The Topographical and Rainfall Characteristics of the Landslide-triggered Debris Flow in Laofou Village

• Main Authors: Hung-Ju Shih, 施虹如
• Other Authors: 陳樹群
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/93805929984336559923

碩士 === 國立中興大學 === 水土保持學系所 === 101 === The heavy rainfall events with high intensity and long duration increased in the recent years in Taiwan, and the increasing heavy rainfall events also induced the complex disasters. The study focuses on the simulation of the landslide-triggered debris flow in Laofou Village in Pingtung County caused by Typhoon Namando during August 27 to 31, 2011. The study adopts the TRIGRS model to assess the landslide potential in the Laofou watershed, discusses the geomorphologic and rainfall characteristic of Laofou landslide, and uses FLO-2D to simulate the debris flow-induced disaster in the Laofou village. The study also uses Tank model to transfer the hourly rainfall to the surface runoff discharge which is used in the simulation of debris flow disaster. The TRIGRS can do the simulation of landslide potential in the Laofou watershed, but the accuracy of the simulation is not good because the study is deficient in the geological and hydrological data. The slight slide and erosion-induced bare surface had appeared in the source of south branch in the Laofou watershed after 2005 Typhoon Heitan, 2006 Earthquake, and 2009 Typhoon Morakot. The rainfall in the four days rainfall during 2011 Typhoon Nanmado infiltrates into the stratum from the tension cracks on the concave topography in the source of south branch in the Laofou watershed, and it also saturated soil, high ground water table, and the following large landslide. Based on the simulation result of FLO-2D for the three debris flow events in the Laofou watershed with the assumption of volumetric concentration as 0% from first to thirty-ninth hrs, 30% from the thirty-ninth to fortieth hrs, the simulation result shows both of the volumetric concentration of the second and third debris flow events are 48%. And the simulation result is very close to the real deposition in the Laofou watershed.