台灣早期水庫興建時並未設置排砂設施，受限於地質、地形與水 文條件極端化，水庫淤砂問題嚴重，將影響水庫壽命，已成為當前水資源 供需關鍵課題，因此，水庫清淤為維持水庫壽命重要方法之一。本研究以 曾文水庫下游河道實際放淤案例，進行二維CCHE2D動床模擬，以瞭解及 掌握水庫之淤積物，經洩洪沖淤自然回歸河道後，對曾文溪下游河道之影 響及變遷之狀況瞭解。

Due to the limitation of geology, morphology, extreme hydrology condition, and no construction of reservoir sediment desilting facility in early period of Taiwan, sedimentation problem has become severe and threaten the usage life of reservoir. As a result, sediment flushing by reservoir flooding has become a novel approach in recent years. Here, we take Zengwen reservoir silt disposal operation strategy for an example. Two dimensional numerical movable-bed model, CCHE2D, has been used to simulate the channel variation after reservoir flushing. The modeling result could understand the transportation behavior of sediment deposition of reservoir after flushing with flood and its impact on the morphology transition of downstream channel.