[U-03] Remote Sensing Role in Sustainable Development

[U03-P01] Analysis of Long-Term River Channel Morphological Changes

*Ya-Chen Yang¹、Chi-Farn Chen¹ (1.Center for Space and Remote Sensing Research, National Central University, Taiwan)

キーワード：River channel change, Satellite image, DSAS, SCE, EPR

Rivers in Taiwan are characterized by steep gradients, short river basins, and drastic hydrological conditions influenced by monsoons and typhoons. These extreme weather events contribute to rapid channel erosion and siltation, significantly impacting flood control infrastructure and the surrounding environment. Understanding long-term river channel changes is essential for effective water resource and river basin management. This study investigates the morphological changes of the Gaoping River channel, which belongs to Taiwan’s largest river basin and flows from northeast to southwest over a total length of approximately 171 km. The Digital Shoreline Analysis System (DSAS) was employed to quantify the evolution of river channel morphology over a 15-year period (2009–2024). High-resolution satellite imagery (Formosat-2 and SPOT) was digitized to generate annual river channel boundaries, providing a dataset for change detection. Two key metrics were analyzed: End Point Rate (EPR), which assesses the annual rate of channel movement between two time points and quantifies changes in the form of erosion and siltation patterns; and Shoreline Change Envelope (SCE), which measures the total change in channel movement over the study period. The results indicate that the confluence of the Gaoping River and its major tributary has undergone significant morphological changes, with the most pronounced channel shifts occurring 7 to 16 km upstream of the confluence. The average SCE for this reach is 267 m, with the most extreme change recorded between 2022 and 2023, reaching 663 m, indicating substantial instability. EPR analysis reveals that the left bank experienced an erosion rate of -254 m/year and a siltation rate of 174 m/year, while the right bank recorded an erosion rate of -151 m/year and a siltation rate of 191 m/year. The erosion intensity on the left bank was notably higher than on the right bank, whereas siltation was more pronounced on the right bank. These findings demonstrate that this river reach has experienced highly dynamic channel changes. Further comparison with historical dredging activities suggests that dredging has significantly influenced erosion and siltation processes, affecting the stability of the river channel. These results emphasize the necessity of strategically distributed dredging areas to minimize channel disturbances and maintain long-term stability. Additionally, integrating long-term satellite monitoring and remote sensing techniques will enhance river management strategies, improve flood risk assessment, and support more effective watershed management policies.