(15) Autogenic submarine terrace formed by wave erosion during early stage of sea-level rise: implication from numerical experiments
Center for Water Environment Studies, Ibaraki University
A numerical experiment was performed to investigate the relationship between submarine topography formed by wave erosion and relative sea-level change. The experiments simulated the development of submarine topography under the postglacial sea-level rise during the last 20,000 years by means of the sea-level model of Sunamura (1978). The mathematical model used in this study is based on hypothesis that the erosion rate depends on the assailing force of waves at the cliff base in relation to the resisting force of rocks, as with the previous studies (e.g. Sunamura, 1977; Trenhaile, 2000). This model also includes the effect of wave attenuation depending on width of the surf zone. The offshore wave condition was constant during each run. The result of the experiment suggests that submarine terrace divided by relatively steep slope develops during the early stage of sea-level rise, despite the lack of rapid change of relative sea level and offshore wave condition. This autogenic submarine terrace is caused by an interaction between widening of the surf zone associated with cliff recession and consequential wave attenuation at the cliff base.