37 short–duration rainfall events were analyzed and compared with the runoff variation obtained from field measurement. The grey relational analysis was utilized to rank the influence of affecting factors on runoff variation. Three runoff prediction models using MLS, GABP and GASVM methods respectively were developed and compared. The debris flow hazard was assessed based on IDF curves and the predicted runoff. The proposed forecasting method for debris flow combined the empirical threshold with the physical process model.