Science and Education Publishing American Journal of Civil Engineering and Architecture 2328-3998 3 2 2015 03 19 Levee Breaching Process of a River and Disaster Risk on Floodplain 39 44 EN Md. Serazul Islam School of Agriculture and Rural Development, Bangladesh Open University, Gazipur, Bangladesh Tetsuro Tsujimoto AJCEA2015321 10.12691/ajcea-3-2-1 2015 03 01 2015 03 12 2015 03 19 Small-scale laboratory experiments and same scenario numerical analyses were conducted to understand levee breaching phenomena and subsequent disasters risk in floodplain focusing on the effects of the relative height of river bed to the floodplain and the bed materials. In the present study, the area including river, levee and floodplain has been reproduced in both experiment and numerical simulation because not only the behavior of levee but also the phenomena in river and floodplain are intimately related to one another. As a result the followings have been clarified: Higher bed level brings more rapid propagation of the levee breach and widening with more inundation and sediment deposition on the floodplain. River bed degradation in the upstream of the levee breaching point may cause further risk of breach. While as for the effect of bed materials, it has exposed that the finer materials has higher risk not only by more deposition on the floodplain but also by remarkable river bed degradation.