[H-TT14] HIGH-DEFINITION TOPOGRAPHIC DATA FOR CONNECTIVITY IN THE ANTHROPOCENE

[HTT14-03] Analysis of sediment deposition using RTK-UAV: A case study of Echi River, central Japan

*Takuro Ogura¹, Toshiaki Mizuno², Daisuke Yamanaka³, Yuichi S. Hayakawa⁴ (1.Faculty of Life and Environmental Science, University of Tsukuba, 2.Lake Biwa Environmental Research Institute, 3.Lake Biwa Museum, 4.Faculty of Environmental Earth Science, Hokkaido University)

Keywords:RTK-UAV, sediment deposision, DSM, Echi river

Public works using three-dimensional (3D) data has been carried out in various institution. UAVs have been widely spread and utilized to acquire 3D data. However, it is necessary to ensure 3D accuracy when conducting UAV measurements. It is also required to spend a lot of work time and cost using GCPs (Ground Control Points). Here we show that UAV equipped with RTK-GNSS to calculate the amount of sediment deposition in two periods. The study area is 10 km from the mouth of the Echi River in Shiga Prefecture. We took photos using RTK-UAV in July 2021 and September 2021. We also created DSMs and ortho-images from the images using Agisoft Metashape Professional. The accuracy of DSMs was about 1 cm. Heavy rainfall occurred between July 2021 and September 2021, which increased the dam's water release upstream. As a result, the water release rate of about 1300 m³/s lasted for about 6 hours, and sediment deposition was observed. Therefore, the amount of sediment deposited could be calculated with high accuracy for sedimentation areas with shallow water depths. Therefore, the amount of sediment can be quickly measured in a small river with high precision.