Numerical Simulation-based Risk Assessment Of Gangou Debris Flow In Baishahe River Basin

Baishahe river basin is the meizoseismal area of the "5.12" Wenchuan earthquake. On July 17, 2009 Gangou debris flow broke out a massive mudslides due to Baishahe river basin received a field intensity rainfall. Based on the theory of risk assessment and methods at home and abroad, this paper investigates the basic characteristics of the debris flow gully in Baishahe river basin, including the natural geographic and geological environmental conditions, etc., and focusing on partition characteristics of debris flow within the basin. Use FLO-2D software, rainfall,DEM and the Survey report data of "7.17" Gangou debris flow to analyze the accuracy of the Simulation of "7.17" Gangou debris flow, including depth, velocities and volumetric sediment, at the same time determines the numerical simulation parameters. Using beyond the probability statistical model, which is on the basis of rainfall intensity, calculate the rainfall threshold in 30, 50,100 and 200 years, "7.17" Gangou debris flow of return period is 200 years. According to the rainfall threshold in 30, 50 and 100 years and digital elevation model, simulats debris flow with engineering conditions or no. Base on the result of this study, we can predict the influence and scope of debris flow in 30, 50 and 100 years.This paper chooses the flow depth and flow velocity of the debris as the factor of hazard assessment, to make hazard assessment under different rainfall recurrence period and gets the hazard zoning map as a result. Within the scope of dangerous from the numerical simulation, combined with remote sensing data, using the Liu Xilin vulnerability assessment method to make comprehensive vulnerability assessment and gets the vulnerability zoning map as a result. Integrated risk assessment and vulnerability assessment, uses the risk assessment model to calculate the degree of risk under different rainfall recurrence period, and gets the risk zoning map as a result. This is done to provide the more scientific and reasonable basis for disaster prevention and mitigation work, and provide decision support for the sustainable development of economic, social and environment.