Magnitude amplification of flash floods caused by large woody in Keze gully in Jiuzhaigou National Park, China

Wood is an important component of flash floods and debris flows in forested mountainous areas. To better understand the characteristics large wood (LW) movement its destructive effects on check dams, bridges, buildings, we conducted field investigations theoretical calculations flood process Keze gully Jiuzhaigou National Park (China). Based calculation method, magnitude amplification ratio peak discharge caused by clogging breakage processes associated with LW transport reached 2.83 to 3.03 times mean upstream dam No. 1. Moreover, limit analysis limiting equilibrium state methods were adopted analyze additional impact force sidewalls which resulted sidewall breaking sediment block function loss dam. Furthermore, analyzed pattern formulated a conceptual model transport, including length, channel width, standing tree spacing. Through this case study, put forward that should be considered design construction mitigation engineering projects