Formative Proceesses and Geomorphological Characteristics of Coastal Sand Dunes from the view point of sediment material

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We conducted research on historical development, formation processes and characteristic of geomorphology of coastal sand dunes in Japan from the sediment material points of view. Three field sites were surveyed intensively: the Enshu-nada Sand Dune at Shizuoka Prefecture, the Katamachi Sand Dune at Niigata Prefecture and the Tottori Sand Dune at Tottori Prefecture. The width of the coastal dunes along the Enshu-nada increases from 100m to more than 1,200m towards the east from the mouth of the Tenryu River. In contrast, moving away from the mouth of the Tenryu River, the beach width decreases from 260m to 30m. We surveyed size distributions of beach sediments and beach profiles and concluded that grain size distribution of berm deposits had clue to development of coastal dunes. Interaction between wave processes and blown sand ones were discussed. On the other hand, the Katamachi Sand Dune similarly illustrates that moving away from the mouth of the Seki River; size of the coastal sand … More dune increases. Mineral compositional surveys over the drainage basin of the Seki River revealed that longitudinal dunes were developed at c.a. 80,000-50,000y.B.P., triggered by the volcanic activity of the Myoukou Volcano. Historical formative processes of the Katamachi Sand Dune explain dimensional variations of the dune. Formation processes of the Tottori Sand Dune were surveyed with boreholes (named as B5 and B6) and microtremor measurements. With facies, sequence stratigraphy, diatom, pollen, paleo magne and electorical conductivity analyses as well, we are still discussing paleo environmental changes before the formation of the sand dune. In addition, formation processes of the Oigo-Suribachi at the Tottori Sand Dune were surveyed by wind tunnel experiments and proposed its conservational provision. As for countermeasures for meadow overgrowth at the Tottori Sand Dune, we conducted field experiments for vegetation mapagement using sandblasting and seawater spraying and got some valuable results. Less