Assessment of Natural Dam Occurrence Caused by Debris Flow

• Main Authors: Yan-RongHuang, 黃彥融
• Other Authors: Chjeng-Lun Shieh
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/00310606390098750876

碩士 === 國立成功大學 === 水利及海洋工程學系 === 103 === Landslide dams, which is formed by large scale soil and rock mass moved by tributary rushing into the mainstream, have been recognized as serious natural hazards in Taiwan. The failure of a landslide dam results in rush flooding flow in the downstream catchment. This flooding hazard damages local economics. People are injured and become homeless due to these events. In this study, the formation of landslide dams caused by debris flow can be categorized into two conditions: (1) the sediment transported by debris flow reaches across to the river; (2) the height of landslide dam caused by debris flow is higher than the water depth in situ. The assessment method, which evaluates the formation of landslide dam caused by debris flow, is established according to the abovementioned formation conditions. The assessment results classify the formation mechanism into 4 types: (1) the debris flow reaches across to the river and forms the landslide dam; (2) the debris flow reaches across to the river but overtopping failure suddenly occurred; (3) the debris flow does not reach across to the river but the sediment is partially above the water table; (4) the debris flow does not reach across to the river and the sediment is fully submerged in the water. Based on the verification of field cases and experiment, the assessment results show good agreement with the realistic phenomenon. By using this assessment method, the government offices can preliminarily determine the potential area of landslide dams caused by debris flow and prevent the future disasters accordingly with a properly prepared response plan.