[A-CG37] Water and Sediment Dynamics from Land to Oceans [En]

[ACG37-P01] Control of the Taitung Submarine Canyon Connected to the Shoreline and Its Effect on Canyon Activity

Jui-kun Chiu¹, Jih-Hsin Chang², Kuo-Jen Chang³, Nai-Kuang Wu⁴, Arif Mirza⁵, Chien-Yu Huang^2,5, Ho-Han Hsu^2,5, *Cheng-Shing Chiang⁶ (1.National Museum of Marine Science & Technology, Taiwan - NMMST, 2.Institute of Oceanography, National Taiwan University, Taipei, Taiwan - IO NTU, 3.Department of Civil Engineering, National Taipei University of Technology, Taiwan - CE NTUT, 4.Water Resources Planning Institute, Water Resources Agency, Ministry of Economic Affairs, Taichung, Taiwan - WRPI WRA MOEA, 5.Oceanography Center, National Taiwan University, Taipei, Taiwan - OC NTU, 6.Department of Geology, National Museum of Natural Science, Taichung, Taiwan - DG NMNS)

Keywords:Beinan River, Taitung Submarine Canyon, morphology, turbidity currents, river-canyon connection, Taiwan

The Beinan River is one of the largest rivers in eastern Taiwan, and it connects with the Taitung Submarine Canyon (TSC), eventually flowing into the Ryukyu Trench. By examining the morphology of the canyon heads through bathymetry data, the TSC presents a tributary of the TSC head and connects to the shoreline. Using seismic profiles and bathymetric mapping, we reveal erosive processes responsible for entrenched channels and slumps on the canyon walls, which are related to turbidity currents along a tributary of the TSC head (Zhiben River mouth). The deposition of fluvial sediments near the head of the canyon can indeed lead to an unstable slope, which is able to facilitate large-scale failure when earthquakes and extreme climate events occur. Such events can significantly alter the landscape and have far-reaching environmental impacts. The river-canyon connection, along with extreme climatic conditions and frequent earthquakes, is favorable for the generation of turbidity currents at the canyon head. The recurrence of turbidity currents has allowed continuous incision of the canyon head and has maintained the connection between the canyon head and the shore during the Holocene sea-level rise.