1. Assistant Research Fellow, Tainan Hydraulic Laboratory, National Cheng Kung Univ., 709 Tainan, Taiwan (corresponding author).
2. Professor, Dept. of Civil Engineering, National Chung Hsing Univ., 402 Taichung, Taiwan.
3. Chief of Physical Modeling Division, Tainan Hydraulics Laboratory, National Cheng Kung Univ., 709 Tainan, Taiwan.