This paper discusses the application of various marine geophysical techniques to engineering studies in coastal and estuarine environments. Sea bed morphology can be examined using echo sounding and sidescan sonar whilst geological structure is investigated using continuous seismic profiling surveys based on sparker and boomer sources. In both cases samples of sea floor sediments and rocks are collected and boreholes drilled to calibrate the seismostratigraphy in terms of geological structure. Current geophysical equipment and methods are reviewed and are illustrated by three case histories. The first describes a geophysical survey undertaken in the Wash to provide information on sediment movement as part of a feasibility study for bunded reservoir construction. The second discusses an appraisal of the engineering characteristics of the near-shore environment carried out in connection with coastal engineering studies in Lyme Bay, Dorset. Finally, a description is given of a survey which formed part of a study to investigate the distribution of sand and gravel aggregate resources off the East Anglian coast.
Whilst there have been continuous improvements in seismic profiling equipment and survey techniques, most of the underlying principles and interpretation techniques have remained the same. By combining the results from marine seismic surveys and geological sampling programmes it is possible to achieve an accurate assessment of the sub-bottom geology in the near-shore environment.