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This study was carried out on sediment samples collected by piston-coring in two areas of the eastern margin of the Japan Sea. One area is located at open sea conditions in the Oki Trough, o shore Kanazawa city, and the other is located in the enclosed bay conditions of the Joetsu Basin, o shore Joetsu city. Using these samples it was possible to di erentiate the source of the organic matter in the sediments of Holocene and late Pleistocene time on the basis of C and TOC/TN ratios coupled with palynofacies analysis. The Holocene sediments are characterized by high TOC and TN contents, low TOC/TN ratio, and heavier C values, which indicate a predominant marine organic matter production, probably due to warming and inflow of warm ocean currents and coastal currents along the East China Sea. These currents carried abundant phytoplankton from the Pacific Ocean as a result of the sea level rise. Occurrence of particulate organic matter shows abundant primary productivity during the Holocene under marine conditions. On the other hand, the LGM sediments are characterized by low TOC and TN contents, high TOC/TN ratio, and lighter C signatures, which are characteristic of terrestrial organic matter, probably due to seaward migration of shorelines and strong input of freshwater with terrestrial materials. This terrestrial influence decreased gradually from the LGM to the Holocene because of the sea level rise and consequent increase in the marine organic matter. : C Holocene sea level rise, Japan Sea, Last Glacial Maximum, organic matter, palynofacies, TOC, TOC/TN ratio Japan Sea is one of the typical back-arc basins of the world. It was formed behind the island-arc system of Japan Islands initiated by the rifting of the eastern margin of the Eurasian Continent at around Ma (Otofuji et al., ; Tamaki and Isezaki,). The opening was almost completed before Ma (Jolivet et al.,). At around the Middle Pliocene, the tectonic style had changed from the extensional to the compressive, and a series of NE-SW trending structures were formed along the eastern margin of Japan Sea (e.g., Okui et al.,). Umitaka Spur and Joetsu Knoll are two of these anticlinal structures, separated by the Joetsu-Umitaka Trough, south of Sado Island (Fig.). According to Oba et al. (), significant inflow of , ,

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Abstract. Geomorphic impacts of a disastrous crevasse splay that formed in September 2015 and its post-formation modifications were quantitatively documented by using repeated, high-definition digital surface models (DSMs) of an inhabited and cultivated floodplain of the Kinu River, central Japan. The DSMs were based on pre-flood (resolution: 2 m) and post-flood (resolution: 1 m) aerial light detection and ranging (lidar) data from January 2007 and September 2015, respectively, and on structure-from-motion (SfM) photogrammetry data (resolution: 3.84 cm) derived from aerial photos taken by an unmanned aerial vehicle (UAV) in December 2015. After elimination of systematic errors among the DSMs and down-sampling of the SfM-derived DSM, elevation changes on the order of 10 −1 m -including not only topography but also growth of vegetation, vanishing of flood waters, and restoration and repair works -were detected. Comparison of the DSMs showed that the volume eroded by the flood was more than twice the deposited volume in the area within 300-500 m of the breached artificial levee, where the topography was significantly affected. The results suggest that DSMs based on a combination of UAV-SfM and lidar data can be used to quantify, rapidly and in rich detail, topographic changes on floodplains caused by floods.