圖書典藏及影音數位平台

以往受限於現地量測不易，往往無法精準獲得多期合理正確土方量及其運移情況，近年航遙測技術發展日益精進，透過不同尺度遙測影像(例如光達、航空照片或無人載具等)，可產製1至2m精度之地表數值地形(DSM)與地面數值地形(DEM)，並合理估算集水區土方生產及河道土砂侵淤量，進而分析土砂運移趨勢及水庫入砂量等。 另過去受限於河道大斷面測量時程，欲推估水庫空庫排砂能力，因無法即時取得單一場次洪水事件之輸砂參數、地形變化量、沖刷深度等參數，故較難以準確評估輸砂量。然而近年來南化水庫先後完成自動化水文觀測測站，能提供全洪程流量及輸砂量資料，如輔以UAV取得單一場次洪水事件之地形變化量、沖刷深度資料，即能較準確率定空庫排砂之輸砂參數。 因此，本計畫目的在於應用航遙測影像產製數值地形，進而定量分析南化水庫集水區之土砂生產、坡面殘留土砂、河道侵淤、土砂運移量及空庫排砂量，以作為擬訂水庫防淤策略之參考。

The evaluation of the empty sediment flushing capacity is the key to the promotion of Nanhua second reservoir. In the past, the assessment of the flushing capacity of the empty reservoir was mainly based on the empirical formula of Jianshanpi Reservoir and the reservoirs of Mainland China, or the simulation results of numerical movable model. The analysis carried out by the numerical model simulation is more accurate. However, most of the model’s parameters only have been verified by cross section topographical data of rivers that span multiple typhoons or torrential rainfall events, and the accurate of verification is still insufficient, as well as the rationality of the results of sediment flushing capacity. In the estimation of the amount of sediment production in the catchment, the broadly used empirical formula of the landslide area and the landslide volume is greatly affected by the geological conditions, and it is difficult to accurately and reasonably obtain the landslide sediment production and residual amount. Based on mentioned above, the purpose of this project is to use the aerial photo generated high-resolution digital surface model (DSM), combined with the LiDAR generated digital elevation model (DEM), to track the sediment production and sediment flux into reservoir in the long-term through multi-temporal difference of digital terrain. In terms of assessment of sediment flushing capacity of empty reservoir, this project uses the unmanned vehicle UAV to perform aerial photography before and after the torrential rainfall event and produces high-resolution riverbed topography. Then combined with the real-time erosion observation of the riverbed during the rainfall event, a complete erosive process of a single event is obtained. The maximum scour depth and the back accretion height of the riverbed can be used as the basis for the verification of the numerical model, and further improve the empty sediment flushing capacity of the Nanhua second reservoir.