Soft-rock coastal cliff retreat progresses by an intermittent and discontinuous series of slope mass movements, generally accepted to be concentrated during phases of strong wave attack or heavy rain. One of the fundamental limitations to improving understanding of these processes is a lack of accurate quantitative data on the hydrological and geotechnical behaviour of the cliff slope. In this study, high-resolution terrestrial surveys of coastal change over a fifteen year period have been analysed and combined with hydrological and geotechnical simulations of cliff behaviour under rainfall stress. The input parameters for the simulations have been established from site survey, cross-checked with data from a range of published literature. The numerical model has been applied to typical hydrological, climatic and geotechnical conditions at Covehithe, Suffolk. In addition, analyses of water levels and beach elevations have subsequently been included using archive observation data, to further investigate the mechanisms governing the nature of change at the study site. Key findings include: (a.) high-resolution modelling of rainfall-infiltration processes combined with slope stability analysis provides a unique insight into the complex interaction between slope morphology and dynamic hydrology in soft sea cliffs. (b.) detailed analysis of daily factors of safety related to specific daily rainfalls is significant in reproducing failure conditions at the study site, and elucidates the complex interaction between cliff stratigraphy, cliff hydrology and rainfall. (c.) The results of the water level and beach elevation analyses show that marine processes are significant to the generation of cliff instability, consistent with the field observations and with the Sunamura (1983) model. These findings suggest that the instability of soft sea-cliffs results from complex and interacting controls that require an approach utilising a fully integrated transient hydrology and slope stability modelling. These results have significant implications for current coastal management practice.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:629701 |
| Date | January 2014 |
| Creators | Chapman, Neil |
| Publisher | Birkbeck (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://bbktheses.da.ulcc.ac.uk/98/ |
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