[A-HW22] River Channel Morphology, Water Resource Management, and Advanced Techniques

[AHW22-03] Evaluation of the effectiveness of river dredging using sediment budget management and numerical scouring and siltation model case study of LaKuSher Creek in Southern Taiwan

*Bing-Shyan Lin¹, I-CHIA CHIU¹ (1.Feng Chia University)

Keywords:Dredging, Sediment Transport, CCHE1D, typhoon

Following the catastrophic impact of Typhoon Morakot in 1998, the Law-Long River watershed became a critical area for sediment-related disasters in southern Taiwan. The government agency implemented multiple dredging projects to mitigate sediment accumulation. At the confluence of LaKuSher Creek in the upper reaches of the Law-Long River, a Digital Surface Model (DSM) was utilized to assess topographic changes and analyze sediment transport dynamics through multi-temporal imagery. The CCHE1D one-dimensional mobile bed model was employed to simulate sediment transport processes in key disaster-prone sections at the confluence. Model validation was conducted by comparing simulated bed elevation changes with field survey data from disaster events in 2020 and 2021, demonstrating consistency with observed trends. Further analysis was carried out to evaluate sedimentation trends upstream and downstream of the confluence under design flood conditions corresponding to return periods of 5, 25, and 50 years. The results indicate that during extreme rainfall events associated with these return periods, the average deposition depth in LaKuSher Creek ranges from approximately 2 to 5 meters. It is recommended to regularly assess the available flood conveyance capacity in the area, particularly before typhoons and heavy rainfall events, to ensure the safety of nearby settlements.