Modeling the travel distances of debris flows and debris slides: quantifying hillside morphology

Abstract

A travel distance model for debris flows and slides is presented based on information collected in southeast British Columbia, Canada. The model incorporates a variable that represents terrain morphology by a single number, quantification made using a one-to-one correspondence between the binary and decimal numeration systems. The terrain morphology coding has a site-specific character, providing a process-based representation of local conditions. Multiple regression analysis was used to assess the dependence of event travel distance on terrain morphology, slope, stand height, terrain curvature and canopy closure (R2 = 0.975, p < 0.001). The model fulfills all the assumptions and requirements of regression analysis (i.e. normality, homoscedasticity, non correlated errors, lack of colinearity or outliers). An independent data set was used to test the model. The model successfully predicted all but one of the test dataset events, and one of four outliers. The model consists of an equation that can be used in mass movement risk assessment associated, with different forest activities (e.g. harvesting, road building).