Development of Advanced Sediment Replenishment Methodology for Bedload Continuity below Dams

安装额外的两台IP摄像机监测系统，一台安装在桥上，另一台安装在河流左岸，用于实时监测泥沙补给地点的泥沙侵蚀模式和SR地点附近的地表水流速度。此外，安装一个浊度计来测量悬浮泥沙浓度。总共在Naka River进行了四次实地调查，以测量沿四个砾石坝的粒度分布(GSD)，一架无人机用于沉积物补给地点，以及地形变化。法国布伊赫河的实地考察和资料收集。建立纳卡河和布赫河泥沙补给的综合评价方法，考虑补沙的侵蚀效率和下游生态水文地貌的影响。基于TELEMAC-2D和GAIA的耦合，建立了纳卡河实施SR后的二维水文地貌变化模型。然后，对以前的洪水事件和2022年的洪水事件对模型进行了校准和验证。然后，基于校准后的模型，我们利用该模型对几种情景进行了模拟，研究了考虑补给侵蚀和下游响应的SR优化策略。长谷古口大坝最近发生罕见的重大洪水，这表明在大坝管理下很难提高冲水量。

Installation of additional monitoring systems of two IP Cameras, one on the bridge and one on the left bank of the river, for real-time sediment erosion patterns at the sediment replenishment site and surface flow velocities near the SR site. Additionally, install one turbidity meter to measure suspended sediment concentration. In total, four times field surveys at Naka River for measuring Grain Size Distribution (GSD) along four gravel bars, a drone for the sediment replenishment site, and morphological changes. Field visit and data collection of Buech River in France. Develop a comprehensive assessment method for sediment replenishment in the Naka and Buch Rivers, considering the erosion efficiency of replenished sediment and downstream eco-hydro-geomorphological impacts. We established a two-dimensional model to simulate the hydro-morphological changes with the implementation of SR in the Naka River based on TELEMAC-2D coupled with Gaia. The model was then calibrated and validated for previous flood events and the 2022 flood event. Then, based on the calibrated model, we utilized it to simulate several scenarios to investigate the optimization strategies of SR by considering replenishment erosion and downstream responses. There are rare significant floods that occurred recently in the Nagayasuguchi dam, indicating that an increase in flushing magnitude is difficult to implement under dam management.