Short-term changes in seafloor character due to flood-derived hyperpycnal discharge: Typhoon Mindulle, Taiwan, July 2004

During Typhoon Mindulle in early July 2004, the Choshui River (central-western Taiwan) discharged similar to 72 Mt of sediment to the eastern Taiwan Strait; peak concentrations were >= 200 g/L, similar to 35%-40% of which was sand. Box-core samples and CHIRP (compressed high-intensity radar pulse) sonar records taken just before and after the typhoon indicate that the hyper-pycnal sediment was first deposited adjacent to the mouth of the Choshui, subsequently resuspended and transported northward (via the Taiwan Warm Current), and redeposited as a patchy coastal band of mud-dominated sediment that reached thicknesses of 1-2 m within megaripples. Within a month most of the mud was gone, probably continuing its northward transit, but more mud appeared in late August in response to Typhoon Aere. Following autumn and winter storms, the entire nearshore area was again sand dominated by early spring.