Evaluation of DFLOWZ and Debris-2D Models Using Road No. 1081 Km. 90 Data in Northern, Thailand

In northern Thailand, devastating landslides and debris flow frequently occur after heavy rainfalls. This study focused on the evaluation of debris flow using the DFLOWZ and Debris-2D models. The data collected from the failure at Santisuk-Bo Kluea (No. 1081) road on 27 July 2018 were used to validate the model results. The total debris flow volume that occurred at the Santisuk-Bo Kluea (No. 1081) road was estimated using the Digital Elevation Model (DEM) analysis. The actual deposition and affected areas were depicted using aerial photos to validate simulated deposition areas. As a result, it is indicated that the DFLOWZ model provides a better agreement compared to the actual deposited area. It was found that the differences in the deposition area and the overlapping deposition area obtained from the DFLOWZ model are 16% and 34%, respectively. For the Debris-2D model with the minimum yield stress of 8000 Pa, the differences in the deposition area and the overlapping deposition area are 51% and 16%, respectively. It should be noted that prudential input parameters should be selected with caution. Especially, the yield stress, which is the main factor for the Debris-2D model, should be obtained from the testing suggested by Liu and Huang (2006)