The Application of FLO-2D Scour and Deposition Model on Debris-flow Influence Zone Analysis - Study on the Tong-Pan-Jei Creek, Ilan County

• Main Authors: Chih Yan Lin, 林芝岩
• Other Authors: Y. C. You
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/98866332938225021614

碩士 === 國立宜蘭大學 === 土木工程學系碩士班 === 95 === According to the Theory of Plate Tectonics, Taiwan is located at the boundary of Philipines Sea Plate and the Euro-Asia Continent Plate. Through the influence from plate collision, the geological condition in Taiwan is considered to be harsh with complex geologic structures as well as steep terrain and frequent earthquakes. In recent years, the rapid economical growth in the region caused improper hillside developments over some steep slopes. As a result, severe soil scouring and landslides occurred very often during the heavy rainfall brought in during Typhoon season. Furthermore, debris flow hazards induced by high intensity rainfall along with huge cumulated precipitation were reported to cause fatal impact on human lives and assets. In this research, the Tong-Pan-Jei Creek (numerated as the Potential Debris Flow Creek Yilan-A120) was studied for its disaster history. In fall 2000, Typhoon Shan-Shen hit Taiwan with extremely high rainfall which induced the occurrence of several debris flows in the area and damaged both No. 2 Provincial Highway and the North Railway. As the result, Yilan County was isolated for more than a week due to the shutdown of outward transportations. In the incident, debris flow of Tong-Pan-Jei Creek played a major role. Rainfall records of Tou-Chen city during Typhoon Shan-Shen were used as the basic data in analyzing the scouring and deposition effects of debris flow in Tong-Pan-Jei Creek at the time. Numerical scheme FLO-2D was introduced through the analysis and various remedial schemes were simulated to evaluate their efficiency in preventing further debris flow. Before other simulations, the effective rainfall period previous to the occurrence of debris flow was determined comparing the results from both numerical calculation and reports at the debris flow site. Different sediment concentrations were then introduced in the numerical scheme to represent the effectiveness of slope stability and soil conservation measures of the watershed basin. In addition, flow channel along with check dams and sediment containment basin were also modeled into the simulation scheme to evaluate the possible extent of the debris flow sediments. Results from this research will provide the area of influence from the Tong-Pan-Jei Creek debris flow as the basic information in the local evacuation and rescuing route planning for debris flows. Besides, the methodology developed in this research could be used in evaluating the effectiveness and benefit for the rehabilitation of potential debris flow creeks.