Japan Geoscience Union Meeting 2015

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Symbol H (Human Geosciences) » H-QR Quaternary research

[H-QR23] Diachronic dynamics of human-environment interactions

Sun. May 24, 2015 10:00 AM - 10:45 AM 101A (1F)

Convener:*Takahiro Miyauchi(Department of Earth Sciences, Graduate School of Science, Chiba University), Takashi AZUMA(National Institute of Advanced Industrial Science and Technology), Yoshinori MIYACHI(National Institute of Advanced Industrial Science and Technology), Chair:Takahiro Miyauchi(Department of Earth Sciences, Graduate School of Science, Chiba University)

10:30 AM - 10:45 AM

[HQR23-03] 3D analysis of a sandy point bar in the Yahagi River, central Japan, using GPR survey

*Hiroko OKAZAKI1, Youngjoo KWAK2, Toru TAMURA3 (1.Natural History Museum & Institute, Chiba, 2.International Centre for Water Hazard and Risk Management under UNESCO, Public, 3.Geological Survey of Japan, AIST)

Keywords:GPR survey, sandy point bar, Yahagi River, Japan

We conducted a ground-penetrating radar (GPR) survey of a sandy point bar in the Yahagi River, central Japan, to clarify the three-dimensional (3D) depositional facies. The survey was conducted in January 2015 using a 250-MHz antenna. Surveyed bar, which is 725 m long, 160 m wide, is composed of two or more rows of bars. Three-dimensional dunes characterize the surface of middle- lower downstream parts. We identified inclined reflections, horizontal reflections, and trough-shaped reflections in the bar. Inclined reflections are predominant in longitudinal sections, and horizontal reflections and trough-shaped reflections are common in transverse sections. These reflections represent downstream migration of the bar, developments of three-dimensional dune, chute channel during floods.