The application of UAV photogrammetry to monitor the deformation of side-slope protection: A case study of Khwae Noi Bamrungdan Dam, Phitsanulok Province

Abstract

Inspecting and monitoring the deformation of the dam and surrounding areas are very important to assess the safety of the dam in irrigation work. However, for deformation monitoring in steep slope areas especially side-slope, it is very difficult to measure and monitor compared to traditional survey methods. This research aims to employ Unmanned aerial vehicle (UAV) photogrammetry for monitoring the deformation of side-slope protection in the downstream area of the dam. The study area was in Khwae Noi Bamrungdan Dam, Phitsanulok Province. The images were captured from the DJI Zenmuse X5S camera mounted on the DJI Inspire 2 UAV acquired in February 2022 and were processed using ContextCapture software for 3D reconstruction in the form of point cloud. Then, the deformation monitoring of side-slope protection was evaluated by comparison with the UAV photogrammetry of Royal Irrigation Department (RID) acquired in April 2018 using M3C2 technique on the CloudCompare software. The results showed that the accuracy assessment of the 3D model from UAV photogrammetry comparing to the RTK-GNSS survey had a square root of mean square error (RMSE) of 0.104 m. However, for the results in deformation monitoring over this study area, no significant changes were detected due to the photogrammetric accuracy of UAV approach in decimeter level. Therefore, the application of UAV photogrammetry can be an alternative way to detect changes and monitor deformation in steep slopes for irrigation works easily.