This study provides longitudinal and cross-sectional analysis of 8 pieces topography data collected from 1980 to 2011 and bed material particle size based on three investigations conducted between 2008 and 2012. The mainstream topography data in December 2007 shows that
the head-cutting distance was about 3 kilometers after the dam broke. The topography data since 2008 displays that river the channel is stable as well. The topography data shows that the longitudinal section in the tributary had a head-cutting distance of about 3 kilometers after the dam broke, and the river channel still is showing adjustment behavior. The scour-and-fill analysis result of the mainstream cross-section shows that the transverse adjust changed significantly upstream from the dam location from 2006~2008. The particle size of the bed material has shown a trend from coarsening to fining according to different sampling points. Therefore, the river bed is still adjusting continuously.Finally, this study is based on a debris flow and sediment laden flow numerical model. The simulation
result is fit for river-bed changes after dam-break.
Key Words : Baling dam, check-dam failure, river-bed variation, numerical simulation.