水庫沉滓運移模擬邊界條件之影響分析

Abstract

就水庫泥砂課題而言，泥砂入庫後之運移現象主要包含上游段粗顆粒造成之三角洲淤積行為，以及細顆粒入庫區後潛入形成異重流之運移行為。以數值模式的角度來看，沉滓運移現象模擬結果之準確度常受上游河床載邊界條件之設定，以及底床邊界再懸浮機制之影響。本研究之目的，即擬引用謝(2003)及鍾(2012)所發展之二維(RESED2D)以及三維(RESED3D)沉滓運移模式，探討上游及底床邊界條件對沉滓運移之影響。 為探討水庫沉滓運移模擬邊界條件之影響，分別先以三維模式模擬實驗案例，探討底床邊界條件對濃度傳遞的影響；再以二維模式模擬實驗以及現地案例，探討入流邊界條件對底床變遷的影響。最後，在簡單垂向入流濃度的假設條件下，將三維模式應用於石門水庫，以檢視模式之實用性。

In respect of sediment issue in reservoirs, the transport of sediment mainly involves with coarse particles in upstream that forms delta and fine articles in reservoirs that result in transport of density current. From numerical modeling view point, the accuracy of simulated results of sediment transport is often influenced by the bed-load boundary condition in upstream and resuspension mechanism of the riverbed boundary. This research adopts Hsieh’s (2003) two-dimensional (RESED2D) and Zhong’s (2012) three-dimensional (RESED3D) mobile-bed models to discuss the effect of upstream and riverbed boundary conditions on sediment transport. To examine the effect of boundary conditions of sediment transport modeling for reservoirs, this study first simulated experimental and on-site case with 2D model for discussion of inflow boundary condition’s effect on the change of riverbed. Then, the experimental cases were simulated with use of 3D model for discussion of the effect of riverbed boundary on delivery of concentration. Finally, with a hypothetical inflow concentration profile, the 3D model was applied to the Shi-men Reservoir to show its applicability.