Evaluation of Remedial Works for a Spillway on Landslide-dammed Lakes by an Earthquake: A Case Study in the Jiufengershan Landslide

2. Department of Soil and Water Conservation, National Chung Hsing University, Taiwan

Abstract: This study applied digital elevation models of different periods and long-term field monitoring data to compare elevation changes of a spillway for remedial works of landslide-dammed lakes in the Jiufengershan landslide. Digital aerial photogrammetry and LiDAR techniques were used to rebuild orthophotos and digital elevation models in the area from 1998 to 2015 in order to review the changes of deposit and erosion in topographies and profiles of the spillway. Through many torrential rainfalls in the past, it was particularly effective for the spillway and related remedial works to suppress the production and flow of collapse debris from banks of the spillway channel. It is the most important for spillway remedial works to remain the stabilization of two dammed lakes. Overall, average sediment amount of the two dammed lakes from 2007 and 2018 was only 0.33 m per year so the performance of the spillway would be well successful for the stabilization of the dammed lakes and the landslide area.