Axial incision and sediment dispersal of the Kaoping River － Submarine Canyon
system, SW Taiwan
Cheng-Shing Chiang a,* and Ho-Shing Yub
a
b
*
Hsiuping Institute of Technology, Taichung, Taiwan, ROC
Institute of Oceanography, National Taiwan University , Taipei, Taiwan, ROC
Corresponding author. Tel.: +886-4-2496-1114; fax: +886-4-24961187; E-mail address:
wind@mail.hit.edu.tw (C.-S. Chiang)
Abstract
The Kaoping Submarine Canyon, connecting directly to the Kaoping River
mouth in the coastal plain in SW Taiwan, continues the dispersal path of modern
Kaoping River sediments from an active small mountainous drain basin to the
receiving basin of the South China Sea. Using seismic reflection sections, Chirp
sonar profiles and bathymetric mapping this study reveals characteristic erosive
processes responsible for axial incision morphology and sediment dispersal in the
canyon that are closely related to the canyon-river connection setting.
The incision morphology changes along the course of upper reach of the
Kaoping Canyon. The proximal segment of the canyon is dominated by single valley
morphology.
Axial incision is observed in the distal meandering segment where
axial incision occurs mainly in the outer bend within a major sea valley. Axial incision
height ranges from 252 to 513 m, much greater than 40-150 m in relief of axial
incision of submarine canyons of Gulf of Lion, reflecting the present day conditions
of recurrences of cut-and-fill events during the canyon evolution probably since Early
Pleistocene.
The recurrences of presumed hyperpycnal flows have allowed continuous
incision of the canyon head and have kept the connection between the canyon head
and the river mouth during Holocene highstand of sea level. Oceanic flood
sedimentation operates in the Kaoping River - Canyon system, inferred hyperpycnal
flows flushing river sediments into the canyon head region where functioning as a
sediment conduit or a sediment bypass zone. Alternatively, the Kaoping Canyon head
segment can be considered as a temporary sediment sink rather than a major sink at
present.
Keywords: axial incision, oceanic flood sedimentation, mountainous river, submarine
canyon, Taiwan