INTEGRATED OCEANOGRAPHIC AND SEABED TIME-SERIES ANALYSIS TO EXAMINE MODERN SEABED-WATER COLUMN COUPLING

Modern coastal sedimentary processes are driven by the interaction between the local oceanography and the availability of sources and sinks of sediments. Geological investigation of such processes has traditionally relied upon the examination of the resultant distribution of sediment and sediment facies. It is assumed that the modern sediment distribution is a reasonable residual indicator of the scale and variability of modern oceanographic processes.

As coastal oceanographic instrumentation has improved we now have the ability to directly monitor the scale and variability of these processes at scales similar to those achievable using seabed mapping system such as multibeam sonar or sidescan. By coupling fine-scale oceanographic observations with time series of seabed geomorphic and sedimentologic measurements we can propose and test models of coastal evolution over scales more immediately useful for change prediction.

Examples of the coupling of coastal tidal and estuarine circulation are presented showing the modern fine –scale circulation and the directly resulting seabed relief and sediment distribution. The oceanography is examined through the use of ADCP cross-sections, water column acoustic scattering and undulating oceanographic profilers. The prime tool used for examining the seabed is bathymetry and backscatter derived from multibeam sonar systems. Monitoring seabed change requires significant investment in calibration methods to ensure repeatability. Imperfections in sonar system calibration limit the unambiguous interpretation of the results.