The application of UAV photogrammetry, RTK-GPS and Terrestrial laser sacn techniques to investigate the short-term coastal change of Chi-Sing Tan, Hualien

• Main Authors: Chien-Hua Chen, 陳建華
• Other Authors: Yo-Ho Chang
• Format: Others
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/84229150218202557109

碩士 === 國立東華大學 === 自然資源與環境學系 === 104 === Hualien is one of the most vulnerable regions when typhoon strikes Taiwan. The strong winds and waves of typhoon cause damage to the coastal areas in a very short period resulting in coastal erosion. These events have strongly threatened the people living in the coastal area. To prevent the damaging effects of the strong waves on the populated coast areas, the original natural coast gradually has been replaced by artificial armor blocks. However, at some tourist hot spots, there are no large-scale man-made structure used to protect the coastal areas and we observed significant coastal changes in these areas after typhoon events, for example the coast from Chi-Sing Tan to Chi-Lai Bi, Hualien. Traditionally, the investigation of coast changes adopted points (benchmark height change) and linear (cross section across the coast) survey monitoring methods. Large area survey monitoring using airborne LIDAR or aerial/satellite photogrammetry is rare and expensive. There is a need for establishing a timely and cost-effective large area survey monitoring method for coastal change studies. This study utilized the UAV images between 2014 and 2015 at Chi-Sing Tan Coast, including images of July 2014, July 2015 before a typhoon and August 2015 after the typhoon event. The coast also scaned by using Terrestrial Laser Scanner (TLS) and using Real-Time Kinematic Global Positioning System (RTK-GPS) to collect ground truths validation data. The overall coastal changes estimated by using Arcmap DSAS (Digital shoreline Analysis system) module to calculate the shoreline change in each period. The area of study area is about 5.84×10^5 m^2, and its volume is 1.1306×10^7 m^3. The results show:(1)Coast retreat by a maximum distance of 4.47 meters, its volume reduced 3.88×10^5 m^3(3.4% of total volume) between July 2014 and July 2015.(2)After typhoon struck, the coast retreat by a maximum distance of 14.09 meters, its volume reduced 1.156×10^6 m^3 (10.2% of total volume) between July 2015 and Agust 2015.(3) Short-term Chi-Sing Tan coastal retreat occurred mainly in bike trails and Chi-Lai Bi sea cliff areas where have no man-made structure protecting the coast.(4) The height calculated by UAV photogrammetry is 0.195 meters lower than those TLS result, indicating the height accuracy of UAV photogrammetry is about 0.2 meters. The UAV photogrammetry could provide fast and accuracy survey data for long term coastal change monitoring