Inverse Methods in Coastal Morphology

Abstract

Long-term regional sediment accretion and erosion patterns have been examined from a series of historical bathymetric surveys covering a period of almost 150 years. The surveys cover an area approximately 30km by 100km and include a region of highly mobile sandbanks which lie a few kilometres offshore from the port of Gt. Yarmouth in the United Kingdom. The survey data has been used to invert a simplified morphological governing equation. The inverse problem has been solved for each consecutive pair of surveys in order to construct a series of results which represent the pattern of net accretion and erosion associated with the observed morphological evolution. These results provide some insight to the long-term morphological evolution of the sandbanks, and suggest that the combined effect of non-diffusive processes varies more rapidly than the morphology of the sandbanks themselves. Introduction The numerical prediction of seabed evolution over periods of time useful for strategic management is still in its infancy. This has been due both to a scarcity of appropriate data and gaps in our understanding of the dominant physical processes governing long-term coastal evolution. This paper describes recently developed inverse methods which may provide a means of improving our understanding of the patterns of long-term sediment movement and give the prospect of predicting their variation over time. t School of Civil Engineering, University of Nottingham, Nottingham, NG7 2RD, UK 2 Dept of Applied Mathematics and Theoretical Physics, University of Cambridge, CB3 9EW, UK