsrntechnology coupled with real-time kinematic baseline processing and motioncompensated,rnshallow-water sonar. Operating in a continuous collection mode allows forrnexceptionally dense coverage of data not only in the shore perpendicular direction, butrnalso in the alongshore direction for the creation of 3D, grid-based maps for multi-userrnanalyses in a GIS environment. Preliminary results from the first two quarterly surveysrnshow considerable spatial variation in the datum-derived shoreline between May 2002rnand August 2002. Specific areas of shoreline, volume and slope variability are associatedrnwith a recent renourishment project that is attempting to gain equilibrium.