Implications of Flood Event Layers in Littoral Sedimentary Environments

Abstract

The fluvial supply and littoral dispersal of sediment exert profound influences on the way in which sandy beaches evolve. This paper looks at the importance of flood events in assessing the sediment budget in a littoral cell,with consideration of the grain-size dependency of sediment dispersal. The particular discussion focuses on the impact of a major flood that occurred at the end of July 2011 and brought a significant amount of sediment offshore through the mouth of a river(Okotsu diversion channel). The retrieval and facies analysis of three offshore sediment cores permitted the authors to identify the 2011 flood-event layer on top of each sediment core. The gamma-ray spectrometry revealed that the flood-event layer carried the March 2011 Fukushima-event-associated radioactive nuclides.