A numerical model study for simulation of rocky coast evolution and erosion using cosmogenic nuclides: A case study along the Dunduri and Dokdo shore platform in Korea

The current and future climate change and human interventions would increase flood and erosion risk in coastal areas, and thus more coastal erosion studies are needed. Here, we used cosmogenic nuclide concentrations along the Dunduri and Dokdo shore platform in Korea combined with numerical modelling to quantify cliff retreat rate and to reconstruct the timing of initial cliff retreat and the evolution of shore platform. Theoretically, the hump in nuclide concentrations is resulting from the interplay between cliff retreat and water shielding by rising sea level. If a portion of the platform inherited from last interglacial, a sharp increase in cosmogenic nuclide concentrations at the past cliff position is expected, reflecting the nuclide accumulation on exposed shelf during sea level lowstand in last glacial. Also, faster cliff retreat leads to lower nuclide concentrations. The results of our numerical modelling show that a portion of Dunduri platform inherited from last interglacial due to elevenfold increase in nuclide concentrations, and calculated cliff retreat rate is about 0.6-12 mm/yr. Dokdo platform, however, no abrupt change in nuclide concentrations is observed, thus the platform was entirely formed during the Holocene, and calculated cliff retreat rate is about mm/yr.