A tank model is a conceptual model which simulates the moving behavior of water in the soil layers, including runoff, infiltration and percolation. The water depths of three tanks, representing surface, middle and deeper soil layers, respectively, were summed up as a soil water index (SWI). This study analyzes the debris flow cases in Eastern Taiwan based on the tank model and the current warning threshold value for debris flow. Results showed SWI has a linear relationship with the depth in the second tank, i.e. the soil moisture in the middle soil layer is closely related to the occurrence of debris flow cases. In addition, debris flow occurred when SWI>107mm. This finding can be used as a warning for debris flow in Eastern Taiwan.
A tank model is a conceptual model which simulates the moving behavior of water in the soil layers, including runoff, infiltration and percolation. The water depths of three tanks, representing surface, middle and deeper soil layers, respectively, were summed up as a soil water index (SWI). This study analyzes the debris flow cases in Eastern Taiwan based on the tank model and the current warning threshold value for debris flow. Results showed SWI has a linear relationship with the depth in the second tank, i.e. the soil moisture in the middle soil layer is closely related to the occurrence of debris flow cases. In addition, debris flow occurred when SWI>107mm. This finding can be used as a warning for debris flow in Eastern Taiwan.