In the 10-year return period, most of the Froude numbers are beyond 0.5 and less than 3, making most of the sites fall into the antidunes form, indicating that such floods could create antidunes in Shi-Wen River.
Further, torrential rains and typhoons can alter the bed form in a very short period to either antidunes or transition form, depending on their magnitudes in the study herein.
It should be noted that at still higher flows in shallow rivers, upper flat beds give way to upstream migrating bedforms known as in-phase waves or antidunes
. If river flow increases still further, antidunes
disappear and chutes and pools form.