The aim of this paper is to investigate the mechanism of the fission process and the flow field of N-waves in the near-shore region. From the elaborate experimental analysis, a subsequence of a second soliton released during shoaling reigon is identified to realize the further evolution of N-waves over a sloping beach, in comparison with the non-fission case. The fission index is indicated by a dimensionless factor A0/d0, which is used to describe the nonlinearity as well. It is known that the reflecting wave and the breaking effect could easily initiate another soliton, especially for strong nonlinear case. A series of experiments were conducted in a super wave flume (300m × 5m × 5.2m) at Tainan Hydraulics Laboratory (THL), National Cheng Kung University (NCKU). The entire evolution of the leading and second solitons and the generation mechanism for the third soliton would be discussed in this paper.
