外文翻译---CCHE1D渠道网络模型的灵敏度分析

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1、PDF外文：http:/   附录一：外文原文  Sensitivity Analysis of the CCHE1D Channel Network Model  Weiming Wu (1), Dalmo A. Vieira (2), Abdul Khan (3) and Sam S. Y. Wang (4) (1), (2), (3) and (4), National Center for Computational Hydroscience and Engineering, School of Engineering, The University of

2、 Mississippi, MS 38677； PH (662) 915-5673 / (662) 915-7788； FAX (662) 915-7796； E-mail: wuwmncche.olemiss.edu Abstract The CCHE1D model was designed to simulate long-term flow and sediment transport in channel networks to support the DEC project. It uses either the dynamic wave or the diffusive wave

3、 model to compute unsteady flows in channel networks with compound cross sections, taking into account the effects of in-stream hydraulic structures, such as culverts, weirs, drop structures, and bridge crossings. It simulates non-uniform sediment transport using a non-equilibrium approach, and calc

4、ulates bank toe erosion and mass failure due to channel incision. The CCHE1D model decouples the flow and sediment transport calculations but couples the calculations of non-uniform sediment transport, bed changes and bed material sorting in order to enhance the numerical stability of the model. In

5、this paper, the sensitivity of CCHE1D to parameters such as the non-equilibrium adaptation length of sediment transport and the mixing layer thickness is evaluated in cases of channel aggradation and degradation in laboratory flumes as well as in a natural channel network. In the case of channel deg

6、radation, the simulated scour process is not sensitive to variation in values of the non-equilibrium adaptation length, but the determination of the mixing layer thickness is important to the computations of the equilibrium scour depth and of the bed-material size distribution at the armoring layer.

7、 The simulated bed profiles in the case of channel aggradation and the calculated sediment yield in the case of natural channel network are insensitive to the prescription of both the non-equilibrium adaptation length and the mixing layer thickness. The CCHE1D model can provide reliable results even

8、 when these two parameters are given a wide range of values.   Introduction   The CCHE1D model was designed to simulate long-term flow and sediment transport in channel networks to support the Demonstration Erosion Control (DEC) project, which is an interagency cooperative effort among the

9、 US Army Corps of Engineers (COE), the Natural Resources Conservation Service (NRCS) and the Agricultural Research Service (ARS) of the US Department of Agriculture. The CCHE1D version 2.0 was based on the unsteady flow model DWAVNET (Diffusion WAVe model for channel NETworks, Langendeon, 1996) and

10、the sediment transport model BEAMS (Bed and Bank Erosion Analysis Model for Streams, Li et al., 1996). It was significantly improved by implementing the dynamic wave model and the non-equilibrium sediment transport model (Wu, Vieira and Wang 2000). The CCHE1D was integrated with the landscape analys

11、is tool TOPAZ (Garbrecht and Martz, 1995) and with the watershed models AGNPS (Bosch et al., 1998) and SWAT (Arnold et al., 1993), through an ArcView GIS-based graphical user interface (Vieira and Wu, 2000). The CCHE1D has been successfully tested in various experimental and field cases. Because sev

12、eral parameters in CCHE1D must be prescribed empirically, it is very important to know the response of the model to the uncertainty of these parameters. In this study, the sensitivity of CCHE1D to model parameters such as the non-equilibrium adaptation length of sediment transport and the mixing lay

13、er thickness is analyzed in cases of channel aggradation and degradation in laboratory flumes as well as in a natural channel network.   Description of the CCHE1D Channel Network Model  Hydrodynamic Model. The CCHE1D flow model simulates unsteady flow in channel networks with compound cros

14、s-sections using either the diffusive wave model or the dynamic wave model. The dynamic wave model solves the full St. Venant equations. The Preissmann implicit,four-point, finite difference scheme is used to discretize the governing equations. Linearized iteration schemes for the discretized govern

15、ing equations are established and solved using a double sweep algorithm. The influence of hydraulic structures such as culverts, measuring flumes, bridge crossings and drop structures has been considered in the CCHE1D model. Stage-discharge relations for hydraulic structures are derived so that the

16、hydraulic structures become an intrinsic part of the numerical algorithm.    Sediment Transport Model. The CCHE1D model calculates non-uniform sediment transport in rivers using a non-equilibrium approach. The governing equation for the non-equilibrium transport of non-uniform total load is