SPATIALLY-EXPLICIT PREDICTION OF RAINFALL INTENSITY-DURATION THRESHOLDS FOR THE GENERATION OF POST-FIRE DEBRIS FLOWS IN THE WESTERN UNITED STATES
Traditional ID threshold methodology can be combined with logistic regression models that predict post-fire debris-flow probability to create a framework for the calculation of spatially-explicit ID thresholds. The approach presented here synthesizes these methods by incorporating rainfall terms into each model variable within the logistic regression equation. Model performance is evaluated not only by statistical results, but also by how well the model equation defines the rainfall intensity-duration threshold for individual basins for which a threshold has been identified. The model can be applied in a spatially-explicit manner, which allows for site-specific characterization of both the likelihood that a debris-flow will occur at a given rainfall intensity and direct calculation of the rainfall rates that will result in a given likelihood. With additional validation, this model may permit the prediction of spatially-explicit ID thresholds for debris-flow generation and allow for more rapid expansion of the USGS/NWS early-warning system into other susceptible regions.