Integration of Topobathymetry Mapping Techniques for Siltation Monitoring in the Reservoir
Hanafie A.(a), Zahra Z. A. (b), Huang W. Y. (c) and Chang K.T. (d*)

a) Vice Leader, Strong Engineering Consulting Co., Shalu Township, Taichung County, 43342, amricohanafie17[at]gmail.com
b) Master student, Dept. of Civil Eng. And Environmental Informatics, Minghsin Uni. Of Science and Technology, Taiwan. zalfaafifahzahra[at]gmail.com, +886-919845642
c) Section Chief, Cadastral section, Xinzhuang Land Office, New Taipei City, Taiwan. why6311[at]gmail.com, +886-975069295
d) Professor, Dept. of Civil Eng. and Environmental Informatics, Minghsin Uni. of Science and Technology, Taiwan, +886-921214694
*ktchang1216[at]gmail.com

Abstract

Topographic and bathymetric surveying technologies provide critical data support and decision making references for the reservoir management. This paper integrates various advanced topographic and bathymetric mapping technologies to survey terrain and sedimentation around reservoirs. As surveying technologies advance, equipment such as LiDAR and Multibeam Echo Sounders (MBES) have significantly improved mapping accuracy in both terrestrial and underwater environments. LiDAR achieves 3~5 mm accuracy for terrain measurements, while MBES provides wide 150 degree swath coverage with up to 6 mm resolution for bathymetric mapping. However, an efficient and feasible integration is needed in shallow water and surrounding dense forests area. Data fusion approaches combine multiple systems to compensate for individual limitations in this work. In shallow or hard to reach areas, Unmanned Surface Vehicles (USVs) equipped with Single Beam Echo Sounders (SBES) and a mobile SLAM LiDAR system is utilized to enhance mapping completeness. Case studies include the Mingde Reservoir siltation monitoring, and the Hushan Reservoir interbasin water diversion project. It is worth noting that SBES equipped USVs conducted three rounds of surveys, also yielding 0.05 m RMSE. These results indicate that the technologies used in this case achieve high precision, comparable to MBES grade performance, especially for shallow water and land water interface mapping, outperforming traditional methods or SBES alone. Comparisons showed siltation of 0.3 to 2.0 m in two months at the Mingde Reservoir due to upstream river scouring, while Hushan Reservoir experienced the transbasin diversion caused up to -5.8 m of erosion and 0.4 to 2.5 m of downstream siltation. Temporal terrain model comparisons revealed two month siltation rates of 0.03 to 0.208 m in reservoirs. These findings highlight the importance of integrating diverse technologies for effective topographic and bathymetric mapping.

Keywords: Data Fusion, LiDAR, Echo Sounder, Topobathymetric, Siltation and Sedimentation

Topic: Topic B: Applications of Remote Sensing