A study of the Huapinghsu Channel/Canyon System was conducted with bathymetric profiles, 3.5 kHz echograms and box cores, to investigate morphology and sedimentary features. This channel/canyon system consists of two distinct units: (1) a broad trough-shaped channel which cuts into the shelf, and (2) a narrow V-shaped canyon with steep walls on the upper slope, which merges shoreward with the first channel. It extends from the shelf to the slope and has a total length of about 120 Km.
Core samples indicate that coarse-grained sediments are the dominant surface sediments in the channel and adjacent shelves but muddy sediments occur in front of the canyon mouth and nearby slopes. Erosional processes of lateral widening predominated in the channel course on the shelf and intense downcutting was prevalent in the canyon on the upper slope.
This channel/canyon system probably was initiated by sediment failure at the paleo-shelf edge. The canyon head then began to extend shoreward and resulted in a broad channel on the shelf. A er later submergence the channel/canyon system has been preserved and enlarged by marine processes and mass wasting.
The Huapinghsu Channel/Canyon System on the shelf and slope was a part of seaward sediment-transport systems during the late Pleistocene low sea-level stand. The subsequent transgression, some 5,000 to 7,000 years ago, inhibited the landward erosion of the channel. Because of cut-o from its main sediment source during the transgression, this channel/canyon system can no longer act as a modern conduit transporting sediments to the sea. The inadequate sediment supply from the China mainland and Taiwan has also prevented modern sediments from filling the submerged Huapinghsu Channel/Canyon System.